The Development of Fe₃O₄-Monolithic Resorcinol-Formaldehyde Carbon Xerogels Using Ultrasonic-Assisted Synthesis for...

Inorganic arsenic in drinking water from groundwater sources is one of the potential causes of arsenic-contaminated environments, and it is highly toxic to human health even at low concentrations. The purpose of this study was to develop a magnetic adsorbent capable of removing arsenic from water. Fe₃O₄-monolithic resorcinol-formaldehyde carbon xerogels are a type of porous material that forms when resorcinol and formaldehyde (RF) react to form a polymer network, which is then cross-linked with magnetite. Sonication-assisted direct and indirect methods were investigated for loading Fe₃O₄ and achieving optimal mixing and dispersion of Fe₃O₄ in the RF solution. Variations of the molar ratios of the catalyst (R/C = 50, 100, 150, and 200), water (R/W = 0.04 and 0.05), and Fe₃O₄ (M/R = 0.01, 0.03, 0.05, 0.1, 0.15, and 0.2), and thermal treatment were applied to evaluate their textural properties and adsorption capacities. Magnetic carbon xerogel monoliths (MXRF600) using indirect sonication were pyrolyzed at 600 °C for 6 h with a nitrogen gas flow in the tube furnace. Nanoporous carbon xerogels with a high surface area (292 m²/g) and magnetic properties were obtained. The maximum monolayer adsorption capacity of As(III) and As(V) was 694.3 µg/g and 1720.3 µg/g, respectively. The incorporation of magnetite in the xerogel structure was physical, without participation in the polycondensation reaction, as confirmed by XRD, FTIR, and SEM analysis. Therefore, Fe₃O₄-monolithic resorcinol-formaldehyde carbon xerogels were developed as a potential adsorbent for the effective removal of arsenic with low and high ranges of As(III) and As(V) concentrations from groundwater.