Cyclohexane Concentration Research Articles

A novel unspecific peroxygenase from Agaricus bisporus var. bisporus for biocatalytic oxyfunctionalisation reactions

Unspecific peroxygenases (UPOs) represent an emerging class of catalysts for the selective oxyfunctionalisation of CH- and C = C groups. Until now, only a few UPOs have been characterised. In this study, we report a new peroxygenase identified from the Unspecific Peroxygenase Database. The UPO from Agaricus bisporus var. bisporus (AbvbUPO) has been heterologously expressed in Aspergillus niger and initially characterised with respect to its basic biochemical features. Furthermore, its catalytic properties were evaluated with enzymatic cascade reactions of choline oxidase (AnChOx) and AbvbUPO, which the AnChOx provided H2O2 necessary via reductive activation of oxygen in situ. Three types of oxyfunctionalizations, such as hydroxylation of ethylbenzene, epoxidations of styrene and cyclohexene, sulfoxidations of methyl phenyl sulfide and phenyl vinyl sulfide, were successfully achieved. We also investigated the activity of AbvbUPO on fatty acids in some more detail. The experimental results show that Under the above conditions, AbvbUPO had the higher activity for cyclohexene epoxidation and sulfonation of sulfide substrates. The concentration of epoxy cyclohexane was 2.91 mM, and the concentration of methyl phenyl sulfoxide was 3.69 mM. The regioselectivity of AbvbUPO was ω-1 bonds position of linear saturated fatty acid. All in all, AbvbUPO exhibits some interesting differences which may put the basis for further understanding of the factors determining peroxygenase selectivity.

Photoelectrochemical Epoxidation of Cyclohexene on an α-Fe2O3 Photoanode Using Water as the Oxygen Source.

This study developed a safe and sustainable route for the epoxidation of cyclohexene using water as the source of oxygen at room temperature and ambient pressure. Here, we optimized the cyclohexene concentration, volume of solvent/water (CH3CN, H2O), time, and potential on the photoelectrochemical (PEC) cyclohexene oxidation reaction of the α-Fe2O3 photoanode. The α-Fe2O3 photoanode epoxidized cyclohexene to cyclohexene oxide with a 72.4 ± 3.6% yield and a 35.2 ± 1.6% Faradaic efficiency of 0.37 V vs Fc/Fc+ (0.8 VAg/AgCl) under 100 mW cm-2. Furthermore, the irradiation of light (PEC) decreased the applied voltage of the electrochemical cell oxidation process by 0.47 V. This work supplies an energy-saving and environment-benign approach for producing value-added chemicals coupled with solar fuel generation. Epoxidation with green solvents via PEC methods has a high potential for different oxidation reactions of value-added and fine chemicals.

Light and Solvent Effect on Isomerization and Excimer Formation of Pyrene—Schiff Base Conjugate Sensing Aromatic Analytes

AbstractPyrene is a fluorescent polycyclic aromatic compound and it will be fascinating whether its excimer complex can be used for sensing of aromatic analytes. So, (E)‐3,4,5‐tris(dodecyloxy)‐N'‐(pyren‐1‐ylmethylene) benzohydrazide (P@M) is synthesized. The E (trans)‐isomer of P@M exhibits bright fluorescence for excimer formation in non‐aromatic solvents for closeness of pyrene moieties of E‐P@M. Upon photo‐irradiation with λ = 254 nm E‐P@M changes to Z‐P@M (cis ‐isomer) at 10−4 M concentration in methyl cyclohexane (MCH) yielding diminished PL‐intensity. Interestingly, upon photo irradiation with λ = 365 nm, the Z‐isomer of P@M reverts to E‐isomer indicating that, E‐Z isomerization of P@M is reversible in nature. The UV–vis absorption band at 370 nm of E‐P@M in MCH at 10−4 M shifts to 344 nm for its Z‐isomer formation. The thick supramolecular aggregated morphology of E‐P@M changes to flowery needle like morphology after photo irradiation with λ = 254 nm. The fluorescent emission of E‐P@M in MCH is quickly quenched on addition of different aromatic analytes through both static and dynamic path way. In solid state E‐P@M also sense aromatic vapors efficiently via fluorescence quenching.

Investigation of cyclohexene thermal decomposition and cyclohexene + OH reactions

Cyclohexene is a common intermediate in the oxidation of cyclohexane and alkyl-substituted cyclohexanes. It also plays an important role in the formation of polycyclic aromatic hydrocarbons (PAHs) by providing a route for the first aromatic ring. Two types of reactions are highly important in cyclohexene kinetics, i.e., H-abstraction by OH radicals and cyclohexene thermal decomposition. In this work, we have investigated these two reactions experimentally by employing sensitive UV diagnostics of OH radicals and 1,3-butadiene. We conducted rate coefficient measurements of cyclohexene + OH reaction (k1) over 933–1259 K and 1–4 bar using a narrow-linewidth UV absorption diagnostic of OH radicals near 306.67 nm. The carefully designed test conditions minimized the influence of secondary reactions such as cyclohexene thermal decomposition. Our determined OH + cyclohexene high-temperature rate coefficients show a positive temperature dependence and a negligible pressure dependence. Our rate values may be fitted with a two-parameter Arrhenius expression (units of cm3molecule−1s−1):k1=1.28×10−10e(−1225T)We also investigated channel-specific competition in OH + cyclohexene reaction. H-abstraction by OH from allylic (kc), alkylic (kb), and vinylic (ka) CH bonds contributes roughly 60%, 35%, and 5% over our temperature range. Our determined kc agrees excellently with literature rate coefficient of H-abstraction from the allylic site of 1-butene.We studied cyclohexene thermal decomposition reaction (k2) by tracing the product 1,3-butadiene near 212.5 nm over 1092–1361 K and 0.82–1 bar. Compared to literature works, our highly sensitive UV diagnostic of 1,3-butadiene enabled time-resolved measurements with low cyclohexene concentration, which guaranteed nearly isothermal conditions despite reaction endothermcity. Our measured rate coefficients may be expressed as (unit of s−1):k2=3.68×1014e(−31,562T)We implemented our determined rate coefficients (k1 and k2) in a literature cyclohexene kinetic model and also updated the 1,3-butadiene sub-mechanism. The updated model shows improved predictions of measured ignition delay times of cyclohexene.

Mononuclear Oxidovanadium(IV) Complexes with BIAN Ligands: Synthesis and Catalytic Activity in the Oxidation of Hydrocarbons and Alcohols with Peroxides

Reactions of VCl3 with 1,2-Bis[(4-methylphenyl)imino]acenaphthene (4-Me-C6H4-bian) or 1,2-Bis[(2-methylphenyl)imino]acenaphthene (2-Me-C6H4-bian) in air lead to the formation of [VOCl2(R-bian)(H2O)] (R = 4-Me-C6H4 (1), 2-Me-C6H4 (2)). Thes complexes were characterized by IR and EPR spectroscopy as well as elemental analysis. Complexes 1 and 2 have high catalytic activity in the oxidation of hydrocarbons with hydrogen peroxide and alcohols with tert-butyl hydroperoxide in acetonitrile at 50 °С. The product yields are up to 40% for cyclohexane. Of particular importance is the addition of 2-pyrazinecarboxylic acid (PCA) as a co-catalyst. Oxidation proceeds mainly with the participation of free hydroxyl radicals, as evidenced by taking into account the regio- and bond-selectivity in the oxidation of n-heptane and methylcyclohexane, as well as the dependence of the reaction rate on the initial concentration of cyclohexane.

Numerical investigation on Rayleigh-Bénard convection of cyclohexane-oxygen mixture near its maximum density in a rectangular container

The oxidation of cyclohexane is an important route in the chemical industries for producing cyclohexanol, cyclohexanone, plasticizers, surfactants and so on. However, it will be in danger of explosion once the concentration of cyclohexane in the mixture exceeds the explosion limit. Therefore, it is necessary to research the temperature distribution and flow characteristics in Rayleigh-Bénard (RB) convection of cyclohexane/oxygen mixture to avoid the potential hazard of deflagration. In this paper, a set of three-dimensional simulations were performed to understand RB flow characteristics of cyclohexane/oxygen mixture near the maximum density in a rectangular container with an aspect ratio of 2. Rayleigh (Ra) number ranges from 2 × 103 to 6 × 105. Results show that the density inversion has a notable influence on RB convection of cyclohexane/oxygen mixture. The critical Rayleigh numbers for the onset of stable flow and for the oscillatory flow show an upward tendency with increasing density inversion parameter (Θm). When Θm is small, the flow occurs in the whole cavity. When Θm is large, the fluid layer near the top wall is static in the region. Multiple flow states and their evolutions are obtained at various Θm. The heat transfer ability is enhanced with increasing Ra, while it weakens with increasing Θm.

VALIDASI METODE UJI SENYAWA CYCLOHEXANE DI UDARA LINGKUNGAN KERJA DENGAN BERBAGAI MODIFIKASI METODE SECARA GAS CHROMATOGRAPHY MASS SPECTROMETRY

Determination of the cyclohexane compound used refers to the National Institute of Occupational Safety and Health (NIOSH) method number 1500. Validation of the determination of cyclohexane in air samples of the work environment needs to be done due to modifications between them in different columns, glass columns 3.0 mx 2-mm , 20% SP-2100 on 80/100 mesh Supelcoport becomes Rtx-5MS column, the injector temperature difference, column temperature, detector temperature, and the test material used is cyclohexane pa to cyclohexane for gas chromatography, differences in measurements using FID detectors to spectrometer detectors mass. This experiment aims to ensure the performance of the cyclohexane determination method in the air sample of PT UP's work environment by gas chromatography mass spectrometry (GCMS) in accordance with the accepted method requirements set by PT. Unilab Prime. If all parameters meet the acceptance requirements, then this method can be used for routine analysis. Validation parameters carried out include linearity test, instrument detection limit (LDI), quantitation limit (LK), precision,accuracy, and strength of the method (robustness) using gas spectrometer mass chromatography. Based on the experimental results obtained by the value of the correlation coefficient linearity test (r) of 0.9998,% SBR for the precision test of 1.64%,% recovery obtained range of 89.26% - 105.35%. The instrument detection limit value is 0,0003mg / mL, the quantization limit is 0.0010mg / mL. Testing the strength parameters of the method (Robustness) produces cyclohexane concentrations in accordance with the accepted requirements of the working range of cyclohexane 0.5000mg / mL. Based on the test results obtained the performance of the cyclohexane determination method that has undergone modification in a sample of working air environment by gas chromatography mass spectrometry (GCMS) in accordance with the requirements set by thecompany so that it can be used for routine analysis in the PT Unilab Perdana environmental laboratory.

Structural transition of reverse cylindrical micelles to reverse vesicles by mixtures of lecithin and inorganic salts

HypothesisThe transformation from reverse micelles to reverse vesicles is influenced by electrostatic interactions between lecithin headgroups and inorganic salts. The electrostatic interactions are expected to influence molecular geometry of lecithin, resulting in a reduction in critical packing parameter (p). Hence, it should be possible to drive structural transitions of reverse self-assembled structures by addition of inorganic salts to lecithin solutions. ExperimentsStructural transitions of reverse micelles and reverse vesicles were formulated including lecithin and inorganic salts as a function of concentration in cyclohexane. A systematic study was performed using inorganic salts with the different valences of the cations such as Li+, Ca2+, and La3+. To probe the nanodomain structures from the lecithin/salt mixtures, small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used. FindingsAdding salts to lecithin solutions induced the systematic transformation of reverse self-assembled structures from reverse spherical micelles to reverse cylindrical micelles and finally to reverse vesicles. The transformation was also correlated with interactions between lecithin headgroups and salts, that is, Li+ < Ca2+ < La3+. In addition, a water-soluble dye such as rhodamine B (RB) can be readily encapsulated into reverse micelles and vesicles, indicating that they are potentially useful for controlled solute delivery.

Quantitative volatile organic compound sensing with liquid crystal core fibers

SummaryPolymer fibers with liquid crystals (LCs) in the core have potential as autonomous sensors of airborne volatile organic compounds (VOCs), with a high surface-to-volume ratio enabling fast and sensitive response and an attractive non-woven textile form factor. We demonstrate their ability to continuously and quantitatively measure the concentration of toluene, cyclohexane, and isopropanol as representative VOCs, via the impact of each VOC on the LC birefringence. The response is fully reversible and repeatable over several cycles, the response time can be as low as seconds, and high sensitivity is achieved when the operating temperature is near the LC-isotropic transition temperature. We propose that a broad operating temperature range can be realized by combining fibers with different LC mixtures, yielding autonomous VOC sensors suitable for integration in apparel or in furniture that can compete with existing consumer-grade electronic VOC sensors in terms of sensitivity and response speed.

The physicochemical and catalytic properties of clay extrudates in cyclization of citronellal

Four clay materials, namely, bentonite, bleaching earth, attapulgite and sepiolite, were shaped into the cylindrical body by extrusion. Clays were characterized in depth by TEM, SEM-EDX, N2 physisorption, pyridine FTIR, pH measurements, contact angle measurements, 27Al MAS NMR, and the crush test. Catalytic properties were investigated in the citronellal cyclization as a model reaction. The reaction was performed in the trickle-bed reactor at 70 °C, 10 bar of Ar with 0.086 M initial citronellal concentration in cyclohexane. The best results were obtained over attapulgite with isopulegols yield of 24% and stereoselectivity to the desired isopulegol isomer of 61%. Attapulgite had the highest meso-to-micropore volume ratio, the highest basicity, a low Brønsted-to-Lewis acid sites ratio, and the lowest amount of Brønsted acid sites compared to other extrudates. In addition, same clay exhibited the highest mechanical strength of extrudates.

Experimental study on combustion, performance, and emission behaviours of diesel /WCO biodiesel/Cyclohexane blends in DI-CI engine

Waste cooking oil biodiesel is considered a common way to generate clean energy in all countries. It can be used efficiently, like fossil fuel quality. To overcome the problem of poor combustion, an increase in the NOx and unburned hydrocarbon emissions, liquid, or solid additives were commonly used to improve combustion and emissions properties. In this study, the Cyclohexane (C6H12) as volatile organic and the flammable liquid compound has been applied as a micro additive for B60D40 fuel blends. Its effect on diesel engine combustion, performance, and emissions has been experimentally investigated. The C6H12 added into the diesel/biodiesel blends at different concentrations of 5, 10, and 15 % by volume basis. Two values of injection pressure have tested experimentally at different Cyclohexane concentrations. The experiment activity changed the fuel injection pressure of 150 and 250 bar, respectively, while the WCOB blends of B60D35c5, B60D30c10, and B60D25c15 have been used. The obtained results have been compared with the commercial diesel#1 and B60D40 fuel blends, respectively. The measured data show that the Cyclohexane additives dramatically improve engine emissions as well as engine performance. The CO, HC, and smoke density have decreased by increasing the Cyclohexane dose as a flammable additive. The NOx emission was reduced by increasing the C6H12 due to the fast combustion process and enhancing the premixed combustion period. Moreover, the increased injection pressure from 150 bars to 250 bars reduces the engine BSFC, HC, CO, NOx, smoke density, increasing engine BTE, CO2 emissions, and exhaust gas temperature.

Dual Emissive Gold(I)–Sulfido Cluster Framework Capable of Benzene–Cyclohexane Separation in the Solid State Accompanied by Luminescence Color Changes

A decanuclear gold(I)-sulfido complex, [(LH)4Au10S4]Cl2 (LH-Au10S4-Cl, where LH = 4,5-bis(diphenylphosphanyl)-2H-1,2,3-triazole), assembled from the reaction of H2S with the chlorogold(I) precursor obtained from the click reaction of [dppa(AuCl)2] (where dppa = 1,2-bis(diphenylphosphino)acetylene) with NaN3, is shown to display a bright dual green and red emission in the solid state. Single crystal X-ray diffraction (SCXRD) studies indicate a gold(I) cluster-based framework assembled through intermolecular halogen···hydrogen bonds as well as other weak interactions. The framework of LH-Au10S4-Cl is found to display high stability toward solvent molecules, with capability to encapsulate solvent molecules, such as benzene and cyclohexane, inside the crystal lattice voids via a single-crystal-to-single-crystal (SCSC) transformation. With different degrees of influence on the dual green and red emission, crystalline solids of LH-Au10S4-Cl exhibit remarkable solvatochromic luminescence in the presence of benzene and cyclohexane. Notably, due to the size confinement of the lattice cavities, the LH-Au10S4-Cl solids exhibit a high selectivity (>95%) toward benzene in a mixture of equimolar concentration of benzene and cyclohexane. This work has demonstrated the promising capability of gold(I)-sulfido cluster frameworks to serve as luminescent functional materials for the separation of benzene and cyclohexane.

Silicon nanowires/reduced graphene oxide nanocomposite based novel sensor platform for detection of cyclohexane and formaldehyde

The present work provides a new reduced graphene oxide (rGO) modified silicon nanowires (SiNW) nanocomposite-based platform for the fabrication of a sensor. The fabricated sensor was used for the detection of biomarkers of infectious diseases in an easy, inexpensive, and non-invasive way. SiNW have been synthesized using metal-assisted chemical etching technique (MACE) and were casted using GO at room temperature. Subsequently, SiNW/GO was reduced to SiNW/rGO nanocomposite under an inert atmosphere using argon gas and characterized using a scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), fourier transform infrared (FTIR), X-ray diffractometer (XRD) and Raman spectroscopy. This film was fabricated in the form of an electrode and utilized for the sensitive and selective detection of two volatile organic compounds (VOCs) namely cyclohexane and formaldehyde, found in the exhaled breath of patients with certain infections. The SiNW/rGO nanocomposite sensor showed a contrary response of 1.07 and 0.99 for 1 ppm concentration of cyclohexane and formaldehyde, respectively at room temperature. It showed a limit of detection (LOD) of 1 ppm and exhibits a fast response time of 30 s at ambient conditions. The recovery time of the sensor was 1–2 min and 3 min for cyclohexane and formaldehyde, respectively. Thus, the reported sensing approach using SiNW/rGO nanocomposite could exhibit a new nanocomposite for the fabrication of sensors having high sensitivity, selectivity, repeatability, and stability for target analytes.

Elimination of Cyclohexane by Using a Filter Cartridge a Photocatalytic Filtering Reactor

In this study, we present an effective solution for the treatment of toxic gases, based on a photocatalytic process as destructive process. The aim of this investigation is to study the efficiency of the photocatalytic Filtering reactor (PFR), for the treatment of cyclohexane which is chosen as target pollutant of anti-gas cartridges of type 'A'. Indeed, the influence the input concentration (a range of Cyclohexane concentrations defined in the values and exposure limits recommended by the different French, European or American standards), residence time in reactor, and type of catalyst were studied in detail. In addition, the conversion rate was controlled under a respiratory flow (standards: ISO / DIS 8996). Moreover, a TiO2 deposed on optical fiber was evaluated in these conditions. The obtained results confirm that this configuration of the reactor can present an extremely promising route for individual protection device as an autonomous cartridge for a gas mask.Keywords: Photocatalytic filtration reactor, air treatment, cyclohexane, TiO2 on optical fiber.

Prevention of Diabetic Complications by Walnut Leaf Extract via Changing Aldose Reductase Activity: An Experiment in Diabetic Rat Tissue.

Background Increased activity of aldose reductase (AR) is one of the mechanisms involved in the development of diabetic complications. Inhibiting AR can be a target to prevent diabetes complications. This study is aimed at evaluating the effect of cyclohexane (CH) and ethanol extracts (ET) of walnut leaves on AR activity in the lens and testis of diabetic rats. Methods Fifty-six male rats classified into seven groups as control and treatment groups and treated for 30 days. The treatment groups were treated with different concentrations of ET and CH. The diabetic control (DC) group was exposed to streptozotocin. AR activity was measured in the lens and testis. The expression of AR in the testis was evaluated by the immunohistochemistry method. Results Both extracts significantly reduced the AR activity (ng/mg of tissue protein) in the testis (0.034 ± 0.004, 0.038 ± 0.010, and 0.040 ± 0.007 in the treatment groups vs. 0.075 ± 0.007 in the DC group) and lens (1.66 ± 0.09, 2.70 ± 0.47, and 1.77 ± 0.20 in the treatment groups vs. 6.29 ± 0.48 in the DC group) of the treatment group compared to those of the DC group (P < 0.05). AR expression in the testes of the treatment groups was decreased compared with that of the DC group (P < 0.0001). Conclusion Walnut leaf extracts can reduce the activity and localization of AR in the testes and its activity in the lens of diabetic rats.

Comparison between the kinetics of cyclohexane absorption and desorption for heterogeneous bitumen nanofilms

We used a gravimetric technique to study the kinetics of cyclohexane absorption and desorption for bitumen films with thicknesses ranging from ~50 nm to ~1000 nm by monitoring their relative mass uptake and release rates at 25 ℃ and 1 atm, respectively. In the absorption experiments, bitumen films were saturated with cyclohexane by exposing them to a carrier gas containing cyclohexane vapor at two relative saturations (RS) – 20% and 90% separately. These films were then used in the following desorption experiments. The absorption rate was about two times faster than the desorption rate. Furthermore, the absorption rate exhibited a linear inverse film thickness dependence while desorption a non-linear one. The cyclohexane diffusivity in the films exhibited a linear positive film thickness dependence with it being higher in absorption than that in desorption. The observations implied that amounts of cyclohexane dissolved and evaporated controlled the overall absorption and desorption rates, respectively. The inverse film thickness dependence of such rates was due to the decreasing influence of the hydrophilic substrate on the concentration gradient of bitumen molecules with different degrees of polarity in the films. Mass uptake was observed in the early stage of the desorption experiments of the 20% RS samples, especially those with low bitumen coverages. This observation seemed to be a feature of nanoscale films. We speculated that cyclohexane evaporated into the carrier gas adjacent to the sample surface dissolved back into the bitumen film as a result of a cyclohexane concentration gradient reversal.

Determination of Cyclohexene in workplace air by Solvent desorption gas chromatography

Objective: To establish a solvent desorption gas chromatography method for determination of cyclohexene in workplace air. Methods: Cyclohexene in the air of workplace was collected with carbon tube and desorbed by carbon disulfide. The target toxicant was separated with the GC column and analyzed with FID detector, identified by retention time, and quantified by peak area. Results: The linear range of cyclohexene in the air of workplace was 0.77~4 050.00 μg/ml, with a correlation coefficient of 0.9999. The limit of detection was 0.23 μg/ml. The lower limit of quantification was 0.77 μg/ml. The minimum detectable concentration was 0.15 mg/m(3) under1.5 L sampling volume and 1.0 ml extraction solution volume. The within-run precision of different cyclohexene concentrations was 0.62%~1.9% and the between-run precisions was 1.5%~3.5%; The average extraction efficiency was 96.4%; Penetration capacity (100 mg of carbon tube) was 29.4 mg; The average collection efficiency was 100%; The samples could be stored for 7 days at room temperature. When placed in 4 ℃ refrigerator, the samples could be stored for 14 days. The potential coexistence of cyclohexane, hexane, benzene, toluene and ethylbenzene with cyclohexene in the air did not interfere with the results of determination. Conclusion: This method has high sensitivity, precision, accuracy and lower limit of detection and it is applicable for determination of cyclohexene in workplace air.

STUDY OF HETEROMOLECULAR INTERACTION OF NONAQUEOUS BINARY SOLUTIONS

In this work, the refractometry method was used to study of the molecular interactions and structural characteristics of dimethylformamide-ethanol and cyclohexane-ethanol binary mixtures. The refractive indices of mixtures were measured over a wide range of dimethylformamide and cyclohexane concentrations (0−1.0 mole fractions) at 25°С. It has been shown that heteromolecular complexes in binary solutions are formed at the concentration of ∼0.5 mole fraction of those compounds due to strong H-bonds. Relatively weak interactions are determined at a concentration of ∼0.2 and ∼0.9 mole fraction of dimethylformamide and ∼0.2 and ∼0.8 mole fraction of cyclohexane.

Mechanism of the dissolution of methane in the complex micellar system of NaOA/cyclohexane

The surfactant sodium oleate (NaOA) has important applications in dissolving methane, but there is insufficient research regarding the dissolution mechanism of methane in compound solutions of NaOA. Cyclohexane can also be used as a reagent to dissolve methane because of the similar phase dissolution principles. Thus, surfactant NaOA and the compounding reagent cyclohexane are selected as the experimental subjects of this study. In this study, the optimum ratio of NaOA to cyclohexane and the dissolution mechanism of methane in the mixed solution are microscopically determined by measuring the amount of methane dissolution, critical micelle concentration, particle size, and micelle morphology in the mixed solutions. Compared with the single NaOA solution, the mixed solutions of NaOA and cyclohexane have lower critical concentrations of micelles, more concentrated micelle particle size distributions, and more extended and aggregated micelle morphologies, all of which lead to higher methane solubilities in the mixed solutions. The optimum NaOA to cyclohexane ratio for dissolving methane is 1:3. The NaOA to cyclohexane concentration ratio of 1:3 demonstrates the lowest critical micelle concentration, which is most likely to generate micelles with a hydrophobic environment favorable for the dissolution of methane. The mixed solution at this ratio also demonstrates the most suitable particle size distribution and micelle morphology for the retention of methane in the core of the micelle.

Analysis and Classification of Liquid Samples Using Spatial Heterodyne Raman Spectroscopy

Spatial heterodyne spectroscopy (SHS) is used for quantitative analysis and classification of liquid samples. SHS is a version of a Michelson interferometer with no moving parts and with diffraction gratings in place of mirrors. The instrument converts frequency-resolved information into a spatially resolved one and records it in the form of interferograms. The back-extraction of spectral information is done by the fast Fourier transform. A SHS instrument is constructed with the resolving power 5000 and spectral range 522-593 nm. Two original technical solutions are used as compared to previous SHS instruments: the use of a high-frequency diode-pumped solid-state laser for excitation of Raman spectra and a microscope-based collection system. Raman spectra are excited at 532 nm at the repetition rate 80 kHz. Raman shifts between 330 cm-1 and 1600 cm-1 are measured. A new application of SHS is demonstrated: for the first time, it is used for quantitative Raman analysis to determine concentrations of cyclohexane in isopropanol and glycerol in water. Two calibration strategies are employed: univariate based on the construction of a calibration plot and multivariate based on partial least squares regression. The detection limits for both cyclohexane in isopropanol and glycerol in water are at a 0.5 mass% level. In addition to the Raman-SHS chemical analysis, classification of industrial oils (biodiesel, poly(1-decene), gasoline, heavy oil IFO380, polybutenes, and lubricant) is performed using the Raman-fluorescence spectra of the oils and principal component analysis. The oils are easily discriminated showing distinct non-overlapping patterns in the principal component space.