Preparing conductive polymer-based adsorbent with better cupric ion adsorption efficiency by monomer precursor cross-linking method

Conductive polymer-based adsorbents have showed excellent heavy metal ion removing capabilities. Crosslinking modification is one of the feasible methods to further improve their properties. To make use of the advantages of monomer precursor method over the polymer precursor method in forming dense interpenetrating networks, and then optimizing the surface structure of materials and providing more adsorption sites, the mesoporous cross-linked poly-o-phenylenediamine (M-CR-PoPD) prepared by using the former one and used in removing Cu2+ from aqueous solution. The FTIR results showed that the monomer was successfully crosslinked and polymerized. The loosely packed target product with a hierarchical pore structure distribution was successfully formed. The maximum adsorption capacity of 105.18 mg g−1 was obtained at 25 °C after 3 h of adsorption when M-CR-PoPD prepared at the reaction time of 6 h using anhydrous ethanol as solvent and trimethylolpropane-tris(3-aziridinyl) propionate as crosslinking agent. This value reached the optimum Cu2+ removal capability of reported PoPD-based adsorbents. According to EDX, FTIR, and XPS data before and after adsorption, the possible adsorption mechanism based on the cation-π interaction and the formation of Cu–N bonds was proposed. These results could help develop more effective conductive polymer-based adsorbents to remove Cu2+ from wastewater.