Engineered Magnetic-Functionalized Carbon Xerogels for Sustainable Arsenic Removal: Bridging Adsorption Efficiency with Regenerability.

This study developed iron-oxide-functionalized carbon xerogels for enhanced arsenic adsorption to mitigate global water contamination. The composites were synthesized by integrating magnetite nanoparticles (15-20 nm) into a resorcinol-formaldehyde matrix via sol-gel polycondensation, followed by controlled pyrolysis. Key parameters-magnetite/resorcinol ratios (0.03-0.07), carbonization conditions (temperature, heating rate, duration), and H2O2-induced surface modification-were optimized to maximize adsorption performance. Characterization (SEM/EDX, XRD, FTIR, BET, TEM) confirmed uniform magnetite dispersion (~5 wt%) and revealed that pyrolysis at 850 °C enhanced porosity (378.8 m2/g surface area) and refined surface chemistry. Adsorption kinetics followed Elovich (R2 = 0.9396) and Power Function (R2 = 0.9443) models, indicating chemisorption dominance. Response Surface Methodology optimized desorption parameters using a Central Composite Design with three factors and two center points with repetition. A kinetic study of As(V) desorption from carbon xerogels was conducted, yielding optimal conditions: 1.0 M KOH, 160 rpm agitation, and 90 min contact time. The adsorbent retained >88% regeneration efficiency over four cycles, demonstrating robust reusability. Synergistic effects of magnetite incorporation, tailored pyrolysis, and H2O2 modification significantly improved arsenic selectivity and capacity in complex matrices, while enabling magnetic recovery.