Preparation and characterization of sodium alginate and silicon dioxide composites

Abstract

Sodium alginate is a natural anionic polysaccharide with good biocompatibility, biodegradability, water solubility, and film-forming ability, but its poor water resistance, limited stability, and low mechanical strength restrict its wider application. In this study, sodium alginate/silicon dioxide composites were prepared through calcium ion-induced gelation. Silicon dioxide was introduced into the sodium alginate gel network during the gel formation process to improve the structural characteristics of the alginate-based material. The effects of silicon dioxide concentration and the volume ratio of sodium alginate solution to silicon dioxide dispersion on product morphology were investigated. The results showed that the addition of silicon dioxide changed the appearance of the gel particles from semi-transparent to white, indicating the incorporation of the inorganic component. Among the tested conditions, the best morphology was obtained when 10 mg/mL sodium alginate solution and 5 mg/mL silicon dioxide dispersion were mixed at a volume ratio of 8:2. FTIR analysis showed changes in the absorption bands related to –OH, –COO⁻, and C–O groups, suggesting interactions between sodium alginate and silicon dioxide. UV–vis spectra showed a new absorption peak at approximately 473 nm, further supporting the formation of the composite material. This study provides a simple method for preparing sodium alginate-based inorganic composites.