Synthesis and Application of Biodegradable Cellulose Hydrogels From Sunflower Husks as a Water‐Retaining Material in Agriculture

ABSTRACT The water shortage is currently a major problem for agriculture around the world, and this, in turn, can negatively impact food safety. Therefore, in this article, acrylamide monomer (AAm) was bound by the cross‐linking agent N, N′‐methylene‐bis‐acrylamide (MBA) in amounts of 10, 15, and 20 mg along with microcrystalline cellulose (MCC) obtained from sunflower seed husk (SFH) and a biodegradable hydrogel in the soil layer with high sorption capacity was synthesized. As a result of the study, the AAm monomer found to be attached to the MCC matrix via intermolecular hydrogen bonds. The kinetics of swelling of the obtained hydrogels in aqueous, electrolytic and water‐ethanol, water‐acetone binary solutions at various amounts of cross‐linking agent were comparatively studied, and it was found that the water sorption potential of the natural polymer—MCC‐based hydrogel (MCC hydrogel)—is high at pH = 6.5 and corresponds to the pH of the soil environment. The study showed that the synthesized hydrogel is optimal when using 10 mg of a cross‐linking agent, has mechanical strength, withstands pressure up to 27 MPa, completely decomposes at 796°C, and has good thermal stability. It has been established that the pore sizes of hydrogel with 10 mg of cross‐linking agent lie within the range of 313.9 nm‐den 3.41 μm and belong to mesoporous materials, where the degree of swelling is 1176%. The MCC hydrogel was saturated with water from the soil within 5 days and collapsed within 35 days, releasing the absorbed water back into the soil, losing 66% of its mass and undergoing biological decomposition. These properties of MCC hydrogel allow it to be used as a “water‐retaining material” in agriculture.