Dye pollution in water poses serious health and ecological risks, requiring wastewater treatment before discharge and prompting increased research attention due to the widespread use of dyes in various industries. This study investigates the biosorption of methylene blue (MB) using a novel composite of chitosan and Bacillus subtilis exopolysaccharides (EPS). Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the presence of essential functional groups for dye adsorption. The biosorption process was pH-dependent, with optimal removal efficiencies at pH 6 for the chitosan/EPS composite and pH 7 for chitosan alone, showing increased adsorption capacity with rising pH from 3.0 to 7.0. Contact time experiments demonstrated efficient MB removal in approximately 30 min, achieving decolorization rates of 71.6% for the composite and 60.62% for chitosan. The composite also demonstrated a higher …