Efficiency evaluation of zeolite powder, as an adsorbent for the removal of nickel and chromium from aqueous solution: Isotherm and kinetic study

Heavy metals particularly nickel and chromium are recognized as threatening pollutants leaving serious adverse effects on human health and environment due to their toxicity, un-biodegradable properties and high concentration in industrial effluent. The present study aims to evaluate the zeolite powder efficiency, as an adsorbent, in removing nickel and chromium from aqueous solution. After preparing zeolite powder, batch experiments are performed in different times and adsorbent dosages (pH=7, heavy metals concentration=50 mg/L, and stirring/minute= 200rpm).Adsorption isotherm including Langmuir, Freundlich, Pseudo- first order and second-order model, Intra- particle diffusion and Elovich kinetics were applied to correlate the adsorption. Results indicate that nickel absorbs more than chromium and adsorption of both nickel and chromium obeyed the Freundlich model. Correlation coefficients obtained from Freundlich model and pseudo-second order kinetic are R2=0.995, R2=996 and R2=0.999, respectively, which shows that the Freundlich expression and the kinetics of pseudosecond order gave a better fit to the experimental data of zeolite powder. Also, removing Efficiency revealed significant increase after increasing the adsorbent dose and contact time (R2<0.001). According to obtained dimensionless constant separation term (RL) of Langmuir expression, the RL values for the adsorption of both nickel and chromium onto zeolite powder range of 1-0 indicates that the adsorption is a favorable process. © 2016, International Journal of Pharmacy and Technology. All rights reserved