Removal of Zn(II) and Co(II) from N,N-dimethylformamide by polyamidoamine dendrimers decorated silica: Performance and mechanism

The presence of metal ion in N,N-dimethylformamide (DMF) would bring adverse effect for its practical application in the fields of chemical industry and advanced functional materials. Adsorbents for the effective metal ion purification in DMF are needed. Herein, amino-capped polyamidoamine (PAMAM) dendrimer decorated silica particles (G1.0-SG, G2.0-SG, and G3.0-SG) were prepared for removing of Zn(II) and Co(II) from DMF. The influence effects on the adsorption performance were revealed. The adsorption mechanism was indicated by density functional theory (DFT) calculation. The maximum adsorption amount of G1.0-SG, G2.0-SG and G3.0-SG for Zn (II) are 0.35, 0.42 and 0.38 mmol.g(-1), while those for Co(II) are 0.31, 0.36 and 0.22 mmol.g(-1), respectively. The adsorption is proceeded with film diffusion process as rate-controlling step and can be well depicted by the pseudo-second-order model. Adsorption isotherm reveals the adsorption can be enhanced by the metal ion concentration and temperature. The adsorption was conducted spontaneously in chemical mechanism by monolayer behavior. Theoretical calculation reveals the chelation between primary and second amino groups with metal ion dominates the adsorption. The adsorbents can be efficiently regenerated by thiourea-HNO3 solution. As the adsorbents exhibit good adsorption performance and regeneration property, they can be potentially used for the purification of metal ion in DMF solvent with practical application. (C) 2020 Elsevier B.V. All rights reserved.