Fabrication of Adsorption-Reactive Composite PAM-AMPS/Fe3O4 Hydrogel Based on Persulfate Advanced Oxidation Processes for Organic Pollutants Degradation

The catalytic materials for sulfate radical-based advanced oxidation processes with the performance of high activity and stable had attracted significant attention in the field of sustainable wastewater treatment. Here, a novel adsorption-reactive composite catalyst with Fe3O4 impregnated acrylamide-based hydrogel (PAM-AMPS/Fe3O4) was designed and synthesized for methylene blue (MB) degradation based on persulfate advanced oxidation processes. For the acrylamide-based hydrogel, the monomer of 2-acrylamide-2-methyl-propanesulfonic acid (AMPS) was added to improve the adsorption performance of the composite, and the maximum adsorption capacity of the selected hydrogel was about 40 mg/g. In the presence of the persulfate activated system, the degradation efficiency of MB of PAM-AMPS/Fe3O4 was significantly increased to a level of 94% in 20 min. This value was far superior to catalytic systems without the AMPS. This outstanding performance was benefiting from the synergetic effects of reduced aggregation of Fe3O4 combined with the enhanced adsorption capacity of PAM-AMPS hydrogel. Their cooperative function promoted oxidative decomposition of MB. In addition, PAM-AMPS/Fe3O4 exhibited a good stability and reusability, and it could maintain high degradation efficiency and activity after three successive cycling tests. And at the same time, the produced dominate oxidizing species for MB degradation in the system were identified as SO4 & BULL;- by the radical quenching experiments. This work laid a foundation for applying PAM-AMPS/Fe3O4 as a highly efficient and stable catalyst for future applications and provided new insights into the design and synthesis of environmentally benign and inexpensive persulfate activators.