Magnetic mesoporous carbon as excellent adsorptive material for arsenic removal from aqueous environment

A magnetic mesoporous carbon (MC) with high functionality was fabricated by direct thermolysis and carbonization of bimetallic metal–organic frameworks (M/Fe–MOF, where M = La³⁺ or Zr⁴⁺). The as-prepared materials such as La–Fe@MC and Zr–Fe@MC displayed excellent adsorption performance towards the removal of arsenite and arsenate ions in an aqueous solution. The physicochemical properties of prepared adsorbents before and after adsorption were characterized by using various analytical techniques. Various influencing parameters such as contact time, solution pH, co-existing anion, and regeneration experiments were analyzed to determine the maximum adsorption capacity for both arsenic species using the as-synthesized adsorbents. The La–Fe@MC composite showed a higher adsorption capacity for both contaminants when compared to Zr–Fe@MC composite and the maximum monolayer adsorption capacity of As(III) and As(V) ions were 116.25 and 166.67 mg/g for La–Fe@MC and 109.89 and 144.93 mg/g for Zr-Fe@MC, respectively. The Langmuir isotherm and pseudo-second-order kinetic models were the optimum fit for As(III) and As(V) species adsorption on both the adsorbents. The magnetic La–Fe@MC and Zr–Fe@MC materials exhibited excellent reusability even after five adsorption cycles. This study provides significant insights into the development of promising candidates for eliminating As(III) and As(V) ions from aqueous solutions.