Iranian Journal of Chemical Engineering (IJChE)

Abstract Polysulfone-zinc oxide mixed matrix membrane (MMM) was fabricated. A polyamide layer was formed on the top surface of the membranes using interfacial polymerization process. The properties and structure of the membranes were investigated and the membranes were used for desalination in reverse osmosis process. Cross-sectional images of the membranes substrate showed that the addition of zinc oxide to the polymer matrix resulted in a denser structure and increased the thickness of the sponge-like layer near the lower surface of the membrane. The addition of zinc oxide to the polymer matrix decreased the surface contact angle of the membrane with water, thereby increasing the hydrophilicity of the membrane. The pure water flux of all membranes reduced at the beginning of the process and after 60 min remained almost constant at the values of 19.50 (Lm-2h-1) and 30.20 (Lm-2h-1) for the membrane made with plain polymer and the MMM, respectively. In the reverse osmosis process, the water flux of the membrane fabricated using plain polymer was 9.70 (Lm-2h-1) which increased by 39% and reached to 13.50 (Lm-2h-1) by the addition of zinc oxide nanoparticles. The salt rejection of plain polysulfone membrane was 92.5% which increased to 97.21% with the addition of zinc oxide to the polymer matrix. The addition of zinc oxide nanoparticles to the polymer matrix significantly decreased the water permeability to salt permeability ratio (B/A) from 40.54 to 14.35 (kPa).

Abstract Polymer adsorption by nanoparticles improves the stability of these types of suspensions against aggregation. In this work, the surface adsorption of polyethylene glycol (PEG) and polyvinyl alcohol (PVA) with different molecular weights onto the Zinc oxide (ZnO) nanoparticles is studied. The effects of solution pH value and temperature on the adsorption process are also investigated. The ZnO nanoparticles are then analyzed using Fourier transform infra red (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) techniques. The aggregation of nano particles before and after polymer adsorption is also investigated by scanning electron microscopy (SEM). The results show that by adsorbing the PEG and PVA, due to a relatively large electrostatic repulsive force between ZnO nano particles, the size of aggregated nanoparticles decreases. It has also been revealed that the low molecular weight polymers exhibit a higher adsorption rate on the particles’ surfaces in comparison to the polymers with high molecular weight.