Journal of Molecular Liquids最新文献

Solubility data and regularity of 3-methyl-1,2-cyclopentanedione (MCP) in twelve pure organic solvents were investigated by static method under certain conditions. The results of experiments demonstrate that the solubility of MCP is proportional to the temperature. One of the most solubilizing solvents is dichloromethane. A preliminary assessment of the potential for chemical bond formation between the solute and the solvent was conducted by examining electrostatic potential energy surfaces of the solute. The dissolution behavior was explained by physicochemical properties (polarity, hydrogen bond donor–acceptor propensities and cohesive energy density (CED)) of solvent. The results demonstrate that polarity has a more pronounced impact on the dissolution process, but that other properties also effect the dissolution process to some extent. The Density Functional Theory (DFT) was applied to demonstrate interactions between solute and solvent during the dissolution process. Six thermodynamic models (van’t Hoff, Apelblat, Yaws, λh, Wilson, Jouyban) were utilized to fit solubility data. Wilson model exhibits the highest correlation. The thermodynamic properties indicate that the dissolution of the MCP can be described as an entropy-driven process, which is endothermic and spontaneous.

To address the problems of slow crystallization and nucleation in two-phase miscibility in the application of refrigerant hydrates, adding surfactants can be taken as an effective way to promote hydrate formation. Three kinds of polyoxyethylene laurate (LAE) surfactant with different hydrophilic chain lengths (LAE-4, LAE-9 and LAE-24) were selected as accelerators to study their effects on hydrate formation. LAE series surfactants significantly reduce hydrate nucleation induction time. The hydrate induction time of the system with 4.0 wt% LAE-9 is shortest (98 min). The hydrate formation with 4.0 wt% LAE-9 has small randomness and is more stable. Micelles formed by LAE surfactants provide more nucleation sites and accelerate hydrate growth. The hydrate cold storage density is related to the hydrophilic chain length of surfactant. The system with 4.0 wt% LAE-9, which has a suitable hydrophilic chain length, achieves the largest hydrate cold storage density (246.10 kJ·kg⁻¹). Hydrate has the fastest growth rate of 4.80 kJ·kg⁻¹·min⁻¹ in the system with 2.0 wt% LAE-24. There is a “memory” effect during hydrate formation and dissociation cycle, eliminating the need for induction time during hydrate re-formation. Hydrate can be re-formed quickly.

Composites are multiphasic materials that show improved characteristics compared to the consisting components. In nanocomposites, the sizes of components fall in the nano dimension due to which they exhibit extraordinary features compared to normal composites and are explored in numerous areas efficiently. Polyaniline (PANI) is a fascinating conducting polymer (CP) that is extensively utilized in various fields including water remediation and generation of composites of various semiconductor photocatalysts for improvement of photocatalytic efficiency, stability, recovery and recyclability, and reduction of agglomeration and photoinduced dissolution in solution due to extensive delocalized pi-electron system, effective mobility of electrons, lower band gap, and presence of aromatic amine functionalities in the polymer backbone. PANI forms binary and multi-component nanocomposites with photocatalysts such as metal-based (metal, metal oxide, metal sulfide, metal halide, metal ferrites, etc.), and carbon-based (GO, rGO, g-C₃N₄, CNT) which exhibit highly improve photocatalytic performance compared to pristine semiconductor photocatalysts against numerous water pollutants. Usually, PANI in the binary nanocomposites with the metal- and carbon-based semiconductor photocatalysts generates heterojunction structures of type-II, p-n, Z-scheme, and S-scheme and reduces band gap, enhances optical absorbance in visible light, increases separation of charge carriers, and their delocalization and via this prevent charge carriers recombination and their life span due to which photocatalytic performance is amplified. This review study is planned to present a review on PANI based binary nanocomposite photocatalysts, their synthesis, features, and photocatalytic applications for degradation of organic pollutants (dyes, phenolic pollutants, nitroaromatics, pesticide, pharmaceuticals pesticides, etc.) and inorganic pollutants under visible, UV, and solar light exposure at numerous reaction conditions. Moreover, this study highlighted various synthesis procedures of polyaniline and their merits, and demerits, synthesis routes of polyaniline nanocomposites.

The objective of this research was to investigate the healing characteristics of bitumen through the assessment of fatigue-healing performance of SARAs fractions and its characterization at the molecular level with SARAs fractions as the intermediate. Firstly, the flow behaviors and fatigue-healing performance of fractions were characterized by rheometer. Then, the diffusion systems were constructed and the diffusion with preset cracks was carried out, the evaluation of which was identified by density distribution, relative concentration in crack region, mean square displacement and interaction effect. The results indicate that aromatics exhibit the closest similarity to original bitumen in flowing behavior, which also reflected in the healing performance. The healing performance of resins and asphaltenes are extremely limited while that of saturates was comparable to fluid. Molecular simulation was further supporting to investigate the healing process. A platform period was found in the healing period when the molecules would move to seek the lowest energy state which was considered as healing in the alternative perspective. During the period, heavy components were more difficult to traverse while weak interaction between light components would shorten the period and identify the lowest energy state more easily, thereby greatly affecting the healing performance of fractions. Furthermore, heavy components are analogous to anchor points, among which resins were more readily aggregated and asphaltenes were relatively dispersed, while light components diffuse flexibly within them. The diffusion has the potential to drive the movement of heavy components which also kept the capture of other components, ultimately resulting in the formation of a stable healing state. The outcome with a discernible interaction effect would be important theoretical significance for the refinement of bitumen of better healing performance and the potential to influence the development of rejuvenators.

Highly stable aqueous magnetic mono nanofluids of nickel ferrite (NiFe₂O₄), magnetite (Fe₃O₄), and hybrid magnetic nanofluids of NiFe₂O₄-Fe₃O₄ are synthesized through a two-step method. The structural analysis of the NiFe₂O₄ and Fe₃O₄ nanoparticles made through X-ray diffraction identifies their spinel cubic structure. The magnetic studies indicate their superparamagnetic nature, which is further confirmed through the Langevin fitting of the experimental data. The monodomain nature of nanoparticles is verified using the coupling constant, and a spherical morphology is observed using a transmission electron microscope. The surface charge of the nanoparticles is studied through zeta potential analysis. The electrical conductivity of the aqueous mono and hybrid magnetic nanofluids is measured for various concentrations and temperatures. The hybrid magnetic nanofluids show higher electrical conductivity values than those of both the mono nanofluids. For instance, NiFe₂O₄-Fe₃O₄ (1.2 vol%) hybrid nanofluid is found to have a conductivity value of 18.91 μS/cm that is 1.5 times enhanced than that of Fe₃O₄ mono nanofluid (12.87 μS/cm) and three times enhanced than that of NiFe₂O₄ (6.43 μS/cm) mono nanofluid of same volume percentage at 303 K. A Maximum enhancement of 136 % is obtained for 1.2 vol% hybrid nanofluid with respect to water at 303 K and this enhancement further increases to 196 % with the rise in temperature to 323 K. There is no theoretical model found in literature to explain the electrical conductivity of hybrid nanofluids. Maxwell, Bruggeman, Cruz, and Shen models are applied to explain the conductivity of hybrid magnetic nanofluids. Through a comparison of experimental values with theoretical values, it is found that the Shen model, if modified suitably, can explain the electrical conduction of hybrid magnetic nanofluids. Also, the electrical conduction mechanism in hybrid magnetic nanofluids is described in terms of electrophoretic charge transportation and the Brownian motion. In addition, the magneto-electrical conductivity study is performed by measuring the electrical conductivity by applying a magnetic field of various strengths. The electrical conductivity, magneto-electrical conductivity studies and an understanding of electrical conduction mechanism are highly significant for magnetically transportable electronic cooling and conducting applications of hybrid magnetic nanofluids.

In this study, we developed a laboratory-based model to analyze wettability alteration in the oil–water-rock system. The selected Surface Complexation Model (SCM), based on experimental data, is refined through sensitivity analysis and comparison with experimental measurements, including zeta potential and contact angle. Our analysis indicates that, in addition to magnesium, calcium, and sulfate ions, the adsorption of sodium and chlorine on calcite surfaces, as well as sodium adsorption on oil surfaces, significantly affects electrostatic interactions and surface potential alterations. Consequently, the complexing reactions of these ions were incorporated into the model and adjusted based on sensitivity analysis. Moreover, surface complex reactions exhibit distinct behaviors in neutral, acidic, and alkaline environments. Therefore, different reactions were considered and sensitivity analyzed for oil and rock surfaces in neutral conditions. The model’s reliability was further validated by comparing predicted and experimental zeta potentials. Additionally, disjoining pressures were computed, and contact angles were simulated, demonstrating the model’s accuracy. Key findings include the successful modification of reaction parameters to achieve accurate results across different pH levels and ion concentrations. This confirms the applicability and reliability of the developed SCM for wettability alteration analysis, further supported by stability maps that consider varying ion concentrations and pH levels.

The injection of CO₂ foam into the carbonate reservoir for enhanced oil recovery (EOR) has attracted special interest in the last decades; nevertheless, the understanding of the effect of liquid solution chemistry on foam stability at high temperatures and salinities is limited. Hence, this paper fully investigates the effect of chelating agents L-glutamic acid-N, N-diacetic acid (GLDA) pH, and hydrochloric acid (HCl) on the stability and viscosity of generated CO₂ foam for heterogeneous carbonate formation under reservoir conditions. In this paper, Duomeen TTM and Armovis VES surfactants were utilized due to their capabilities to produce viscous CO₂ foam under harsh conditions. The foamability, foam stability, and foam structure were studied at 100 °C and 1000 psi using a high-temperature and high-pressure (HPHT) foam analyzer. The measurement of CO₂ foam viscosity was determined at 100 °C, 1000 psi, and 70 % foam quality using the HPHT foam rheometer. Rheology experiments and dynamic light scattering investigated the micelle’s size or aggregation behavior of surfactants. The obtained results showed that the Duomeen TTM generated unstable foam; however, foam stability and foamability improved with the decrease in GLDA pH. Armovis VES showed excellent CO₂ foam performance, where the foam half-life time of Armovis VES systems was 240 min. The liquid drainage and bubble coarsening were delayed due to the formation of the viscoelastic liquid phase. The foamability of Armovis VES was improved as the GLDA pH decreased. Furthermore, the addition of HCl to Armovis VES solution presented the highest foamability. The outcomes of the HPHT foam analyzer and HPHT viscometer proved that as the pH of Armovis VES solution decreased, higher foamability was produced. The highest foam viscosity was obtained using the synergic effect of 0.5 wt% Duomeen TTM and 0.5 wt% Armovis VES (39 cp at 100/s). In comparison, 1 wt% Armovis VES presented the lowest foam viscosity (30 cp at 100/s). The outcomes of this research can provide insight into the effect of chemistry on CO₂ foam and extend its application in oilfield development. This work broadens the design of novel CO₂ foam formulation, leading to the improvement of sweep efficiency in CO₂-EOR methods and enhance the gas trapping in carbon storage.

The mechanical strength of conventional hydrogels is inadequate for preventing leakage in high-temperature and high-salinity reservoirs, primarily due to the increased mobility of polymer chains and the degradation of crosslinked networks. Herein, we employed the strategy of ’network nesting and layer reinforcement’ to design a hybrid multi-site crosslinked hydrogel. This approach enhances the interconnections between polymer chains and fortifies the crosslinked network. The shear rheological behavior and temperature sensitive characteristics of the profile control working fluids were evaluated based on rheological dynamics. In the high temperature (140 ℃) and high salinity (21.81 × 10⁴ mg/L) preparation environment, the effects of different components to the mechanical strength of the hydrogel were investigated under dynamic shear and uniaxial compression conditions. The incorporation of N-(hydroxymethyl)acrylamide (NMA) in the copolymerization with acrylamide (AM) resulted in an increase in the covalent cross-linking density, leading to a rise in the shear elastic modulus from 105 Pa to 238 Pa. The use of pre-gelatinized cassava starch (PGCM) as the grafting framework enhanced the bonding between the polymer chains, as evidenced by the increase in uniaxial compressive strength from 0.018 MPa to 0.081 MPa and the rise in peak strain from 55.0 % to 72.9 %. Furthermore, the synergistic effect of fumed silica (AEROSIL), which exploits mechanical coupling between inorganic nano-fillers and organic polymers, increased the compressive strength from 0.081 MPa to 0.418 MPa and raised the peak strain from 72.9 % to 81.8 %. It provides an effective approach to enhance the plugging performance of hydrogels in high temperature and high salinity reservoirs.

The continuous reduction in feature size of integrated circuits has raised stricter material removal selectivity and surface quality requirements for the chemical mechanical polishing (CMP) process of shallow trench isolation (STI). To reduce surface defects, small-sized CeO₂ abrasives are introduced into the CMP of STI. We investigated the impacts of three amino acids and their composites added to a 50 nm-sized CeO₂ dispersion (pH maintained at 5) on the polishing of silicon dioxide and silicon nitride. The promoting or inhibitory effects of amino acids first increased and then decreased with increasing concentration. When 0.02 M lysine and 0.02 M glutamic acid were added to 0.5 wt% CeO₂ dispersion, the best effect was achieved. At this time, the material removal rate (MRR) of SiO₂ and Si₃N₄ were 2993.4 Å/min and 137.2 Å/min, respectively, with surface roughness of 0.108 nm and 0.142 nm in the 5 μm × 5 μm region. This study shows that amino acids promote the MRR of SiO₂ primarily by enhancing the reactivity of Ce⁴⁺ by complexing with carboxyl groups. In contrast, amino acids inhibit the MRR of Si₃N₄ primarily by forming strong hydrogen bonds between the amino group and its surface, resulting in surface adsorption and suppressing the hydrolysis reaction. The CMP mechanisms of the three amino acids are similar, and the differences in their effects are mainly due to the varying numbers of amino and carboxyl groups they carry. The adsorption of three amino acids on SiO₂ and Si₃N₄ surfaces was simulated by Materials Studio software, and the results were consistent with the experimental results. Finally, this paper explained the mechanism of action of amino acids at the microscopic level and provided some guidance on improving the performance of CeO₂ slurry.