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The biological removal of hydrophobic volatile organic compounds (VOCs) is limited by their low water solu-bility and, therefore, low bioavailability. The addition of surfactants is a promising strategy, but to gain un-derstanding and broaden its applicability, its effect on the solubility of hydrophobic VOCs should be investigated. This study evaluates the effect of 2 synthetic surfactants (sodium dodecyl sulfate (SDS) and Tween 80) and 3 biological surfactants (surfactin, rhamnolipid and saponin) on the gas-to-liquid equilibrium partitioning coeffi-cient (KGL) of 7 hydrophobic VOCs at different critical micelle concentrations (CMC). For all VOCs, a decrease in their KGL was observed when a (bio)surfactant was added at 1 and 3 CMC. The highest decrease in KGL (71 - 96 %) was observed for all compounds when SDS was added at 3 CMC, whereas the smallest effect was noticed when Tween 80 or surfactin (5.1 - 75 %) were added at both concentrations. The results are explained in terms of the (bio)surfactant and VOC physical-chemical properties (e.g. CMC and polarity). This is the first study evaluating the effect of biological surfactants on KGL. These fundamental data are essential to improve the design and modeling of air treatment systems using (bio)surfactants.

Biji buah alpukat (Persea americana) merupakan sumber limbah biomassa yang dapat dimanfaatkan sebagai sumber energi alternatif. Pada bagian biji alpukat mengandung selulosa, hemiselulosa, lignin, lipid, protein. Tujuan dari penelitian ini adalah menganalisa pengaruh berat biji alpukat dan solvent n heksana terhadap persentase yield minyak biji alpukat dan mengetahui karakteristik persentase FFA, kadar air, impurities, bilangan iodine, bilangan peroksida dan bilangan saponifikasi minyak dari biji alpukat yang dihasilkan dari proses ekstraksi. Metode penelitian ini dilakukan dengan mengestraksi biji alpukat menggunakan soklet ekstraksi dan solvent n-heksana dengan temperatur 70 °C, tekanan 1 atm dan waktu 240, 360, 480 menit. Hasil penelitian menunjukan variabel berat biji alpukat, volume pelarut dan lamanya waktu ekstraksi mempengaruhi peningkatan jumlah minyak biji alpukat yang dihasilkan. Dari penelitian yang dilakukan yield tertinggi dihasilkan dari ekstraksi biji alpukat adalah sebesar 30,15 % pada variabel massa biji 60 gram, waktu ekstraksi 480 menit dan volume pelarut 300 ml. Hasil analisa kualitas minyak biji alpukat terhadap persentase FFA, kadar air, impurities, bilangan iodine, bilangan peroksida dan bilangan saponifikasi telah memenuhi standar SNI. Namun pada analisa impurities pada proses ekstraksi biji alpukat 60 gram dengan volume n-heksana 300 ml melebihi standar SNI. Hasil uji Gas Chromatography menunjukkan bahwa minyak biji alpukat mengandung senyawa asam lemak dan konsentrasi oleic acid adalah yang tertinggi dibandingkan unsur kimia yang lain. Avocado seeds (Persea americana) are biomass waste that can be used as an alternative source of energy. Avocado seeds contain cellulose, hemicellulose, lignin, lipids, and protein. This research studied the effects of avocado seed weight and n-hexane solvent on the percentage of avocado seed oil yield and determined the characteristics of the FFA percentage, water content, impurities, numbers of iodine, peroxide and oil saponification of obtained from the extraction process. Avocado seeds were extracted using an extraction sox and n-hexane solvent at 70 °C, 1 atm and time 240, 360, 480 minutes. The results showed that avocado seed weight, solvent volume and extraction time affected the amount of avocado seed oil yield. The highest yield was 30.15% obtained from seed mass of 60 grams with 480 minute extraction time and 300 ml solvent. The results also showed that the quality of avocado seed oil in relation to FFA percentage, moisture content, impurities, iodine number, peroxide number and saponification number have fulfilled the SNI standards. However, the analysis of impurities in the extraction process of 60 grams of avocado seeds with a volume 300 ml of n-hexanes exceeds the SNI standard. The Gas Chromatography test showed that vocado seed oil contained fatty acid compounds with highest concentration of oleic acid among other chemical elements.

A high number of infections from year to year require infectious diseases to get serious attention. The antimicrobial compound exploration must be continued to anticipate the development of infectious diseases. The purpose of this study was to find out in vitro antimicrobial activity of n-hexane, ethyl acetate, and ethanol fractions of Piper betle green leaves against S. aureus , and profiles of secondary metabolite compounds contained in these three extracts. The antimicrobial activity test was carried out by disk diffusion test of the fraction of n-hexane, ethyl acetate, and ethanol at a concentration of 6,25, 12,5, and 18,75 µg/disk. Detection of secondary metabolite content was done by the Thin Layer Chromatography method with stain-view reagents. The highest antimicrobial activity was found in the ethyl acetate fraction and was significantly different from the activity in the ethanol and n-hexane fractions. However, the antibacterial activity of all fractions was lower compared to the positive control of amoxiclav 30µg/disk. The phytochemical screening results of secondary metabolites of each fraction were shown that the n-hexane fraction contained alkaloids, terpenoids, flavonoids, polyphenols, and anthraquinone; the ethyl acetate fraction contained terpenoids, polyphenols, and anthraquinone; while the ethanol fraction contained alkaloids, terpenoids, polyphenols, and anthraquinone. Based on the test results, it is concluded that all fractions of Piper betle leaf extract had high antimicrobial activity; meanwhile, the ethyl acetate fraction had the highest activities among others. Each fraction was proven to have a different composition of secondary metabolites.

Oil from neem and yellow oleander seeds were extracted using Soxhlet extractor with normal hexane as solvent and characterized using standard methods and their Physico chemical properties determined. The results revealed that the oil yields of neem and yellow oleander seeds are 38.80% and 49.69% respectively. Both oil samples contain high free fatty acid values, 8.77% for neem and 7.21% for yellow oleander. The characterization revealed the following results for neem seed oil; saponification value = 185.50 mg KOH/g, acid value = 17.54 mg KOH/g, iodine value = 58 mg I/100g, peroxide value = 7.95 mg/peroxide/kg, viscosity at 40 °C = 37.80 mm/s2, specific gravity = 0.87, and refractive index = 1.469 while saponification value = 196.30 mg KOH/g, acid value = 14.42 mg KOH/g, iodine value = 81 mg I/100g, peroxide value = 4.20 mg/peroxide/kg, viscosity at 40 °C = 31.40 mm/s2, specific gravity = 0.96, and refractive index = 1.467 for yellow oleander seed oil. The results of the experimental analyses carried out in this study indicate that neem and yellow oleander seeds are high-yielding and good sources of oil for commercial biodiesel production. Values obtained for physico chemical properties of the extracted oils fall within the acceptable limits for oils suitable for biodiesel production by international standards. High free fatty values obtained revealed that the oils must undergo acid esterification before transesterification to avoid the formation of soap.

This work presents a modeling procedure for a tall photocatalytic fluidized bed photoreactor used for the photocatalytic oxidation of n-hexane on the anatase TiO2 surface. The modeling strategy split the reactor into two parts: a lower dense phase, with high solids concentration behaving as a bubbling bed treated as a continuous stirred tank reactor (CSTR); and an upper lean phase of low solids concentration behaving as a plug-flow reactor (PFR). The Langmuir-type kinetic parameters were obtained for the flow rate of 1.67 × 10-4 m3 s-1 and catalyst mass of 0.1 kg. The model revealed a good adjustment with experimental data when predicting conversion results for the same experimental conditions, but deviations grew as flow rates and catalyst loads departed from those values in which the model was obtained.

Highlights • Ultrasonic activity was investigated in polar and nonpolar organic solvents. • Ultrasonic/mechanical soil washing for PCBs removal was also investigated. • Ultrasonic washing had higher washing efficiency compared to conventional process. • Degradation of PCBs in the liquid phase was investigated in photolytic processes., Ultrasonic soil washing processes using organic solvents were investigated for the development of novel remediation technologies for persistent organic pollutants (POPs)- contaminated soils. Aluminum foil erosion was first tested to understand sonophysical activity in water, methanol (polar) and n-hexane (nonpolar) in a 28 kHz double-bath-type sonoreactor. Significant sonophysical damage on the aluminum foil was observed at the antinodes for all solvents, and the order of degree of sonophysical damage was as follows: water > methanol > n-hexane. Subsequently, conventional (mechanical mixing only) and ultrasonic soil washing (mechanical mixing and ultrasound) techniques were compared for the removal of polychlorinated biphenyls (PCBs) from soil. Two types of contaminated soils, fresh (Soil A, C0 = 2.5 mg/kg) and weathered (Soil B, C0 = 0.5 mg/kg), were used and the applied soil-to-liquid (S:L) ratio was 1:5 and 1:10 for methanol and n-hexane, respectively. The polar solvent significantly increased washing efficiencies compared to the nonpolar solvent, despite the nonpolar nature of the PCBs. Washing efficiency was significantly enhanced in ultrasonic soil washing compared to conventional washing, owing to macro- and micro-scale sonophysical actions. The highest washing efficiencies of 90% for Soil A and 70% for Soil B were observed in the ultrasonic washing processes using methanol. Additionally, a single operation of the ultrasonic washing process was superior to two sequential processes with conventional mixing in terms of washing efficiency, consumption of washing agents, treatment of washing leachate, and operation time. Finally, the removal of PCBs in an organic solvent (methanol) was investigated in photolytic and sonolytic processes for the post-treatment of soil washing leachate. A photolysis efficiency of 80% was obtained within 60 min of UV exposure for intensities of 1.0, 2.0, and 4.0 W/cm2. The primary mechanism of PCBs degradation is photolytic dechlorination. In contrast, no degradation was detected in the sonolytic process, as the excess organic solvent acted as a strong radical scavenger.

The extraction of fat/oil from fleshing by-products using moist heating (boiled and steamed) produces a fat that contains large amounts of impurities and which is bluish color, whereas when using fatty solvents, it is necessary to dry the ingredients. The purpose of this study was to determine the fat/oil characteristics from fleshing by-products extracted using a combination of wet rendering (temperatures of 80, 90 and 100 °C, and times 1, 2 and 3 hours) with n-hexane. The combined treatment of wet rendering (temperature 90 °C and duration 2 hours) with n-hexane gave rise to the production of fat with the highest yield (11.10% w/w). The higher the temperature and the longer the wet rendering process, results in fat with higher levels of free fatty acid and the saponification value, but the lower the number of peroxides and the darker the color. The fats/oils consist of 37 fatty acid compounds, composed of saturated and unsaturated fatty acids. There are six very present fatty acid compounds, namely butyric acid methyl ester, tetradecanoic acid methyl ester, cis-10-pentadecanoic acid methyl ester, palmitoleic acid methyl ester, octadecanoic acid methyl ester and trans-9-elaidic acid methyl ester.

Optimization of post polymerization processes of polyolefin elastomers (POE) involving solvents is of considerable industrial interest. To this aim, experimental determination and theoretical interpretation of the thermodynamics and mass transport properties of POE-solvent mixtures is relevant. Sorption behavior of n-hexane vapor in a commercial propylene-ethylene elastomer (V8880 VistamaxxTM from ExxonMobil, Machelen, Belgium) is addressed here, determining experimentally the sorption isotherms at temperatures ranging from 115 to 140 °C and pressure values of n-hexane vapor up to 1 atm. Sorption isotherms have been interpreted using a Non Random Lattice Fluid (NRLF) Equation of State model retrieving, from data fitting, the value of the binary interaction parameter for the n-hexane/V8880 system. Both the cases of temperature-independent and of temperature-dependent binary interaction parameter have been considered. Sorption kinetics was also investigated at different pressures and has been interpreted using a Fick’s model determining values of the mutual diffusivity as a function of temperature and of n-hexane/V8880 mixture composition. From these values, n-hexane intra-diffusion coefficient has been calculated interpreting its dependence on mixture concentration and temperature by a semi-empiric model based on free volume arguments.

This manuscript is focused on the relationship between sol-gel synthesis processes and the development of new active phases with fitted morphology, porosity and surface chemistry. The influence of the above parameters on the catalytic performance of the prepared materials for the aromatization of n-hexane to benzene is also evaluated. Different series of catalysts were prepared, either using noble metals (i.e., Pt) or metal oxides (i.e., Mo, W), as active phases. In both cases, the catalytic performance and stability of classical aromatization catalysts was significantly improved. Interesting one-pot carboreduction process of the metal oxide during carbonization is suggested as a real alternative for the preparation of high-performance aromatization catalysts, leading to the formation of less acidic and non-stoichiometric oxides and carbides., ERDF/Ministry of Science, Innovation and Universities-State Research Agency RTI 2018-099224-B100, Nano4Fresh project as part of PRIMA Programme - European Union PCI2020-112045

OBJECTIVE: To evaluate the saponins rich fraction of Dioscorea deltoidea (D. deltoidea) for possible antinociceptive activity. METHODS: Saponins were extracted from the crude methanolic extract of D. deltoidea (Wall). Presence of saponins was confirmed through phytochemical screenings. Acute toxicity test was performed to determine safe dose range of the saponins rich fraction (n-butanol fraction) using balb C Mice. The saponins rich fraction was assessed for possible antinociceptive activity using acetic acid induced writhing method and hot plate method. Data was analyzed using Graph Pad Prism 6. ANOVA was used to determine the significance of test samples versus positive control at 95% CI with p

Наведено результати досліджень вилучення олії з неподрібненого та подрібненого насіння соняшника різних фракцій методом екстрагування. Досліджено механізм екстрагування та кінетику процесу. Показано, що процес вилучення олії з насіння соняшника складний і складається із внутрішньо-дифузійного і зовнішньо-дифузійного перенесення олії. Вказано, що процес є аналогічним екстракційному вилученню цільових компонентів із насіння більшості видів рослинної сировини. Наведено методику експериментального визначення коефіцієнта дифузії як найповільнішої стадії процесу, яка визначає швидкість всього процесу екстрагування. Показано, що вилучення олії методом екстрагування можна здійснити ефективніше порівняно з методом пресування, особливо у тих випадках, коли вміст олії в насінні низький. The results of the research of extraction of oil from the none-crushed and crushed sunflower seeds of different fractions by the method of extraction are presented. The mechanism of extraction and process kinetics is investigated. It has been shown that the process of extracting oil from sunflower seeds is complex and consists of both intra-diffusion and external-diffusion transfer of oil. It is stated that the process is similar to the extraction of the target components from the seeds of most types of plant raw materials. The method of experimental determination of the diffusion coefficient as the slowest stage of the process, which determines the speed of the entire extraction process, is presented. It has been shown that the extraction of oil by the extraction method can be carried out more efficiently than the pressing method, especially in cases where the oil content of the seeds is low.

A series of CeαMn1-αO2 catalysts supported on g-alumina with various molar concentrations of Ce (α, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce0.33Mn0.67O2 obtained by method 2 presented the best activity, probably due to the enrichment of Ce4+, Mn3+ and Mn4+ surface species, an excess of superficial oxygen species and an easy reducibility as well as the lowest apparent activation energy. © 2020 Sociedade Brasileira de Quimica. All rights reserved.

The development of reliable and green methods for the fabrication of metallic nanoparticles (NPs) has many advantages in the field of nanotechnology. In this direction, the present work describes an eco-friendly and cost-effective protocol for the production of silver NPs (AgNPs) using an aqueous extract of Quercus semecarpifolia leaves. Different techniques were carried out for the characterisation of the synthesised AgNPs. The ultraviolet-visible spectroscopic analysis showed the highest absorbance peak at 430 nm. The particle size and structure were confirmed by scanning electron microscopy as well as transmission electron microscopy (TEM) analysis. From TEM imaging, it was revealed that the formed particles were spherical with an average size of 20-50 nm. The crystalline nature of the NPs was determined by X-ray powder diffraction patterns. Thermogravimetry and differential thermal analysis were also evaluated by a temperature increment from 100 to 1000°C. Bio-inspired synthesis of AgNPs was performed for their pharmacological evaluation in relation to the activities of the crude methanolic, n -hexane, chloroform, ethyl acetate, and aqueous extracts. Good cytotoxic activity was exhibited by the green-synthesised AgNPs (77%). Furthermore, the AgNPs were found to exhibit significant antioxidant activity at 300 μg/ml (82%). The AgNPs also exhibited good phytotoxic potential (75%).

The article discusses the problem of using canola oil and n-hexane mixtures in diesel engines with storage tank fuel injection systems (common rail). The tests results of the combustion process in the dynamic operating conditions of an engine powered by these mixtures are presented. On the basis of the conducted considerations, it was found that the addition of n-hexane to canola oil does not change its energy properties and significantly improves physicochemical properties such as the surface tension and viscosity. It contributes to the improvement of the flammable mixture preparation process and influences the course of the combustion process.

Some of the secondary metabolites present in red algae are terpenoids, quinones, flavonoids, alkaloids, essential oils, diarylheptanoids, steroids, cardioglycosides, oils and fats, tannins, carbohydrates. Activity of rhizomes, leaves and flowers red leaf is as antimicrobial, anti-fungal, anti-oxidants, anti-tumor, anti-cancer and vasodilator. One way to improve the physical, chemical and bioactivity properties of natural compounds was to make them into nanoparticles. In this study, the isolation of bioactive compounds contained in red laos rhizome by maceration method using ethanol solvent was done, then partitioned with n-hexane and ethyl acetate. The extracts thus obtained are fabricated into nanoparticles. Extracts in bulk and nanoparticles were then tested for cytotoxic activity using BSLT method. Results of analysis with PSA showed that ethanol extract had size 410,8 nm, n-hexane extract 220,7 nm and ethyl acetate extract 208,3 nm. The results of cytotoxic tests showed that nanoparticle size increased cytotoxic activity. Ethyl acetate extract was most active compared to ethanol and n-hexane extracts with LC50values of 17.919; 84,956; 166,526 ppm. Whereas the nanoparticle size was respectively 10,491; 74,072 and 84,197 ppm. Cytotoxic activity increases with nanoparticle fabrication.

Spent coffee grounds (SCGs) generated in coffee processing for beverages and other products are a very significant organic residue that needs to be properly treated. Waste valorization via oil extraction has the potential to obtain compounds that can be used for producing biodiesel or other high-value products, such as polymers. This work focuses on the ultrasound-assisted extraction of SCG oil using n-hexane as a solvent. Three key process parameters are analyzed: temperature, extraction time, and liquid/solid (L/S) rate of solvent, using a central composite rotatable design (CCRD), an analysis that, to the author’s knowledge, is not yet available in the literature. The data were analyzed using the software StatSoft STATISTICA 13.1 (TIBCO Software Inc., Palo Alto, CA, USA). Results show that all parameters have a statistical influence on the process performance (p < 0.05), being the L/S ratio the most significant, followed by extraction time and temperature. An analysis of variance (ANOVA) showed that the empirical model is a good fit to the experimental data at a 95% confidence level. For the range of conditions considered in this work, the optimal operating conditions for obtaining an oil extraction yield in the range of 12 to 13%wt are a solvent L/S ratio of around 16 mL g−1, for a temperature in the range of 50 to 60 °C, and the longest contact time, limited by the process economics and health and safety issues and also, by the n-hexane boiling temperature.

International audience; This study concerns the oxidation of n-hexane. It was conducted in continuous flow fused-silica jet-stirred reactor (JSR) at 10 atm and an equivalence ratio of 0.5. n-Hexane initial concentrations were (i) 2500 ppm with a mean residence time of 1.5 s and (ii) 1000 ppm with a mean residence time of 0.7 s; we operated in the cool-flame regime for temperatures ranging from 540 to 720K and 530 to 800K, respectively. Products were analyzed and quantified in the gas phase using gas chromatography (with flame ionization, thermal conductivity, and quadrupole mass spectrometry) and Fourier transform infrared spectrometry. Products of low-temperature oxidation were sampled in the JSR and trapped in acetonitrile for characterization using an Orbitrap Q-Exactive®. Flow injection analyses (FIA) and ultra-high pressure liquid chromatography (UHPLC) coupled with atmospheric pressure chemical ionization (APCI +/-modes)-high resolution mass spectrometry (HRMS) analyses were used to characterize hydroperoxides (C6H14O2), keto-hydroperoxides (C6H12O3, C3H6O3, C4H8O3, and C5H10O3), cyclic ethers (C6H12O), carboxylic acids (C2 to C6), ketones (C3 to C6), diones (C6H10O2), unsaturated ketones (C6H10O and C6H8O), unsaturated diones (C6H8O2), and highly oxygenated molecules (C6H12O4-8) produced by addition of three and four oxygen molecules on fuel's radicals. To confirm the presence of hydroxyl or hydroperoxyl groups in the oxidation products we used H/D exchange with D2O. 2,4-Dinitrophenylhydrazine (2,4-DNPH) derivatization was used to characterize and confirm the presence of different carbonyls which can be formed during the low temperature oxidation of n-hexane. An available kinetic reaction mechanism including 3 rd O2 addition on fuel's radicals was used to simulate the formation of the presently detected keto-hydroperoxides (KHP) and highly oxygenated molecules (HOMs).

A mixture of canola oil (Co), n-hexane (Hex), and ethyl alcohol (Et) was proposed as a new energy material for powering diesel engines. For this purpose, surface tension, density, and viscosity measurements, as well as engine tests, were performed for 88%Co10%Hex2%Et and 83%Co15%Hex2%Et mixtures at 20 °C. The adsorption and volumetric properties of these mixtures were compared to those of individual mixture components, as well as diesel fuel (Df) and oleic, linoleic, α-linolenic, palmitic, and stearic acids. It was revealed that the values of surface tension, viscosity, and density of Co were higher than those of the Co components. The addition of 10% Hex and 2% Et to Co caused a more than twofold decrease in its viscosity, while the addition of 15% Hex and 2% Et caused a more than fourfold reduction of Co viscosity. In addition, a mixture of Co with 2% Et and 10% Hex had a density similar to that of Df. In turn, theoretical calculations showed that the addition of n-hexane and ethanol to canola oil only slightly changed its heat of combustion. Engine tests were carried out at fixed engine rotational speeds, with a direct gearbox ratio (4th gear). The quick-changing parameters of the combustion process were registered using an AVL Indimicro system. In these tests it was found that the addition of Et to the mixture of Co and Hex did not significantly shorten the auto-ignition delay, but the kinetic phase during combustion disappeared, which had an impact on the combustion start angle.

The use of industrial waste streams as a source of biomass is beneficial, not only to reduce environmental problems, but also to save valuable resources. Waste streams containing volatile fatty acids (VFAs) are one such example. However, separation from these streams is challenging because of the low concentrations of VFAs found in aqueous solutions. In this study, medium-chain fatty acids (MCFAs) diluted in an organic solvent are used as extractants for VFAs from dilute aqueous solutions. MFCAs have the advantage of forming double hydrogen bonds, which makes them very interesting for the recovery of VFAs. Liquid-liquid extractions (LLE) are carried out using hexanoic, octanoic or decanoic acid as the MFCA extracting agents, diluted with either hexane or toluene for economy. The various VFAs extracted consist of either acetic, propionic or butyric acid. In this manner, the effect of parameters such as the alkyl chain length of the VFAs and MCFAs and the nature of diluent have been investigated. In addition, the influence of the concentration of MCFAs in the diluent (n-hexane and toluene) on the extraction efficiency of the various VFAs has been determined. Results suggest that the decrease in extraction efficiency by diluting an MCFA with a conventional solvent is not at all a linear function of volume fraction. Therefore, a diluted MFCA has the potential to be the more economic extractant rather than a pure MCFA, as very little extraction efficiency is sacrificed over relatively large ranges of dilution.

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol–gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N2 adsorption–desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n-hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n-hexane increased with the relative response and reached a plateau that stabilized at approximately −31 kJ mol−1 for Ph40 and Ph50 and at approximately −37 kJ mol−1 for Ph30. This indicates that the adsorbate–adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure. This work was supported by the Ministerio de Ciencia e Innovación (CTQ2009-07993). Paula Moriones is thankful to the Departamento de Industria y Tecnología, Comercio y Trabajo of the Navarre Government for fellowships (Ref. number 269/01/08).

Oleic, linoleic, and linolenic acids are the main components of canola oil and their physiochemical properties decide on the use of canola oil as fuel for diesel engines. Therefore, the measurements of the surface tension of oleic, linoleic, and linolenic acids being the components of the canola oil, as well as their contact angles on the polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), and engine valve, were made. Additionally, the surface tension and contact angle on PTFE, PMMA, and the engine valve of the oleic acid and n-hexane mixtures were measured. On the basis of the obtained results, the components and parameters of oleic, linoleic, and linolenic acids&rsquo, surface tension were determined and compared to those of the canola oil. Next, applying the components and parameters of these acids, their adhesion work to PTFE, PMMA, and the engine valve was calculated by means of various methods.

Background: Leptadenia hastata is a leafy, climbing plant of whose root, leaf and bark is widely consumed in Northern Nigeria. Decoctions made from the leaf is locally used in treatment of diabetes as well as for numerous trado-medicinal processes. This study investigates the physico-chemical as well as phytochemical compounds present in the n-hexane extract of Leptadenia hastata. Method: Physical and chemical profile was determined using Smart Spectro test kits and a mass spectrometer to determine the presence of elements and physical properties. Results: Phytochemical analysis revealed the presence of steroids, triterpenoids and cardiac glycosides. The elemental analysis revealed that Na, SO4 and PO4 had the highest levels in the extract. Pb, Hg and Cd were not detected which showed that the plant extract was not toxic. Other elements (NO4, Mn, Fe, K, Ni, Si, Cn, Zn, Ca, Mg, NH4, Cr and F) were present in varying concentrations which may contribute to its nutritive composition. Conclusions: Various elements present in Leptadenia hastata may have either a direct or indirect role in the control and management of diabetes mellitus, since diabetes is associated with marked alterations in trace elements concentrations and may replace diminished element stores in the treatment of diabetes mellitus.

International audience; Measurements of the thermal conductivity of supercritical n-hexane performed in a coaxial cylinder cell operating in steady state conditions are reported. The present 1321 data of the thermal conductivity of n-hexane were carried out along ten quasi-isotherms above the critical temperature. These data cover the temperature range from 508.17 K to 553.00 K and the pressure range 0.l to 10 MPa. An analysis of the various sources of error leads to an estimated uncertainty that do not exceed 4% (95 level of confidence). The parameters of a background equation previously determined from 577 data of the thermal conductivity of gas and liquid n-hexane are reused here in order to analyze the critical enhancement of the thermal conductivity as a function of temperature and density. A set of theoretical Ising-like equations are re-formulated to describe the thermal conductivity critical enhancement along the near-critical isochoric lines in terms of the effective power laws fitting the singular behavior of the needed fluid properties as functions of the finite temperature distance to the critical point. Assuming the knowledge of the regular temperature behavior of the viscosity, the critical enhancement of the thermal conductivity appears then only characterized by a single effective amplitude. Such a separated analysis of the well-defined temperature effects provides the empirical functional form of the density effects, as a 6th-order polynomial density function, which can be normed whatever the temperature. Finally, our complete formulation of the total thermal conductivity describes, within three standard deviations (with SD = 1.0388%), the 1898 thermal conductivity measurements of n-hexane from 293 to 612 K and densities up to 670 kg m−3.

WOS: 000506827300006, PubMed: 31997994, Introduction: Traditionally, Anthemis genus has been used for the treatment of gastrointestinal disorders, haemorrhoid and stomach ache in Europe. There are several in-vitro and in-vivo studies that showed the pharmacological properties of Anthemis species such as antibacterial, anti-inflammatory, antiedemic and hepatoprotective properties. Aim: Our study referred to the model of inflammation formed in rats; we aimed to evaluate anti-inflammatory properties of A. tricolor extracts. Material and methods: Five different extracts of A. tricolor were tested against the negative control and 2 different topical corticosteroids (betamethasone and hydrocortisone); n-hexane and sesquiterpene extracts of A. tricolor Bois showed significantly reduced erythema compared to the negative control. Results: Only n-hexane and sesquiterpene extracts of A. tricolor have the anti-inflammatory effect. Conclusions: This is the first report on anti-inflammatory activity of A. tricolor and we showed an anti-inflammatory effect of n-hexane and sesquiterpene extract of A. tricolor with UV erythema test as a_result, hence A. tricolor extracts can be used for the treatment of inflammatory skin diseases due to anti-inflammatory activity.

In this study, high silica ZSM-5 was selected as an adsorbent for the removal of toluene (TOL) and n-hexane (HEX) binary mixtures from aqueous solution over a wide range of concentrations. In comparison with the single component systems, the binary mixture induced to a selective adsorption by the ZSM-5 zeolite. As a matter of fact, a selective adsorption, described by a competitive dual site Langmuir adsorption isotherm, is revealed where alkane compound is preferred to the aromatic one. Results from adsorption isotherm were related to the structural answer of the ZSM-5 framework as a function of a HEX-TOL equimolar binary mixture adsorption. Rietveld refinements provided information about the relative position of both molecules within the ZSM-5, and on the intermolecular distances between the adsorption sites of HEX and TOL. Residuals of electron density calculated by mean of delta Fourier maps indicated the presence of both guest molecules but with a clear indication of preferential towards n-hexane, and a clear differential adsorption site distribution. The occurrence of host-guest interactions in the narrow intracrystalline micropores between the solid catalyst and embedded molecules have been revealed.

Effective thermal conductivity of the porous glasses saturated with the carbon dioxide, n – hexane, and oil has been researcher in the temperature intervals from 290 K to 380 K and at the pressures from 1.333Pa to 18.7 MPa. Heat passage mechanisms has been detected, the influence of temperature and pressure has been studies, the effect of CO2, C6H14, and oil molecules, being inside pores, on the behaviour of effective thermal conductivity of porous glasses. Heat passage mechanisms in the porous media saturated by fluid has been detected.

Studies of pulmonary toxicity induced by oral exposure to n-hexane are very few, in contrast to those studying the exposure by inhalation. This research tackles the oral toxic effect of n-hexane solvent on the lungs after subchronic exposure of Wistar male rats at 300, 600, and 1200 mg/kg, respectively, each day for 8 weeks. The pneumotoxicity observed in this study was marked by an immune toxicity in the form of a significant increase in the levels of white blood cells, lymphocytes, granulocytes, and eosinophils, as well as a significant increase in relative and absolute lung weight in both groups treated at the doses of 600 and 1200 mg/kg. n-Hexane also resulted in a significant increase in serum total proteins and acid phosphatase in the 3 doses tested daily for 8 weeks. In addition, we found a significant increase in total protein and a decrease in glutathione at 600 and 1200 mg/kg, in the pulmonary homogenate. Furthermore, the rate of lipid peroxidation increased in the 3 doses tested. Histological findings revealed a pneumonia characterized by bronchopneumonia, fibronecrotic lesions, congestion, hemorrhage, type II pneumocyte hyperplasia, alveolar lesions, bronchial epithelium degradation, and inflammation.

Isomerisation of n-hexane was studied in the presence of acid and bifunctional metal-acid catalysts based on Keggin-type heteropoly acids (HPA), in particular focusing on Cs2.5H0.5PW12O40 (CsPW) and Pt/CsPW as the catalysts, using a fixed-bed microreactor under differential conditions (n-hexane conversion ≤ 10%) at 180–220 °C, ambient pressure and a ratio of n-hexane and H2 partial pressures of 0.06–0.24. The turnover rate of HPA-catalysed isomerisation was found to correlate with the acid strength of HPA (initial enthalpy of ammonia adsorption). Bifunctional Pt-HPA catalysts were more efficient than monofunctional HPA catalysts. In the isomerisation over Pt/CsPW bifunctional catalyst, n-hexane dehydrogenation step was found to equilibrate at a molar ratio of Pt and H+ surface sites Pts/H+ ≥ 0.8, corresponding to a Pt loading ≥6%. Bimetallic PtAu/CsPW catalyst showed higher activity in n-hexane isomerisation than Pt/CsPW, although the Au alone without Pt was inert. In the presence of Au, the turnover rate at Pt sites increased more than twofold. The effect of Au is attributed to PtAu alloying. Scanning transmission electron microscopy–energy dispersive X-ray spectroscopy (STEM-EDX) and X-ray diffraction (XRD) analyses of PtAu/CsPW indicated the presence of bimetallic PtAu nanoparticles with a wide range of Pt/Au atomic ratios.

Recently FT-IR spectroscopy has enjoyed renewed interest for detection and quantification of contamination by oils and grease (OG), especially in water samples. This is due to the development of a new approach using less harmful solvents. This paper presents the development of a new FT-IR method that uses n-hexane as a substitute to Freon 113 in the extraction process. This solvent has a high solubility for the desired organic compounds, low miscibility with water and a low boiling point to facilitate its removal from the extracted material. Results regarding the calibration curves, recovery, precision, detection and quantitation limits are presented. Even if the recovery is not too high (45%), the preconcentration factor of 2 × 103 permits the detection of OG at levels >83 μg/L.

Densities data of n-hexane, toluene and dichloromethane at temperatures 288.15-413.15 K and at pressures 0.1-60 MPa, determined in our previous work, were fitted to the modified Tait equation of state. The fitted temperature-pressure dependent density data were used to calculate the derived properties: the isothermal compressibility, the isobaric thermal expansivity, the difference between specific heat capacity at constant pressure and at constant volume and the internal pressure, over the entire temperature and pressure intervals specified above. In order to assess the proposed modeling procedure, a comparison of the obtained values for the isothermal compressibility and the isobaric thermal expansivity with the corresponding literature data were performed. The average absolute percentage deviations for isothermal compressibility were: for n-hexane 2.01-3.64%, for toluene 0.64-2.48% and for dichloromethane 1.81-3.20%; for the isobaric thermal expansivity: for n-hexane 1.31-4.17%, for toluene 0.71-2.45% and for dichloromethane 1.16-1.61%. By comparing the obtained deviations values with those found in the literature it can be concluded that the presented results agree good with the literature data. [Projekat Ministarstva nauke Republike Srbije, br. 172063]

In this work an apparatus for density measurements in the compressed liquid regions was presented. This installation is based on the use of the DMA HP density measuring cell and the DMA 5000 densimeter (both instruments are products of Anton Paar, Gratz, Austria). Calibration of DMA HP cell was performed by applying the classical method where a vacuum, water and n-decane were recommended to be used as calibration fluids. To test the capabilities of the set-up, the densities of n-hexane, toluene and dichloromethane were measured in the temperature interval 288.15 to 413.15 K and the pressure range 0.1-60 MPa. The obtained results were compared with the corresponding values found in the literature. Depending on the literature selected for comparison (the temperature and pressure ranges available) the average absolute percentage deviations were: for n-hexane 0.03-0.10%; for toluene 0.04-0.08% and for dichloromethane 0.02-0.03%. A deeper insight into the results of this work shows that most of them are in a good agreement with the literature values; higher discrepancies are remarked in the vicinity of the ends of the temperature and pressure ranges. [Projekat Ministarstva nauke Republike Srbije, br. 172063]