Cadmium(II) removal from aqueous solution by activated carbon of India shrub wood: Optimization, equilibrium and kinetic modeling

Abstract

Applying easily available, cost-effective and environment friendly adsorbent for removal of pollutants form water has been ongoing research for last decades. The efficiency of new adsorbent that was prepared by India shrub wood for cadmium(II) removal was investigated using response surface methodology (RSM) via Design-Expert (version 7.0.0) software in building an empirical model and statistical analysis, which include the optimization of operating conditions and the study on the interactive effects of experimental factors. The characterization of this new adsorbent carried out using BET, FT-IR, SEM and pH determination at zero point of charge (pH ZPC ). Seventy-eight runs of designed experiments considering the interactive effect of four operative parameters as main variables. The developed quadratic model predicted optimum condition at pH 7, absorbent dose 7 g/L, adsorbate 65 mg/l, and reaction time 50 min that dye removal was 84%. The results showed that all variables solely or in combination with each other seriously affect the removal of cadmium. The fitting experimental data with models disclose the applicability of both isotherm models Langmuir model and Freundlich model for their well presentation and description. Kinetic real rate of adsorption at most conditions efficiently can be represented pseudo-second order.