EFFECT OF SINGLE-WALLED CARBON NANOTUBES ON THE ADSORPTION OF BASIC RED 12 DYE BY TRIMELLITIC ANHYDRIDE ISOTHIOCYANATE-CROSSLINKED CHITOSAN HYDROGEL

A chitosan hydrogel crosslinked with the least amount of trimellitic anhydride isothiocyanate (H-1) and filled with 0.6 wt% of single-walled carbon nanotubes (SWCNTs) (H-1/SWCNTs) was synthesized. Its structure was proven via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The adsorption capacity of H-1/SWCNTs for Basic red 12 (BR 12) dye, at pH 7 and 25 degrees C, was 14.80 mg g(-1) with a percent removal efficiency of 37.66%, which was greater by 1.8 times than that of the parent hydrogel H-1 (8.21 mg g(-1) and 20.90%, respectively). Its sorption capacity slightly enhanced with decreasing adsorption solution pH. The optimum adsorption capacity of 15.62 mg g(-1) and the % removal efficiency of 39.76% were observed at pH 10 and 25 degrees C. The adsorption of BR 12 dye onto H-1/SWCNTs at different temperatures and different dye solution pH values fitted to the pseudo-second order and the intraparticle diffusion kinetic models. The adsorption isotherm for BR 12 dye by H-1/SWCNTs fitted to the Langmuir isotherm model, indicating the monolayer nature of adsorption. BR 12 dye adsorption onto H-1/SWCNTs is an exothermic process. Thus, the inclusion of SWCNTs into the matrices of functionalized chitosan hydrogel H1 improved its features. It is a suitable way to obtain a favorable composite with high-performance adsorbing characteristic for cationic dyes removal.