Mg-Al-Me(Me=La,Ce,Zr)复合氧化物制备及其除氟性能  

Preparation of Mg-Al-Me(Me = La,Ce,Zr) Composite Oxides for Efficient Fluoride Uptake

作　　者：汪爱河[1,2] 周康根[1] 刘行[1] 陈泉州 刘芳[1] 

机构地区：[1]中南大学冶金与环境学院,长沙410083 [2]湖南城市学院市政与测绘工程学院,益阳413000

出　　处：《环境科学》2016年第12期4874-4881,共8页Environmental Science

基　　金：国家水体污染控制与治理科技重大专项(2010ZX07212-008)

摘　　要：采用双滴共沉淀-煅烧法制备Mg-Al-Me(Me=La,Ce,Zr)金属复合氧化物吸附剂,通过扫描电子显微镜(SEM)和X射线衍射(XRD)对制备的吸附剂进行表征.采用批实验考察了吸附时间,初始氟浓度和共存离子(Cl^-、NO_3^-、SO_4^(2-)、CO_3^(2-)、HCO_3^-、PO_4^(3-))对氟吸附性能的影响.结果表明,3种吸附剂对氟吸附过程可用准二级动力学模型描述.3种吸附剂对氟吸附速率主要受液膜扩散速率、颗粒内扩散速率和吸附反应速率共同控制.等温吸附结果显示Mg-Al-La对氟吸附能力最大,MgAl-Ce次之,Mg-Al-Zr最小,3种材料对氟吸附规律均符合Langmuir等温吸附方程,其最大饱和吸附量分别为54.22、51.65、50.89 mg·g-1.共存离子对3种材料吸氟存在不同程度的竞争,其影响次序是Cl^-<NO_3^-<SO_4^(2-)<CO_3^(2-)≈HCO_3^-<PO_4^(3-).The Mg-Al-Me（ Me = La,Ce,Zr） composites were prepared by co-precipitation method of Mg,Al,Me（ Me = La,Ce,Zr）salt solutions with a molar ratio of 20∶ 1∶ 4. The sample were calcined at 500℃ for 5h as the adsorbents for removal of fluoride. The adsorbents were characterized by scanning electron microscopy（ SEM） and X-ray diffraction（ XRD）. The patterns of SEM indicated that three calcined sorbents were somewhat agglomerated particles to form a sheet structure after adsorption. The patterns of XRD showed that the three adsorbents fored a metal composite oxide. The effects of adsorption time,initial concentration of fluorine and coexisting ions（ Cl-,NO3^-,SO4^2-,CO3^2-,HCO3^-,PO4^3-） fluorine adsorption properties on three adsorbents were tested by batch adsorption experiments. The results showed that the kinetics of fluorine on three adsorbents were well fitted by pseudo-second-order model. And the adsorption rate of fluoride on three adsorbents decreased in the order of Mg-Al-Zr Mg-Al-La Mg-Al-Ce. Regression results of adsorption rate controlling step test by moving boundary model indicated that intra-particle diffusion rate was not the only ratelimiting step in the adsorption of fluoride on the three materials. The equilibrium isotherm showed that the adsorption capacity of fluoride uptake by three adsorbents decreased in the order of Mg-Al-La Mg-Al-Ce Mg-Al-Zr. The adsorption isotherm of three adsorbents was very well described by the Langmuir models, and their linear correlations were 0. 995 8,0. 979 0,0. 997 5,respectively. The maximum adsorption capacities of fluoride on Mg-Al-La,Mg-Al-Ce,Mg-Al-Zr calculated by Langmuir model were as high as 54. 22,51. 65,50. 89 mg·g- 1,respectively. The results showed that the co-existing anions such as CO3^2-,HCO3^-,PO4^3-had an inhibitory effect on the Mg-Al-La,Mg-Al-Ce,Mg-Al-Zr adsorption of fluoride. The effect of coexisting anions on fluoride adsorption increased in the order of Cl- NO3^- SO4^2- CO3^2-≈HCO3^- PO4^3-.

关 键 词：稀有金属 含氟废水 吸附等温线 吸附动力学 动边界模型 

分 类 号：X131[环境科学与工程—环境科学] X703.1