Adsorption behavior and mechanism of p-arsanilic acid on a Fe-based metal–organic framework.

[Display omitted] • MIL-88A adsorbent were synthesized under different conditions. • Activated MIL-88A adsorbent has excellent adsorption capacity for p -ASA. • The adsorption kinetics and isotherms follow pseudo-second-order and Langmuir models. • Coordination and hydrogen bonding dominate the adsorption process. Organic arsenic pollutant p -arsanilic acid (p -ASA) in wastewater can be converted into highly toxic inorganic arsenic under natural conditions, causing serious harm to the environment and human health. In this study, an Fe-based metal – organic framework (MOF) material, activated MIL-88A, was synthesized as an adsorbent to remove p -ASA in water. Various influencing factors in the material synthesis process, including temperature, time, solution, and annealing process, were investigated to obtain the optimal reaction conditions. The synthesized activated MIL-88A had great porosity and excellent adsorption capacity for p -ASA in a wide pH range (3 ∼ 10). When the pH of the solution was 6, the activated MIL-88A achieved a great adsorption capacity of 813 mg·g−1 for the p -ASA solution with an initial concentration of 0.334 mmol·L−1. In addition, it still had excellent adsorption capacity after 4 times of repeated usage and washing. The adsorption kinetics of p -ASA on the activated MIL-88A followed the pseudo-second-order models, and the adsorption isotherms can be fitted by the Langmuir models well. The adsorption behavior was spontaneous and endothermic, and was dominated by Fe-O-As coordination and hydrogen bonding. [ABSTRACT FROM AUTHOR]