The membranes utilization in the separation processes is conditioned by a complex morphological, structural and process-performances characterization. the paper presents the ususl characterization methods employed in the micro- and ultrafiltering processes. From the following characterization methods: scanning electron microscopy, bubble-point, mercury porosimetry, gas adsorption-desorption, prmoporometry, thermoporometry, standard systems filtering

The obtaining of teh polisulphone membranes for the purification of the dispersion deys by microfiltration was studied. The phase inversion method makes possible the obtaining of membranes with characteristics enabling the micro- and ultra-filtration and with an asymmetrical structure rendered evident by electron scanning microscopy. The performances of the obtained membranes have been determined by the exploitation conditions (flow conditions, pressure,

The analysis of literature data made possible the presentation on the main phenomena occuring in teh separation processes with the help of membranes. This first section of the paper deals with the general models of transport through membranes, establishing correlation among the preparation methods and the chemical structure of the materials and the microstructure of the separated system. By a complex characterization of the membranes, the application

The influence of anionic and cationic surfactants, employed in preparation of asymmetric polysulfone membranes upon microfiltration of colloidal dispersion was studied. The cationic surfactants modify the morphology of membranes favouring the obtaining of fluxes and retentions higher than those of membranes with anionic surfactants. The decrease of the average diameter of permeate particles depends on the chemical nature of cationic surfactant; the

This work deals with obtaining of asymmetric membranes by phase inversion method, induced by chemical reaction. The investigation were carried out on a polymer-solvent-nonsolvent system with polyamide-6 as polymer, formic acid as solvent and aqueoue base solutions (NaOH, NH3) as nonsolvents. the following variants of chemical reactions which induce phase inversion were studied: decomposition of the solvent in nonsolvent, reaction between the solvent

The results of study onthe obtention of asymmetric membranes by phase inversion method are presented: the study has evidenced the generality of coagulation pathway theory developed by the Dutch membrane school. Simple structures were obtained by changing either the solvent or coagulant in the polymer-solvent-nonsolvent system. In this study use has been made of polysulfone as reference polymer, dipolar aprotic solvent (DMF, NMP, DMAc, Chloroform,

A sulfonate semipermeable membrane was studied for separation two phase, one of 3% solution CuSO4.5HOH, ZnSO4.7HOH and MnSO4.HOH, the latter made invariably of KCl sat/1000. The former phase was permanently strred, while the latter was redox buffered, at various rH values, by means a redoxtron, for 8 hours.The transfer of Cu, Zn, Mn, respectively, from the former towards the latter phase was observed as occuring specifically for each metal, the membrane

Application of phase inversion method, in particular immersion-precipitation technique has allowed the obtaining of polysulfone and polyphenyleneoxide membranes from solutions of aprotic solvents as: dimethylformamide, dimethylacetamide, N-methylpirolidone, chloroform and trichlorethylene. The membranes were obtained according to the pathways indicate by Smolders on polymer-solvent-non-solvent phase diagram.

Microprous polyethersulfone membranes with asymmetric structure were prepared by phase inversion method. The influence of solvent, coagulation agent and additions of polyethylene glycols with various molecular weights was studied. The membrane morphology was characterized by scanning electron microscopy and their hydrodynamic properties by solvent permeation and standard system filtering. The results recommend these membranes for utilization in micro-

p-tert-buthylthiacalix[4]arene, in which the four methylene bridges of p-tertbthylcalix[4]arene are replaced by sulfide linkages, is conveniently synthesized from mixture of p-tertbuthylphenol and elemental sulfur, tested in transport of metal cations through liqud membranes. Membrane system with p-t-buthylthiacali[4]arene as carrier was duble-jet liquid membrane. Pb(2+)cations were tested to verified abiliy of transport of p-t-buthyltiacalix[4]arene.