Oleh

Sri Juari SantosaJurusan Kimia FMIPA UGM

ACID MINEAcidity:

1.Oxidation of pyrite

FeS(s) + O2(aq) + 2 H2O(l) Fe2+(aq) + SO4

2-(aq) + 4 H+

(aq) )(24

1gO

Fe3+(aq) + SO4

2-(aq) + 3 H+

(aq) + ½ H2O(l)

2. Dissolution of humic and fulvic acids

Humic Substances are traditionally fractionated according to their solubilities

Fulvic acids: are those organic materials that are soluble in water at all pH values

Humic acids: are those materials that are insoluble at acidic pH values (pH < 2) but are soluble at higher pH values

Humin: is the fraction that is insoluble in water at all pH values

Negative Effect of Acid Mine

Attach and erode soil and minerals to result the dissolution of metals, like Fe, Cd, Mn, and Zn

Environmental pollution

Utilization of Hydrotalcite to remediate acid mine

Study on the ability of Mg/Al hydrotalcite in neutralize the acidity through

exchanging its interlayer hydroxide (OH-), carbonate (CO32-), and

bicarbonate (HCO3-) anions with polluting anions of SO4

2-, humic acid (HA),

and fulvic acid (FA) in aqueous solution

OH- H O2 CO32- HCO3

-

M , M2+ 3+

M , M2+ 3+

OH

OH

OH

OH

Hydrotalcite (layered double hydroxide anionic clay)

1) General formula: [M2+1-xM3+

x(OH)2]x+(An-)x/n . yH2O

where: M2+ is divalent cation M3+ is trivalent cation An- is interlayer anion (1-x/x) varies from 1 to 5

2) Structure:

No Name Empirical formula Crystal system Image Origin

1 BarbertoniteNot Radioactive

Mg6Cr2(CO3)(OH)16·4(H2O)Molecular Weight = 654.01 gm

Hexagonal - Dihexagonal Dipyramidal

Nevada Creek, Tasmania, Australia

2 BechereriteNot Radioactive

Zn4.5Cu1.5Zn2(OH)132(S0.75)2(Si0.25)2(O3)2(OH)Molecular Weight = 933.60 gm

Trigonal - Pyramidal

Color: Light green

Tonopah-Belmont mine, Osborne silver-gold district, Maricopa County, Arizona USA

3 Carbonate-cyanotrichite

Not Radioactive

Cu4Al2(CO3)0.66(SO4)0.34(OH)12·2(H2O)Molecular Weight = 620.53 gm

Orthorhombic Widowmaker mine, Fry Canyon, San Juan Co., Utah, USA

4 CaresiteNot Radioactive

Fe2+4Al2(CO3)(OH)12·3(H2O)

Molecular Weight = 595.49 gmTrigonal -

Trapezohedral

Poudrette quarry, Mt Saint-Hilaire, Rouville Co., Québec, Canada

5 CarrboyditeNot Radioactive

Ni10Cu4Al9(SO4)4(CO3)2(OH)43·7(H2O)Molecular Weight = 2,445.61 gm

Hexagonal Carr-Boyd Nickel Mine, Western Australia, Australia

6 ChalcoalumiteNot Radioactive

CuAl4(SO4)(OH)12·3(H2O)Molecular Weight = 525.67 gm

Monoclinic – Sphenoidal

Lavender Pit, Bisbee, Cohchise County, Arizona, USA

7 Charmarite-2H & Charmarite-3T

Not Radioactive

Mn2+4Al2(CO3)(OH)12·3(H2O)

Molecular Weight = 591.86 gmHexagonal –

Trapezohedral

Color: Orange brown, Pale brown, Pale blue, Colorless

Mt. St.-Hilaire, QUE, Canada

8 ChlormagaluminiteNot Radioactive

Mg3.5Fe2+0.5Al2(OH)12Cl(CO3)0.5·2(H2O)

Molecular Weight = 472.53 gmHexagonal Color: Colorless,

Yellow brown

Kapaev explosion pipe, Angara River, southern Siberian Platform, Russia

9 CyanotrichiteNot Radioactive

Cu4Al2(SO4)(OH)12·2(H2O)Molecular Weight = 644.33 gm

Orthorhombic Grandview mine, Grand Canyon, Coconino County, Arizona, USA

10 GlaucoceriniteNot Radioactive

Zn3Cu2Al3(SO4)1.5(OH)16·9(H2O)Molecular Weight = 982.56 gm

Trigonal Mina Serpieri, Laurium, Attiki, Greece

11 HydrombobomkuliteNot Radioactive

Ni0.75Cu0.25Al4(NO3)1.5(SO4)0.5(OH)12·14(H2O)Molecular Weight = 765.17 gm

Monoclinic Color: Sky blue Mbobo Mkulu cave, Nelspruit district, South Africa

12 HydrowoodwarditeNot Radioactive

Cu0.5Al0.5(OH)2(SO4)0.25·0.75(H2O)Molecular Weight = 116.81 gm

Trigonal – Hexagonal Scalenohedral

St Christoph Mine, Bärenhecke, Glashütte, Erzgebirge, Saxony, Germany

13 ManasseiteNot Radioactive

Mg6Al2(CO3)(OH)16·4(H2O)Molecular Weight = 603.98 gm

Hexagonal – Dihexagonal Dipyramidal

Jacupiranga mine, Jacupiranga, Sao Paolo, Brazil

14 MbobomkuliteNot Radioactive

Ni0.75Cu0.25Al4(NO3)1.5(SO4)0.5(OH)12·3(H2O)Molecular Weight = 567.00 gm

Monoclinic – SphenoidalH

Jomac Uranium mine, White Canyon, San Juan Co., Utah, USA

15 NickelalumiteNot Radioactive

Ni0.7Cu0.3Al4(SO4)1.5(NO3)(OH)12·3(H2O)Molecular Weight = 632.31 gm

Monoclinic – Sphenoidal

Color: Sky blue Mbobo Mkulu cave, eastern Transvaal, South Africa

16 Quintinite-2HNot Radioactive

Mg4Al2(OH)12(CO3)·4(H2O)Molecular Weight = 487.34 gm

Hexagonal – Trapezohedral

Jacupiranga Mine, São Paulo, Southeast Region, Brazil

17 Quintinite-3TNot Radioactive

Mg4Al2(OH)12(CO3)·4(H2O)Molecular Weight = 487.34 gm

Trigonal – Trapezohedral

Jacupiranga Mine, São Paulo, Southeast Region, Brazil

18 SpangoliteNot Radioactive

Cu6Al(SO4)(OH)12Cl·3(H2O)Molecular Weight = 797.91 gm

Trigonal – Ditrigonal Pyramidal

Blanchard mine, Bingham, Socorro County, New Mexico, USA

19 WoodwarditeNot Radioactive

Cu4Al2(SO4)(OH)12·3(H2O)Molecular Weight = 662.34 gm

Hexagonal Green River Formation, Uintah Co., Utah, USA

20 ZaccagnaiteNot Radioactive

Zn3.9Al2.1(OH)12(CO3)·3(H2O)Molecular Weight = 629.83 gm

Hexagonal – Dihexagonal Dipyramidal

Hilarion Mine, Agios Konstantinos, Lavrion District, Attikí Prefecture, Greece

21 ZincaluminiteNot Radioactive

Zn6Al6(SO4)2(OH)26·5(H2O)Molecular Weight = 1,278.62 gm

Hexagonal Kamariza Mine, Laurium, Attiki, Greece

22 ZincowoodwarditeNot Radioactive

Zn0.47Al0.38(OH)2(SO4)0.18(H2O)0.6

Molecular Weight = 103.10 gmTrigonal -

Rhombohedral

Hilarion Mine, Agios Konstantinos, Lavrion District, Attikí Prefecture, Greece

23 Zincowoodwardite-1TNot Radioactive

Zn0.66B0.3Al0.33(OH)2(SO4)0.155·0.96(H2O)Molecular Weight = 121.50 gm

Trigonal - Rhombohedral

Color: Pale blue, Bluish white

Laurion (Lavrion,Laurium), Greece

24 Zincowoodwardite-3RNot Radioactive

Zn0.5B0.33Al0.33(OH)2(SO4)0.2·0.59(H2O)Molecular Weight = 109.02 gm

Trigonal - Hexagonal Scalenohedral

Color: Pale bluish white, Bluish white

Laurion (Lavrion,Laurium), Greece

50 mL mixed solution of Mg2+

and Al 3+

NaOH 0,5 M

Synthesis of Mg/Al hydrotalcite

pH

pH

oC120

7.00

XRD

IR

Synthesis of Mg/Al hydrotalcite (continued)

Stability Test

pH3; 5; 7; 9;

11; 13

50 mL

Aquadest

0.1 g Mg/Al

hydrotalcite

Shaker bath, 2 hours

Stability Test (countinued)

oC120

mg

198

Purified Peat Soil or Humus

Humin(Insoluble fraction)

Fulvic Acid(Soluble)

Purified HumicAcid

Humic Acid(Precipitation)

Humic Substances(Soluble fraction)

Pure Humic Acid(Solid)

Humic Acid(MIBK phase)

Humic Acid(Aqueous phase)

Humin(MIBK phase)

Humic Acid & Humin(MIBK phase)

Fulvic Acid(Aqueous phase)

Peat Soil or Humus

Solvent ExtractionAlkaline Extraction

Purification

Shaking in NaOH Solvent extraction with MIBK

Ad. HClBack extractioninto NaOH

Solvent extraction with MIBK

Washing & Evap. MIBKPurification

Isolation of Humic and Fulvic Acids

Effect of Medium Acidity on the Adsorption

50 mL Humic acid 150 mg/L

pH3; 5; 7; 9; 11; 13

0.1 g Mg/Al hydrotalcite

Shaker bath, 2 hours

Effect of Medium Acidity on the Adsorption (continued)

filtrateseparation

UV-Vis 400 nm

Aads Vs pH

Rate of Adsorption

50 mL Humic acid

150 mg/L

9.00

0.1 g Mg/Al hydrotalcite

Shaker bath

minute

10, 20, 40, 60, 180, 300

Rate of Adsorption (continued)

filtrate UV-Vis 400 nm Aads Vs t

Adsorption Capacity

50 mL Humic acid

ppm120, 150, 180, 210, 240

0.1 g Mg/Al hydrotalcite Shaker bath

minute

t optimum

Adsorption Capacity (continued)

filtrate UV-Vis 400 nm Aads Vs A0

Ceq/m Vs Ceq

25 mL NaOH 0.5 M

0.01 g humic acid + Mg/Al

hydrotalcite

Desorption

minute

5, 15, 30, 60, 120

Shaker bath separation

Desorption (continued)

filtrate UV-Vis 400 nm

% Elution Vs t

Characterization of Functional Group of Humic Acid

Table Distribution of oxygen containing functional groups (meq/100 g) in humic acids isolated from widely different climatic zones

Climatic zone Tropical

Indonesia Kalimantan

Acidity Artic@ Subtropical@

South1) Central2) East3) North

Sumatera4) Central Java5)

Others@

COOH 320 420 - 520 341 424 353 322 343 380 - 450 Phenolic OH 240 210 - 250 332 288 330 298 300 210 - 570

Alcoholic OH 490 290 6 29 6 10 n.d. 20 - 490

Total 560 630 - 770 673 712 683 619 643 560 - 890 @ Stevenson, 1982 1) Gambut district 2) Barembeng village 3) Sambutan village 4) Labuhan Batu village 5) Rawa Pening n.d.: not determined

0 3 6 9 12 14

pH

Stab

ility

of

Mg/

Al h

ydot

alci

te

(%)

20

80

60

40

100

0

0.25

0.5

0.75

1

0 5 10 15

pH

Frac

tion

of a

dorb

ed a

nion

SO42-HAFA

Effect of Medium Acidity on the Adsorption of Anions on Mg/Al Hydrotalcite

The Change of Medium Acidity after the Adsorption of Anions

pH pH pH Anion

Awal Akhir Anion

Awal Akhir Anion

Awal Akhir

3.0 5.1 3.0 4.2 2.9 4.6

5.0 5.7 5.0 5.1 5.0 5.3 7.0 6.2 7.0 5.6 7.3 5.9

9.0 8.1 9.0 8.4 9.3 8.4

11.0 8.9 11.0 9.2

Fulvat-

11.3 9.0

SO42-

13.0 9.3

Humat-

13.0 9.7

Interpretation of the Adsorption Process

OH- H O2 CO32- HCO3

-

OH-

H O2

CO32-

HCO3-

M , M2+ 3+

M , M2+ 3+

OH

OH

OH

OH

+ +

Hydrotalcite Anionic sorbate (A )n- Hydrotalcite containing sorbate

Effect of Interaction Time on the Adsorption of Anions

0

20

40

60

80

100

0 30 60 90 120 150 180

t (min)

Ani

on re

mai

ned

(%)

HASO42-FA

Adsorption Capacity of Mg/Al Hydrotalcite for Humic Acid

0

40

80

120

Ads

orpt

ion

capa

city

(mg/

g)

Kaolin

clay

Fisher

PAC Darc

o G-60

ALDRICH Grap

hite p

owder

Cabot V

ulcan xc

72

Cabot M

onarc

h 1400

Cabot P

earls

2000

Carbon

Chitin

Chitosan

Mg/Al H

ydrotalci

te

Zn/A

l Hyd

rotalcit

e

0

25

50

75

100

0 60 120 180

Adsorption time (min)

%

HAFA

0 60 120 180

Desorption time (min)

HAFA

Regeneration of Mg/Al Hydrotalcite from Humic Acid

Mg/Al hydrotalcite is a very potential adsorbent for the remediation of acid mine since:

1. Easy to be synthesized2. Highly stable at wide range of medium acidity3. Highly adsorb anions occurring in acid mine4. Increasing the pH of medium to close to neutral5. Easy to be regenerated

Implication:1. Dissolution of metals from soil and minerals in acid mine may be minimized2. The desorption product may be used to ameliorant