Homologous Series Of N-alkanes Research Articles

Correlation of properties in hydrocarbons homologous series

Correlations between combustible substances properties in the homologous series of n-alkanes and n-alcohols with a length of nС=1–20 were studied in order to determine ways to increase the methods convergence for assessing fire hazard parameters. The cluster length was added to the substance modulating parameters set. It should be noted that substances properties are often predicted using a molecule coarse-grained model, which has discreteness, does not describe short molecules, and requires an individual approach. It is shown that there are substance "arithmetic" parameters that directly depend on the certain atoms number. Among them, "length" better reflects isomeric, conformal, cluster differences, which are associated with parameters anomalies of hydrocarbons. A vaporization heat linear description from nС separately for n-alkanes and n-alcohols gives R=0,999. Exponential approximation of the n-alkanes boiling point tbp and flash point tfp by nС change fractions has R=0,999. It is shown that there is a correlation between tfp and tbp, but with a systematic difference, which indicates that the cluster composition is not completely similar at these temperatures; between tfp and tmp there is a smaller correlation, but its presence indicates clusters partial similarity. A universal formula for predicting hydrocarbons vaporization heats of 10 homologous series has been created, which has R=0,996. The description change hydrocarbons pulsations of in tmp was carried out on the cluster schemes alternation basis in homologous series, as well as taking into account their length and molar mass, which gives R=0,9997. According to similar principles, a formula for the hydrocarbons solubility in the water has been developed, which has the satisfactory accuracy. The study showed that the cluster length is a determining factor by which substance properties are modulated.

Turning Polyethylene Waste to Hydrocarbons Using a Sustainable Acidic Carbocatalyst.

Careless release of plastic waste is a pressing problem for marine and other eco-environments, and materials recycling of this stream is an open problem. For this purpose, a new metal-free acidic carbocatalyst with 8 wt % sulfur is constructed from a side product of the paper industry namely Na-lignosulfonate. The catalyst shows an extraordinary performance for the fragmentation of polymer waste which smoothly occurs above the ceiling temperature of the polymers. The reaction is run without hydrogen and at ambient pressure with commercially available high-density polyethylene (HDPE) as well as a real polymer waste mixture of high and low-density polyethylene (HDPE, LDPE). In all cases, a homologous series of n-alkanes and n-alkenes are obtained. The unique sulfur-rich carbonaceous structure (transfer hydrogenation functionality) and the metal-free character of the acidic carbocatalyst makes it inert against many typical catalyst poisons, among them water, salt, polar functionalities, and sulfur species. The described performance in plastic recycling, as well as the low cost and large-scale availability of lignosulfonate from the pulp industry, makes this metal-free acidic carbocatalyst promising for real-life environmental applications.

Homologous series of n-alkanes and fatty acids in the summer atmosphere from the Bering Sea to the western North Pacific

Lipid biomarkers can be used as key tracers for studying organic aerosols. To better understand the effects of anthropogenic and natural sources on Northern Hemisphere organic aerosols over the marine boundary in the context of global warming, we investigated n-alkanes and fatty acids in three years of summer aerosol samples which were collected from the Bering Sea (BS) to the western North Pacific (WNP) atmosphere during the cruise of China Arctic Research Expedition in 2014, 2016 and 2018. Lipid concentrations were the highest in 2018, with the WNP influenced by neighboring Eurasia and the BS influenced by the transport of aerosols from the WNP as well as an increased primary productivity. The sources of n-alkanes and fatty acids were found to be similar, and the qualitative assessment of the characteristic parameters indicated that temporally, n-alkanes were more abundant from higher plant wax in 2016 and 2018 as well as fatty acids in 2018. Furthermore, the quantitative assessment of principal component analysis with multiple linear regression showed that spatially, the WNP and BS were most influenced by terrestrial natural sources (57.8%) and anthropogenic sources (58.8%), respectively, and the contribution of marine emissions to BS was higher. In addition, the evaluation of organic carbon (OC) contribution revealed that lipids from BS contributed more OC and that the contribution of fatty acids to OC was higher than that of n-alkanes. This study provides useful information for further understanding the sources and influencing factors of organic aerosols.

Analysis of volatile compounds in flesh, peel and seed parts of pumpkin (Cucurbita maxima) cultivated in Ethiopia using gas chromatography-mass spectrometry (GC-MS)

ABSTRACT This study was aimed to analyze and compare the volatile compounds of flesh, peel and seed parts of the pumpkin (Cucurbita maxima). The volatile compounds were extracted from three different parts of pumpkin using a hydro-distillation method. Extracts from the three different parts of pumpkin were injected into the gas chromatography-mass spectrometry system. Mass spectral data were collected from 40–650 m/z. The volatile components were identified by matching their mass spectra with those of reference compounds recorded in the mass spectral library and retention indices. A homologous series of n-alkanes (C9–C30) were run under the same operating conditions as the volatile oils to determine the retention indices. The chromatographic analysis revealed the presence of 15, 23 and 28 components in the essential oils obtained from flesh, peel and seed parts of pumpkin representing a total composition of 81.5, 84.4, and 97.7%, respectively. Out of volatile compounds that were identified, three were common to all 3 parts, six were common to flesh and peel, eight were common to peel and seed, and five were common to flesh and seed. Hydrocarbons (43.6%) and esters (26.4%) were the most abundant volatile compounds identified in the seed part of pumpkin followed by sulfur containing compounds (30.3%) in the peel, (23.7%) in the flesh and (12.7%) in seed parts of pumpkin. Terpinene compounds were also found (23.5%) in the flesh, (22.9%) in the peel and (5.02%) in the seed parts of pumpkin. The compositions of the volatile compounds vary from one part to another of the pumpkin. Some of the volatile chemicals discovered in this investigation matched with the published data from other nations. According to the findings of this study, different volatile chemicals detected in various parts of the pumpkin indicated increased medicinal and nutritional potential.

ACEOS – The additive and constitutive equation of state in the n-alkane homologous series

The critical volumeVc, the relation between the critical temperature and the pressure Tc / Pc and the product PcVc2 depend linearly on the number of carbons in a homologous series as a consequence of the theory of corresponding states. This suggests that additive and constitutive properties are suitable for the construction of equations of state. In this article, an equation of state of Soave–Redlich–Kwong type is proposed: an additive and constitutive equation of state because it contains among its constitutive parameters the parachor (℘ch) and the molar refraction (Rm). The homologous series of the n-alkanes is used to illustrate the applicability of the proposed equation.

Adsorption and Chromatographic Characteristics of Graphitized Carbon Black, Modified by Adenine with Respect to a Series of Organic Compounds

Graphitized carbon black, modified by 0.95% adenine, is selected as the main object of study. The thermodynamic characteristics of adsorption of a series of organic compounds on modified carbon black is investigated by inverse gas chromatography. Analysis of the resulting data shows that the additivity of molar changes in the internal energy of adsorption is violated in the considered sample, in a homologous series of n-alkanes and other compounds. In contrast to a series of adsorbents studied earlier, there is no violation of additivity for pairs, but there is for at least three members of the homologous series, testifying to the presence of cavities or voids with different sizes in the supramolecular structure of adenine. The sizes of the molecules for which the violation of additivity is observed allow us to estimate the sizes of the cavities in the supramolecular structure of adenine as 5.5–6 to 9–9.5 A. It was also found that modification by adenine increases the polarity of the surface. The use of adenine at Viedma ripening conditions provides the modified adsorbent the chiral recognition capability.

Aerosol-associated non-polar organic compounds (NPOCs) at Jammu, India, in the North-Western Himalayan Region: seasonal variations in sources and processes.

Fine particulate (PM2.5) bound non-polar organic compounds (NPOCs) and associated diagnostic parameters were studied at Jammu, an urban location in the foothills of North-Western Himalayan Region. PM2.5 was collected daily (24h, once a week) over a year to assess monthly and seasonal variations in NPOC concentration and their source(s) activity. Samples were analyzed on thermal desorption-gas chromatography mass spectrometry to identify and quantify source-specific organic markers. Homologous series of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), isoprenoid hydrocarbons and nicotine were investigated to understand the sources of aerosols in the region. The annual mean concentration of PM2.5 during the sampling period was found higher than the permissible limit of India's National Ambient Air Quality Standards (NAAQS) and World Health Organisation (WHO) guidelines. The rise of concentration for PM2.5 and associated NPOCs in summer season was attributed to enhanced emission. The n-alkane-based diagnostic parameters indicated mixed contributions of NPOCs from anthropogenic sources like fossil fuel-related combustion with significant inputs from biogenic emission. Moreover, high influence of petrogenic contributionwas observed in summer (monsoon) months. The quantifiable amounts of isoprenoid hydrocarbons further confirmed this observation. Total PAH concentration also followed an increasing trend from March to June, and June onwards a sharp decrease was observed. The higher concentration of environmental tobacco smoke marker nicotine in winter months was plausibly due to lower air temperature and conditions unfavourable to photo-degradation. A clear dominance of low molecular weight PAHs was noticed with rare presence of toxic PAHs in the ambient atmosphere of Jammu. PAH-based diagnostic parameters suggested substantial contribution from low temperature pyrolysis processes like biomass/crop-residue burning, wood and coal fire in the region. Specific wood burning markers further confirmed this observation.

The effect of column and temperature variation on the determination of the dead time in gas chromatographic systems using indirect methods

The precise determination of the dead time is essential in a chromatography system as it is a primary parameter for the determination of other secondary parameters such as the adjusted retention time, relative retention time, retention factor and retention index. Several of the indirect methods used for the determination of the dead time in this study were iteration, nonlinear, spreadsheet and statistics methods, which were implemented using the ANSI C programming language. The calculation of each method was tested with temperature and column variations for measuring the retention time of a n-alkane homologous series and accuracy analysis of each mathematical method (indirect method) to the marker substance (direct method). Changes in the temperature and column variations (type, polarity and column length) affected the calculation of the dead time values but did not affect its accuracy. The value of the dead time generated by the non-linear method was relatively high, with errors above 10%, while the other methods utilized are quite good with errors below 8% regardless of the column and temperature variations.

Analysis of temperature and column variation in gas chromatography to dead time of inert gas and n-alkane homologous series using randomized block design

The dead time behavior from several inert gas and mathematical methods under temperature and column variation have been studied using randomized block design. Dead time of inert gas and mathematical dead time calculated using n-alkane homologous series that measurement with gas chromatography at temperatures of 60, 90 and 120°C and columns of PS-255, OV-11, CPSIL-5CB, HP -5 and HP-INNOWAX were used as a set data in randomized block design. The results showed that temperature variation affects all dead time values, either for inert gas dead time or mathematical method, except for Parcher method. Different column types between capillary and packed column exhibits a significant effect. For capillary column, all dead time values, either for inert gas dead time or mathematical method is not affected by polarity variation, but they are affected by the column length. Meanwhile for packed column, column length does not affect the mathematical dead time of Ne and He gases, but it affects the dead time of O2 and Ar gases. Parcher method exhibits the best result with a robust dead time, without significant effect in statistics by the change of temperature and column.

Investigation on the adsorption mechanism and model of didodecyldimethylammonium bromide on ZnO nanoparticles at the oil/water interface

We systemically evaluated the effects of the additional ZnO nanoparticles (NPs) on the interfacial activity of the cationic surfactant didodecyldimethylammonium bromide (DDAB) with two hydrophobic chains by the interfacial tension (IFT) measurement and emulsification experiments. The addition of ZnO NPs greatly improved the interfacial activity of the mixed ZnO/DDAB system at the oil/water interface. The zeta potential and fluorescence spectra of the mixed ZnO/DDAB dispersions were investigated to explore the adsorption behavior of DDAB molecules on ZnO NP surfaces. The IFT between a homologous series of n-alkanes and DDAB aqueous solutions in the absence and presence of ZnO NPs was measured to explore the mechanism of the further IFT reduction caused by the additional ZnO NPs. The dynamic IFT data were fitted with two different models. The results indicated that the DDAB adsorption processes in the absence and presence of ZnO NPs were controlled by the mixed diffusion-kinetic controlled model.

Study of pyrolysis behavior of hydrogen-rich bark coal by TGA and Py-GC/MS

Hydrogen-rich bark coal has anomalous thermal behaviors compared to humic coals, with high fluidities (>180,000 ddpm (dial divisions per minute)) and intense thermal reaction (the highest mass loss rate is 1.11%/°C). However, the reason causing its different behavior is not fully understood. The pyrolysis behaviors of bark coal and barkinite were investigated by thermogravimetric analysis (TGA) and pyrolysis gas chromatography and mass spectroscopy (Py-GC/MS). The aromatic structural characteristics of bark coal and barkinite were studied by gas chromatography and mass spectroscopy (GC/MS) techniques. The Py-GC/MS results showed that the pyrolysates of bark coal and barkinite are similar, which are mainly characterized by the presence of alkylbenzenes, alkylnaphthalenes, alkylphenols, phenanthrene, and homologous series of n-alkanes and n-alk-1-enes. The aromatic fraction of both bark coal and barkinite are mainly composed of tricyclic compounds (phenanthrene) while vitrinite in bark coal is bicyclic compounds (naphthalene) and tricyclic compounds (phenanthrene), as indicated from GC/MS results. Barkinite has an intensive thermal decomposition. The shapes of the DTG curve of barkinite at different heating rates were symmetrical. With the increase in heating rates, the peaks shifted to higher temperatures, the temperatures of maximum weight loss increase, and the values of the maximum rate of weight loss decrease. Comparing to vitrinite in bark coal, barkinite has higher values both the maximum rate of weight loss and the weight loss. The similarity in pyrolysis behavior, Py-GC/MS, and GC/MS for bark coal and barkinite suggested that barkinite is the main factor that causes the abnormal thermal pyrolysis of hydrogen-rich bark coal.

Adsorption of organic molecules on the highly ordered MCM-41 sorbent modified by different amounts of melamine

Thermodynamic characteristics of adsorption of organic molecules on the ordered organosilylated composite MCM-41 with grafted trimethylsilyl groups (MMet) and modified by melamine deposited on the surface were studied by inverse gas chromatography. Mole changes in the internal energy and entropy of adsorption, the dispersion and specific components of the value proportional to the Helmholtz absorption energy, and the contribution of the methyl group to the heat of adsorption were calculated from the specific retention volumes. The change in the retention volumes was established to be determined by the dispersion component of the Helmholtz energy of adsorption, whereas the energy of specific interactions remains almost unchanged. After the adsorbent surface was coated by the second and third melamine layers, the changes in −ΔU and −ΔS for adsorption of the members of the homologous series of n-alkanes are so small that lie within admissible measurement inaccuracies. This phenomenon can be explained by the regularities of alkane adsorption in slit-like pores of the supramolecular structure of melamine.

The Zigzag Progression of Melting and Triple Point Properties of <i>n</i>-Alkanes, <i>n</i>-Alcohols, <i>n</i>-Alkanoic Amines and <i>n</i>-Alkanoic Acids

In the paper, we discuss the phenomenon of melting and triple point properties deviations from regularity in tangent of slope and “zigzag” progression in n-alkanes, n-alcohols, n-alkanoic amines and n-alkanoic acids. The thermodynamics and chemical aspects of this intriguing phenomenon will be discussed. In graphs of melting and triple point properties of saturated alkanoic (fatty) acids, n-alcohols, n-amines and n-alkanes homologous series have been observed two segments, which are characterized by changes in tangent of slope from the fifth member of homologous series, and harmonic zigzag progression of melting and triple point temperatures and some other thermophysical parameters. The melting and triple point temperatures for even numbers of carbon atoms in homologous series of n-alkanes, n-alkanoic acids, n-alcohols, n-amines and some cyclic and polycyclic substances are larger than average values of the nearest odd numbers. A general character of this phenomenon for a wide number of substances motivates researchers to study the nature and mechanism of it and its implication.

Size distributions of n-alkanes, fatty acids and fatty alcohols in springtime aerosols from New Delhi, India

Size-segregated aerosol samples were collected in New Delhi, India from March 6 to April 6, 2012. Homologous series of n-alkanes (C19C33), n-fatty acids (C12C30) and n-alcohols (C16C32) were measured using gas chromatography/mass spectrometry. Results showed a high-variation in the concentrations and size distributions of these chemicals during non-haze, haze, and dust storm days. In general, n-alkanes, n-fatty acids and n-alcohols presented a bimodal distribution, peaking at 0.7–1.1 μm and 4.7–5.8 μm for fine modes and coarse modes, respectively. Overall, the particulate matter mainly existed in the coarse mode (≥2.1 μm), accounting for 64.8–68.5% of total aerosol mass. During the haze period, large-scale biomass burning emitted substantial fine hydrophilic smoke particles into the atmosphere, which leads to relatively larger GMDs (geometric mean diameter) of n-alkanes in the fine mode than those during the dust storms and non-haze periods. Additionally, the springtime dust storms transported a large quantity of coarse particles from surrounding or local areas into the atmosphere, enhancing organic aerosol concentration and inducing a remarkable size shift towards the coarse mode, which are consistent with the larger GMDs of most organic compounds especially in total and coarse modes. Our results suggest that fossil fuel combustion (e.g., vehicular and industrial exhaust), biomass burning, residential cooking, and microbial activities could be the major sources of lipid compounds in the urban atmosphere in New Delhi.

The hydropyrolysis (HyPy) release of hydrocarbon products from a high maturity kerogen associated with an orogenic Au deposit and their relationship to the mineral matrix

An innovative experimental approach has been applied to a metamorphosed (>550°C) kerogen associated with orogenic Au mineralisation. The novel application of catalytic Hydropyrolysis (HyPy) to mineralised sediments associated with Au-mineralisation successfully liberated GC–MS-detectable hydrocarbons interpreted as indigenous to the high maturity organic matter (OM), and previously proven unamenable to more traditional methods of organic geochemical analyses. These organic compounds were likely sequestered within condensed polyaromatic structures of the high maturity kerogen that exhibited an intimate relationship to the mineral matrix as documented using high resolution in-situ microscopy. The major pyrolysis products were the polycyclic aromatic hydrocarbons (PAHs) pyrene (detected in particularly high abundance), coronene and hydrogenated analogues of these 4- and 7-ringed systems. To help distinguish the importance of specific organic–mineral relationships, each sample was subjected to a sequential demineralisation process using three increasingly stronger acids (i.e. 3M HCl, 12M HCl, HF). The kerogen isolated following each demineralisation step was subject to HyPy and then GC–MS analysis. Pyrene and hydrogenated analogues were again the major HyPy products of all demineralised kerogens (similar to the parent kerogen result). Other 2–7 ringed hydrocarbons and a homologous series of n-alkanes also were detected. Subtle differences in the distributions of compounds released and a pronounced increase in the abundance of most HyPy products at each demineralisation step (TOC also showed a general increase) were observed. These observations could be attributed to the increasing release of mineral-bound hydrocarbons, indicating the strong organic affinity for a wide variety of mineral types. The intimate association of the kerogen and minerals was clearly evident in the SEM–EDS photomicrographs of several freshly fractured surfaces that showed OM along mineral boundaries as inclusions, and as continuous infill in mineral grains. Most of the OM is intricately embedded in the clay structures. These mineral–kerogen relationships are retained even when the samples were finely powdered. Laser Raman analysis identified highly ordered and aromatic graphitic like carbonaceous material (CM-1) associated with the sedimentary matrix, although a distinct type of less ordered CM (CM-2) was also identified in proximity to sulphide veins — reflecting a separate organic origin of preservation pathway. The sequestration and protection of these hydrocarbons from thermal destruction likely result from an intimate structural relationship between the minerals and OM. This pioneering analytical approach represents a major breakthrough to the organic characterisation of sediments metamorphosed by high temperature mineralisation processes.

Chemical Composition of Eremostachys labiosiformis Growing Wild in Iran and Antimicrobial Activities Against Phytopathogenic Bacteria

Eremostachys labiosiformis (Popov) Knorring is a species of flowering plants in the Labiatae family known by the common name, Sonboleh Biabani in Iran. These species are native to Iran, Turkmenistan, and Afghanistan. It is a perennial herb with tuberculate fibrous root, lunate at base. The stem is 40–60 cm, often simple, with simple and fascicled hairs. The leaves are petiole, with basal leaves shorter than the limb, limb 8–20 5–8 cm, oblong or oval, stem leaves shortly petiolate, lower surface with stellate or simple and glandular hair. The flowers are large, yellow, verticillasters 5–7, lower distant, multiflowered, corolla 30–35 mm, upper lip 15 mm, lower lip longer than the upper lip, with hairy annulus within. The flowering period is May–June [1]. Plants produce a diverse range of bioactive molecules, making them, a rich source of different types of medicines. Approximately 20% of the plants found in the world have been submitted to pharmaceutical or biological test, and a sustainable number of new antibiotics introduced on the market are obtained from natural or semisynthetic resources [2]. It has been reported that between the years 1983 and 1994 the systematic screening of antibacterial plant extracts represents a continuous effort to find new compounds with the potential to act against multi-resistant bacteria [3]. So far, no research on phytochemical studies on this plant has been reported. The aim of our study was to evaluate the chemical composition and antimicrobial activity of E. labiosiformis. E. labiosiformis were collected at the flowering stage from the area of Bojnourd, Iran, in June 2011 and identified at the Research Center for Plant Sciences, Ferdowsi University of Mashhad, Iran. A voucher specimen has been deposited in the Environmental Department of Bojnourd Herbarium (EDBH:00108). The present study carried out on E. labiosiformis revealed the presence of medicinal active constituents. The phytochemical active compounds were qualitatively analyzed, and the results are presented in Table 1. In this screening process, alkaloid, saponin, flavonoids, and tannin gave positive results. Gas chromatographic analysis was performed on a Hewlett–Packard (HP) 6890 A instrument equipped with a flame ionization detector and Rtx-5MS (15 m 0.25 mm 0.25 m) capillary column, while the essential oil components were identified on an Agilent Technologies 5973 N mass spectrometer. The GC settings were as follows: initial oven temperature held at 35 C for 6 min and ramped at 5 C min–1 to 150 C for 0 min, then ramped at 10 C min–1 to 280 C for 3 min. The injector temperature was maintained at 250 C. The samples (1 L) were injected neat, with a split ratio of 1:10. The carrier gas was helium at a flow rate of 1.0 mL min–1. Spectra were scanned from 20 to 550 m/z at 2 scans s–1. Most constituents were identified by gas chromatography by comparison of their retention indices with those of the literature or with those of authentic compounds available in our laboratories. The retention indices were determined relative to a homologous series of n-alkanes under the same operating conditions. Further identification was made by comparison of their mass spectra on both columns with those stored in the NIST 05 and Wiley 275 libraries or with mass spectra from the literature [4, 5]. Component relative percentages were calculated based on GC peak areas without using correction factors. The average yield of chemical components of E. labiosiformis was 0.55%. The chemical composition of the plant is outlined in Table 1. Twenty-eight components were identified, accounting for 83.4% of the total oil. The various compounds were identified by comparison of their Kovats retention indexes, determined utilizing a nonlogarithmic scale on nonpolar (Rtx-5MS) columns, and by comparison of the mass spectra of each GC component with those of standards and with reported data [4].

Female-Released Sex Pheromones Mediating Courtship Behavior inLysiphlebus testaceipesMales

Ethological aspects and chemical communication at close-range between the sexes of Lysiphlebus testaceipes Cresson (Hymenoptera: Braconidae) have been investigated through behavioral bioassays and chemical analysis. The attractiveness toward males of whole-body extracts of females and males in hexane and acetone was evaluated, adopting male fanning behavior as a key behavioral component. Also, the activity of polar and nonpolar fraction of female-body extract in hexane obtained using solid-phase extraction technique was investigated. In order to identify cuticular compounds, male and female whole-body extracts with hexane and acetone were analyzed by gas chromatography-mass spectrometry. The results showed that males exhibit a behavior including 4 phases when exposed to virgin females: premount, mount, copulation, and post-copulation. A preliminary courtship of the male included wing fanning, an extension and vibration of the wings for 1 to 2 seconds. Also, some original aspects not described for other species were carried out. The average duration of the entire sequence of events was 138.80 ± 19.51 sec. Also, males displayed significantly more wing fanning behavior in response to female whole-body hexane extracts (70.83%) than female whole-body acetone extracts (33.3%). Furthermore, males did not respond to male-body extracts or to the control (pure hexane and acetone), suggesting that the sex pheromone is composed of cuticular hydrocarbons that are also involved in the male courtship behavior. When hexane extracts of whole females were fractionated on silica gel and exposed to males, more activity was recorded for the nonpolar fraction (50.0%) than the polar fraction (27.7%), but no significant statistical difference was found. Significant differences were detected comparing the control (not fractionated extract) with the polar fraction, but not with the nonpolar fraction. A homologous series of n-alkanes with chain lengths from C19 to C30 carbon atoms was identified and quantified in the solvent extracts of wasp males and females. Between male and female extracts, there was a statistically significant difference in the average quantity of some of these hydrocarbons, such as C27, C28, and C29.

Solid waste deposits as a significant source of contaminants of emerging concern to the aquatic and terrestrial environments — A developing country case study from Owerri, Nigeria

In developing countries, there are needs for scientific basis to sensitize communities on the problems arising from improper solid waste deposition and the acute and long-term consequences for areas receiving immobilized pollutants. In Nigeria, as in many other African countries, solid waste disposal by way of open dumping has been the only management option for such wastes. Herein, we have highlighted the challenges of solid waste deposit and management in developing countries, focusing on contaminants of emerging concern and leaching into the environment. We have analyzed sediments and run-off water samples from a solid waste dumping site in Owerri, Nigeria for organic load and compared these with data from representative world cities. Learning from previous incidents, we intend to introduce some perspective for awareness of contaminants of emerging concerns such as those with potential endocrine disrupting activities in wildlife and humans. Qualitative and quantitative data obtained by gas chromatography and mass spectrometric analysis (GC–MS) provide an overview on lipophilic and semi-polar substances released from solid waste, accumulated in sediments and transported via leachates. The chromatograms of the full scan analyses of the sediment extracts clearly point to contamination related to heavy oil. The homologous series of n-alkanes with chain lengths ranging between C16 and C30, as well as detected polyaromatic hydrocarbon (PAH) compounds such as anthracene, phenanthrene, fluoranthene and pyrene support the assumption that diesel fuel or high boiling fractions of oil are deposited on the site. Targeted quantitative analysis for selected compounds showed high concentration of substances typically released from man-made products such as plastics, textiles, household and consumer products. Phthalate, an integral component of plastic products, was the dominant compound group in all sediment samples and run-off water samples. Technical nonylphenols (mixture of isomers), metabolites of non-ionic surfactants (nonylphenol-polyethoxylates), UV-filter compound ethyl methoxy cinnamate (EHMC) and bisphenol A (BPA) were particularly determined in the sediment samples at high μg/kg dry weight concentration. Measuring contaminants in such areas will help in increasing governmental, societal and industrial awareness on the extent and seriousness of the contamination both at waste disposal sites and surrounding terrestrial and aquatic environments.

Surface energetics of bone mineral and synthetic hydroxyapatite using inverse gas chromatography

Surface energy is one of the important factors that govern protein adhesion and cell attachment on biomaterial surfaces. Inverse gas chromatography (IGC) provides an excellent method to measure the surface energetics of rough and porous biosurfaces. In this study IGC was used to characterize and compare the surface energetics of synthetic and biological hydroxyapatites (natural bone mineral). IGC experiments were performed on three samples: synthetic hydroxyapatites with two levels of purity (99% and 90%) and natural biological hydroxyapatite obtained from bovine trabecular bone. The Lifshitz–Van der Waals component of the surface free energy ( γ S L W ) and specific interaction parameter ( ɛ π) were determined by using homologous series of n-alkanes and alkenes as IGC probe molecules, respectively. The synthetic hydroxyapatite had values of γ S L W of 33.4 mJ m −2 at 99% purity and 53.3 mJ m −2 at 90% purity. Biological hydroxyapatite had a value of γ S L W of 45.7 mJ m −2. For the synthetic hydroxyapatite, the values of π-bond specific interaction parameters, ɛ π, were 0.95 mJ (99%) and 3.01 mJ (90%). The biological hydroxyapatite sample had a value of 2.44 mJ for ɛ π. The results suggest that, as compared to the synthetic compounds, the biological apatite has considerable surface heterogeneity, either chemical (impurities) or structural suggesting a scaffold surface that is more conducive of protein adhesion and cell attachment.

Single carbon surface reactions of 1-octadecene and 2,3,6-trimethylphenol on activated carbon: Implications for methane formation in sediments

The reactions of a terminal alkene (1-octadecene) and a polymethyl phenol (2,3,6-trimethylphenol) on activated carbon have been investigated in closed system pyrolysis experiments in the temperature range 170–340 °C. The reaction products of 1-octadecene included methane, isomeric octadecenes, methyl substituted alkanes, alkyl aromatics and an homologous series of n-alkanes with carbon numbers indicative of progressive single carbon depletion of the reactant. The reaction products of 2,3,6-trimethylphenol also contained methane, as well as C 1–C 4 methyl phenols produced by demethylation and methyl transfer reactions. A carbon surface reaction involving the formation of a reactive single carbon intermediate (i.e. methylene/carbene) is proposed. This reaction accounts for the products observed from the pyrolysis experiments and also is consistent with liquid hydrocarbon distributions found in petroleum basins. Methane was the dominant (ca. 85% of C 1–C 4) gaseous hydrocarbon product of 2,3,6-trimethylphenol but accounted for only ca. 17% of the C 1–C 4 hydrocarbons from 1-octadecene. These findings suggest that single carbon surface reactions may play an important role in the geochemical formation of crude oil and natural gas and that the composition of the source material and therefore the type of organic compounds undergoing such reactions, influences the hydrocarbon gas composition in sedimentary basins.