PVDF/HMO ultrafiltration membrane for efficient oil/water separation

Xylem-Inspired Hydrous Manganese Dioxide/Aluminum Oxide/Polyethersulfone Mixed Matrix Membrane for Oily Wastewater Treatment

Ultrafiltration membrane has been widely used for oily wastewater treatment application attributed to its cost-efficiency, ease of operation, and high separation performance. To achieve high membrane flux, the pores of the membrane need to be wetted, which can be attained by using hydrophilic membrane. Nevertheless, conventional hydrophilic membrane suffered from inhomogeneous dispersion of nanofillers, causing a bottleneck in the membrane flux performance. This called for the need to enhance the dispersion of nanofillers within the polymeric matrix. In this work, in-house-fabricated hydrous manganese dioxide-aluminum oxide (HMO-Al₂O₃) was added into polyethersulfone (PES) dope solution to enhance the membrane flux through a xylem-inspired water transport mechanism on capillary action aided by cohesion force. Binary fillers HMO-Al₂O₃ loading was optimized at 0.5:0.5 in achieving 169 nm membrane mean pore size. Membrane morphology confirmed the formation of macro-void in membrane structure, and this was probably caused by the hydrophilic nanofiller interfacial stress released in PES matrix during the phase inversion process. The superhydrophilic properties of PES 3 in achieving 0° water contact angle was supported by the energy-dispersive X-ray analysis, where it achieved high O element, Mn element, and Al elements of 39.68%, 0.94%, and 5.35%, respectively, indicating that the nanofillers were more homogeneously dispersed in PES matrix. The superhydrophilic property of PES 3 was further supported by high pure water flux at 245.95 L/m².h.bar, which was 3428.70% higher than the pristine PES membrane, 197.1% higher than PES 1 incorporated with HMO nanofiller, and 854.00% higher than PES 5 incorporated with Al₂O₃ nanofillers. Moreover, the excellent membrane separation performance of PES 3 was achieved without compromising the oil rejection capability (98.27% rejection) with 12 g/L (12,000 ppm) oily wastewater.

Effect of different factors on treatment of oily wastewater by TiO2/Al2O3-PVDF ultrafiltration membrane

An ultrafiltration membrane developed by our research group was applied to treat simulated emulsified oil wastewater. ATR-FTIR, SEM, TEM, and Zeta potential analyzes demonstrated that the modified ultrafiltration membrane (MM) has excellent stability and anti-fouling capacity than origin membrane (OM), which possesses a pure water flux of 260 L·m^-2·h^-1 and oil/water (o/w) rejection of 98.5 ± 0.33%. Inorganic salt CaCl₂ has more considerable influence than MgSO₄ and NaCl under the same mass concentration in the two membranes UF process. Along with concentration increasing, flux sharply reduces; meanwhile, the rejection has an opposite trend. Moreover, permeation flux has a maximum value, and the rejection also gets its optimal state under neutral conditions during the pH value of 2-12. The membrane also exhibits excellent anti-fouling performance and anti- o/w adsorption properties with an adsorption rate below 0.8% compared with OM, which has an adsorption rate of nearly 2.1%, respectively. A kind of new UF membrane developed by our research group was applied to treat simulated o/w. ATR-FTIR, SEM, TEM, and Zeta potential analyzes demonstrated that PVDF-Al₂O₃/TiO₂ material has excellent stability and anti-fouling capacity. CaCl₂ has the greatest influence than MgSO₄ and NaCl under the same mass concentration. Moreover, permeation flux has maximum value and the rejection also gets its optimal state under neutral conditions during pH 2-12. The membrane also exhibits excellent anti-fouling performance and anti-O/W adsorption properties with adsorption rate below 0.8% compared with OM which has an adsorption rate nearly 2.1%, respectively.