(255b) Research On Mass Transfer of Metallic Ion Micromass From Phosphoric Acid to Organic Phase by Visualization

Authors: 
Jin-fang, V, C. - Presenter, Hubei Key Lab of Novel Chemical Reactor and Green Chemical Technology
Li-xia, Y. - Presenter, Hubei Key Lab of Novel Chemical Reactor and Green Chemical Technology,Key Laboratory of Green Chemical Process of Ministry of Ed
Ling, L. - Presenter, Wuhan Institute of Technology
Jia, G. - Presenter, Hubei Key Lab of Novel Chemical Reactor and Green Chemical Technology,Key Laboratory of Green Chemical Process of Ministry of Ed


Abstract£º It is difficult for purification of phosphoric acid, and this is a
hot topic in industry. Phosphate rock resources are non-renewable natural
resources. Its use depends on its purity. However, phosphoric acid contains
magnesium, sulfur, chlorine, fluorine, calcium, iron, aluminum and other
impurities which affect its application. In China, some techniques on purification
of phosphoric acid, such as solvent extraction, crystallization, ion exchange,
electrodialysis, precipitation, sulfide precipitation, emulsion liquid membrane
were developed. In 2002, our research group proposed emulsion liquid membrane to
purify phosphoric acid which is an economical and feasible method. But an
industrial scale application was not realized, due to lack of basical experimental
data. In order to speed up the industrialization process, it is necessary to study
on the mass-trasfer behaviors of metallic ions or metallic ion micromasses in
liquid-liquid phase.

In our experiments, the mass-trasfer
behaviors of metallic ion micromasses from phosphoric acid to organic phase
were observed by in a CCD device with visualization technique and visible
light-ultraviolet light. Experimental devices consist of an optical microscope,
a long-distance lense, a miniature reactor, a camera, a video capture card, and
the software for auto tracking image. Combined with infrared spectroscopy and visualization
technology, the mass transfer of metallic ion micromasses in phosphoric acid were
studied from the perspective of submicroscopic. Initially, the density and
viscosity of phosphoric acid solution were measured. The organics were added carefully
to phosphoric acid solution in the miniature reactor. Metallic ion micromasses in the phosphoric acid were moved
upward to the organic phase in 3-5 min. It was observed that the mairomasses
were of level movement and revolving movement. The images captured by CCD were
analyzed to obtain the moving velocity of mairomasses using the software for auto
tracking image.
Application of equation Navier-Stokes, the mechanics of metallic ion mairomasses
in phosphoric acid were analyzed. By setting the appropriate boundary conditions,
the velocity distribution of metallic ion mairomasses in phosphoric acid were
found as follows:

 

By calculation, the fluid
pressure that acting on the surface of micro-particles was 0.2067V0a, and the shear stress that acting on the surface of micro-particles was 0.413V0a. The velocity and geometric diameter of metallic ion mairomasses in phosphoric acid were measured by particle velocity measurement
software. According to the above equation, the theoritical velocity of metallic
ion mairomasses were also calculated, and the result show that the calculated values
agreed with the measured data very well. It explained that this equation is capable of simulating mciromass
transfer. These data can provide a fundamental for emulsion liquid membrane to
purify phosphoric acid.

Key word£ºphosphoric acid purification; emulsion liquid membrane;
visualization; metallic ion micromass; N-S equation

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