MFI型沸石吸附分离水体中混合硝基氯苯的研究

Study on adsorption and separation of chloronitrobenzene mixtures in aqueous phase using MFI-type zeolite

采用MFI型沸石(HZSM 5与Silicalite -1沸石)为吸附剂分别吸附水体中的对硝基氯苯和邻硝基氯苯,研究了温度与沸石的结构特性对硝基氯苯吸附的影响,以及2种硝基氯苯分子在MFI型沸石中的扩散行为.结果表明,在不同温度下,对硝基氯苯与邻硝基氯苯在HZSM -5与Silicalite -1沸石中的吸附行为明显不同;对硝基氯苯在2种MFI型沸石中的扩散系数都显著高于邻硝基氯苯.对硝基氯苯与邻硝基氯苯在吸附量与扩散性上的差异导致HZSM- 5与Silicalite- 1沸石对对硝基氯苯的吸附具有良好的选择性.尤其HZSM- 5沸石在低温下更有利于从水体中选择性吸附分离混合硝基氯苯.

The adsorption of p-chloronitrobenzene (p-CNB) and o-chloronitrobenzene (o-CNB) in the wastewater was investigated using MFI-type zeolites (HZSM-5 and Silicalite-1 zeolites) as the adsorbents. The influences of the properties of zeolite and the adsorption temperature on the adsorption of CNBs were studied. Meanwhile, the diffusivities of p-CNB and o-CNB in HZSM-5 and Silicalite-1 zeolites were examined. It was found the adsorption behaviors of p-CNB in HZSM-5 and Silicalite-1 zeolites were markedly different from those of o-CNB, and the diffusion coefficients of p-CNB in the two zeolites were markedly higher, compared to those of o-CNB at the adsorption temperatures. The remarkable difference in the adsorption amounts and diffusivities between p-CNB and o-CNB led to a selective adsorption of p-CNB. Furthermore, a more efficient recovery of p-CNB from the mixture of p- and o-CNB could be achieved in HZSM-5 zeolite at lower adsorption temperature.