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KMID : 1024520170260060719
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Journal of the Environmental Sciences
2017 Volume.26 No. 6 p.719 ~ p.728
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Adsorption Characteristics of Sr Ions by Coal Fly Ash-Based-Zeolite X using Response Surface Modeling Approach
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Lee Chang-Han
Kam Sang-Kyu
Lee Min-Gyu
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Abstract
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In order to investigate the adsorption characteristics for Sr ion using the Na-X zeolite synthesized from coal fly ash, batch tests and response surface analyses were carried out. The adsorption kinetic data for Sr ions, using Na-X zeolite, fitted well with the pseudo-second-order model. The uptake of Sr ions followed the Langmuir isotherm model, with a maximum adsorption capacity of 196.46 mg/g. Thermodynamic studies were conducted at different reaction temperatures, with the results indicating that Sr ion adsorption by Na-X zeolite was an endothermic (ΔHo>0) and spontaneous (ΔGo<0) process. Using the response surface methodology of the Box-Behnken method, initial Sr ion concentration (X1), initial temperature (X2), and initial pH (X3) were selected as the independent variables, while the adsorption of Sr ions by Na-X zeolite was selected as the dependent variable. The experimental data fitted well with a second-order polynomial equation by multiple regression analysis. The value of the determination coefficient (R2=0.9937) and the adjusted determination coefficient (adjusted R2=0.9823) was close to 1, indicating high significance of the model. Statistical results showed the order of Sr removal based on experimental factors to be initial pH > initial concentration > temperature.
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KEYWORD
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Adsorption, Zeolite, Strontium, Fly ash, Box-Behnken method, Response surface modeling
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