Preparation of inorganic membranes via dip coating and plasma sputtering for the treatment of produced water

Abstract

Produced water, a by-product generated from the oil and gas extraction processes, represents a major challenge in the oil and gas industry as it is generally characterized with a very high salinity and oil content. Currently used ceramic membranes for oil-water separation suffer from the low water flux in spite of their several distinctive advantages. To overcome this limitation and to increase the water flux and oil rejection, commercial ceramic TiO2 membranes were dip coated with silica (SiO2) and alumina (Al2O3) nanoparticles at different concentrations of 0.25, 0.50, 0.75, and 1.0 wt %. Two commercial ceramic membranes were also coated using plasma sputtering with SiO2 and Al2O3 targets. The coated membranes were characterized using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy, porosity, and contact angle, flux and TOC measurements. Results showed that the SiO2 and Al2O3 nanoparticles were successfully deposited on the surface of the dip-coated ceramic membranes confirming the dip coating and sputtering approaches. All the membranes showed great enhancement in their hydrophilicity with 7 of them achieving a zero contact angle. Furthermore, water fluxes of 817, 1084, 1256, 1413 and 3636 LMH were reported at control, SputCA, SputCS, DipCA-50 and DipCS-50; respectively. Where the latter two being the best performing membranes in the alumina dip coated membranes batch and the silica dip coated membranes batch. Finally, total organic carbon (TOC) in the treated water samples reported 100, 28, 28, 18, 9, 9 mg/L at control, SputCA, SputCS, DipCA-50 and DipCS-50 respectively. The DipCS-50 was chosen as the best performance membrane and was then used in an adsorption study that was performed using Fe2O3 nanoparticles to check for the possibility of having an integrated filtration-adsorption system. The Fe2O3 Nps proved to be good oil adsorbers as a 0 mg/L oil content was achieved after adsorption with a 1wt% solution of Fe2O3 and 1000 mg/L oil loaded water sample. Dried Fe2O3 Nps were characterized using FTIR, EDS and SEM to successfully prove the presence of adsorbed organic matter on the Nps. The adsorption process seemed to best fit a Langmuir isotherm and proved to be a promising final polishing step after the PW filtration with ceramic membranes.

Date of Award	Dec 2019
Original language	American English