Properties and mechanism of V(Ⅴ) removal by mussel shells loaded with nano zero-valent iron

Aiming at the environmental pollution problems caused by vanadium-containing wastewater produced by mining, metallurgy, petroleum refining, and other industries, this study prepared mussel shells loaded nano-zero-valent iron composites(nZVI@CMS) by liquid-phase reduction method using pyrolyzed mussel shell powder(CMS) as the carrier. The morphology and structure of nZVI@CMS were characterized by SEM, TEM, XRD, BET, FT-IR and XPS. The adsorption performance of V(Ⅴ) on nZVI@CMS was investigated by batch adsorption experiments, and the adsorption mechanism of V(Ⅴ) on nZVI@CMS was analyzed using adsorption kinetics, adsorption isotherm, and adsorption thermodynamics. The results showed that nZVI@CMS was a loose and porous chain sphere-like structure containing a variety of oxygen-containing functional groups. The maximum adsorption of V(Ⅴ) by nZVI@CMS was 149.33 mg/g under the conditions of nZVI@CMS dosage of 0.05 g/L, initial pH=7, V(Ⅴ) concentration of 20 mg/L, solution volume of 100 mL, and temperature of 25 ℃. The adsorption of V(Ⅴ) by nZVI@CMS could be fitted by Langmuir adsorption isotherm equation and pseudo second-order reaction kinetic equation, and it was a spontaneous heat adsorption process. The main mechanisms of V(Ⅴ) removal by nZVI@CMS included adsorption, reduction, and co-precipitation. This study turned the mussel shells into treasure, and provided a new idea for the efficient treatment of V(Ⅴ) in wastewater.