Experimental and DFT study of Cu(II) removed by Na-montmorillonite

The experimental and theoretical studies on the adsorption of Cu(II) on the surface of Na-montmorillonite (Na-Mt) were reported. Effects of batch adsorption experimental parameters were studied. Density functional theory (DFT) and molecular dynamics (MD) simulations were used to study the adsorption of Cu(II) on montmorillonite(001) surface. The adsorption reached equilibrium within 80 min and the adsorption capacity was 35.230 mg middot g(-1 )at 25 degrees C. The adsorption data of Cu(II) were consistent with pseudo-second-order kinetic and Langmuir isotherm models. The activation energy (Ea) was 37.08 kJ middot mol(-1), which implied the nature of physical adsorption. The thermodynamic experiment illustrated that the adsorption was a spontaneous endothermic behavior. The influence of coexisting cations on the adsorption capacity of Cu(II) was Mg(II) > Co(II) > Ca(II) > Na(I). The simulation results demonstrated that there were no significant differences in the adsorption energy of Cu(II) at the four adsorption sites on the montmorillonite(001) surface. Cu(II) had more electron transfer than Na(I). The diffusion coefficient of Cu(II) in the aqueous solution system containing montmorillonite was 0.850 x 10(-10) m(2) middot s(-1). A considerable amount of Cu(II) ions were adsorbed at a distance of 0.257 and 2.25 & Aring; from the montmorillonite(001) surface. The simulation results provided strong supporting evidence for experimental conclusions.

Automated summary

This study reported the experimental and theoretical studies on the adsorption of Cu(II) on Na-montmorillonite surface. The adsorption reached equilibrium within 80 min with an adsorption capacity of 35.230 mg middot g(-1) at 25 degrees C. The adsorption data of Cu(II) followed pseudo-second-order kinetic and Langmuir isotherm models. The simulation results showed no significant differences in the adsorption energy of Cu(II) at different sites on the montmorillonite surface, and Cu(II) had more electron transfer than Na(I).