Concentration In Liquid Phase Research Articles

Experimental Study on the Impact of Sorption-Desorption on Nitrate Isotopes

Nitrate pollution is a global environmental problem, and mean nitrate levels have risen by an estimated 36% in global waterways since 1990. Tracing nitrate sources is important for water quality management, and nitrate isotopes (δ15N-NO3− and δ18O-NO3−) are commonly used for this purpose because of the different isotopic compositions of different sources. However, the impact of nitrate sorption on matrix and desorption from matrix on N and O isotopic composition of nitrate in liquid phase has not been well clarified. To explore the mechanism for the changes in nitrate concentration and isotopes in liquid phase during sorption and desorption, this study took a shale sample (enriched in clay minerals and commonly exposed in the Earth), conducted a series of laboratory experiments for nitrate sorption and desorption, and studied the impact of sorption and desorption on nitrate N and O isotopic composition in liquid phase. The results showed that the shale sample exhibited a rapid sorption and desorption rate for nitrate in the surface water samples, with the nitrate concentration in the solution decreasing from 14.3 mg/L to 4.1 mg/L within 5 min. The sorption data fit the Langmuir model better than that of the Freundlich model. The maximum possible sorption (Qmax) for the shale sample was estimated to be 46 μg/g. Preliminary laboratory experiments showed that changes in δ15N-NO3− values were not obvious, and changes in δ18O-NO3− values in liquid phase were minor during sorption and desorption of the shale sample, suggesting that nitrogen isotopic fractionation can be neglected, and the sorption of nitrate by the shale sample has a very limited impact on the distribution of nitrate isotopes in liquid phase. However, the impact of nitrate desorption on the nitrate isotopes in liquid phase depends on the isotopic composition of exchangeable nitrate in the solid phase, which may be related to antecedent water–rock interactions. This study provides important information for elucidating the evolution mechanism of nitrate and its isotopic compositions following sorption-desorption, and is conducive to revealing the nitrogen cycle law in the environment.

Correlation between preparation techniques and frictional properties of cellulose nanocrystals as additives in water-based lubricants

To explore the tribological characteristics of cellulose nanocrystals derived through various preparation techniques when utilized as additives in water-based lubricants, two types of cellulose nanocrystals (S-CNC and C-CNC) were chosen. These were produced via sulfuric acid hydrolysis and oxidation methods. The morphology and structural features were assessed through techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), laser confocal Raman spectroscopy, elemental analysis, scanning electron microscopy (SEM), and laser particle size analysis. According to thermogravimetric analysis (TGA), the thermal stability of S-CNC is slightly superior to that of C-CNC. S-CNC exhibits liquid crystallinity when the concentration exceeds 0.5 %, whereas C-CNC does not display liquid crystallinity at any concentration tested. Further investigation was conducted on the frictional properties of the two types of CNCs using a UMT reciprocating friction tester. The results indicate that both types of CNC exhibit significant friction reduction properties at various additive concentrations, provided the addition does not exceed w=1 %. When below their respective liquid crystalline phase concentrations, the friction reduction performance of S-CNC is slightly inferior to that of C-CNC; however, when above the liquid crystalline phase concentration, the friction reduction performance of S-CNC surpasses that of C-CNC. The addition of w=0.5 % S-CNC leads to a relative reduction of 63.4 % in the friction coefficient compared to the base system. Analysis of the steel plate surface contact angle and post-wear surface suggests that the lubrication mechanism of CNC involves the adsorption of polar functional groups such as hydroxyl or carboxyl groups from the CNC structure onto the friction pair surface, forming a lubricating protective film to varying degrees. Additionally, the liquid crystalline structure of S-CNC facilitates the formation of an ordered lubricating film, further enhancing the frictional properties. These findings provide valuable insights into the application of nanocellulose crystals as lubricant additives.

Simulation of anaerobic biodegradation process in a tubular bioreactor with a biofilm layer: Steady-state and unsteady-state conditions

In this paper, anaerobic biodegradation process in a tubular bioreactor with an inner biofilm layer for steady-state and unsteady-state conditions are simulated. The effects of various parameters including bioreactor diameter, fraction of active biomass transferred to liquid phase, and residence time of the liquid on bioreactor performance are examined. Simulations indicate that decreasing diameter of bioreactor leads to increasing degree of conversion of the substrate in liquid phase and decreasing dimensionless concentration of the substrate in biofilm. With an increase in the fraction of active biomass transferred to liquid, substrate concentrations in liquid and biofilm slightly vary. Increased residence time of the liquid phase results in the degree of conversion of substrate goes up, but substrate concentration in biofilm lowers a little. In addition, it is found that biomass concentration of liquid phase is boosted with decreased bioreactor diameter and increased residence time of liquid. A proportional-integral controller is designed and the tuned parameters of KP=−0.131 and KI=0.02 are obtained using genetic algorithm. It is observed that controller regulate well the degree of conversion of the substrate within 120 s for both servo and regulatory modes.

Decomposition of Sulfide Phases and Subsequent Matte Collection in the Black Top of a Platinum Group Metal Smelter

ABSTRACT This study explored, on a laboratory scale, how matte separates from the gangue in the black top of a PGM smelter. Two PGM concentrates, one with high sulfide content (17.3 mass%, Platreef concentrate) and the other with low sulfide content (1.3 mass%, UG-2 concentrate), were studied in the temperature range of 800°C to 1480°C, which is the temperature gradient across the black top. The results showed that effective matte separation occurs at temperatures when the matte is completely molten, and a substantial amount of liquid silicate phase has formed. The main matte separation mechanism is the coalescence of sulfide prills and their gravitational settling through the continuous path created by the liquid silicate phase. Complete matte separation occurs at lower temperatures in Platreef concentrate (1400°C in Platreef concentrate vs. 1480°C in UG-2 concentrate), due to the higher concentration of liquid silicate phase of lower viscosity, as well as the higher amount of sulfide minerals in this concentrate. PGMs already dissolve and collect in a nickel-iron-based alloy associated with the matte at temperatures as low as 900°C.

Phase-field simulation study on dendritic growth behavior during bilateral directional solidification

The directional solidification technique can uniform the crystal growth direction within the material, but does not remove the lateral side branches of the axial main arm during the growth process. The influence of such lateral side branches existing in the directionally solidified dendritic organisation on the mechanical properties of the material cannot be neglected. In this paper, based on the Kim-Kim-Suzuki (KKS) phase-field model, the competitive behaviour of lateral secondary dendrites between the two main arms under different boundary conditions and non-synchronous growth conditions is investigated for Fe-0.5 %C alloys. In addition, the diffusion and enrichment rules of solutes are analysed by the distribution of solutes. The results show that the molten pool is spherical without external force, and the size distribution of the molten pool is as follows: dendrite tip collision zone > dendrite root > dendrite wall, and the solute segregation rule is the same; The spacing of the main arms has little effect on the concentration values between the dendrites, and the solutes are very symmetrically over the entire computational region; The dendrite tip interface concentration during the stable phase of dendrite growth is 0.89 %. Without considering the initial liquid-phase concentration, the concentration in the collision zone at the dendrite tip is approximately twice the concentration at the tip of the dendrite in the stable period, which is 1.28 %, when the bilateral dendrites are encountered. Dendrites always collide preferentially on the centreline of the included angle under non-parallel conditions, and solute-enriched zones also occur on the centreline of the included angle; During the curved surface bilaterally directional solidification process, when the left and right sides have the same shape of surfaces, the solute enrichment at the end of solidification is on the centreline. For the case of a single planar boundary, the solute-enriched region is influenced by the curved surface and is similar to the initial curved surface profile.

A computational study of solidification kinetics in multicomponent alloys

Recent advances in materials processing technologies highlight the need to understand solidification kinetics in multicomponent alloys. Using a finite interface dissipation phase field model, we investigate planar front solidification rates in ternary alloys, used as a model system, as a function of various mass transport processes and nonequilibrium conditions. Simulation results reveal that the off-diagonal diffusion coefficients play an important role in controlling the solid–liquid (S–L) interface velocity and solute partition coefficients. Specifically, under various rapid solidification conditions negative values for the off-diagonal diffusion coefficients increase the solute partition coefficients due to the depletion of liquid phase concentrations ahead of the S–L interface. Given an undercooling, the S–L interface velocity increases with decreasing the off-diagonal diffusion coefficients. In broad terms, our work quantifies the role of coupled mass transport processes and nonequilibrium effects in solidification rates of multicomponent alloys.

In Situ Formed Organic Ion-Associate Liquid-Phase Microextraction without Centrifugation from Aqueous Solutions Using Thymol Blue and Estrogens

In this study, we present a method for ion-associated liquid phase (IALP) separation and concentration of analytes from an aqueous matrix into an IALP formed in situ by the charge neutralization reaction of organic cations and anions, without centrifugation. The effects of various factors on the extraction efficiency and other parameters are investigated, whereas no instrumental stirring, such as vortexing or ultrasonics, is required because the solvent (IALP) is formed in situ. The organic cation and anion used are ethylhexyloxypropylammonium and dodecyl sulfate, respectively. The developed in situ IALP microextraction method for phase separation without centrifugation is tested using the thymol blue dye and several endocrine disruptors. The tested endocrine disruptors (bisphenol A, 17β-estradiol, 17α-ethinylestradiol, and estrone) are analyzed via high-performance liquid chromatography/fluorescence detection, with respective detection limits of 0.02, 0.02, 0.02, and 0.4 μg L−1, and the corresponding enrichment factor ranging from 47 to 71. This IALP microextraction method can be used to separate and concentrate environmental water samples of different matrices. The employed IALP is fast and easy to use, enables an approximately 100-fold analyte concentration, and has a high affinity for estrogens, thus holding promise for the separation, concentration, and quantitation of diverse trace analytes.

CO 2 Capture in Liquid Phase and Room-Temperature Release and Concentration Using Mechanical Power

CO ₂ Capture in Liquid Phase and Room-Temperature Release and Concentration Using Mechanical Power

Predicting asphaltene precipitation in CO2 flooding processes using artificial intelligence techniques

The removal of asphaltene depositions from crude oil wellbores and tubing is a very difficult and expensive process. Therefore, a very accurate predictor for the Asphaltene Precipitation (AP) is a very important tool for decision making. In this paper, the AP during the injection of carbon dioxide into crude oil reservoirs is forecasted using an artificial neural network (ANN). For this purpose, experimental data is collected from six different oil fields. 70% of the collected data is utilized for training and to develop the proposed ANN. Trainlm training algorithm was found to be the best ANN architecture for AP forecasting. In order to validate the capability of the designed ANN 30% of the unseen data is utilized for validation. The forecasting results show the Mean Square Error (MSE) of the forecasting is 0.0018 that confirms the high accuracy of the model. In order to evaluate the capability of the proposed methodology, the results of proposed ANN are compared with modified Hirschberg model. Comparison confirmed the proposed ANN has better capability and higher accuracy. In the final stage, the effects of various operating parameters on the AP during gas injection are examined. The results show that the most sensitive parameter is the reservoir temperature. In addition, there is a high correlation between an increase in the AP with an increase in carbon dioxide concentration in liquid phase.

Remediation of oil-drilling cuttings by ozonation in a bubble flow reactor

Oil-drilling cuttings (ODCs) are the major wastes generated during oil/gas exploration and extraction. In the present work, a new method based on ozonation is suggested for the remediation of ODCs at ambient conditions, without pre-drying. During the ozonation process, the pressure drop across the gas phase along with the pH, redox potential, and temperature of liquid phase are monitored with the aid of built-in sensors. Occasionally, solid and liquid samples are collected to measure the total organic carbon (TOC) of each phase as a function of time, while the concentration of the total petroleum hydrocarbons (TPH) is measured before and after the completion of treatment. The maximum TOC removal efficiency for the solid phase reached ∼60% and that of TPH ∼ 40% whereas the energy efficiency was ∼ 0.1 kWh/g-TOC. The main mechanisms of ODC remediation are the mass-transfer of organic species from the solid to aqueous phase, and the direct oxidation by dissolved ozone, whereas their synergistic action is reflected in fluctuations of TOC concentration in liquid phase. The TOC removal efficiency of the solid phase increases with the flow rate decreasing, the ozone concentration increasing, and the mass ratio of ODC to seawater (SW) increasing. Ozonation in the liquid phase after its separation from treated ODC proceeds very fast through the direct oxidation by ozone. The process energy efficiency is favoured for low ozone concentration, low gas flow rate, high ODC to SW mass ratio, oxygen as feed gas, and without the addition of sodium dodecyl sulphate (SDS) as surfactant.

System identification and state estimation of a reduced-order electrochemical model for lithium-ion batteries

Lithium-ion batteries commonly used in electric vehicles are an indispensable part of the development process of decarbonization, electrification, and intelligence in transportation. From intelligent designing, manufacturing to controlling, an intelligent battery management system plays a crucial role in the long life, high efficiency, and safe operation of lithium-ion batteries. As a first-principle model, the electrochemical parameters of the electrochemical model have physical meanings and reflect the internal state of the lithium-ion batteries. The application of electrochemical models in an advanced intelligent battery management system is a future trend that promises to mitigate battery life degradation and prevent safety incidents. The reduced-order electrochemical model is expected to alleviate the requirements of advanced battery management systems for high accuracy and fast computing of lithium-ion battery models. However, the existing model order reduction methods have the drawbacks of high computational complexity and small application scope, so that inconvenient to apply onboard. In order to solve the existing obstacles, this paper applies the pseudo-spectral method to solve the solid-phase diffusion equation, while the liquid-phase concentration equation is simplified by the Galerkin method. Subsequently, a particle swarm optimization algorithm is used to identify 11 parameters of the electrochemical model. To further improve the accuracy of the electrochemical model, the above system identification method is applied to segment identification, especially for high or low state-of-charge (SoC) conditions in this study. Finally, based upon the derived model, estimation of SoC is performed using a particle filter. The results show that the proposed reduced-order electrochemical model achieves a low Mean Absolute Error (MAE) of 8.4 mV and a MAE of 0.54 % on estimation of SoC based on the envisaged particle filter. This work is expected to provide the basis for the subsequent development of lithium-ion battery electrochemical models with smaller identification parameters and faster identification processes.

Modeling of a bubble column for CO2 removal by absorption with NaOH

CO2 capture experiments were carried out in a small-scale bubble column reactor using alkaline solutions of sodium hydroxide. The results of the experiments show that a higher NaOH content in the liquid phase and elevated CO2 concentrations in the gas mixture led to a higher CO2 removal efficiency. A mathematical model was developed to describe the CO2 absorption as a function of CO2 gas inlet and OH- concentrations at low CO2 and OH- concentrations. The CO2 uptake at high OH- concentrations (high pH) was accurately predicted by the model, whereas the CO2 uptake at lower OH- concentrations could not be predicted with the same accuracy.

Experimental monitoring of CO2 hydrate slurry crystallization by heat flux rate determination in a jacketed reactor

CO2 hydrate slurries are promising phase change materials for secondary refrigeration applications. However, the difficulty of experimentally evaluating the crystallization kinetic of slurries limits their industrial use. Hydrate crystallization kinetics monitoring performs traditionally by a reactor mass balance. However, this method requires assumptions on CO2 liquid phase concentration and the hydration number. This work outlines the development of a specific method to determine kinetics thanks to the direct measure of heat flow through the reactor jacket and its evaluation compared with the mass balance method. The results of each method are then obtained by testing the two kinetic parameters of stirring speed and propeller type. The final hydrate mass fractions obtained with both methods are in good agreement, but the kinetic obtained by the mass balance method is faster than by the heat balance method.

Numerical simulation of single bubble growth and heat transfer of R32+R1234yf binary mixtures during saturated pool boiling

As a promising alternative refrigerant for meeting carbon reduction targets, R32+R1234yf binary mixtures combine the thermal performance of R32 with the environmental performance of R1234yf. Since the degree of heat dissipation during the boiling process is closely related to bubble behavior, the bubble growth and heat transfer characteristics of R32+R1234yf mixtures must be understood in depth. Accordingly, this study proposed a numerical model for single bubble growth during nucleate pool boiling of mixtures. Numerical simulations of single bubble growth in R32, R1234yf, and four binary mixtures thereof were conducted. Owing to the preferential evaporation of the more volatile component, a low concentration region of R32 appeared in the liquid near the heating surface, while the concentration of R32 in the vapor was generally higher than that in the liquid. The evaporation heat flux at the bubble interface in the mixtures was significantly lower than in pure R32, indicating that the existence of mass transfer resistance considerably reduced the heat transfer capacity of mixtures. In contrast to a pure fluid, the microlayer evaporation in a mixture might terminate owing to an increase in the local bubble point temperature, and two modes of microlayer evaporation—called “bubble-point-controlled mode” and “thickness-controlled mode”—were identified accordingly. The total heat transferred during bubble growth first decreased and then increased with an increase in the bulk concentration of R32; a minimum value was observed at an R32 mol fraction of approximately 0.4. This result is consistent with the observed variation in the difference between the vapor and liquid phase concentrations. Overall, this study provides a detailed description of the mass and heat transfer characteristics during single bubble growth in binary mixtures, contributing to a deeper understanding of the associated boiling heat transfer mechanisms.

Ag-based π-complexation adsorbent for paraffin/olefin separation

ABSTRACT With the massive requisition of light olefins in dedicated areas of petrochemical industry, adsorption separation approaches are developed to meet the requirements. The literature studying long-chain olefins/alkanes is scarce, and the actual adsorption capacity of liquid-phase is rarely studied. In this paper, the adsorption process of Ag-10× zeolite for long-chain alkanes/olefins was systematically studied, the preparation conditions and operating conditions of the zeolite were investigated. The samples were characterized by XRD, BET and XPS. The results show that silver ions were uniformly dispersed on the surface of the zeolite. The actual adsorption capacity of the modified zeolite was determined in intermittent experiments by liquid phase concentration difference and pore volume correction. The experimental data were fitted and the results showed that the Langmuir isotherm equation was more appropriate for adsorption, indicating that the adsorbent surface was homogeneous. The quasi-secondary kinetic chemical equation was consistent with the adsorption of olefins by the modified 10× zeolite, indicating that the process was a chemisorption process. Experimental results shows that Ag-10× zeolite is an excellent adsorbent for separating long-chain olefins/alkanes mixed systems.

Thickness dependence of resistive switching characteristics of the sol–gel processed Y2O3 RRAM devices

In this study, yttrium oxide (Y2O3)-based resistive random-access memory (RRAM) devices were fabricated using the sol–gel method. The fabricated Y2O3 RRAM devices exhibited conventional bipolar RRAM device characteristics and did not require a forming process. The Y2O3 film thickness was controlled by varying the liquid-phase precursor concentration. As the concentration increased, thicker Y2O3 films were formed. In addition, the concentration of oxygen vacancies increased. The RRAM device properties were not observed for thin Y2O3 films, which had the lowest oxygen vacancy concentration. Moreover, RRAM devices, which consisted of the thickest Y2O3 films with the largest oxygen vacancy concentration, showed poor non-volatile properties. The optimized Y2O3-based RRAM devices with a thickness of 37 nm showed conventional bipolar RRAM device characteristics, which did not require an initial forming process. The fabricated RRAM devices showed a high resistance state to low resistance state ratio of over 104, less than +1.5 V of SET voltage, and −15.0 V of RESET voltage. The RRAM devices also showed promising non-volatile memory properties, without significant degradation after 103 s retention and 102 cycle endurance tests.

Evaluation of Vaporizing Diesel Spray with High-Speed Laser Absorption Scattering Technique for Measuring Vapor and Liquid Phase Concentration Distributions

The Conventional Laser Absorption Scattering (C-LAS) technique is used to measure the mixture concentration and visualize the vapor phase. The former is determined by the attenuation of visible and ultraviolet light whereas the latter is achieved via light absorption and scattering theory. The C-LAS uses the Nd: YAG pulsed laser and CCD cameras to provide one spray shot at a particular instance which requires time and effort. However, the temporal measurement of a single spray shot is not possible. To record the distribution of the whole vapor phase in an injection event and measure liquid and vapor concentrations inside the spray, a High-Speed Laser Absorption Scattering (HS-LAS) technique was developed. The HS-LAS consists of continuous diode light sources, high-speed video cameras, and an image intensifier for UV light, which can provide the temporal variation of a single-shot spray. In the experiment, a commercial seven-hole injector with a hole diameter of 0.123 mm allowing high injection pressure of up to 100 MPa was used to avoid the potential inconsistencies with a single-hole test injector. The diesel surrogate fuel which consists of 97.5% n-tridecane and 2.5% of volume-based 1-methylnaphthalene was used. The injection amount of 5.0 mg/hole was selected to investigate the structure and mixture formation process of the spray. The findings of the experiments show that this imaging approach is a promising diagnostic technique for concurrently obtaining quantitative information on the quantity of vapor and droplets in a fuel spray. Furthermore, the turbulent/vortex fluid dynamics’ temporal development/variation can be investigated.

The Flory–Huggins Isotherm and Water Contaminant Adsorption: Debunking Some Modeling Fallacies

The Flory–Huggins (FH) isotherm first appeared in the literature of water contaminant adsorption in the mid-2000s. It has come into the limelight and received considerable attention in recent years, in large part due to regular coverage in review articles. Here, we point out that a linear form of the FH isotherm is incompatible with the original nonlinear version. We show conclusively that the original FH isotherm was destroyed beyond recognition by the linearization method. As a result, the linearized FH isotherm suffers from the following serious defects: (1) Its parameter estimates are incorrect and nonsensical. (2) It is not possible to plot standard isotherm curves in the form of adsorbed phase concentration versus liquid phase concentration. These anomalies, or “red flags”, that arise in the use of the linearized FH isotherm in data correlation are reported for the first time. To avoid publishing meaningless research, it is advisable to use the original form of the FH isotherm in data fitting. To go beyond routine application (e.g., simple data correlation and thermodynamic calculation), this work describes a novel application that uses the FH isotherm to evaluate the energy distribution of heterogeneous adsorbents.

A 3D distributed circuit-electrochemical model for the inner inhomogeneity of lithium-ion battery

Performance degradation and operational safety are vital issues for lithium-ion batteries. After summarizing each battery failure accident, it is found that local defects caused by the inconsistency within the battery are one of the critical reasons for battery failure. To study the influence of the internal inconsistency of the battery on its safety performance, a 3D distributed circuit and electrochemical coupling model that can reflect the internal structure of the battery are established. Moreover, the model’s solid-phase potential and liquid-phase lithium ion concentration are corrected to improve the simulation accuracy. The RMSE of the model is less than 10 mV under 1.0 C constant current charging condition and dynamic discharge condition. Based on the proposed distributed model, this paper investigates the influence of the cell size, tab position, and other structural parameters on the internal inconsistency of the cell. And the phenomenon of “current reversal” and the possible local lithium deposition away from the tab position is discovered. The model’s correctness and efficacy in simulating internal inconsistencies are further illustrated by reproducing the local lithium deposition of a homemade LFP cell and a commercial NCM cell by controlling the charging current.

Visualization of concentration polarization in thick electrodes

The manufacturing of the thick electrodes is vital for lithium-ion batteries (LIBs) to be widely industrialized since it can effectively elevate the energy density of LIBs. However, there is a serious liquid-phase concentration polarization in thick electrodes under high current density, resulting in poor electrochemical reaction kinetics. More importantly, concentration polarization will lead to the gradient distribution of the chemical properties for active materials, which is difficult to characterize. Herein, to reveal the influence of concentration polarization the crystal structure difference of the active materials in thick electrodes during charge-discharge process is explored. Then, the concentration polarization is verified in the configuration of thin-electrode-stacking cells (S-cells) for the first time by determining the Li content of each thin electrode in S-cells. Furthermore, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is applied to visualize the gradient distribution of Li solid-phase content on the section of the thick electrodes under high rates. Additionally, to alleviate the concentration polarization, the holes array is constructed on thick electrodes to enhance rate capability, and the mechanism of that was clarified by electrochemical simulation. This work will provide promising methods for studying the concentration polarization of thick electrodes in the future.