Efficient capture of lead ions from aqueous solution by the functional covalent organic framework materials

Lead is one of the most common harmful metals in aqueous solutions. It has become an urgent need to devise a method that can effectively remove Pb(II) from aqueous solutions. In this paper, a novel covalent organic framework adsorbent was synthesized by post-modification method to remove Pb(II) from aqueous solution. This adsorbent analyzed by adsorption isotherms, kinetic and thermodynamic studies shows that the adsorption is chemically monolayer and controlled by intraparticle diffusion. The whole adsorption process is an exothermic and spontaneous reaction process. The maximum adsorption capacity of the adsorbent for Pb(II) can reach 359.94 mg/g at 298 K and the optimum pH 4. The zeta and density functional theory suggest that the electrostatic and coordination interactions between N, O and S functional groups and Pb(II) play a key role in the adsorption process. The selectivity and reproducibility results showed that this adsorbent was capable of targeted removal of Pb(II) from a polyionic environment and maintained a high adsorption efficiency after 5 cycles. In conclusion, this adsorbent has a very good application in the removal of metal ions from aqueous solutions.