Separation of oil emulsion using polyacrylonitrile membranes, modified by corona discharge

This work investigates the influence of the parameters of a unipolar corona discharge (the treatment time, voltage) on the performance and selectivity of separation of model emulsions “oil in water” based on the oil in the Devonian deposits of the Tomatocage field (Republic of Tatarstan) using polyacrylonitrile membranes with a molecular weight cutoff of particles of 60 kDa. The values of chemical oxygen demand of the original emulsions and filtrates are determined. The values of the processing time (30 s) and voltage of the corona (5 kV) on membranes which achieved the best performance and selectivity of the separation process of oil-water emulsion are determined. The methods of lying drop, X-ray diffraction, and atomic force microscopy showed changes in the surface structure and internal structure of the treated membrane. In particular, there was decrease in the wetting angle from 45.1° to 43.3° and an increase in the degree of crystallinity from 0.15 to 0.18, which was due to the flow on the surface of the PES membrane processes of etching and oxidation resulting from exposure to a unipolar corona discharge ozone, which is also confirmed by images of the surface of the filter elements and the histograms of the topography, on the basis of which it showed a decrease in height and number of protrusions from 42 nm and 7500 to 10 nm and 2500.