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,...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。展开更多
Mesoporous La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SE...Mesoporous La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SEM, AFM, BET, and XPS and the catalytic activity was tested for CO oxidation. The wide-angle XRD patterns showed that La0.8Sr0.2MnO3＋σ perovskite was formed. The SEM and AFM analyses exhibited that La0.8Sr0.2MnO3＋σ by hard-templating method had much smaller particle size（18 nm） than that（40 nm） by the sol-gel method. The perovskite-type oxides La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） also displayed a higher BET surface area from 70 to 143.7 m^2/g and a disordered mesostructure from nitrogen sorption analysis, as well as a small-angle XRD pattern. Moreover, the La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite exhibited a much higher activity in CO oxidation than the conventional La0.8Sr0.2MnO3＋σ perovskite. Further analysis by the means of XPS techniques indicated that the existence of high content of Oads/Olatt species contributed to the high activity.展开更多
文摘为研究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。
文摘Mesoporous La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SEM, AFM, BET, and XPS and the catalytic activity was tested for CO oxidation. The wide-angle XRD patterns showed that La0.8Sr0.2MnO3＋σ perovskite was formed. The SEM and AFM analyses exhibited that La0.8Sr0.2MnO3＋σ by hard-templating method had much smaller particle size（18 nm） than that（40 nm） by the sol-gel method. The perovskite-type oxides La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） also displayed a higher BET surface area from 70 to 143.7 m^2/g and a disordered mesostructure from nitrogen sorption analysis, as well as a small-angle XRD pattern. Moreover, the La0.8Sr0.2MnO3＋σ/z SBA-15（z = 1, 2, 4） perovskite exhibited a much higher activity in CO oxidation than the conventional La0.8Sr0.2MnO3＋σ perovskite. Further analysis by the means of XPS techniques indicated that the existence of high content of Oads/Olatt species contributed to the high activity.
