超重力法制备高分散性镁铝水滑石及其对铀酰离子的吸附性能

Preparation of Highly Dispersed Fine Mg-Al-LDHs by Super-gravity Rotating Bed and Its Adsorption Performance for Uranyl Ions

以硝酸镁(Mg(NO_(3))_(2)·6H_(2)O)和硝酸铝(Al(NO_(3))_(3)·9H_(2)O)为原料、尿素(CO(NH_(2))_(2))为沉淀剂,利用超重力法制备了粒径分布均匀、高分散的片状微细镁铝水滑石。通过扫描电镜、X射线衍射仪及激光粒度分布仪对样品进行了分析表征,比较了传统水热合成法与超重力法制备镁铝水滑石的形貌和粒径分布,分析了镁铝水滑石微细颗粒间形成团聚的机理,考察了异丁醇共沸蒸馏干燥工艺对产品分散性的影响,并研究了制备的镁铝水滑石(Mg-Al-LDHs)对铀酰离子(UO_(2)^(2+))的吸附性能。结果表明,利用超重力法制备的微细Mg-Al-LDHs粒径分布均匀,为六方片状,粒径在1~2.5μm之间;使用非均相共沸蒸馏方法进行干燥,可有效防止Mg-Al-LDHs粉体团聚。在吸附时间120 min、UO_(2)^(2+)初始浓度35 mg/L、吸附剂投加量0.01 g(废水体积30 mL)、pH=6、吸附温度50℃条件下,Mg-Al-LDHs对UO_(2)^(2+)的饱和吸附量为118.57 mg/g。表明Mg-Al-LDHs对UO_(2)^(2+)具有良好的吸附性能,是处理含铀废水的一种潜在吸附剂。

With Mg(NO_(3))_(2)·6H_(2)O and Al(NO_(3))_(3)·9H_(2)O as raw materials,CO(NH_(2))_(2) as a precipitating agent,a kind of flake-like fine Mg-Al-LDHs with uniform particle size distribution and high dispersion was prepared by using super-gravity rotating bed.The samples were analyzed and characterized by SEM,XRD and laser particle size analyzer.The morphology and particle size distribution of the Mg-Al-LDHs prepared by traditional hydrothermal synthesis and super-gravity method were compared.The mechanism of aggregation between fine particles of Mg-Al-LDHs was analyzed and the effect of isobutene azeotropic distillation and drying process on the dispersion of the products was investigated.Also,the adsorption performance of uranyl ions(UO_(2)^(2+))on the prepared Mg-Al-LDHs was studied.Results show the fine Mg-Al-LDHs,being hexagonal and in a flake-like form,has a uniform particle size distribution,with the particle size between 1~2.5μm.The agglomeration of fine Mg-Al-LDHs particles can be effectively prevented by heterogeneous azeotropic distillation and drying process.Under the following condition,including an adsorption time of 120 min,an initial concentration of UO_(2)^(2+)at 35 mg/L,an addition of adsorbent 0.01 g(the volume of wastewater 30 mL),pH of 6,adsorption temperature at 50℃,the saturated adsorption capacity of uranyl ions by Mg-Al-LDHs is 118.57 mg/g.It is shown that Mg-Al-LDHs,due to its good adsorption performance for uranyl ions,is a potential adsorbent for the treatment of uranium-containing wastewater.