Surface corrosion by microbial flora enhances the application potential of phosphate rock for cadmium remediation

Abstract Heavy metal pollution restricts the intensification of land and endangers human health through the food chain. Surface adsorption of heavy metals by soil natural minerals affects their mobility and biotoxicity, yet little is known about the fate of heavy metals after microorganisms affect the surface structure of minerals. Our study shows that ureolytic microbes corrode the surface of phosphate minerals through carbonate modification without changing their crystal structure but significantly enhancing their specific surface area. Compared with natural phosphate rock (PR), the concave surface of the flora-phosphate rock (FPR) exposes more Ca2+ exchange sites, more active functional groups, and more straightforward to release phosphates that co-precipitate with Cd2+, resulting in an approximately tenfold increase in Cd2+ adsorption. The adsorption of Cd2+ by FPR is a spontaneous endothermic single-layer adsorption, which can quickly remove Cd2+ in wastewater. FPR can also obviously change the pH of the soil by releasing phosphate to increase the stabilization effect of Cd2+. These results provide a sustainable approach to developing novel, cost-effective minerals for environmental remediation and contribute to understanding the function and role of microorganisms in immobilizing heavy metals at the mineral interface.