X射线衍射-红外光谱-扫描电镜表征超声辅助合成GdPO4：Ce：Tb纳米材料形貌及光学性质

Progresses on the Interaction between Selenium and Mercury in an Aquatic Ecosystem

超声辅助方法是制备纳米材料的有效手段,可提高纳米材料的磁学、光学等特殊性能。本文在不同pH条件下超声辅助合成GdPO4：Ce：Tb三元体系荧光粉,采用X射线粉末衍射、傅里叶变换红外光谱、扫描电镜、透射电子显微镜及光致发光荧光光谱分析方法对样品进行了表征。结果表明：1样品仅在pH=1时,才能生成规则的15nm×104nm六方晶系纳米棒状正磷酸盐绿色荧光粉,晶体优先选择（102）及（200）晶面生长;pH〈1无法得到样品;pH〉1为颗粒状的正磷酸盐绿色荧光粉。2Gd、Ce、Tb三元体系中Ce3＋离子能量较高的5d组态将能量传递给Gd3＋离子,而Gd3＋离子的跃迁发射与Tb3＋离子的吸收峰有较大的光谱重叠,故传递途经是Ce3＋→Gd3＋→Tb3＋;少量Ce3＋的引入可提高以GdPO4基质发光材料的发光强度,此为开发稀土材料提供了理论指导。

Methylmercury is the most toxic form among mercury compounds in the aquatic ecosystem, and poses health risks to organisms through the food chain. The effective control of methylation processes of mercury is an active research field in environmental chemistry and toxicology. Selenium （Se） has a significant suppression effect on the methylation processes of mercury （Hg）. Therefore, it will be beneficial to the prevention and control of mercury contamination to clarify the speciation characteristic of mercury and the interaction mechanisms between mercury and selenium in the aquatic ecosystem. Mercury toxicity is closely associated with the levels of selenium in organisms, the interaction between Hg and Se are mainly embodied in the formation of insoluble compounds to contribute mercury demethylation or methylmercury directly ruled out by inhibition of biological a selenium related enzyme, which inhibits the toxic effect of mercury. In this paper, the speciation and distribution characteristics of mercury and selenium in the aquatic ecosystem and their interaction mechanisms were reviewed. Meanwhile, the reasonable addition of selenium compounds into water will be an effective way to inhibit the methylation processes of mercury in organisms. The development direction for the studies of interaction mechanisms between mercury and selenium and its physical effects in organisms were also reviewed.