Polybenzimidazole based membrane for deacidification

A membrane for deacidification, wherein said membrane is prepared by a process comprising:

• a) preparing a blend pre-membrane by dissolving a polybenzimidazole (PBI) and a aromatic polyester (PAr) in appropriate proportion in a first solvent and subsequently evaporating the first solvent;
• wherein
• said polybenzimidazole comprises recurring units of the formula II
• (i) wherein, R belongs to the tetraamine monomer having structure III(a)-III(f) and R′ is from dicarboxylic acid as shown in structure IV:
• wherein, each of R1, R2, R3, R4is independently selected form a group consisting of H, CH3, CF3, F, Cl, Br, I, NO2 or C1-24 alkyl or aryl groups and X can be any of the following:
• —CH2—, —O—, —SO2—, —C(CH3)2—, —C(CF3)2—, —C(Ph)2-, —CH3C(Ph)-, —CH3C(isopropyl)-, —CH3C(t-butyl)-, —CH3C(n-propyl)-, —CH3C(ethyl)-or any other C1-24 alkyl or aryl groups,
• where, k=1-30 containing alkyl, aryl, aromatic ring, arylene, alkylene, arylene-ether or heterocyclic ring such as pyridine, pyrazine, furan, quinoline or thiophene groups as straight chain, branched, cyclic, aromatic or combination of these;
• Y═O, N, S, halogen or combination thereof, n=0-10 and m=appropriate numbers of hydrogen (ii) the aromatic polyester has recurring units of structural formula V
• wherein, R″ is derived from phenolphthalein or its derivatives as shown in formula VI and R′″is from dicarboxylic acid as shown in IV:
• wherein R1-R4 are as defined above,
• b) leaching out the polyester from the pre-membrane by treating the pre-membrane with a base solution at a temperature ranging between 20 to 80° C. for a period ranging between 1 to 15 days, and
• c) washing the membrane with a second solvent,
• wherein the membrane has molecular size porosity.