Experimental Investigation and Modeling of Nickel Removal from Wastewater Using Modified Rice Husk in Continuous Reactor by Response Surface Methodology

Abstract

In this paper, we investigate the adsorption efficiency of modified rice husk for continuous removal of Ni(II) ions by evaluating the breakthrough curves obtained at different bed heights, initial Ni(II) concentrations, and flow rates. We use response surface methodology to investigate the individual as well as cumulative effect of these process variables optimizing the process conditions for the maximum removal of Ni(II) from aqueous solution. We statistically evaluate our obtained quadratic model through analysis of variance, student’s t test, and residual test. According to our results, height of adsorbent is the most effective parameter on continuous Ni(II) removal efficiency with a positive effect, while initial Ni(II) concentration has negative effect on adsorption efficiency, and flow rate is negligible. Our predicted values of Ni(II) removal obtained by using the response functions match perfectly with our experimental data. Under the optimum condition, the removal efficiency of Ni(II) ions is 63.57%. According to our batch experiments, the adsorption process can be well described by both Langmuir and Freundlich equilibrium isotherm models resulting in a maximum adsorption capacity for Ni(II) ions by modified rice husk as 26.6 mg/g.