A robust biochar‐magnetite composite for rapid and sustainable arsenic removal from water: Efficiency, kinetics, health risk assessment, and reusability

BACKGROUND Arsenic (As) contamination in freshwater ecosystems remains a dire global challenge, necessitating the invention of efficient and sustainable treatment technologies. This research assesses and compares the adsorption performance of engineered biochar (BC), magnetic nanoparticles (MNPs), and a novel biochar magnetic‐nanoparticles composite (BCMNPs) for As removal. RESULTS Material characterization using FTIR, SEM, and complementary analytical techniques confirmed successful surface functionalization and structural integration within the composite. Batch adsorption studies were carried out to examine the effects of initial As concentration, sorbent dosage, pH, and contact time. BCMNPs exhibited the highest adsorption capacity (3.40 mg g −1 at pH 4), outperforming BC and MNPs individually, and achieved rapid uptake with equilibrium reached within the first hour. In continuous‐flow column experiments treating 0.5 mg L −1 As solutions, BCMNPs achieved 97% removal efficiency and retained structural integrity and performance across repeated regeneration cycles. Health‐risk assessment showed up to a 99% reduction in carcinogenic risk. The pseudo‐second‐order kinetic model and the Freundlich isotherm showed the best adsorption behavior, indicating that electrostatic interactions and hydrogen bonding primarily governed multilayer chemisorption. CONCLUSIONS The BCMNPs composite demonstrates high stability, rapid kinetics, and excellent reusability, highlighting its potential as a scalable adsorbent for As remediation in contaminated waters.