Based on the swelling action of organic solvents on hollow-fiber membranes, a new technique of solvent-swelling and dry-shaping for preparing coiled hollow fibers from straight hollow fibers was introduced. The mass transfer performance of these coiled fibers was tested with 30% TBP (in kerosene)-phenol-water as a working system in a membrane extraction process, and compared with the results obtained from the straight fibers. After long time test, it was proved that the coiled fibers were stable when they contacted with the organic solvent in the membrane extraction process. As to the mass transfer performance, it was found that the presence of vortices in the coiled fibers provided better mass transfer performance than the straight fibers. The improvement factor was in the range of 2–4.With an increase of the phase velocity inside the tube, the mass transfer coefficient and energy input in the coiled fibers grew up much more quickly than that in the straight fibers. An empirical correlation for predicting the mass transfer coefficients and an equation for pressure drop in the coiled fibers were suggested.

The residence time distribution (RTD) curves were measured to observe the shell-side flow status in hollow fiber modules (HFMs) with different packing densities, and with 30%TBP in kerosene/phenol/water as experimental system, the membrane extraction was carried out in three polypropylene HFMs in counter-current flow. A random distribution model described by the Voronoi tessellation method based on normal distribution function was proposed to determine the effect of random packing on the flowstatus and mass transfer characteristics. The standard deviation in normal distribution function represented the packing irregularity in commercial HFMs. So the random distribution model related the packing irregularity with the flow status and mass transfer performance in random packing modules. The theoretical calculation and experimental results indicated that the random packing of fibers caused the non-ideal flow and significant decrease in mass transfer performance; furthermore, the non-ideal flow in shell side had an influence not only on the mass transfer performance in shell side but also on that in lumen side.

Our previous work clearly showed that electro-eletrodialysis was an efficient way to concentrate a formic acid solution. Electro-electrodialysis can be easily scaIed up as electrodialysis, but the equipment cost is higher. Accordingly, an electrolysis process with a new cation-exchange membrane was tested in this work. The effects of concentration, electric current density, and concentration difference between the concentrated side and the dilute side were studied. The experimental results indicated that electrodialysis was also an effective method to concentrate formic acid solution. For the high concentration system the overall current efficiency was larger than 100%. The overall current efficiency for a low concentration system would be up to 90%. But the concentrated ratio is not as much as desired, which is limited by the operating system and conditions. In general, the overall current efficiency was increased to a maximum value with an increase ofthe current density. ARer a certain value, the overall current efficiency would begin to drop. The increase ofthe initial concentration helped to increase the overall current efficiency, but led to a decrease in the concentrated ratio. The volume change of the concentrated solution is seriously affected by the current density and the ratio of the initial concentration in the concentrated compartment compared to that in the dilute compartment.

In this paper, we develop an xpression of Fick's law to be used in the diffusion-solution model when coupling exists. To derive this relationship we have manipulated the generalised Stefan-Mawell equation to get a more convenient generalised multicomponent Fick's law in which clearly defined diffusivities and coupling coefficients appear: the two equations are wholly equivalent. In the general accepted frame of hypotheses when using the solution-diffusion model we have written Fick's equation when coupling betwwen the fluxes exists. The order of magnitude of coupling is calculated, using previously published xperimental data, leading to the conclusion that coupling, in selective pervaporation process, can be neglected.

Two-phase electrophoresis, coupling traditional solvent extraction with electrophoresis, is a novel separation technique. Being bio-compatible, aqueous two-phase electrophoresis provides a successful method for separating mixtures of biomolecules. In this work, the separation of amino acids by aqueous two-phase electrophoresis was examined with dextran-polyethylene glycol-water as a working system. The influences of separation time, field strength, initial solute concentration and two-phase contact area were studied in intermittent separation equipment. The experiment results show that aqueous two-phase electrophoresis is an effective separation technique for amino acids. With time, field strength, and contact area increasing, mass fluxes across the interface are increased quickly.