小麦秸秆生物碳质吸附剂从水中吸附硝基苯的机理

Adsorption Mechanism of Nitrobenzene by Biological Carbon Sorbent Prepared from Wheat Straw in Water

在炭化温度为300℃下,以小麦秸秆为材料制备生物碳质吸附剂,采用批量平衡试验,研究了其对水中硝基苯的吸附特性,并从动力学及热力学角度探讨其吸附硝基苯的作用机理.结果表明,硝基苯在生物碳质上的吸附过程符合拉格朗日假二级动力学方程,反应活化能为12.2 kJ/mol;吸附行为可用Freundlich吸附等温方程描述,饱和吸附容量为91.58 mg/g.由吸附热力学方程计算得到的等量吸附焓变(ΔH)<0,吸附自由能变(ΔG)<0,吸附熵变(ΔS)>0,表明生物碳质对硝基苯的吸附为放热和熵减少的自发过程.

A batch sorption study was carried out to investigate the properties, kinetics and thermodynamics of the sorption process of nitrobenzene onto the biological carbon sorbent prepared by wheat straw at 300 ~C. The results showed that the sorption process followed the pseudo-second order kinetic equation, and the activation energy was 12. 2 kJ/mol. The adsorption behavior fitted well to the Freundlich sorption isotherm equation, and the maximum sorption capacity was 91.58 mg/g. The results of thermodynamic analysis were as follows： enthalpy （AH） 〈 O, Gibbs free energy （AG） 〈 0, and entropy （AS） 〉 O, which suggested that the sorption of nitrobenzene onto the biological carbon sorbent was an exothermic, spontaneous and decreasing entropy process.