Preparation and characterization of cellulose nanocrystals with different aspect ratios as nano-composite membrane for cationic dye removal

Two cellulose nanocrystals (CNCs) with different aspect ratios in dimension derived from raw microcrystalline cellulose were prepared and presented in this paper. The morphological features of nanostructures were explored with TEM. Then the structure analysis, surface charge and thermal degradation behavior of CNCs were characterized and determined by FTIR/X-ray diffraction, zeta potential and TGA, respectively. Furthermore, the hybrid CNCs nano-composite membranes were facilely fabricated via vacuum-dewatered process for effective removal of cationic dyes (up to 99.9% removal of methylene blue at 10 mg/L and 97.9% removal of rhodamine B at 20 mg/L). The mechanism of such effective cationic dye removal is derived from the combined effect of both electrostatic interaction and steric hindrance between the CNC composite membrane and the cationic dyes during the filtration process. In addition, the permeation flux and dye removal efficacy of the composite membrane are CNCs loading-concentration dependent.