Modification of porous polyacrylonitrile membrane

The effects of the modification of polyacrylonitrile ultrafiltration membra nes with sodium hydroxide are discussed. The NaOH-induced hydrolysis of nit rile groups on the membrane surface results in membranes with decreasing po re diameter. The average pore diameter changes from 2.6 to 0.6 nm in the pr ogress of hydrolysis. The modified membranes are less prone for protein dep osition. Fouling causes a pore diameter reduction of 80% for the untreated and 20% for the modified membranes. Modification results also in the creati on of the membranes working in the nanofiltration mode. The unmodified memb rane does not reject salt while a membrane immersed in the modification bat h is capable of rejecting about 50% of calcium carbonate.