Enhancing the stability of soil contaminated with fluoride through the utilization of pristine and aluminium-impregnated biochar: a comprehensive mechanistic approach

The effect of trivalent metal-modified biochar on the stability and mitigation of fluoride ions (F^-) in contaminated soils remains largely unexplored, despite biochar’s extensive application in F^--contaminated soil. The mineral metal-modified biochar has the potential to serve as an efficient solution for soil contaminated with F^-. In this study, pristine-pinecone biochar (P-BC) and AlCl₃-modified pinecone biochar (A-BC) were synthesized and then utilized to remediate the soil that had been contaminated with F^-. Both P-BC and A-BC efficiently immobilized F^- within the contaminated soil. Further examinations through sequential extraction procedure and subsequent analysis using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and elemental dot mapping demonstrated a transformation of F^- into a more stable state by A-BC treatment of the contaminated soil. This implies that A-BC may possess the capacity to function as an efficient ameliorant for immobilizing F^- within the soil.