Controlled release and release kinetics studies of boron through the functional formulation of carboxymethyl tamarind kernel gum-based superabsorbent hydrogel

The novel Boron micronutrient-loaded superabsorbent hydrogel (BSH) was synthesized via in situ mechanism having carboxymethyl tamarind kernel gum (CMTKG) as its principle component. The synthesis was established by thermal gravimetric analysis examination, scanning electron microscopy micrographs studies, and Fourier transform infrared analysis. The influence of various solvents, such as standard saline solution, different pH solutions (4, 9, 12), and distilled water on the swelling degree of BSH, was examined. Out of all the mentioned solvents, the highest swelling degree was noticed by the distilled water (465 g/g). The BSH was also examined for the agricultural application to assess the release of the boron micronutrient. It was established by studying and calculating the release behavior pattern along with the release kinetics of BSH in water, and as well in soil. It is significant to note that in soil, BSH exhibited 20.07% for the 1st day which notably increased to 76.17% on the 80th day. Release kinetic studies suggested that the Korsmeyer–Peppas model fitted the best out of all the models used, in the case of water, which also revealed that the release of boron from BSH was independent of the polymeric network as it followed Fickian diffusion mechanism. However, in the case of soil, the release was observed to follow the Higuchi model. The half-life and time period for the release of 95% and 99% were calculated as per the Olson’s single exponential model, to predict the pattern of boron release from developed BSH formulation. Release time for 99% boron in the soil, 274 days (with a half-life of 38 days), was found higher than in water, 9.33 days (with a half-life of 1.29 days). Thus, moisture-retaining BSH also successfully revealed slow boron release behavior.