| abstract |
Carbon sorbents for selective adsorption of low molecular substances from mixts. of these with high molecular substances, are made by first immersing particles of active carbon in a liq. contg. no film-forming polymer, removing excess liq. from the particles, dispersing the particles in a soln. of a film-forming polymer in a solvent, sepg. the particles carrying a layer of the film-forming polymer from the soln., and drying the particles. Pref. the particles are presoaked in a liq. which has limited miscibility with the solvent used in the film-forming polymer soln. Specific examples of such systems are the use of CHCl3 as the liq., and aq. PVA soln. as film former, and ethyl ether as liq. and aq. methylcellulose soln. as film-forming polymer. Alternatively the liq. used may be a solvent having unlimited miscibility with the solvent for the film-forming polymer. Examples of such systems are the use of water as the liq. and an acetone soln. of acetylcellulose as film-former, and the use of hexane as liq., with a cyclohexanone soln. of PVC as film-former. The process gives carbon sorbents of high activity in which the selectivity for the sorption of low molecular materials is not impaired by redn. of the porosity of the material by plugging with film forming polymer. Prods. are useful in chemical processes and in medical applications. |