Process optimization study of Zn 2+ + adsorption on biochar-alginate composite adsorbent by response surface methodology (RSM)

Abstract

A novel biochar alginate composite adsorbent was synthesized and applied for removal of Zn 2+ + ions from aqueous solution. Kinetics, equilibrium and thermodynamic studies showed the suitability of the adsorbent. From a Langmuir isotherm study, the maximum monolayer adsorption capacity of the composite adsorbent was found to be 120 mg/g. To investigate the effect of process variables like initial Zn 2+ + concentration (25-100 mg/L), adsorbent dose (0.4-8 g/L) and temperature (298-318 K) on Zn 2+ adsorption, response surface methodology (RSM) based on a three independent variables central composite design of experiments was employed. A quadratic model equation was developed to predict the relationship between the independent variables and response for maximum Zn 2+ + removal. The optimization study reveals that the initial Zn 2+ + concentration and adsorbent dose were the most effective parameters for removal of Zn 2+ + due to higher magnitude of F-statistic value which effects to a large extent of Zn 2+ + removal. The optimum physicochemical condition for maximum removal of Zn 2+ + was determined from the RSM study. The optimum conditions are 43.18 mg/L initial metal ion concentration, 0.062 g adsorbent dose and a system temperature of 313.5 K. At this particular condition, the removal efficiency of Zn 2+ + was obtained as 85%.