Comparative Study of Cellulose and Methylcellulose Grafted with Acrylic Acid-Based Hydrogels for Enhanced Soil Water Retention and Nitrogen Fertilizer Delivery

Abstract

Grafting of cellulose (CE) and methylcellulose (MC) with acrylic acid (AA) represent a promising way to enhance soil water retention as well as to transfer fertilizers in a controlled manner to plants. For the purpose of comparison, hydrogels were prepared from cellulose and methylcellulose by grafting them with acrylic acid, (CE-g-AA) and (MC-g-AA). For the purpose of mechanically strengthening them, they were cross-linked with N, N- methylenebisacrylamide (MBA). The following techniques were used to characterize the prepared hydrogels include FT-IR, TGA, XRD, FESEM, and EDS. The degree of swelling of the hydrogels was studied, through which it can determine the suitability of each hydrogel for use in the appropriate place, where the swelling can regulate the loading and releasing behaviors of hydrogel microspheres. As a result, it was observed the (CE-g-AA)/MBA hydrogel, due to its high degree of swelling, is suitable for loading water and help the soil retain water. While (MC-g-AA)/MBA hydrogel, because its swelling is weaker, is suitable for carrying fertilizer, where it was actually loaded with nitrogen fertilizer model KNO3, and its maximum loading percentage (Lmax %) = 19.3%. The study involves studying soil saturation with water and then water retention in soil, where the (CE-g-AA)/MBA hydrogel soil sample has retained water for 19 days compared to 13 days only for controlled sample. The release profile of KNO3-loaded (MC-g-AA)/MBA copolymer hydrogel after choosing three pHs medium for release includes pH 4, pH 7, and pH 9, it was found to be more regular and regulated at pH 7.