Chitosan-alginate sponge with multiple cross-linking networks for adsorption of anionic dyes: Preparation, property evaluation, mechanism exploration, and application

A chitosan-alginate sponge (CAS) with multiple cross-linking networks was developed using chitosan, sodium alginate, polyvinyl alcohol, and glutaraldehyde to adsorb and enrich the anionic dyes form the food samples. The multiple networks in CAS refer to the electrostatic cross-linking network, hydrogen bonding cross-linking network, and covalent cross-linking network. Compared with pure chitosan and alginate sponges, the CAS showed better three-dimensional network structure, mechanical behavior, and stability, which is benefit by multiple cross-linking networks. The physical and chemical properties of CAS were systematically studied by a series of characterizations. The adsorption performance of CAS on anionic dyes was inspected with different dye concentration, time, temperature, and pH conditions. CAS exhibited a good and stable adsorption property to amaranth, carmine, and sunset yellow with the saturation adsorption capacity of 94.34, 111.5, and 80.05 mg center dot g-1, respectively. Furthermore, CAS performed outstanding selectivity to anionic dyes with the selectivity factor up to 16.99. Through electrostatic potential analysis, it is inferred that CAS mainly adsorbs anionic dyes through electrostatic interactions. CAS showed satisfactory reusability, maintaining 97 %-99 % of adsorption performance after six cycles of recycling. Finally, CAS was combined with high-performance liquid chromatography for the enrichment and detection of anionic dyes in candy and cocktail samples, achieving the enrichment factor up to 84.77.

Automated summary

A chitosan-alginate sponge with multiple cross-linking networks was developed for adsorption and enrichment of anionic dyes from food samples. The sponge showed better three-dimensional network structure, mechanical behavior, and stability compared to pure chitosan and alginate sponges. The adsorption performance and selectivity of the sponge were systematically studied, and it maintained high adsorption capacity and selectivity for anionic dyes. The sponge also showed satisfactory reusability and was successfully combined with high-performance liquid chromatography for the enrichment and detection of anionic dyes in candy and cocktail samples.