Influence of metal salts in reaction medium on performance enhancement of novel aliphatic-aromatic-based polyamide thin-film composite osmosis membranes

• Published in: Separation science and technology 2019-05, Vol.54 (8), p.1363-1375
• Main Authors: Ghosh, Bitan, Ghosh, A.K., Bindal, R.C.
• Format: Article
• Language: English
• Subjects: Aliphatic compounds; Aluminum sulfate; Amines; Anions; Aramid fibers; Aromatic compounds; Atomic force microscopy; Benzene; Chlorides; Contact angle; Fluctuations; Flux; Inorganic salts; Kinetics; Membrane permeability; Membranes; Metal concentrations; Metal ions; metal salts; Metals; Microscopy; Molecular weight; osmosis; Performance enhancement; Permeability; polyamide; Polyamide resins; Polyamides; Polycondensation reactions; Polyethylene; Polyethylenes; Polysulfone; Polysulfone resins; Reaction kinetics; Reverse osmosis; Salt rejection; Salts; Sulphates; Thin films; thin-film composite
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1080/01496395.2018.1532963

In this study, we report an easy and novel way to develop high flux aliphatic-aromatic-based thin-film composite (TFC) polyamide osmosis membranes by addition of inorganic metal salts with amine reactants in the reaction system of polyethylene imine (PEI) and 1,3-benzene dicarbonyl chloride. Inorganic metal salts like CuSO 4 , NiSO 4 , MgSO 4 , and Al 2 (SO 4 ) 3 added to block some of the amine groups of PEI through complexation which in turn changes the polycondensation reaction kinetics of amine acid chloride reaction. The prepared membranes were characterized using water contact angle and atomic force microscopy studies and the performances were evaluated both in reverse osmosis and forward osmosis mode. In presence of metal salts in reaction interface, the performance of TFC membranes was greatly enhanced and the optimum metal salt concentration was identified for individual metal salts for maximum performance enhancement. The effects of different anions for same metal ion and different molecular weight of PEI were evaluated on composite polyamide membrane performances. Water permeability (flux) of 63.48 L m −2  h −1 was achieved upon inorganic salt addition compared to the unmodified TFC membranes with flux of 42.1 L m −2  h −1 at similar salt rejection of ~95%. Based on the new findings, a conceptual model was proposed to explain the role of metal ion in amine solution on the resulting characteristics of aromatic-aliphatic type polyamide-polysulfone composite membrane.