Solubility In Toluene Research Articles

Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal

A novel method of removal of volatile organic compounds (VOCs) using the ionic liquid [Bmim][NTf2] as an absorbent is developed as a contribution to dealing with recent severe smog incidents in China. The effects of concentration, temperature and flow rates on the ability of [Bmim][NTf2] to absorb VOCs were studied using toluene as a model volatile organic pollutant. The potential of the use of [Bmim][NTf2] as an absorbent for VOCs is shown by the solubility of toluene in the ionic liquid; the absorptivity of the ionic liquid for toluene; and the fact that absorbed toluene can be removed easily from [Bmim][NTf2], permitting recycle of the ionic liquid in multiple reuse phases. The solubility of toluene in [Bmim][NTf2] is 61.5% at 20°C and atmospheric pressure; the highest absorptivity of [Bmim][NTf2] for toluene is 98.3%, achieved at a toluene concentration of 300ppm and a flow rate of 50mLmin−1 at 20°C; and the absorptivity of the ionic liquid is>94% over a wide range of conditions. The ionic liquid can be recovered and recycled in the absorption process at least five times, reducing the reagent cost in the VOC removal process.

SYNTHESIS AND OPTICAL PROPERTIES OF CAMPHOR-SABSTITUTED TETRAPYRAZINOPORPHYRAZINES

The synthesis of the complexes of Cu, Ni, Co, Pd, Sn, Hg of 1',7',7'-trimethylbicyclo[2.2.1]heptano-[2',3'-b]-2,3-pyrazinoporphyrazine for new materials for variety of potential applications is described. Metallic complexes were synthesized by the template cyclotetramerization of dicarbonitrile with metal chlorides at temperature 140-150 ºС for 20 min. Ammonium molybdate tetrahydrate was used as a catalyst. The products were purificated by chromatography on silica gel (eluent -chloroform). Complexes of Pd, Sn and Hg were synthesized for the first time. The metallocomplexes of camphor-substituted tetrapyrazinoporphyrazine are crystalline substances of dark blue color, not fusible up to 300 ° C, which have good solubility in chloroform, toluene, ethanol, acetone, DMF, acetic and trifluoroacetic acids. The chemical structures of the complexes of Cu, Ni, Co, Pd, Sn, Hg of 1',7',7'-trimethylbicyclo[2.2.1]heptano-[2’,3’-b]-2,3-pyrazinoporphyrazine obtained in this study were characterized by proton nuclear magnetic resonance and mass spectrometry. The absence of impurity signals in the 1H NMR spectra indicates a high degree of purity of the compounds obtained. For copper, nickel and cobalt complexes, a good correlation was found between the experimental and literature data on the chemical shifts of protons in 1H NMR spectra. Optical properties of the synthesized complexes were studied. The electronic absorption spectra of the complexes in their chloroform, DMF, acetic acid and sulfuric acid solutions were obtained. In organic solvents the typical B band (Soret band, around 400 nm) and Q band (in 600-700 nm region) of phthalocyanines were identified in this study. Complexes of Pd, Sn and Hg in their sulfuric acid solutions are non-stable. The influence of the chemical structure of metalic complexes and solvents on the optical properties was studied. Emission properties of the synthesized complexes of Pd and Hg in their chloroform and DMF solutions were analyzed. Hg-porphyrazine has very intensive fluorescence. The solution has blue color and red fluorescence at common condition.Forcitation:Kuvshinov G.V., Ziyadova T.M., Kuvshinova S.A., Koifman O.I. Synthesis and optical properties of camphor-sabstituted tetrapyrazinoporphyrazines. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 60-67.

Comparative Study of the Properties of the Coal Extractive and Commercial Pitches

Three extractive pitches were produced by using thermal dissolution of the medium-ranked coals at 380 °C in anthracene oil. The empirical properties such as the chemical composition, solubility in quinoline and toluene, softening point, and content of carcinogenic polycyclic hydrocarbons, and also molecular and structural parameters of the extractive pitches were characterized in comparison with three commercially available pitches, including typical coal-tar pitch, petroleum-derived pitch, and blended pitch derived from the mixture of coal tar with petroleum feedstock. The molecular and structural properties of pitches were studied using FTIR, 1H and 13C NMR, and XRD techniques. It was shown that the average molecule of the extractive pitches was composed of predominantly aromatic rarely substituted pericondensed nuclei, such as that in coal-tar pitch. The spatial structures of both the extractive and reference pitches consisted of predominantly disordered carbon matter with a small amount of rather ordered nanosized “graphite-like” stacks. In terms of the technical specifications, the extractive pitches irrespective of the coal used met the requirements for the pitch binder and resembled commercial blended petro-coal-tar pitch. A remarkable merit of the extractive pitches compared to coal-tar pitch was low carcinogenicity (two to three times as low).

Effect of fatty acids complexed with polyethyleneimine on the flow curves of TiO2 nanoparticle/toluene suspensions

A series of polyethyleneimine (PEI)–fatty acid complexes using oleic acid (OA), isostearic acid (ISA), and stearic acid (SA) were prepared through a simple process. While PEI was not soluble in toluene, the complex with OA and ISA became soluble when its additive content was greater than 5 mol% based on the ethyleneimine (EI) unit of PEI. PEI–SA had similar solubility in toluene when more than 5 mol% of SA was added; however, the complex precipitated when the additive ratio of SA was increased to 40 mol%. The effect of fatty acid of PEI complexes on their TiO2 nanoparticle adsorption properties and the flow curves of TiO2 nanoparticle/toluene suspension was then studied using PEI complexed with 30 mol% of fatty acids. Surprisingly, while PEI–OA and PEI–ISA complexes effectively adsorbed on TiO2 nanoparticles until saturation, the amount of adsorbed PEI–SA increased continuously. Comparing the flow curves of TiO2/toluene suspensions under 1.4 mg/m2 addition of PEI–fatty acid complexes, where PEI–OA and PEI–ISA were under saturated adsorption, it was confirmed that PEI–OA effectively stabilizes TiO2 nanoparticles in toluene without imparting thixotropic properties up to 30 vol%, while the suspensions with PEI–SA and PEI–ISA were solidified at lower volume contents and had high thixotropic properties.

Microstructure and performance of carbonization products of component from soft coal pitch

Pitch is constituted of aromatic hydrocarbon, which is one kind of organic liquid with high viscosity. The soft coal pitch was divided into different group components by solvent extraction, and the different fractions of soft coal pitch were carbonized separately. The relationship between the microstructures of carbonization products and the chemical compositions of group components was investigated in this paper. Results show that the structure and morphology of the carbonization products from pitch were significantly influenced by the chemical composition of the group components. The main microstructure of the toluene soluble (TS) fraction-derived carbonization products is streamline and partial regional type. The microstructure of products from toluene insoluble (TI) fraction is mosaic and regional type. The structure of toluene insoluble-quinoline soluble (TI-QS) fraction-derived carbonization product is mainly streamline type. Nevertheless, the carbonization product from quinoline insoluble (QI) fraction is constituted with isotropy micron grade isotropic particles.

Thermodynamic Stability Analysis of Tolbutamide Polymorphs and Solubility in Organic Solvents

Melting temperatures and enthalpies of fusion have been determined by differential scanning calorimetry (DSC) for 2 polymorphs of the drug tolbutamide: FIH and FV. Heat capacities have been determined by temperature-modulated DSC for 4 polymorphs: FIL, FIH, FII, FV, and for the supercooled melt. The enthalpy of fusion of FII at its melting point has been estimated from the enthalpy of transition of FII into FIH through a thermodynamic cycle. Calorimetric data have been used to derive a quantitative polymorphic stability relationship between these 4 polymorphs, showing that FII is the stable polymorph below approximately 333 K, above which temperature FIH is the stable form up to its melting point. The relative stability of FV is well below the other polymorphs. The previously reported kinetic reversibility of the transformation between FIL and FIH has been verified using in situ Raman spectroscopy. The solid-liquid solubility of FII has been gravimetrically determined in 5 pure organic solvents (methanol, 1-propanol, ethyl acetate, acetonitrile, and toluene) over the temperature range 278 to 323 K. The ideal solubility has been estimated from calorimetric data, and solution activity coefficients at saturation in the 5 solvents determined. All solutions show positive deviation from Raoult's law, and all van't Hoff plots of solubility data are nonlinear. The solubility in toluene is well below that observed in the other investigated solvents. Solubility data have been correlated and extrapolated to the melting point using a semiempirical regression model.

Experimental Study on the Absorption of Toluene from Exhaust Gas by Paraffin/Surfactant/Water Emulsion

A new paraffin/surfactant/water emulsion (PSW) for volatile organic compounds (VOCs) controlling was prepared and its potential for VOCs removal was investigated. Results indicated that PSW-5 (5%, v/v) provided higher toluene absorption efficiency (90.77%) than the other absorbents used. The saturation pressure, Henry’s constant, and activity coefficient of toluene in PSW-5 were significantly lower than those in water, and toluene solubility (1.331 g·L−1) in the PSW-5 was more than 2.5 times higher than the value in water. Several factors potentially affecting the toluene absorption efficiency were systematically investigated. The results suggested that concentration and pH of PSW, absorption temperature, and gas flow rate all had a strong influence on the toluene absorption, but the inlet concentration of toluene had little effect on the toluene absorption. There were different absorbing performances of PSW-5 on different VOCs, and the ketones, esters, and aromatics were more easily removed by the PSW-5 than the alkanes. Regeneration and reuse of the PSW were possible; after 3 runs of regeneration the absorption efficiency of PSW-5 for toluene also could reach 82.42%. So, the PSW is an economic, efficient, and safe absorbent and has a great prospect in organic waste gas treatment.

Solubility of CO2 in [1-n-butylthiolanium][Tf2N]+toluene mixtures: liquid-liquid phase split separation and modelling.

Carbon dioxide has been shown to be an effective antisolvent gas for separating organic compounds from ionic liquids (ILs) by inducing a liquid-vapour to liquid-liquid-vapour transition. Using carbon dioxide, toluene can be separated from imidazolium, phosphonium and pyridinum cation-based ILs with the bis(trifluoromethylsulfonyl)imide anion, which is relatively hydrophobic and has a high toluene solubility. A new IL with relatively low viscosity is tested here for the same toluene separation process: 1-n-butylthiolanium bis(trifluoromethylsulfonyl)imide. Carbon dioxide solubility in binary and ternary systems containing toluene and 1-n-butylthiolanium bis(trifluoromethylsulfonyl)imide is measured at 298.15 and 313.15 K up to 7.4 MPa. Solubility behaviour in this IL is similar to imidazolium-based ILs with the same anion. However, phase split pressures are lower when 1-n-butylthiolanium bis (trifluoromethylsulfonyl)imide is used instead of 1- n-hexyl-3-methylimidazolium bis(trifluoromethylsu- lfonyl)imide at the same conditions of temperature and initial composition of toluene in the IL. Solubility data are modelled with the conductor-like screening model for real solvents combined with the Soave-Redlich-Kwong equation of state, which provides good qualitative results.

Synthesis and characterization of Luffa cylindrica fatty acids-based alkyd resins

The work reports on preparation of three grades of alkyd resins using a two-stage alcoholysis-polyesterification method. Phthalic anhydride, glycerol and Luffa cylindrica seed oil were used in the formulation of the alkyds. The oil was extracted with n-hexane and 30.30 % was obtained. The fatty acids and physicochemical analyses of L. cylindrica seed oil revealed 77.78 % unsaturated fatty acids with linoleic acid (50.25 %), oleic acid (27.30 %), palmitic acid (13.40 %), and stearic acid (6.38 %) being the most abundant; and iodine value, 153 mg I2/g respectively. Properties of the alkyds having oil content of 40 % (I), 50 % (II) and 60 % (III) were evaluated. The acid value was observed to decrease as the reaction progressed. FTIR spectra of the alkyds revealed ester linkages and olefenic hydrogen stretch at 1737.92–1734.06 and 3064.99–3007.12 cm−1 respectively. Evaluation of prepared alkyds by determination of acid values, iodine values, solubility in xylene, toluene and acetone; resistance of dry film to acid, alkali and water; scratch and gouge film hardness and drying time revealed that L. cylindrica seed oil is a potential raw material for the coatings industry.

Hyperbranched polymer-protected gold nanoparticles well-dispersed in different organic solvents: preparation and their catalytic applications to 4-nitrophenol reduction

A series of spherical gold nanoparticles (AuNPs) stabilized by amphiphilic hyperbranched polymers, which have a hydrophilic hyperbranched polyethylenimine core and a hydrophobic shell formed by many long acidamide chains such as saturated palmitamide, octadecanamide, and unsaturated oleamide chains, were prepared by chemical reduction. The effect of the kinds and the ratio of the aliphatic chain in amphiphilic polymers, the amount of the amphiphilic polymers, and the storage time on their size, solubility, and stability in chloroform, toluene, petroleum ether, and n-butyl acetate was investigated by TEM, UV-vis. The results revealed that a high-concentration polymer with a double bond can greatly improve the organic solubility and stability of the AuNPs in the toluene, petroleum ether, and n-butyl acetate. All the AuNPs in different solvents could be used as highly efficient catalysts for the biphasic catalytic reduction of 4-nitrophenol. The effect of the concentration of AuNPs and the capping polymers, the volume of organic phase, and temperature on the turnover number (TON) values of AuNPs is also studied. Their TON values could be enhanced by the AuNPs capped with more polymers or selecting a good solvent. The maximum TON values of the AuNPs in different solvents are about 5040 which has never been reported in the heterogeneous catalytic reduction of 4-nitrophenol.

Solubility enhancement of producer gas tar compounds in water using sodium dodecyl sulfate as a surfactant

The overall goal of this study was to improve the solubility of tar compounds in water using a surfactant, sodium dodecyl sulfate (SDS). The solubility experiments were performed using 100-ml media bottles. Benzene, toluene, ethylbenzene, styrene, and p-xylene were used as model tar compounds because these compounds are sparingly soluble in water. The solubility of tar compounds was measured using UV/VIS spectrophotometer. Statistical analysis showed that solubilities of tar compounds improved significantly (p<0.0001) using SDS above the critical micelle concentration. Experimental results showed that the solubility of benzene, toluene, ethylbenzene, styrene and p-xylene increased 4 to 14, 9 to 33, 19 to 69, 18 to 83 and 29 to 135 fold, respectively, as SDS concentration increased from 0, i.e., water as control to 15, 30, 45 and 60g/L at solvent temperature of 20°C. Results also showed that solubilities of benzene, toluene and ethylbenzene decreased as the solvent temperature increased.

Hydrovisbreaking of vacuum residue from Russian Export Blend: influence of brown coal, light cycle oil, or naphtha addition

AbstractDemand for high-value petroleum products is increasing and crude oils and their distillation products are becoming heavier. The thermal cracking of a vacuum residue (VR) from REB (Russian Export Blend) crude oil was carried out in an autoclave. LCO (light cycle oil), naphtha, and brown coal (BC) were added with the aim of studying their effect on the final products composition. The elemental analysis (%C, %N, %H, %S) was performed and dynamic viscosity, density, GC of gases (“Refinery Gas Analysis”), solubility in hexane and toluene, and simulated distillation were examined in raw materials, gaseous, and liquid products. As anticipated, due to its high aromatics content, the addition of LCO proved the best option, obtaining the highest yield of lighter liquids. The naphtha addition resulted in a slight increment of heavier products in the gaseous phase and higher yields to solids. The literature does not contain any extensive studies of the addition of BC to VR in the hydrovisbreaking process. The addition of BC resulted in an increment in the yield of the gaseous product and assumed the highest relative total consumption of hydrogen during the reaction.

Incompatible Liquids in Confined Conditions

In applications involving organic vapour, the performance of high surface area carbons is often challenged by water vapour in the atmosphere. Small angle neutron scattering (SANS), through its ability to distinguish between different components by means of contrast variation, is ideally suited to investigating the behaviour of adsorbed layers in simultaneous contact with a mixed vapour phase. Even at high relative humidity (RH), water alone forms a discontinuous film composed of clusters on the surface of the oxidized microporous carbon used for these studies. When toluene is also present, all the available carbon surface is wetted. Toluene and water adsorb as a single phase already at RH 11.5%, and the concentration of water present in the adsorbed phase is as high as 2.9 wt.%, far above its solubility in bulk toluene (0.033 wt.% at 25 deg C). At RH 87% the concentration of water in the adsorbed phase is four times higher, approximately 12 wt.%. The recently proposed mechanism of anchoring of the water by the aromatic molecules may provide an explanation for this phenomenon.

A modified continuous flow apparatus for gas solubility measurements at high pressure and temperature with camera system

A continuous flow apparatus with a camera system was modified for high-pressure gas–liquid equilibrium measurements. The continuous flow method is suitable for phase equilibrium measurements of heat-sensitive materials, such as heavy oils and bio-based feedstocks, which are refined in hydroprocesses at high temperatures and pressures. Benefits of the modified apparatus are a short residence time of a sample in the heated zone and no sampling is required. In contrast, the static method is usually impractical with the heat-sensitive materials due to the long residence time of sample in the equilibrium cell. In this study, the continuous flow apparatus and the measurement method was adopted and validated. The validation was conducted by measuring hydrogen solubility in toluene and n-hexadecane at high temperatures and pressures (T=461–575K, P=5–10MPa) and comparing the results with the literature values. Relative average pressure deviation was found to be 3.8% for measurements of this work when the PC-SAFT equation of state was optimized against literature values while the relative average pressure deviations for the literature data sets varied from 0.9% to 4.7%. Thus, the quality of measurements was shown to be excellent. In addition, hydrogen solubility was also measured in n-octadecane in order to obtain new data for this system. All measured systems were modeled with the PC-SAFT and the original and modified Peng–Robinson equations of state in order to simplify the validation of the measurement method and to compare the performance of the selected models. PC-SAFT was found to predict phase behavior of the systems precisely whereas the predictions of the Peng–Robinson modifications were less precise.

(Invited) Double Salt Ionic Liquids Prepared by Mixing Partially Miscible Ionic Liquids: Tuning the Solubility of Lipophilic Molecules

Double Salt Ionic Liquids (DSILs) were prepared by mixing 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) and trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide ([P66614][NTf2]) in their miscible range: [C2mim]x[P66614](1-x)[NTf2] (0 ≤ x ≤ 0.29). 1H NMR, 19F NMR, and FT-IR spectroscopic studies indicated that the [NTf2]-anions preferentially interact with the [C2mim]+cations. Solubility studies showed that solutes with long alkyl chains (e.g., heptane, methyl palmitate), which have good solubility in [P66614][NTf2] but are not totally miscible, have tunable solubility in the DSILs and the presence of even minor amounts of [C2mim]+significantly decreases their solubility. However, the solubilities of benzene, toluene, 1-octanol, and poly(ethylene glycol) (PEG-300) in [C2mim]x[P66614](1-x)[NTf2] were controlled by their miscibility with [P66614][NTf2], and can’t be tuned by changing the ion concentrations within the miscibility range.

Thermal Conversion Characteristics of Coal Tar Soft Pitch at Atmospheric and Elevated Pressures

Coal tar soft pitch (CTSP) used as raw material of preparing needle coke was heat-treated at 460, 480 and 500 °C for different holding time under the pressure of 0 MPa and 0.25 MPa. The changes of group compositions such as toluene solubles (TS), toluene insolubles-quinoline solubles (TI-QS) and quinoline insolubles (QI) were mainly studies during the thermal conversion of the CTSP. The microstructure morphologies of some calcined cokes were characterized by scanning electron microscope (SEM). The results showed that the thermal conversion of the CTSP had the features of consecutive reaction, and the pressure could accelerate the conversion rate of TS and TI-QS and the formation rate of QI. The calcined coke derived from the semi-coke obtained at atmospheric pressure exhibited better and longer streamlined fiber structures than that of the semi-coke obtained at elevated pressure, while the latter possessed more compact carbon structures than the former.

Precipitation of Asphaltenes and Resins at the Toluene–Silica Interface: An Example of Precipitation Promoted by Local Electrical Fields Present at the Silica–Toluene Interface

Adsorption and desorption of asphaltenes and resins occurring at the silica–toluene interface were used as a tool to investigate phase separation or precipitation promoted by the surface. Adsorption isotherms for this system were obtained as usual, employing commercial silica plates immersed in toluene solutions. After the adsorption of the sample (asphaltenes, asphaltene subfraction A2, resins I, and resins II), the plate was removed, contacted with and retracted from toluene to remove trapped solution, and then immersed again in fresh toluene to measure the desorption. In all cases, the amount desorbed was either insignificant or a small fraction of the amount expected. This could be analyzed in terms of precipitation at the interface promoted by local electrical fields present at the silica–toluene interface; these fields promote molecular polarization, dispersion interactions, and piling up, leading to precipitation. As a result, when the plate with the adsorbed precipitate (material of very low solubility in toluene) is contacted with fresh toluene, desorption is either insignificant or very low. The combine effects of the local electrical fields, molecular polarization, and dispersion interactions are so effective that resin precipitation at the above interface was also obtained. These ideas were found coherent with preliminary atomic force microscopy (AFM) measurements performed on asphaltenes deposited on a glass surface.

Oxidative desulfurization of fuels catalyzed by ammonium oxidative-thermoregulated bifunctional ionic liquids

Abstract A series of developed ammonium oxidative-thermoregulated bifunctional ionic liquids (ILs) catalysts have been synthesized. The structures of these task-specific ionic liquids (TSILs) are characterized by FT-IR and 1H NMR. The thermoregulated properties of ILs in aqueous and common organic solvent are investigated. The prepared ionic liquid has the cloud point (CP) in aqueous, and has the minimum solubility in toluene. The ionic liquid has the corresponding critical solution temperature (CST) in toluene/n-octane or n-dodecane mixed solvents, which makes the system with the thermoregulated feature of “homogeneous at high temperature, heterogeneous at low temperature”. The developed thermoregulated system has been used for catalytic H2O2 oxidative desulfurization of model fuels to achieve an integration of homogeneous catalysis and heterogeneous separation. The recycle of the ionic liquid catalyst is easily achieved. The desulfurization rate only keeps a gradually slight drop during the recycles of the catalyst.

Experimental Investigation on the Solubility of Oxygen in Toluene and Acetic Acid

By using the dual vessel equilibrium method, the solubility of oxygen in toluene and acetic acid was experimentally investigated with pressure ranging from 0.1 to 1.0 MPa at temperatures from 293.1 to 383.1 K. The results show that the oxygen solubility either in toluene or in acetic acid increases with a rise in temperature. On the basis of the experimental data, Henry coefficients were derived and expressed as a function of temperature. At the same temperature, Henry coefficient for the oxygen–toluene system is lower than that for the oxygen–acetic acid system. Through analysis of the Gibbs energy (ΔG0), partial molar enthalpy (ΔH0), and the partial molar entropy (ΔS0) of the solvation, we can know that solubilization of oxygen either in toluene or in acetic acid is an endothermic process. To correlate the experimental data, the Peng–Robinson equation of state with the quadratic mixing rule was used for the two systems.

Thermodynamics of risperidone and solubility in pure organic solvents

The solid–liquid solubility of the thermodynamically stable form I of the drug risperidone has been determined by a gravimetric method in nine pure organic solvents in the temperature range 278.15–323.15K. The melting temperature and associated enthalpy of fusion of risperidone form I has been determined by differential scanning calorimetry (DSC) to be 442.38K and 43.94kJmol−1, respectively. The heat capacity of the solid form I and the melt have been determined over a range of temperatures by temperature-modulated DSC, and extrapolated data has been used to calculate the Gibbs energy, enthalpy and entropy of fusion from ambient temperature up to the melting point. The ideal solubility within a Raoult's law framework is obtained from the Gibbs energy of fusion, and the solution activity coefficient at equilibrium in the nine solvents quantified. Solutions in all solvents exhibit positive deviation from Raoult's law, with the highest solubility (closest to ideality) in toluene, an aprotic apolar solvent. The solubility curves plotted in a van’t Hoff graph show non-linear behaviour and are well-approximated by a second order polynomial.