Removal of methylene blue from aqueous solutions using modified clay

Introduction: Discharging of industrial colored wastewaters especially into aqueous environments can cause adverse effects on aquatic life due to their toxic natures. In this study, montmorillonite modified by hexadecyltrimethyl ammonium bromide (HDTMA-Mt) was used for the adsorption of methylene blue (MB). Materials and Methods: The influence of surfactant loading rate, contact time, pH, adsorbent dosage, adsorbate concentration and ion strength in batch system was evaluated. HDTMA-Mt was also characterized by using Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Results: Fitting the experimental data to different kinetics and isotherm models including pseudo-first order kinetic, pseudo-second order kinetic, Langmuir and Freundlich isotherms showed that the experimental data is well descripted by pseudo-second order kinetic (R2=1) and Freundlich (R2>99) models. The optimum contact time for the sorption was achieved at 60 min and changing in pH values had insignificant effects on the sorption. Conclusion: The findings of the present study indicated that HDTMA-Mt can be successfully applied for the removal of MB from aqueous solutions. The modified Mt, due to high accessibility, low cost and non-toxicity, can be considered to replace with other high cost adsorbents