Facile Preparation of Poly(AA-co-NaAMPS) Hydrogels Toward Toxic Dyes and Heavy Metals Removal via Frontal Polymerization

Wastewater treatment contributes to the sustainable utilization of water resources for alleviating water scarcity. The application of polymeric materials as adsorbents for eliminating hazardous substances in water has garnered extensive attention owing to their remarkable adsorption efficiency, stability, and selectivity. Herein, a facile strategy is provided to rapidly synthesize poly(acrylic acid-co-sodium 2-acrylamide-2-methylpropanesulfonate) (poly(AA-co-NaAMPS)) hydrogels with exceptional adsorptive capacity via frontal polymerization (FP). The FP processes are meticulously examined in terms of initiator dosage and monomer ratio. The as-prepared hydrogels demonstrate pH-responsive swelling ability and pH-dependent adsorption capacity for various dyes and heavy metal ions. Compared with traditional batch polymerization (BP), the hydrogels prepared by FP exhibit superior swelling and adsorption abilities. Additionally, research on the adsorption mechanism for both dyes and heavy metal ions is conducted by fitting the adsorption kinetic data both with Langmuir and Freundlich equations. The maximum adsorption capacity (q _m ) of hydrogels derived from Langmuir model for dyes of methylene blue (MB) and rhodamine B (RB) is, respectively, 595.3 and 3078.5 mg g⁻¹, while for heavy metal ions of Cr³⁺ and Cd²⁺ is, respectively, 1010.8 and 1191.3 mg g⁻¹. This research exploits an alternative approach for the rapid preparation of high-efficiency hydrogel adsorbents toward wastewater treatment.