胡萝卜渣对Cr^(6+)的吸附作用及吸附机理的研究

STUDY ON ADSORPTION AND ADSORPTION MECHANISM OF Cr^(6+) BY CARROT POMACE

研究了胡萝卜渣对Cr6+的吸附作用及吸附过程的影响因素、热力学和动力学行为,结果表明:吸附率随胡萝卜渣粒径的减少而增大;Cr6+初始质量浓度相同时,吸附率随加入胡萝卜渣量的增加而增大,胡萝卜渣加入量相同时,吸附率均出现两次极小值且初始质量浓度为15 mg/L时吸附率最佳;正交试验结果表明:3个因素影响程度依次为温度>pH>时间,最佳吸附条件为溶液pH2、温度60℃、浸泡时间10 h;吸附等温线结果表明:胡萝卜渣对Cr6+的吸附以单分子层吸附占优势,Freundlich吸附等温式吸附热力学行为,吸附为吸热过程,胡萝卜渣对Cr6+的吸附热为53.6 kJ/mol;吸附动力曲线结果表明:二级动力学模型能较好地描述胡萝卜渣对Cr6+的吸附动力学行为.

The paper studied the adsorption of Cr 6＋ by carrot pomace,the influence factors,the thermodynamic and kinetic behaviors of the adsorption process.The results showed that the adsorption rate increased as the particle diameter of the carrot pomace was reduced;the adsorption rate increased with the increase of the amount of the carrot pomace under the condition of same Cr 6＋ initial concentration;the adsorption rate had two minimum values under the condition of same addition amount of carrot pomace,and had the largest value when the Cr 6＋ initial concentration was 15 mg/L.Orthogonal experiments showed that the order of the influence degree of the three factors was temperature,pH and time;and the optimum adsorption conditions were as follows： pH 2.0, temperature 60 ℃ and soaking time 10 hours.The result of adsorption isotherm showed that monolayer adsorption was predominant;the adsorption isotherm fit the thermodynamic behavior of Freundlich adsorption; the adsorption process was the endothermic process;and the adsorptive heat of Cr 6＋ was 53.6 kJ·mol-1.The adsorption kinetic curve showed that the second-order kinetic model could well describe the adsorption kinetic behavior of carrot pomace.