Photocatalytic and antimicrobial activity of gum Karaya polymer-g-C₃N₄ nanosheets reinforced ZnO/SiO₂ hydrogel for azo dyes degradation and environmental toxicity evaluation.

Industrial dye pollution presents significant environmental challenges, highlighting the need for effective and sustainable remediation strategies. In this study, a novel gum karaya (KG) polymer-based composite hydrogel containing g-C₃N₄, ZnO, and SiO₂ was synthesized via radical polymerization method to evaluate its photocatalytic, antimicrobial activity, and environmental toxicity. The KGM-ZnO-g-C₃N₄-SiO₂ hydrogel was thoroughly characterized using various analytical techniques, including XRD, FTIR, DRS-UV, XPS, FE-SEM, EDX, HR-TEM, LC-MS, PL, and photoelectrochemical (EIS) properties. EDX and XPS analysis defined the chemical composition and the phase purity of KGM-ZnO-g-C₃N₄-SiO₂ hydrogel. The composite hydrogel exhibited excellent photocatalytic activity under visible light, degrading the trypan blue (TPB) and Congo red (CR) dyes by 92.22% and 89.70%, respectively. The study examined several factors that affect photocatalytic activity, including catalyst dosage, effect of pH, the influence of inorganic ions, radical trapping analysis, and the reusability and stability of the catalyst. The composite hydrogel achieved a degradation efficiency of 80.03 % after four consecutive cycles. The intermediate products formed during TPB and CR degradation were analyzed using LC-MS analysis. A preliminary environmental toxicity assessment using the ECOSAR predictive model indicated a minimal ecological risk associated with the photocatalytic process. Additionally, the synthesized composite hydrogel demonstrated significant antibacterial activity against various pathogenic bacteria using the well-diffusion method. The polymer composite hydrogel exhibits significant potential as a sustainable, multifunctional material for environmental remediation and antimicrobial applications across various industries.