Mechanistic and adsorption kinetics study of sulfonated activated carbon enhanced starch-based aerogel for high...

Starch-based aerogels, with their low density, high porosity, and high specific surface area, show potential for application in dye adsorption. However, most of the current starch-based aerogels exhibited limitations, such as limited adsorption capacity and poor ability to selective treatment in complex dye wastewater. In this study, acrylic acid (AA) and allyl sulfonic acid sodium salt (AS) were grafted onto the carboxymethyl starch sodium (CMS) backbone via UV-induced radical polymerization, and combined with sulfonated activated carbon (SAC) to prepare a CAA/SAC starch-based aerogel with low density (0.29 g/cm³), high porosity (86.48 %), and notable swelling capacity (60.78 g/g). Activated carbon with porous structures was sulfonated with concentrated sulfuric acid to introduce -SO₃H groups. These groups, along with the negative charges on CMS, AA, and AS, enable selective adsorption of cationic dyes. The adsorption capacity of CAA/SAC aerogel for the cationic dye methylene blue was 136.43 mg/g, which was significantly higher than that of the anionic dye methyl orange (69.31 mg/g). The adsorption process followed both pseudo-second-order kinetics and Langmuir isotherm. The CAA/SAC aerogel can effectively remove dye molecules from wastewater, showing promising potential for various wastewater treatment applications.