Removal of Organic Dyes from Aqueous Solutions by Adsorption of Chitosan-Guar Gum-Based Glyoxal Crosslinked Hydrogel

In this study, the natural polysaccharides chitosan and guar gum-based hydrogel crosslinked with glyoxal was synthesized to examine the efficacy of organic dye removal by adsorption. The maximum swelling capacity of 815% was achieved by optimization studies. The synthesis of hydrogel was proved by the analyses involving XRD, FT-IR, FESEM, and EDS techniques. The adsorption effectiveness of a CH-gl-GG-based hydrogel was examined by adsorbing cationic model dyes Malachite Green (MG) and Auramine O (AO) under various reaction parameters (e.g., dye solution concentration, temperature, adsorption time, and pH). Adsorption equilibrium data showed excellent fit to the Langmuir model for MG (R-2 = 0.99) and AO (R-2 = 0.99). The adsorption kinetics study indicated that the removal process for both the dyes would be better described by the pseudo-second-order kinetic model. The thermodynamic study demonstrated the spontaneous and endothermic nature of MG and AO dye adsorption. The maximal adsorption capacity (q(m)) was found to be 40.69 mg/g for MG while 30.51 mg/g for AO. In summary, the CH-gl-GG hydrogel has shown its potential as an environment-friendly and efficient adsorbent for the adsorption of cationic dyes from contaminated water.