Adsorption performance of silica supported polyamidoamine dendrimers for Cd(II) and Cu(II) in N,N-dimethylformamide

• Silica supported PAMAM dendrimers were synthesized for adsorption Cd(II) and Cu(II) form DMF. • Adsorption kinetic can reach equilibrium within 240 min and obeys pseudo-second-order model. • Adsorption isotherm obeys Langmuir model with spontaneous, endothermic and chemical nature. • Adsorption mechanism was demonstrated by DFT calculation. N, N-dimethylformamide (DMF) plays an important role in chemical industry and materials science. The intrusion of metal ions during the production, storage and transportation affects the purity of DMF and brings adverse effects to its practical use. Hence, silica supported polyamidoamine (PAMAM) dendrimers (SG/G1, SG/G2 and SG/G3) were synthesized and recruited for the adsorption of Cd(II) and Cu(II) from DMF solution. The influence factors were determined and the adsorption mechanism was demonstrated base on theoretical calculation. The adsorption amount for the ions decreases by the order of SG/G2 > SG/G3 > SG/G1. Adsorption kinetic can reach equilibrium within 240 min and obeys pseudo-second-order kinetic model. Adsorption isotherm indicates that high temperature and metal ion concentration can promote the adsorption. The adsorption process is spontaneous, endothermic and chemical adsorption in nature and it can be described by Langmuir model. Theoretical calculation reveals that the adsorption mainly took place by forming tetra-coordinated complex via two tertiary amino N and two carbonyl O atoms and metal ions.