Synthesis, Characterization, and Evaluation of Cassava Starch Phosphate Carbamates for Chemical Dye Adsorption in Water Remediation

ABSTRACT Cassava starch was modified using urea and ortho‐phosphoric acid to produce cassava starch phosphate carbamate (CSPC) derivatives with enhanced water absorption and dye adsorption properties. Their structural, physicochemical, and functional characteristics were systematically evaluated. Methylene blue (MB) adsorption studies revealed that CSPCs achieved capacities ranging from 19.08 mg/g to 191.67 mg/g at different adsorbent dosages and 49.7 mg/g to 228 mg/g at different initial dye concentration at equilibrium. The adsorption process followed a pseudo‐second‐order kinetic model, and the equilibrium data fitted both Langmuir and Freundlich isotherms, suggesting combined monolayer physisorption, and heterogeneous chemisorption driven by electrostatic interactions. CSPCs also demonstrated reusability, maintaining >96% of initial adsorption capacity after three cycles. These findings highlight cassava starch phosphate carbamates as promising sustainable adsorbents for cationic dye removal in water remediation.