Preparation, characterization, acid stability and organic fouling of poly(acrylonitrile-co-methacrylic acid) ultrafiltration membranes

Poly(acrylonitrile-co-methacrylic acid) (PANMA) ultrafiltration membranes were prepared according to phase-inversion method using a semi-automatic mechanical casting unit. Membranes were made using casting dopes containing PANMA (16-22%) and polyvinylpyrrolidone (0-2%) in dimethylformamide or the mixture of dimethylformamide (DMF) and tetrahydrofuran (THF). SEM micrographs showed the presence of finger-like macrovoids and tear drop shape-like cavities under the dense skin layer for the membranes prepared using the casting dope containing 16-18% and 20-22% PANMA, respectively. The pure water fluxes were in the range of 756-78 and 246-52 L/m(2).h at 3 kg/cm(2), and the molecular weight cut off values were found to be in the range of 96-112 kDa and 92-102 kDa, respectively, for the membranes prepared using the casting dope in DMF and DMF+THF. Fouling tendency of the membranes was studied by permeating aqueous solution of PEO-100 kDa and measuring the trend in the flux with time. The flux recovery ratio values were in the range of 93-99%, thus indicating that the membranes have excellent fouling resistant nature. Acid stability measurements have shown that the flux was decreased by 13-16% while, there was no significant change in the rejections of the membranes which were immersed in 5-20% sulphuric acid solution for 12 months. (C) 2011 Elsevier B.V. All rights reserved.