天然沸石对农田退水中氨氮的去除

Removal of ammonium-nitrogen from irrigation drainage by the natural zeolite

利用静态吸附实验研究了沸石颗粒大小、氨氮初始浓度、接触时间及Na+离子浓度等因素对天然白银沸石去除模拟黄灌区农田退水中氨氮(NH4+-N)效果的影响,同时研究了吸附等温线特征,并考察了其吸附机理.研究结果表明,沸石颗粒大小、接触时间及NH4+和Na+初始浓度对NH4+-N交换容量都会产生一定影响;根据复相关系数(R2),NH4+-N的吸附等温线更符合三参数等温线模型;而对于两参数等温线模型,Langmuir模型比Freundlich模型能更好地描述NH4+-N在天然沸石上的离子交换过程;NH4+-N吸附实验数据与Elovich模型拟合最好(R2≥0.9766).研究结果表明了天然白银沸石是一种适合NH4+-N去除的离子交换剂,可用于黄灌区农田退水中NH4+-N的去除.

Static adsorption experiments were carried out to remove ammonium-nitrogen from the irrigation drainage by the natural zeolite.The effects of zeolite particle size,initial NH＋4-N concentration,contact time and coexistent cations on the removal efficiency were investigated.The adsorption isotherms were obtained and the kinetic data were determined.It was demonstrated that the initial concentrations of NH＋4-N and Na＋ had significant effect on the exchange capacity of NH＋4-N.The adsorption isotherm of NH＋4-N fits the three-parameter isotherm models（Redlich-Peterson and Langmuir-Freundlich） better than the two-parameter isotherm models in terms of the multiple correlation coefficient（R2）.For two-parameter isotherm models,the Langmuir model provides a better description of the ion-exchange process than the Freundlich model.The adsorption data are fitted by the Elovich model best.Based on the present experimental results,it can be concluded that the natural zeolite is a suitable ion exchanger for NH＋4-N removal,and it can be used to remove NH＋4-N from the irrigation drainage.