Organophilicized Bentonite for Adsorptive Removal of Methylene Blue (MB) Dye in Aqueous Medium: Thermodynamics, Kinetics and Equilibrium Studies

Abstract

HDTMA and TMPA cations intercalated bentonite clay has been assessed for the effective removal of methylene blue dye (MB) in aqueous solution. The adsorbents has been characterized by Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Various sorption parameters like effect of initial MB concentration, contact time and pH were used to investigate the sorption process. Langmuir and Freundlich isotherms as well as Pseudo First order, Pseudo Second order and intraparticle diffusion kinetic models were applied to investigate the sorption mechanisms. Results from the adsorption experiment confirmed 180 minutes as equilibrium time for maximum sorption of MB by both organoclays. Increase in initial MB concentration resulted to a corresponding increase in the adsorption capacities of both organoclays. Adsorption of MB by the organoclays were highly influenced by pH, as maximum sorption of MB was achieved at pH of 7. Among the isotherm and kinetic models exploited, the Langmuir isotherm and Pseudo second order kinetic model gave best fit to the experimental data respectively. Results from thermodynamic studies showed that the process of adsorption of MB onto the organoclays were feasible, spontaneous and exothermic; and successful reapplication of regenerated spent organoclays (Bt-HDTMA and Bt-TMPA) yielded MB dye removal percentage of 89.6 and 85.3% respectively at 60 minutes contact time. Therefore, the results obtained from the entire study confirms the efficacy of HDTMA and TMPA intercalated bentonite clay for effective removal of cationic dyes in aqueous solution at optimal experimental conditions