Paper-like composites of cellulose acetate-organo-montmorillonite for removal of hazardous anionic dye in water

The shaped solid composites of biopolymers and clay minerals have great potential in the efficient removal of hazardous pollutants from wastewater. Here novel paper-like cellulose acetate/organo-montmorillonite (CA/OMMT) composites were prepared from cellulose acetate (CA) and organo-montmorillonite (OMMT). CA and OMMT were dispersed in acetone, followed by evaporation and drying, thereby leading to paper-like solid CA/OMMT composites. The resulting composite samples were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal gravimetric analyses. The adsorption of Acid Scarlet G (ASG) anionic dye in aqueous solution onto the CA/OMMT composites was tested by varying the pH value of the dye solution, the temperature and time, and the initial dye concentration. The organic modification of montmorillonite facilitated the intercalation of the motifs of CA molecules into the interlayer space of OMMT. There was the intermolecular and intramolecular linkage among CA molecules and OMMT platelets. Dependent on the ratio of CA to OMMT, the composites had a dense or a macroporous paper-like structure. The adsorption capacity of the composites increased with the decrease of the ratio of CA to OMMT and the pH value of the dye solution. The adsorption rate was enhanced with the increase of the temperature. The adsorption was a kinetically controlled, spontaneous and endothermic process. The Lagergren's first-order equation was found to be suited for the adsorption kinetics of ASG onto the CA/OMMT composite. The adsorption isotherm of ASG onto CA/OMMT composites fitted into the Langmuir equation. (C) 2012 Elsevier B.V. All rights reserved.