METHOD OF MANUFACTURE OF ION EXCHANGE TWO-LAYER MEMBRANE Russian patent published in 2018 - IPC B01D67/00 

FIELD: technological processes.

SUBSTANCE: invention relates to a membrane technique, in particular to methods for the preparation of ion-exchange asymmetric membranes. Solution of perfluorosulfopolymer in lithium form in a solvent – dimethylformamide with a mass fraction in a solution of 7.2 %, volume 15–25 ml – is poured into a glass mold with a flat bottom and held for 2–6 hours until the liquid is evenly distributed over the mold surface, followed by the removal of air bubbles. Liquid form is then heated at a temperature of 50–80 °C until the solvent evaporates completely to form the first membrane layer. Further, a solution of the perfluorosulfopolymer in a lithium form is mixed in a solvent – dimethylformamide with a mass fraction in a solution of 7.2 %, volume 4–10 ml, the modifier in the form of halloysite nanotubes and an additional portion of the solvent – dimethylformamide of 4–10 ml volume – to obtain a suspension. Resulting first layer of membrane, heated to a temperature of 50–80 °C, with the help of an airbrush, the resulting suspension is sprayed at a rate of 0.1–0.5 ml/min at a pressure of 1.5–3.0 atm. Resulting two-layer membrane is then dried at a temperature of 80–120 °C to a constant mass of the membrane to remove the residual solvent for 1 to 5 hours and remove the formed two-layer membrane from the surface of the glass mold with a thickness of the first layer exceeding the thickness of the second layer.

EFFECT: technical result is achieved due to the formation of a clear interface between the layers of the membrane, which ensures a high physical affinity of the membrane layers, which results in the achievement of low values of the diffusion permeability coefficient.

1 cl, 1 dwg, 3 tbl, 2 ex