Obtaining and properties of ultrafiltration cellulose acetate membranes on a nylon net support

Abstract

Composite membranes nylon-AC (NAC) were obtained by immersing a nylon mesh substrate in a 5 % solution of cellulose acetate (AC) in acetone. The AC content in the membrane ranged from 21 to 45 %, depending on the number of applied surface layers. According to the results of studying the properties of composite membranes, an increase in water absorption and total porosity of membranes after the application of the first layer of AC was found, and with the application of the next layer of AC, the values of water absorption and total porosity slightly decrease, which is due to the compaction of the membrane structure. Also, a decrease in the contact angle of the membrane wetting by 33° was revealed, which means an increase in the hydrophilic properties of the membrane, which increases the wettability and productivity of the obtained membranes. Composite membranes with two and three layers of AC: NAC2 and NAC3 were used to separate 0.5 % water-oil emulsion with particle sizes from 81 to 422 nm. The specific productivity of the NAC2 membrane by 0.5 % water-oil emulsion was 9433 dm3/(m2·h), the productivity of the NAC3 membrane was 3799 dm3/(m2·h) at a pressure of 0.55 MPa, which exceeds the performance of the commercial ultrafiltration membrane UPM-100 equal to 1843 dm3/(m2·h). According to the results of the study, the retention capacity of composite membranes for oil products from a water-oil emulsion was established, which was 61 % for NAC2 membranes and 75 % for NAC3 membrane. These indicators are not inferior to the retention capacity of a commercial ultrafiltration membrane of the UPM-100 brand.