Starch-grafted-poly(acrylic acid)/Pterocladia capillacea–derived activated carbon composite for removal of methylene blue dye from water

Abstract

AbstractStarch-g-poly(acrylic acid)/Pterocladia capillacea–derived activated carbon (St-g-P(AA)/P-AC) composites were prepared via aqueous solution graft copolymerization using starch, acrylic acid, and activated carbon of red alga Pterocladia capillacea (0–10%) with N,N′-methylenebisacrylamide crosslinker and ammonium persulfate (NH4)2S2O8 initiator. Fourier-transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize St-g-P(AA)/P-AC composites. Additionally, St-g-P(AA)/P-AC composites were investigated for methylene blue (MB) dye removal from water. The impact of the beginning concentration of MB dye, temperature, pH, and adsorption time on MB dye removal was examined. The maximum adsorption capacity obtained at pH 8 was 496.29 mg/g at 0.02 mg/L composites dose and 100 mg/L MB dye. The properties of adsorption were studied by the adsorption isotherm, kinetic, and thermodynamic models. The pseudo-first-order and Freundlich isotherm models demonstrated the kinetics and equilibrium adsorptions data, respectively. The maximum monolayer capacity (qm) was 1428.57 mg/g from Langmuir isotherm. Thermodynamic parameters indicated that the MB dye adsorption is exothermic physisorption and spontaneous. The results show that St-g-P(AA)/P-AC composites were effective for MB dye adsorption from water solution and could be recycled.