Chloride intercalated Ni-Al layered double hydroxide for effective adsorption removal of Sb(Ⅴ)

Abstract

Antimony is a new type of pollutant with potential toxicity and carcinogenicity. Therefore, the restoration of antimony-contaminated water has attracted wide attention from all over the world. In this research, we synthesized chloride intercalated Ni-Al layered double hydroxide (Ni-Al LDH) with a good laminated structure by co-precipitation and ion exchange. We investigated the adsorption performance of Ni-Al LDH for Sb(V) in a one-component system for the first time through a series of batch experiments. The effect of key process variables, such as pH, reaction temperature, adsorbent dosage, contact time and initial concentration on the adsorption was studied in single-factor experiments separately. The reaction rapidly reached adsorption equilibrium within 30 min and it maintained the antimony removal rate at about 91% at the optimum reaction conditions. Multiple models were applied to fit the adsorption isotherm, kinetic and thermodynamic data to describe the adsorption behaviors of Sb(V) on Ni-Al LDH. A perfect fit between the Langmuir model and isothermal adsorption experimental data confirmed a maximum adsorption capacity of material could be up to 142.86 mg/g. SEM-EDS, XPS, and other characterization analyses demonstrated that ion exchange and ligand exchange are the primary mechanisms for triggering the adsorption process. It proved the excellent regeneration performance of the material by data from five stable adsorption/desorption cycles. It could be demonstrated that Ni-Al LDH could be an applicable adsorbent for the removal of Sb(V) .