Enhanced Pb²⁺ adsorption performance of coal gangue modified by Bacillus megaterium (CG-W)

Coal gangue is the main solid waste generated during the mining and processing of coal. Its resource utilization is a pressing issue that needs to be addressed urgently at present. Meanwhile, lead pollution has become one of the major environmental challenges faced by global soil and water bodies. This study utilized the bacterium (Bacillus megaterium) to conduct microbial modification of coal gangue, with the aim of enhancing its application performance in the remediation of heavy metal pollution. By evaluating the tolerance of the strain to different Pb²⁺ concentrations, the adsorption behavior of the modified coal gangue (CG-W) was systematically investigated, and the adsorption mechanism was revealed by combining techniques such as XRD, XPS and FT-IR. The results show that Bacillus megaterium can still grow normally under the condition of 800 mg/L Pb²⁺, demonstrating a high tolerance; the modified coal gangue achieved a removal rate of 94% for Pb²⁺ under the optimal adsorption conditions (initial pH 6, temperature 40°C, and time 60 min) with an initial Pb²⁺ concentration of 200 mg/L. Under the optimal modification conditions (bacterial concentration of 5.88×10¹²CFU/mL, load temperature of 30 °C, and coal gangue pH of 6.0-8.0), the repair mechanism mainly results from the complexation effect of extracellular polymers secreted by microorganisms on Pb²⁺, as well as the ion exchange process involving mineral components. This study provides an effective approach for the resource utilization of coal gangue and the treatment of heavy metal pollution.