The Effect of Ceramic Membranes’ Structure on the Oil and Ions Removal in Pre-Treatment of the Desalter Unit Wastewater

Salts, organic materials, and hazardous materials can be found regularly in the effluent from a desalter unit of crude oil. These materials should be separated from the wastewater. Four kinds of inexpensive and innovative ceramic microfiltration membranes (mullite, mullite-alumina (MA 50%), mullite-alumina-zeolite (MAZ 20%), and mullite-zeolite (MZ 40%)) were synthesized in this research using locally available inexpensive raw materials such as kaolin clay, natural zeolite, and alpha-alumina powders. Analyses carried out on the membranes include XRD, SEM, void fraction, the average diameter of the pores, and the ability to withstand mechanical stress. Effluent from the desalter unit was synthesized in the laboratory using the salts most present in the desalter wastewater (NaCl, MgCl2, and CaCl2) and crude oil. This synthesized wastewater was treated with prepared ceramic membranes. It was discovered that different salt concentrations (0, 5000, 25,000, 50,000, 75,000, and 100,000 mg L−1) affected the permeate flux (PF), oil rejection, and ion rejection by the membrane. Results showed that in a lower concentration of salts (5000 and 25,000 mg L−1), PF of all types of ceramic membranes was increased significantly, while in the higher concentration, PF declined due to polarization concentration and high fouling effects. Oil and ion rejection was increased slightly by increasing salt dosage in wastewater due to higher ionic strength. Monovalent (Na+) and multivalent (Ca2+ and Mg2+) ion rejection was reported about 5 to 13%, and 23 to 40% respectively. Oil rejection varied from 96.2 to 99.2%.

Superhydrophilicity of $\alpha$-Alumina Surfaces Results from Tight Binding of Interfacial Waters to Specific Aluminols

Understanding the microscopic driving force of water wetting is challenging and important for design of materials. In this work, we investigate, using classical molecular dynamics simulations, the water/$\alpha$-alumina (0001) and ($11\overline{2}0$) interfaces chosen for their chemical and physical differences. There is only one type of aluminol group on the nominally flat (0001) surface but three types on the microscopically rougher ($11\overline{2}0$) surface. We find that both surfaces are completely wet, consistent with contact angles of zero. Moreover, the work required to remove water from a nanoscale volume at the interface is larger for the (0001) surface than the ($11\overline{2}0$) surface, suggesting that the (0001) surface is more hydrophilic. In addition, translational and rotational dynamics of interfacial water molecules are slower than that in bulk water, suggesting tight binding to the surface. Interfacial waters show two major polar orientations, either pointing to or away from the solid surface. In the former case, waters donate strong hydrogen bonds to the surface, while in the latter they accept relatively weak ones from aluminol groups. The strength of hydrogen bonds is estimated using their lifetime and geometry. We found that for all aluminols, water-to-aluminol hydrogen bonds are stronger and have longer lifetimes than the aluminol-to-water ones. One exception is the long lifetime of the \ce{Al3OH}-water hydrogen bonds on the ($11\overline{2}0$) surface, due to geometric constraints. Interactions between surfaces and interfacial waters promote a templating effect whereby the latter are aligned in a pattern that follows the underlying lattice of the mineral surface.

Effect of corrugated minichannel variable width on entropy generation for convective heat transfer of alpha-Alumina-water nanofluid

Energy management and sustainability in thermal systems require maximum utilization of resources with minimal losses. However, it is rarely unattainable due to the ever-increasing need for a high-performance system combined with device size reduction. The numerical study examined convective heat transfer of an alpha-Alumina-water nanofluid in variable-width corrugated minichannel heat sinks. The objective is to study the impact of nanoparticle volume fractions and flow area variation on the entropy generation rate. The determining variables are 0.005 – 0.02 volume fractions, the fluid velocity 3 – 5.5 m/s and heat flux of 85 W/cm2. The numerical results show an acceptable correlation with the experiment results. The results indicate the thermal entropy production drop with an increase in nanoparticles volume fraction. Contrastingly, the frictional resistance entropy suggests the opposite trend due to the turbulence effect on the fluid viscosity. The induction of Alumina-Water nanofluid with enhanced thermal conductivity declined the entropy generation rate compared to water alone. The increase in width ratio by 16% between the cases translates to at least a 9% increase in thermal entropy production. The outcome of this study can provide designers and operators of thermal systems more insight into entropy management in corrugated heatsinks.