Experimental Investigation of Arsenic (III, V) Removal from Aqueous Solution Using Synthesized α-Fe2O3/MCM-41 Nanocomposite Adsorbent

Adsorption of arsenic (III, V) from aqueous solution onto the synthesized α-Fe2O3/MCM-41 nanocomposite adsorbent, as function of contact time, initial concentration of the solution, temperature, pH, and presence of other anionic species, has been investigated. Characterization of adsorbent was performed via XRD, FT-IR, TGA, TEM, and N2 adsorption–desorption techniques. The synthesized adsorbent belonged to the group of mesoporous materials with the mean pore diameter of 2.37 nm, specific surface area of 507.5 m2 g−1, and total pore volume of 0.571 cm3 g−1. The experimental data were analyzed by Langmuir, Freundlich, and Dubinin-Radushkevich (D–R) adsorption isotherms. Based on Langmuir isotherm, the maximum adsorption capacities at 298 K in the concentration range of 2–200 ppm were 133.3 and 102.1 mg g−1 for As(ш) and As(v), respectively. The adsorption experiments at different contact times indicated that the kinetics of adsorption accurately followed the pseudo-second-order rate equation. Thermodynamics parameters were calculated, and it was found that the adsorption process was spontaneous, exothermic, and favored at lower temperatures. The capability of regeneration and reusability of adsorbent was also examined in alkaline solutions.