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In this work, supported Cu–Ni bimetallic catalysts were synthesized and evaluated for the in situ hydrogenation and decarboxylation of oleic acid using methanol as a hydrogen donor. The supported Cu–Ni alloy exhibited a significant improvement in both activity and selectivity towards the production of heptadecane in comparison with monometallic Cu and Ni based catalysts. The formation of the Cu–Ni alloy is demonstrated by high-angle annular dark-field scanning transmission electron microscopy (HADDF-STEM), energy dispersive X-ray spectroscopy (EDS-mapping), X-ray diffraction (XRD) and temperature programmed reduction (TPR). A partially oxidized Cu in the Cu–Ni alloy is revealed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) following CO adsorption and X-ray photoelectron spectroscopy (XPS). The temperature programmed desorption of ethylene and propane (ethylene/propane-TPD) suggested that the formation of the Cu–Ni alloy inhibited the cracking of C–C bonds compared to Ni, and remarkably increased the selectivity to heptadecane. The temperature programmed desorption of acetic acid (acetic acid-TPD) indicated that the bimetallic Cu–Ni alloy and Ni catalysts had a stronger adsorption of acetic acid than that of the Cu catalyst. The formation of the Cu–Ni alloy and a partially oxidized Cu facilitates the decarboxylation reaction and inhibits the cracking reaction of C–C bonds, leading to enhanced catalytic activity and selectivity.

In this study, the deoxygenation of stearic acid over a series of Ni-based catalysts in the absence of hydrogen and solvents was investigated. Ni/Al2O3, Ni/TiO2, Ni/ZrO2, and Ni/AC (activated carbon) were synthesized using the wetness impregnation method, and Ni/AC showed the best activity for deoxygenation. X-ray diffraction, transmission electron microscopy, H2 temperature-programmed reduction, and N2 adsorption–desorption analyses revealed that Ni had an average particle size of about 9.6 nm with good crystallinity, the largest surface area and strong Ni–carrier interactions in Ni/AC. These properties of Ni/AC contributed to its good deoxygenation activity. Ni/AC produced hydrocarbons (71.4% yield) such as heptadecane, heptadecene, aromatics, and cracking paraffins under optimized reaction conditions. Furthermore, it was found that the deoxygenation of stearic acid over Ni/AC in the absence of hydrogen and solvent proceeds mainly via decarbonylation.

A novel Peltier-element-based adiabatic scanning calorimeter has been used to investigate the temperature dependence of the specific heat capacity and the specific enthalpy for n-alkanes heptadecane and nonadecane and for a set of their binary mixtures. The measurements have covered a broad temperature range from well into the ordered solid phase to well into the liquid phase. The analysis of the experimental data has allowed us to obtain accurate results for the phase transition temperatures, the transition enthalpies and the specific heat capacity values in the different phases.

In nanoporous rocks, potential size exclusion and fluid-rock interactions in nano-sized pores and pore throats may turn the rock into a semi-permeable membrane, hindering the transport of certain molecules while allowing other molecules to pass freely. In this work, to investigate whether Niobrara samples possess such selectivity to a liquid hydrocarbon mixture, we conducted core-flow tests by pumping a binary hydrocarbon mixture (decane, C10 and heptadecane, C17) into Niobrara samples and analyzing the produced fluid compositions. Molecular dynamics simulation of C10 and C17 adsorption on calcite surfaces using all-atom models was performed to help understand the mechanisms of the experiments. Experimental results show that the transport of heavier component (C17) was noticeably hindered, with a decrease of its mole fraction in the produced fluid and an increase in the upstream injection fluid, demonstrating the presence of selective hindrance. Simulation results indicate that, for a calcite surface in equilibrium with the binary mixture of C10 and C17, more C17 molecules adsorb on the calcite surface than C10. Compositional change of fluid upstream of the sample and a mole balance calculation suggest that size exclusion should also exist.

Codium adhaerens from the Adriatic Sea (Croatia) was comprehensively investigated regarding less polar compounds for the first time. Although there are several phytochemical studies on C. adhaerens from other regions, this is the first report on volatile organic compounds (VOCs) from fresh (FrCa) and air-dried (DrCa) samples. The novelty is also related to its targeted antioxidant potential in vitro and in vivo. The main aims were to: (a) identify and compare VOCs of FrCa and DrCa obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD), (b) determine fatty acid (FA) composition of freeze-dried sample (FdCa), (c) determine the composition of less polar fractions of FdCa by high-performance liquid chromatography–high-resolution mass spectrometry with electrospray ionisation (UHPLC-ESI-HRMS), and (d) comprehensively evaluate the antioxidant activity of the fractions by four in vitro assays and in vivo zebrafish model (including embryotoxicity). Significant changes of VOCs were found after air drying. ω6 FAs were present in higher content than ω3 FAs indicating C. adhaerens as a good source of dietary polyunsaturated FAs. The results obtained in vivo correlate well with in vitro methods and both fractions exerted similar antioxidative responses which is in agreement with the high abundance of present biomolecules with known antioxidant properties (e.g., fucoxanthin, pheophytin a, and pheophorbide a). These results suggest that C. adhaerens might be a potent source of natural antioxidants that could be further used in the research of oxidative stress-related diseases.

The reactions to produce liquid biofuels from a palm fatty acid distillate (PFAD) under hydrogen absence were carried out using 10 wt% NiO/zeolite (Ni/Zeo), 10 wt% Co3O4/zeolite (Co/Zeo), and 10 wt% (NiO + Co3O4)/zeolite (NiCo/Zeo) as catalysts. The zeolite was synthesized by a thermal and chemical treatment from natural clay, obtaining a zeolite A and sodalite mixture. Catalytic activity was evaluated as a function of reaction temperature (250, 300, and 350 °C) during 0.5 h and using 5 wt% of catalyst. The reaction products were classified as organic liquid products (OLPs), gaseous products, and solid waste. The OLPs fractions were separated by fractional distillation, and the products were identified and quantified using gas chromatography coupled to a mass spectrometer detector (GC-MS). The results showed yields to OLPs above 50% for all catalysts and temperatures. However, the highest yield to OLPs of 67.9% was reached with a NiCoZeo catalyst at 300 °C. In this reaction, a higher yield to hydrocarbons was obtained (84.8%), indicating a cooperative effect between Ni and Co in the catalyst. Hydrocarbons such as heptadecane (C17H36), pentadecane (C15H26), and other alkanes-alkenes with lower carbon chains were the main products. Therefore, deoxygenation of PFAD using a low-cost Ni-Co catalyst was shown to be an economic and viable way to produce diesel-type biofuels.

In this work, the applicability of eco-friendly choline chloride-based deep eutectic solvents (DESs) in the extraction of β-phenylethyl alcohol (PEA) as the main ingredient of red rose oil from Iranian red rose blossoms have been investigated for the first time and the results were compared to the several conventional organic solvents including tetrahydrofuran (THF), n-hexane, cyclohexane, methyl ethyl ketone (MEK) and isobutyl alcohol (iBuOH). The Iranian red rose oil compositions were determined using the gas chromatography (GC) technique. The main compounds of Iranian red rose oil were PEA (63–69%), citronellol (10–11%), geraniol (8–9%), heptadecane (0.5–5%), nerol (4–5%), nonadecane (0.5–2.5%), methyl eugenol (2–3%), eugenol (2.5–3%) and benzyl alcohol (0.9–1.1%). The results indicate that choline chloride:sucrose DES with (1:2) mole ratio performs better in the extraction of PEA than the conventional solvents. The results were confirmed using Hansen solubility parameters (HSP) and the activity coefficient model. The extracted red rose oil was encapsulated for the first time in N-butyl palmitate/stearate (BPS) with a 24.6 °C melting point as the thermosensitive shell. The narrow particle size distribution of the produced nanocapsules of (70–550) nm were found.

The oxidation of fatty acids affects the aroma of foxtail millet porridge. However, the relationship between volatile compounds and fatty acid precursors is still unclear. Gas chromatography-mass spectrometry was used to detect the volatiles of foxtail millet porridge. The results showed that 23 volatiles were detected, and the content of most aldehydes increased after cooking. The free fatty acid content increased 0.8–1.2-fold, while the total fatty acid content decreased 0.1–0.4-fold. Modeling experiments showed that palmitic acid had no contribution to the formation of volatile compounds, whereas stearic acid produced heptadecane by decarboxylation. Moreover, oleic acid produced octanal, nonanal, nonane, and decanal. Linoleic acid produced hexanal, (Z)-2-heptenal, (E)-2-octenal, 2-pentyl-furan, 3-ethyl-2-methyl-1,3-hexadienal, (E,E)-2,4-decadienal, N-phenyl-benzenamine, 2-n-butylfuran, and benzaldehyde. Linolenic acid produced (E,E)-2,4-decadienal, decanal, benzaldehyde, tetradecane, hexadecane, 2,6,10-trimethyl-pentadecane, and heptadecane. Unsaturated fatty acids play important roles in the formation of the volatiles of foxtail millet porridge.

In this work, the efficiency of extracting algae from culture medium using magnetic nanoparticles (MNPs), converting the algal/particle slurry to biocrude using hydrothermal liquefaction (HTL), and successfully recycling the MNPs from the char phase was fully demonstrated for the first time. MNPs were synthesized by coprecipitation and used to extract algae from aqueous phase at a separation efficiency (SE) of 99%. The SE was optimized at pH 4. Liquefaction of algal/MNPs slurry gave a biocrude yield of 37.1% while algae only yielded 23.2%. The percentage areas in the GC-MS chromatogram corresponding to hydrocarbons (HCs) in Zn-ferrite catalyzed and uncatalyzed biocrude were 46.5% and 19.9%, respectively, while the percentage areas of heptadecane from Zn-ferrite catalyzed and uncatalyzed biocrude were 37.8% and 10%, respectively. Furthermore, the percentage area of heteroatom compounds in biocrude reduced substantially when liquefaction was done in the presence of Zn/Mg ferrites. The nanoparticles were recovered from biochar by sonication and recycled at a SE of 96.1%. Recycling of MNPs for magnetic separation of algae and catalytic HTL could lower the cost of microalgae harvesting and improve the yield and quality of biocrude. This could potentially reduce the cost of advanced biofuel processing from microalgae, making them more affordable in comparison to petroleum-derived fuels.

In this study, n -heptadecane as a phase change material was microencapsulated with a starch wall for thermal energy storage applications. The effect of encapsulation parameters including mixing rate, reaction time, starch to n -heptadecane mass ratio and starch to water mass ratio were investigated on the microcapsule properties. The chemical compositions of the prepared microcapsules were characterized by Fourier transform infrared spectroscopy. The optical microscopy and scanning electron microscopy observations showed that the spherical microcapsules with a rough and intact shell were formed. The particle size analysis and thermogravimetric analysis were utilized to study the microcapsule structural properties and to explain the microencapsulation mechanism. The mechanism of the microencapsulation involved a multi-stage adsorption of starch components started with the migration of the amylose-lipid complexes onto the n -heptadecane droplets. The microencapsulated n -heptadecane with the starch wall had high melting and solidifying enthalpies and a proper thermal reliability, according to the results of differential scanning calorimetry. The prepared microcapsules can be used in different matrices, such as surface coatings, sheets, and liquid media.

Recently, the decarboxylation of oleic acid (9(Z)-octadecenoic acid) catalyzed by triruthenium dodecacarbonyl, Ru3(CO)12, to give a mixture of heptadecenes with concomitant formation of other hydrocarbons, heptadecane and C17 alkylbenzenes, was reported. The product mixture, consisting of about 77% heptadecene isomers, 18% heptadecane, and slightly >4% C17 alkylbenzenes, possesses acceptable diesel fuel properties. This reaction is now applied to other fatty acids of varying chain length and degree of saturation as well as double-bond configuration and position. Acids beyond oleic acid included in the present study are lauric (dodecanoic), myristic (tetradecanoic), palmitic (hexadecanoic), stearic (octadecanoic), petroselinic (6(Z)-octadecenoic), elaidic (9(E)-octadecenoic), asclepic (11(Z)-octadecenoic), and linoleic (9(Z),12(Z)-octadecadienoic) acids. Regardless of the chain length and degree of unsaturation, a similar product mixture was obtained in all cases with a mixture of alkenes predominating. Monounsaturated fatty acids, however, afforded the alkane with one carbon less than the parent fatty acid as the most prominent component in the mixture. Alkylbenzenes with one carbon atom less than the parent fatty acid were also present in all product mixtures. The number of isomeric alkenes and alkylbenzenes depends on the number of carbons in the chain of the parent fatty acid. With linoleic acid as the starting material, the amount of alkane was reduced significantly with alkenes and alkylaromatics enhanced compared to the monounsaturated fatty acids. Two alkenes, 9(E)-tetradecene and 1-hexadecene, were also studied as starting materials. A similar product mixture was observed but with comparatively minor amount of alkane formed and alkene isomers dominating at almost 90%. The double-bond position and configuration in the starting material do not influence the pattern of alkene isomers in the product mixture. The results underscore the multifunctionality of the Ru3(CO)12 catalyst, which promotes a reaction sequence including decarboxylation, isomerization, desaturation, hydrogenation, and cyclization (aromatization) to give a mixture of hydrocarbons simulating petrodiesel fuels. A reaction pathway is proposed to explain the existence of these products, in which alkenes are dehydrogenated to alkadienes and then, under cyclization, to the observed alkylaromatics. The liberated hydrogen can then saturate alkenes to the corresponding alkane.

Purpose. To analyse the qualitative and quantitative composition of volatile organic substances (VOS) in the petals of six species of dog-rose in the collection of M. M. Gryshko National Botanic Garden of the NAS of Ukraine for further bree­ding. Methods. Volatile organic substances were obtained by steam distillation. VOS was determined using gas chromato­graphy (Chromatograph Agilent Technologies 6890). Results. The qualitative and quantitative composition of volatile organic substances in the petals in such species as Rosa L. (R. roullettii HCh (Correvon), R. multiflora Thunb., R. pimpinellifolia L., R. canina L., R. centifolia L., R. rugosa Thunb.) was investigated. According to the results of the research, 105 VOS were discovered in the dog-rose petals, among which 11 were not identified. The dog-rose petals of identified VOC contained 16 components which share exceeds 5%, 31 – was ranging from 1% to 5%, 47 – was less than 1%. They belonged to different groups including monoterpenoids, sesquiterpenoids, sesquiterpene alcohols, saturated unbranched hydrocarbons etc. The largest number of components were identified in the petals of R. roulettii (49) and R. centifolia (45), while the number of identified components in species R. multiflora (33), R. rugosa (31) and R. canina (30) was relatively smaller. All studied dog-rose species were characterized by the presence of such saturated unbranched hydrocarbons as decan, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane, heneicosane, tricosane, tetracosane, pentacosane, heptocosane, hentriacontane. Triterpene hydrocarbon squalene is the important component of the VOS complex in dog-rose pen tals. b-phenylethyl alcohol to be one of the main components of the rose essential oils was found during investigation in the following four dog-rose species as R. centifolia (0.61%), R. pimpinellifolia (3.56%), R. rugosa (4.24%), and R. multiflora (5.43%). Significant content of dihydro-b-ionol (18.46%), dihydro-b-ionone (0.69%), thias­piran A (1.35%), and thiaspiran B (2.17%) were revealed in the petals of R. roulettii, which also have an influence on the aromatic bouquet of the rose oil. Conclusions. For the first time, 105 volatile organic substances were found in the petals of six species of dog-rose, 11 of which were not identified. It was found out that the largest number of components were identified in the petals of R. roulettii (49) and R. centifolia (45). The number of VOS identified in species R. multiflora (33), R. rugosa (31), and R. canina (30) was relatively smaller. Component composition of VOS in the petals of studied dog-rose species is an important constituent in breeding investigations of prospective producers for the various purposes of use.

The Al2O3 supported monometallic Co, Ni and Mo and bimetallic CoMo and NiMo catalysts were compared in rapeseed oil hydrodeoxygenation (HDO) reaction after in situ sulfidation. The reaction was described by five pseudo-first order rate constants (k 1–k 5) for the simplified reaction scheme: triglycerides (Tgs) to octadecane (k 1); Tgs to oxygenates (Oxs; i.e., sum of fatty acids, fatty alcohols, and esters of fatty acids and fatty alcohols) (k 2); Tgs to heptadecane (k 3); Oxs to octadecane (k 4), and Oxs to heptadecane (k 5). The empirical pseudo-first order rate constant of the hydrocarbons (Hcs) product formation (k Hc ) increased in the order Ni/Al2O3 ~ Co/Al2O3

An enzymatic method to tenderise golden pomfret (GP, Trachinotus blochii) flesh by marinating with bromelain (BML) solution was developed to produce GP fish balls with a texture similar to those of yellowtail fusilier (YF, Caesio cuning). Treatment with BML reduced the hardness, chewiness and gel strength significantly but increased the resilience of GP fish balls. As a result, 0.4% (enzyme-substrate ratio, w/w) BML-treated GP fish balls had the same texture properties as YF fish balls. Meanwhile, changes in myofibrillar proteins in the fish balls were determined using sodium dodecyl sulphate polyacrylamide gel electrophoresis, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and atomic force microscopy. The results indicated that BML degraded myosin light chain and troponin T effectively, without affecting actin. BML treatment generated protein fragments with significantly smaller sizes, thereby improving the tenderness of the flesh. The length, width and height of the myofibrils from 0.4% BML-treated fish ball were 6.42, 1.52 and 1.48 μm, respectively, which were not significantly different from the myofibrils of YF fish balls, indicating that the similar nanostructure determined the comparable texture properties. Gas chromatography-mass spectrometry analysis showed that 0.4% BML decreased the amount of hexanal, hexadecane, 1-octen-3-ol and 2,6,10,14-tetramethylpentadecane but increased the ratio of heptadecane from 18.14 to 38.23% in the treated fish balls, making the flavour of 0.4% BML-treated GP fish balls similar to that of YF balls. Overall, the results suggest that 0.4% BML-tenderised GP could be a promising alternative to YF to produce quality fish balls.

The hydrotreatment of oleic acid in a green reaction media to produce the major hydrodeoxygenation product octadecane using a 6 wt% nano Fe loaded Fe/SBA-15 as catalyst was demonstrated in this study. The data show that hexane containing pressurized CO2 could dictate the selectivity of the hydrotreatment of oleic acid with high selectivity for hydrodeoxygenation over decarboxylation/decarbonylation. In addition, hexane containing pressurized CO2 could offer beneficial effects including reduction of viscosity of the solution and increase of H2 solubility. As a result, uniform dispersion of the catalyst occurred in the solution and the diffusion resistances were reduced as well due to the increase in mass transfer. At the best operating condition of 290 °C, 6 h, 30 bars H2 and 40 bars CO2, an octadecane yield of 83.3% and a heptadecane yield of 8.7% were observed when compared to 65% and 15%, which were the yields in the absence of CO2. The effects of three independent operation variables namely, temperature, CO2 pressure and time and their interactions on the hydrotreatment of oleic acid were studied using a central composite design and response surface methodology. The results showed that all these three variables were significant factors for increasing the yield of octadecane while CO2 pressure was the most significant variable in decreasing the yield of heptadecane, the major decarboxylation/decarbonylation product.

The role of solvents in the conversion of oleic acid over Pt/C was studied. Three solvent systems (solvent-free, water, and dodecane systems) were employed for the conversion of oleic acid over Pt/C at 350 °C. Decarboxylation, hydrogen transfer, and aromatization were observed in these three reaction systems. In comparison to the non-solvent reaction system, much slower decarboxylation and aromatization rates and fewer heptadecane and aromatic products were observed in the hydrothermal and dodecane reaction systems. The decarboxylation and aromatization rates and yields of heptadecane and aromatics decreased with increased dodecane loading in the dodecane reaction system, and the decarboxylation and aromatization rates and yields of heptadecane and aromatics significantly decreased with the increase of water in the hydrothermal reaction system. The effects of solvent loading, catalyst loading, and reaction time on the reactions (decarboxylation, hydrogen transfer, and aromatization) were investigated. The...

Alumina supported NiMo catalysts were synthesized. The prepared NiMo catalysts were activated by DMDS in a sulfidation process and characterized. The sulfided NiMo catalysts were next used in hydrodeoxygenation (HDO) of oleic acid in a batch reactor. Afterward, the NiMo catalysts were recovered and used in another set of HDO reactions of oleic acid under the same conditions used in the previous HDO reactions. After the HDO experiments, the active phase and deposited coke on spent catalysts were characterized. The results indicated that higher concentrations of DMDS promoted the production of heptadecane (C17) but had no effect on the production of octadecane (C18). Moreover, the XPS results revealed the promotional effect of DMDS concentration on maintenance of the sulfidity of the catalysts. In addition, the results for the experiments with the second run catalyst revealed a clear deactivation due to increased coke depositions. Furthermore, after two repeated experiments with first run and second run cat...

The effect of various reaction temperature on the hydrocracking of Cerbera manghas oil to produce a paraffin-rich mixture of hydrocarbons with Co-Ni/HZSM-5 as doubled promoted catalyst were studied. The Co-Ni/HZSM-5 catalyst with various metal loading and metal ratio was prepared by incipient wetness impregnation. The catalysts were characterized by XRD, AAS, and N 2 adsorption-desorption. Surface area, pore diameter, and pore volume of catalysts decreased with the increasing of metals loading. The hydrocracking process was conducted under hydrogen initial pressure in batch reactor equipped with a mechanical stirrer. The reaction was carried out at a temperature of 300-375 o C for 2 h. Depending on the experimental condition, the reaction pressure changed between 10 bar and 15 bar. Several parameters were used to evaluate biofuel produced, including oxygen removal, hydrocarbon composition and gasoline/kerosene/diesel yields. Biofuel was analyzed by Fourier Transform Infrared Spectroscopic (FTIR) and gas chromatography-mass spectrometry (GC-MS). The composition of hydrocarbon compounds in liquid products was similar to the compounds in the gasoil sold in unit of Pertamina Gas Stations, namely pentadecane, hexadecane, heptadecane, octadecane, and nonadecane with different amounts for each biofuel produced at different reaction temperatures. However, isoparaffin compounds were not formed at all operating conditions. Pentadecane (n-C15) and heptadecane (n-C17) were the most abundant composition in gasoil when Co-Ni/HZSM-5 catalyst was used. Cerbera Manghas oil can be recommended as the source of non-edible vegetable oil to produce gasoil as an environmentally friendly transportation fuel. Copyright © 2017 BCREC Group. All rights reserved Received: 20 th May 2016; Revised: 30 th January 2017; Accepted: 10 th February 2017 How to Cite: Marlinda, L., Al-Muttaqii, M., Gunardi, I., Roesyadi, A., Prajitno, D.H. (2017). Hydrocracking of Cerbera manghas Oil with Co-Ni/HZSM-5 as Double Promoted Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis , 12 (2): 167-184 (doi:10.9767/bcrec.12.2.496.167-184) Permalink/DOI : http://dx.doi.org/10.9767/bcrec.12.2.496.167-184

Long-chain alkanes are a type of important intermediate-volatile organic compounds (IVOCs) in the atmosphere, which contribute to a large proportion of secondary organic aerosol (SOA). However, the optical properties of SOA derived from long-chain alkanes remain poorly understood. Here, we investigate the refractive index (RI) of SOA derived from photo-oxidation of dodecane (C12), pentadecane (C15) and heptadecane (C17) under low-NOx and high-NOx conditions with the absence or presence of inorganic aerosol seeds. The RIs of these SOAs are found to be in the range of 1.33 to 1.57 at the wavelength of 532 nm. The results from mass spectroscopy indicate that both reaction mechanisms influenced by NOx level and gas-particle partitioning influenced by seeds have important impact on the chemical compositions of SOAs, which further influence the optical properties like RI. Finally, by comparing the RI values to other literature and model results, we suggest that various RIs of SOAs derived from long-chain alkanes should be applied in atmospheric and climate models.

Efficiency of Enterobacter cloacae KU923381 isolated from petroleum hydrocarbon contaminated soil was evaluated in batch culture and bioreactor mode. The isolate were screened for biofilm formation using qualitative and quantitative assays. Response surface methodology (RSM) was used to study the effect of pH, temperature, glucose concentration, and sodium chloride on diesel degradation. The predicted values for diesel oil degradation efficiency by the statistical designs are in a close agreement with experimental data (R 2 = 99.66%). Degradation efficiency is increased by 36.78% at pH = 7, temperature = 35°C, glucose = 5%, and sodium chloride concentration = 5%. Under the optimized conditions, the experiments were performed for diesel oil degradation by gas chromatographic mass spectrometric analysis (GC-MS). GC-MS analysis confirmed that E. cloacae had highly degrade hexadecane, heptadecane, tridecane, and docosane by 99.71%, 99.23%, 99.66%, and 98.34% respectively. This study shows that rapid bioremoval of hydrocarbons in diesel oil is acheived by E. cloacae with abet of biofilm formation. The potential use of the biofilms for preparing trickling filters (gravel particles) for the degradation of hydrocarbons from petroleum wastes before their disposal in the open environment is highly suggested. This is the first successful attempt for artificially establishing petroleum hydrocarbon degrading bacterial biofilm on solid substrates in bioreactor.

Fractional conversion of natural algae cyanobacteria from Taihu Lake was conducted. The raw Taihu Lake algae (TLA) and pretreated samples were pyrolyzed at 290 °C and 450 °C according to the TGA results. Extraction of lipids or saccharides from the TLA was performed as a pretreatment to obtain lipid extracted algae (LEA) or saccharide extracted algae (SEA). The total yields of bio-oil from fractional pyrolysis were 40.9 wt% from TLA, 42.3 wt% from LEA, and 48.5 wt% from SEA. From TLA, the major components of the bio-oil were fatty acids, amides and hydrocarbons (heptadecane) at 290 °C whereas those at 450 °C were phenols and C10–C15hydrocarbons. Following the lipid extraction, acids, amides and indoles accounted for a large proportion at 290 °C, while the main products obtained at 450 °C were phenols, indoles and pyrroles. It is worth mentioning that the yield of bio-oil from the LEA had increased, and the composition of the bio-oil was simplified. Moreover, the average molecular weight of the bio-oil obtained from LEA had decreased. Interestingly, the extraction of saccharides inhibited pyrolysis of the lipids, so the distribution of the bio-oil from SEA changed only a little. Fractional pyrolysis of pretreated microalgae not only increased the bio-oil yield but also improved the quality of the bio-oil.

Kinetics in the hydrodeoxygenation of stearic acid was investigated over Ni-γ-Al2O3 catalyst. The main variables were catalyst prereduction mode, reaction atmosphere and hydrogen pressure in the total pressure range of 7–30 bar. The results revealed that high conversion, 99% in 360 min and high selectivity to heptadecane, 97% were achieved at 300 °C under 30 bar total pressure. The yield of an intermediate hydrogenation product, stearyl alcohol increased with increasing hydrogen pressure as expected. Higher reaction rates and conversion levels were also achieved with the prereduced catalyst and carrying out the reaction in the presence of hydrogen. As a comparison to stearic acid, hydrodeoxygenation of tall oil fatty acids, an industrial feedstock was successfully demonstrated with Ni-γ-Al2O3 under the same conditions. A kinetic model including the pressure effect was derived and applied for data with Ni-γ-Al2O3 as well as for Pd/C, Ni-H-Y-80 and Ni/SiO2 catalysts. The model described well the kinetic data.

Sulfur-free Ni supported on H-Y zeolites, γ-Al 2 O 3 and SiO 2 synthesized by the wet impregnation method, and Pd/C were tested in hydrodeoxygenation (HDO) of stearic acid. The catalysts were forming n- heptadecane except Ni/H-Y-80, which was producing n- heptadecane and n- octadecane. Ni/H-Y 80 and Pd/C were tested on HDO of fatty acid methyl esters from chlorella, tall oil fatty acids, and animal fat. The reactions converting the substrates to the final products followed the path from unsaturated esters to acids, with hydrogenation of the latter into alcohols (i.e., stearyl alcohol), and finally formation of hydrocarbons. Ni/H-Y-80 permitted rapid and complete conversion into hydrocarbons, while Pd/C displayed 5–20 times lower turnover frequency, producing saturated intermediates along with hydrocarbons. The catalyst reusability of Ni supported on Y zeolites was studied by recycling and regenerating the spent catalyst from fatty acid HDO. The catalysts demonstrated the possibility of restoring the rates per unit of surface area after regeneration. Catalysts used in HDO of different feedstocks were investigated by thermogravimetric analysis, inductively coupled plasma-optical emission spectroscopy, transmission electron microscopy, surface area measurements, and pore size analysis.

Inspired by the interest in the confinement effect on polymorphism of alkane mixtures, phase behaviors of a hexadecane–heptadecane (n-C16H34–C17H36, C16–C17) binary system in the bulk and in nanopores of controlled porous glasses (CPGs) are investigated using differential scanning calorimetry (DSC) and temperature-dependent powder X-ray diffraction (XRD). As reported, bulk C16–C17 mixtures form two intermediate phases with monoclinic (Mdci) and orthorhombic (Op) structures in a low temperature range and rotator phase RI in high temperature range. In the pores of CPG (300 nm), these solid phases appear in the temperatures slightly below the bulk system. The RI one-phase region extends a bit in temperature range in the mixtures of high C17 components. In CPG (8.1 nm), the solid phases come up in much lower temperatures than the bulk. The rotator RI is found in a larger range of the temperature and composition than the bulk and in CPG (300 nm). A new phase, the rotator RII, is observed in a narrow temperature range of high C17 composition just before melting. XRD analysis shows diffractions from the alkane layered ordering in CPG (300 nm) with a more roughened layer surface than the bulk. Lamellar stacking of the solids in CPG (8.1 nm) is heavily perturbed. The variation in the polymorphism of C16–C17 mixtures in the nanopores is associated with the reduced ordering of the molecule arrangements. These results can help to understand the influence of confinement effect on binary mixtures of alkanes, the chain molecules.

Marine ascidians contain potential bioactive compounds, which exhibit significant pharmacological activities. In the present study, the MeOH extract of Didemnum sp. was subjected to FT-IR, GC-MS analysis, the possible interactions with EGFR through docking analysis and in vitro cytotoxic activity against KB (Human oral cancer) cell line were also studied. The FT-IR analysis of Didemnum sp. revealed a number of functional groups namely, aromatics, amines, aldehydes, alcohols, alkyl halides, alkynes, alkanes, phenols and carboxylic acids. The GC-Ms analysis showed 30 peaks reflecting L-Ascorbic acid, 6-octadecanoate (49.16%), l-(+)-Ascorbic acid 2, 6-dihexadecanoate (12.88%), Oleic Acid (1.19%), Benzothiazole (1.09%) Heneicosane (0.72 %), Hexadecanol (0.49%), Heptadecane (0.47%), Eicosane (0.40%) and n-Decanoic acid (0.36%). The docking analysis showed minimal energies for L-Ascorbic acid, 6-octadecanoate (−7.4 kcal/mol), Cholesta-5, 7-dien-3.beta.-ol (-7.3 kcal/mol), l-(+)-Ascorbic acid 2, 6-dihexadecanoate (−6.5 kcal/mol) and Ethanol, 2-(9-octadecenyloxy)-, (Z) (−6.3 kcal/mol) against EGFR (Epidermal growth factor receptor), which confirmed the possible binding interactions. The obtained bioactive compounds of Didemnum sp. could be an interesting candidature against cancer.

While we optically observed the pressure-induced transformation between the solid phases of SII and SI of n-heptadecane, of which p–T diagram has a parallel and wide gap between the coexistence lines between liquid–SI and between SI–SII (the same as that of n-pentadecane), we found that the SII crystal of n-heptadecane is stable even below the coexisting line between the SI and liquid, as is that of n-pentadecane. Fortunately, we can easily distinguish the SI crystal, of which morphology shows a hexagonal thin plate with very round corners, from the SII crystal, of which morphology shows a long and narrow pillar-like form in the liquid. Here, we report on the epitaxial growth of SI filmy crystals of n-heptadecane on its SII crystal in the p–T condition of 40 MPa and 30 °C. Although we could not observe the epitaxial growth of n-pentadecane, we could observe the clear epitaxial growth of n-heptadecane in the mixed liquid of n-pentadecane and n-heptadecane. Growth suppression by n-pentadecane brings about clear crystal shapes. Moreover, the epitaxially growing SI filmy crystals of n-heptadecane form a disk-like vessel which put its pillar-like SII crystal between the filmy crystals. If several billion years ago this vessel had been formed in a mixed drop of normal alkanes drifting about above the bottom of a deep sea, where the p–T condition was 40 MPa and 30 °C, the vessel might be seen as a cradle of primitive life.

The bioremediation efficiency of petroleum hydrocarbons in natural soil-water systems is regulated by active microbial populations and other system parameters. Relevant factors include the transfer rate of petroleum contaminants from a medium into microorganisms, the partitioning behavior of contaminants from water into the soil organic matter (SOM), and the influence of the dissolved organic matter (DOM) on the contaminant level in water. The objectives of this study was aimed to determine the correlation among bioavailability of petroleum hydrocarbons, SOM content, and DOM level in soil-water systems. Heptadecane, pristane, and decylcyclohexane were selected as model hydrocarbon contaminants. The bioavailability of target contaminants in soil was examined using soils of different SOM contents (2% and 20%) in slurry bioreactors. In addition, the contaminant bioavailability as affected by various DOM levels (0–100 mgC/L) was also examined. The results showed that the SOM content affected the degrading rate of hydrocarbons significantly, where the rate constant was 4 times higher in 2% SOM microcosm than in the 20% SOM bioreactor for heptadecane degradation. Similarly, the pristane degrading efficiency after 240 h operation was 95% for the 2% SOM microcosm and only 38% for the 20% SOM microcosm. The hydrocarbon degradation rates in water phase were found to be enhanced by the added DOM level. A positive correlation existed between the contaminant bioavailability and the contaminant level in water as impacted by the SOM content in soil and the DOM level in water.

The focus of present study is on Codium bursa collected from the Adriatic Sea. C. bursa volatiles were identified by gas chromatography and mass spectrometry (GC-FID, GC-MS) after headspace solid-phase microextraction (HS-SPME), hydrodistillation (HD), and supercritical CO2 extraction (SC-CO2). The headspace composition of dried (HS-D) and fresh (HS-F) C. bursa was remarkably different. Dimethyl sulfide, the major HS-F compound was present in HS-D only as a minor constituent and heptadecane percentage was raised in HS-D. The distillate of fresh C. bursa contained heptadecane and docosane among the major compounds. After air-drying, a significantly different composition of the volatile oil was obtained with (E)-phytol as the predominant compound. It was also found in SC-CO2 extract of freeze-dried C. bursa (FD-CB) as the major constituent. Loliolide (3.51%) was only identified in SC-CO2 extract. Fatty acids were determined from FD-CB after derivatisation as methyl esters by GC-FID. The most dominant acids were palmitic (25.4%), oleic (36.5%), linoleic (11.6%), and stearic (9.0%). FD-CB H2O extract exhibited better antifungal effects against Fusarium spp., while dimethyl sulfoxide (DMSO) extract was better for the inhibition of Penicillium expansum, Aspergillus flavus, and Rhizophus spp. The extracts showed relatively good antifungal activity, especially against P. expansum (for DMSO extract MIC50 was at 50 &micro, g/mL).

The experimental research of heptadecane’s crystallization front propagation is carried up on horizontal directed crystallization model. The temperature distributions on free surface are measured during crystallization front propagation process using thermal imager and thermocouples. The time dependence of crystallization front form was investigated using digital video recording.

Molecular and isotopic analysis of sediments from archaeological combustion features is a relatively new area of study. Applications can inform us about ancient pyro-technologies and patterns of animal exploitation in a wide range of human contexts, but may be particularly informative with regard to ancient hunter-gatherers. Our analyses of sediments from experimental bone and wood fires, and from controlled laboratory heating sequences, provide fine-grained data on the formation and location of biomarkers from pyrolyzed animal fats in hearths. Integrating microstratigraphic, molecular, and isotopic data can improve recognition of bone fires in archaeological contexts, perhaps even where bone preservation is poor. Experimental bone fires produced an upper layer of calcined bone above a thin layer of tarry black amorphous material coating mineral sediments. Mineral sediments beneath the black layer showed little alteration but high lipid content. Sampling for molecular and isotopic analysis should target the black layer as the bulk of pyrolyzed biomarkers are located here and stable isotope values are less affected than in the overlying layer of ash or calcined bone. The combined presence of certain symmetric and slightly asymmetric saturated long-chain ketones (14-nonacosanone, 16-hentriacontanone 16-tritriacontanone, and 18-pentatriacontanone), especially together with heptadecane (C17n-alkane), are molecular indicators of the thermal degradation of terrestrial animal fat. Formation and relative dominance of these molecules in hearth sediments relates to the initial prevalence of specific precursor fatty acids and can provide broad separations between sources. We suggest that separations could be further supported and expanded by combining stable isotope analysis of the same compounds.

The SPME-GC-MS analysis of the aroma components of Cephalanthera damasonium, Cephalanthera rubra, and Cephalanthera longifolia were reported. The main components found in C. damasonium were pentadecane, hexadecane, heptadecane and α-farnesene. The same compounds were found in the scent of C. rubra. Although C. damasonium and C. rubra have different pollination mechanisms, their spectrum of volatile compounds surprisingly does not differ significantly. In C. longifolia pentadecane and heptadecane were found together with cis-β-farnesene. As C. longifolia is allogamous, the differences in scent composition may play a role in pollinator attraction.

The safe disposal and eco-friendly management of distillery sludge discharged after anaerobic digestion of spent wash have become a serious global concern. The present paper aims to investigate the heavy metal phytoextraction potential of Ricinus communis L. thrive on dumped distillery sludge, which was slightly contaminated by heavy metals and organometallic co-pollutants. The results of physicochemical analyses of distillery sludge revealed the presence of high amounts of Fe (62856.32 mg kg−1), Zn (178.64 mg kg−1), Cu (648.39 mg kg−1), Cr (2.32 mg kg−1), Cd (1.89 mg kg−1), Mn (121.42 mg kg−1), Ni (14.32 mg kg−1), and Pb (18.51 mg kg−1) along with complex co-pollutants. The major recalcitrant organic pollutants detected by GC–MS/MS technique were octadecadienoic acid, 2,3-bis[(TMS)oxy]propyl ester; stigmasterol TMS ether; β -sitosterol TMS ether; docosanoic acid, TMS ester; and heptadecane, 2,6,10,15-tetramethyl. The phytoextraction potential revealed higher accumulation of Fe followed by Cu, Zn, Mn, Ni, and Pb, in root and shoot of R. communis L. It was also noted that the bioaccumulation factor (BAF) and translocation factor (TF) of all tested metals were found to be 1, respectively which showed strong evidence for high hyperaccumulation and translocation capabilities of this plant. Furthermore, the ultrastructural study of root tissues of R. communis L. showed the formation of multi-vacuoles, multi-nucleolus, and deposition of metal granules in the cell wall and on the plasma membrane’s periphery of roots as adaptive characteristics of plants thriving at organometallic contaminated sludge dumping site. Thus, the study showed a strong indication for the application of Ricinus communis L. as a biotechnological tool for in-situ phytoextraction and restoration of organometallic contaminated sites.

Upgrading fatty acids to hydrocarbons via deoxygenation is significant for the synthesis of high-grade biofuels. Developing economic reaction conditions without using noble metal-based catalysts in the absence of hydrogen and solvent has promising application prospects. Herein, carbon-coated bimetallic FeNi nanoparticles were prepared via an in-situ carbonization-reduction strategy using double-metal cyanide at different temperatures for the deoxygenation of stearic acid. The size of the alloy core and the thickness of the carbon shell were found to be easily adjusted by varying temperature. Compared with monometallic Fe/C and Ni/C catalysts, the alloy catalyst exhibits an obvious improvement in both the conversion of stearic acid and the selectivity of heptadecane. ATR-IR spectra show that the insertion of the inert Fe element into Ni nanoparticles can promote carboxylic acid group adsorption but restrain hydrocarbon group adsorption. The synergistic effect of Fe and Ni elements leads to the promotion of direct decarboxylation of stearic acid and suppression of the C–C cracking reaction. Among different alloy catalysts studied, FeNi@C-800 exhibits the greatest catalytic performance with a 99.9% conversion of stearic acid and 76.8% selectivity for heptadecane. Furthermore, the catalyst can still maintain a stable catalytic performance against the leaching and ripening of metal through the protection afforded by the carbon shell. This work not only provides a powerful reaction system for the decarboxylation of stearic acid but also demonstrates an alternative catalyst to noble metals based on a convenient carbonization-reduction strategy.

Pyrolysis of brown grease to hydrocarbon products was performed in a pressure reactor. Compared to our previous work at atmospheric pressure, higher reaction temperatures could be achieved. These resulted in shorter reaction times, reduced formation of undesirable ketone byproducts, and a higher percentage of the most valuable light hydrocarbon products. Higher temperatures did, however, increase the percentage of gas products at the expense of liquid products. The major liquid products are alkanes ranging from heptane to heptadecane, with smaller amounts of cycloalkanes, and in some cases, aromatic compounds.

Heptadecane (HD) is a useful solid–liquid phase change material (PCM) because of its good thermal energy storage (TES) properties. However, leakage problems throughout the phase change and its relatively low thermal conductivity have significantly restricted its TES utility areas. Simultaneously, to prevent leakage and increase its thermal conductivity, HD was successfully encapsulated in a micro CaCO3 shell via a self-assembly mechanism. Fourier Transform Infrared (FTIR) analysis determined the chemical structures of the microcapsule's components. X-ray Powder Diffraction (XRD) results confirmed that the crystalline structures of both the HD core and CaCO3 shell were not impacted during the microencapsulation process. The SEM microstructures showed that the microcapsules had well-defined spherical morphology. Differential Scanning Calorimetry (DSC) measurements revealed that the HD within the capsule had a latent heat storage capacity in the range of 86–147 J/g when it melts and solidifies at around 16 °C. The 1000-times-cycled microcapsules demonstrated remarkable chemical stability and TES dependability. Thermogravimetry (TG) analysis showed that the microcapsules had excellent thermal degradation durability. All the produced microcapsules had greater thermal conductivity than the pure HD. The heat storage and releasing periods of the microcapsules were considerably reduced because of their enhanced thermal conductivity. The results revealed that the synthesised HD@CaCO3 microcapsules can be evaluated in different TES applications, such as the air conditioning of buildings, thermal management of textiles and thermal preservation of foods.

The development of iron and titanium carbides nanoparticles reinforcements during the mechanosynthesis Cu–10Sn–15Ti/diamonds composite powders from a mixture of blended Cu/Sn/Ti powders and synthetic diamonds (10 wt.%) was studied in this work. The analysis of the microstructure evolution showed that mechanical alloying performed at high-energy ball milling (600 rpm) allows developing different metastable phases depending on the SA content and milling time. For 3 wt.% of SA, XRD patterns revealed a metastable Cu(Sn) solid solution is produced after 5 h of MA while Fe2.939O4, FeTiO3 and TiH0.66 nanophases were formed for milling times higher than 15 h as a result of degradation of the SA in form of gaseous products (CO, CO2, H2, and lighter hydrocarbons (HC's)). XRD confirm that the release of these gases, along the SA degradation, and high carbon content carbon favors the carbothermic reduction of Fe2.939O4 for producing amorphous Fe3C nanoparticles at low-temperature thanks to the high-energy transferred in each impact during the MA process. For 1 wt.% of SA, XRD patterns showed the formation of Cu (Ti, Sn), from the very beginning of the process (5 h), is accompanied by the release of carboxyl groups ( COOH) and crystallization of long heptadecane chains, CH3(CH2)15CH3. The high boiling point of this heptadecane chains and the low Fe released during milling, produces a lower content of amorphous Fe3C nanoparticles. DSC and SAED patterns performed in the mixture of both alloyed powders after heating up to 1000 °C showed the carbothermic reduction of FeTiO3 for producing TiC nanoparticles takes place preferably when a 3 wt.% of SA is used. In both cases, the resulting alloyed powders are composed by a mixture of crystalline Cu13.7Sn + Fe + Fe3C + C + TiC phases with an Fe, and Fe3C and TiC content lower in the case of the powders processed with 1 wt.% SA. The development of this dissimilar Fe3C and TiC content produces the mixture with 3 wt.% of SA shows a higher stiffness.

This work reports physical property measurements of binary mixtures of butylbenzene with n-decane, n-dodecane, n-tetradecane, n-hexadecane, or n-heptadecane. Densities and viscosities were measured at temperatures from (293.15 to 373.15) K, and speeds of sound were measured at temperatures from (293.15 to 333.15) K, except for those of n-heptadecane, which were measured starting at 303.15 K. Densities increased with increasing mole fraction of butylbenzene. Excess molar volumes were positive and increased with increasing alkane chain length, except for those of heptadecane which were similar to those of n-hexadecane. Analysis of excess molar volumes using the Prigogine–Flory–Patterson model showed that the interaction term contributed more to excess molar volume than the free volume or P* term. As the mole fraction of butylbenzene increased, speeds of sound increased for n-decane and n-dodecane mixtures but decreased for other alkane mixtures to values below those of both pure components before increasing...

A series of SiO2-ZrO2 mixed oxide with varying SiO2 concentrations was hydrothermally synthesized and used as support for Ni in the hydrodeoxygenation of stearic acid. ZrO2 provides a relatively low surface area and only Lewis acid sites, and Ni supported on ZrO2 produces n-heptadecane from stearic acid via hydrogenation and decarbonylation. The SiO2-ZrO2 mixed oxides have a higher specific surface area as well as a novel spherical and nano-layer shaped morphology. Bronsted acid sites are created by incorporation of SiO2 into ZrO2 promoting the hydrodeoxygenation activity of Ni and specifically opening a new reaction route to n-octadecane via the dehydration of 1 octadecanol intermediate into 1-octadecene with subsequent hydrogenation.

BACKGROUND Carboxylic acids obtained from biomass raw materials are attractive starting chemicals in the conversion to linear, paraffinic hydrocarbons. The resultant hydrocarbon products can be used as platform chemicals for the production of fuels, lubricants and other valuable chemicals. RESULTS The effects of reaction parameters on the decarboxylation of oleic acid to paraffins, and hydrocarbons over Pt supported on zeolite 5A beads coated with ZIF-67 membrane (Pt/ZIF-67 membrane/zeolite 5A) were investigated. Almost complete conversion of oleic acid was observed for all reaction conditions studied here. The catalysts displayed high selectivity to heptadecane even with as low as 0.5 wt% Pt loading. Moderate reaction temperature and pressure were favorable to obtain high yield of heptadecane. The catalysts displayed a slight decrease in catalytic activity after recycling. Interestingly, of all explored reaction conditions, the catalysts exhibited the highest selectivity to heptadecane (~91%) in the presence of CO2. CONCLUSION The results from this work, demonstrate that the studied reaction parameters greatly affected the overall catalytic performance (mainly product distribution) for the decarboxylation of oleic acid into heptadecane over Pt/ZIF-67 membrane/zeolite 5A catalysts.

Recently, ruthenium-catalyzed isomerization–decarboxylation of fatty acids to give alkene mixtures was reported. When the substrate was oleic acid, the reaction yielded a mixture consisting of heptadecene isomers. In this work, we report the compositional analysis of the mixture obtained by triruthenium dodecacarbonyl catalyzed decarboxylation of oleic acid. Surprisingly, the most prominent single compound identified was heptadecane at approximately 18 wt %. A mixture of heptadecene isomers constituted the greatest percentage of the product (>75%), where all positional isomers were confirmed by GC–MS analysis of dimethyl disulfide derivatives of the product. Besides these components, minor amounts of alkyl aromatics, each with a total of 17 carbons atoms, among them undecyl benzene, were observed. Minor amounts of other compounds, such as shorter-chain hydrocarbons and polyunsaturated C17 compounds, were also observed. A reaction pathway to explain the existence of these products is proposed. Heptadecenes...

The catalytic deoxygenation of fatty acids has recently received significant attention as a low-hydrogen approach to biomass feedstock deoxygenation for production of hydrocarbon fuels with superior properties to biodiesel. Unfortunately, it is a challenging reaction to push to high yields. Of typical catalysts, Pd/C is typically reported to give the best performance, while most oxide supports are inferior, with exceptions for very specific preparation and pre-treatment protocols. Here, we investigate the role of organosilane-modified silicas as supports for the Pd-catalyzed deoxygenation of stearic acid at 300 °C under inert atmosphere. Comparing aminopropylsilane-modified, phenylsilane-modified, and unmodified silica supports with Pd incorporated by several methods, it is first shown that changes in dispersion alone do not account for improvements in deoxygenation yields. Capping silanols with phenylsilane is also ineffective on its own in improving deoxygenation yields. The most effective treatment is shown to be a co-deposition of phenylsilane and aminopropylsilane before Pd incipient wetness impregnation, followed by direct reduction of the catalyst, which gives heptadecane yields >85%, exceeding even the productivity of Pd/C. These results demonstrate that basic, aromatic-rich surfaces are accessible through organosilane grafting and that these surfaces can control Pd particle sizes and the adsorption of stearic acid and products. This work improves our understanding of support effects for biomass feedstock deoxygenation catalysts and could help design new catalysts that take advantage of modified inorganic supports.

Hydrocarbons are widespread in cyanobacteria, and the biochemical synthetic pathways were recently identified. Intracellular fatty alka(e)nes of cyanobacteria have been detected by liquid-liquid extraction (LLE) coupled to gas chromatography-mass spectrometry (GC/MS). However, whether fatty alka(e)nes can be released to cyanobacterial culture media remains to be clarified. This work develops a sensitive method for analyzing the trace level of extracellular hydrocarbons in cyanobacterial culture media by head space solid-phase microextraction (HS-SPME) coupled to GC/MS. Headspace (HS) extraction mode using polydimethylsiloxane fiber to extract for 30min at 50°C was employed as the optimal extraction conditions. Five cyanobacterial fatty alka(e)nes analogs including pentadecene (C15:1), pentadecane (C15:0), heptadecene (C17:1), heptadecane (C17:0), nonadecane (C19:0) were analyzed, and the data obtained from HS-SPME-GC/MS method were quantified using internal standard peak area comparisons. Limits of detection (LOD), limits of quantitation (LOQ), linear dynamic range, precisions (RSD) and recovery for the analysis of extracellular fatty alka(e)nes of cyanobacteria by HS-SPME-GC/MS were evaluated. The LODs limits of detection (S/N = 3) varied from 10 to 21 ng L-1. The correlation coefficients (r) of the calibration curves ranged from 0.9873 to 0.9977 with a linearity from 0.1 to 50 μg L-1. The RSD values were ranging from 7.8 to 14.0% and from 4.0 to 8.8% at 1.0 μg L-1 and 10.0 μg L-1 standard solutions, respectively. Comparative analysis of extracellular fatty alka(e)nes in the culture media of model cyanobacteria Synechocystis sp. PCC 6803 demonstrated that sensitivity of HS-SPME-GC/MS method was significantly higher than LLE method. Finally, we found that heptadecane can be released into the culture media of Synechocystis sp. PCC 6803 at the later growth period.