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1

Ecological aspects of using mixtures of canola oil with n-hexane in diesel engine

Longwic Rafał, Sander Przemysław, Tatarynow Dawid

Combustion Engines

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2022

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R. 61, nr 3

56--60

EN

The article discusses the results of research on the use of canola oil and canola oil with the addition of n-hexane in a compression-ignition engine. An engine with a Common Rail injection system was tested in real traffic conditions on the road and on a chassis dynamometer. The tested fuels were fed to the engine by an additional fuel supply system. An analysis of the effect of the addition of n-hexane on the emission of the main components of toxic exhaust gases was carried out. The proposed solution may contribute to extending the service life of currently used compression ignition engines due to the improvement of the ecological properties of this type of drive sources.

2

Adsorption of n-hexane on a low-cost adsorbent obtained from waste tyres and its microwave regeneration

Kotkowski Tomasz, Cherbański Robert, Molga Eugeniusz

Chemical and Process Engineering

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2022

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Vol. 43, nr 1

57–-80

EN

This work investigates adsorption of n-hexane on activated tyre pyrolysis char (ATPC) and granular activated carbon (GAC) as a reference material in a fixed-bed column. Microwave-assisted regeneration is also considered. The adsorbed amount of n-hexane on ATPC is in the range of 37–58 mg/g. Microwave-assisted desorption of ATPC samples enables the recovery of up to 95% of adsorbed n-hexane in this non-optimized microwave setup with the efficiency of microwave energy conversion into heat of only 5–6%. For the 50% breakthrough time, ATPC and GAC are able to purify the n-hexane gas volumes in the ranges of 20–90 and 935–1240 cm3/g, respectively. While adsorption kinetics is not satisfactorily described by pseudo-first and pseudo-second order kinetic models, it is very well reflected by a family of dynamic adsorption models, which are modelled with a single logistic function. Internal diffusion is likely the rate limiting step during adsorption on ATPC, while external and internal diffusion likely plays a role in adsorption to GAC. Although microwave-assisted regeneration is performed in a general purpose microwave reactor, both adsorbents show excellent performance and are very good candidates for the adsorption process. Preliminary results show that magnetite can further reduce microwave energy consumption.

3

Tyre-derived activated carbon – textural propertiesand modelling of adsorption equilibrium of n-hexane

Kotkowski Tomasz, Cherbański Robert, Molga Eugeniusz

Chemical and Process Engineering

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2020

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Vol. 41, nr 1

25–-44

EN

There is general agreement that primary pyrolysis products of end-of-life tyres should be valorised toimprove the economics of pyrolysis. In this work, tyre pyrolysis char (TPC) is produced in a pyrolysispilot plant designed and built at our home university. The produced TPC was upgraded to tyre-derivedactivated carbon (TDAC) by activation with CO2, and then characterised using stereological analysis(SA) and nitrogen adsorption at 77 K. SA showed that the grains of TPC and TDAC were quasi-spherical and slightly elongated with a 25% increase in the mean particle cross-section surface area forTDAC. The textural properties of TDAC demonstrated the BET and micropore surface areas of 259 and70 m2/g, respectively. Micropore volume and micropore surface area were 5.8 and 6.7 times higher forTDAC than TPC at2nm, respectively. Then-hexane adsorption was investigated using experimentsand modelling. Eight adsorption isotherms along with three error functions were tested to model theadsorption equilibrium. The optimum sets of isotherm parameters were chosen by comparing sum ofthe normalized errors. The analysis indicated that the Freundlich isotherm gave the best agreementwith the equilibrium experiments. In relation to different activated carbons, the adsorption capacityof TDAC forn-hexane is about 16.2 times higher than that of the worst reference material and 4.3times lower than that of the best reference material. In addition, stereological analysis showed thatactivation with CO2did not change the grain’s shape factors. However, a 25% increase in the meanparticle cross-section surface area for TDAC was observed.

4

Numerical study on in-cylinder blending by means of a simultaneous direct injection of two liquid fuels in a heavy duty compression ignition engine

Kapusta Ł. J., Teodorczyk A.

Transactions of the Institute of Fluid-Flow Machinery

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2015

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nr 128

5--18

EN

Dual fuel combustion has been recently of high interest, mainly in terms of utilization of fuels different than diesel fuel in compression ignition engines. Depending on the properties of a fuel which is additional to diesel fuel, and the type of the additional fuel supply method the combustion process may be strongly modified comparing to single fuel combustion. Nowadays the modification of the combustion process becomes the reason for implementing the dual fuelling process. However, still the main reason for its implementation remains the utilization of nonconventional fuels in compression ignition engines. Among different types of dual fuel systems the one based on simultaneous direct injection of two fuels seems to be most flexible one. It allows to stratify the charge in the cylinder, blend two different fuels at any ratio and does not decrease volumetric efficiency. Therefore, this study aims at mixture formation in a heavy duty engine employing simultaneous direct injection of two different liquid fuels. Special attention was paid to spray breakup and simultaneous evaporation of two fuels which are the key processes in mixture formation.

5

Zastosowanie inwersyjnej chromatografii gazowej do charakterystyki właściwości adsorpcyjnych uporządkowanych węgli mezoporowatych

Jedynak K., Zdenkowski J., Święcicka A., Choma J.

Ochrona Środowiska

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2015

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Vol. 37, nr 2

3--10

PL

Badano właściwości adsorpcyjne uporządkowanych mezoporowatych węgli za pomocą inwersyjnej chromatografii gazowej (IGC). Wykorzystano cztery adsorbenty otrzymane metodą miękkiego odwzorowania w obecności kwasu solnego lub octowego, przy czym dwa z nich zawierały cząstki złota lub srebra. Przedstawiono charakterystykę struktury porowatej tych węgli na podstawie doświadczalnych izoterm adsorpcji azotu wyznaczając standardowe parametry oraz funkcje rozkładu objętości porów metodą opartą na teorii funkcjonału gęstości (DFT). Dodatkowo metodą IGC wyznaczono izotermy adsorpcji n-heksanu, benzenu oraz trichloroetenu. Stwierdzono, że na większości badanych węgli najlepiej adsorbował się n-heksan, kolejno benzen, a najsłabiej trichloroeten. Związki te były najlepiej adsorbowane przez mezoporowate węgle zawierające cząstki złota i srebra. Można sądzić, że było to wynikiem najsilniejszego oddziaływania cząsteczek adsorbatów z powierzchnią tych węgli. Świadczy o tym położenie maksimów funkcji rozkładu potencjału adsorpcyjnego otrzymane w badaniach adsorpcji n-heksanu, benzenu i trichloroetenu.

EN

Adsorption properties of ordered mesoporous carbons were studied using inverse gas chromatography (IGC). Four different adsorbents obtained by soft templating with hydrochloric or acetic acid were used, two of them containing particles of silver or gold. Porous structure characteristics of the studied carbons was presented on the basis of experimental isotherms of nitrogen adsorption. Standard parameters and functions of pore volume distribution were determined by Density Functional Theory method (DFT). Additionally, adsorption isotherms of n-hexane, benzene and trichloroethene were determined by IGC method. The highest adsorption for most of the examined carbons was observed for n-hexane, then benzene, while the lowest adsorption was determined for trichloroethene. The mesoporous carbons with silver and gold particles showed the highest adsorption of the tested compounds. This could be related to the strongest interactions between the adsorbate molecules and the carbon surface, determined on the basis of location of maximums of adsorption potential distribution functions for n-hexane, benzene and trichloroethene.

6

LES numerical study on n-hexane injection in a compression ignition engine

Kercheva B., Kapusta Ł. J., Teodorczyk A.

Archivum Combustionis

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2014

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Vol. 34 nr 2

155--167

EN

The aim of the study was the comparison of different approaches to modeling the injection process in a heavy duty compression ignition engine. The conducted numerical investigation concerned n-hexane direct injection into the engine combustion chamber. Simulations were performed using AVL Fire software, a CFD (Computational Fluid Dynamics) code based on the control volume method. In order to achieve engine conditions, computational model was built basing on piston and cylinder geometry of a real engine and the mesh deformation was defined according to crank mechanism dimensions of the engine. In presented simulations for modeling dispersed phase the Lagrangian approach was used. For capturing the turbulent patterns present in the flow, the Large Eddy Simulation (LES) approach was used. Three different nozzle outflow conditions were compared. In the simplest case, constant flow rate was defined. In the second one, linear stage of increase and decrease of flow rate was defined, and in the third one – the most advanced – data collected during previously done in-injector cavitating flow simulations were used to define the flow parameters on the nozzle outlet. Calculated results for all cases were analyzed and compared. The focus was on the initial stage of the spray. The results show that the way of defining parameters at the outlet influences not only the initial stage of the spray but the whole process.

7

Ultrasonic study of molecular interaction in binary liquid mixtures of n-hexane with alcohols

Santhi N., Sabarathinam P., Alamelumangai G., Madhumitha J., Emayavaramban M.

International Letters of Chemistry, Physics and Astronomy

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2012

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Vol. 5

59-71

EN

Ultrasonic velocity, viscosity and density of alcohol[s] in n-hexane have been measured AT various temperatures in the range of 303.15 - 318.15K. From the experimental data, the acoustical parameters such as molar volume, adiabatic compressibility, intermolecular free length and their excess values have been computed and presented as functions of compositions. The deviations from ideality of the acoustical parameters are explained on the basis of molecular interactions between the components of the mixtures. The variations of these parameters with composition of the mixture suggest the strength of interactions in these mixtures.

8

Benzen, cykloheksan, etylobenzen, n-heksan, metylocykloheksan, toluen – metoda oznaczania

Domański W.

Podstawy i Metody Oceny Środowiska Pracy

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2011

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Nr 1 (67)

35--44

XX

Metoda polega na adsorpcji na węglu aktywnym zawartych w powietrzu par: benzenu, cykloheksanu, etylobenzenu, n-heksanu, metylocykloheksanu i toluenu, a następnie desorpcji disiarczkiem węgla oraz analizie chromatograficznej roztworu uzyskanego w wyniku desorpcji.Metodę stosuje się do oznaczania wymienionych węglowodorów w powietrzu na stanowiskach pracy podczas przeprowadzania kontroli warunków sanitarnych. Oznaczalność metody wynosi: 0,15 mg benzenu, 7,5 mg cykloheksanu, 5 mg etylobenzenu, 3,75 mg n-heksanu, 25 mg metylocykloheksanu i 5 mg toluen w 1 m3 powietrza.

EN

This method is based on the adsorption of benzene cyclohexane, ethylbenzene, n-hexane, methy-locyclohexane and toluene vapors on active charcoal, desorption with carbon disulphide and determination with gas chromatography with an FID detector. The determination limit of this method in the air sample is 0.15 mg/m3 for benzene, 7.5 mg/m3 for cyclohexane, 5 mg/m3 for ethylbenzene, 3.75 mg/m3 for n-hexane, 25 mg/m3 for methylcyclohexane and 5 mg/m3 for toluene.

9

VLE in (C6H14 + C16H34) Mixture. Prediction with Elbro Free Volume Method

Wilczura-Wachnik H., Pawłowski T.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 1

107-116

EN

The main purpose of thisworkwas a search for the dependence of VLE prediction quality on the kind of chosen n-alkanemodel system. The activities and total vapour pressure for (n-C6H14 + n-C16H34) mixture at 293.15 K, 313.15 K and 333.15 K were successfully predicted with Elbro free volume method using three sets of UNIQUAC Aij interaction parameters: (1) Aij obtained with the semi-empirical quantum mechanical method AM1 (Austin Model 1) for (n-C6H14 + n-C16H34) system, (2) Aij adjusted to (n-C6H14 + n-C16H34) VLE experimental data, (3) Aij obtained with the CFF (Consistent Force Field) method for the chosen (n-alkane + n-alkane) model system. The predicted curves were compared with experimental data. It has been found that when sizes of the solvent molecule and a chosen segment in the second long chain molecule are comparable to the model system size then the UNIQUAC interaction parameters obtained with molecular mechanics quantitatively describe the real intermolecular forces in n-hexane + n-hexadecane system.

10

Heksan. Dokumentacja dopuszczalnych wielkości narażenia zawodowego

Jakubowski M.

Podstawy i Metody Oceny Środowiska Pracy

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2006

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Nr 1 (47)

109--129

PL

Heksan (n-heksan) jest bezbarwną, łatwopalną lotną cieczą stosowaną jako rozpuszczalnik organiczny klejów, lakierów, farb zwykłych oraz drukarskich, a także rozcieńczalnik i środek czyszczący. Związek jest używany w przemyśle gumowym, obuwniczym, spożywczym (do ekstrakcji olejów roślinnych z nasion), farmaceutycznym, kosmetycznym oraz chemicznym. W Polsce narażenie na heksan występuje głównie w przemyśle obuwniczym i w zakładach kaletniczych. Obecnie są wprowadzane takie zamienniki heksanu, jak metyloheksan i dimetyloheksan. Zgodnie z danymi Instytutu Medycyny Pracy z 2001 r. w Polsce na działanie heksanu o większym stężeniu niż wartość NDS wynosząca 100 mg/m3 było narażonych w środowisku pracy 136 osób. W dostępnym piśmiennictwie nie ma danych na temat padnięć zwierząt w wyniku narażenia na czysty heksan. Wartość LC50 dla mieszaniny heksanu i jego izomerów wyniosła 259 353 mg/m3 dla szczurów narażanych w ciągu 4 h. Stężenie to było znacznie większe niż stężenie wybuchowe (około 38 000 mg/m3). Wartość DL50 po podaniu szczurom do żołądka wyniosła 15 840 mg/kg. W przypadku przewlekłego narażenia ludzi na heksan narządem krytycznym jest obwodowy układ nerwowy. Efektem krytycznym jest zespół objawów klinicznych, zmian elektrofizjologicznych oraz morfologicznych w nerwach i mięśniach określany mianem polineuropatii obwodowej. U ludzi narażonych zawodowo na mieszaninę lotnych związków organicznych obecnych w rozpuszczalnikach do klejów i farb skutek ten stwierdzono wielokrotnie. Wyniki badań ludzi narażonych zawodowo na heksan, wprawdzie spójne jakościowo, nie pozwalają jednak na ustalenie zależności dawka-efekt, ze względu na niepełne dane w ocenie narażenia i występowanie narażenia złożonego. Wieloletnie narażenie na heksan o średnim stężeniu (240 mg/m3) nie powodowało tego skutku działania (NOAEL). Objawy ze strony obwodowego układu nerwowego stwierdzano najwcześniej w wyniku narażenia ciągłego, przekraczającego 18 h dziennie. U szczurów zwyrodnienie aksonów nerwów obwodowych wystąpiło w wyniku narażenia na heksan o stężeniu 1760 mg/m3 (9 tygodni, 7 dni/tydzień, 22 h dziennie). Gdy okres narażenia w ciągu dnia nie przekraczał 12 h, jego skutki były słabiej nasilone. Nie stwierdzano efektów działania toksycznego heksanu na inne układy i narządy. Wchłanianie heksanu może zachodzić w drogach oddechowych, przez skórę i w przewodzie pokarmowym. Retencja par heksanu w drogach oddechowych człowieka wynosi 28 - 34%. Około 10 - 20% wchłoniętej dawki heksanu ulega przemianom metabolicznym. Heksan ulega utlenieniu z udziałem cytochromu P-450, tworząc 1-heksanol, 2-heksanol i 3-heksanol. W wyniku utlenienia 2-heksanonu i hydroksylacji powstałego związku tworzy się 5-hydroksy-2-heksanon, który ulega dalszemu utlenieniu do 2,5-heksanodionu. Przyjęcie stężenia 204 mg/m3 heksanu za wartość LOAEL i jednego współczynnika niepewności uwzględniającego wrażliwość osobniczą daje wartość 100 mg/m3, co pozwala na zaakceptowanie wartości NDS równej 72 mg/m3 przyjętej przez Komitet Naukowy ds. Dopuszczalnych Stężeń w Środowisku Pracy Unii Europejskiej. Nie ma podstaw do zaproponowania wartości najwyższego dopuszczalnego stężenia chwilowego (NDSCh) i dopuszczalnego stężenia w materiale biologicznym (DSB) heksanu.

EN

n-Hexane is a colorless liquid, readily volatile with a boiling point of 69 oC. Technical grade hexane is a mixture of n-hexane and isomers of methylpentane and heptane. n-Hexane is commonly used as a solvent component of paints and thinners and especially glues. Ii is also present in gasoline. Occupational exposure to n-hexane may occur in rubber, chemical, pharmaceutical and shoe industries. n-Hexane is readily absorbed by all routes of exposure. In industrial settings, absorption takes place primarily via respiration. Retention rate of 28 – 34% has been reported. The rate of absorption of liquid hexane through the skin is 0.31 mg/cm2/h. Metabolism of n-hexane is important from the point of view of toxic effects. The metabolite, 2,5-hexanodion (2,5-HD), is responsible for toxic effects on peripheral nervous system inducing polyneuropathy. 2,5-HD can be derived in vivo from n-hexane via 2-hexanol, to either 2,5-hexanediol or methyl butyl ketone, and then to 5-hydroxy-2-hexanone, the last being interconvertible with 2,5-HD. n-Hexane is eliminated unchanged in exhaled air. After termination of exposure concentration in exhaled air it declines rapidly after cessation of exposure with apparent half-lives of 5 to 10 minutes and 100 minutes. Urinary excretion is negligible. The major elimination pathway is metabolism. The major metabolite is 2,5-hexanodione, which is eliminated with an apparent half-life of 13 – 14 hours and therefore, has a potential for accumulation over the workweek. Occupational exposure shows that n-hexane is toxic to the peripheral nervous system. Cases of sensorimotor to amyotrophic polyneuropathy have been observed among workers exposed to n-hexane in concentrations of up to 9000 mg/m3 for 48 hours or longer per week. Some of the affected individuals had exposure below 1800 mg/m3. In spite of numerous investigations in the industrial setting the dose-effect and dose-response relationships have not been established because workers were usually exposed to a mixture of solvents. The toxicity of n-hexane to induce polyneuropathy after repeated exposures was further confirmed by animal experiments. In rats, degeneration of axons in peripheral nerves occurred as a result of exposure to n-hexane in concentration of 1760 mg/m3 (9 weeks, 7 days/week, 22 h/day). The proposed occupational exposure limit (OEL-TWA) of 100 mg/m3 is based on the NOAEL (204 mg/m3) value derived from long-term (6.5 years) observation of the group of 14 persons exposed to a mixture of n-hexane and acetone and the uncertainty factor of 2.

11

Interactions of Some Organic Solvents: Hydrocarbons and Chloroalkene

Skowroń J., Miranowicz-Dzierżawska K., Zapór L., Gołofit-Szymczak M., Starek A.

International Journal of Occupational Safety and Ergonomics

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2001

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Vol. 7, No. 1

35--47

EN

Metabolic and toxicodynamic interactions of some organic solvents in rats repeatedly treated with medium dose levels were examined. It was shown that both n-hexane and ethylbenzene significantly inhibited tetrachloroethylene metabolism during a 2-week period. n-Hexane and tetrachloroethylene enhanced metabolism of ethylbenzene whereas ethylbenzene suppressed n-hexane metabolism only at the end of the experiment. Biochemical changes, especially the drop in the level of non-protein sulfhydryl groups in tissues of rats treated with organic solvent mixtures, were significantly less pronounced than those observed after these chemicals were administered separately. These results demonstrate that metabolic interactions between hydrocarbons and chloroalkene may lead to a modification of the biological response to these compounds.

12

Metoda oznaczania n-heksanu na stanowiskach pracy

Kozieł E., Hibner Z.

Aparatura Badawcza i Dydaktyczna

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2000

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T. 5, nr 1

39--45

PL

Opisano metodykę oznaczania n-heksanu w środowisku pracy przy zastosowaniu chromatografii gazowej z detekcją płomieniową jonizacyjną. Do oznaczania n-heksanu, w obecności jego izomerów i innych związków, zastosowano kolumnę kapilarną PE-1 (60 m x 0,32 mm x 0,1 Fm). Próbkę pobierano przez adsorpcję na węglu aktywnym i anality desorbowano disiarczkiem węgla.

EN

The procedure of the determination of n-hexane in working environment, using gas chromatography with flame — ionization detection is described. A capillary column PE-1 (60m x 0,32 mm x 0,1 µm) was used for the determination of analysed compound in the presence of its isomers and other compounds. A sample was adsorbed on activated carbon and desorbed using carbon disulphide. The method is aplicable for the determination of n-hexane on the level of 0,25 NDS value, i.e. 25 mg/m3, in the presence of other isomers of hexane.

13

n-Heksan : metoda oznaczania

Kozieł E., Hibner Z.

Podstawy i Metody Oceny Środowiska Pracy

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1999

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Nr 22

101--104

EN

The method is based on the adsorption of n-hexane vapours on active charcoal, desorption with carbon disulfide and GC analysis of the obtained solution. The determination limit of the method is 25 mg/m3.