摘要
采用Box-Behnken响应面分析法对改性粉煤灰去除水中磺胺的影响因素(初始pH值、温度、吸附剂用量)进行优化,建立影响因素与磺胺去除率之间的二次多项式预测模型,并进行热力学分析。结果表明,改性粉煤灰吸附磺胺的最佳条件为:初始pH值2.53、温度35.1℃及吸附剂用量1.76 g/L,在此优化条件下,磺胺的去除率可达78.63%,模型预测值为80.26%,实际值与模型预测值仅偏差1.63%;用Langmuir和Freundlich方程对吸附等温线进行拟合,Langmuir方程拟合结果更好,其最大吸附量为4.1 mg/g,表明改性粉煤灰对磺胺的吸附属于单分子层吸附;改性粉煤灰吸附水中磺胺抗生素的热力学状态函数ΔG、ΔH及ΔS分别为-22.38^-23.89 kJ/mol、7.89 kJ/mol和0.105 kJ/(mol·K),即吸附过程是一个自发、吸热的反应,是熵增加的过程。
The influence factors, including iuifiaI 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 AG, AH and AS 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.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2017年第3期96-101,共6页
Environmental Science & Technology
基金
国家水体污染控制与治理科技重大专项课题(2014ZX07405003)
关键词
改性粉煤灰
吸附
磺胺
响应面法优化
热力学
modified coal fly ash
adsorption
sulfonamide
optimization of response surface method
thermodynamics
