PVA/AMPS hydrogels: Promising adsorbents for wastewater treatment with high efficiency and reusability

A PVAMPS hydrogel was synthesized through chemical cross-linking and semi-interpenetration of Poly (vinyl Alcohol) (PVA) and 2-Acrylamido-2-methyl-1-propanesulfonic acid (AMPS) with glutaraldehyde in distilled water. Various ratios of PVA/AMPS, namely PVAMPS-1 (2:1), PVAMPS-2 (1:1), and PVAMPS-3 (1:2), were examined to understand their individual impacts on gel formation. The synthesis of hydrogels was confirmed using FT-IR and solid-state ¹³C NMR spectroscopy. The PVAMPS hydrogels demonstrated high efficiency as a selective adsorbent for removing cationic dyes, such as Methylene Blue, Safranine-O, and Thionine, from aqueous solutions, with over 90% removal of cationic dyes observed within 18 hours. Regeneration and reusability studies revealed that even after four cycles, the adsorption capacity of the PVAMPS hydrogels remained exceptionally high, with removal rates exceeding 90% for Methylene Blue. However, for Safranine-O and Thionine, the removal rates dropped to 20% and 23%, respectively, after four cycles. These findings underscore the promising potential of PVAMPS hydrogels for the removal of cationic dyes in wastewater treatment.