Removal of iron impurities from kaolin using Bacillus Cereus siderophores

The presence of iron impurities can affect the quality of kaolin, influencing its whiteness, morphology, and its refractory properties. Conventional methods such as physical and chemical processes for iron removal from kaolin have a negative impact on the environment. Therefore, this study emphasized an environmentally friendly approach using siderophores produced by Bacillus cereus to effectively remove iron from kaolin. The research focused on the extraction and purification of siderophores from B. cereus UKMCC1150 under optimal conditions. The effectiveness of siderophores in eliminating iron impurities from kaolin is then determined. The research methodology included the extraction of siderophores and cell-free supernatant, partial purification of siderophores, and bioleaching of kaolin using cell-free supernatant and partially purified siderophores. Subsequently, the whiteness index of kaolin samples is analyzed, and the percentage of iron removal is determined based on EDX analysis. The siderophore assay results demonstrated that B. cereus can produced a high quantity of siderophores, approximately 92.42 ± 0.02% siderophore units. The presence of catecholate-type siderophores is identified through the formation of a peak at 420 nm in the FeCl3 assay. Furthermore, kaolin treated with partially purified siderophores shown an increased whiteness index by 2.11 ± 0.01%, highlighting the potential of siderophores in enhancing the quality of kaolin. EDX analysis indicated the removal efficiency of Fe(III), where kaolin treated with partially purified siderophores has a higher removal rate compared to kaolin treated with cell-free supernatant (79.17 ± 0.02% and 20.83 ± 0.01%). SEM analysis revealed significant changes in the surface morphology of kaolin after bioleaching. Overall, this study demonstrated the ability of B. cereus to produce siderophores with characteristics that have the potential to improve whiteness and effectively remove iron impurities from kaolin.