T VN Apatit l h khong photphat ca canxi c cng thc chung l Caio(P04)6M2, gm bn dng thng c nhc n l hyroxyapatit, floro apatit, cloro apatit v bromo apatit vi M = OH, F, Cl, Br tng ng. Trong bn dng ny, hyroxyapatit (vit tt l HA) ang c tp trung nghin cu do cc c tnh qu gi nh c hot tnh v tng thch sinh hc cao vi cc t bo v cc m, to lin kt trc tip vi xng non dn n s ti sinh xng nhanh m khng b c th o thi [22], [23]... HA c cu trc tinh th thuc dng lc phng hoc dng n t. Do c cng bn cht ho hc v cu trc, HA l dng canxi photphat d hp thu nht i vi c th con ngi v c t l Ca/P ng nh t l Ca/P t nhin trong xng v rng.Cc nghin cu tp trung vo tng hp HA cc dng bt mn v siu mn, dng khi xp, dng mng bng cc phng php khc nhau v kho st cc c tnh ca chng m rng kh nng ng dng. dng bt, cc nh nghin cn ang c gng iu ch HA kch thc nano (trong khong 20 - 1 OOnm) gp phn nng cao kh nng hp th ca c th. HA bt dng vi tinh th cng vi mt s khong cht b sung khc c dng trong bo ch thuc chng long xng v thc phm chc nng b sung canxi, x l cc khuyt tt trong xng do chn thng... dng mng, mt lp mng HA mng ph trn gm nhn to c th tng cng kh nng lin kt gia xng nhn to vi m v xng t' nhin.HA dng khi xp c ng dng sa cha cc khuyt tt ca xng v rng. Ngoi ra, cc nghin cu cho thy, HA dng khi xp bn trong cc dch sinh l ca c th v c tc dng nh chm cc dc cht i km vi n [25], [26]. nc ta, cc vt liu v c c kh nng ng dng trong y sinh hc ni chung v dc phm ni ring c quan tm t lu. Tuy nhin, vic ng dng cc vt liu v c trong y sinh hc v dc hc cn nhiu hn ch. T nm 2005, nhm nghin cu thuc Phng Ho V c, Vin Ho hc (Vin KH&CN Vit Nam) thc hin cc nghin cu v tng hp vt liu HA dng bt [5] v dng xp [27] hng n ng dng trong dc hc v y sinh hc. gp phn hon thin quy trnh ch to HA kch thc nano ng dng trong y sinh hc v dc hc, ti la chn ti: Nghin cu cc yu t nh hng n bt hyroxyapatit Ca10(PO4)6(OH)2 kch thc nano iu ch t canxi hyroxi Ca(OH)2.Cc c trng quan trng ca bt HA nh n pha, tinh th, hnh dng, kch thc ht... c nh hng rt ln n hiu qu s dng. Do vy, trn c s tng hp bt HA kch thc nano, lun vn tp trung vo kho st cc yu t nh hng n cht lng sn phm ( n pha, tinh th, kch thc ht...) theo nhng ni dung sau: Kho st nh hng ca nhit . Kho st nh hng ca tc cp axit. Kho st nh hng ca nng cht phn ng ban u. Kho st nh hng ca cc loi dung mi trong hn hp phn ng (nc, etanol, hn hp etanol + nc). Kho st nh hng ca tc khuy trn. Nghin cu s b nh hng ca hiu ng siu m.Trn c s cc kt qu nghin cu thu c, la chn cc thng s cng ngh cho quy trnh sn xut HA.-2-

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CHNG I: TNG QUAN1.1. Tnh cht ca hyroxyapatit1.1.1. Tnh cht vt lHydroxyapatit (HA), Cai0(PO4)6(OH)2, c mu trng, trng ng, vng nht hoc xanh l, tu theo iu kin hnh thnh, kch thc ht v trng thi tp hp. HA c nhit nng chy 1760c v nhit si 2850c, tan trong nc 0,7g/l, khi lng mol phn t 1004,60g, khi lng ring l 3,156g/cm3, cng theo thang Mohs bng 5.Cc tinh th HA t nhin v nhn to thng tn ti dng hnh que, hnh kim, hnh vy,... [29]. S dng phng php hin vi in t SEM hoc TEM c th nhn bit c cc dng tn ti ca tinh th HA (Hnh 1.1).

8221 I2KU X40,000 eenm uo 6

Hnh 1.1: Anh hiu vi iu t ca cc tnh th HA (a) - Dng hnh que(b) - Dng hnh tr(c) - Dng hnh cu(d) - Dng hnh si(e) - Dng hnh vy(f) - Dng hnh kimHA tn ti hai dng cu trc l dng lc phng (hexagonal) v dng n t (monoclinic). HA dng lc phng thng c to thnh trong qu trnh iu ch nhit t 25 n 100c, cn dng n t ch yu c sinh

ra khi nung dng lc phng 850c trong khng kh sau lm ngui n nhit phng. Gin nhiu x tia X ca hai dng ny ging nhau hon ton v s lng v v tr ca cc vch nhiu x. Chng ch khc nhau v cng ca pic, dng n t cho cc pic c cng yu hn cc pic ca dng lc phng khong 1% [14].Cu trc mng c s ca tinh th HA gm cc ion Ca2+, PO43' v OH' c sp xp nh hnh 1.2a. 0 mng ny c dng hnh lc phng , thuc nhm khng gian P63/1T1 vi cc hng s mng a = 0,9417nm, b = 0,9417nm v c = 0,6875nm, a = p = 90 v = 120 [30]. y l cu trc thng gp ca HA tng hp, trong thnh phn ca xng v ng rng [31].

Hnh 1.2: Cu trc mng c s ca tinh th HA men rng, cc tinh th HA sp xp rt c kht vi nhau bi cc mng c s thuc h n t, nhm khng gian P2 i/b (hnh 1.2b). Cc hng s mng ln lt c gi tr: a = 0,9421 nm, b = 1,8843nm v c = 0,688lnm, a = p = 90 vy= 120 [32].Cng thc cu to ca phn t HA c the hin trn hnh 1.3, c th nhn thy phn t HA c cu trc mch thng, cc lin kt Ca - o l lin kt cng ho tr. Hai nhm OH c gn vi hai nguyn t p hai u mch [35]:-4-

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Hnh 1.3 : Cng thc cu to ca phn t HA1.1.2. Tnh cht ho hc HA khng phn ng vi kim nhng phn ng vi axit to thnh cc mui canxi v nc:Cai0(PO4)6(OH)2 + 2HC1 3Ca3(P04)2 + CaCl2 + 2H20(1.1) HA tng i bn nhit, b phn hu chm trong khong nhit t 800c n 1200c to thnh oxy-hydroxyapatit theo phn ng:Ca10(PO4)6(OH)2 -> Ca10(PO4)6(OH)2.2xOx + xH20 (0 < X < 1)(1.2) nhit ln hn 1200c, HA b phn hu thnh 3 - Ca3(P04)2 (p TCP) v Ca4P209 hoc CaO:Ca10(PO4)6(OH)2 ^23 - Ca3(P04)2 + Ca4p209 + H20(1.3)Ca10(PO4)6(OH)2 ^3P - Ca3(P04)2 + CaO + H20(1.4)1.1.3. Tnh cht sinhhc [35] Nh trnh by trn, do c cng bn cht v thnh phn hohc, HA t nhin v nhn to u l nhng vt liu c tnh tng thch sinh hc cao. dng bt mn kch thc nano, HA l dng canxi photphat d c c th hp th nht vi t l Ca/P trong phn t' ng nh t l trong xng v rng, dng mng vdng xp, HA c thnh phnhohcvcc ctnhging xng t nhin,cc l xp lin thng vi nhaulmchoccm si,mch mu d dng xm nhp. Chnh v vy m vt liu ny c tnh tng thch sinh hc cao vi cc t bo v m, c tnh dn xng tt, to lin kt trc tip vi xng non dn n s ti sinh xng nhanh m khng b c th -#-

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o thi. Ngoi ra, HA l hp cht khng gy c, khng gy d ng cho c th ngi v c tnh st khun cao. Hp cht HA tng i bn vi dch men tiu ho, t chu nh hng ca dung dch axit trong d dy. dng bt mn kch thc nano, HA c c th ngi hp th rt nhanh qua nim mc li v thc qun. V nhng c tnh ny, bt HA kch thc nano c dng lm thuc b sung canxi vi hiu qu cao.e ch to vt liu HA c tnh tng thch sinh hc cao, cn nghin cu v chn la cc thng s cng ngh ph hp vi mi mc ch ng dng trong y sinh hc v dc hc.1.2. Vai tr v ng dng ca HAXng l phn quan trng ca c th ngi, c ngha to ln v mt sinh hc v cu trc, v mt sinh hc, xng l ni tp trung canxi nhiu nht v l ni sn xut cc t bo mu. Cn v mt cu trc, xng l khung cho cc b phn khc, hnh thnh nn kin trc v hnh dng c th. Cht khong trong xng gm ch yu l HA dng khi xp v mt s cht cha Na+, K+, Mg2+, cr, F", CO32" [38],[39].Khi mi sinh ra, xng c t l collagen nhiu v t l khong t. Cng ln ln, t l khong cng tng ln, xng cng tr nn gin, d gy. Trong xng ngi tr tui th cc pha v nh hnh chim u th v ch c mt phn chuyn ho thnh pha tinh th, cn ngi trng thnh th n 70% khi lng ca xng l HA. HA c vi cu trc l cc si tinh th di khong 10 -7- 15nm kt thnh b xp vi xp t' 40 -7- 60% gm cc mao qun thng nhau to ra phn khung ca xng [7]. Do c hot tnh sinh hc, c kh nng tng thch vi cc cu trc xng v c tnh dn xng tt nn HA c th c dng ni ghp, thay th xng trong c th ngi. Cc phu thut ghp xng, chnh hnh t c nhiu thnh tu nh ng dng vt liu y sinh HA.Mt vn ln khc i vi y hc th gii l cn bnh long xng. Mc d khng gy t vong nhng bnh long xng nh hng rt nhiu n cht lng cuc sng ca s ng ngi cao tui, c bit l ph n. Theo thng k ca T chc Y t Th gii (WHO), c n 1/3 ph n v 1/5 nam gii trn 50 tui b bnh long xng. D bo ti nm 2050, ton th gii s c ti 6,3 triu trng hp gy c xng i do long xng v 51% s ny s cc nc chu , ni m khu phn n hng ngy cn rt thiu canxi v vic chn on sm v iu tr tch cc bnh long xng cn gp rt nhiu kh khn. M, ngnh y t phi tiu tn hng nm khong 14 t USD iu tr cho 1,5 triu trng hp gy xng do bnh long xng gy ra [4]. Di y l mt s ng dng c th ca HA tu theo dng tn ti ca n.1.2.1. ng dng ca HA bt Do lng canxi hp th thc t t thc n mi ngy tng i thp nn rt cn b sung canxi cho c th, c bit cho tr em v ngi cao tui. Canxi c trong thc n hoc thuc thng nm dng hp cht ho tan nn kh nng hp th ca c th khng cao v thng phi dng kt hp vi vitamin D nhm tng cng vic hp th v chuyn ho canxi thnh HA. C th b sung canxi cho c th ngi bng cch dng thc n, thuc tim hoc truyn huyt thanh... Mt phng php hu hiu l s dng HA dng bt mn, kch thc nano b sung canxi [40]. Vi kch thc c 20 - lOOnm, HA c hp th trc tip vo c th m khng cn phi chuyn ho thm. Canxi dng ion c vai tr rt quan trng trong nhiu hot ng ca c th ngi nh tham gia vo qu trnh co c, dn truyn thn kinh, gii phng cc hooc mn v ng mu. Ngoi ra n cn tham gia vo qu trnh iu ho nhiu enzym khc nhau trong c th [9].

i vi bt HA c kch thc ht khong 150nm tr ln, qu trnh thiu kt to gm HA rt kh khn. Qu trnh kt khi din ra nhit kh cao (1000 - 1200C) trong thi gian di (2-3 gi), lm cho gm HA b phn hu thnh cc hp cht khng mong mun, c hi cho c the. Vi kch thc nano (t 20 - lOOnm), nhit kt khi ca HA bt gim xung ch cn khong 800 - 1000c trong thi gian t /4 gi n 1 gi. iu ny lm cho vic ch to gm y sinh hc t HA c cht lng cao, thun li v d dng hn.Hnh 1.4 l hnh nh ca mt s loi thc phm chc nng v thuc b sung canxi s dng nguyn liu HA bt dng vi tinh th ang c lun hnh trn th trng [40].LA RAY CalciumMroxyifutiwJorroui f ouuir IBONC-UP

CokiutnHydroxyopoMHnh 1.4: Thuc b sung canxi s dng nguyn liu HA dng vi tinh th1.2.2. ng dng ca HA dng mngThng thng, ngi ta s dng cc vt liu bn c - ho v nh thay th, sa cha nhng khuyt tt ca xng v rng. Ph bin nht l hp kim T6A14V, y l vt liu tr sinh hc v c bn c - ho cao nhng trong thc t n vn b n mn khi nm trong c th ngi, to ra cc cht c hi v lm cho lin kt gia xng v chi tit ghp b lng lo [42].Lp mng gm HA c chiu dy c im c ph ln b mt vt liu thay th bng cc phng php plasma, bc bay, in phn... hn ch nhng nhc im nu trn. Nhng bm dnh ca lp mng trn vt liu

nn khng bn cht, do vy tui th v phm vi ng dng ca chng khng cao [43]e ci thin bm dnh, ngi ta ph ln cc kim loi v hp kim nn mt lp mng gm HA c chiu dy c nanomet (mng n - HA) bng phng php in ho ni chung v phng php in di (Electrophoretic Deposition, EPD). Lp mng n - HA c bm dnh cao vi vt liu nn (> 60MPa) v rt bn theo thi gian. Cng ngh mng n - HA to ra nhng chi tit xng nhn to c kh nng t lin kt vi xng v m t nhin, c tnh tng thch sinh hc cao vi c th con ngi.Bng nhng tin b trong vic to mng n - HA, ngi ta khng ch lm tng tui th cc chi tit ghp m cn m rng phm vi ng dng ca mng n HA t ch ch p dng cho ghp xng hng tin n c th ng dng ghp xng i, xng khp gi v cc sa cha, thay th xng v tr khc.1.2.3. ng dng ca HA dng xpNh trnh by trn, vt liu gm xp HA c tnh tng thch sinh hc cao, c nhiu l lin thng vi nhau, to thun li cho s xm nhp ca m si v mch mu, c tnh dung np tt, khng c, khng d ng. Nh c kh nng c bit ny m ngy nay, HA dng gm xp c ng dng c bit rng ri trong y sinh hc nh: Ch to rng gi v sa cha nhng khuyt tt ca rng: cc nh khoa hoc Nht Bn thnh cng trong vic to ra mt hn hp gm HA tinh th kch thc nano v polymer sinh hc c kh nng ph v bm dnh trn rng theo c ch epitaxy, ngha l tinh th HA mi to thnh lp men rng cng chc, bt chc theo ng tinh th HA ca lp men rng t nhin di [45].

Hnh 1.5:Qu trnh to lp men HA trn b mt rngGiai on a: Lp men HA c, cn thay th trn b mt rng b phn hu bi dung dch H202 + H3PO4. Hp cht H202 cn c tc dng loi b cc cht bn tn ti trn rng.Giai on b: Cc ion Ca2+, P043, OH' trong cc polime sinh hc dng bt nho to thnh vi tinh th HA kch thc nano. Hn hp ny c ph ln b mt rng c to thnh lp men rng mi. Ch to mt gi [46]:

Hnh 1.6: HA xp tng hp t san h c s dng lm mt gi HA xp tng hp t san h c cu trc xp bn vng, nh v c bit l c kh nng thch ng cao vi c th. Vic s dng loi vt liu ny khc phc c hin tng sp mi do trng lng, hn ch cc phn ng ca c th v lm tng thi gian s dng ca mt gi [49]. Ch to nhng chi tit ghp xng v sa cha nhng khuyt tt ca xng [50]:

Hnh 1.7: Gm y sinh HA tng hp bng cc phng php khc nhau Tu thuc vo mc ch cy ghp hoc thay th, ngi ta c th ch to ra cc sn phm gm HA (Hnh 1.7) c kch thc v xp khc nhau [51]. Sau , gia cng cc sn phm ny thnh cc chi tit ph hp hoc c th s dng gm HA dng ht in y nhng ch khuyt tt ca xng [35].

Hnh 1.8: Sa cha khuyt tt ca xng bng gm HA dng khi xp hoc dng htNgoi ra, cn c mt s ng dng ca gm HA nh: Lm in cc sinh hc cho th nghim sinh hc [52]. Lm vt liu truyn dn v nh chm thuc [54]. Gn y, ngi ta pht hin HA dng xp c kh nng vn chuyn v phn tn insulin trong rut [55].Tuy nhin, gm HA cn c mt nhc im l bn nn, bn un thp. Tn ti ny cn tr vic p dng gm HA vo cc chi tit i hi chu lc ln.1.2.4. ng dng ca HA dng compostBn cht ca gm xp v mng HA l c bn c hc thp. Mt gii php tng bn c hc l to ra mt t hp gm composit bng cch phn tn HA bt vo cc polyme sinh hc nh collagen, chitosan, xenlulo, ng sacaro... [51]. Vt liu dng ny c s dng lm cc chi tit cy ghp xng cht lng cao, lm kp ni xng hoc c th lm cht truyn dn thuc. Vic s dng cc polyme sinh hc lm cht nn to iu kin cho vic gia cng, ch to cc chi tit d dng hn. Mt khc, cc polyme ny cn c kh nng lin kt vi cc t bo sinh hc thng qua cc nhm chc ca mnh. y cng l u im vt tri ca vt liu composit cha HA [58].1.3. Tnh hnh nghin cu vt liu HA1.3.1 Trn th giiCng vi s tin b ca khoa hc k thut, cc nh khoa hc nghin cu nhiu phng php khc nhau ch to HA nh: dng bt c iu ch bng phng php sol - gel [59], kt ta [60], phun sy [61], siu m [20]...; dng mng - bng phng php vt l [62] hoc in ho [63]...; dng khi rn, khi xp, vt liu t hp (composit) - bng phng php nn p - thiu kt HA bt [6], phn ng pha rn, phn ng thu nhit... [58].Hin nay, trn th gii sn xut c nhiu ch phm t nguyn liu HA. Nm 1983, Klein v cc ng nghip ln u tin to ra chi tit ghp xng bng gm cha 100% HA [67]. Thc t cho thy, s pht trin ca xng trong ming ghp ny c tc pht trin chm. iu ny to cho cht lng ca xng ni cy ghp rt tt, nhng thi gian iu tr ko di. Bng nhng th nghim khc, h cy ghp cc chi tit gm cha 100% p - TCP. Ket qu cho thy, tc pht trin ca xng non trong ming ghp rt nhanh, do vy lm cho cht lng ca xng ni cy ghp khng tt cho qu trnh pht trin ca xng.-9-

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Nm 1986, Moore v Chapman ch to c ming ghp t hp gia hai pha HA v p -TCP. Trong thc t, gm HA tt bao gm khong 93 - 94% HA v 6 - 7% TCP. TCP c hai dng th hnh l a v p -TCP, thnh phn a - TCP c tc dng lm tng tc ti sinh xng, n nh l ngun khong cung cp trc tip cho ch pht trin xng mi. iu ny c ngha rng phn p -TCP s tiu bin dn nh l ngun cung cp khong cho xng non pht trin vo ch khuyt xng. Do gm t hp HA - p - TCP l vt liu y sinh chnh cho cc phu thut ghp xng, ni xng, chnh hnh hoc sa cha xng. cha tr cn bnh long xng, Cc Qun l Thc phm v Dc phm M (FDA) cho php s dng HA trong sn xut thuc v thc phm chc nng. Nhiu loi thuc v thc phm b sung canxi c s dng HA c lu hnh trn th trng. Trong s c th k n Ossopan ca Php, Bone Booster Complex, Bone Dense Calcium ca M, Calcium Complex ca Anh, SuperCal ca New Zealand [69].Nh trong phn ng dng cp, HA dng mng c cc nh khoa hc Nht Bn ch to thnh vt liu ch to rng gi v sa cha nhng khuyt tt ca rng.1.3.2 Nghin cu v ng dng HA ( Vit NamTrong nc, cc hp cht v c c kh nng ng dng lm vt liu sinh hc ni chung v HA ni ring cn nhiu hn ch.Nm 2005, ln u tin Vin Cng ngh X him trin khai ti ch th gm HA theo cng ngh ca Italia v bc u th nghim thnh cng trn ng vt [3]. Cng ngh ny da trn phng php nhng tm khung xp hu c xenlul vo dung dch huyn ph HA, sau nung thiu kt nhit cao. Khoa Ho hc, i hc Bch khoa H Ni nghin cu v cng b kt qu s b v phng php tng hp bt v mng gm HA [6].T nm 2005 n nay, Vin Ho hc, Vin Khoa hc v Cng ngh Vit Nam cng b mt s kt qu nghin cu ch to HA bt [5] v HA xp [27]. Trong HA xp c ch to bng phng php nn p - thiu kt HA bt vi cc cht to xp chitosan, xenlulo, ng sacaro v phng php phn ng pha rn gia Ca(OH)2 v Ca3(P04)2. Vic ch to gm HA t khung xp t nhin ca san h, mai mc, v s... bng phn ng thu nhit p sut cao cng c thc hin.Nm 2008, Trung tm Pht trin Khoa hc v Cng ngh Tr nghin cu ti Nghin cu ch to gom sinh hc Cacium phosphate: Hydroxyapatite Cai0(PO4)(OH)2(HA) v Tricalicium phosphate Cas(P04)2(TCP), ng dng thay th mt s b phn xng, khp trong c th con ngi.1.4. Cc phng php tng hp HATrn th gii, vic nghin cu ch to vt liu HA cc dng c trin khai t lu v t c nhng thnh tu ng k. Cc nghin cn tp trung vo tng hp HA dng bt mn v siu mn, dng khi xp, dng mng bng cc phng php khc nhau v kho st cc c tnh nng cao kh nng ng dng ca chng. Vic ng dng loi vt liu tin tin ny to ra nhng bc tin mi trong cc lnh vc: xt nghim, iu tr y hc cng nh trong dc phm v vt liu y sinh hc.Tu thuc vo mc ch ng dng, HA cc dng khc nhau c th c tng hp bng nhiu phng php t cc nguyn liu khc nhau. Da vo iu kin tin hnh phn ng, c th phn chia cc phng php thnh: phng php t v phng php kh; phng php vt l v phng php ho hc hoc chia theo dng tn ti (dng bt, dng mng, dng khi xp) ca sn phm HA. Trong lun vn ny chng ti trnh by cc cch ch to HA theo phng php t v phng php kh.

1.4.1. Phng php ty l phng php ch to HA dng bt hoc dng mng t dung dch cha cc nguyn liu ban u khc nhau, bao gm: phng php kt ta, phng php sol - gel, phng php phun sy... Ni chung, u im ca phng php t l c th iu chnh c kch thc ca ht HA theo mong mun.Trong h CaO - P2O5 - H20, tn ti cc hp cht canxi photphat khc nhau tu thuc vo t l ca cc cht ban u v iu kin p sut, nhit , pH... p dng cc quy tc pha vo gin pha CaO - P2O5 - H20, nm 1996, T. s. B. Narasaraju v D. E. Phebe [30] tin hnh nghin cu s to thnh ca cc pha khc nhau c trong h l: anhydric mono canxi photphat - Ca(H2H04)2, mono canxi photphat monohydrat- Ca(H2P04)2.H20. Trn hnh 1.9, c th nhn thy cc pha lng tn ti vng trng, cc pha rn nm vng elip cn li. Anhydric mono canxi photphat - Ca(H2P04)2 v cc mono hydrat ca n tn ti di dng tinh th trong vng axit, tc l vng c t l P2O5 cao. Anhydric icanxi photphat - CaHP04 tn ti vng axit, cn icanxi photphat ihyrat - CaHP04.2H20 lun tn ti trong mi trng phn ng c pH khc nhau.Hnh 1.9: Gin pha ca h CaO - P2O5 - H2O 25c

Trong khong t l Ca/P t 1,5 n 1,67 tng ng vi vng cha tricanxi photphat Ca3(P4)2 n vng cha tetracanxi photphat Ca3(P04)2.Ca0, xut hin cc tinh th Ca9(HP04)(P04)50H (Calcium Deficient HA, CDHA). vng kim ng vi t l Ca/P cao hn (ln hn 1,67), ch tn ti duy nht mt pha rn HA, hp cht hydroxyapatit tn ti pha rn ny c thnh phn ho hc theo ng t l hp thc Cai0(PO4)6(OH)2 (Ca/P = 1,67, Stoichiometric Hydroxyapatite - SHA).1.4.1.1. Phng php kt taS nguyn l ca phng php kt ta c th hin qua hnh 1.10:

Hnh 1.10: S nguyn l ca phng php kt taVic tng hp HA bng cch kt ta t cc ion Ca2+ v PO43' c th thc hin theo nhiu cch khc nhau, c th phn ra thnh hai nhm chnh:a) Phng php kt ta t cc mui cha ion Ca2+v PO~ d tan trong nc:Cc mui hay c dng l Ca(N03)2, CaCl2, (NH4)2HP04, NH4H2PO4... [24]. Phn ng din ra theo phng trnh (1.5) c coi l phng php c bn tng hp HA [60]: 10Ca(N03)2 + 6(NH4)2HP04 + 8NH4OH -> Ca,o(P04)6(OH)2 + 2ONH4NO3 + 6H2O (1.5) Lng Ca(N03)2 v (NH4)2HP04 c chun b theo t l Ca/P = 1,67, pha trong nc ct vi nng tng ng 0,2M v 0,1M. Sau , nh t t (tc 2ml/pht) dung dch (NH4)2HP04 vo cc ng Ca(N03)2 trn my khuy t (tc 300 - 400 vng/pht). B sung dung dch NH4OH m bo phn ng din ra trong mi trng pH = 10 - 12.Sau khi nh ht lng dung dch (NH4)2HP04 tip tc khuy hn hp trong khong 2 gi ti nhit nh. Ket thc phn ng, thu ly kt ta v lm sch bng cch lc ra nhiu ln vi nc ct trn my ly tm hoc thit b lc ht chn khng. Sn phm c sy kh nhit 75 - 80c v bo qun trnh tip xc vi khng kh.b) Phng php kt ta t cc hp cht cha Ca2+ t tan hoc khng tan trong nc:Phn ng xy ra gia Ca(OH)2, CaO, CaC3... vi axit H3PO4 trong mi trng kim [28]. V d:1 OCa(OH)2 + 6H3PO4 = Ca10(PO4)6(OH)2 + 18H20(1.6)Trong qu trnh iu ch, yu t pH cng ng vai tr quan trng. pH 9-10 c iu chnh bng cch thm t t H3PO4 vo Ca(OH)2.Cc yu t nh nguyn liu ban u, nhit , mi trng phn ng... thng nh hng n cht lng v hnh dng ca tinh th HA. e nhn c sn phm HA bt c kch thc mong mun th ngoi cc yu t trn, cn quan tm n s kt tinh ca HA trong sut qu trnh tng hp.1.4.1.2. Phng php sol - gel [10], [59], [15]Theo l thuyt v phng php sol - gel, h phn tn l h bao gm mt mi trng lin tc v cc tiu phn (cc ht) c kch thc nh c phn tn ng u trong mi trng . Tp hp cc tiu phn nh b c gi l pha phn tn, mi trng cha ng pha phn tn gi l mi trng phntn. Khi mi trng phn tn l lng v pha phn tn l rn, th tu kch thc ht s to ra h huyn ph hoc h keo (sol).Gel l mt trng thi lng ho rn, c to thnh t' cc h sol hoc cc dung dch cao phn t. Gel c cu trc mng khng gian cha ng trong n phn cn li ca cht lng sau khi hnh thnh mng. Qu trnh to gel c m t nh sau: H sol, dung dch cao phn t gel, ngha l cc h sol, dung dch cao phn t c th chuyn thnh gel hoc ngc li tu thuc iu kin. Cc yu t nh hng n qu trnh to gel l: kch thc, hnh dng ca ht keo v cht cao phn t; nng pha phn tn v cht cao phn t; nng cht in ly, nhit , cng v thi gian khuy...C th chuyn sol thnh gel bng cch tch dung mi. Khi dung mi b tch ra, cc ht keo hoc cht cao phn t li gn nhau hn, to iu kin thun li cho chng ni cho vi nhau. Khi s ni cho ny ln, nht ca dung dch tng nhanh v ton b khi dung dch s chuyn thnh gel. Cng c th dng cch khuy mnh dung dch to gel. Cng v thi gian khuy ln s lm tng tn s va chm gia cc ht keo v to iu kin cho chng ni cho vi nhau. Trong thc t, thng kt hp c hai cch trn chuyn sol thnh gel.u im ca phng php sol - gel l to c ng nht cao mc phn t, t c th ch to vt liu dng khi, mng mng [70], si v dng ht c cht lng tt [15].S nguyn l ca phng php sol - gel c th hin qua hnh sau:

Hnh .l 1: S nguyn l ca phng php sol - gel

C th tng hp HA theo phng php sol - gel bng cch: ho tan cc hp cht Ca(N3)2, (NH4)2HP04 vi cc cht to gel nh (C2H50)3P(0), CH30(CH2)2(OH) (c chun b theo t l nht nh) vo nc ct. Khuy v gia nhit dung dch ny n nhit 60 - 70c, sau khong 3-4 gi, gel c cha hp cht HA s c to thnh. Sau , sy gel nhit khong 120c trong vng 24 gi v nung nhit 750 - 900c khong 1 gi. HA bt nhn c c kch thc trung bnh khong 20nm, tinh th khong 97% [59].1.4.1.3. Phng php phun syHnh 1.12 l s nguyn l ca phng php phun sy. Dung dch cha cc ion Ca2+ v P043 (t l Ca/P = 1,67) c phun vo thit b cng vi kh nn.

Tc phun dung dch c iu chnh bng p sut kh nn v dng kh kh sao cho phn ng to HA xy ra hon ton, bt HA c sy kh khi ri n y ca ct thu tinh gia nhit. Sn phm HA dng bt c ly ra nh k qua b phn lng tnh in. y l phng php ch to bt HA dng lin tc, nng sut cao, ph hp vi quy m sn xut va v ln [61].

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1.4.1.4 Phng php siu m ho hcTrong thc t, ch to HA bt c kch thc siu mn, c th tin hnh phn ng ho hc trong mi trng sng c cng ln nh vi sng [34] hay sng siu m [20].Nguyn l ca phng php siu m da vo hin tng to v v bt (cavitation) xy ra trong mi trng lng di tc dng ca sng siu m vi cng cao. Sng siu m to ra mt chu trnh gin n, n gy ra p sut chn khng trong mi trng lng. Hin tng to - v bt xy ra khi p sut chn khng vt qu so vi bn ko ca cht lng. Khi bt pht trin ti kch thc no , khng hp thu nng lng c na th di p lc t cht lng bn ngoi, bt s v vo trong (hnh 1.13). Hin tng ny sinh ra mt lng nhit ti ngay thi im gi l s to nhit im (host - spot). Tuy nhin, mi trng lng xung quanh c nhit thp nn s gia nhit nhanh chng c dp tt. im to nhit c nhit v p sut cao, thi gian sng ca n rt ngn. Qu trnh to v v bt ng vai tr nhn v tp trung nng lng ca sng siu m, chuyn nng lng ny thnh nng lng cn thit lm tng tc phn ng ho hc ln nhiu ln.

Hnh 1.13: Qu trnh to v v bt di tc dng ca sng siu m Nng lng c to ra dng xung vi cng rt ln cng lm tng tc to mm tinh th. Qu trnh to - v bt tip tc xy ra gn b mt phn pha lng - rn, lc ny cht lng tc ng ln b mt cht rn vi tc rt cao. Tu thuc vo tn s v cng sut ca thit b siu m, c th lm cho cc tinh th b v thnh nhng ht nh hn.Hnh 1.14 l s nguyn l ca phng php siu m ho hc. u pht siu m c ngm vo trong dung dch truyn nng lng cho phn ng ho hc. Phng php ny thng c kt hp vi phng php kt ta to HA bt c kch thc nanomet [15].

Hnh 1.14: S nguyn l ca phng php siu m ho hc1.4.1.5. Phng php compositPhng php composit c s dng ch to cc vt liu dng khi xp cha HA. HA c s dng thng dng ht, cht nn l cc phn t polyme. S kt hp ca ht HA vi polyme a ra mt phng thc n gin v hu hiu gn kt cc c tnh ca hai loi vt liu. C th s dng cc polyme nh axit polylactic, polystyren, polyethylen, Collagen, chitosan, xenlulo... trong cc polyme sinh hc c c bit quan tm trong lnh vc y sinh v chng c tnh tng thch v phn hu sinh hc cao. ch to vt liu composit cha HA, cation Ca2+ c phn tn u trong mng li polyme sau cc anion PO43" v OH c a vo di dng dung dch phn ng to thnh cc nano tinh th. Cng c th thc hin phn ng to ra cc tinh th nano HA trc, sau phn tn chng vo mng li polyme nhm ngn khng cho cc tinh th HA kct khi li vi nhau. Vic s dng cc polyme sinh hc lm cht nn to iu kin cho vic gia cng, ch to cc chi tit d dng hn. Mt khc cc polyme ny cn c kh nng lin kt vi cc t bo sinh hc thng qua cc nhm chc ca mnh. y cng l un im vt tri ca vt liu composit cha HA.V d, c th tm tt qu trnh tng hp HA bng phng php composit vi chitosan (CS) theo s sau [36]:

Hnh 1.15: S tng hp composit HA - cs

Theo [36], khi t l CS/HA tng ln th s phn tn cc ht HA vo mng cs s tt hn, do kch thc ca cc ht HA phn tn s nh hn, ng thi kt tinh ca HA cng tng ln.1.4.1.6. Phng php in ho Vi nhng vt liu truyn thng, ngnh phu thut chnh hnh thng s dng cc kim loi tr sinh hc nh titan, thp khng g hay cc hp kim thay th hay ni ghp cc b phn ca xng. Mc d cc kim loi ny c bn cao nhng khng c kh nng tng thch sinh hc, b n mn theo thi -20-

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gian nn cc m t bo khng c kh nng pht trin trn cc kim loi . Cc bnh nhn s cm thy au n v kh chu khi c nhng vt l nm trong c th. e tng cng, bn c - ho v tnh tng thch sinh hc ca chi tit cy ghp, ngi ta ch to lp mng gm HA c dy mong mun v c kh nng bm dnh tt trn b mt kim loi.Bng cc phng php vt l nh plasma, bay bc, h quang... u to ra mt lp mng c chiu dy c |0,m. bm dnh ca lp mng ny vo vt liu nn khng cao, thng dao ng t 15 - 30MPa, trong khi yu cu ti thiu phi t khong 50MPa mi m bo tui th v trnh s thoi ho sm ca vt liu ghp.e khc phc hn ch ny, ngi ta ch to v ph c lp mng HA c chiu dy c nanommet (mng n - HA) trn cc vt liu nn khc nhau bng: Phng php kt ta catot:Nguyn tc ca phng php l s dng cc vt liu sinh hc bng kim loi hoc hp kim lm in cc catot, in cc ny c nhng vo b in phn vi cht in gii l dung dch bo ho cc ion Ca2+ v P043' pH = 6. Qu trnh catot ho din ra th phn cc ti catot so vi calomen bo ho l -2V, mt dng catot t lOmA/cm2, nhit in phn c duy tr 60c. Lp mng HA c to ra trn vt liu nn c chiu dy khong lOOnm trong vng 10 pht, chiu dy ca lp mng HA tng theo thi gian catot ho [41], [63]. Phng php anot ho: Nguyn tc ca phng php ny l s dng cc vt liu sinh hc bng kim loi hoc hp kim lm in cc anot. Catot c lm bng kim loi tr, chang hn nh bch kim. H in cc c a vo dung dch in gii cha cc ion Ca2+ v PO43 theo t l Ca/P = 1,67. Di tc dng ca in p mt chiu t 250 - 350V, trn anot s xy ra hin tng phng tia la in ti cc im dn in tt. Ti ni ny nhit c th ln n 103- 104 Kenvin lm cho kim loi b oxi ho, cc oxit to thnh b nng chy to thnh mt lp oxit vi chiu dy khong 1 - 2jam c xp cao. Lp oxit ny c in tr ln khi ngui v ng rn, lm cho hin tng phng tia la in chuyn sang im c in tr nh hn. Thi gian anot ho din ra trong khong 30 pht to ra mt khi oxit c xp cao. Ti cc mao qun ca khi xp ny s xy ra hin tng hp th cc ion Ca2+ v P043\ Qu trnh hnh thnh cc tinh th HA ph thuc vo s lng cc mm tinh th trong khi phng in v s khuch tn ca cc ion Ca2+ v P043 n b mt lp oxit [37]. Phng php in di (EPD'): Da trn hin tng chuyn dch tng i ca pha phn tn trong mi trng phn tn di tc dng ca in trng ngoi [8.H]. Pha phn tn l cc ht HA kch thc nanomet, mi trng phn tn c th l nc hoc mi trng m phng dch th ngi SBF (Simulated Body Fluid). Di tc dng ca in trng ph hp, cc ht huyn ph HA tch in m v di chuyn v pha anot (gn vt liu nn) to ra mt lp mng mng n - HA (mng HA c dy c nanomet) trn b mt chi tit vi bm dnh cao [41].

Phng php in di to c lp mng n - HA c bm dnh tt, ln hn 60MPa, dng t n mn chy qua mng n - HA nh hn 300 ln so vi dng t n mn ca mng jLi - HA (mng HA c dy c |0,m).1.4.1.7. Phng php thu nhit (hoc nhit)Phng php ny c dng ch yu ch to HA xp v gm xp. Nhn chung, sn phm HA thu c vn gi nguyn hnh thi v cu trc xp ging nh khung xng t' nhin ca ng vt thn mm ban u (san h, mai mc, v trai, v c...). Vi cu trc xp sinh hc nh vy, vt liu ny c kh nng tng thch sinh hc vi c th con ngi tt hn so vi gm xp HA tng hp bng nhng phng php khc [68].Khung xng ca cc ng vt thn mm (san h, mai mc, v s...) c thnh phn ch yu (hn 98%) l CaC03 dng aragonit. Phn ng thu nhit xy ra gia CaC03 vi dung dch (NH4)2HP04 trong thit b kn autoclave, c gia nhit. Do mai mc c xp rt cao, din tch b mt ln nn phn ng d th xy ra ch cn duy tr trong khong nhit 150 - 250c p sut 4 - 15atm, thi gian 24 - 30 gi [66]. Khung xp ca san h c cu to bi cc tinh th aragonit ln, sp xp c kht vi nhau do vy phn ng thu nhit to HA ch din ra nhit khong 200 - 300c, p sut rt cao, ln ti lOOOatm [44]. Phn ng thu nhit din ra theo phng trnh:10CaC03 + 6(NH4)2HP04 + 2H20 -> Ca10(PO4)6(OH)2 + 6(NH4)2C03 + 4H2CC>3 (1.7)Hnh 1.17 l s nguyn l ca h thit b phn ng thu nhit.

C th ch to HA xp t khung xng t nhin bng phn ng thu nhit thng qua sn phm trung gian CaO. Trc ht, chuyn ho khung xng CaC3 thnh CaO m vn gi nguyn hnh dng ban u. Sau , phn ng thu nhit theo phng trnh (1.7) c tin hnh trong h thit b nh hnh 1.17, nhit khong 200c, p sut 10 - 15atm, thi gian 24 - 48 gi:1 OCaO + 6(NH4)2HP04 + 4H20 Ca10(PO4)6(OH)2 + 12NH4OH (1.8) Qu trnh thu phn ca mui CaHP04 cng to ra sn phm HA trong bom thu nhit c bc lt bng platin hoc teflon nhit 250 - 300c, trong thi gian 5-10 ngy. Nhit v p sut cao to iu kin cho cc tinh th HA hnh thnh v pht trin. Phn ng xy ra nh sau [3]:10CaHP04 + 2H20 -> Caio(P04)6(OH)2 + 4H+ + 4H2P04'(1.9)14CaHP04 + 2H20 -> Ca10(PO4)6(OH)2 + 4Ca2+ + 8H2PO4'(1.10) iu kin trn, pha rn HA c kt tinh cao, sn phm thu c l n pha, nhng thit b v iu kin phn ng phc tp, kh thc hin.1.4.2. Phong php kh1.4.2.1. Phng php phn ng pha rny l phng php tng hp HA trn c s thc hin cc phn ng pha rn. Nguyn liu ban u c th l: Ca3(P04)2 v Ca4P209, Ca3(P04)2 v CaO,... c trn u theo t l Ca/P = 1,7, sau tin hnh phn ng nhit khong 1000c, trong h kn. Phn ng to HA din ra nh sau [65]: 2Ca3(P04)2 + Ca4p209 + H20 -> Ca10(PO4)6(OH)2(1.11)3Ca3(P04)2 + CaO + H20 -> Ca10(PO4)6(OH)2(1.12)Nhc im ca phng php ny l cn thc hin nhit v p sut cao trong thi gian di.Cng c the ch to HA bt v khi xp bng phn ng pha rn gia Ca3(P04)2 v Ca(OH)2 nhit thp (250 - 300C) trong p sut kh quyn: 3Ca3(P04)2 + Ca(OH)2 -> Ca10(PO4)6(OH)2(1.13)Cc phn ng pha rn ny thng c p dng ch to HA dng khi xp. Hn hp nguyn liu rn ban u c p nn to ra cc chi tit c hnh dng v xp mong mun. Sau phn ng, sn phm vn gi nguyn c hnh dng v cu trc xp ban u. Chnh nh nhng u im ny m phng php phn ng pha rn ny thch hp cho vic ch to gom y sinh vi cc chi tit phc tp.1.4.2.2. Phng php ho - c [65Bng phng php ho - c, c th ch to HA bt bng phn ng gia hai pha rn CaC03 v CaHP04.2H20:4CaC03+ 6CaHP04.2H20 -> Caio(P04)6(OH)2 + 4H2C03 (1.14)Hoc bng cc phn ng sau:2Ca3(P04)2 + Ca4P209 + H20 -> Ca10(PO4)6(OH)2(1.15)2Ca3(P04)2 + CaO + H20 -* Ca10(PO4)6(OH)2(1.16)Nguyn l ca phng php ny l tc ng mt lc ma st ln gia bi v m nghin ca bi n cc cu t ca hai pha rn. Lc ny cn phi mnh to ra s khuch tn ni, tin ti phn ng ho hc gia hai pha rn to ra pha rn th ba. Qu trnh phn ng xy ra trong thit b nghin vi m nghin v bi c cng cao, khi lng ring ca bi ln.u im ca phng php l iu kin phn ng n gin, d thc hin. Nhc im l thi gian phn ng di, sn phm HA nhn c d b ln tp cht do s mi mn ca bi v m nghin.1.4.2.3. Mt s phng php vt lNgoi cc phng php trn, cn c mt s phng php vt l nh phng php plasma, bc bay chn khng, phn x magnetron, h quang... ch to mng gm HA trn cc vt liu nn tr sinh hc [25]. Nguyn l ca cc phng php ny l lm bc bay cc phn t HA nhit cao trong chn khng, sau tch t li trn tr sinh hc.Bng cc phng php trn c th d dng ch to c mng HA c chiu dy c xm. Mng HA c bm dnh tng i cao vi vt liu nn, nhng kh to ra cc mng rt mng (chiu dy c nm), kh iu chnh c dy ca lp mng. Mt khc, do thc hin nhit cao, HA d b phn hu do nhit cao dn n t l Ca/P thay i, nn sn phm thng ln cc tp cht ca vt liu nn. Phng php plasma:Hnh 1.18 l s nguyn l ca phng php plasma. Bt HA b ion ho v mt phn nng chy trong dng plasma, to ra mt lp mng bm trn vt liu nn tng i bn [42], [62].

Hnh 1.18: S nguyn ca phng php pasma Phng php bc bay chn khng [11]:ung chn khng\Thuyn in trThit b ht chn khng cao(l t)

Gi gn mu v l t nng Cm bin o chiu dy Vt liu nn HA bay hoiHAHnh 1.19: S nguyn l ca phorig php bc bay chn khngB phn chnh ca thit b bc bay nhit l mt bung c ht chn khng cao (c 105 - 10~6Torr) nh cc bm chn khng (bm khuch tn hoc bm phn t...). Thuyn in tr c lm bng cc vt liu (vonphram, tantan, bch kim...) chu nhit v t tng tc vi HA, c nhim v t nng chy HA cho n khi HA bay hi. Sau HA s ngng ng ln cc c gn vo gi pha trn (hnh 1.19). Phng php phn x magnetron:Hnh 1.20 l s nguyn l ca phng php phn x magnetron. Nguyn l ca phng php l s dng ngun pht to trng in t' tn s cao (13,56 MHz) [42].

r-1!Wif \M-iA, /4, op .*opn>a> 0 V / : ;% . o1h0ip .. ii.of\j -tA var MKj r*r\Scfwmar?k: Juktrwn lUwotrotnr mapneucfiIIMnrp %vtnHnh 1.20: S nguyn l ca phng php phn x magnetron Do electron c khi lng nh hn nhiu so vi ion dng, nn dng xoay chiu ny ch lm dch chuyn electron, cn ion dng khng b nh hng nhiu. Electron di chuyn s va chm vi Ar trung ho v sinh ra ion Ar+. Cc ht kh ion ny c gia tc v va chm vi cc nguyn t trn b mt ca HA, lm cho chng phn x v bay n vt liu nn, lng ng hnh thnh nn lp mng HA [12].1.5. Mt s phoig php nghin cu vt liu HA1.5.1. Phtmg php nhiu x tia X (X - Ray Diffraction, XRD) Phng php XRD c dng nghin cu cu trc tinh th ca vt liu, c th xc nh nhanh, chnh xc cc pha tinh th, nh lng pha tinh th v kch thc ht vi tin cy cao.Nguyn l ca phng php l xc nh cu trc tinh th da vo hnh nh khc nhau ca kch thc tinh th ln ph nhiu x. Mng tinh th nguyn t hay ion phn b u n trong khng gian theo mt trt t nht nh. Khong cch gia cc nt mng vo khong vi ngstron (A) xp x vi bc sng ca tia Rnghen.Mt chm electron c gia tc, c nng lng cao, ang chuyn ng nhanh, b hm t ngt bng mt vt cn, mt phn nng lng ca chng chuyn thnh bc x sng in t' (tia X) gi l bc x hm.Khi mt chm tia X c bc sng X v cng I i qua vt liu, nu tia ti thay i phng truyn v thay i nng lng gi l tn x khng n hi. Khi tia ti thay i phng truyn nhng khng thay i nng lng gi l tn x n hi. Trng hp vt liu ang nghin cu c cu trc tinh th th hin tng tn x n hi ca tia X s a n hin tng nhiu x tia X. Hin tng ny ch xy ra vi ba iu kin: Vt liu c cu trc tinh th; c tn x n hi; bc sng ca tia X (tia ti) c gi tr cng bc vi khong cch gia cc nguyn t trong mng tinh th.

Hnh 1.21: S nguyn l ca phng php nhiu x tia X Trong mng li tinh th lun tn ti h cc mt phang song song, cch u nhau mt khong bng d. Mt chm tia X c bc sng X chiu ti b mt ca mng li tinh th vi mt gc 0 s b phn x tr li (hnh 1.21). Tt c cc tia phn x to nn chm tia X song song c cng mt bc sng v c phng truyn lm vi phng tia ti mt gc 20. Khi hiu s pha gia cc tia X phn x l 2\n (n l s nguyn), ti im hi t chm tia X s c vn giao thoa vi cng nh sng cc i.Cc nguyn t, ion ny c phn b u trn cc mt phng song song, do vy hiu quang trnh ca hai tia phn x bt k trn hai mt phang song song cnh nhau c tnh bng cng thc: = 2.d.sin0(1.17)Trong , d l khong cch gia hai mt song song, 9 l gc gia chm tia X v mt phng phn x, A l hiu quang trnh ca hai tia phn x.T hnh 1.21 cho thy, hiu quang trnh gia hai tia bng 2.d.sin0. Bragg biu din iu kin c hin tng nhiu x bng phng trnh:2.d.sin0 = n(1-18)Trong , d l khong cch gia hai mt song song, 0 l gc gia chm tia X, n l bc phn x (s nguyn dng), X l bc sng ca tia ti.y l phng trnh c s nghin cn cu trc mng tinh th. Cn c vo gi tr cc i trn gin (gi tr 29) c th tnh c d theo phng trnh (1.18). Bng phng php ny s xc nh c cu trc mng tinh th ca cht cn nghin cu.Ngoi vic xc nh cu trc, XRD cn cho php xc nh kch thc ca tinh th. Bn cht vt l ca vic xc nh kch thc tinh th bng phng php XRD l: kch thc ht v rng ca vch nhiu x c mi lin h ph thuc. Mu c cc ht vi kch thc ln th rng vch nhiu x b v ngc li. Scherrer a ra cng thc tnh ton kch thc tinh th trung bnh ca tinh th theo phng trnh:^ kXD = i^ D l kch thc tinh th trung bnh (nm), 0 l gc nhiu x, B l rng pic c trng (radian) cao bng na cng cc i (ti v tr gc 20 = 25,88, i vi HA), X = 1,5406A l bc sng ca tia ti, k l hng s Scherrer ph thuc vo hnh dng ca tinh th v ch s Miller ca vch nhiu x (i vi HA, k = 0,9) [47]. Trong phng trnh (1.19), kch thc ht D t -30-

-31-

l nghch vi rng B v c COS0 mu s, nn mun c gi tr D chnh xc cn s dng vch nhiu x tng ng vi gc 0 b.T gin XRD, tinh th c tnh ton theo phng php phn gii pic [48], theo cng thc:c = 100%(1.20)Trong :cl tinh th trong bt HAY l chiu cao ca pic c trng (vi HA, thng chn pic c ch s Miller 300)X l chiu cao chn pic ti v tr thp nht gia hai pic c ch s Miller 300 v 112)(300)

3132332-Tlieta

Hnh 1.22: Gin nhiu x tia X ca HA Hm lng pha Ca3(P04)2 trong bt HA c nh gi bng phng php XRD phn gii cao, vi gc quay 29 = 24 - 38. Hm lng cc pha c trong bt c tnh ton t' din tch cc pic c trung cho mi pha nh sau:%HA =100%(1.21)Sa + Sptrong , Sa l din tch ca pic c trung cho tinh th HA, Sp l din tch ca pic c trung cho tinh th Ca3(P04)2 [48], [53].

Hnh 1.23: Gin nhiu x tia Xca HA v TCP Gin XRD ca mu cn c ghi theo cng mt ch vi ph chun ATSM, sau kt qu o c so snh vi d liu ATSM.1.5.2. Phong php ph hng ngoi (Fourier Transformation Infrared Spectrophotometer, FTIR)Ph hong ngoi dng xc nh cu trc phn t' ca cht cn nghin cu, da vo cc tn s c trng trn ph ca cc nhm chc trong phn t. Ph hng ngoi chnh l ph dao ng - quay v khi hp th bc x hng ngoi th c chuyn ng dao ng v chuyn ng quay ca cc nhm chc u b kch thch. Ph dao ng - quay ca phn t c pht sinh ra do s chuyn dch gia cc mc nng lng dao ng v quay (lin quan n s quay ca phn t xung quanh trc lin kt). Dng nng lng c sinh ra khi chuyn dch gia cc mc ny dng lng t ho, ngha l ch c th bin thin mt cch gin on. Hiu s nng lng (pht ra hay hp th) c tnh theo cng thc Bohr:AE = hvTrong , AE l bin thin nng lng, h l hang so Planck, V l tn s dao ng (s dao ng trong mt n v thi gian).Hnh 1.24 di y l s nguyn l ca my quang ph hng ngoi bin i Fourie (FTIR). Ngun bc x (1) pht ra mt chm tia hng ngoivi mt tn s trong vng cn o. Chm tia ny i qua b giao thoa k (gm gng c nh, gng di ng v b phn phn chia chm sng). Bc x hng ngoi sau khi i ra khi giao thoa k s i qua mu ri n detector. Detector ghi nhn s bin i ca cng ca bc x theo qung ng d m gng di ng thc hin c ri chuyn thnh tn hiu in. Khi , thu c tn hiu di dng hm ca in th V theo qung ng:v = f(d)My tnh s thc hin php bin i Fourie chuyn hm V = f(d) thnh hm ca cng bc x I theo nghch o ca qung ng d (d"[footnoteRef:1]). [1: - Ngun sng5 - Mau]

A\ bin i Fourie _ Kv = f(d) > I = f(d )V d1 chnh l s sng , do thc cht l hm ph thuc ca cng bc x vo s sng.6 7 8 Hnh 1.24: S nguyn l ca my quang pho hng ngoi35-""

Bng 1: Bc sng c trng ca cc nhm chc [3]Nhm chcBc sng (em'1)

H - 0 Stretch3570

c - o Stretch2345

p - 0 Str (H3PO4)1649

C032' Stretch1545- 1445

p - 0 Stretch1091

p - 0 Stretch962

H - 0 Bend632

0 - p - 0 Bend576

1.5.3. Phng php hin vi in t.5.3.1. Phng php hin vi in t' qut (Scanning Electron Microscopy, SEM) [57]Nguyn tc ca phng php hin vi in t qut l dng chm in t qut ln b mt mu v thu nhn li chm tia phn x. Qua vic x l chm tia phn x ny, c th thu c nhng thng tin v hnh nh b mt mu to nh ca mu nghin cu.Phng php knh hin vi in t qut cho php quan st mu vi phng i rt ln, t hng nghn n hng chc nghn ln.Chm in t c to ra t catot qua hai t quang s c hi t ln mu nghin cu. Chm in t p vo mu pht ra cc in t phn x th cp. Mi in t pht x ny qua in th gia tc vo phn thu v bin i thnh tn hiu sng, chng c khuch i a vo mng li iu khin to sng trn mn hnh.Mi dim trn mu nghin cu cho mt dim trn mn hnh. sng ti trn mn hnh ph thuc lng in t th cp pht ra ti b thu, ng thicn ph thuc b mt ca mu nghin cu. u im ca phng php SEM l c the thu c nhng bc nh ba chiu r nt v khng i hi khu chun b mu qu phc tp. Tuy nhin, phng php ny cho phng i nh hn phng php TEM.Hnh 1.25: S nguyn l ca SEM1.5.3.2. Phng php hin v in t truyn qua (Transmission Electron Microcopy, TEM) [8Nguyn tc ca knh hin vi in t truyn qua (TEM) l s dng chm in t xuyn qua mu cn nghin cu. Do vy, cc mu ny cn phi mong chm in t xuyn qua.

Hnh 1.26: Nguyn tc chung ca phng php hin vi in t

Chm tia in t c to ra t hai sng phng in t s c hi t ln mu nghin cu. Khi chm tia in t p vo mu s pht ra cc chm tia in t phn x v in t truyn qua. Chm tia in t truyn qua ny c i qua in th gia tc vo phn thu v bin i thnh mt tn hiu nh sng, tn hiu ny c khuch i, a vo mng li iu khin to ra sng trn mn nh. Mi im trn mu cho mt im tng ng trn mn nh, sng ti ph thuc vo lng in t pht ra ti b thu.

C ch phng i ca TEM l nh thu knh in t t bn trong h o. Thu knh ny c kh nng thay i tiu c. Khi tia in t c bc sng c 0,4nm chiu ln mu hiu in th khong 1 OOkV, nh thu c cho bit chi tit hnh thi hc ca mu theo tng phn tn x v tng phn nhiu x, qua c th xc nh c kch thc ht mt cch kh chnh xc.S dng chm tia in t to nh mu nghin cu, nh khi n mn hnh hunh quang c th t phng i theo yu cu. Chm tia in t' c to ra t catot qua hai t quang in t s c hi t ln mu nghin cu. Khi chm tia in t p vo mu s pht ra cc chm tia in t phn x v in t truyn qua. Cc in t phn x v in t truyn qua ny c i qua in th gia tc vo phn thu v bin i thnh mt tn hiu nh sng, tn hiu ny c khuch i, a vo mng li iu khin to ra sng trn mn. sng ti trn mn nh ph thuc vo lng in t pht ra ti b thu v ph thuc hnh dng b mt mu nghin cu.-38-

-39-

CHNG II: THC NGHIM2.1 Dng c, thit b v ho cht2.1.1 Dng c: Bnh cu hai c 500ml. Pipet 2ml, 5ml, lOml. Bnh nh mc 250ml, 500ml, lOOOml. ng ong lOOml. Bnh nh git iu chnh tc nh. Nhit k thu ngn 100c. Chn nung, cc cn, ng nghim.2.1.2 Thit b: Cn in t c chnh xc 10"4g. My khuy t gia nhit. B siu m tn s 46kHz, cng sut 200W. L nung c nhit nung ln nht 1000c. My ly tm. My o pH. B khuy c. T sy.2.1.3 Ho cht Axit photphoric H3PO4 85% (d = 1,69), loi PA (Trung Quc). Canxi hiroxit Ca(OH)2, loi PA (Trung Quc). cn 96.2.2 Nghin cu quy trnh tng hp bt HABt HA c tng hp t Ca(OH)2 v H3PO4 theo s b tr th nghim c trnh by trn hnh 2.1.

Quy trnh thc nghim c trnh by trn hnh 2.2. Cc th nghim c tin hnh qui m to ra khong 1 Og HA.M t th nghim: Ho tan Ca(OH)2 vo 200ml nc ct trong bnh cu 500ml thu c huyn ph c nng 0,5M. Mt bnh nh git cha 200ml H3PO4 0,3M c t trn bnh cu. Hn hp phn ng c khuy v gia nhit bng my khuy t n nhit cn nghin cu, duy tr ti nhit trong ton b thi gian phn ng. Nhit th nghim c o bng nhit k thu ngn vi sai s 2c. Nh dung dch axit H3PO4 vo bnh phn ng nhng tc xc nh. Sau khi nh ht axit, tip tc khuy hn hp thm 2 gi. Sn phm thu c dng huyn ph, mu trng. lng 24h ri thu sn phm bng cch ly tm vi tc 4400vng/pht. Ra sn phm 3 ln bng nc ct, ra ln cui bng axit H3PO4 10'3M. Ly sn phm ra mt knh ng h v sy 70c n kh, nghin mn ri sy tip 130c trong 24h.Mt s mu sau khi sy c nung 900c trong lgi xc nh s tn ti ca cht u Ca(OH)2 trong sn phm HA.H3PO4 H20

Hnh 2.2: S quy trnh thc nghim tng hp bt HAKhuy v gia nhit

2.3 Kho st nh hng ca nhit Cc th nghim c tin hnh cc nhit 0, 10, 30, 60 v 90c.Tc khuy:300 - 350vng/phtTc cp axit H3PO4:1,6ml/phtNng dung dch H3PO4:0,3MNng huyn ph Ca(OH)2:0,5MCc bc thc nghim c tin hnh theo quy trnh m t 2.2 Sn phm HA c nh gi bng cc phng php XRD, FTIR, SEM, TEM.2.4 Kho st nh hng ca tc cp axitTc cp axit H3P04ca cc th nghim c thc hin nh sau:Th nghim s 1:l,lml/phtCa(OH)2H20

Th nghim S2:l,6ml/pht-40-

-42-

-43-

Th nghimS3:2,2ml/phtTh nghimS4:7ml/phtTh nghimS5:Rt nhanh ton blng axit vo (tc rt ln).Cc th nghim c tin hnh nhit 30c. Cc thng s khc (tc khuy, nng , dung mi) c duy tr nh mc 2.3.Cht lng HA c nh gi bng XRD, FTIR, SEM.2.5 Kho st nh hng ca nng cht phn ngThc hin cc th nghim 30c vi ba mc nng nh sau:Th nghim c 1: H3PO4 0,09M v Ca(OH)2 0,15MTh nghim c2: H3PO4 0,3M v Ca(OH)2 0,5MTh nghim c3: H3PO4 0,9M v Ca(OH)2 1,5MCc thng s khc (tc khuy, tc cp axit, dung mi) c duy tr nh mc 2.3.S dng cc phng php XRD, FTIR, SEM nh gi sn phm th nghim.2.6 Kho st nh hng ca dung miCc th nghim c tin hnh 30c trong cc dung mi: nc, hn hp etanol + nc v etanol (96).Th nghim Di: Cc cht phn ng c pha trong ncTh nghim D2: Cc cht phn ng c pha trong hn hp etanol + nc, t l 1:1 v th tch.Th nghim D3: Cc cht phn ng c pha trong etanolCc thng s (nng , tc khuy, tc cp axit) c duy tr nh mc 2.3.Sn phm c nh gi qua XRD, FTIR, SEM.2.7 Kho st nh hng ca tc khuy trnTin hnh kho st tc khuy ba gi tr: Vi: 100 - 150vng/pht V2: 300 - 350vng/pht v3: 450 - 500vng/phtThc hin cc phn ng 30c, cc thng s (nng , tc cp axit, dung mi) c gi nguyn nh mc 2.3.Sn phm c nh gi bng XRD, FT1R, SEM.2.8 Kho st s b nh hng ca sng siu mBnh phn ng iu ch HA c t trong b siu m vi tn s 46kHz, cng sut 200W. Hn hp phn ng c khuy bng my khuy c. Nhit c duy tr 30c, cc thng s khc ging mc 2.3.Mu khng chiu sng siu m:P]Mu chiu sng siu m:p2Sn phm c o XRD, FTIR, SEM, TEM.2.9 Chun b mu phn tchTrc khi phn tch, sy mu HA 70c, nghin nh, sy tip 130c trong 24h kh hon ton, sau nghin mn. Cc mu c o bng cc phng php sau:a. Nhiu x tia X (XRD)Cc mu c o XRD trn my SIEMENS D5005 Bruker (c), ti Khoa Ho hc (Trng i hc Khoa hc T nhin - i hc Quc gia H Ni), cc iu kin nh sau: bc x Cu-Ka c bc sng =1.5406 A, cng dng in 30mA, in p 40kV, gc qut 20 = 10 -- 70, tc qut 0,030/giy.b. Ph hng ngoi (FTIR)Ph FTIR ca cc mu c ghi trn my IMPAC 410 - Nicolet (M), ti Vin Ho hc (Vin KH&CN Vit Nam). Cc mu c nn p thnh vin vi KBr theo t l (1:400), c o trong khong t 500 n 4000CIT1"1.c. Hin vi in t qut (SEM)nh SEM ca cc mu c o trn thit b hin vi in t qut Hitachi S4800 (Nht Bn), ti Vin Khoa hc Vt liu (Vin KH&CN Vit Nam). Trc khi o, cc mu c ph Pt trong chn khng tng nt ca nh SEM do HA c dn in km.d. Hin vi in t truyn qua (TEM)nh TEM ca cc mu c o trn thit b hin vi in t' truyn qua JEM - 101 (Nht Bn), ti Phng Hin vi in t (Vin V sinh Dch t Quc gia). Trc khi o, cho mt lng nh mu vo etanol, sau t trong b siu m khong 3 gi bt HA phn tn ng u.CHNG III KT QU V THO LUN3.1 Quy trnh tng hp HATrong lun vn ny, chng ti la chn phng php tng hp bt HA kch thc nano t canxi hiroxit v axit photphoric. Trong h Ca(OH)2 - H3PO4, qu trnh to thnh HA theo phn ng (1.6):1 OCa(OH)2 + 6H3PO4 = Ca]0(PO4)6(OH)2 + 18H20 Theo nhiu ti liu [16], [28], phn ng gm hai giai on: u tin l qu trnh ho tan v phn li Ca(OH)2 rn v H3PO4 thnh cc ion Ca2+, H+, OH', cc nhm photphat; sau n qu trnh kt hp ca cc ion Ca2+, PO43' v OH to thnh kt ta HA kch thc nanomet. Hai qu trnh ny xy ra rt nhanh v gn nh ng thi do G (bin thin nng lng t do Gibbs) ca phn ng (1.6) c gi tr rt m (~ -3030 Kcal/mol) [10] v tch s tan ca HA rt nh (1059) [17].u im ca phng php l c th khng ch cc thng s phn ng thng qua vic tm hiu v can thip vo qu trnh kt tinh thu c sn phm HA c cht lng mong mun. Bn cht ca phng php l i t cc tiu phn rt nh, dng ion trong dung dch to thnh cc sn phm kt ta c kch thc ln dn t kch thc nanomet ban u. Do vy, thay i cc iu kin ch to nh nhit , thi gian, pH, dung mi... c th kim sot c s ln ln, hnh dng v tinh th ca sn phm. Hn na, phn ng khng i hi phi thng xuyn iu chnh pH. y l phng php dng cc ho cht c bn, d kim. ng thi, quy trnh v thit b n gin, thch hp vi trin khai sn xut cng nghip, thn thin vi mi trng v ang c s dng ph bin trn th gii. Tuy nhin, iu kin to ra HA c tinh th cao l kh cht ch. Qu trnh kt ta ny c th to ra cc sn phm trung gian l nhng hp cht canxi photphat nh canxi photphat v nh hnh (ACP) c thnh phn thay i nh Ca3(P04)2-2x(HP04)3x.nH20, octacanxi photphat (OCP) Ca8(HP04)2(P04)4.5H20 v canxi hirophophat ihirat (DCPD) CaHP04.2H20 [14]. Tuy vy, cc sn phm trung gian ny khng bn, s tip tc chuyn ho thnh HA l dng bn hn trong thi gian gi ho sn phm.S dng cc phng php vt l gip kho st nh hng ca cc iu kin phn ng n cht lng sn phm HA nh n pha, tinh th, kch thc tinh th v hnh dng ht...3.2 Kho st nh hng ca nhit Cc th nghim kho st nh hng ca nhit trong qu trnh tng hp bt HA trn c s nh gi thnh phn pha, tnh ton tinh th v kch thc ht trung bnh ca sn phm.a. Thnh phn phaTrn gin XRD, vch nhiu x cng 100% ca Ca(OH)2 v tr 20 = 34 (JCPDS #4-0733), trng vi vch cng 24% ca HA (20 =34,5, JCPDS #24-0033). Do vy, c th khng nh trong sn phm HA to thnh c cn tn ti cht u Ca(OH)2 hay khng, trc khi o XRD, mu c nung n 900c. n nhit ny, Ca(OH)2 chuyn thnh CaO theo phn ng:Ca(OH)2 CaO + H20(3.1)Cc vch nhiu x mnh ca CaO (JCPDS #37-1497) u v tr tch bit so vi HA.Gin XRD ca tt c cc mu nung 900c c a ra trn hnh 3.5

Hnh 3.5: Gin XRD ca HA sau khi nung 900 trong 1 gi Trn gin ca tt c cc mu nung n 900BC ch xut hin cc vch nhiu x c trng cho HA, khng thy s c mt ca cc cht u hay cc cht khc nh cc mui canxi photphat. Nh vy, theo phng php XRD HA tng hp c l n pha.b. Kt qu phn tch XRD Gin XRD c ch ra hnh 3.1.

Hnh 3.1: Gin XRD ca bt HA cc nhit phn ng khc nhau Trn cc gin ch xut hin cc vch nhiu x c trung ca HA (JCPDS 009-0432), khng thy s c mt ca cc pha l, chng t sn phmHA n pha. Cc vch nhiu x gm mt vch c cng mnh nht 20 = 31,77 ca mt phng (211) v hai vch c cng ngang nhau 32,196 v 32,902 tng ng vi cc mt phng (112) v (300). Ngoi ra cn cc vch c cng tng i mnh cc v tr 25,86; 30,04; 39,793; 46,683; 49,458 [14].Hnh 3.1 cho thy, cc vch c trng dn tch bit khi nhau v c cng tng ln, ng thi rng ca cc vch c trng gim. iu chng t nhit nh hng mnh n vic hnh thnh cu trc tinh th ca HA.T gin XRD, p dng cc cng thc (1.19) v (1.20), xc nh c kch thc tinh th trung bnh v tinh th ca HA. Ket qu c a ra trong bng 4.Bng 4: Anh hng ca nhit n kch thc tinh th trung bnh v tnh th ca bt HASTTNhit (C)D(nm) theo ScherrerTc tng kch thc(%) tinh th(%)Tc tng tinh th(%)

Ti020,3825

T21021,354,725,933,7

T33026,9232,147,3789,5

T4603571,774,71198,8

T59036,981,184,44237,8

Cc kt qu trong bng 4 cho thy, sn phm bt HA c kch thc kh nh, khi tng nhit phn ng kch thc tinh th trung bnh tng ln. Nhit tng, tc phn ng v tc to mm tng ln dn n s mm tinh th cng tng. Mt khc, khi nhit tng lm cho tc pht trin tinh th tng ln. Tuy nhin, tinh th tng rt nhiu so vi kch thc tinh th (Bng 4) nn nhit tng nh hng n tc pht trin tinh th nhiu hn. V th nh hng tng cng ca nhit l lm tng kch thc tinh th trung bnh.T cc kt qu v tinh the cho thy, tinh th tng khi tng nhit phn ng nht l vng nhit cao. 0 v 10c, tinh th ca HA tng i thp (ln lt l 25% v 25,93%). tinh th tng mnh (t 74,71% v 84,44%) khi nhit phn ng tng n 60c v 90c, tng ng vi tc pht trin tinh th hai nhit ny l 198,8% v 237,8% so vi tinh th 0c. iu ny cho thy tinh th HA pht trin thun li nhit cao.So vi gin XRD ca mu HA khng nung, trn gin ca cc mu HA nung n 900c, cc vch nhiu x tr nn hp hn, mt s vch (20 = 32,19; 32,87; 34,05,...) c cng mnh hn.Nh vy, tinh th HA pht trin thun li khi tng nhit phn ng v qu trnh tinh th ho tip tc xy ra khi nung mu n nhit cao.c. Anh SEM v TEMnh SEM ca mu HA tng hp nhit khc nhau c the hin trn hnh 3.2.

nh TEM ca cc mu tng hp cc nhit khc nhau c trnh by trn hnh 3.3.

-64-

-63-

HA 1 0C.0 0 8Print Mag: 80400x 9 51mm/K\100 nm4:20:42 p 07/08/09v^/HV=80.0kV4:46:58 p 07/06/09HV-8 0.0kVTIM Mode : ImayingDiroct May:KML.ab-N.lHK

TEM Mode: ImngngDrect Mag :4 0 00 0EMLab-NIHE

HA.-3 0C.0 0 8Print Mag : 60400X @ 51 b :3V :3> p OV/OS/O?TEM Modc: Iraagng100 rirn HV = 80.UkV Dircct Mag: 40000X T-MT.flb-NTNRHA-6 0C.0 0 9Print Mag: 8040X p 51 5 '.24 :54 p 07/08/09 TIiM Mode: imaging(d)100 nm HV =60.0 k V Direct Mag: 4000X EMLab-NIHE

Hnh 3.3: Anh TEM ca cc mu bt HA c tng hp cc nhit khc nhau:HA-9 0C.D09Print Mag : 8040Ox (r bl 5 -.03 :21 p 07/06/09 TEM Mode:Imaging10 0 nmHV -80.0 kVDirect Mag : 40000xFWT.fih-NTHH

(b) - 10c(a) - 0c

(c) - 30c(d) - 60c(e) - 90c

Quan st nh SEM v TEM cho thy nhit tng hp khng ch nh hng n kch thc ht trung bnh m cn nh hng n hnh dng ca sn phm HA. Khi tng nhit tng hp, kch thc ht HA tng mnh.Mu tng hp 0C: Tinh th ch yu dng hnh que, kch thc rt nh, mt s tinh the kt tp vi nhau thnh tng m. ng knh ca ht khong 10 n 14nm, di khong 30 n 40nm.Mu tng hp 10C: Cc ht c hnh dng tng t nh mu tng hp 0c nhng c kch thc ln hn. ng knh ca ht khong 20 n 22nm, di nht khong 50nm.Mu tng hp 30C: Tinh th c dng hnh que, ng knh ln nht khong 14 n 20nm, di khong 51 n 72nm.

Mu tng hp 60C: Tinh th hnh que tip tc pht trin, ng knh ht ln nht khong 25 n 30nm, chiu di c 54 n 73nm.Mu tng hp 90C: Tinh th hnh que pht trin hn, ng knh khong 26 n 40nm, chiu di 75 n 82nm.Kch thc ht trung bnh tnh theo cng thc Scherrer (Bng 4) c sai lch so vi kch thc ht quan st c trn nh SEM v TEM. iu ny c th l gii l do s khc nhau nhiu v hnh dng ht thc t (hnh que) v hnh dng ht gi thit (hnh cu) p dng cng thc Scherrer. Thc t cho thy kch thc ht HA c ng u khng cao (c bit nhit thp), do vy cc phng php xc nh kch thc ht nu trn ch mang tnh so snh tng i vi nhau.Vt liu kch thc nano c nng lng b mt rt ln nn chng c xu hng kt tp cc ht vi nhau to thnh nhng ht ln hn thun li hn v mt nng lng. c bit i vi HA, do c cha cc gc P043' c xu hng polime ho v cc gc OH d to lin kt hiro vi nhau. iu ny th hin trn nh SEM, cc ht HA kt tp vi nhau thnh tng m, c bit l nhit thp. Khi tng nhit kch thc ca cc m gim dn, tuy nhin kch thc cc ht to m li tng dn.d. Kt qu o FTIRPh FTIR ca sn phm HA tng hp cc nhit khc nhau c trnh by trn hnh 3.4.

Wavemimbers (cm-1)

Hnh 3.4: Pho FTIR ca cc HA c tong hp 5 nhit Trn c 5 mu u xut hin cc di ph c trung cho cu trc HA. Cc di ph cc v tr khong 630 v 3570cm'1 c trng cho cc dao ng ca nhm OH' trong cu trc. Cc di ph v tr t 1100 n 900, 601 v 574cm 1 c trng cho cc dao ng ca nhm PO43'. Cng cc di ph 631, 601 v 574cm1 c xem l ch th cho tinh th ca sn phm [14]. Khitng nhit , cng ca cc di ph c trung tng ln chng t tinh th pht trin tt hn.Trn gin XRD khng thy xut hin cc pic c trung ca CaC3, CaHP4 hay Ca3(P04)2 c th do lng cht qu t. Tuy nhin, khi phn tch ph FTIR ca cc mu HA (hnh 3.4) thy xut hin cc di ph c cng tng i yu nm vng 1410 v 1550cm_1. Cc di ph ny c gn cho nhm CO32" trong cu trc (khi n thay th nhm OH" hoc P043"). Cng ca cc di ny gim dn khi tng nhit phn ng, v nhit cao tinh th pht trin hon thin hn. S c mt ca CO32' l do s hp th C02 trong qu trnh phn ng, lc ra, bo qun v l thnh phn lun i km trong nguyn liu.3.3 Kho st nh hng ca tc cp axitH3PO4 l mt axit c mnh trung bnh, phn ly theo 3 giai on [33]:(3.2)(3.3)(3.4)

H3P04 HH2P04 + H+pKai = 2,2H2P04 HPC>4 +H+pKa2 = 7,2HPO;- nP03/ + H+pKa3=12,3V vy nu thm axit vi tc cao, pH ca dung dch s gim t ngt, dn n s phn ly axit khng hon ton, to ra cc ion HPO42 v H2PO4. Khi sn phm ca phn ng l cc canxi photphat c thnh phn thay i Ca10-x(HPO4)x(PO4)6-x(OH)2.x (Calcium - Deficient HA, CDHA), chng hn nh: Ca9(HP04)(P04)50H hoc Ca8(HP04)2(P04)4.5H20...S thay i pH theo thi gian ca cc phn ng khi tc cp axit thay i c th hin trn cc biu trong hnh 3.6.

(a)(b)Hnh 3.6: S thay i pH khi cp axit theo cc tc khc nhau.Si = 1,1 ml/pht; s2 = 1,6 ml/pht; s3 = 2,2 ml/pht; s4 = 7 m/pht;s5: tc rt nhanh (lng axit cho vo cng mt thi im)Gi tk l thi im nh ht axit vo bnh phn ng. cc th nghim t Si n s4, trong thi gian cp axit, pH ca hn hp phn ng gim rt chm. en gn thi im tk, pH gim xung nhanh chng, t khong 12 v 8 - 9. pH thi im tk ca cc th nghim t Si n s4 u ln hn 8.Quan st hnh 3.6b cho thy, pH ca hn hp phn ng ti thi im tk gim t ngt t 13 xung khong 5. Tuy nhin, sau khong 25 pht tip theo pH ca hn hp phn ng li tng ln trn 10 v duy tr trong khong 90 pht. a. Kt qu XRDHnh 3.7 l gin nhiu x tia X ca bt HA c tng hp 5 tc cp axit khc nhau.0$0lOOHI gwn (pht)OISO50Thi g)n (pb)100I

(a;

2-Theta ScaleQllt NLM tCJ>e:tt030--3*|-'k'.2S*C*X'' i)tx>crEiiF 1)TI-c*w30I-:I.-WI 15ICa-> j>ea)-ceaeo:-*^0J-I tbsoooo- sms 120X0-1

Hnh 3.7: Gin XRD ca bt HA a: cc phn ng s, s2, S, s4 b: phn ng s52-Theta Scale

c: phn ng s5 khi nung mu 600c trong gi Quan st hnh 3.7a cho thy, trn cc gin ch xut hin cc vch nhiu x c trung ca HA, khng thy s c mt ca cc pha l. Cng v rng ca cc vch c trng khc nhau khng r rng chng t tc cp axit t Si n s4 nh hng khng mnh n tinh th v kch thc tinh th trung bnh ca HA. Gin XRD (hnh 3.7b) ca mu c tng hp th nghim s5 (tc cp axit ln nht) cho thy, sn phm l n pha nhng cc pic c trng ca HA b chng chp to thnh mt pic rng v c cng yu. iu ny chng t sn phm thu c c tinh th km nht, ch yu tn ti dng v nh hnh.Kch thc tinh th trung bnh, tinh th ca sn phm HA c tnh ton theo cc cng thc (1.19), (1.20) v c a ra trong bng 5.Bng 5: Anh hng ca tc cp axit H3PO4 n kch thc trung bnh v tinh th trong bt HASTTTc cp H3PO4 (ml/pht)D(nm) theo Scherrer tinh th(%)

ChanungNung600c

Si1,124,863662,94

s21,626,9247,3777,81

s32,224,7838,4651,18

s4724,2728,956

s5Tc rt nhanh18,16Khng xc nh c2,4

Ket qu trong bng 5 cho thy, tc cp axit khng nh hng nhiu n kch thc tinh th trung bnh nhng nh hng n tinh th ca sn phm. Kch thc ht nm trong khong 24 - 25nm, ring th nghim s2 cho kch thc ht ln nht (27nm) v th nghim S5 cho ht c kch thc nh nht (18nm).Khi tng tc cp axit t Si n s2 tinh th tng t 36% n 47%. Tip tc tng tc cp axit th tinh th li gim t' 47% (S2) xung cn 28,9% (S4). Th nghim s5 (tc cp axit rt nhanh) khng th xc nh c tinh th do cc vch nhiu x c trng ( v tr 20 = 32,196 v 32,902) dng tnh tinh th khng tch bit nhau.So snh cc hnh 3.7b v 3.7c cho thy, trn gin XRD ca mu sau khi nung, cc pic chng chp bt u tch bit. Theo kt qu bng 5, khi nung sn phm 600c trong mt gi, tinh th tng ln mnh. iu ny cng ph hp vi quy lut chung i vi cc vt liu c cu trc tinh th l qu trnh tinh th ho tip tc xy ra khi nung mu nhit cao.Tc cp axit thay i s nh hng n kch thc v tinh th ca sn phm. Tc cp axit tng ln lm cho tc phn ng chung tng ln, iu ny thun li cho s to mm v hnh thnh cc ht c kch thc nh.Tuy nhin, nu tc cp axit qu ln, phn ng trung ho gia Ca(OH)2 v H3PO4 xy ra chm hn s dn n hin tng qu axit cc b. iu ny nh hng khng tt n tinh th, c bit l n pha ca sn phm. V khi cp axit vi tc ln, pH ca hn hp gim t ngt xung 5 - 6, to iu kin cho cc mui canxi photphat khc to thnh.Tc cp axit chm s m bo thi gian phn ng to thnh HA xy ra theo hai giai on (giai on ho tan Ca(OH)2 v giai on kt ta HA), to ra hn hp phn ng ng nht, sn phm HA thu c l n pha v c tinh th cao. Nhng tc cp axit qu chm s to thnh lp sn phm mn, bao bc ht Ca(OH)2 ngn chn s tip xc vi axit, lm gim tc chung v ko di khng cn thit thi gian phn ng.b. Kt qu nh SEMV tc cp axit nh hng khng nhiu n kch thc ht trung bnh ca HA nn y ch a ra i din ba nh SEM ca ba th nghim.

Hnh 3.8: Anh SEM ca bt HA tng hp ba tc cp axit H3P04S: ,lml/pht s4: 7ml/pht S5: tc rt lnQuan st nh SEM nhn thy, sn phm th nghim Si v S4 ch yu tn ti dng hnh que. Cc ht c ng knh 20 - 30nm, di 60 - 70nm, bin gia cc ht r nt. Mt s ht c hin tng kt t to thnh cc m c kch thc khong 100 - 150nm.Trn nh SEM ca mu S5 (tc cp axit rt ln) khng quan st c cc ht ring r. Sn phm tn ti thnh tng khi ln c kch thc khc nhau. Ph hp vi kt qu tnh ton trong bng 5, tinh th ca mu rt thp, gn nh khng xc nh c, sn phm ch yu tn ti dng v nh hnh.c. Kt qu FTIR

Wavanumbere (cm-1)Hnh 3.9: Ph FTIR ca bt HA cc toc cap axit Trn ph FTIR ca cc mu HA t Si n s4, cc di c trnng cho tinh th HA u xut hin. c trng cho cc dao dng ca nhm PO43' l cc di

ph v tr 1100 - 900, 601 v 574cm"1. Hai di ph 630 v 3570cm'1 c trng cho cc dao ng ca nhm ' trong cu trc.Nh trnh by trn, HA c cu trc tinh th tt phi tn ti cc di c trung cho cc nhm PO43 v . mu S5, khng xut hin di ph v tr 631cm"1 l mt trong hai di c trng cho nhm " ca HA. iu ny chng t HA thu c phn ng s5 c cu trc tinh th cha hon thin v tinh th thp.Qua cc phn tch gin XRD, nh SEM, ph FTIR c th kt lun, tu thuc vo mc ch s dng bt HA la chn tc cp axit ph hp trong khong t Si (1,1 ml/pht) n s4 (7ml/pht). V cc tc ny u cho sn phm HA n pha, c kch thc tinh th, hnh dng v tinh th tng ng nhau.Tc cp axit bng l,6ml/pht c la chn trong cc th nghim tip theo kho st cc yu t nh hng n cht lng sn phm HA.3.4 Kho st nh hng ca nng cht phn ngPhn ny kho st nh hng ca nng cht phn ng n n pha, kch thc ht trung bnh v tinh th ca sn phm.a. Ket qu phn tch XRD

Hnh 3.10: Gin XRD ca HA tong hp cc nng : , 2 v Quan st hnh 3.10 cho thy, gin XRD ca tt c cc mu u ging nhau v tng t nh mu chun (JCPDS 009-0432) v ca NIST. Trn cc gin ch xut hin cc vch nhiu x c trang ca HA chng t sn phm thu c l n pha. Cc vch c trng tch bit nhau kh r nt. rng v cng cc pic c trng 3 gin gn nh bng nhau, c ngha l kch thc tinh th trung bnh v tinh th ca sn phm thu c cc nng chnh lch nhau khng nhiu. Tuy nhin, cc pic gin 2 c cng mnh nht, iu chng t sn phm HA thu c c tinh th cao nht. Da vo cng thc Scherrer (cng thc 1.19), phng php phn gii pic (cng thc 1.20) v gin XRD (hnh 3.10), tnh c kch thc tinh th trung bnh, tinh the ca sn phm. Cc kt qu tnh ton c the hin trong bng 6.Bng 6: Anh hng ca nng cc cht phn ng n kch thc tinh th trung bnh v tinh th ca HATh nghimD (nm) theo Scherrer tinh th(%)

c,26,6431,43

c226,9247,37

c33143,18

Cc kt qu trong bng 6 cho thy, kch thc tinh th trung bnh tng nh theo nng cht phn ng. th nghim Cl (nng cc cht phn ng nh nht) kch thc ht trung bnh bng 26,6nm v tng ln 31nm th nghim (nng cc cht phn ng ln nht). iu ny c th gii thch nh sau: khi nng cht phn ng tng th tc to mm tinh th tng, nhng kh nng kt t ca cc mm tinh th to thnh tinh th ln hn cng tng. V cng tc khuy trn nn khi s mm tinh th tng ln lm cho nht ca dung dch tng. iu ny dn n cng khuy thc trong dung dch s gim, to iu kin cc mm tinh th mi sinh kt t vi nhau. Do , kch thc ht trung bnh tng khi nng cht phn ng tng.Theo cc kt qu bng 6, tinh th khng tng theo quy lut. tinh th tng t 31,43% th nghim Cl n 47,37% th nghim c2. Khi tip tc tng nng cht phn ng th tinh th li gim xung 43,18% th nghim c3. C th gii thch nh sau: khi nng cht phn ng tng, tc to mm v tc pht trin tinh th u tng. Nhng nu nng cht phn ng qu ln dn n qu bo ho qu cao, lm cho tc to mm chm hn tc pht trin tinh th. Bi v, khi qu bo ho qu cao, nng ion rt ln s cn tr s chuyn ng ca cc phn t' v ion, lm gim tc to mm v tng tc pht trin tinh the. Yeu t ny lm cho tinh th khng tng tuyn tnh khi tng nng cht phn ng.b. Kt qu nh SEM

T nh SEM c th nhn thy, cc ht ch yu tn ti dng hnh que.Mu tng hp th nghim c 1: Kch thc cc ht khng u nhau, cc bin ht khng r nt. ng knh khong 10 - 25nm, di 25 - 40nm.Mu tng hp th nghim c2: Kch thc cc ht kh ng u, bin gia cc ht r nt. ng knh khong 15 - 20nm, di 35 - 45nm.Mu tng hp th nghim c3: Tinh th hnh que pht trin ln hn, cc ht kt t nhiu. ng knh khong 20 - 35nm, di 40 - 70nm.Nh vy, nng cht phn ng trong kho st ny khng nh hng n hnh dng ht.c. Kt qu FTIRHnh 3.12 trnh by ph hng ngoi ca sn phm bt HA thu c cc th nghim C], c2 v c3.

Hnh 3.12: Ph FTIR ca bt HA thu c cc th nghim vi nng cht phn ng khc nhauTrn cc ph FTR ca HA ba th nghim Cl, 2 v C3, u xut hin cc di ph c trang ca cc nhm cu trc trong phn t HA. Cc di ph vng 1100, 1044, 965, 574 v 471 cm'1 c trang cho cc dao ng ca nhm PO43' v vng 3570, 631 cm'1 c trng cho cc dao ng ca nhm '. c2 v C3 cn xut hin cc di hp th yu, c trng cho nhm HPO42' vng 875 cm'1 v di c trng cho nhm C032 vng 1450 cm'1 v 1410 cm' . Tuy nhin trn gin XRD khng quan st c pha , iu ny chng t s c mt ca ion CO32 trong mu khng ng k.Da trn cc kt qu phn tch c th kt lun, ba mc nng kho st khng nh hng n n pha v hnh dng tinh th nhng nh hng nh n kch thc tinh th v tinh th ca sn phm.3.5 Kho st nh hng ca dung miGi tr pH ca cc cht phn ng trong cc dung mi khc nhau c xc nh bng thc nghim.Bng 7: Gi tr pH ca cc dung dch cht phn ng khi pha trong cc dung miDung miNc(Di)Hn hp etanol + nc(D2)Etanol(D3)

pH ca huyn ph Ca(OH)212,921211,5

pH ca dung dch H3PO41,732,122,4

Nh vy, gi tr pH ca huyn ph Ca(OH)2 t' 12,92 trong dung mi Di gim xung cn 11,5 trong dung mi D3. Ngc li, gi tr pH ca dung dch H3PO4 t 1,73 trong dung mi Di tng ln 2,4 trong dung mi D3.Sn phm c phn tch bng gin XRD v ph IR nh gi n pha, kch thc ht v tinh th.a. Ke qu phn tch XRDHnh 3.13: Gin XRD ca bt HA tong hp dung mi

Trn cc gin XRD ca mu Di v D2 ch xut hin cc vch nhiu x c trng ca HA, khng thy s c mt ca pha l. Chng t sn phm HA thu c hai th nghim ny l n pha. Cc vch c trung tch bit nhau r nt v c cng mnh th hin tinh th tt. rng ca cc vch c trng tng i ln cho thy kch thc ht kh nh. p dng cng thc (1.19) v da vo gin Di, D2 tnh c kch thc trung bnh ca sn phm HA ln lt l 26,9nm v 32,6nm. Nh vy, dung mi hn hp khng nh hng n n pha ca sn phm. C th gii thch nh sau: lng nc trong dung mi hn hp (D2) phn ng to HA xy ra nh trong dung mi nc (Di). Tuy nhin, kch thc ht trung bnh tng ln trong dung mi D2. Nguyn nhn l do phn t etanol km phn cc hn nc, hu nh khng tham gia vo qu trnh phn ly ca Ca(OH)2 v qu trnh kt ta to HA. V vy, nng ion Ca2+ gim, qu bo ho gim dn n tc to mm cng gim to iu kin kch thc tinh th tng.Gin D3 cho thy, sn phm thu c khng n pha v ngoi cc vch c trng ca HA, trn gin cn xut hin cc vch c trng ca CaHP04 cc v tr 20 = 26,8; 30,4; 32,5 v 35,9 (JCPDS 003-0423) vi cng kh mnh. Cc pic c trung ca HA b chng chp v cng yu, chng t tinh the km.p dng cng thc (1.20) v da vo cc gin XRD trn hnh 3.13 tnh c tinh th ca HA tng hp trong cc dung mi nh sau:Bang 8: Anh hng ca dung mi n tinh th ca HASTTDung mi tinh th (%)

DiNc47,37

d2Etanol + nc48,78

D3Etanol14,63

-66-

-#-

s liu trong bng 8 cho thy, tinh th th nghim Di v D2 tng ng nhau ( 47 - 48%), cn D3 rt thp (14,63%). Etanol l dung mi km phn cc hn nc rt nhiu, do lm hn ch qu trnh ho tan v phn ly ca cc cht phn ng thnh cc ion. Tuy nhin, v AG ca phn ng (1.6) c gi tr rt m nn vn thu c HA nhng s hnh thnh cu trc tinh th ca chng khng thun li do vy D3 tinh th gim mnh.Bn cht ca H3PO4 l mt axit trung bnh, v th trong dung mi etanol s phn ly nc th 3 theo phng trnh (3.4) kh khn hn. Cn bng (3.4) chuyn dch sang tri, nng ion HPO42 tng ln. Do vy, cn c phn ng kt hp ca cc ion Ca2+ v HPO42" to thnh CaHP04 theo phng trnh sau:Ca2+ + HPO42' - CaHP04(3.5)Khi , sn phm thu c trong th nghim D3 ngoi HA cn c thm mui CaHP04.b. Ket qu chp SEMCD2)20nnri Es x200k SE(M) 5/27/2009Hnh 3.14: Anh SEM ca bt HA c tong hp t cc dung mi: D: ncD2: hn hp nc + etano D3: etanol

Mu c tng hp D1: Tinh th ch yu tn ti dng hnh que, bin ht r nt. Kch thc ht kh nh, ng knh khong 20 - 30nm, di 30 - 45nm.Mu c tng hp D2: Tinh th vn tn ti dng hnh que, bin gia cc ht th hin r nt hn. Kch thc ht cng ln hn, ng knh 20 - 35nm, di 40 - 60nm.Mu c tng hp D3: Tinh th rt ln, khng c hnh dng xc nh. Khng phn bit c tinh th HA v tinh th CaHP04.Qua nh SEM cng c th nh gi nh tnh l tinh th ca mu Di v D2 cao hn mu D3.c. Kt qu phn tch FTIRHnh 3.15 l ph FTIR ca bt HA c tng hp trong cc dung mi khc nhau.Wavenun)bers(cm-1)

Hnh 3.15: Ph FTIR ca bt HA c tng hp trong cc dung mi khc nhau

Trn ph FTIR ca Di v D2 u xut hin cc di hp th c trng cho nhm PO43 v OH' trong cu trc HA, cc di hp th yu ca nc t do 3453 cm'1 v 1627 cm"1, ngoi ra cn di hp th rt yu ca nhm HPO42' 873 cm1. mu D3 khng xut hin y cc di ph c trung cho nhm PO43' v " trong cu trc ca HA. i vi nhm PO43' khng c di ph 1100 v 965 cm'1, i vi nhm OH' khng xut hin di ph 631 cm"1. Chng t cu trc tinh th ca HA trong D3 cha pht trin hon thin. Bn cnh , cc di hp th mnh xut hin 875 cm'1 v 1415 cm'1 c quy kt cho nhm HPO42 trong CaHP04 v mt lng nh trong phn t' HA. Vic thay th ny s lm gim t l Ca/P ca bt HA, dn ti to thnh sn phm HA khng ng t l hp thc.Nh vy, trong cc dung mi khc nhau in ly ca Ca(OH)2 v H3PO4 s khc nhau dn n pH ca hn hp phn ng thay i. Yeu t ny nh hng mnh n n pha v tinh th sn phm. C th khng nh, etanol khng phi l dung mi thch hp cho qu trnh tng hp HA.3.6 Kho st nh hng ca tc khuy trna. Kt qu phn tch XRDGin XRD ca bt HA tng hp cc tc khuy trn khc nhau c th hin trn hnh 3.16.

2-Thet - Seele2-Thete-Seele

Hnh 3.16: Gin XRD ca bt HA tng hp cc tc khuy trnTrn cc gin XRD ch xut hin cc vch nhiu x c trng ca HA, khng thy s c mt ca pha l. Nh vy, tc khuy trn khng nh hng n n pha ca sn phm.Cc gin cn cho thy, nhng vch c trng ny dn tch bit v c cng tng ln, chng t tinh th tng khi tng tc khuy. rng ca cc vch c trung tng, c ngha l kch thc ht trung bnh gim i khi tng tc khuy trn. p dng cng thc Scherrer (cng thc 1.19) tnh ton kch thc tinh the trung bnh v p dng cng thc (1.20) tnh c tinh th ca sn phm. Cc kt qu c thng k trong bng 9.Bng 9: Anh hng ca tc khuy trn n kch thc tinh th trung bnh v tinh th ca bt HASTTTc khuy trn(vng/pht)D(nm) theo Scherrer tinh th(%)

V,100-15039,332,43

v2300-35026,9247,37

v3450 - 50022,3265,23

Cc s liu trong bng 9 cho thy, tc khuy trn nh hng mnh n tinh th. th nghim Vj, tinh th tng i thp (32,43%), gi trny tng ln 65,23% th nghim v3. C th gii thch nh sau, khi tng tc khuy trn, cc phn t Ca(OH)2 v H3PO4 phn ly nhanh chng thnh cc ion ng thi to iu kin thun li cc ion ny tip xc vi nhau. Yeu t ny c l thc y s kt tinh cc ion hnh thnh HA c cu trc tinh th tt hn, do vy tinh th ca sn phm tng ln.b. Kt qu chp SEM

Quan st nh SEM (hnh 3.17) cho thy, tc khuy trn nh hng n hnh dng v kch thc ht. Khi tng tc khuy trn, kch thc ht trung bnh gim. iu ny ph hp vi kt qu tnh ton kch thc ht trung bnh c a ra trong bng 9.Mu c tng hp V: Cc ht ch yu tn ti dng hnh que, c hin tng kt t gia cc ht to thnh cc m c kch thc ln, di 100 n 200nm. Cc bin ht khng r nt.

Mu c tng hp V2: Cc ht tn ti dng hnh que v bin ht r nt hn V. Tuy vn c hin tng kt t nhng t hn v kch thc cc m gim. ng knh cc ht khong 20 n 30nm, di 30 n 50nm.Mu c tng hp V3: Cc ht vn tn ti dng hnh que nhng di gim ng k, nhiu ht c dng gn hnh cu. ng knh khong 10 - 20nm, di khong 20 - 30nm. Bin ht r nt v cc ht kh u nhau.Nh vy, vi tc khuy ln hn thu c sn phm c kch thc ng u v cho cc bin ht r nt hn.S nh hng ca tc khuy trn n kch thc ht trung bnh c th gii thch nh sau: khuy trn l mt trong nhng cch hiu qu to ra h ng nht v cc yu t nh nng cht phn ng, nhit , pH, gip cc cht phn ng khuch tn tt hn v tip xc vi nhau nhiu hn, trnh hin tng phn ng cc b. Trong qu trnh phn ng, khuy trn cn c tc dng lm tng tc phn ng v nh hng n trng thi tp hp ca sn phm, c bit trong phn ng d th. Tc phn ng tng lm cho s mm tinh th hnh thnh trong mt n v thi gian tng ln, tng ng vi vic kch thc mi tinh th gim xung.4000350030002500200015001000

c. Kt qu phn tch FTIRHnh 3.18: Ph FTIRca bt HA tong hp cc tc khuy

Quan st hnh 3.18 cho thy c ba ph u xut hin cc di ph c trng cho nhm PO43 v OH' trong cu trc phn t HA. Tuy nhin, di ph vng Slcm'1 (c trung cho nhm OH trong cu trc ca HA) c cng tng dn khi tng tc khuy trn. Nguyn nhn l do tinh th tng khi tng tc khuy trn nh cc tnh ton trnh by trong bng 9. Quan st cc ph trn hnh 3.18 cn cho thy, vng ph 1638 - MOOcm'1 c trng cho nhm C32 c cng tng nh khi tng tc khuy t Vi n v3.Mu tng hp Vi v v2: xut hin di ph ca nhm HP042 vng 875C1T1'1 nhng cng ca di ph ny yu i nhiu V3. Chng t sn phm v3 cha lng HPO42' t hn.Tuy nhin, trong gin XRD c 3 mu khng quan st thy vch nhiu x ca hp cht cha nhm C032 v nhm HP042 do c th coi lng cht cha cc ion ny trong sn phm ch chim mt t l rt nh.Nh vy, vi ba mc tc khuy trn kho st cho thy, tc khuy trn khng nh hng n n pha v hnh dng tinh th, nhng c nh hng n kch thc ht trung bnh v tinh th ca sn phm.3.7 Kho st nh hng ca sng siu mCc nghin cu cho thy, bc x ca sng siu m cung cp nng lng cho phn ng, kch thch kh nng phn ng ca cc cht. Ket qu l tc ca phn ng tng ln, c bit i vi phn ng d th gia cc cht rn v lng. Siu m cn c tc dng tng s khuch tn ca cc ion trong dung dch n b mt mm tinh th, y nhanh qu trnh pht trin tinh th. Trong lun vn ny, chng ti mi ch bc u kho st nh hng ca sng siu m n hnh dng, kch thc trung bnh v tinh th bt HA so snh vi sn phm bt HA c iu ch trong iu kin ch khuy trn bng my khuy

a. Kt qu phn tch XRD1 1jbjlibuii.*4/

2-Theta - Scale(a)(b)Hnh 3.19: Gin XRD ca bt HA c tong hp trong iu kin khng chiu (a) v c chiu (b) bc x siu mTrn cc gin XRD ca hnh 3.19 ch xut hin cc vch nhiu x c trung cho tinh th HA, khng xut hin cc pha l.T cc gin nhn thy, cc vch c trng tch bit nhau, cng v rng ca cc vch c trng thay i khng nhiu nn ch quan st gin XRD cha th xc nh c s thay i v kch thc ht trung bnh v tinh th. S dng cng thc Scherrer (cng thc 1.19) v cng thc (1.20) tnh c kch thc tinh th trung bnh v tinh th ca HA. Cc kt qu tnh ton c th hin trong bng 10.Bng 10: Anh hng ca sng siu m n kch thc tinh th trung bnh v tinh th HASTTD(nm) theo Scherrer tinh th(%)

Pl26,9247,37

p227,046,54

Cc s liu trong bng 10 cho thy kch thc tinh th trung bnh tnh ton theo cng thc Scherrer ca sn phm thu c th nghim Pi v P2 xp x bng nhau. tinh th gim khng ng k, t 47,37% ( Pi) xung 46,54% ( p2).b. Ke qu chp nh TEMHA TN9.008Print Mag : 104000X p 51 ram 10:21:51 a 08/19/09(b)TEM Mode:Imaging100 nmHV=80.0kVDirect Mag: 50000X

H-30C-008PrintMag: 80400x@ 51 mm100 nm5:37:35 p 07/08/09HV=80.0kVTEM Mode: Imaging*Direct Mag: 40000xEMLab-NIHE

Hnh 3.20: Anh TEM ca bt HA c tng hp trong iu kin khng chiu(a) v chiu (b) bc x siu m nh TEM cho thy, di tc dng ca sng siu m, kch thc ht tng ln, chiu di ca ht c th ln n 164nm, ng knh khong 20 - 50nm. Trong trng hp khng c sng siu m, chiu di ca ht khong 30 - 72nm, ng knh 14 - 30nm. C th l gii nh sau, di tc dng ca sng siu m, qu trnh khuch tn ca cc ion n b mt v kt tinh trn cc mm HA xy ra nhanh hn, lm cho kch thc tinh th tng ln.Nh vy, sng siu m vi cng sut 200W v tn s 46kHz c s dng trong kho st ny khng nh hng n n pha v tinh th nhng c nh hng n kch thc ht ca sn phm HA.

KT LUN1. nghin tng hp c bt HA c kch thc nano t Ca(OH)2 v H3PO4. S dng cc phng php vt l nh XRD, SEM, TEM, FTIR xc nh cht lng sn phm trn c s nh gi n pha, kch thc tinh th trung bnh, hnh dng v tinh th ca sn phm.2. kho st nh hng ca cc yu t: nhit , nng cht phn ng, tc cp axit, dung mi, tc khuy trn v bc x siu m n n pha, kch thc ht trung bnh v tinh th ca sn phm HA. et qu cho thy, kch thc ht trung bnh v tinh the ca HA tng mnh khi tng nhit phn ng.Dung mi nh hng mnh n n pha ca sn phm. Trong dung mi etanol, sn phm ca phn ng gm HA v Tc cp axit khng nh hng n n pha nhng nh hng mnh n tinh th ca sn phm.Cc yu t cn li (nng cht phn ng, tc khuy, sng siu m) nh hng khng nhiu n n pha, kch thc ht trung bnh v tinh th ca sn phm.3. Cc sn phm bt HA thu c u c cc c trung v n pha, kch thc tinh th, hnh dng v tinh th. Trn c s cc kt qu t c, c th la chn iu kin tng hp bt HA ph hp cho nhng ng dng khc nhau trong tng iu kin c th.TI LIU THAM KHOTing Vit1. 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Li cm onVi lng knh trng v bit n su sc em xin chn thnh cm n Tin s o Quc Hng tn tnh hng dn em trong sut qu trnh lm lun vn.Em xin chn thnh cm n Gio s, Tin s V ng , Tin s Phan Th Ngc Bch c nhng kin qu bu gip em hon thnh lun vn ny.Ti xin chn thnh cm n cc c, cc ch, cc anh ch v cc bn cng tc ti Phng Ho V c - Vin Ho hc - Vin Khoa hc v Cng ngh Vit Nam to iu kin v gip ti rt nhiu ti thc hin tt cng vic ca mnh.Cui cng ti xin cm n gia nh v bn b gip , ng vin v to iu kin ti c th hon thnh tt lun vn ny.H ni, thng 12/2009 Hc vinV Thi Diu T VN 1CHNG I: TNG QUAN31.1. Tnh cht ca hyroxyapatit31.1.1. Tnh cht vt l31.1.2. Tnh cht ho hc51.1.3. Tnh cht sinh hc51.2. Vai tr v ng dng ca HA61.2.1. ng dng ca HA bt71.2.2. ng dng ca HA dng mng81.2.3. ng dng ca HA dng xp91.2.4. ng dng ca HA dng composit121.3. Tnh hnh nghin cu vt liu HA121.3.1 Trn th gii121.3.2 Nghin cu v ng dng HA Vit Nam131.4. Cc phng php tng hp HA141.4.1. Phng php t151.4.1.1. Phng php kt ta161.4.1.2. Phng php sol - gel171.4.1.3. Phng php phun sy191.4.1.4 Phng php siu m ho hc201.4.1.5. Phng php composit211.4.1.6. Phng php in ho221.4.1.7. Phng php thu nhit (ho nhit)251.4.2. Phng php kh271.4.2.1. Phng php phn ng pha rn271.4.2.2. Phng php ho - c271.4.2.3. Mt s phng php vt l281.5. Mt s phng php nghin cn vt liuHA301.5.1. Phng php nhiu x tia X (X - Ray Diffraction, XRD)301.5.2. Phng php ph hng ngoi (Fourier Transformation InfraredSpectrophotometer, FTIR)341.5.3. Phng php hin vi in t361.5.3.1. Phng php hin vi in t qut (Scanning ElectronMicroscopy, SEM)361.5.3.2. Phng php hin vi in t truyn qua (TransmissionElectron Microcopy, TEM)37CHNG II: THC NGHIM392.1 Dng c, thit b v ho cht392.1.1 Dng c392.1.2 Thit b392.1.3 Ho cht392.2 Nghin cu quy trnh tng hp bt HA392.3 Kho st nh hng canhit 412.4 Kho st nh hng catc cp axit412.5 Kho st nh hng canng cht phn ng422.6 Kho st nh hng cadung mi422.7 Kho st nh hng catc khuy trn422.8 Kho st s b nh hng ca sng siu m432.9 Chun b mu phn tch43CHNG III..........................45KT QU V THO LUN453.1 Quy trnh tng hp HA453.2 Kho st nh hng ca nhit46a. Thnh phn pha46b. Kt qu phn tch XRD47c. nh SEM v TEM49d. Kt qu o FTIR523.3 Kho st nh hng ca tc cp axit54a. Kt qu XRD55b. Kt qu nh SEM58c. Kt qu FTR593.4 Kho st nh hng ca nngcht phn ng61a. Ket qu phn tch XRD61b. Kt qu nh SEM63c. Kt qu FTIR643.5 Kho st nh hng ca dungmi66a. Ket qu phn tch XRD66b. Ket qu chp SEM68c. Kt qu phn tch FTIR693.6 Kho st nh hng ca tc khuytrn70a. Kt qu phn tch XRD70b. Kt qu chp SEM72c. Kt qu phn tch FTIR733.7 Kho st nh hng ca sng siu m74a. Ket qu phn tch XRD75b. Kt qu chp nh TEM76KT LUN77TI LIU THAM KHO782- Gorg c nh6 - Detector3- Gng di ng7 - Computer4- B phn chia chm sng8 - Bt t ghiBt HA c phn tch FTIR xc nh s c mt ca cc nhm chc: OH', C032', HP042', P043'. Bc sng c trung cho cc nhm chc c th c mt trong bt HA c trnh by bng sau: