Mn掺杂赤铁矿的微观结构、表面性质及Se吸附特性研究

Study on Microstructure,Surface Properties and Se Adsorption Properties of Mn Doped Hematite

为研究Mn掺杂赤铁矿(hematite,Hem)的微观结构、表面性质及其对Se(Ⅳ)的吸附特性,制备了Hem和不同比例的Mn掺杂Hem(H-Mn_(x),x=0.1,0.2,0.3)。采用X-射线衍射(X-ray diffraction,XRD)、透射电子显微镜(transmission electron microscop,TEM)、粒径分布、Zeta电位分析和N_(2)等温吸附-脱附实验等方法进行研究。结果表明:Mn掺杂可抑制Hem的晶体形成;随着Mn掺杂比例的升高,H-Mn_(x)的结晶度逐渐减弱、颗粒尺寸不断变小;Hem和H-Mn_(x)对Se(Ⅳ)的等温吸附及动力学吸附过程可分别采用Langmuir模型(R^(2)=0.9499~0.9986)及准二级动力学模型(R^(2)=0.9924~0.9990)进行描述;随着Mn掺杂比例的升高,H-Mn_(x)对Se(Ⅳ)的吸附容量逐渐增加、吸附平衡时间逐渐延长。该研究有助于深入了解土壤中铁氧化物与Se的相互作用,可为土壤中Se的形态调控和高效利用提供理论基础。

In order to study the microstructure,surface properties of Mn doped hematite(Hem),and its adsorption characteristics of Se(Ⅳ),Hem and Mn doped Hem in different proportions(H-Mn_(x),x=0.1,0.2,0.3)were prepared.The samples were investigated by X-ray diffraction(XRD),transmission electron microscop(TEM),particle size distribution,Zeta potential analysis,and N_(2) isothermal adsorption-desorption experiment.The results showed that the crystal formation of Hem could be inhibited by Mn-doping.With increasing the Mn-doping ratio,the crystallinity and particle size of H-Mn_(x) decreased gradually.Langmuir model(R 2=0.9499~0.9986)and quasi-second-order kinetic model(R^(2)=0.9924~0.9990)were used to describe the isothermal adsorption and kinetic adsorption processes of Se(IV)by Hem and H-Mn_(x) respectively.With the increase of Mn-doping ratio,the adsorption capacity of H-Mn_(x) for Se(Ⅳ)increased and the adsorption equilibrium time prolongated.The study helped to understand the interaction between iron oxides and Se in soil,and provided scientific basis for the morphological regulation and efficient utilization of Se in soil.