Removal of crystal violet dye by adsorption using bentonite - alginate composite

The microwave rapid heating method was successfully applied to the production of bentonite - alginate composite which is effectively used as a sorbent for dye removal. The irradiation method has been proven to assist effectively in the formation of sorbent pores that facilitate the permeation of dye solution. Three nanocomposite models were prepared by varied the mass of bentonite to a certain mass of sodium alginate. In this study, the adsorption performance of bentonite - alginate nanocomposites were tested for the removal of crystal violet dye. The characterizations of the composites were conducted using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and nitrogen sorption methods The adsorption experiments were carried out in batch mode at three different temperatures (30, 50, and 70 degrees C). The adsorption equilibria data were fitted by Langmuir and Freundlich isotherms. The nonlinear fitting coefficient R-2 indicates that the adsorption follows both the isotherm models well. The best adsorption capacity is showed by the composite prepared with the highest proportion of bentonite mass. The high-temperature promotes the adsorption capacity of the composite, where at 70 degrees C the adsorption capacity is reached 601.9339 mg/g (Langmuir parameter, q(max)) or 36.3399 (mg/g)(L/mg)(-n) (Freundlich parameter, K-F). The adsorption kinetic results follow the pseudo-second-order model better than the pseudo-first-order which indicated by higher R-2 values (0.9209 to 0.9916). As indicated by the thermodynamic properties, the adsorption process is controlled by chemisorption.