Effective adsorption of antimony(III) by MIL-101(Cr)-NH2: influencing-factor and characterization analyses and response surface optimization

With the increasing threat antimony (Sb) pollution poses to the environment, its removal from water is becoming increasingly important. Accordingly, metal-organic frameworks (MOFs) are garnering increasing research attention owing to their excellent performance as adsorbents. Here, the MOF MIL-101(Cr)-NH 2 was prepared directly by solvothermal synthesis. Sb(III) adsorption using MIL- 101(Cr)-NH 2 was evaluated systematically at varying adsorbent dosages and pHs. And the adsorption kinetics, isotherms, and thermodynamics were explored by altering the contact time, initial Sb(III) concentration, and temperature, respectively. The results revealed that Sb(III) was adsorbed onto MIL-101(Cr)-NH 2 very quickly, even at low antimony concentrations. The maximum Sb(III) adsorption capacity of MIL-101-NH 2 is 83.61 mg g -1 . In the presence of coexisting ion (NO 3 - ), the amount of Sb(III) adsorbed was slightly increased, which may be due to the formation of an inner-sphere complex. The Box–Behnken method was used to design and optimize a response surface with reference to three main influencing factors, that is, dosage, pH, and temperature, so as to obtain a multivariate quadratic model of adsorption behavior and identify the optimal adsorption conditions. Finally, a preliminary economic analysis of the synthetic material was carried out.