Kensaku Mizoguchi

PERVAPORATION OF ETHANOL/WATER THROUGH A POLY (VINYL ALCOHOL)/CYCLODEXTRIN(PVA/CD) MEMBRANE

Abstract A poly(vinyl alcohol)/cyclodextrin (PVA/CD) membrane was utilized in the pervaporation of ethanol/water mixtures. The membrane was prepared by casting an aqueous solution of PVA and β-cyclodextrin oligomer. The CD oligomer was successfully immobilized in the membrane by the crosslinking of PVA with glutaraldehyde for 1 h. The content of CD was up to 33%. The effect of CD on the pervaporation performances of water/ethanol was investigated by measurements of the sorption equilibrium and the calculations of the diffusion coefficient of the permeants in the membrane. The addition of CD increased the water selectivity of the pervaporation of water/ethanol, especially at lower (

Pervaporation of benzene/cyclohexane and benzene/n-hexane mixtures through PVA membranes

Poly(vinyl alcohol) (PVA) membranes (both homogeneous and asymmetric) were studied for the pervaporation separation of benzene/n-hexane and benzene/cyclohexane mixtures. The asymmetric PVA membrane with skin and porous layers was prepared through the phase inversion technique. Both asymmetric and homogeneous membranes were benzene-selective for all the feed compositions. The benzene separation factor of homogeneous PVA membrane was smaller than three, and the total permeation flux was several g/m2/h. The benzene selectivity of the asymmetric PVA membrane was much higher than that of the homogeneous membrane; weight fraction of benzene in the permeate side was larger than 90% for all the feed compositions. On the other hand, the total flux was almost unchanged compared with that of the homogeneous membrane. These results indicate that the density of the skin layer of the asymmetric membrane should be much higher than that of the homogeneous membrane.

Ultrafiltration behavior of a new type of non-ionic surfactant around the CMC

The ultrafiltration (UF) behavior of a surfactant with drag reducing properties was investigated. The UF membrane used was a hydrophilic YM-1 (cut-off 1000) polysaccharide (Amicon). The surfactant used was a non-ionic type N-lauryl-N,N-dimethylaminoxide (LDAO). The total permeation fluxes decreased drastically in the special concentration range just below the CMC. The phenomenon was observed even when the applied pressure was changed. It was concluded that the pre-micelles formed dynamically in this concentration range.

Pervaporation membranes for ethanol-water mixture prepared by plasma polymerization of fluorocarbons. II. Perfluoropropane membranes☆

Abstract Pervaporation membranes for ethanol-water binary mixtures were prepared by plasma polymerization of perfluoropropane (PFP). The plasma-polymerized thin films were deposited onto porous polysulfone (PS) filters as substrates with an average pore size from 0.1 to 0.45 μm. By adding argon carrier to PFP system, fluorine/carbon elemental ratios (F/C) of the produced membranes evaluated by X-ray photoelectron spectroscopy (XPS), showed a maximum value, then slightly decreased at higher partial pressure of Ar. This tendency was recognized more clearly by comparing the summation of −CF3 and −CF2-peak area percentages based on a whole C18 peak area. As a measure of hydrophobicity, this value is more intelligible than the direct F/C ratio. The influence of substrate pore-size, plasma-treatment time and hydrophobicity of the membranes on the separation capability were studied. The ethanol-separation coefficient, (αEtOH), of PFP membranes increased slightly with decrease of the average pore-size of the substrates, but treatment time did not apparently affect the αEtOH. We classified the prepared membranes into two classes, i.e. the membranes showing higher and lower permeation fluxes than 0.5 kg/m2-hr. The αEtOH was more evidently observed to increase with membrane hydrophobicity for the former class of PFP membranes. We suggest that, at least, three separation schemes might be necessary to understand the correlations found in each group.

Relationship between permselectivity and permeability in pervaporation of water/alcohol mixture

Abstract The evaporation mechanism of a water/alcohol mixture with a polymeric membrane was investigated. Flory-Huggins thermodynamics was adopted to introduce the selective dissolution factor, R . It was shown that the value of R of a water permselective membrane increases as permeability decreases, and that it has no upper limit. For an ethanol permselective membrane, R has a maximum value at a certain value of the swelling ratio. Making some assumptions for R , a semi-quantitative relationship between permselectivity and permeability, J , was derived for a water permselective membrane and examined experimentally. When the swelling ratio is changed, it can be said that selectivity is proportional to J 1− ( 1 s ) depending on s , the molecular volume ratio of water to alcohol.

Preparation of a cyclophane-bonded stationary phase and its application to separation of naphthalene derivatives

A cyclophane (CP44)-bonded silica gel stationary phase was prepared and elution behaviour of hydrophobic solutes was investigated in the reversed-phase mode. Aromatic compounds were retained on the stationary phases more strongly than the corresponding alicyclic compounds, as was expected by the complex-forming ability of the cyclophane. The stationary phases also showed isomer-selective separation for monomethyl- and dimethylnaphthalenes. The isomers having methyl groups at the α-position were eluted prior to those having methyl groups at the β-position, i.e., the retention order for methylnaphthalene was, α<β and that for dimethylnaphthalene, α,α<α,β<β,β. Moreover, some dimethylnaphthalene isomers which cannot be separated on ordinary reversed-phase stationary phases were separated finely on this stationary phase. The separation mechanism is discussed on the basis of the structure of the cyclophane-involved complex.

Simple thermodynamics of macroscopic phase separation in shrinking gels

The shrinking process induced in spherical gels by an abrupt change in temperature has been investigated qualitatively. The phase diagram of the gel system has been found to be helpful in classifying a variety of shrinking processes. When the solvent quality is lowered within the region between the volume transition and coexistence temperatures, the local swelling ratio of the inner portion, which is divided by a moving interface from the outer shrunk phase, declines in the course of the shrinking process. On the contrary, the local swelling ratio of the inner portion of the shrinking gel is enlarged when the solvent quality is lowered into the region between the coexistence and spinodal temperatures. In this latter case, owing to large local swelling of the inner portion in the vicinity of the interface, spherical symmetry will imply mechanical instability. This instability will be the origin of transient spatial patterns on the surfaces of shrinking gels.

Numerical Investigation of the Limiting Sliding Condition of Polyoxymethylene with Various Sliding Geometry

A numerical simulation code was developed for estimating the surface temperature of POM wear test with different shapes. By using the developed code, the effect of sliding geometry with various contact areas on the surface temperature was numerically investigated. The simulation results show that the limiting sliding velocity depends on contact area and reaches a peak value at a certain geometry. It was also found that the simulation code leads an exact prediction of limiting velocity in the range of small contact area. This is important since the exact temperature measurement is very difficult in this range.

Eco-design of water purification equipment for domestic use

Though a lot of water purification equipments are used in Japan and collected by the suppliers after a sage, they are not adequately recycled or reused due to the high cost of reproduction. We investigated the feasibility of three proposed equipments (cartridge) to construct a new recycling system, considering all through the cost of production and recycling, and environmental load. As a result of analysis, application of polypropylene as main cartridge material was found to be the best one for establishment of fundamental purpose.

A new program for integrated recycle system of chemical products

A working group of the Society of Chemical Engineers of Japan (SCEJ) attempted to propose a new design concept for chemical products by analyzing and investigating chemical industries, recent development of computer science and life cycle assessment method. The keys of the proposed concept are the first to introduce multi-recycle system for the individual chemical product and the second to introduce computer science to design the product from the molecular level, taking into account not only its function but also recycability.