Stimuli-Responsive Track-Etched Membranes for Separation of Water–Oil Emulsions

Indira B. Muslimova, Zh. K. Zhatkanbayeva, Dias D. Omertassov, Galina B. Melnikova, Arman B. Yeszhanov, Olgun Güven, С. А. Чижик, Maxim Vladimirovich Zdorovets, Ilya V. Korolkov

Membranes, 2023

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DOI 10.3390/membranes13050523
Data confidence 85 high
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Abstract

In this work, we have developed a method for the preparation of pH-responsive track-etched membranes (TeMs) based on poly(ethylene terephthalate) (PET) with pore diameters of 2.0 ± 0.1 μm of cylindrical shape by RAFT block copolymerization of styrene (ST) and 4-vinylpyridine (4-VP) to be used in the separation of water-oil emulsions. The influence of the monomer concentration (1-4 vol%), the molar ratio of RAFT agent: initiator (1:2-1:100) and the grafting time (30-120 min) on the contact angle (CA) was studied. The optimal conditions for ST and 4-VP grafting were found. The obtained membranes showed pH-responsive properties: at pH 7-9, the membrane was hydrophobic with a CA of 95°; at pH 2, the CA decreased to 52°, which was due to the protonated grafted layer of poly-4-vinylpyridine (P4VP), which had an isoelectric point of pI = 3.2. The obtained membranes with controlled hydrophobic-hydrophilic properties were tested by separating the direct and reverse "oil-water" emulsions. The stability of the hydrophobic membrane was studied for 8 cycles. The degree of purification was in the range of 95-100%.