With the advancement of oil field development, oil and gas exploration has gradually shifted to low-permeability reservoirs. When polymer flooding is applied in these reservoirs, the primary challenge is that polymer molecules have a larger size and struggle to enter the pore spaces in the reservoir. To address this issue, this study utilizes a nanocomposite polymer flooding system, leveraging the synergistic effects of nanometer-sized particles to reduce the size of polymer aggregates and thus improve displacement efficiency. To verify the improvement in polymer flooding performance for low-permeability reservoirs, this study conducted several experimental evaluations. First, dynamic light scattering was used to examine the effect of a nanofluid (iNanoW) on the size of the polymer aggregates. The results showed that iNanoW reduced the size of the polymer aggregates by approximately 40%. Next, rheological performance testing revealed that, compared to the original polymer solution, the viscosity of the iNanoW-polymer compound solution remained basically unchanged, while the elastic modulus decreased by about 9%. Finally, nuclear magnetic resonance (NMR) technology, combined with a conventional core flooding setup, was used to compare the displacement performance of polymer flooding and iNanoW-polymer compound flooding in low-permeability cores with a gas permeability of 50 mD. The evaluation was conducted based on injection pressure, NMR T 2 spectra, and core segmentation sequences. The results show that, compared to traditional polymer flooding, iNanoW-polymer compound flooding allows the polymer fluid to enter smaller and more core pores, thereby expanding the fluid's swept volume. In both small and medium-sized pores in the core, the fluid swept volume increased by approximately 30%. This outcome provides valuable insights for the future application of nanomaterial-polymer compound flooding in low-permeability reservoirs.

Microemulsions are one of the most promising directions in enhanced oil recovery, but conventional screening methods are time-consuming and labor-intensive and lack the means to analyze them at the microscopic level. In this paper, we used the Clint model to predict the changes in the synergistic effect of the mixed system of anionic surfactant sodium dodecyl benzenesulfonate and nonionic surfactant polyethoxylated fatty alcohols (C12E6), generated microemulsions using surfactant systems with different mole fractions, and used particle size to analyze the performance and stability of microemulsions, analyze the properties and stability of microemulsions using particle size, and analyze the interfacial behaviors and changes of microemulsions when different systems constitute microemulsions from the point of view of mesoscopic microemulsion self-assembly behaviors by combining with dissipative particle dynamics. It has been shown that microemulsion systems generated from anionic and nonanionic surfactants with a synergistic effect, based on the Clint model, exhibit excellent performance and stability at the microscopic level. The method proposed in this paper can dramatically improve the screening efficiency of microemulsions of anionic and nonanionic surfactants and accurately analyze the properties of microemulsions, so as to provide a theoretical basis for the subsequent research on microemulsions.

Developing a highly efficient, cost-effective, and stable bifunctional electrode for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is still a major challenge. This work reports on a novel method for fabricating TiN ceramic membrane supported nitrogen-incorporating NiCo2 nanowires (NiCo2-N/TiN) as a bifunctional electrode. Owing to its unique structure, the ample reaction sites available, and the enhanced mass/ charge transport ability, the NiCo2-N/TiN electrode exhibits efficient catalytic performance both in HER and OER, with overpotentials of 131 mV at 20 mA.cm(-2) for HER and 330 mV at 20 mA.cm(-2) for OER, together with excellent stability in alkaline solution. The NiCo2-N/TiN electrode only requires a cell voltage of 1.71 V to drive the current density of 20 mA.cm(-2) for overall water splitting, which exhibits excellent stability for more than 100000 s. Accordingly, the produced ceramic membrane electrode has a great potential for application in industrial hydrogen production.

The sedimentation characteristics of quartz particles affect their separation and settling dehydration processes. Particle morphology determines the sedimentation equilibrium velocity. In this paper, the sedimentation of a single quartz particle is characterized by employing experimental and CFD-DEM approaches. SEM served to examine quartz particles measuring 30–500 μm, and they exhibited flaky–blocky morphologies with an average long–middle axis ratio of 1.6. Consistent with the SEM-detected morphological features of the quartz particles, suggested here is a simpler drag coefficient model, followed by verification of the model with experimental data. The results show that the velocity of a quartz particle in the non-settling direction had a fluctuation of ±0.2 mm/s. The fluctuation reached 0.4 mm/s at varying settlement release angles. The order in which the particles reached sedimentation equilibrium velocity during the settlement process was double-cone, single-cone, and square when the initial velocity was greater than sedimentation equilibrium velocity. Furthermore, the long–middle axis ratio of quartz particles diminished as their equilibrium sedimentation velocities rose. Given that the quartz particles ranged from 30 to 50 μm in size, the long–middle axis ratio wielded no discernible effect on the sedimentation equilibrium velocity.

The fine quartz particle hydration and effects of metal ions on the hydration characteristics of fine quartz surface are investigated using the rheological experiment. Several important factors affecting hydration factors, such as particle sphericity, solution pH, ion species, ion concentration were investigated. The results show that viscosity and hydration factor of fine quartz suspension increase with the increase of solution pH. wherein quartz particles have more negative charges on the surface in alkaline environment and strong hydration repulsion; The introduction of metal ions enhances the hydration strength of fine quartz surface to a certain extent. In contrast, high valence and high concentration will increase the viscosity of fine quartz suspension, and the hydration factors of particle surface also increase. At the same ion concentration, the order of influence on the hydration factors of fine quartz particles is Mg2 + > Ca2+ > Na+ > K+. This finding has been attributed to the combination of metal ion hydration and its adsorption on the mineral surface. This study will provide the theoretical guiding significance for the refractory coal slime water and other mineral processing wastewater containing quartz particles.

The industrial application of powder‐based catalytic electrodes is heavily restricted by powder shedding, inhibition of active sites, and poor long‐term stability. Herein, a porous titanium carbonitride (TiC 0.5 N 0.5 ) ceramic substrate with open straight finger‐like holes is first made by a simple approach of phase‐inversion tape‐casting and pressureless sintering, and then a Co x Ni 1‐ x P active layer is in situ formed by a hydrothermal technique and phosphorization to achieve integrated Co x Ni 1‐ x P/TiC 0.5 N 0.5 self‐supported ceramic electrodes. Electrochemical tests reveal that the optimized Co 0.9 Ni 0.1 P/TiC 0.5 N 0.5 electrode exhibits overpotentials of 76.5 and 79.8 mV at 10 mA cm −2 , Tafel slopes of 47.3 and 40.5 mV dec −1 , in 0.5 m H 2 SO 4 and 1 m KOH, respectively. Furthermore, its superior long‐term stability and resistance to corrosion can be achieved for more than 20 h in both media at 100 mA cm −2 . In addition, the Co 0.9 Ni 0.1 P/TiC 0.5 N 0.5 electrode has much better performance than Pt/C at high current density in neutral media. Density functional theory calculations confirm that the Ni substitution of 1/10 Co in CoP leads to the more optimal |Δ G H* | among the Co x Ni 1‐ x P catalysts. Compared with other CoP or NiP‐based electrodes, the Co 0.9 Ni 0.1 P/TiC 0.5 N 0.5 electrode benefits from high strength, unique pore structure, tight and compatible bonding, and high hydrophilicity.

Developing an economical, durable, and efficient electrode that performs well at high current densities and is capable of satisfying large-scale electrochemical hydrogen production is highly demanded. A self-supported electrocatalytic "Pt-like" WC porous electrode with open finger-like holes is produced through industrial processes, and a tightly bonded nitrogen-doped WC/W (WC-N/W) heterostructure is formed in situ on the WC grains. The obtained WC-N/W electrode manifests excellent durability and stability under multi-step current density in the range of 30-1000 mA cm-2 for more than 220 h in both acidic and alkaline media. Although WC is three orders of magnitude cheaper than Pt, the produced electrode demonstrates comparable hydrogen evolution reaction performance to the Pt electrode at high current density. Density functional theory calculations attribute its superior performance to the electrode structure and the modulated electronic structure at the WC-N/W interface.

Binder-free, cost-effective, and stable hydrogen evolution reaction electrocatalytic electrodes with a customized size are urgently needed for large-scale industrial hydrogen production. Toward this challenge, self-supported TiC@MoS2 (TCMS) ceramic membrane electrodes were fabricated by a self-template strategy. Porous TiC ceramic membranes with straight finger-like pores were first fabricated by phase inversion tape-casting and sintering. Then, a 1T-2H MoS2 nanosheet layer grew on the porous conductive TiC skeleton. The high conductivity of the TCMS skeleton promotes charge transfer, while the porous structure, which consists of abundant finger-like and cavernous pores, favors proton transfer and bubble transfer during the electrolysis process. The optimal TCMS composition displayed an overpotential of -127 mV at -10 mA.cm(-2), a Tafel slope of 41 mV.dec(-1), and an extremely high electrochemical active area of 1079.4 mF.cm(-2) as well as remarkable stability in 0.5 M H2SO4. A high Faradaic efficiency of 99.7% was also achieved. The superior electrocatalytic performance was ascribed to the synergistic effect of the tight bonding and the crystal matching between TiC and MoS2, the unique dual pore structure, the abundant exposed active sites of MoS2 nanoflakes, and the high 1T-MoS2 content. First-principles density functional calculations showed that the 1T-MoS2/TiC hybrid has the lowest free energy for H adsorption (0.116 eV) and the highest density of states near the Fermi level, which leads to a strong catalytic activity.

Fine kaolinite particles are mineral particles that are found in mine wastewater. The particles' shape is one of the parameters that causes a significant change in the sedimentation dynamics in water environments. In this work, experimental methods and Computational Fluid Dynamics Discrete Element Method (CFD-DEM) methods served to investigate the dynamic characteristics of fine kaolinite particle sedimentation. The Results of statistical analyses show that the length-width ratio of fine kaolinite particles is 1-3 and the average simplified spherical coefficient is 0.625 in the 50-500 mu m particle size range. The simplified spherical coefficient formula proved to be effective according to experimentation and simulations. Moreover, the effects of particle size, liquid viscosity, and liquid velocity on kaolinite particle sedimentation dynamic characteristics were numerically studied in detail by using the modified spherical coefficient. The simulation revealed that an increase in liquid viscosity resulted in a declining particle terminal velocity. However, the sensitivity of the particle terminal velocity affected by liquid viscosity fell when the particle size also declined. When an increase in particle size occurred, the sensitivity of the particle terminal velocity to the influence of upwelling water decreased. (C) 2020 Elsevier B.V. All rights reserved.

The adsorption behavior and bridging mechanism of NPAM and kaolinite in aqueous solution were investigated using MD simulation and experiment. Turbidity, Zeta potential, and floc size were involved in the analysis of the settlement test; microscopic interaction mechanisms were further discovered via interaction energy, number and water density distribution, and self-diffusion coefficient. It emerged that too little NPAM has a high diffusivity in bulk water, NPAM cannot be directly adsorbed to kaolinite surfaces and the bridging mechanism is difficult to appear; experiment results in the high turbidity of the supernatant and inability to form flocs. As the number of chains increases, the adsorption probability and the adsorption capacity of NPAM on kaolinite surfaces are improved, the range of NPAM diffusion in bulk water expands and the bridging performance is enhanced; the turbidity decreases and the floc formation. When the number of NPAM chains is excessive, the interaction energy of NPAM in surface water with kaolinite surfaces is slightly weakened, NPAM in bulk water may weaken the combined affinity, but the bridging effect is further enhanced; which increases the turbidity and floc size. The adsorption of NPAM in surface water and kaolinite surfaces is the prerequisite for the formation of bridging mechanism, NPAM in bulk water is the crux to enhancing bridging performance. A large number of water molecules and NPAM have strong competitive adsorption on kaolinite surfaces. The interaction energy between NPAM and kaolinite surfaces in aqueous solution is mainly contributed by van der Waals interaction.

Electrode design and fabrication are of major importance for hydrogen evolution reaction applications, as far as high-efficiency and low-cost production of hydrogen are concerned. This paper reports on a titanium-nitride-ceramic-membrane electrode modified by MoS2 nanoflakes. Porous TiN-ceramic membranes were fabricated by phase-inversion tape-casting, followed by pressureless sintering. The as-prepared TiN membranes contained straight finger-like pores with an average diameter of 80 mu m and smaller pores with an average diameter of 1-3 mu m. Then, MoS2 nanoflakes were perpendicularly, densely, and uniformly grown on the surface of the TiN grains through the one-pot hydrothermal method. The optimized MoS2/TiN membrane electrode displayed a low overpotential of 113 mV at 10 mA cm(-2), a Tafel slope of 78 mV dec(-1), a small charge transfer resistance of 1.44 Omega, and a high double-layer capacitance of 504 mF cm(-2). It also exhibited excellent stability with slight degradation after 80 h testing at an overpotential of 150 mV in 0.5 M H2SO4. The high conductivity of the TiN substrate, the similar chemical bonds, which favored the rapid electron transfer between MoS2 and TiN, the abundant exposed active sites of MoS2 nanoflakes, and the unique dual-pore structure resulted in the above superior electrocatalytic activity. The proposed successful utilization of conventional ceramic-membrane technology to prepare electrocatalysts based on membrane electrodes has potential for large-scale application in industrial hydrogen production.

The objectives of this study are to explore the adsorption mechanisms for how the polyacrylamide (PAM) interact with kaolinite (0 0 1) surface. Three structural unit models (P-AM, P-AA, and P-DAC) were developed from the structure of PAM. The adsorption energies were calculated with density functional theory (DFT) to determine the optimal adsorption system of PAM structural units on the kaolinite (0 0 1) surface. From the Mulliken population analysis, electron density difference, electronic density of states, and electron localization function of the optimal adsorption system, the adsorption mechanism of each adsorption system was derived and their differences were understood. The results show that these reactive sites of the three PAM structural units are O atoms. P-AM and P-AA can be adsorbed on the kaolinite (0 0 1) surface by forming hydrogen bonds. The interaction of kaolinite (0 0 1) surface using P-DAC is driven by both hydrogen bonds and electrostatic attraction, electrostatic attraction as a prevailing role is determined simultaneously. The strength of the hydrogen bonds of the P-AM adsorbed on the kaolinite (0 0 1) surface is higher than that of P-DAC and P-AA. However, the order of the adsorption interaction of the PAM structural units adsorbed onto the kaolinite (0 0 1) surface is P-DAC > P-AM > P-AA.