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.