Development of biodegradable gum guggul-based hydrogel as an efficient moisture-retaining agent for agricultural applications

We prepared guggul gum-based hydrogel (GgG-cl-poly(AA)) through a free radical graft copolymerization mechanism in this work. The preparation was carried out using ammonium persulfate as an initiator, acrylic acid as the monomer, and N, N′-methylenebisacrylamide as the crosslinker. The synthesized hydrogel’s swelling capacity and equilibrium swelling ratio were thoroughly investigated by optimizing various reaction parameters: reaction time, solvent volume, microwave power, crosslinker amount, initiator concentration, and monomer concentration. The swelling results demonstrated that the synthesized hydrogel can attain a maximum percentage swelling of 980% within 3 h in an aqueous solution. The prepared hydrogel sample was characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscopy, nuclear magnetic resonance, and thermogravimetric analysis. The prepared hydrogel was studied for water retention behavior in the soil, water absorbance in the open air at room temperature, reswelling studies, and resistive swelling studies in various salt solutions at different temperatures and pH values. Notably, the crosslinked hydrogel exhibited a reduced swelling capacity across various salt solutions compared to the aqueous solutions. The biodegradation studies were examined in both soil burial and vermicomposting methods for two months, revealing a maximum biodegradation of 95.65% through the vermicomposting method and 87.7% through the soil burial method. The results indicate that the crosslinked hydrogel based on guggul gum is a potential candidate for various agricultural applications.