Removal of dyes using multifunctional copolymer comprising, starch-citric, cinnamic, and acrylic acids as an...

A novel adsorbent for removing organic contaminants from wastewater was synthesized via graft copolymerization and cross-linking of starch-based biopolymers. The resulting multifunctional CASCA copolymer, derived from citric acid-modified starch with cinnamic acid and acrylic acid, was investigated using XRD, TGA, SEM-EDX, FT-IR, and BET techniques. Structural characterization confirmed a porous, heterogeneous, and thermally stable framework, which enhanced its adsorption performance toward cationic dyes. The adsorption performance of methylene blue (MB) and crystal violet (CV) was systematically investigated under different pH values, contact times, and initial dye concentrations. The adsorption mechanism followed the pseudo-second-order kinetic model and was effectively fitted by the Sips isotherm model. The maximum adsorption capacities were 564.67 mg/g for MB and 440.22 mg/g for CV. In addition, the CASCA polymer maintained high regeneration efficiency over five successive adsorption and desorption cycles, demonstrating excellent durability and recyclability. Overall, the results demonstrate that the CASCA grafted and cross-linked copolymer derived from starch-rich biomass is an efficient adsorbent for dye removal from wastewater.