Pure Liquid Research Articles

An amino acid ionic liquid-based biphasic solvent with low viscosity, small rich-phase volume, and high CO2 loading rate for efficient CO2 capture

In order to achieve efficient CO2 capture, a novel biphasic solvent based on diethylenetriamine serine ionic liquid/polyethylene glycol dimethyl ether/water ([DETA][SER]/NHD/H2O) was developed. This study achieved low viscosity by weakening the hydrogen bonding and van der Waals interactions within the pure ionic liquid (IL) by adding NHD and H2O to [DETA][SER]. Additionally, due to the low polarity and fewer hydrogen bonds formed by NHD, it is separated. The formation of a tight hydrogen bond network in the rich-phase after the reaction enables the enrichment of the product. Based on this, the optimal mass ratio of [DETA][SER]/NHD/H2O is determined to be 20 wt%/40 wt%/40 wt%. The viscosity of this solvent is 7.82 mPa·s, with a total absorption load of 1.26 mol·mol−1 IL, where the rich-phase load accounts for 99 % of the total load and occupies only 37 % of the volume. The mechanism of CO2 capture was investigated using 13C NMR, revealing the formation of zwitterions from the reaction of the primary amines on [DETA]+ and [SER]− with CO2. Subsequently, proton transfer and hydrolysis of the carbamate esters were observed. Notably, NHD was found to promote phase separation without participating in chemical reactions. These findings demonstrate the potential of this biphasic solvent system as a high-capacity solution for CO2 capture.

Study on the interaction properties of ionic liquid mixtures with a common anion: A combination of spectral and theoretical study

Ionic liquid mixtures have garnered significant attention due to their promising applications. Despite this interest, there remains a limited understanding of these mixtures, particularly regarding their microstructure. A comprehensive understanding of their microstructural characteristics and properties is essential for harnessing the full potential of ionic liquid mixtures. In this work, the structural properties and interactions were investigated within mixtures of two specific ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4C1im][NTf2]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4C1pyrr][NTf2]). Employing a combination of experimental and theoretical methods, the following conclusions were obtained: (1) The cis- and trans-configurations of [NTf2]− coexist in pure ionic liquids and their mixtures; (2) The primary interaction site of [C4C1im]+ and [C4C1pyrr]+ are C2−H and H on the methylene group attached to the N atom, respectively. It mainly interacts with O atoms in [NTf2]− anions through hydrogen bond interactions; (3) The introduction of [C4C1pyrr][NTf2] weakens the hydrogen bonding interactions within the ionic liquid mixtures.

Application of the CL&P-Pol polarizable force field in the determination of the excess chemical potential of thiophene within the [C4mim] [BF4, Cl, Br, CH3COO] ionic liquids

The combustion of fossil fuels is an important source of air pollution due to the presence of sulfur-based compounds. In this regard, a reliable atomistic forcefield is required in order to provide insights on solute-solvent interactions, and in designing high aromatic sulfur extracting solvents. In the present work, the excess chemical potentials of thiophene within four 1-butyl-3-methylimidazolium-based ionic liquids were evaluated through the free energy perturbation with replica exchange molecular dynamics methodology by using the CL&Pol polarizable force fields based on Drude oscillators. First, in order to validate the accuracy of the polarizable force fields, a series of thermodynamic properties of pure ionic liquids such as diffusion coefficient, liquid density, dielectric constant, and heat of vaporization were computed using the CL&Pol force field and compared against experimental values. The results from the calculated thiophene excess chemical potential values, indicated that the [C4mim][CH3COO] ionic liquid presents the more favorable excess chemical potential (higher solubility) with respect to the thiophene molecule at both 300 K and 343 K in comparison to the other ionic liquids studied. The structural analysis revealed that the ionic liquid anion interacts more closely and with well-defined RDF peaks with the thiophene molecule, the larger anions present higher surrounding particle densities with the thiophene molecules (solvation shell), while the monoatomic anions interact preferentially with the hydrogens close to the sulfur thiophene atom; In contrast no marked solvation layers were observed with the ionic liquid cations.

Dielectric Response of Different Alcohols in Water-Rich Binary Mixtures from THz Ellipsometry.

We report a study on the hydrogen bonding mechanisms of three aliphatic alcohols (2-propanol, methanol, and ethanol) and one diol (ethylene glycol) in water solution using a time-domain ellipsometer in the THz region. The dielectric response of the pure liquids is nicely modeled by the generalized Debye-Lorentz equation. For binary mixtures, we analyze the data using a modified effective Debye model, which considers H-bond rupture and reformation dynamics and the motion of the alkyl chains and of the OH groups. We focus on the properties of the water-rich region, finding anomalous behavior in the absorption properties at very low solute molar concentrations. These results, first observed in the THz region, are in line with previous findings from different experiments and can be explained by taking into account the amphiphilic nature of the alcohol molecules.

Effects of vibrational flow on nanofluid flow behavior under different temperature boundary conditions

A comparative study was conducted using a well-validated computational fluid dynamics (CFD) model to investigate the effects on heat transfer. The study focused on forced convection internal flow of both base fluid and nanofluid, subjecting them to different boundary conditions. Vibration was applied in the transverse direction to the flow. The simulations were performed with varying Reynolds numbers, volume fractions, vibration frequencies, and amplitudes. In order to improve the predictive capabilities of the computational fluid dynamics (CFD) model for single-phase flow systems, rheological properties dependent on temperature were incorporated. The introduction of transverse vibrations swiftly disrupted the thermal boundary layer, resulting in an axial temperature increase for low Reynolds number flows. Consequently, under constant wall temperature conditions, this led to heightened heat transfer rates. The observed enhancement in heat transfer rate, achieved through variations in volume fraction and particle diameter, aligned with typical behavior exhibited by nanofluids under steady-state flow. However, under vibrational conditions, the heat transfer enhancement surpassed that of the pure liquid significantly. As frequency levels rose, the impact of vibrations diminished, while changes in amplitude exerted a more pronounced influence. The most substantial increase, approximately 540%, was witnessed under vibrational flow conditions compared to steady-state flow. The ratio of the heat transfer coefficient was about 28% higher when the flow was subjected to uniform heat flux but under unsteady-state conditions. However, there was not much growth in the outlet temperature observed.

PREPARATION AND CHARACTERIZATION OF PERFLUOROETHYLSUBSTITUTED ALKYLAMMONIUM OLIGOFLUOROPHOSPHATES

Mono-, di-, triperfluoroethyl substituted fluorophosphate anions are building blocks in the molecular design of salts with onium cations, and are used to increase hydrophobicity, modify surfactant properties and electrical conductivity. The work proposes methods for the synthesis of superacid H+[PF3(C2F5)3]- by the reaction of tri(pentafluoroethyl)difluorophosphorane with a solution of hydrofluoric acid, as well as superacids H+[PF4(C2F5)2]- and H+[PF5C2F5]- by step-by-step removal of the pentafluoroethyl substituent by hydrolysis with subsequent treatment with HF solution. Ionic compounds were synthesized by metathesis of anions at 0 °C from the corresponding quaternary ammonium chloride based on the obtained superacids. The article presents NR4FAP-class ionic compounds with the tributylmethylammonium (TBMA) cation of the general formula [(C4H9)3NCH3]+[PF6-n(C2F5)n]-, where n = 1, 2, 3. The square bipyramidal structure of the three studied anions was confirmed by nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) data. The study shows, the synthesized compounds are characterized by extremely low vapor pressure up to 300 °C, a wide range of the liquid state with a width of up to 310 K by the methods of differential scanning calorimetry (DSC) and synchronous thermal analysis (STA). Melting temperatures and enthalpies were determined. The TBMA salts belong to ionic liquids (IL's), including one type liquid at room temperature (RT-IL). The general patterns of compounds decomposition were analyzed by the analysis of evolved gases (STA-EGA); it was shown that in all cases, the decomposition of the studied ionic liquids begins with the destruction of the anion. The electrical resistance of a pure ionic liquid at room temperature was studied. The described characteristics of perfluoroethylsubstituted alkyl ammonium oligofluorophosphates open up prospects for their use as electro conducting and antistatic additives for petrochemicals, fuels and polymers. For citation: Mokrushin I.G., Pinegina O.A., Krasnovskikh M.P., Dmitriev M.V., Markin I.V., Kozen A.L. Preparation and characterization of perfluoroethylsubstituted alkylammonium oligofluorophosphates. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 54-61. DOI: 10.6060/ivkkt.20246705.6916.

Updates to Protex for Simulating Proton Transfers in an Ionic Liquid.

The Python-based program Protex was initially developed for simulating proton transfers in a pure protic ionic liquid via polarizable molecular dynamics simulations. This method employs a single topology approach wherein deprotonated species retain a dummy atom, which is transformed into a real hydrogen atom during the protonation process. In this work, we extended Protex to include more intricate systems and to facilitate the simulation of the Grotthuss mechanism to enhance alignment with the empirical findings. The handling of proton transfer events within Protex was further refined for increased flexibility. In the original model, each deprotonated molecule contained a single dummy atom connected to the hydrogen acceptor atom. This model posed limitations for molecules with multiple atoms that could undergo protonation. To mitigate this issue, Protex was extended to execute a proton transfer when one of these potential atoms was within a suitable proximity for the transfer event. For the purpose of maintaining simplicity, Protex continues to utilize only a single dummy atom per deprotonated molecule. Another new feature pertains to the determination of the eligibility for a proton transfer event. A range of acceptable distances can now be defined within which the transfer probability is gradually turned off. These modifications allow for a more nuanced approach to simulating proton transfer events, offering greater accuracy and control of the modeling process.

Estimating ionic conductivity of ionic liquids: Nernst–Einstein and Einstein formalisms

Ionic conductivity plays an important role towards the application of ionic liquids as electrolytes in next-generation batteries and electrochemical processes and is often estimated using the Nernst–Einstein formalism in molecular simulation-based studies. The Nernst–Einstein formalism is useful for dilute systems where ions do not interact with each other, restricting its applicability to dilute solutions. However, this approximation fails in concentrated solutions where ion interactions become significant, which is usually encountered for pure ionic liquids. These ion-ion correlations can dramatically affect ionic conductivity predictions in comparison to that computed under the Nernst–Einstein formalism. This study highlights the challenges associated with calculating ionic conductivity using Einstein formalism and subsequently provides a workflow for such calculations. It has been found that a minimum trajectory length of 60 ns is required to achieve converged results for Einstein ionic conductivity. Guidance is also given to reduce the computational resource requirements for Einstein conductivity determination. This simplification will enable researchers to estimate Einstein conductivity in ionic liquids more efficiently.

Divinyl polysiloxane modified polyacrylate for promoting the directional migration of disperse dyes in digital jet dyeing of polyester fabric without washing

Future developments in the printing and dyeing industry will involve greenisation and personalisation. Less/no water digital technology has drawn much attention over traditional printing and dyeing for reducing carbon and emissions. Based on the solubility parameter difference between disperse dyes and monomers, divinyl polysiloxane modified polyacrylate (PSMA) with the directional migration effect for disperse dyes was prepared herein via mini-emulsion polymerisation. PSMA was used as wash-free polymer additive in the digital jet dyeing of polyester fabrics with disperse dyes, which yielded wash-free dyed fabrics with high color yield and color fastness. The results showed that PSMA achieved the optimum overall performance at a molar ratio of octamethylcyclotetrasiloxane to 1,3-divinyltetramethyldisiloxane 44:1 and divinyl polysiloxane dosage of 4 wt%. PSMA had the best tensile properties, good flexibility, certain hydrophobicity and high directional migration of disperse dyes. When the PSMA dosage was 9 wt% in the wash-free ink, the front and back color yield of the wash-free dyed fabric were 18.23 and 13.56, respectively. Compared with the fabric dyed with pure liquid disperse red, the front color yield of the wash-free dyed fabric increased by about 35.2 % and the back color yield had a little change. Its color fastness to dry/wet rubbing were improved from grade 3 to 4 and from grade 2–3 to 3, respectively. The handle of the wash-free dyed fabric basically maintained the level of original fabric.

Modeling and measurement of density and viscosity of ethyl Lactate + 1-alkanol mixtures

In the current paper, the aim is to investigate the characteristics and relationships of liquid mixtures containing ethyl lactate and 1-Alkanols (C4–C7), which include 1-butanol, 1-pentanol, 1-hexanol, and 1-heptanol. To accomplish this, excess molar volumes and the deviation in viscosity were determined by utilizing experimental density and viscosity measurements at different temperatures and a pressure of 0.1 MPa. Our findings revealed that for solutions containing ethyl lactate and 1-butanol or 1-pentanol, positive values were observed when the mole fractions were higher in alcohols and lower in lactate. However, as the mole fractions shifted towards higher levels of lactate, the excess molar volumes became negative. On the contrary, when examining binary solutions of ethyl lactate with 1-hexanol and 1-heptanol, positive values for the excess molar volumes were found. The PC-SAFT model was used to simulate the density of pure fluids and liquid mixtures, resulting in a maximum deviation of 1.17 % for ethyl lactate and 1-hexanol solutions. Our analysis revealed that PC-SAFT is capable of accurately predicting and correlating the density of both pure liquids and solutions.

Evaporation from a cylindrical cavity: effect of gravity on the vapour cloud

We examine the vapour cloud of a pure liquid evaporating from a millimetric cylindrical well/cavity/aperture. This is accomplished by injecting the liquid up a vertical pipe towards its outlet onto a horizontal substrate. The injection is halted before the liquid surpasses the substrate level. The resulting final state is a meniscus at or near the pipe's end. The analysis is realised by vapour interferometry (side view over the substrate) closely intertwined with simulations (including Stefan flow), which also help to fill up certain gaps in the measurements and provide computed evaporation rates. Comparison with experiment is facilitated by converting the computed vapour clouds into interferometric images, especially helpful when an inverse (Abel-type) conversion is difficult. Experiments are conducted in both microgravity (via parabolic flights) and ground conditions, thus enabling direct assessment of the role of gravity. The contrast is accentuated by a working liquid with heavy vapour (refrigerant HFE-7100), when instead of being flattened on ground the vapour cloud assumes a roughly hemispherical shape in microgravity. Furthermore, a non-trivial vapour-cloud response to the flight ${\rm g}$ -jitter (residual gravity oscillations) is unveiled, ${\rm g}$ -jitter vibrations posing a challenge for interferometry itself. A number of undesired but curious side issues are revealed. One concerns vapour formed deep inside the pipe during rapid injection and subsequently ejected into the field of view, which is detected experimentally and quantified in terms of vapour Taylor dispersion in the pipe. Others are an injection volume anomaly and parasitic postinjection specifically observed in microgravity conditions.

Solubility of seven amino acids in two acetate ionic liquids from 298.15 K to 328.15 K

The number of studies on the solubilities of amino acids in pure ionic liquids is currently very scarce. Focusing on fundamental studies for the recovery of added-value compounds from fisheries and aquaculture discards, in this work the solubility of several amino acids in acetate ionic liquids and their mixtures with water were determined at temperatures ranging from 298.15 K to 328.15 K and atmospheric pressure. Sharing the acetate anion, solubilities were higher in the ionic liquid with 1-ethyl-3-methylimidazolium than with 1-hexyl-3-methylimidazolium cation. Increasing temperatures resulted in enhanced solubilisation. Solubilities in the ionic liquids ranked thus: Pro > OH-Pro > Lys·HCl > Ala > Gly > Cys, with an intermediate position of Arg (the amino acid most influenced by the hydrophobic environment and temperature). In the case of the mixtures with water, the ranking was Pro > Lys·HCl > Ala > Arg > OH-Pro > Gly > Cys. The van't Hoff equation adequately correlated experimental solubilities in the range of temperatures studied, and the process of dissolution was found endothermic and entropy-driven in all the cases. The ionic liquid 1-ethyl-3-methylimidazolium should be considered for the target application and the water content a design variable to analyse.

Effect of Surfactants on the Splashing Dynamics of Drops Impacting Smooth Substrates.

We present the results of a systematic study elucidating the role that dynamic surface tension has on the spreading and splashing dynamics of surfactant-laden droplets during the impact on hydrophobic substrates. Using four different surfactants at various concentrations, we generated a range of solutions whose dynamic surface tension were characterized to submillisecond timescales using maximum bubble-pressure tensiometry. Impact dynamics of these solutions were observed by high-speed imaging with subsequent quantitative image processing to determine the impact parameters (droplet size and speed) and dynamic wetting properties (dynamic contact angle). Droplets were slowly formed by dripping to allow the surfactants to achieve equilibrium at the free surface prior to impact. Our results indicate that while only the fastest surfactants appreciably affect the maximum spreading diameter, the droplet morphology during the initial stages of spreading is different to water for all surfactant solutions studied. Moreover, we show that surfactant-laden droplets splash more easily than pure liquid (water). Based on the association of the splashing ratio to our tensiometry measurements, we are able to predict the effective surface tension acting during splashing. These results suggest that droplet splashing characteristics are primarily defined by the stretching of the equilibrated droplet free surface.

Effect of gas content on cavitation nuclei

Cavitation inception originates from nuclei in a liquid. This paper proposes a Gibbs free energy approach that provides a smooth transition from homogeneous to heterogeneous nucleation when gas is present. The impact of gas content on nucleation is explored. It is found that the gas content stabilises nuclei, a phenomenon not present in pure liquid–vapour systems. This reduces the energy barrier over that required to nucleate a vapour bubble. Different gas saturation levels are studied. Gas content can significantly reduce the energy barrier required for nucleation, and under certain circumstances eliminate it. An analytic solution for the critical radius and activation energy is obtained that accounts for gas content. The classical Blake radius is recovered as a limiting case. The hysteresis between incipience and desinence is explained using the asymmetry observed in the critical radii. The solution is used to obtain the initial bubble radius, given a critical pressure condition in cavitation susceptibility meter experiments. The relationship between initial bubble diameter and critical pressure is described by an analytic solution that accounts for gas content. A model for the derivative of the cumulative nuclei histogram with respect to bubble diameter is proposed. An analytic expression is obtained that shows good agreement with decades worth of experimental data compiled by Khoo et al. (Exp. Fluids, vol. 61, issue 2, 2020, pp. 1–20) from ocean to water tunnels. The expression recovers the $-4$ power law that is observed experimentally.

In-flight electro-neutralisation electrospray for pulmonary drug delivery

Pulmonary drug delivery does not only provide non-invasive therapy for local lung diseases but also remarkably enhances systemic absorption of therapeutics owing to the tremendous surface area of the lung and fast transport of active molecules across the respiratory epithelia. In comparison to traditional delivery systems, electrohydrodynamic atomisation (EHDA) is superior in terms of size and production rate control but the high surface charges of resulting particles prohibit its use in drug delivery. To overcome this challenge, we developed an in-flight electro-neutralisation electrospray (IFENE) method which enables the generation of mists of particles in respirable size range with little to no charge. Our approach uses low-frequency alternating current (AC) to produce charge-neutralised sprays with initial velocity due to oppositely charged droplets combination. Experiments and simulations with pure liquid as the working solution were conducted to reveal the underlying mechanism. The applied frequency is found to be the main factor that influences spray stability and formation. Poly (vinylidene fluoride) (PVDF) and PVDF with curcumin solution were electrosprayed via IFENE, producing sprays of organic particles with controlled sizes and neutralised charges. The capability of coupling particle generation in the respirable size range (below 5 μm) and charge reduction (under 400 femtoamperes), along with its simple setup makes IFENE a promising platform technology in inhalation drug delivery.

Enhanced heat transfer and fluid motion in 3D nanofluid with anisotropic slip and magnetic field

Abstract A mathematical model is envisaged that discusses the motion of 3D nanofluids (NFs) with anisotropic slip influence magnetic field past a stretching sheet. The heat transportation phenomenon is analysed by melting effect, heat generation, and chemical reaction. The main motivation of this study is to analyse the behaviour of liquid motion and heat transfer (HT) of NFs because this study has huge applications in boiling, solar energy, and micropower generation, which are used in the engineering process. The physical governing partial differential equation is transformed into a coupled non-linear system of ordinary differential equations using suitable appropriate transformations. The translated equations are calculated using Runge–Kutta–Fehlberg method via shooting procedure. The physical characteristics of various parameters on velocities, concentration, and thermal fields are explored in detail. The HT is high in NFs when compared to pure or regular liquids for ascending values of heat source parameter and slip factor. Also, the skin friction coefficients via coordinate axes and rate of Nusselt number were analysed.

Metal- and binder-free dual-ion battery based on green synthetic nano-embroidered spherical organic anode and pure ionic liquid electrolyte

Dual-ion batteries (DIBs) have attracted extensive attention and investigations due to their inherent wide operating voltage and environmental friendliness. Nevertheless, the vast majority of DIBs employ metal-based anode active materials or electrolytes, which are relatively costly and unsustainable. Moreover, the utilization of binders and current collectors in the preparation of cathodes and anodes reduces the energy density to a certain extent, which weakens the advantages of DIBs. Here, we synthesized three types of binder-free nano-embroidered spherical polyimide anode materials composed entirely of renewable elements, paired with pure ionic liquid electrolyte without metal elements and flexible self-supporting independent graphite paper cathode without current collector, to construct a class of totally metal and binder-free DIBs. It significantly improves specific discharge capacity, energy density, cyclic stability, and fast charging performance while remarkably reducing costs and self-discharge rate. Additionally, we overcame the drawbacks of conventional synthesis methods and innovatively prepared nanoscale polyimide materials by a green and facile hydrothermal method, which effectively minimizes synthesis costs and avoids risks. This novel battery system design strategy will promote the advancement of low-cost, high-performance DIBs and could be a promising candidate for large-scale energy storage applications.

A Eulerian Numerical Model to Predict the Enhancement Effect of the Gravity-Driven Motion Melting Process for Latent Thermal Energy Storage.

Latent thermal energy storage (LTES) devices can efficiently store renewable energy in thermal form and guarantee a stable-temperature thermal energy supply. The gravity-driven motion melting (GDMM) process improves the overall melting rate for packaged phase-change material (PCM) by constructing an enhanced flow field in the liquid phase. However, due to the complex mechanisms involved in fluid-solid coupling and liquid-solid phase transition, numerical simulation studies that demonstrate physical details are necessary. In this study, a simplified numerical model based on the Eulerian method is proposed. We aimed to introduce a fluid deformation yield stress equation to the "solid phase" based on the Bingham fluid assumption. As a result, fluid-solid coupling and liquid-solid phase transition processes become continuously solvable. The proposed model is validated by the referenced experimental measurements. The enhanced performance of liquid-phase convection and the macroscopic settling of the "solid phase" are numerically analyzed. The results indicate that the enhanced liquid-phase fluidity allows for a stronger heat transfer process than natural convection for the pure liquid phase. The gravity-driven pressure difference is directly proportional to the vertical melting rate, which indicates the feasibility of controlling the pressure difference to improve the melting rate.

Optimization and degradation studies of cellulose transesterification to palmitate esters in superbase ionic liquid

Cellulose palmitates (CPs) were synthesized with varying degrees of substitution (DS) via a catalyst-free, homogeneous transesterification of cellulose in a novel superbase ionic liquid (SB-IL) system, specifically 5-methyl-1,5,7-triaza-bicyclo[4.3.0]non-6-enium acetate [mTBNH][OAc], combined with dimethyl sulfoxide (DMSO) as a co-solvent, using vinyl palmitate as the acylating agent. We examined the influence of reaction temperature, reaction time, and the molar ratio of vinyl palmitate to anhydroglucose unit (AGU) on the DS, which ranged from 0.5 to 2.3 under the given conditions. Notably, the reaction order of the three hydroxy groups was C6–OH > C2–OH > C3–OH. To elucidate the chemical structure of CPs and confirm the transesterification process, various spectroscopic techniques including 1H nuclear magnetic resonance (NMR), 13C NMR, heteronuclear single quantum correlation (HSQC), and solid-state NMR were employed. Higher reaction temperatures and extended reaction times led to a decrease in the DS of CPs, potentially due to the degradation of some of the involved chemicals during the transesterification process. We also investigated the stability of the pure ionic liquid (IL) and the IL + DMSO solvent system at elevated temperatures by heating them at 100 °C for 5 h, confirming their chemical integrity through 1H NMR analysis. Additionally, we assessed the compatibility between the solvent system and cellulose by subjecting a mixture of cellulose and the solvent system to 100 °C for 5 h. To compare the structures of untreated cellulose and regenerated cellulose, Fourier transform infrared (FT-IR) spectroscopy was employed. Furthermore, we determined the molar mass of both untreated cellulose and regenerated cellulose, as well as CPs synthesized at higher reaction temperatures and longer durations, using intrinsic viscosity measurements. Lastly, we examined the solubility properties of CPs.

Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer

The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.