Water Two-phase System Research Articles

Scale reduction Transformer-based soft measurement of oil–water two-phase flow

In addressing the challenge of parameter measurement in high-water-content oil–water two-phase flow, we independently develop a dual-helix microwave sensor measurement system. Using this system, we conduct vertically upward experiments on oil–water two-phase flow and collect time-series signals characterizing microwave attenuation. Based on signal characteristics, we design a scale reduction Transformer soft measurement model (SRSM-Transformer). The time filter module effectively facilitates the aggregation and embedding of channel features with diverse physical significance. Additionally, the scale reduction temporal module models global information from a multi-resolution perspective, enabling the model to flexibly extract multi-scale feature information from fluid signals. Demonstrating pronounced superiority over existing models, our proposed model achieves recognition accuracies of 93.63% for total flow rate and 95.73% for water content. This research provides a new direction for modeling complex industrial oil–water two-phase flow systems and measuring multi-coupled key parameters.

Hydrophobic Silver-Based Coordination Polymer for the Artificial Photosynthesis of Hydrogen Peroxide in a Two-Phase System

Artificial photosynthesis is a feasible solution for obtaining hydrogen peroxide (H2O2), a clean fuel and an ecologically beneficial oxidant. The reductive synthesis of H2O2 from O2 combined with the oxidative synthesis of value-added products is particularly attractive from an economic standpoint. In a benzyl alcohol (BA)/water two-phase system, we used PhC2Ag, a hydrophobic silver-based coordination polymer, to achieve the photocatalytic generation of H2O2. PhC2Ag’s hydrophobic nature allows it to well disperse in the BA rather than consume H2O2 in water. To study the optical, photocatalytic, and photoelectrochemical properties, different precursor aqueous solution approaches have been designed to synthesize PhC2Ag (AC) and PhC2Ag (N). It is found that PhC2Ag (AC) showed apparent quantum yields of 8.62% at 420 nm. This work demonstrated that a low-pH aqueous solution and by simply decreasing the volume of the aqueous phase are beneficial for H2O2 synthesis. The applications of hydrophobic photocatalysts in the field of photocatalytic energy generation have been substantially expanded.

Lipase-Ca2+ hybrid nanobiocatalysts through interfacial protein-inorganic self-assembly in deep-eutectic solvents (DES)/water two-phase system for biodiesel production

The production of biodiesel catalyzed by lipase has the advantages of simple process, low energy consumption, and low wastewater treatment requirements. However, low activity, poor stability, and difficulty in recycling still limit the application of lipase in production of biodiesel. Herein, a novel lipase hybrid biocatalyst with superior catalytic activity and stability (lipase from Aspergillus oryzae CJLU-3, AOCL@CaP in DES) was developed by dual activation of Ca2+ and interfacial effect of deep-eutectic solvents (DES)/water two-phase system. AOCL@CaP in DES exhibited significantly enhanced enzymatic activity with a Kcat/Km value of 692 s−1 mM−1 and excellent thermostability, tolerance to chemical denaturants, substrate selectivity, and reusability compared with free lipase. Recovery activity of the prepared hybrid biocatalyst in pure water system (AOCL@CaP) and AOCL@CaP in DES was 195% and 250% using p-NPL as substrate, respectively. AOCL@CaP in DES exhibited about 253% of the original activity after 100 days of storage, while free AOCL, AOCL@CaP almost completely lost activity. The FAME content in product biodiesel catalyzed from soybean oil by AOCL@CaP was only 60%, However, the FAME content catalyzed by AOCL@CaP in DES reached 87%, and could be maintained at 50% even after 10 cycles.

A two-dimensional study on the impact of pore space connectivity on the immiscible two-phase flow in a water-wet, water–oil system under steady state conditions

Immiscible displacements in porous media are unquestionably of great significance in numerous natural and industrial processes. It has been well established and accepted that in addition to the immiscible fluid properties, the morphology of the porous medium also plays a significant role in the final volumetric throughput of a particular fluid. Topological features of the porous medium have been found to exert a strong influence on the hydrodynamic behaviour of single and two-phase flows as they express a measure of pore space and consequently flow path connectivity and availability. The current study investigates the effect of the pore space connectivity, expressed through the Euler characteristic, on the hydrodynamic behaviour of a water-wet, oil–water two-phase system at steady state. Two-dimensional simulations are conducted in artificially generated porous media with constant diameter circular solid grains using a multi-relaxation time lattice-Boltzmann model. It is shown that topological features of the porous medium can significantly affect the macro-scale capillary pressure and relative permeability curves for drainage and imbibition but in different ways. It is also demonstrated that pore space connectivity has a strong influence on the fluid phase distribution and fragmentation patterns in the porous structure depending on the displacement process.

The migration law of magnesium ions during freezing and melting processes

To explore the migration law of magnesium ions (Mg2+) during freezing and melting processes, laboratory simulation experiments involving freezing and melting were carried out to investigate the influence of ice thickness, freezing temperature, initial concentration, and initial pH on the distribution of Mg2+ in the ice-water system. The distribution coefficient “K” (the ratio of the Mg2+ concentration in the ice layer to the Mg2+ concentration in the water layer under ice) was used to characterize the migration ability of Mg2+. The results showed that during the freezing process, the concentration distribution of Mg2+ in the ice and water two-phase system was as follows: ice layer < water before freezing < water layer under ice; in other words, it migrated from ice layer to the water layer under ice. “K” decreased with increasing ice thickness, freezing temperature, initial concentration, and initial pH; the higher the ice thickness, freezing temperature, initial concentration, and initial pH were, the higher the migration efficiency of Mg2+ into the water layer under ice was. During the melting process, Mg2+ was released in large amounts (50–60%) at the initial stage (0–25%) and in small amounts (25–100%) uniformly in the middle and later periods. According to the change of Mg2+ concentration in ice melt water, an exponential model was established to predict Mg2+ concentration in ice melt period. The migration law of Mg2+during the freezing and melting process was explained by using first principles.Graphical abstract

Long-chain alkanol–alkyl carboxylic acid-based low-viscosity hydrophobic deep eutectic solvents for one-pot extraction of anthraquinones from Rhei Radix et Rhizoma

Natural long-chain alkanol and alkyl carboxylic acid were used to prepare novel hydrophobic deep eutectic solvents (HDESs). These HDESs are liquid at room temperature and have low viscosity (<12.26 mPa‧s), low polarity (lower than that of methanol, ChCl-based deep eutectic solvents and other reported HDESs), and low density (<0.928 g/mL). A simple one-pot method based on a novel HDES–water two-phase extraction system was constructed for the extraction of weak-polarity bioactive components, anthraquinones, from Rhei Radix et Rhizoma. This HDES-based new extraction method does not consume hazardous organic solvents and can obtain a total anthraquinone yield of 21.52 mg/g, which is close to that obtained by the Chinese pharmacopoeia method (21.22 mg/g) and considerably higher than those by other reported HDESs-based extraction methods (14.20–20.09 mg/g, p < 0.01). The high extraction yield can be mainly attributed to the severe destruction of the RRR cell walls by the extraction system and the excellent dissolving ability of novel HDESs for anthraquinones.

Acid-Catalytic Oxidation of Thiophene by Hydrogen Peroxide in n-Octane–Water System

The effect of the reaction time and temperature, composition and concentration of the oxidizing mixture on the degree of thiophene conversion in the n-octane–water two-phase system was studied. The oxidative activity of peroxyacids generated from hydrogen peroxide and acids (trifluoroacetic, formic, nitrous) changes in the series СF3COOOH > HCOOOH > HOONO. The addition of cetyl(trimethyl)ammonium bromide inhibit the oxidation of thiophene.

QSPR Modeling of Liquid-liquid Equilibria in Two-phase Systems of Water and Ionic Liquid.

The increasing application of new ionic liquids (IL) creates the need of liquid-liquid equilibria data for both miscible and quasi-immiscible systems. In this study, equilibrium concentrations at different temperatures for ionic liquid+water two-phase systems were modeled using a Quantitative-Structure-Property Relationship (QSPR) method. Data on equilibrium concentrations were taken from the ILThermo Ionic Liquids database, curated and used to make models that predict the weight fraction of water in ionic liquid rich phase and ionic liquid in the aqueous phase as two separate properties. The major modeling challenge stems from the fact that each single IL is characterized by several data points, since equilibrium concentrations are temperature dependent. Thus, new approaches for the detection of potential data point outliers, testing set selection, and quality prediction have been developed. Training set comprised equilibrium concentration data for 67 and 68 ILs in case of water in IL and IL in water modeling, respectively. SiRMS, MOLMAPS, Rcdk and Chemaxon descriptors were used to build Random Forest models for both properties. Models were subjected to the Y-scrambling test for robustness assessment. The best models have also been validated using an external test set that is not part of the ILThermo database. A two-phase equilibrium diagram for one of the external test set IL is presented for better visualization of the results and potential derivation of tie lines.

Effect of CO2 injection on interfacial tension of oil-formation water system under high temperature and pressure

The interfacial interaction between CO2 and oil and water is one of the important factors affecting the effect of CO2 enhanced oil recovery. Taking dead oil in Zhoucheng Oilfield as an example, the variation of interfacial tension between crude oil-carbonated water two-phase system and oil-formation water two-phase system was studied by pendant drop method. The influence of different CO2 saturation on the equilibrium interfacial tension of oil-formation water system and changes of equilibrium interfacial tension between crude oil-carbonated water system and crude oil-formation water system were analyzed. Moreover, previous studies did not reflect the experimental phenomena of extracting light hydrocarbons from oil droplets by CO2 through gas-water interface. This paper provides experimental research and analysis for this experimental phenomenon. The results show that the equilibrium interfacial tension of crude oil-carbonated water system decreases with the increase of pressure, and the dissolution and diffusion of the system becomes more and more obvious with the increase of pressure. The medium exchange occurs between oil and carbonated water, and the phenomenon of partial miscibility occurs. There is a threshold pressure value between crude oil and formation water with different CO2 saturation. Each group of samples has its threshold pressure and optimum CO2 injection rate. It’s not that the more CO2 injection, the better oil displacement effect. This research provides a reference for us to save the cost of CO2 flooding.

Experimental and Thermodynamic Modeling of Quaternary Aqueous Two-Phase System of Poly Ethylene Glycol, Sodium Tartrate, Water and Penicillin G

In present study, the liquid–liquid equilibrium of the quaternary system of polyethylene glycol (PEG) (with molar masses of 1000, 2000, 6000, and 8000 g·mol−1), sodium tartrate salt, Penicillin G and water at 298 K were investigated. The partitioning of Penicillin G between two aqueous phases was also reported. The extended non random two liquid (NRTL) and extended Universal Quasi Chemical (UNIQUAC) models were used to correlate the experimental equilibrium data. The parameters of these activity coefficient models were optimized for the investigated systems. The results show that the polymer molar mass has a dominant effect on the partition coefficient of Penicillin G. Also, results of both thermodynamic models were very satisfactory and satisfactory predicted the equilibrium concentrations of the components in ATPS. Comparison of the absolute average deviation of the two models shows that the extended UNIQUAC model was superior to the extended NRTL model for correlation and interpolation of phase equilibrium data.

Oil-in-Water Two-Phase Flow Pattern Identification From Experimental Snapshots Using Convolutional Neural Network

The flow pattern is one of the most significant parameters in modeling the oil–water two-phase system. How to extract efficient and objective features to precisely identify the oil–water two-phase flow patterns is still a significant issue. Inspired by the deep learning hierarchically feature extraction way, we, in this paper, employ convolutional neural networks (CNNs) to identify oil–water two-phase flow patterns. First, we carry out oil–water two-phase flow experiment and collect different oil–water flow pattern images. Then, we propose an image segment algorithm based on the minimum gray level to obtain the interest region that reflects the flow pattern characteristics. Finally, we employ three frequently used CNNs, LeNet-5, AlexNet, and VGG-16 net, to extract the image features and identify typical oil–water two-phase flow patterns. The results show that networks with more deep structures preserve relatively high flow pattern recognition accuracy. This paper provides a novel application of the deep learning method for the oil–water two-phase flow identification.

Kinetic Study of 5-Hydroxymethylfurfural Synthesis from Fructose in High Pressure CO2–Water Two-Phase System

In this work, synthesis of 5-hydroxymethylfurfural (5-HMF) from lignocellulosic biomass derived hexoses, fructose in our case, was developed in two-phase supercritical CO2–water systems. Conditions of reactions were above 10 MPa and 120 °C, i.e., the two-phase reacting mixture can be regarded as a subcritical water–supercritical CO2 system. From kinetic experiments and their modeling, it was possible to assess the effect of CO2 as a potential reversible acid catalyst. The kinetic model developed in this study considers also the catalytic contribution of acid byproducts, as proton providers, for the reaction of dehydration of fructose into 5-HMF. Selectivity toward 5-HMF was improved with increasing pressure to reach a maximum of 80 mol % after 3 h of reaction at 150 °C and under 25 MPa of CO2, as only 60% was achieved without the use of pressurized CO2.

EXTRACTION AND ELECTROPHORETIC DETERMINATION OF VANILLIN IN AQUEOUS SOLUTIONS AND ENERGY DRINKS WITH POLYMERS BASED ON N-VINILFORMAMIDE

The problem of development of new ways of extraction of vanillin from aqueous mediums of various genesis for the analysis and determination of an anolyte under production of foodstuff and energy drinks was actualized. Two-phase water systems on the basis of water-soluble polymers most fully satisfy requirements for extractive systems. Regularities of interphase distribution of vanillin in a water-salt extraction systems on the basis of poly-N-vinylformamide and N-vinilformamide copolymer with N-vinylimidazole are established. The rate of formation of the two-phase system "water-soluble polymer - water-salt solution of vanillin" is significantly influenced by the molecular mass of the extractant: with increasing intrinsic viscosity, the amount of polymer necessary to form a heterogeneous system in the presence of a salting out agent decreases. Influence of ratio of water and organic phases on effectiveness of extraction of vanillin, including in the presence of a caffeine is studied. Effectiveness of use of extraction systems on the basis of the synthesized copolymers for extraction and elektroforetic determination of vanillin and caffeine is established. During the research some conditions of electrophoretic detecting of vanillin and caffeine were optimized: structure of a buffered solution, type and the concentration of a mitsello adjustable influence the dividing ability of a buffered solution. Distribution coefficients and extent of extraction of vanillin are calculated. Schemes of formation of associates in systems vanillin-polymer are offered. The maximal values of extraction characteristics of vanillin in systems with copolymer are lower, than at extraction in systems with poly-N - vinylformamide. It was established that introduction to system of a component with bonds of N-vinylimidazole leads to formation of intramolecular bonds between OH - groups of N-vinylimidazole and "pyridinic" N-atoms of an imidazolny cycle. The way of electrophoretic selection determination of vanillin and caffeine in energy drinks with preliminary extraction of target components with the use of polymers is developed. Forcitation:Mokshina N.Ya., Pakhomova O.A., Shatalov G.V., Lavlinskaya M.S. Extraction and electrophoretic determination of vanillin in aqueous solutions and energy drinks with polymers based on N-vinilformamide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 13-19.

Liquid-Liquid Equilibrium Data, Viscosities, Densities, Conductivities, and Refractive Indexes of Poly (vinyl pyrrolidone)+ tri-sodium Citrate + Urea Aqueous Two-Phase Systems at Different pH

Abstract The present study investigated liquid-liquid equilibria of polyvinylpyrrolidone (PVP) K30 + tri-sodium citrate + urea (5% and 10% mass) aqueous two-phase systems at 25°C and pH values of 6.2, 7.4, and 10.0. Results showed that the binodal was displaced toward higher concentrations as the urea concentration increased. The effect of pH, polymer/salt (w/w) ratio, urea concentration, tie line length, and slope of tie line on the partition behavior of urea was examined. The viscosity, density, electrical conductivity, and refractive index of PVP (K30) + tri-sodium citrate + urea + water two-phase systems were measured versus pH value. The relation between tie line length and the density and viscosity of the aqueous two-phase systems was also examined.

Effect of pH on Properties of Poly(Vinyl Pyrrolidone) + Tri-Sodium Citrate + Guanidine Hydrochloride Aqueous Two-Phase Systems

The experimental results for liquid–liquid equilibrium of poly(vinyl pyrrolidone) (K30) + tri-sodium citrate + guanidine hydrochloride (5 and 10 w/w%) aqueous two-phase system at 25°C and different pH values (6.2, 7.4, and 10.0) were studied. The partition behavior of guanidine hydrochloride is known to be a function of several factors. Some of them such as guanidine hydrochloride concentration, pH, polymer/salt ratio (w/w), size, and slant of the tie-lines (STLs) are investigated in this study. At higher guanidine hydrochloride concentrations, the binodal was observed to displace. The behavior of the tie-line size (TLS) seems to be somehow different from the influence of the polymeric phase. The increase of GuHCl concentration decreased the STLs, but the slant and size of the equilibrium tie-lines increased with the pH of the two-phase system. The viscosity (η), density (ρ), electrical conductivity (k), and refractive index (nD) of the poly(vinyl pyrrolidone) (K30) + tri-sodium citrate + guanidine hydrochloride + water two-phase systems versus pH were investigated. It was observed that the viscosity and density of the aqueous two-phase system is influenced by the TLS. The density changes between the phases (Δρ) and viscosity changes of the phases (Δη) increased with the increase of the TLS. It was found that linear relations exist between the TLS and the interphase density and viscosity changes.

Numerical simulation study of fracturing wells for shale gas with gas–water two-phase flow system under desorption and diffusion conditions

Hydraulic fracturing is an essential technology in developing shale gas reservoirs, not to mention, accurate prediction of productivity in fractured shale gas wells is the foundation of an efficient development in shale gas reservoirs. This paper establishes a gas–water two-phase flow percolation mathematical model by a determined numerical simulation and calculation method under desorption and diffusion conditions. By means of simulating for a post-frac performance of the shale gas reservoir, this paper devotes to a quantitative analysis the impact of fracture parameters, physical parameters, and desorption–diffusion parameters. The outcome of this research indicates that hydraulic fracturing can improve single well production and it's an effective measure in the development of shale gas. The conductivity of hydraulic fractures and the permeability of natural fractures are the main influences on shale gas production. The higher these factors are, the higher the gas and water productions are. In comparison, the matrix permeability and diffusion coefficients have minimal influences on production.

Mixture temperature prediction of waxy oil–water two-phase system flowing near wax appearance temperature

Temperature sensitivity of waxy crude oils makes it difficult to study their flow behaviour in the presence of water especially near their wax appearance temperature (WAT). In this study a method was proposed and implemented to mitigate such difficulties which was applied in predicting mixture temperatures (Tm) of a typical Malaysian waxy crude oil and water flow in a horizontal pipe. To this end, two analytical models were derived firstly from calorimetry equation which based on developed two correlations for defining crude oil heat capacity actualized from the existed specific heat capacities of crude oils. The models were then applied for a set of experiments to reach the defined three predetermined Tm (26°C, 28°C and 30°C). The comparison between the predicted mixture temperatures (Tm,1 and Tm,2) from the two models and the experimental results displayed acceptable absolute average errors (0.80%, 0.62%, 0.53% for model 1; 0.74%, 0.54%, 0.52% for model 2). Moreover, the average errors for both models are in the range of standard error limits (±0.75%) according to ASTM E230. Conclusively, the proposed model showed the ease of obtaining mixture temperatures close to WAT as predetermined with accuracy of ±0.5°C approximately for over 84% of the examined cases. The method is seen as a practical reference point to further study the flow behaviour of waxy crudes in oil–water two-phase flow system near sensitive temperatures.

Novel method for separation and screening of lubricant-degrading microorganisms and bacterial biodegradation

With the rapid increase of lubricant consumption, oil contamination becomes more serious. Biotreatment is an important method to remove oil contamination with some advantages. In this study, acclimatized oil-contaminated soil and used lubricating oil were sampled to isolate lubricant-degrading strains by several methods. 51 isolates were obtained and 24-well plates were employed to assess bacterial potential in high-throughput screening. The method was noted for the prominence of oil–water two-phase system with saving chemicals, shortening cycles and lessening workloads. In order to decrease inaccuracy, subculture and resting cells were inoculated into mineral salt medium with 200μl oil in well plates for the cultivation at 37°C for 5 and 7days, and the biodegradation potential was characterized by the changes of oil film and cell density. With appropriate evaluation by shaking flask tests, 5 isolates were retained for their potentials with the maximum biodegradation from 1500 to 2200mg·L−1 and identified as Acidovorax citrulli, Pseudomonas balearica, Acinetobacter johnsonii (two isolates with different biodegradation potentials) and Acidovorax avenae using 16S rRNA sequencing analysis. Also, lipase activity was determined using indicator titration and p-nitrophenyl palmitate (p-NPP) methods. The results indicated that only p-NPP was successful to test lipase activity with the range of 1.93–6.29U·ml−1. Although these five strains could degrade 1000mg·L−1 lubricating oil in 158–168h, there existed distinct difference in enzyme activity, which demonstrates that lipase activity could not be used as the criterion to evaluate microbial biodegradation potential for petroleum hydrocarbons.

Cloudy behavior and equilibrium phase behavior of triblock copolymer L64 + salt + water two-phase systems

The cloud point (CP) values of aqueous solutions of the triblock copolymer L64 were determined in the absence and presence of five salting-out salts (K2SO4, Na2SO4, (NH4)2SO4, K2CO3, K2HPO4) at different concentrations. All the five salts could decrease the CP values and form aqueous two phase systems (ATPSs) with L64. A notable phase inversion phenomenon occurred with the increasing salt concentrations and the phase inversion points were found. The salt-rich phase transferred from the top phase to the bottom phase because of the change of density. Liquid–liquid equilibrium (LLE) data of these ATPSs were measured at 45 °C, respectively. The consistency of the tie-lines was verified by using the empirical equations from the Othmer-Tobias and Bancroft correlation. The effects on the cloudy behavior and phase separation depended on the salting-out ability. The results showed that the salting-out ability of the cations followed the order: Na+ > K+ > NH4+; the anions followed the order: HPO42− > SO42− > CO32−. It could be concluded that using the Gibbs free energy of hydration of the ions (ΔGHyd) to estimate salting-out ability was not suitable for all of the ATPSs.

Characterization of the physicochemical properties of phospholipid vesicles prepared in CO2/water systems at high pressure.

Phospholipid vesicles were prepared by the nonsolvent method using high-pressure CO2/water systems. The membrane properties of vesicles prepared at different pressures and temperatures were mainly characterized based on analysis of the membrane fluidity and membrane polarity, using the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene and 6-dodecanoyl-N,N-dimethyl-2-naphthylamine, respectively. The CO2(liquid)/water(liquid) and the CO2(supercritical)/water(liquid) two-phase (heterogeneous) systems resulted in the formation of vesicles with high yield (ca. 85%-88%). The membrane fluidity and polarity of the vesicles were similar to those of liposomes prepared by the conventional method. It is suggested that high-pressure CO2 can be used to form an appropriate hydrophobic-hydrophilic interface where phospholipid molecules as a self-assembled membrane.