Synthesis of high-performance arsenic-specific adsorption microspheres using iron-magnesium modified chitosan

Chitosan (CS) is widely recognized for its excellent gelling properties; however, its application in heavy metal removal is often limited by the scarcity of active adsorption sites. In this study, CS was employed as a matrix material to fabricate gel beads (Fe/Mg-CS) through cross-linking with Fe³⁺ and Mg²⁺ thereby enhancing its adsorption capacity for As(V). The Fe/Mg-CS adsorbent was thoroughly characterized, and its adsorption performance was evaluated under optimized conditions. The optimal dosage of Fe/Mg-CS was determined to be 0.06 g/L, with effective adsorption observed within a pH range of 3–7. Kinetic analysis revealed that the adsorption process followed a pseudo-second-order model, suggesting that the adsorption mechanism primarily involves complexation reactions between hydroxyl groups and As(Ⅴ). Isotherm studies indicated that the Langmuir model provided the best fit, with a maximum adsorption capacity of 147.49 mg/g. Compared to conventional powdered adsorbents, Fe/Mg-CS offers several advantages, including straightforward synthesis, ease of recycling, and high efficiency. These properties make Fe/Mg-CS a promising candidate for the remediation of As(V)-contaminated groundwater, providing a sustainable and effective solution for future water purification applications.