羟基铝柱撑膨润土负载纳米零价铁去除Pb(Ⅱ)

Removal of Pb(Ⅱ) by Al-Pillared Bentonite Supported Nanoscale Zero-Valent Iron

以具有良好吸附性能的羟基铝柱撑膨润土(Al-pillared bentonite,Al-PILC)为载体,通过Na BH_4还原Fe SO_4·7H_2O制得羟基铝柱撑膨润土负载纳米零价铁(NZVI/Al-PILC)。用透射电子显微镜(TEM)和X射线衍射仪(XRD)对NZVI/Al-PILC和纳米零价铁(Nanoscale zero-valent iron,NZVI)进行了表征。将NZVI/Al-PILC和NZVI分别用于合成废水中Pb(Ⅱ)的去除,考察了NZVI/Al-PILC和NZVI与Pb(Ⅱ)反应过程中介质p H、初始Pb(Ⅱ)浓度对其去除率的影响。结果表明:在相同实验条件下,NZVI/Al-PILC对Pb(Ⅱ)的去除率为91.8%,明显优于铁量相同的NZVI对Pb(Ⅱ)的去除率(56.2%),也远高于含铁量相同的NZVI和含土量相同的Al-PILC对Pb(Ⅱ)去除率的加和(70.6%),体现了吸附作用与还原反应之间良好的协同效应。NZVI/Al-PILC和NZVI对Pb(Ⅱ)的反应均符合Langmuir-Hinshelwood动力学方程,且反应速率与NZVI/Al-PILC和NZVI对Pb(Ⅱ)的吸附性能呈正相关。NZVI/Al-PILC呈现出比NZVI更加优异的重复使用性。

Using Al-pillared bentonite as support, nanoscale zero-valent iron（NZVI） supported by Al-pillared bentonite（NZVI/Al-PILC） was prepared by reduction of Fe SO4·7H2O with Na BH4. The structures of NZVI/Al-PILC and NZVI were characterized with transmission electron microscope（TEM） and X-ray diffractometer（XRD）, and the prepared NZVI/Al-PILC composite was used to remove Pb（Ⅱ） in wastewater. The influence of solution p H and initial Pb（Ⅱ） concentration on Pb（Ⅱ） removal was investigated, and the results were compared with that of using NZVI. The results indicate that Pb（Ⅱ） removal efficiency using NZVI/Al-PILC could reach to 91.8%, which is much higher than that of using NZVI（56.2%） with same iron content. It is also higher than the sum of the Pb（Ⅱ） removal efficiency of using NZVI with the same iron amount plus Al-PILC with the same clay amount（70.6%）. Synergetic effects of reduction and sorption exist in the removal of Pb（Ⅱ） with NZVI/Al-PILC. The removal of Pb（Ⅱ） by NZVI/Al-PILC and NZVI can be fitted to the Langmuir-Hinshlwood model, and the reaction rate can be positively related to the adsorption capability. NZVI/Al-PILC has better reusability than that of NZVI.