纳米硫酸钡制备过程中的蒸馏法破乳和微孔液的循环使用

以硫酸钠和氯化钡的W／O型微乳液反应制备纳米硫酸钡为实验体系，利用微乳液中各组分沸点的差异，提出了利用蒸馏法破坏微乳液，实现纳米颗粒与微乳液体系的分离以及微乳液循环利用的新工艺。研究了破乳时蒸馏温度、循环使用时体系中的盐浓度、含水量等因素对纳米颗粒品质的影响，比较了蒸馏法破乳和加高浓度盐、升高温度等方法破乳对纳米颗粒回收率的影响。实验结果表明，蒸馏温度升高不会导致纳米颗粒的团聚，随着循环次数的增加，粒径从第一次制备的14nm增加到第五次制备的25nm，但单分散性和分布仍然良好；体系中水含量过大，制备出的纳米颗粒粒径不均一；此外蒸馏法破乳回收纳米颗粒的收率可以达到82％，高于加盐破乳和升温破乳的回收率。

Reuse of Microemulsion for Preparing Barium Sulfate Nanoparticles through Breaking the Microemulsion by Distillation

With water-in-oil (W/O) microemulsion of BaCl2 and Na2SO4 as an experimental system, a distillation method was proposed to separate the formed nanoparticles of BaSO4 from microemulsion systems and in this process the emulsifiers can be reused. The influences of the distillation temperature, rounds of microemulsion recirculation and the water content in the microemulsion on the properties of nanoparticles were investigated. It is found that an increase in the distillation temperature will not lead to particle aggregation; with the increasing of recirculation rounds, the particle size increases to some extent, but it still remains in the range of nanosize and the monodispersion can also be maintained. Higher water content in the microemulsion system results in an non-uniform size of nanoparticles. The nanoparticle recovery efficiency, which may reach as high as 82%, suggestes that distillation is an efficient method for microemulsion breaking, and it is superior to those methods which requires heating the system up or adding high concentration of salt to the system.