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A study of the vanadium species in an acid leach solution of stone coal using ion exchange resin
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A study of the vanadium species in an acid leach solution of stone coal using ion exchange resin Li Zeng ⁎, Qinggang Li, Lianshen Xiao, Qixiu Zhang Metallurgical Science and Engineering School, Central South University, Changsha 410083, China abstract article info Article history: Received 1 May 2010 Received in revised form 4 July 2010 Accepted 5 July 2010 Available online 15 July 2010 Keywords: Stone coal Sulphuric acid leach Vanadium species Ion exchange The species of vanadium extracted by a weak base anion resin D314 from sulphuric acid leach solution of stone coal was investigated. The saturated adsorption capacity of vanadium on the resin was found to be up to 501 mg/mL wet resin with a distribution ratio of 950 at pH = 3–4 and 15 °C using static adsorption method. Vanadium was adsorbed in the form of V 10 O 28 6 − and HV 10 O 28 5 − . The study provides the theory and fundamental basis for the industrial application of weak base resins for extraction of vanadium from acid leach solution of stone coal. © 2010 Elsevier B.V. All rights reserved. 1. Introduction In a previous study (Zeng et al., 2009), a weak base resin D314 was used to selectively extract vanadium from the leach solution of stone coal. The study indicated that the application of the resin process for the extraction of vanadium from stone coal was feasible and promising. The present work investigates the adsorption capacities of the resin D314 for vanadium from the sulphuric acid leach solution of stone coal. Based on the calculated adsorption capacities, the species of vanadium extracted and the optimum adsorption of vanadium on the resin are determined. This provides the theory and fundamental basis to the industrial application of the resin. 2. Materials and methods 2.1. Materials A solution containing vanadium, similar to the actual solution in industry, was synthesized. The pH of the synthetic solution was around 1–13. The weak base anion exchange resin D314 with a function group of [–N(CH 3 ) 2 ] and structure of cross-linking acrylate was obtained from Hangzhou Zhengguang Chemical Company of China. The diameter of more than 95% resin beads was in the range of 0.45–1.00 mm. The resin was used in a thermostatic heater for batch adsorption experiments. 2.2. Methods The resins were soaked in distilled water for 24 h before use. To investigate the functional group concentration and total exchange capacity of the D314 resin, 5 mL resin was contacted with 50 mL H 2 SO 4 or HCl solution in a thermostatted magnetically beaker at 15 °C for 24 h and stirred at 400 r/min. The effects of pH and temperature on the loading capacity and distribution ratio of vanadium on the resin were studied by mixing 1 or 2 mL resin with 100 mL synthetic solution each time with a stirring speed of 400 r/min for 24 h at 15 °C. The V concentration (V 2 O 5 ) in the feed solution was 6.3 mmol/L. Samples were collected after filtration and analyzed to determine the concentration of vanadium by titration with ammonium ferrous sulphate. 3. Results and discussion It is reported that the species of vanadium existing in an aqueous solution depend on not only its valence but also its concentration and the pH value (Bailor, 1973; Zhang and Shen, 1991; Gupta and Krishnamurthy, 1992; Ho et al., 1994; Rakib and Durand, 1996). Fig. 1 is the species of vanadium (V) existing in an aqueous solution under different pH and concentration (Charles et al., 1986). It can be seen from Fig. 1 that the cationic vanadium species are predominant at pH b 2. Polynuclear anionic species are predominant in the pH range of 2–9, while mononuclear anionic species dominate at pH N 9. In the acid leach solution of stone coal containing 2–3 g/L V 2 O 5 at pH 2–4, vanadium is mostly in the forms of V 10 O 28 6 − , HV 10 O 28 5 − and H 2 V 10 O 28 4 − . However, the loading Hydrometallurgy 105 (2010) 176–178 ⁎ Corresponding author. E-mail address: [email protected] (L. Zeng). 0304-386X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.hydromet.2010.07.001 Contents lists available at ScienceDirect Hydrometallurgy journal homepage: www.elsevier.com/locate/hydromet
Transcript of A study of the vanadium species in an acid leach solution of stone coal using ion exchange resin
Hydrometallurgy 105 (2010) 176–178
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A study of the vanadium species in an acid leach solution of stone coal using ionexchange resin
Li Zeng ⁎, Qinggang Li, Lianshen Xiao, Qixiu ZhangMetallurgical Science and Engineering School, Central South University, Changsha 410083, China
⁎ Corresponding author.E-mail address: [email protected] (
0304-386X/$ – see front matter © 2010 Elsevier B.V. Adoi:10.1016/j.hydromet.2010.07.001
a b s t r a c t
a r t i c l e i n f oArticle history:Received 1 May 2010Received in revised form 4 July 2010Accepted 5 July 2010Available online 15 July 2010
Keywords:Stone coalSulphuric acid leachVanadium speciesIon exchange
The species of vanadium extracted by a weak base anion resin D314 from sulphuric acid leach solution ofstone coal was investigated. The saturated adsorption capacity of vanadium on the resin was found to be upto 501 mg/mL wet resin with a distribution ratio of 950 at pH=3–4 and 15 °C using static adsorptionmethod. Vanadium was adsorbed in the form of V10O28
6− and HV10O285− . The study provides the theory and
fundamental basis for the industrial application of weak base resins for extraction of vanadium from acidleach solution of stone coal.
L. Zeng).
ll rights reserved.
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
In a previous study (Zeng et al., 2009), a weak base resin D314was used to selectively extract vanadium from the leach solution ofstone coal. The study indicated that the application of the resinprocess for the extraction of vanadium from stone coal was feasibleand promising. The present work investigates the adsorptioncapacities of the resin D314 for vanadium from the sulphuric acidleach solution of stone coal. Based on the calculated adsorptioncapacities, the species of vanadium extracted and the optimumadsorption of vanadium on the resin are determined. This providesthe theory and fundamental basis to the industrial application ofthe resin.
2. Materials and methods
2.1. Materials
A solution containing vanadium, similar to the actual solution inindustry, was synthesized. The pH of the synthetic solution wasaround 1–13. The weak base anion exchange resin D314 with afunction group of [–N(CH3)2] and structure of cross-linking acrylatewas obtained from Hangzhou Zhengguang Chemical Company ofChina. The diameter of more than 95% resin beads was in the range of0.45–1.00 mm. The resin was used in a thermostatic heater for batchadsorption experiments.
2.2. Methods
The resins were soaked in distilled water for 24 h before use. Toinvestigate the functional group concentration and total exchangecapacity of the D314 resin, 5 mL resin was contacted with 50 mLH2SO4 or HCl solution in a thermostatted magnetically beaker at 15 °Cfor 24 h and stirred at 400 r/min. The effects of pH and temperature onthe loading capacity and distribution ratio of vanadium on the resinwere studied by mixing 1 or 2 mL resin with 100 mL syntheticsolution each time with a stirring speed of 400 r/min for 24 h at 15 °C.The V concentration (V2O5) in the feed solution was 6.3 mmol/L.Samples were collected after filtration and analyzed to determine theconcentration of vanadium by titration with ammonium ferroussulphate.
3. Results and discussion
It is reported that the species of vanadium existing in anaqueous solution depend on not only its valence but also itsconcentration and the pH value (Bailor, 1973; Zhang and Shen,1991; Gupta and Krishnamurthy, 1992; Ho et al., 1994; Rakib andDurand, 1996). Fig. 1 is the species of vanadium (V) existing in anaqueous solution under different pH and concentration (Charleset al., 1986).
It can be seen from Fig. 1 that the cationic vanadium species arepredominant at pHb2. Polynuclear anionic species are predominantin the pH range of 2–9, while mononuclear anionic speciesdominate at pHN9. In the acid leach solution of stone coalcontaining 2–3 g/L V2O5 at pH 2–4, vanadium is mostly in theforms of V10O28
6− , HV10O285− and H2V10O28
4− . However, the loading
Fig. 1. Equilibrium predominance diagram for VV-OH− species as a function ofconcentration and pH.
0
0.001
0.002
0.003
0.004
0.005
0.006
0 42 6 8 10 12 14pH
Sat
urat
ed a
dsor
ptio
n ca
paci
ty(m
ol/m
L w
et r
esin
)
Fig. 2. Effect of pH on the saturated adsorption capacity of vanadium on D314 resin.
177L. Zeng et al. / Hydrometallurgy 105 (2010) 176–178
capacity of vanadium on resin D314 depends on the vanadiumpolynuclear species and anionic charge. For example, the adsorp-tion of vanadium by the resin can be expressed by the followingreaction:
5R2⋅SO4 + 2HV10O5−28 = 2R5⋅HV10O28 + 5SO2−
4 : ð1Þ
3.1. The calculated exchange capacity of resin
The results in Table 1 show that the measured exchange capacitywas 2.97 and 2.88 mmol/mL wet resin in H2SO4 and HCl respectively.Therefore, the maximum loading capacity of vanadium on the resincan be calculated based upon the speciation and anionic charge aslisted in Table 2.
Table 1The measured exchange capability of resin.
Acid Concentration of H+ (mol/L) Theory exchange capacity(mmol/mL wet resin)
Before exchange After exchange
H2SO4 2.336 2.039 2.97HCl 1.820 1.532 2.88
Table 2Calculated loading capacity of vanadium on the resin at different pH.
pH Vanadiumspeciation
Vanadium:charge ratio
Calculated loading capacity(mmol/mL wet resin)
b2 V2O5·H2O – –
VO2+
2–6 HV10O285− 2:1 5.94
H2V10O284− 2.5:1 7.43
6–8 V10O286− 1.67:1 4.96
V3O93− ; H2VO4
− 1:1 2.978–12 V3O9
3− 1:1 2.97V2O7
4− ; HVO42− 1:2 1.49
N12 V2O74− 1:2 1.49
VO43− 1:3 0.98
3.2. The effect of pH on the loading capacity of vanadium on the resin
Fig. 2 shows that the saturated adsorption capacity of vanadium onD314 resin was around 5 mmol/mLwet resin in the pH range of 2.5–4.5and decreased at pHb2 and pHN4.5. Based on the different saturatedadsorption capacities of vanadium, the species of vanadium adsorbedby D314 resin at different pH values can be inferred.
For example, at pH 3.2, vanadium exists in the solution in the formsof V10O28
6− , HV10O285− and H2V10O28
4− . Considering the vanadium:chargeratio, 1 mol of functional groups on the resin exchanges and adsorbs2.5 mol V as H2V10O28
4− in comparison to 2 mol V as HV10O285− and
1.67 mol V asV10O286− , respectively. Since the saturated loading capacity
of vanadium on the resin at pH 3.2 is 5.4 mmol/mL wet resin, which is1.82 times of the functional group concentration (Table 1), it can bereadily inferred that vanadium was largely absorbed in the forms ofV10O28
6− and HV10O285− . Likewise at pH 4.46, the saturated loading
capacity of vanadium was 5.5 mmol/mL wet resin and the adsorbedvanadium speciation is the same. The lower vanadium loading at higherpH can be attributed to a change in speciation and vanadium:chargeratio.
Based on the discussion above, the maximum loading capacity ofthe resin for vanadium can be inferred to reach 556 mg/mL wet resin(based on V2O5) in the pH range of 2.5–4.5. In the experiment, theloading capacity of vanadium was 492 mg V2O5 at pH 3.2 and 501 mgV2O5 at pH 4.46, respectively, which is in good agreement with that ofinference.
3.3. The effect of pH on the distribution ratio of vanadium with D314resin
The vanadium concentrations (V2O5) in solution before and afterexchange are shown in Table 3. As seen, the best pH range foradsorption of vanadium on the resin was between 3–4 where thedistribution ratio reached 950. It can also be seen that vanadium washardly adsorbed by D314 resin under the condition of strong acid orbase. This is because, at very low pH, vanadium exists dominantly inthe form of VO2
+ that cannot be adsorbed by theweak base anion resin,
Table 3Effect of pH on the distribution ratio of V with D314 resin.
EquilibriumpH value
V concentration in the solution (mol/L) Distributionratio
Before exchange After exchange
1.22 0.0025 0.0021 192.31 0.0063 0.0017 2703.10 0.0063 0.0006 9504.27 0.0063 0.0010 5306.51 0.0063 0.0018 2508.11 0.0051 0.0019 16812.01 0.0025 0.0022 13
Table 4Effect of temperature on the distribution ratio of V with D314 resin.
Temperature 15 °C 25 °C 35 °C 45 °C
Equilibrium pH value 4.27 4.09 4.30 4.04V concentration in the solutionwhen in equilibrium
0.0010 0.0008 0.0004 0.0005
Distribution 530 688 1475 1160
178 L. Zeng et al. / Hydrometallurgy 105 (2010) 176–178
which is normally applied in the acid or neutral solution. At high pH,the resin has no ion exchange capacity.
3.4. The effect of temperature on the distribution of vanadium withD314 resin
It can be seen from Table 4 that temperature is one of theimportant factors on the distribution ratio of vanadiumwith the resin.The adsorption of vanadium on the resin is performed best at 35 °Cwith a distribution ratio of 1475.
4. Conclusions
(1) The measured exchange capacity of D314 resin is around3 mmol/mL wet resin.
(2) The saturated adsorption capacity of vanadium on the resin isup to 5.5 mmol/mL wet resin (501 mg V2O5/mL wet resin) atpH 4.46. Vanadium is largely adsorbed by the resin in the formsof V10O28
6− andHV10O285− at pH 3–4.5 which gives themaximum
loading of vanadium.(3) The maximum distribution ratio of vanadium with the resin is
1475 at pH 4.30 and 35 °C.
References
Bailor, J.C., 1973. Comprehensive Inorganic Chemistry, vol. 3. Pergamon Press, Oxford,pp. 519–521.
Charles, F., Baes Jr., Mesmer, Robert E., 1986. The Hydrolysis of Cations. Robert E KriegerPublishing Company, Malabar, Florida.
Gupta, C.K., Krishnamurthy, N., 1992. Extraction Metallurgy of Vanadium. ProcessMetallurgy Series, vol. 8. Elsevier, Amsterdam.
Ho, E.M., Kyle, J., Lallenec, S., Muir, D.M., 1994. Recovery of vanadium from spentcatalysts and alumina residues. In: Monhemius, J., et al. (Ed.), Hydrometallurgy '94Conference Proceedings: Inst. Min. Metall., London, pp. 1105–1122.
Rakib, M., Durand, G., 1996. Study of complex formation of vanadium (V) with sulphateions using a solvent extraction method. Hydrometallugy 43, 355–366.
Zeng, L., Li, Q.G., Xiao, L.S., 2009. Extraction of vanadium from the leach solution of stonecoal using ion exchange resin. Hydrometallurgy 97, 194–197.
Zhang, Q.L., Shen, P.W., 1991. Titanium, Vanadium and Chromium. Inorganic ChemistrySeries, vol. 8. Science Press, Beijing. 238 pp. (In Chinese).
