Modeling of Swelling and pH-Dependent Nutrient Release Kinetics of HPC/CMC/Alginate Hydrogel Blends for Agricultural Applications

Abstract

The swelling and nutrient release behaviors of a novel hydrogel blend of hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), and sodium alginate (NaAlg) was investigated to determine its applicability as an agricultural soil conditioner. Hydrogel swelling and nutrient release data were obtained over time at varying temperatures and pH conditions. The experimental data were fit into the power law, Tsai and Strieder, and Johansson’s models to determine the kinetic parameters for the swelling behavior and nutrient release. Under the experimental swelling conditions, the maximum and minimum swelling capacities of the hydrogel blend were 322.9245% and 228.0483%, respectively. The data fit to the power law suggested that a pseudo Fickian behavior describes the diffusion mechanism. The data fit to the Tsai and Strieder and Johansson’s models provided the experimental values for the α and temperature correlation as 3.69×10-5 and 0.0278, respectively, which implies that the diffusion behavior within the hydrogel does not vary significantly within the temperature range. Lastly, the inconsistency observed in the nutrient release behaviors at varying pH suggested that additional trials may be required in order to establish a clearer relation between pH and nutrient release behavior.