Adsorbents for removal of cationic dye: nanocellulose reinforced biopolymer composites

Reusable and eco-friendly poly(vinyl alcohol)/chitin/nanocellulose based biopolymer composite films were synthesized and characterized. Maleic acid (MA) was used as a crosslinker of the biopolymer composite film. The effect of constituent materials of the biopolymer composite film and the pH on removal of methylene blue (MB) dye from aqueous testing solution were studied by batch adsorption studies. The successful deposition of MB dye onto the adsorbent (biopolymer composite film) was confirmed using Fourier transform infrared spectroscopy (FTIR) analysis. Adsorption isotherm studies were fitted to the Freundlich model with the maximum adsorption capacity amounted to 467.5 mg/g. The adsorption kinetics were in conformance to the pseudo-second order model (R-2 = 0.9924-0.9987). The point zero charge (pH(pzc)) of the adsorbents were investigated by pH drift method where the MA cross-linked adsorbents showed pH(pzc) values in the range of 8.05-8.55. Moreover, the best adsorption performance was observed in sample PVA/CT10/NCC/MA30, with calculated maximum adsorption capacity amounted to 467.5 mg/g. Thermodynamic studies showed that the adsorption were spontaneous, exothermic and less-ordered reactions. High adsorption reusability was determined for PVA/CT10/NCC/MA30 composite, with adsorption percentage of 83.67 +/- 1.08% at the fifth cycle. All these positive results implied the potential application of PVA/Chitin/NCC composites for the MB dye's adsorption from aqueous testing solution.