pH Responsive Moringa Gum‐ and Pectin‐Based Hydrogel: A Low‐Cost Polysaccharide Biosorbent for the Adsorption of Crystal Violet Dye

ABSTRACT The current research work aims to synthesize pH‐responsive hydrogel networks of moringa gum (MG)‐pectin via in air (IA) method. Different analytical methods like Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), SEM, and x‐ray diffraction (XRD) are accustomed to confirming the formation of hydrogel. The natural polysaccharides MG and pectin (PEC) were chosen as backbones for synthesis. The free radical polymerization method was employed using monomer acrylamide (Aam) and MBA ( N , N ′‐methylenebisacrylamide) as a cross‐linker. The hydrogel is optimized using various parameters such as backbone ratio, volume of solvent, temperature, time, pH of reaction mixture, concentration of monomer, concentration of cross‐linker, and initiator. The optimized hydrogel network exhibits a swelling percentage of 400.8% at pH 7 and temperature 60°C at solvent 24 mL, backbone ratio (1:1), concentration of cross‐linker (0.003243 mol L −1 ), initiator (0.00555 mol L −1 ), and monomer (0.07034 mol L −1 ). Additionally, adsorption studies were conducted for crystal violet (CV) dye. The optimum adsorption was achieved at an adsorbent amount 0.5 g at 2 mg L −1 dye concentration and pH of 12 at 20°C. The kinetics of adsorption showed that adsorption follows pseudo‐first‐order kinetics and best fitted data with Langmuir isotherm, indicating monolayer adsorption process. Endothermic and spontaneous processes are suggested by thermodynamics findings. Thus, the synthesized hydrogel is a potential candidate for dye removal from wastewater solutions and an excellent environment‐friendly adsorbent.