Design, preparation and properties of ionic polymer adsorbents containing sulfonic acid and triazine structures

In order to further enhance the adsorption performance of polymer adsorbents for cationic dyes, a series of ionic porous polymer adsorbents (SAIPP-x) containing sulfonic acid and triazine structures were designed and prepared using melamine, benzidinebisulfonic acid, and terephthalaldehyde as starting materials. It is found that the ion exchange capacity (IEC) and specific surface area of the representative SAIPP-4 with 20% benzidinedisulfonic acid content are 1.55 mmol/g and 7.49 m2/g, respectively. Its maximum adsorption capacity for Methylene Blue (MB) reached 197.96 mg/g, and could maintain more than 80% of its initial adsorption capacity after 6 cycles. Its adsorption behavior conformed to the pseudo-second-order kinetics and the Freundlich model, and was a multi-layer adsorption mechanism dominated by chemical adsorption. The strong electrostatic interaction and hydrogen bond synergistic effect between the sulfonic acid group and the cations in MB were the main adsorption mechanisms. The synergistic introduction of moderate ion capacity and intrinsic porosity is an effective method to improve the performance of polymer adsorbents.