Adsorption behavior and mechanism of MnMgAl-layered double hydroxide for the removal of V(V): Experiments and DFT calculation

MnMgAl-layered double hydroxide (MnMgAl-LDHs) was prepared by a coprecipitation method to treat vanadium (V(V)) pollution in solution. To reveal the influence of various factors on the adsorption effect, batch experiments were carried out. The results show that the removal rate of V(V) with 0.05 g MnMgAl-LDHs reached 87.60 %, which was significantly greater than that of MgAl-LDHs (36.60 %). The initial pH of the solution and the presence of coexisting anions (such as CO 3 2- , HPO 4 2- , and SO 4 2- ) influenced the adsorption effect. The pseudo-second-order kinetic equation fitted well with the adsorption process , indicating that the adsorption was a chemical reaction. The results of isothermal adsorption tests showed the adsorption proceeded smoothly. A variety of material characterization methods were adopted to explain the structural characteristics and chemical composition of the adsorbent before and after the reaction. To further elucidate the adsorption mechanism, the stability and electronic structure were analyzed based on density functional theory (DFT). Mn and hydroxyl groups were the main active sites, and the mechanisms were mainly redox and complexation. The phenomenon of the enhanced adsorption effect of MnMgAl-LDHs was confirmed from a microscopic perspective. In addition, the binding effect of MnMgAl-LDHs with different anions was simulated, which provided a theoretical basis for the treatment of complex anion pollution. This study combines experiments and theoretical calculations, which not only improves the scientific nature of the conclusions but also provides ideas for future adsorbent design optimization and V(V) wastewater treatment .