Effect of pH values on the extracellular polysaccharide secreted by Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

Abstract

The pH value plays an important role in the bioleaching of sulphide minerals. The effect of pH values on the extracellular polysaccharide secreted by Acidithiobacillus ferrooxidans was investigated in different phases of bacterial growth during chalcopyrite bioleaching. It is found that extracellular polysaccharide secretion from the cells attached to chalcopyrite is more efficiently than that of the free cells in the bioleaching solution. Three factors, pH values, the concentration of soluble metal ions, and the bacterial growth and metabolism, affect extracellular polysaccharide secretion in the free cells, and are related to the bacterial growth phase. Extracellular polysaccharide secretion from the attached cells is mainly dependent on the pH value of the bacterial culture.

Keywords

chalcopyrite / bioleaching / polysaccharides / acidity / Acidithiobacillus ferrooxidans

References

[1] Watling HR. The bioleaching of sulphide minerals with emphasis on copper sulphides: a review. Hydrometallurgy, 2006, 84(1–2): 81.

[2] Pradhan N, Nathsaram KC, Rao K S, Sukla LB, Mishra BK. Heap bioleaching of chalcopyrite: a review. Miner. Eng., 2008, 21(5): 355.

[3] Klauber C. A critical review of the surface chemistry of acidic ferric sulphate dissolution of chalcopyrite with regards to hindered dissolution. Int. J. Miner. Process., 2008, 86(1–4): 1.

[4] Vilcáez J, Yamada R, Inoue C. Effect of pH reduction and ferric ion addition on the leaching of chalcopyrite at thermophilic temperatures. Hydrometallurgy, 2009, 96(1–2): 62.

[5] Hiroyoshi N, Kitagawa H, Tsunekawa M. Effect of solution composition on the optimum redox potential for chalcopyrite leaching in sulfuric acid solutions. Hydrometallurgy, 2008, 91(1–4): 144.

[6] Wang YG, Su LJ, Zhang LJ, Zeng WM, Wu JZ, Wan LL, Qiu GZ, Chen XH, Zhou HB. Bioleaching of chalcopyrite by defined mixed moderately thermophilic consortium including a marine acidophilic halotolerant bacterium. Bioresour. Technol., 2012, 121, 348.

[7] Brierley JA. Acidophilic thermophilic archaebacteria: potential application for metals recovery. FEMS Microbiol. Lett., 1990, 75(2–3): 287.

[8] Gómez E, Ballester A, Blázquez ML, González F. Silver-catalysed bioleaching of a chalcopyrite concentrate with mixed cultures of moderately thermophilic microorganisms. Hydrometallurgy, 1999, 51(1): 37.

[9] Sand W, Gehrke T. Extracellular polymeric substances mediate bioleaching/biocorrosion via interfacial processes involving iron (III) ions and acidophilic bacteria. Res. Microbiol., 2006, 157(1): 49.

[10] Yu RL, Zhong DL, Miao L, Wu FD, Qiu GZ, Gu GH. Relationship and effect of redox potential, jarosites and extracellular polymeric substances in bioleaching chalcopyrite by acidithiobacillus ferrooxidans. Trans. Nonferrous Met. Soc. China, 2011, 21(7): 1634.

[11] Pogliani C, Donati E. The role of exopolymers in the bioleaching of a non-ferrous metal sulphide. J. Ind. Microbiol. Biotechnol., 1999, 22, 88.

[12] Gehrke T, Hallmann R, Sand W. Importance of exopolymers from Thiobacillus ferrooxidans and Leptospirillum ferrooxidans for bioleaching. Biohydrometallurgical Processing, 1995, 1, 2

[13] Gehrke T, Telegdi J, Thierry D, Sand W. Importance of extracellular polymeric substances from Thiobacillus ferrooxidans for bioleaching. Appl. Environ. Microbiol., 1998, 64(7): 2743

[14] Kinzler K, Gehrke T, Telegdi J, Sand W. Bioleaching: a result of interfacial processes caused by extracellular polymeric substances (EPS). Hydrometallurgy, 2003, 71(1–2): 83.

[15] Yu RL, Liu J, Chen A, Zhong DL, Li Q, Qin WQ, Qiu GZ, Gu GH. Interaction mechanism of Cu²⁺, Fe³⁺ ions and extracellular polymeric substances during bioleaching chalcopyrite by Acidithiobacillus ferrooxidans ATCC2370. Trans. Nonferrous Met. Soc. China, 2013, 23, 231.

[16] Yu RL, Ou Y, Tan JX, Wu FD, Sun J, Miao L, Zhong DL. Effect of EPS on adhesion of Acidithiobacillus ferrooxidans on chalcopyrite and pyrite mineral surfaces. Trans. Nonferrous Met. Soc. China, 2011, 21(2): 407.

[17] Zeng WM, Qiu GZ, Zhou HB, Liu XD, Chen M, Chao WL, Zhang CG, Peng JH. Characterization of extracellular polymeric substances extracted during the bioleaching of chalcopyrite concentrate. Hydrometallurgy, 2010, 100(3–4): 177.

[18] Karkhanis YD, Zeltner JY, Jackson JJ, Carlo DJ. A new and improved microassay to determine 2-keto-3-deoxyoctonate in lipopolysaccharide of gram-negative bacteria. Anal. Biochem., 1978, 85(2): 595.

[19] Yu RL, Tan JX, Gu GL, Hu YH, Qiu GZ. Mechanism of bioleaching chalcopyrite by Acidithiobacillus ferrooxidans in agar-simulated extracellular polymeric substances media. J. Cent. South Univ. Technol., 2010, 17(1): 56.