High flux and fouling resistant reverse osmosis membrane modified with plasma treated natural zeolite

Polyamide reverse osmosis (RO) membrane was fabricated by interfacial polymerization of m-phenylenediamine and trimesoyl chloride and modified with natural clinoptilolite as a hydrophilic zeolite material embedded in the polyamide layer. The effect of glow discharge plasma treatment with different plasma gas pressures was investigated on the physical and chemical properties of the natural clinoptilolite and the resulted modified membranes. Scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy of the untreated and treated clinoptilolite confirmed the variation of its surface properties and formation of new Si[sbnd]OH[sbnd]Al bonds during the plasma treatment. The embedding of hydrophilic clinoptilolite in the polyamide layer decreased the roughness of membrane surface. Also, the water contact angle of the membranes showed the improved hydrophilicity of the modified membranes which was confirmed with the results of permeation tests. The membrane modified with 0.01 wt.% clinoptilolite treated under 1.0 Torr oxygen as the plasma gas showed the highest water flux improvement (39%) and fouling recovery ratio (88%) compared to the unmodified membrane.