Swelling Properties of Superabsorbent Hydrogels Based on Carboxymethyl Cellulose With Silica, Kaolin, and Bentonite Particles for Agricultural Applications

Abstract

This study reports the preparation of carboxymethyl cellulose (CMC)-based hydrogels crosslinked with citric acid and reinforced with inorganic additives (silica, kaolin, and bentonite) for agricultural applications. The optimized composition—CMC (1 g), bentonite (1.2 g), kaolin (0.8 g), citric acid (3% w/w relative to CMC), and polyethylene glycol (0.17 g)—achieved a swelling ratio of approximately 412 g/g in distilled water and retained about 65% of its absorbed water after 5 h. Among the additives, silica exhibited the highest swelling capacity, while the combined use of bentonite and kaolin in the optimized hydrogel enhanced structural stability and long-term water retention. Characterization by SEM, EDX, UV–Vis, and FTIR confirmed successful crosslinking and additive incorporation. The biodegradable hydrogels demonstrate potential for improving soil moisture retention and reducing irrigation frequency in agricultural use.