Preparation and properties of modified cassava starch slow-release hydrogel with acid and alkali resistance

Slow release of chlorine dioxide is receiving increasing attention in the field of environmental disinfection. This study focuses on the binary solid dioxide rate to improve its acid and alkali resistance. Cassava starch hydrogels were prepare as the backbone and polyvinyl alcohol (PVA) as the soft segment and were modified by adding quaternized carboxymethyl cellulose and chitin to make the hydrogel acid- and alkali- resistant. Subsequently, sodium bicarbonate was introduced to make the hydrogel porous, thereby solving the problem whereby binary solid chlorine dioxide is corroded by acid and alkali during the slow-release process of chlorine dioxide, thus resulting in poor mechanical properties. The chemical structure and morphology of the cassava starch-based composite hydrogels were confirmed by solid-state nuclear magnetic resonance and other methods. Measurements of the compressive properties with different pH solutions demonstrated the acid and alkali resistance of the modified hydrogel was the strongest at pH= 3.5 and pH= 10.5 with compressive stresses of 200.47 kPa and 180.65 kPa. The cumulative chlorine dioxide release curves were in good agreement with the first-order kinetic model, and R2 values were all greater than 0.95. This research offers broad applications in environmental disinfection, fruit and vegetable preservation, and wastewater adsorption.