Zeng, G., Ping, Y., Xu, H. et al. Transformation of As and Cd associated with Fe–Mn-modified biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More during simultaneous remediation on the contaminated soil. Environ Sci Pollut Res(2024). https://doi.org/10.1007/s11356-024-34384-6

Researchers applied Fe- and Mn-modified biochar (BC-Fe–Mn) to stabilize arsenic (As) and cadmium (Cd) in contaminated soil, achieving removal efficiencies of 60.8% for NaHCO3-extractable As and 49.6% for DTPA-extractable Cd. Speciation analyses indicated that stabilization occurred through transformation to low-crystallinity Fe-bound As and Fe–Mn oxide-bound Cd. Correlation analyses showed a positive association between increased As in Fe-bound fractions and Mn oxide fractions (r = 0.64), and between Cd in oxide fractions and Fe (r = 0.91) and Mn (r = 0.76). A novel dialysis experiment isolated the reacted biochar, revealing crystalline compounds (Fe0.67Mn0.33)OOH and Fe2O3 on its surface, identified by SEM–EDS and XRD. FTIR analyses indicated potential reaction sites for As and Cd on BC-Fe–Mn. A crystalline MnAsO4 compound was found in treated soil. These findings enhance understanding of As and Cd stabilization mechanisms by BC-Fe–Mn and support large-scale applications.