微乳液体系相图的研究及其在纳米氟化物制备中的应用

绘制了十六烷基三甲基溴化铵(CTAB)/正丁醇(n-C4H9OH)/正辛烷(n-C8H18)/水[或NH4F溶液、或Ba(NO3)2溶液、或KNO3-Mg(NO3)2混合溶液]四组分微乳体系的拟三元相图.观察了电导率随水(或盐溶液)含量变化的规律,很好地印证了微乳液体系的相行为.选取相图中微乳区点作为最佳条件,制备了KMgF3纳米粒子.

纳米NaYb_(1-x)F_(4)∶Er^(3+)_(x)中Er^(3+)/Yb^(3+)掺杂浓度变化引起的相变和发光增强

在Yb^(3+)和Er^(3+)共掺杂氟化物纳米体系中,2%Er^(3+)掺杂浓度为上转换发光的最佳浓度,高于这个浓度,随着Er^(3+)掺杂浓度的增加,将发生严重上转换发光浓度猝灭,已为人们广泛认知和接受。本文合成了不同Er^(3+)/Yb^(3+)掺杂浓度比的NaYb_(1-x)F_(4)∶Er^(3+)_(x)系列上转换发光纳米粒子。通过扫描电镜、XRD和荧光光谱等分析方法对这些合成的样品进行了表征。研究结果表明,当Er^(3+)/Yb^(3+)掺杂浓度比在0.02/0.98~0.2/0.8和0.6/0.4~0.8/0.2范围时,合成的NaYb_(1-x)F_(4)∶Er^(3+)_(x)纳米粒子分别为α相和β相结构;而特别值得注意的是,当掺杂浓度比在0.3/0.7~0.4/0.6范围时,合成的纳米粒子为从α相向β相过渡的α相和β相共存相结构。Er^(3+)/Yb^(3+)最佳掺杂浓度比分别为0.02/0.98和0.4/0.6的两种α相和β相共存相结构的纳米粒子都展现了非常好的上转换发光增强。这些结果对于理解稀土离子浓度发光猝灭机制,提高上转换发光效率,促进稀土纳米发光材料在新型光源、生物医学和激光等领域的应用都具有重要的科学研究意义和启发作用。

微乳液法制备BaYF_5:Eu^(2+)纳米粒子及光谱特性研究

采用微乳液法制备了BaYF5:Eu2+纳米微粒,并利用X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光光谱等手段进行了表征。XRD数据与标准卡片PDF#46-39很好吻合,利用谢乐公式计算所制备产物平均粒径在20 nm左右。SEM图谱显示所制备的纳米粒子为球形,且形貌规则,粒径分布比较均匀。BaYF5:Eu2+的发射光谱中存在一个300~410 nm的发射带,发射光谱最强峰为330 nm,对应于Eu2+的4f65d→4f7发射,与传统高温固相法所制多晶材料最强发射峰378 nm相比蓝移了48 nm;其激发光谱最强峰位于263 nm,与传统高温固相法所制多晶材料最强激发峰322 nm相比蓝移了59 nm。

Development of a novel nano-biosorbent for the removal of fluoride from water

The study was designed to investigate the use of two sorbents namely(i) Fe3O4 nanoparticles immobilized in sodium alginate matrix(FNPSA) and(ii) Fe3O4 nanoparticles and saponified orange peel residue immobilized in sodium alginate matrix(FNPSOPR) as sorbents for fluoride removal from contaminated water. The synthesized nanoparticles were analyzed and characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, and scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier transform-infrared spectrometry. The sorbent matrices were prepared in the form of beads and surface functionalized to enable enhanced sorption of fluoride ions. Batch sorption studies were carried out and the sorption isotherm and reaction kinetics were analyzed. Both the sorbents followed Langmuir model of isotherm and fitted well with Pseudo first order reaction. The maximum sorption capacity exhibited by FNPSA and FNPSOPR was58.24 mg·g-1and 80.33 mg·g-1respectively. Five sorption–desorption cycles exhibited 100%, 97.56%, 94.53%,83.21%, and 76.53% of regeneration of FNPSOPR. Accordingly, it is demonstrated that FNSOPR could be used as a promising sorbent for easy and efficient removal of fluoride from contaminated water with good reusability.The current work suggests a simple and effective method to remove fluoride from contaminated water.