Synthesis and characterization of Hing gum-based hydrogel for enhanced removal of malachite green from aqueous solutions

This study aimed to synthesize a hydrogel based on the Hing gum, grafted with acrylamide, for the adsorption of Malachite Green (MG) dye. Graft copolymers were optimized using a full factorial model in combination with response surface methodology and microwave irradiation to achieve maximum swelling. The optimized parameters comprised an initiator concentration of [Formula: see text] [Formula: see text]mol[Formula: see text]L[Formula: see text], a monomer concentration of [Formula: see text] [Formula: see text]mol[Formula: see text]L[Formula: see text], and a solvent volume of 13[Formula: see text]mL, resulting in a maximum swelling capacity of 760%. The statistical adequacy of the model was validated through ANOVA. The synthesized hydrogel was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, zeta potential analysis, and Brunauer–Emmett–Teller theory. Its adsorption efficiency for MG dye was systematically investigated under various conditions, including contact time (1–6[Formula: see text]h), pH (2–9), adsorbent dosage (0.2–1.0[Formula: see text]g/L), and temperature (25–55[Formula: see text]C). The hydrogel demonstrated significant efficacy in eliminating cationic MG dye from aqueous solutions, achieving an adsorption rate of approximately 97% within 6[Formula: see text]h at room temperature. The adsorption efficacy was evaluated by adsorption kinetics and isotherm models. The findings demonstrated that the pseudo-second-order kinetic model and the Langmuir isotherm model provide the most accurate representation of the dye adsorption process. These findings underscore the hydrogel’s significant adsorption ability and its potential as an economical and eco-friendly method for eliminating MG dye from polluted water sources.