      AURELIA CRISTINA NECHIFOR 1, 2 , IONELA VERONICA PANAIT 2 , SZIDÓNIA KATALIN TÁNCZOS 2 , MIHAELA NEAGU 2 , DANIELA PASCU 2 , ADRIANA CUCIUREANU 2 1 National Institute for Microtechnologies IMT Bucharest, Str. Erou Iancu Nicolae nr. 126A, 077190 Bucharest 2 Faculty of Applied Chemistry and Materials Sciences Politehnica University of Bucharest 147 Gheorghe Polizu St., Bucharest, 011061 ROMANIA nechiforus@yahoo.com   This work reports the performances of the polysulfone4polyaniline (PSf4PANI) porous composite membranes for proteins recovery. Polysulfone4polyaniline porous composite membranes are obtained by phase inversion with chemical reaction. PANI is obtained  by oxidative aniline polymerization. Composite membranes are morphological studied by electron microscopy and characterized by water solutions permeation at different pH and pressures. Polysulfone4polyaniline porous composite membranes UF processes performances to BSA separation are also reported.   PSf4PANI membranes, phase inversion, hydrodynamic characteristics, rejection, BSA retention.   The membrane techniques that use composite polysulfone membranes are applied in various domains, replacing in many instances the technologies that use simple membranes [1, 2]. Polysulfone (PSf) are a thermoplastic rigid polymer, durable and transparent that maintains its characteristics in a temperature range from 4100 degrees to over 160˚C [3]. Chemical and physical properties of polysulfone including good chemical stability, mechanical strength and resistance to oxidation make it the preferred material for use as membrane substrate [4, 5]. Polysulfone are widely used at the manufacture of membranes for ultrafiltration and gas separation [648]. In particular, polysulfone is used as ion exchange membrane for processes such electrodialysis and electrolysis with polymer electrolyte4membrane [9]. Polysulfone4polyaniline porous composite membranes (PSf4PANI) exhibit an interesting advantage because they use PSf as the base polymer (PSf has good mechanical and chemical properties, good stability in acid and basic aqueous solutions, good solubility in the usually solvents in the process of membrane production) and specially performances in bioanalysis and bioseparations [114 14]. The paper presents the composite PSf4PANI membranes performances obtained by phase inversion, new immersion4precipitation technique with chemical reaction. The morphology and hydrodynamic characteristics are studied, as well as the capacity of separating albumin from bovine serum (BSA) – the reference protein.  ! " !  Polysulfone material used in the present study was obtained from BASF (Ultrason S3010)  Solvents: N methyl pyrrolidone (Merck) and aniline (Merck), p.a. reagent were used as solvents without advanced purification and methanol, ethanol and isopropanol (Merck) and bidistillate water were used as non solvents.  Oxidizers: nitric acid (Merck), ammonium peroxodisulfate (Fluka), potassium persulfate (Merck) and hydrochloric acid p.a. (Merck) were used as 0.140.5 M solution.  BSA – Biochemika, fraction V, ≥92%, M=67.000 g/mol, free protease " #$% &  Polysulfone was dissolved in a solvent mixture from above solvents to form a solution at a preset temperature (25 0 C)  Degassed solution was cast to a glass plate using a Gardner preheated knife.  The thickness filters polysulfone membrane type was 0.340.5 mm. Recent Researches in Environment and Biomedicine ISBN: 978-1-61804-075-6 126