A robust and highly compressible polyacrylamide co-polymer hydrogel developed through g-C3N4 initiated photopolymerisation and its photocatalytic activity towards dye removal

Abstract

Photocatalytic hydrogels have drawn significant interest in many research fields, including energy conversion and wastewater treatment. However many synthesized hydrogels show mechanical brittleness, which limits their practical application. Here, we have developed a simple, cost-effective, and eco-friendly synthesis method for the photopolymerisation of g-C₃N₄/polyacrylamide co-polymer hydrogel under visible light irradiation. The developed hydrogel exhibits high compressibility up to a strain of 230% with a mechanical strength of 0.55 MPa. We have addressed the dual functions of g-C₃N₄ in the hydrogel. First, as a photoinitiator and reinforcing agent in the polymerisation of a photocatalytic hydrogel. Second, as a photocatalyst embedded in the hydrogel for the degradation of organic dye pollutants. The three-dimensional network of the hydrogel allows rapid permeation of the cationic dye molecules into the hydrogel matrix, thereby accelerating the photodegradation process. The applicability of the synthesized photocatalytic hydrogel towards the selective degradation of different cationic dyes over anionic dyes has been determined. In addition, the synthesized hydrogel demonstrates recyclability for up to 5 cycles, without losing its photocatalytic properties. Along with this, the hydrogel shows adsorption maxima of 72 mg g⁻¹ towards CV dye. Thus, the simple and easy preparation of the g-C₃N₄ based hydrogel and its excellent photocatalytic and adsorption properties have proved it to be a potential photocatalytic material for green and sustainable water remediation techniques.