复合改性膨润土对氨氮废水的吸附及脱附

Adsorption and desorption of ammonia-nitrogen wastewater by modified bentonite

为了研究氨氮的吸附及脱附机理,使用了SDS(十二烷基硫酸钠)和AlCl_3·6H_2O(六水合三氯化铝)复合改性制备的改性膨润土对氨氮废水进行吸附及脱附性能研究。首先通过改性膨润土对含氨氮废水的吸附动力学实验和等温吸附实验研究膨润土的吸附过程,再利用KCl作为脱附剂,对吸附饱和的膨润土进行脱附再生,使用再生的脱附膨润土复合材料进行吸附实验。实验表明,动力学实验中,准二级动力学方程能够更好的模拟氨氮废水的吸附过程,Langmuir模型和Freundlich模型均能拟合氨氮的吸附过程,但综合评价,选用Freundlich等温方程式。脱附剂KCl溶液pH为3、浓度为550 mg·L^(-1)时,搅拌速度为250 r·min^(-1),室温下搅拌20 min,吸附饱和膨润土能够很好地脱附,脱附率达到75.21%。再生的复合膨润土材料对氨氮的去除率为62.83%。

To identify the mechanism of ammonia nitrogen adsorption and desorption,the adsorption / desorption of ammonia nitrogen in wastewater by bentonite modified with a composite of sodium dodecyl sulfate（ SDS） and AlCl3·6H2O（ SDS-Al-B） was investigated. First,the kinetics and isothermal adsorption of ammonia nitrogen by SDS-Al-B was studied. Then,the desorption of saturated bentonite was conducted using KCl as the desorption agent. Finally,adsorption experiments were conducted using the regenerated composite bentonite material. Based on the results of the kinetics experiment,the pseudo-second-order kinetics model can better simulate the adsorption process than the pseudo-first-order kinetics model. In the adsorption isotherm experiment,the Langmuir model and Freundlich model provide good fittings,but a comprehensive evaluation reveals that the Freundlich model is better. For a 550 mg·L^-1 KCl solution at pH 3 and stirring at 250 r·min^-1 for 20 min at room temperature,a very high desorption level（ 75. 21%） was observed. The removal rate of ammonia nitrogen was 62. 83% when using the regenerated composite bentonite materials.