Adsorption behavior and antimicrobial activity of sulfonated starch for water purification

New anionic derivative of starch has emerged as promising materials for the adsorption of cationic pollutants. The reaction between tosyl starch and 3-Amino-1-propanesulfonic acid yielded a novel anionic starch derivative functionalized with sulfonic acid groups, denoted as SO₃H@starch. The synthesized derivatives were thoroughly investigated utilizing FT-IR spectroscopy, ¹H NMR spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The SO₃H@starch material exhibited excellent adsorption performance for the removal of methylene blue (MB) with probable reusability. Adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetics, with a maximum adsorption capacity of 270 mg/g. The adsorption process was spontaneous and endothermic, with higher temperatures enhancing the elimination efficiency. The antimicrobial properties of SO₃H@starch were evaluated in vitro against various pathogens by determining their minimum inhibitory concentrations (MIC). The SO₃H@starch derivative exhibited broad-spectrum activity against all tested pathogens, with MIC values as low as 0.037 mg/mL. Notably, E. coli displayed the highest MIC at 0.15 mg/mL, indicating comparatively lower susceptibility. The disinfection effect as well as efficient adsorption capacity of anionic starch derivatives offer a sustainable approach to water purification.