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Process Optimization Study of Zn<sup>2+</sup> Adsorption on Biochar-Alginate Composite Adsorbent by Response Surface Methodology (RSM)

Biswas, Subrata, Bal, Manisha, Behera, Sushanta Kumar, Sen, Tushar Kanti, Meikap, Bhim Charan
Water 2019 v.11 no.2
adsorbents, adsorption, alginates, aqueous solutions, biochar, equations, experimental design, ions, models, response surface methodology, sorption isotherms, temperature, thermodynamics, zinc
A novel biochar alginate composite adsorbent was synthesized and applied for removal of Zn2+ 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 Zn2+ concentration (25&ndash;100 mg/L), adsorbent dose (0.4&ndash;8 g/L) and temperature (298&ndash;318 K) on Zn2+ 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 Zn2+ removal. The optimization study reveals that the initial Zn2+ concentration and adsorbent dose were the most effective parameters for removal of Zn2+ due to higher magnitude of F-statistic value which effects to a large extent of Zn2+ removal. The optimum physicochemical condition for maximum removal of Zn2+ 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 Zn2+ was obtained as 85%.