Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Patent
1991-03-25
1992-11-17
McCamish, Marion E.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
522118, 522120, 522124, 522149, 210640, C08J 328
Patent
active
051644240
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention concerns new polymers and a process for producing such polymers that are suitable as material for solution diffusion membranes. In another regard this invention concerns the use of such solution diffusion membranes for pervaporation.
Pervaporation is a separation process whereby a liquid to be separated, generally a liquid mixture, is brought in contact with a first or feed side of a suitable membrane. If the vapor partial pressures of the components of the fluid or liquid on the second or permeate side of the membrane are kept at levels lower than the corresponding values on the first side, the result is a driving force for the movement of these components through the membrane. The components pass through the membrane at different rates in accordance with their respective permeabilities where the permeability is dependent in a complex manner on a number of different parameters which include, for example, the type and concentration of the permeating species, the type and structure of the membrane, the composition of the fluid or liquid, the temperature, etc. Since the vapor partial pressures on the second side of the membrane are lower than those on the first or feed side, the components evaporate after passing through the membrane and thus form a vapor permeate. This process is therefore known as "pervaporation". Due to the difference in permeabilities of the components of the liquid mixture, the permeate has a different composition than the liquid on the feed side, so the liquid is separated into its various components.
Under the assumption that a sufficiently high difference in vapor partial pressures is maintained between the feed side of the membrane and the permeate side, the separation efficiency of a given membrane with regard to a given feed liquid depends only on the permeabilities of the components in question. Only nonporous membranes can be used for pervaporation. This means that the membrane does not have continuous pores large enough for the liquid, especially the liquid mixture, to be able to flow through the membrane through its pores as a result of the pressure difference. It is generally assumed that the solubility of one component in the membrane material, together with the diffusion behavior, controls the mass transport through the membrane. Pervaporation is a dynamic nonequilibrium process in which transport phenomena determine the separation efficiency of a membrane.
The process of pervaporation with the help of membranes is generally known and has been described in the literature (see S. K. Hwang, K. Kammermeyer, Membranes in Separation, John Wiley & Sons, New York, 1975; R. Rautenbach, R. Albrecht, J. Membr. Sci., 7 (1980); G. Tusel, H. Bruschke, Desalination. 53 (1985); J. Neell et al., Desalination, 53, 1985 (297) and J.-P. Brunn et al., J. Membrane Science. 25 (1985) 55).
Since the separation efficiency of a membrane used for pervaporation is determined by transport phenomena as mentioned above, the nature of the material used to produce the membrane is especially important. It is known in this regard that the properties of certain plastics can be modified by treatment with physical and chemical agents in such a way that they are rendered especially suitable for use in pervaporation. One such process is described, for example, in German Patent DE-A 3,515,184.6 where homogeneous, dense films are irradiated with accelerated electrons and then subjected to radical graft copolymerization with monomers whereby groups capable of forming a salt with the help of the monomers are introduced into the polymer.
The polymer then has ion exchange properties and in the salt form of ion exchange it has an especially good selectivity for use in pervaporation.
Membrane materials, according to German Patent DE-A 3,515,184.6, gradually lose their good properties with respect to high selectivity and high permeate flow in unavoidable ion exchange. Membranes according to German Patent DE-A 3,514,184.6 [sic; 3,515,184.6] therefore cannot be used in the long run for separatio
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Chemical Abstract, 96:218326q, Le Chau Thanh, et al., Single-Stage Synthesis of a Graft Copolymer of Cellulose with Polyampholyte Properties, 1982.
Brueschke Hartmut E. A.
Ellinghorst Guido
Niemoeller Axel
Tuesel Guenter F.
Chapman Mark A.
Deutsche Carbone AG
McCamish Marion E.
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