Enhancement of Separation of Water–Oil Emulsion Using Unipolar Corona-Treated Polysulfonamide Membranes

Abstract

The influence of unipolar-corona discharge treatment on the efficiency of separation of a model oil-in-water emulsion using polysulfonamide membranes with a molecular weight cut-off of 20 kDa (pore size ≈ 0.01 μm) has been investigated. It has been shown that the corona discharge treatment of the membranes leads to the intensification of the separation of water–oil emulsions and the process parameters depend on the processing time and the voltage applied to the corona electrode. The maximum value of the efficiency (95.4%) is noted in the case of the membrane treated in a corona discharge for 5 minutes at a voltage of 5 kV applied onto the electrode. The trends observed have been explained. It has been shown that the corona treatment promotes the hydrophilization of the membrane surface: the contact angle of water is α = 55° for the initial membrane and α = 50° after the corona treatment. Atomic force microscopy has shown a change in the structure of the membrane surface by the corona treatment—an increase in the roughness. A small decrease in the crystallinity of polysulfonamide by its treatment in a unipolar corona discharge has be been revealed.