Environmentally friendly superabsorbent bio-hydrogel for agricultural soil conditioning and plant micronutrient release

A one-step superabsorbent, eco-friendly bio-hydrogel was synthesized from the bio-polymer, carboxymethyl tamarind kernel gum (CMTKG), by using the crosslinking agent epichlorohydrin. The optimized bio-hydrogel showed a swelling of ~23845% with a good reswelling of ~6217% after 5 ^th cycles at room temperature (~25 ^o C). Bio-hydrogel exhibited water retention in air for approximately 16 days. When incorporated into soil, this retention period was extended by about 48 days compared to soil without the hydrogel. The Maximum water-holding capacity of the soil was increased by ~90% compared to the control soil sample. The biodegradation study illustrated a weight loss of ~98% by 60 days. The blackberry plantation study revealed the germination rate and survival rate of 25% and 85%, respectively, more than the control soil. Molybdenum (Mo) was loaded in CMTKG-based bio-hydrogel, as a micronutrient carrier vehicle for micronutrient release as a proof-of-concept measurement. The Mo release from the bio-hydrogel showed ~86% in water after 19 days. Kinetic models study showed that the first-order model and the Peppas-Sahlin model were the best fit models, indicating that the Mo release rate is proportional to concentration with Fickian diffusion and polymer chain relaxation.