Efficient Removal of Antimony (III, V) from Contaminated Water by Amino Modification of a Zirconium Metal–Organic Framework with Mechanism Study

The adsorption performance of the amino modification of zirconium metal–organic framework (UiO-66­(NH₂)) for the removal of antimony (Sb) from aqueous solution has been investigated. The influence of equilibrium concentration, solution pH, temperature, and contact time on the Sb adsorption were investigated by the batch method. Compared with original UiO-66, the UiO-66­(NH₂) adsorption capacity for Sb­(III) and Sb­(V) increased to 61.8 mg/g and 105.4 mg/g for Sb­(III) and Sb­(V), although the surface area of UiO-66­(NH₂) decreased from 486.31 m²/g to 113.46 m²/g. The adsorption equilibrium data of Sb on UiO-66­(NH₂) fitted well with the Langmuir adsorption model, and the kinetics data fitted well with the second-order adsorption model. Thermodynamic parameters indicated that adsorption processes of Sb were feasible, endothermic, and spontaneous. The adsorption isotherm parameters indicated that the Sb adsorption data fitted well with the Langmuir model. The mean adsorption energy obtained from the Dubinin–Radushkevich (D–R) isotherm model further revealed that the Sb adsorption process was chemisorption. Additionally, FTIR analysis and X-ray photoelectron spectroscopy (XPS) study revealed that the Zr–O bond and amino group played a significant role in the Sb removal. Thus, UiO-66­(NH₂) is a promising candidate for Sb contaminated water remediation on the basis of low-cost, easy availability, high Sb adsorption capacity, nontoxicity, and high stability