Optimisation of bioleaching of Malaysian and Chinese Kaolin

Lee, Wei Sheong (2023) Optimisation of bioleaching of Malaysian and Chinese Kaolin. Final Year Project, UTAR.

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Abstract

Kaolin has impurities such as iron which led to reduced quality, brightness and viability in industrial applications. Therefore, iron extraction was developed to increase the quality of kaolin. The bioleaching method could be an alternative to produce good quality kaolin as bacteria, being an organic compound is environmental friendly. But before bioleaching can be implemented as an alternative, it needs to be optimised to a feasible efficiency of at least 80 %. Hence, optimisation of bioleaching of kaolin is necessary. It was found that the optimum nutrients condition for bioleaching kaolin with B. cereus is 8 g/L of glucose concentration while for B. megaterium and B. aryabhattai the optimum glucose concentration is 10 g/L. Iron reduction ability of Bacillus bacteria was measured and reduction of iron was clearly visible in phenanthroline analysis and ICP-OES analysis whereby the Fe(II) concentration increased during the period of 10 days of bioleaching. The EDX analysis revealed that a slightly higher bioleaching efficiency was achieved as compared to the previous studies. Malaysian kaolin treated with B. cereus, B. megaterium and B. aryabhattai was found to be 57.4 %, 60.3 % and 65.9 % respectively. Whereas for Chinese kaolin treated with B. cereus, B. megaterium and B. aryabhattai, the bioleaching efficiency was found to be 41.6 %, 54.7 % and 62.8 % respectively. Optimum glucose concentration used for the bioleaching experiment could be the contributing factor to the small increase in the bioleaching efficiency. Malaysian and Chinese kaolin experienced changes in terms of structure and surface morphology after bioleaching with Bacillus spp. bacteria based on the SEM analysis. The surface structure of both Malaysian and Chinese kaolin changed from amorphous to a more crystalline structure while the chemical composition and bonds of both Malaysian and Chinese kaolin remains unchanged after bioleaching as determined in the XRD and FTIR analysis. The results showed improvements in the bioleaching efficiency, contributing to the studies of implementing bioleaching in the industrial scale. With more laboratory scale experiments of optimisation, bioleaching will be able to replace chemical leaching with a lower cost and sustain and protect the environment.

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