Water Volume Concentration Research Articles

Stability Analysis of Pure Oil-Water Emulsion in Gravity-Based Separators

Abstract The purpose of this work is to investigate the stability of pure (emulsifier-free) oil-water emulsion in a gravity-based separator as a function of various parameters such as mixing speed, water volume concentration, temperature, and appearance. Only simple fluids (ExxsolTMD110 and distilled water) were used to form the dispersion in a separator of operational volume 200 ml and internal diameter of 60 mm. Data were gathered from a portable dispersion characterization rig where videos of liquid phase separation can be saved and scanned. The study considered a wide range of mixing speeds between 600 rpm and 2500 rpm, with elevated temperatures of 60 °C and 80 °C. Both types (oil-in-water (O/W) and water-in-oil (W/O)) of pure emulsion were studied. In addition, two volumetric water concentrations (WCs) were considered for each type to investigate its stability under the parameters tested (i.e., 25% and 50% WC for W/O emulsion and 75% and 90% WC for O/W emulsion). The stability of the emulsion was examined in terms of the separation profiles of the water and oil phase, oil/water mixture volume, initiation time of free phase separation and/or the final time of separation. Mixing speed was shown to drastically impact the stability of O/W emulsion, from a few minutes to over 4 h. Conversely, insignificant effects of mixing speed were seen for W/O emulsion as the emulsions overall separated in a few seconds. Although temperature accelerated the oil separation rates of 75% WC emulsions, it delayed the initiation time of water separation.

Water content monitoring in water-in-oil emulsions using a delay line cell

The extraction process of crude oil requires addition of water, resulting in complex emulsions, in which the phases must be separated before the petrochemical processing starts. An ultrasonic cell may be used to determine in real time the water content in water-in-crude oil emulsions. The water content of emulsions can be related to parameters, such as propagation velocity, density and relative attenuation. The ultrasonic measurement cell developed here is composed of two piezoelectric transducers, two rexolite buffer rods, and a sample chamber. It is an inexpensive and robust system. The cell measures the parameters at different temperatures and flow conditions. The tests were performed using emulsions with water volume concentrations from 0% to 40%. The experimental results show that this cell is able to obtain more precise parameters, when compared to similar ultrasonic techniques. The data acquired in real time may be used to improve the emulsion separation, decreasing greenhouse gases and energy requirements.

Water Content Monitoring in Water-in-Oil Emulsions Using a Piezoceramic Sensor

This work deals with a transmission-reception ultrasonic technique for the real-time estimation of the water content in water-in-crude oil emulsions. The working principle is the measurement of the propagation velocity, using two in-house manufactured transducers designed for water coupling, with a central frequency of about 3 MHz. Water-in-crude oil emulsions with a water volume concentration from 0% to 40% were generated by mechanical emulsification. Tests were carried out at three temperatures. The results showed that the propagation velocity is a sensitive parameter that is able to determine the water content, allowing for differentiating the concentrations of up to 40% of water. The main motivation is the development of techniques for non-invasive and real-time monitoring of the water content of emulsions in petrochemical processes.

Water Content Monitoring in Water-in-Crude-Oil Emulsions Using an Ultrasonic Multiple-Backscattering Sensor.

This work shows the application of an ultrasonic multiple-scattering sensor for monitoring water-in-petroleum emulsions. The sensor consists of a commercial ultrasonic transducer with an array of cylindrical scatterers placed in the near field. The scatterers are thin metal bars arranged in rows in front of the transducer. The backscattering signals were analyzed by calculating the wave energy and by a cross-correlation between signal segments; they were also used to determine the propagation velocity in the emulsions. The tests performed used emulsions with water volume concentrations from 0% to 50%. The results showed that both the signal energy and propagation velocity strongly depended on the concentration of water in the emulsion. Therefore, the ultrasonic multiple-scattering sensor can be used for on-line and real-time monitoring of the water content in water-in-crude-oil emulsions.

Explosive morning growth phenomena of NH3 on the North China Plain: Causes and potential impacts on aerosol formation

Atmospheric ammonia (NH3) as the most important alkaline gas in the atmosphere has attracted much attention in recent years due to its critical role in haze formation, especially on the North China Plain (NCP). Comprehensive studies are needed for investigating diurnal variations of NH3 and underlying mechanisms in different seasons and their potential impacts on atmospheric chemistry. In this study, continuous long-term observation (Mar. 2016 to May 2017) of NH3 at a rural site in the NCP was used to characterize the diurnal variation of NH3 in different seasons and to unveil its causes and potential impacts on atmospheric chemistry. NH3 concentrations displayed rapid increases during the morning, reaching very prominent peaks mostly between 8:00 to 11:00 LT. Such frequent (55%) morning peaks were mainly caused by the evaporation of dew and guttation water droplets. Average dew and guttation water volume concentrations of 750 mL m−2 was estimated for spring, which resulted in approximate NH3 emissions of 800 ng m−2 s− 1. Such high emission fluxes from dew and guttation water evaporation have never been reported before, suggesting dew and guttation droplets to be significant night-time reservoirs and strong morning sources for NH3. In light of recent studies putting forward that NH3 can promote the heterogeneous formation of HONO and nitrate under high humidity conditions, we investigated the differences in HONO and aerosol chemical composition diurnal variations between days with and without NH3 morning spikes during November. HONO, nitrate and sulfate concentrations were significantly higher for days with NH3 morning spikes, with HONO displaying a morning peak near that of NH3. These results demonstrate that the prevailing NH3 morning spikes on the NCP have significant influences on aerosol formation and atmospheric chemistry. NH3 emission mitigation strategies and regulations are urgently needed.

MODELLING WATER EXCHANGE BETWEEN COASTAL ELONGATED LAGOON AND SEA: INFLUENCE OF THE MORPHOMETRIC CHARACTERISTICS OF CONNECTING CHANNEL ON WATER RENEWAL IN LAGOON

The north-western part of the Black Sea Ukrainian coast is characterized by the presence of 12 marine lagoons which do not presently have permanent natural connections with the sea. Because of regional climate change, these lagoons have experienced a significant deficit of annual freshwater balance during the last decades and, consequently, an increase in salinity and eutrophication of their waters. One way to stabilize the hydroecological regime of lagoons is to maintain their regular connection with the sea via artificial connecting channels. The deepest and most prolonged Tyligulskyi Liman lagoon is used as an example to determine the morphometric characteristics (width, depth) of the artificial connecting channel which ensures bidirectional water exchange of the lagoon with the sea, i. e. its partial flushing. A numerical hydrodynamic model is used to estimate how the morphometric characteristics of the connecting channel influence the intensity of water exchange between the lagoon and the sea and of water renewal by seawater for the various parts of the lagoon. The dynamics of sea water volume concentration in reference points in the lagoon is used as an indicator of seawater intrusion into the lagoon and their degree of water renewal in its various zones. The proposed methodology could be used for other lagoons of the same type in the north-western part of the Black Sea.

Effect of solvent for tailoring the nanomorphology of multinary CuCo2S4 for overall water splitting and energy storage

Tailoring the nanomorphology of electrochemically active materials could significantly affect their resultant catalytic and charge storage performance. In this study, the nanostructured morphology of multinary CuCo2O4 and CuCo2S4 was tuned using a different volume concentration of water and ethanol resulting in different nano-shapes maintaining similar crystal structure. The electrocatalytic performance was analyzed for all the synthesized samples as the hydrogen (HER) and oxygen evolution catalyst (OER). The HER and OER study for CuCo2S4 sample synthesized using ethanol required a low overpotential of 158 mV to reach 10 mA/cm2 and 290 mV to achieve 20 mA/cm2, respectively. Furthermore, the electrolyzer cell using symmetrical electrodes required a low overall cell potential of 1.66 V to achieve a current density of 10 mA/cm2 and maintained stable performance for over 24 h, suggesting a promising bifunctional catalytic behavior. Furthermore, the synthesized samples were studied as electrodes for high-performance energy storage systems. The CuCo2S4 electrode showed an areal capacitance of 6.3 F/cm2 (3190.8 F/g) at a current density of 2 mA/cm2. The Ragone plot for the areal energy versus power density resulted to be 265 mWh/cm2 (132 Wh/kg) and 11.9 W/cm2 (5973 W/kg), respectively. Thus, from the overall study, it can be confirmed that tailoring morphology of nanostructured material such as CuCo2S4 could be a promising way for the advancement of energy generation and storage devices.

An investigation into the application of Al<SUB align="right">2O<SUB align="right">3nanofluid-based minimum quantity lubrication technique for grinding of Ti-6Al-4V

Nanofluids, suspensions of nanoparticles in base fluid, has shown attractive cooling and lubricating properties. The nano–coolants and nano–lubricants find applications in a wide variety of materials processing technologies. It is anticipated that, if properly employed, nanofluids usage could surpass the conventional cutting fluids in the future. Minimum quantity lubrication (MQL) technique also, has achieved a significant consideration in manufacturing processes to minimise the environmental loads caused by the usage of traditional cutting fluids. The aim of this work is to examine the potential of Al2O3 nanofluid under MQL mode to improve the grinding characteristics of Ti–6Al–4V alloy. 1% Volume concentration of water–based Al2O3 nanofluid was applied during the surface grinding operation using an indigenously developed MQL setup and the results have been compared with those of conventional coolant under both flood cooling and MQL mode.

Terahertz-wave water concentration and distribution measurement in thin biotissue based on a novel sample preparation

The measurement of water concentration and distribution in thin biotissues with terahertz (THz)-wave has been proposed. In this paper, a novel sample preparation approach was introduced to effectively preserve tissue freshness at room temperature. Excellent stability of this method was demonstrated by measuring the transmittance spectroscopy and imaging many times within a certain time. Moreover, the reliability of water volume concentration measurement with THz-wave was evaluated. Measurement results using THz-wave were in good agreement with volume concentration measurement results based on other quantitative methods. The results suggest that water concentration and distribution measurement in thin biotissues using THz-wave will be a potential modality for medical and biological diagnosis.

An experimental study of the evaporation characteristics of emulsified liquid droplets

This paper presents the results of an experimental investigation, into the effect of water in diesel and kerosene emulsions, on the evaporation time of a single droplet, on hot surfaces (stainless-steel and aluminum). Experiments are performed at atmospheric pressure, and initial water volume concentrations of 10, 20, 30, and 40%. The wall temperatures ranging from 100–460 °C, to cover the entire spectrum of heat transfer characteristics from evaporation to film boiling. Results show that, qualitatively, the shapes of emulsion evaporation curves are very similar to that of pure liquids. Quantitavely, there are significant differences. The total evaporation time, for the emulsion droplets is lower than that for diesel and kerosene fuels, and decreased as water initial concentration increases, up to surface temperatures less than the critical temperature. The value of the critical surface temperature (maximum heat transfer rate), decreases as initial concentration of water increases. In the film-boiling region, the evaporation time for the emulsion droplets is higher than for diesel and kerosene droplets, at identical conditions.

An Apparatus for Studying Condensed Impurity Systems in Liquid Helium

The design of an apparatus that ensures the injection of gaseous 4He with water vapor impurities or vapors of other molecular liquids into the experimental cell, which is filled with superfluid He-II, is described. It is shown that, when a 4Не + Н2О gas mixture condenses, porous semitransparent samples (icebergs) with a characteristic size of ∼1 cm form under the surface of the superfluid. The volume concentration of water in the samples is ≲1020molecules/cm3. When heated above Tλ, icebergs in normal He-I may decompose into ice and 4He. The temperature Tdat which intense disintegration begins depends on the pressure of the vapor above the liquid: Td≈ 2.5 K at a pressure of 0.2 atm, and, at a pressure of 1 atm, Tdrises up to 4 K. In an atmosphere of gaseous 4He, icebergs begin disintegrating into parts under warming above 1.8 K. This indicates the discovery of a new highly porous form of ice in liquid helium—a water gel, the dispersed phase (solid frame) of which is formed by water clusters surrounded by a solidified helium layer; liquid helium serves as a dispersing medium.

Volume and surface area size distribution, water mass and model fitting of GCE/CASE/WATOX marine aerosols

As a part of the Global Change Expedition/Coordinated Air‐Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX), size distributions of marine aerosols were measured at two altitudes of about 2750 and 150 m above sea level (asl) over the size range 0.1 ∼ 32 μm. Lognormal fitting was applied to the corrected aerosol size spectra to determine the volume and surface area size distributions of the CASE‐WATOX marine aerosols. Each aerosol size distribution was fitted with three lognormal distributions representing fine‐, large‐, and giant‐particle modes. Water volume fraction and dry particle size of each aerosol size distribution were also calculated using empirical formulas for particle size as a function of relative humidity and particle type. Because of the increased influence from anthropogenic sources in the continental United States, higher aerosol volume concentrations were observed in the fine‐particle mode near‐shore off the east coast; 2.11 and 3.63 μm3 cm−3 for free troposphere (FT) and marine boundary layer (MBL), compared with the open‐sea Bermuda area values; 0.13 and 0.74 μm3 cm−3 for FT and MBL. The large‐particle mode exhibits the least variations in volume distributions between the east coast and open‐sea Bermuda area, having a volume geometric median diameter (VGMD) between 1.4 and 1.6 μm and a geometric standard deviation between 1.57 and 1.68. For the giant‐particle mode, larger VGMD and volume concentrations were observed for marine aerosols nearshore off the east coast than in the open‐sea Bermuda area because of higher relative humidity and higher surface wind speed conditions. Wet VGMD and aerosol water volume concentrations at 15 m asl ship level were determined by extrapolating from those obtained by analysis of the CASE‐WATOX aircraft aerosol data. Abundance of aerosol water in the MBL serves as an important pathway for heterogeneous conversion of SO2 in sea salt aerosol particles.

An experimental study of the Leidenfrost evaporation characteristics of emulsified liquid droplets

Experimental observations of the evaporation characteristics of water-in-fuel emulsion droplets in film boiling on a hot horizontal surface are reported. Detailed measurements of the temporal variation of equivalent droplet diameter for water-in-heptane and water-in-decane emulsions are made at surface temperatures of 565, 620 and 680 K. Experiments are performed at atmospheric pressure and initial water volume concentrations of 10, 20, 35 and 50%. More qualitative characteristics are observed for emulsions of water in octane, nonane and dodecane. It is found that water/heptane and water/decane emulsions exhibit preferential vaporization such that either the water or hydrocarbon evaporate first (for decane or heptane emulsions, respectively). This result is revealed by an apparent discontinuity in the evolution of equivalent droplet diameter and is explained on the basis of a simple distillation limit model for evaporation. Results also show that the droplet evaporation rate decreases, and the total droplet evaporation time increases, with increasing water content. The initially opaque colored droplets appear to clear up during vaporization for several of the emulsions tested. Coalescence of the internal phase for water/octane and water/dodecane emulsions is also observed. Of the emulsions tested, only the water/heptane emulsions exhibit a disruptive characteristic at the end of the evaporation process.

Some features of a microexplosion of a drop of water-fuel emulsion

This paper presents a model of the microexplosion of drops of a waterfuel emulsion, based on the heterogeneous scheme for the formation of inclusions of a specific phase in superheated water. A drop of emulsion with radius R /SUB d/ , which includes a spherical volume of water is examined. It is shown that for a fixed volume concentration of water in the fuel, from the viewpoint of a microexplosion the case when one large particle of water rather than many small particles of water is present in the fuel drop is preferable.

Calculation of the density of aqueous solutions of strong electrolytes from individual ionic parameters

Based on a hypothesis verified earlier, according to which the concentration dependence of apparent molar volumes of ions in aqueous solutions is caused by their dehydration due to the decrease of the volume concentration of water, a method for the calculation of the density of concentrated aqueous electrolytes from individual ionic constants is proposed. The theory is verified by comparing with experimental data from the literature (420 solutions of 57 electrolytes).

Concentration dependence of correlation times from proton NMR relaxation in hydrous melts

Proton spin–lattice relaxation times (T1) for hydrous melts of Ca(NO3)2 containing 2.8, 4.0, 8.0, and 16.O moles H2O/mole salt (55.5 to 2.32 moles H2O/l) at temperatures between 290 and 390 K are analyzed in terms of intramolecular and intermolecular contributions. Rotational correlation times for water (τrot) are estimated from the relaxation rates in the high temperature (narrow line) region using intermolecular correlation times (τinter) estimated from melt viscosities or from diffusivities of protons or of dilute solute ions (Cd2+). The ratio τinter/τrot increases from about 2.5 in pure water to about 17 in the viscous melt Ca(NO3)2-2.8 H2O, suggesting a much greater medium effect on translational than on rotational motion. An empirical relation was found that quantitatively correlates the dependence of the relaxation rate, varying over three orders of magnitude, with viscosity (or water diffusivity) and the volume concentration of water at all of the compositions and temperatures investigated.

Rheological changes in emulsions on aging: III. At very low rates of shear

Creep compliance-time studies on water-in-Nujol emulsions (30%, 50%, 65% wt/wt disperse phase) stabilized by 1.5% (wt/wt) sorbitan monooleate at a shear stress of 4.9 dynes/cm. 2 indicate that their rheological parameters change drastically during the first hours of aging. The experimental data suggest that the elastic moduli almost disappear, and that the viscosity moduli decrease by as much as one order of magnitude or more. These changes are believed to be associated primarily with the rapid coagulation of globules with diameters not exceeding 0.5 μ. Following rapid flocculation globules associate as dense cores which are linked together by projection of less densely packed globules. With increasing volume concentration of water the cores become larger and the projections shorter. Coalescence of globules during aging produces a more open flocculate structure. The attraction forces between globules in close contact are modified substantially by the adsorbed layers of emulsifying agent so that the attraction potential changes slowly with decreasing distance of globular separation. Nevertheless, flocculated globules are bound together by significant attraction forces, so it is concluded that either the repulsion potential in W/O emulsions is smaller than previously thought, or the adsorbed layer of emulsifying agent reduces the attraction potential by less than calculation suggests.

Solubility of salts in aqueous solutions of electrolytes

1. A method is proposed for determing solubility, in which the latter is considered as the product of the solubility coefficient and the activity. 2. According to the equation deduced, the solubility coefficient depends on the electrostatic interaction of the ions and the volume concentration of water. 3. Calculated data were confirmed by experimental solubility isotherms of salts in aqueous solutions of electrolytes.