Adsorption of Sulfonamide by Modified Coal Fly Ash: Optimization and Thermodynamics Study
LING Qi
SUN Bingxiang
WU Changnian
HUANG Xianhuai
LI Xia
Abstract：The influence factors,including initial pH,temperature and adsorbent dosage,of the sulfonamide removal by modified coal fly ash were evaluated using Box-Behnken response surface method.A predictive polynomial quadratic equation model was developed,with the subsequent thermodynamic analysis.Results showed that the optimal parameters for sulfonamide adsorption by modified coal fly ash were initial pH of 2.53,temperature of 35.1 ℃ and the adsorbent dosage of 1.76 g/L.Under these optimal conditions,the removal rate of sulfonamide was up to 78.63％,and the predicted value of the model equation was 80.26％,with only 1.63％ deviation for the experimental values.Langmuir and Freundlich were applied to fit the adsorption equilibrium data.Compared with the Freundlich isothermal equations,the Langmuir isotherm adsorption model was found to fit the data better,and the maximal adsorption capacity was 4.1 mg/g.It suggests that the sulfanilamide adsorption by modified fly ash belongs to the monolayer adsorption.Additionally,thermodynamic parameters including △G,△H and △S were calculated with their values of-22.38～-23.89 kJ/mol,7.89 kJ/mol and 0.105 kJ/(mol ·K) respectively,implying the adsorption process is a spontaneous and endothermic reaction,and is the process of entropy increase.
Keywords：modified coal fly ashadsorptionsulfonamideoptimization of response surface methodthermodynamics
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 96-101 )