Effect of salinity on hydroxyapatite nanoparticles flooding in enhanced oil Recovery : A mechanistic study

Fluid-fluid interactions can affect any enhanced oil recovery (EOR) method, including nanofluid (NF) brine-water flooding. Flooding with NFs changes wettability and lowers oil-water interfacial tension (IFT). Preparation and modification affect the nanoparticle (NP) performance. Hydroxyapatite (HAP) NPs in EOR are yet to be properly verified. HAP was synthesized in this study using co-precipitation and in situ surface functionalization with sodium dodecyl sulfate in order to investigate its impact on EOR processes at high temperatures and different salinities. The following techniques were employed, in that sequence, to verify its synthesis: transmission electron microscopy, zeta potential, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, particle size analysis, and energy-dispersive X-ray spectra. The outcomes showed the production of HAP, with the particles being evenly dispersed and stable in aqueous solution. The particles' surface charge increased from -5 to -27 mV when the pH was changed from 1 to 13. The HAP NFs at 0.1 wt % altered the wettability of sandstone core plugs from oil-wet at 111.7 to water-wet at 9.0 contact angles at salinity ranges of 5000 ppm to 30,000 ppm. Additionally, the IFT was reduced to 3 mN/m HAP with an incremental oil recovery of 17.9% of the initial oil in place. The HAP NF thus demonstrated excellent effectiveness in EOR through IFT reduction, wettability change, and oil displacement in both low and high salinity conditions

Facile purification of palygorskite and its effect on the performance of reverse osmosis thin film nanocomposite membrane

BACKGROUND: Palygorskite (PAL) is a naturally occurring nanoclay characterized by a distinctive tubular structure and fibrous morphology, exhibiting chemical and thermal stability as well as large specific surface area. The tubular structure of PAL promotes the selective transportation of water molecules, hence can serve as an interesting candidate for liquid separation. In this work, a membrane substrate was fabricated using the purified PAL to enhance the flux of the thin film composite reverse osmosis. Purification of PAL enhances its interaction with polymer chain to further promote nanofiller dispersion and improves the hydrophilic properties. The water flux as well as salt rejection of the developed membranes was examined using a dead end filtration system. The membrane performance with respect to pure water flux and salt rejection was evaluated using reverse osmosis water and 2000 ppm sodium chloride solution at 15 bar operation pressure. RESULTS: The physico-chemical characterization evidenced the role of purified PAL (P-PAL) in increasing the number of pores and promoting the formation of finger like structure in the substrate layer. The water flux of thin film nanocomposite (TFN) containing P-PAL exhibited 114.6% and 43.1% improvement compared to that of neat and TFN membrane incorporated with pristine PAL respectively without compromising the salt rejection performance. CONCLUSIONS: This study highlights the purification of palygorskite and its effects on membrane water permeability in the field of water desalination. © 2021 Society of Chemical Industry (SCI)