Impurities In Liquids Research Articles

Investigation of the potential of application Frac-Pack technology as a solution to the problem of sand control and increasing the production of high-viscosity oils at M field

Background: In this paper, the potential of applying hydraulic fracturing with the installation of a gravel pack in the Cretaceous horizons of the M field is investigated. The relevance of the work is due to the fact that today the selection of optimal technologies to increase the rate of oil production from the Cretaceous deposits an open platform for proposals and discussions. The low oil recovery coefficient is due to the existing restrictions on the oil production process: high oil viscosity, the presence of gas and water-oil zones, abundant sand production in a poorly cemented reservoir.
 Aim: The purpose of the work is to study the potential application of Frac-Pack technology in the wells of the M field.
 Materials and methods: In order to assess the potential of using Frac-Pack in a special FracPro software, a model of geomechanical and filtration properties of the formation was developed and a simulation of the design with various injection parameters was performed. Based on the results of laboratory studies of the content of mechanical impurities in liquids sampled at the M field, the diameter of the proppant and the flow section of the filter were determined.
 Results: As a result of the study, hydraulic fracturing was simulated for a well from a sample of potential candidates, the oil flow rate was calculated after the application of the proposed technology, materials for the implementation of Frac-Pack technology were selected based on laboratory studies.
 Conclusion: The study showed that the proposed pre-development strategy is the most optimal for shallow wells of the M field, as it is aimed not only at solving the problem of combating the removal of mechanical impurities, but also increasing oil production.

Comparison of Perfluorocarbon Liquids Cytotoxicity Tests: Direct Contact Versus the Test on Liquid Extracts.

The purpose of this study is to compare the in vitro cytotoxicity tests according to the ISO 10993-5 (2009) standards using direct contact and the test on liquid extracts of compounds previously identified as possible toxic impurities in perfluorocarbon liquids (PFCLs) for use in vitreoretinal surgery. Compounds including perfluorooctanoic acid (PFOA), 1H-perfluorooctane (1H-PFO), 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane were analyzed by 19F NMR before and after extraction using an aqueous solution and tested by both the direct contact and liquid extract tests in L929, BALB 3T3, and ARPE-12 cells. The concentration that reduced in vitro cell viability by 30%, the cytotoxicity concentration threshold (CC30), was determined for each compound. 19F NMR spectroscopy confirmed the immiscibility of perfluoro-n-octane (PFO) and 1H-PFO and the solubility of PFOA with the extraction vehicle. The other samples reacted with the extraction vehicle, releasing fluoride ions. Using the direct contact test, the CC30 of PFOA, 1H-PFO, 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane corresponded to 48 124, 50, 14, 8035, and 46 ppm, respectively. The method on liquid extracts did not detect cytotoxicity in three out of five tested compounds, and CC30 could not be determined. In conclusion, the in vitro cytotoxicity test by direct contact revealed a positive correlation between cell toxicity and the concentration of the tested substance. Conversely, the test on liquid extracts hardly detected the cytotoxicity of toxic impurities in PFCLs. Thus, only the cytotoxicity test by direct contact, according to ISO 10993-5 (2009), is a sensible and reliable method to detect possible cytotoxic impurities in PFCLs to guarantee patient safety.

Fractional Angular Momentum and Anyon Statistics of Impurities in Laughlin Liquids.

The elementary excitations of a fractional quantum Hall liquid are quasiparticles or quasiholes that are neither bosons nor fermions, but are so-called anyons. Here we study impurity particles immersed in a quantum Hall liquid that bind to the quasiholes via repulsive interactions with the liquid. We show that the angular momentum of an impurity is given by the multiple of a fractional "quantum" of angular momentum, and can directly be observed from the impurity density. In a system with several impurities bound to quasiholes, their total angular momentum interpolates between the values for free fermions and for free bosons. This interpolation is characterized by the fractional statistical parameter of the anyons, which is typically defined via their braiding behavior.

A comparison study on the properties of 1,3-dialkylimidazolium tetrafluoroborate salts prepared by halogen-free and traditional method

A series of 1,3-dialkylimidazolium tetrafluoroborate salts had been prepared via one-step alkylation of N-alkylimidazole with trialkyloxonium salts and traditional two-step method, respectively. The possible impurities in these ionic liquids (ILs) such as Cl−, Br−, Na+ and alkyl imidazoles were measured. Detailed characterizations of two approaches in the ILs properties and performances such as spectroscopic properties, phase behavior, viscosity, refractive index, and electrochemical properties were systemically conducted. The obtained results showed that the variety of synthesized methods resulted in the distinct changes in physicochemical properties for the same IL. Therein, the comparison of spectroscopic properties and phase behaviors for the employed ILs were emphasized. Furthermore, in most cases, the ILs prepared by traditional two-step possessed the higher viscosity, lower refractive index as well as lower ionic conductivity than that of ILs prepared by one-step. It was worth noting that the 1-decyl-3-ethylimidazolium tetrafluoroborate ([DEIm]BF4) prepared with the traditional and trialkyloxonium methods respectively exhibited distinctly different phase and fluorescence behaviors. The reason might be attributed to the significant improvement on the purities of ILs by the one-step strategy.

Designing Square Two-Dimensional Gold and Platinum

Square atomic configurations of two-dimensional gold and platinum are designed on the basis of density functional theory calculations. Calculations reveal that Au9 and Pt9 clusters form energetically stable perfect square structures. Combining and alternating two Au9 and two Pt9 allows for the formation of infinite square two-dimensional sheets of Au9, Pt9, and Au18Pt18. The electronic density of state reveals that two-dimensional Au9, Pt9, and Au18Pt18 retain metallic characteristics whereas two-dimensional Pt9 and Au18Pt18 also possess magnetic properties. In addition, the multilayered two-dimensional Au9 and Au18Pt18 of up to five layers and four layers, respectively, are designed. Two dimensional Au9, Pt9, and Au18Pt18 could have potential applications toward filtering gases or impurities in liquids as well as electronics.

Electrochemistry of Iodide, Iodine, and Iodine Monochloride in Chloride Containing Nonhaloaluminate Ionic Liquids.

The electrochemical behavior of iodine remains a contemporary research interest due to the integral role of the I(-)/I3(-) couple in dye-sensitized solar cell technology. The neutral (I2) and positive (I(+)) oxidation states of iodine are known to be strongly electrophilic, and thus the I(-)/I2/I(+) redox processes are sensitive to the presence of nucleophilic chloride or bromide, which are both commonly present as impurities in nonhaloaluminate room temperature ionic liquids (ILs). In this study, the electrochemistry of I(-), I2, and ICl has been investigated by cyclic voltammetry at a platinum macrodisk electrode in a binary IL mixture composed of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2mim][NTf2]). In the absence of chloride (e.g., in neat [C2mim][NTf2]), I(-) is oxidized in an overall one electron per iodide ion process to I2 via an I3(-) intermediate, giving rise to two resolved I(-)/I3(-) and I3(-)/I2 processes, as per previous reports. In the presence of low concentrations of chloride ([Cl(-)] and [I(-)] are both <30 mM), an additional oxidation process appears at potentials less positive than the I3(-)/I2 process, which corresponds to the oxidation of I3(-) to the interhalide complex anion [ICl2](-), in an overall two electron per iodide ion process. In the presence of a large excess of Cl(-) ([I(-)] ≈ 10 mM and [Cl(-)] ≈ 3.7 M), I(-) is oxidized in an overall two electron per iodide ion process to [ICl2](-) via an [I2Cl](-) intermediate (confirmed by investigating the voltammetric response of ICl and I2 under these conditions). In summary, the I(-)/I2/I(+) processes in nonhaloaluminate ILs involve a complicated interplay between multiple electron transfer pathways and homogeneous chemical reactions which may not be at equilibrium on the voltammetric time scale.

On the mechanism of the unwanted acetylation of polysaccharides by 1,3-dialkylimidazolium acetate ionic liquids: part 1—analysis, acetylating agent, influence of water, and mechanistic considerations

The acetylating action of ionic liquids frequently used in biomass and polysaccharide processing, namely 1,3-dialkylimidazolium acetates, on cellulose has been studied. Analysis was based on an accurate method to quantify even minute amounts of organic acetates in polysaccharides. The acetylation is caused by impurities in the ionic liquids, specially purified ionic liquids do not show an acetylating effect. 1-Acetylimidazole has been proven to be the actual acetylating agent, and its presence in aged ionic liquids has been confirmed. Formation of the reagent, mechanism of its action—being an acetyl transfer rather than a typical esterification—kinetics of the acetylation and the effect of water in the system are studied in detail. The implications on processing of biomaterials in ionic liquids are discussed as well.

“Egg of Columbus”: Single-step complete removal of chloride impurities from ionic liquids by AgCl deposition on silver electrode

Chloride impurities in ionic liquids (ILs), which can be present even in huge amounts depending on the IL synthetic route, are particularly critical for electrochemical processes; thus, their abatement is often mandatory. However, while their analytical quantification has been the subject of many studies involving a variety of techniques, the so far available processes for their abatement are still unsatisfactory, having low efficiency, and/or involving multiple steps, and/or being far from mild and easily scalable. In this context, like an “egg of Columbus”, a quite simple and safe process for chloride abatement in ILs is proposed, practically coinciding with the electrolytic preparation of a Ag|AgCl electrode. It proceeds in a single step, at room temperature, at very low potentials, with nearly ideal current efficiencies, and with negligible side effects on the electrolyzed IL. The chloride impurities are quantitatively captured and accumulated on the silver wire and eliminated by simply removing the resulting Ag|AgCl electrode from the solution, with no need of subsequent treatments.

Phonon-mediated Casimir interaction between mobile impurities in one-dimensional quantum liquids.

Virtual phonons of a quantum liquid scatter off impurities and mediate a long-range interaction, analogous to the Casimir effect. In one dimension the effect is universal and the induced interaction decays as 1/r3, much slower than the van der Waals interaction ∼1/r6, where r is the impurity separation. The sign of the effect is characterized by the product of impurity-phonon scattering amplitudes, which take a universal form and have been seen to vanish for several integrable impurity models. Thus, if the impurity parameters can be independently tuned to lie on opposite sides of such integrable points, one can observe an attractive interaction turned into a repulsive one.

Determination of Halide Impurities in Ionic Liquids by Total Reflection X-ray Fluorescence Spectrometry

The determination and quantification of halide impurities in ionic liquids is highly important because halide ions can significantly influence the chemical and physical properties of ionic liquids. The use of impure ionic liquids in fundamental studies on solvent extraction or catalytic reactions can lead to incorrect experimental data. The detection of halide ions in solution by total reflection X-ray fluorescence (TXRF) has been problematic because volatile hydrogen halide (HX) compounds are formed when the sample is mixed with the acidic metal standard solution. The loss of HX during the drying step of the sample preparation procedure gives imprecise and inaccurate results. A new method based on an alkaline copper standard Cu(NH3)4(NO3)2 is presented for the determination of chloride, bromide, and iodide impurities in ionic liquids. The 1-butyl-3-methylimidazolium ([C4mim]) ionic liquids with the anions acetate ([C4mim][OAc]), nitrate ([C4mim][NO3]), trifluoromethanesulfonate ([C4mim][OTf]), and bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]) were synthesized via a halide-free route and contaminated on purpose with known amounts of [C4mim]Cl, [C4mim]Br, [C4mim]I, or potassium halide salts in order to validate the new method and standard.

Optical measurements of impurities in room-temperature ionic liquids

The absorption spectra of 1-methylimidazole and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI], mixtures from 0% to 20% mole fraction are reported at ultraviolet to infrared wavelengths. Quantitative measurement of 1-methylimidazole in [EMIM][TFSI] is reported using an isolated 1-methylimidazole absorption feature at 1520cm−1. UV measurements reveal a 1-methylimidazole absorption feature at 270nm and a 260nm feature for [EMIM][TFSI]. Absorption at 280nm is demonstrated to scale with 1-methylimidazole mole fraction in [EMIM][TFSI] and is used to measure 1-methylimidazole mole fractions. Absorption is shown to increase around 240nm upon addition of 1-methylimidazole to [EMIM][TFSI], which preliminary time-dependent density functional theory (DFT) calculations identify as an intermolecular excitation between [EMIM][TFSI] and 1-methylimidazole. We report recommendations for UV and infrared detection schemes for the quantitative detection of 1-methylimidazole in [EMIM][TFSI].

Analysis of refill liquids for electronic cigarettes

To assess levels of nicotine, nicotine degradation products and some specific impurities in commercial refill liquids for electronic cigarettes. We analyzed 20 models of 10 of the most popular brands of refill liquids, using gas and liquid chromatography. We assessed nicotine content, content of the known nicotine degradation products and impurities, and presence of ethylene glycol and diethylene glycol. The nicotine content in the bottles corresponded closely to the labels on the bottles. The levels of nicotine degradation products represented 0-4.4% of those for nicotine, but for most samples the level was 1-2%. Cis-N-oxide, trans-N-oxide, myosmine, anatabine and anabasine were the most common additional compounds found. Neither ethylene glycol nor diethylene glycol were detected. The nicotine content of electronic cigarette refill bottles is close to what is stated on the label. Impurities are detectable in several brands above the level set for nicotine products in the European Pharmacopoeia, but below the level where they would be likely to cause harm.

Homogeneous Nucleation in Water in Microfluidic Channels

It has been an experimental challenge to test the rupture of liquids with homogeneous nucleation of vapor bubbles. Many prior studies suffered from the ubiquitous presence of impurities in liquids or at container surfaces that spontaneously nucleate and grow under tension. Here, we propose a microfluidic approach to eliminate such impurities and obtain homogeneous bubble nucleation. We stretch the liquid dynamically via the interaction between a laser-induced shock and an air-liquid interface in a microchannel. Reproducible observations of the nucleation of vapor bubbles are obtained, supporting our claim of homogeneous nucleation. From comparisons of the distribution of vapor cavities with Euler flow simulations, the nucleation threshold for water at room temperature is predicted to be -60 MPa.

Dynamics and Bloch oscillations of mobile impurities in one-dimensional quantum liquids

We study the dynamics of a mobile impurity moving in a one-dimensional quantum liquid. Such an impurity induces a strong, non-linear depletion of the liquid around it. The dispersion relation of the combined object, called depleton, is a periodic function of its momentum with the period 2πn, where n is the mean density of the liquid. In the adiabatic approximation, a constant external force acting on the impurity leads to the Bloch oscillations of the impurity around a fixed position. Dynamically, such oscillations are accompanied by the radiation of energy in the form of phonons. The ensuing energy loss results in the uniform drift of the oscillation center. We derive exact results for the radiation-induced mobility as well as the thermal friction force in terms of the equilibrium dispersion relation of the dressed impurity (depleton). These results show that there is a wide range of external forces where the (drifted) Bloch oscillations exist and may be observed experimentally.

Understanding the polarity of ionic liquids

The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales α, β and π*, with the dye set Reichardt's Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.

Terahertz response of dipolar impurities in polar liquids: On anomalous dielectric absorption of protein solutions

A theory of radiation absorption by dielectric mixtures is presented. The coarse-grained formulation is based on the wave-vector-dependent correlation functions of molecular dipoles of the host polar liquid and a density structure factor of the solutes. A nonlinear dependence of the dielectric absorption coefficient on the solute concentration is predicted and originates from the mutual polarization of the liquid surrounding the solutes by the collective field of the solute dipoles aligned along the radiation field. The theory is applied to terahertz absorption of hydrated saccharides and proteins. While the theory gives an excellent account of the observations for saccharides, without additional assumptions and fitting parameters, experimental absorption coefficient of protein solutions significantly exceeds theoretical calculations with dipole moment of the bare protein assigned to the solute and shows a peak against the protein concentration. A substantial polarization of protein's hydration shell, resulting in a net dipole moment, is required to explain the disagreement between theory and experiment. When the correlation function of the total dipole moment of the protein with its hydration shell from numerical simulations is used in the analytical model, an absorption peak, qualitatively similar to that seen in experiment, is obtained. The existence and position of the peak are sensitive to the specifics of the protein-protein interactions. Numerical testing of the theory requires the combination of dielectric and small-angle scattering measurements. The calculations confirm that "elastic ferroelectric bag" of water shells observed in previous numerical simulations is required to explain terahertz dielectric measurements.

Ni(tmen)(acac)][B(Ph)4] a probe for the anion basicity of ionic liquids

An optical basicity scale of various ionic liquids (IL) anions has been determined by UV-Vis absorption spectroscopy. The indicator complex [Ni(tmen)(acac)][B(Ph)(4)] (tmen = tetramethylethylendiamine, acac = acetylacetonate) shows to be a sensitive probe as the position of the (3)A(2g)(F) --> (3)T(1g)(F) absorption maximum of square planar to octahedral Ni(2+) shifts distinctly depending on the electron donor ability of the respective ionic liquid anion. If the Lewis basicity of the anion becomes stronger a change to a tetrahedral coordination around Ni(2+) is observed. Here the (3)T(1)(F) --> (3)T(2)(F) and (3)T(1)(F) --> (3)T(1)(P) transitions are helpful for monitoring the IL anion basicity. Evaluating the optical spectra allows ordering the ionic liquids according to rising Lewis basicity: PF(6)(-) < BF(4)(-) < N(Tf)(2)(-) < OTf(-) << HCOO(-) << DCA(-) << CF(3)COO(-) << PO(2)(OEt)(2)(-) << Cl(-). No substantial influence of the ionic liquid counter cation on the Ni(2+) absorption spectra could be detected. In consequence, [Ni(tmen)(acac)][B(Ph)(4)] allows evaluation of the donor power, hence, the Lewis basicity of the ionic liquid anion independent from the IL cation and an optical basicity scale of ionic liquid anions could be successfully established. In addition, [Ni(tmen)(acac)][B(Ph)(4)] turns out to be a sensitive probe to detect even small chloride impurities in ionic liquids which are a commonly encountered contamination in ILs.

Origin and effect of impurities in protic ionic liquids based on 2-methylpyridine and trifluoroacetic acid for applications in electrochemistry

Protic ionic liquids (PILs) based on 2-methylpyridine (2-MPy) and trifluoroacetic acid (TFA) have been synthesized under multiple conditions and with different proportions of their constituents. These PILs present a brown color of variable intensity and the factors responsible for the presence of these impurities have been examined. UV–vis spectroscopy analyses revealed that both TFA and 2-MPy can be thermally degraded during the synthesis process. Distillation of the IL can be used to quickly obtain mixtures without any traces of coloration, but can leads to a severe alteration of the relative proportion of the constituents. This work shows that high-yield syntheses of PILs obtained with different contents in colored impurities can be compared to evaluate the effect of these impurities not only on the electrochemical behavior (on Pt and on GC) but also on the physicochemical properties of interest for PILs as applications in electrochemistry (conductivity, density, and viscosity).

Prediction of Ionic Liquid Properties. I. Volumetric Properties as a Function of Temperature at 0.1 MPa

The prediction of molar volumes and densities of several ionic liquids has been achieved using a group contribution model as a function of temperature between (273 and 423) K at atmospheric pressure. It was observed that the calculation of molar volumes or densities could be performed using the “ideal” behavior of the molar volumes of mixtures of ionic liquids. This model is based on the observations of Canongia Lopes et al. (J. Phys. Chem. B 2005, 109, 3519–3525) which showed that this ideal behavior is independent of the temperature and allows the molar volume of a given ionic liquid to be calculated by the sum of the effective molar volume of the component ions. Using this assumption, the effective molar volumes of ions constituting more than 220 different ionic liquids were calculated as a function of the temperature at 0.1 MPa using more than 2150 data points. These calculated results were used to build up a group contribution model for the calculation of ionic liquid molar volumes and densities with an estimated repeatability and uncertainty of 0.36 % and 0.48 %, respectively. The impact of impurities (water and halide content) in ionic liquids as well as the method of determination were also analyzed and quantified to estimate the overall uncertainty.

IC Determination of Halide Impurities in Ionic Liquids

An ion chromatographic (IC) method has been developed for determination of trace levels of halide impurities in various types of ionic liquids (ILs). The advantage of this method is that all relevant halide species can be measured in a single chromatographic analysis. Separation of halides was performed on a Dionex AS9-HC column using an eluent consisting of 20 mM NaOH and 10% (v/v) acetonitrile, delivered at 1.5 mL min−1. Using this eluent, fluoride, chloride and bromide were well resolved from each other, but iodide was co-eluted with tetrafluoroborate (BF4−) present as a counter-anion in tetrafluoroborate-based ILs. The same eluent was also used successfully for the determination of halides in highly hydrophobic ILs, such as those based on bis-(trifluoromethanesulfonyl)imide (TFSI−) and bis-perfluoroethylsulfonylimide (BETI−). In this case, 50% (v/v) acetonitrile aqueous was needed to dissolve the sample before injection, and this did not adversely affect the separation. Detection limits in the measured solution were 0.1, 0.2 and 1.0 ppm for chloride, bromide and iodide, respectively, by conductivity detection, and 0.02 ppm for iodide by UV detection.