Highly efficient As(V) removal from acid mine drainage by biomineralization of composite Schwertmannite and jarosite: Adsorption behavior and mechanism

The biomineralization of Schwertmannite and jarosite provides a green remediation approach for the removal of heavy metal(loid)s from acid mine drainage (AMD),but the removal mechanism of As(V) by phase-transformed minerals under pH fluctuations remains unclear. This study investigated the effects of initial pH values (2.5 and 3.8) on mineral phase transformations and compared them with chemically synthesized minerals to reveal the specific As(V) removal mechanism of phase-transformed minerals. The results indicated that with the change of pH, the biominerals evolved into a composite mineral of schwertmannite and jarosite, whose specific surface area is nearly 10 times higher than that of chemically synthesized minerals. The removal of As(V) was achieved through a dual mechanisms of hydroxyl complexation and SO42– ligand exchange, and the adsorption behavior followed a pseudo-second-order kinetic model. The initial pH regulated the composition of the composite mineral. The composite mineral mainly composed of jarosite(pH=3.8) showed a higher As(V) removal rate (up to 94.67%). This study elucidates the correlation between pH-regulated biomineralization phase transformation and heavy metal(loid) removal, providing theoretical support and new insights for the development of AMD remediation technologies.