Nonpolar Organic Compounds Research Articles

Chemical Activity of Nascent Surfaces for Tribochemical Reactions of Lubricant Components.

Boundary lubrication characteristics are strongly dependent on tribochemical reactions at the contact interface. There are multiple factors that contribute to the activity of tribochemical reactions and the complexity of this phenomenon. Here, we focused on nascent surfaces created by friction and aimed to clarify their chemical properties. To achieve this, we first developed a method based on a mass spectrometer that can sensitively detect molecular adsorption and reactions on a nascent surface. We used various organic compounds as adsorbates and friction materials such as steel, aluminum, gold, and ceramics and examined adsorption of the organic compounds on the nascent surfaces. The adsorption properties of the additives differed between steel metal oxide and nascent steel surfaces. For example, polar organic phosphates, which are extreme-pressure additives, were more easily adsorbed on oxide surfaces, whereas nonpolar organic sulfur compounds were more easily adsorbed on nascent steel surfaces. Alcohols and ethers also adsorbed on nascent aluminum surfaces, whereas olefins and benzene did not. Nascent gold surfaces showed high catalytic activity. Saturated hydrocarbons and fluorinated compounds, which are chemically inert, were also adsorbed on nascent ceramic surfaces, showing high activity. Hydrocarbon oils decomposed through the influence of frictional heat on a nascent steel surface to generate hydrogen and methane. We applied reactive molecular dynamics to simulate the adsorption phenomenon on iron surfaces. As a result, the adsorption energy obtained by simulation and the experimentally determined adsorption activity correlated well. Thus, adsorption and reaction behaviors on nascent surfaces inferred by our method were theoretically supported. On the basis of the chemical properties of the nascent surfaces obtained here, it is possible to explain boundary lubrication phenomena.

Chemical characterization, source identification and potential health effects of PM2.5-bound non-polar organic compounds over a COALESCE network site - Bhopal, India

Year-long (2019) measurements of carbonaceous aerosols were performed at Bhopal, a regionally representative site as a part of the COALESCE (Carbonaceous Aerosol Emissions, Source apportionment and Climate Impacts) campaign. Aerosol-associated non-polar organic compounds (NPOCs) were analysed using thermal desorption (TD) Gas chromatography/Mass spectrometry (TD-GC/MS). The annual average of the total organic carbon (OC), elemental carbon (EC), and analysed PAHs (Polycyclic Aromatic Hydrocarbons), and n-alkanes were, 9.74 ± 9.47 μg m−3, 2.13 ± 3.12 μg m−3, 10.43 ± 5.49 ng m−3, and 114.93 ± 49.24 ng m−3, respectively. PAHs diagnostic ratios suggested emissions from petroleum, grass, wood, and coal combustion. Combustion derived PAHs (CombPAHs) accounted for 72.5 % of the total measured PAHs. During wintertime, based on Pyr/BaP ratio (∼0.6), gasoline exhaust emissions were higher compared to diesel exhaust emissions. The weak correlations between PAHs and meteorological parameters suggested that variations in PAH levels are primarily driven by alterations in emission sources. Total PAHs were correlated moderately with BrC (r2 = 0.60). The estimated lifetime lung cancer risk (LLCR) values on exposure to 16 USEPA priority PAHs (5 × 10−5) demonstrated that PAH levels in this region pose moderate health risks. Given observations from only campaign mode short-term measurements of NPOCs over India, this work provides a more comprehensive understanding of the concentrations, seasonal variations, and sources of n-alkanes and health risk associated with particle bound PAHs over the data-poor central Indian region.

Sources and influences of atmospheric nonpolar organic compounds in Nanchang, central China: Full-year monitoring with a focus on winter pollution episodes

Nonpolar organic compounds (NPOCs) are found in atmospheric aerosols and have significant implications for environmental and human health. Although many studies have quantitatively estimated the sources of NPOCs in different cities, few have evaluated their main influencing factors (e.g., emissions and meteorological conditions) at relatively long (e.g., different seasons) and short timescales (e.g., several days during pollution episodes). A better understanding of this issue could optimise strategies for dealing with organic contamination in atmospheric particulate matter. NPOCs (including n-alkanes, PAHs and hopanes) in fine particulate matter (PM2.5) were sampled daily at Nanchang, China, from 1 November 2020 to 31 October 2021. Analyses of specific biomarkers and diagnostic ratios indicate that the NPOCs mainly had anthropogenic sources. The quantitative estimates of a positive matrix factorization model show that fossil fuel and biomass combustion were the main sources of n-alkanes (contributing 64.8 %), while vehicle exhaust was the main source of PAHs (47.0 %) and hopanes (52.3 %). Seasonally, the contributions from coal and/or biomass combustion were higher in autumn and winter (40.2–56.3 %) than in spring and summer (25.7–44.3 %), while contributions from natural plants, petroleum volatilization and vehicle exhaust were higher in spring and summer (14.7–63.5 %) than in autumn and winter (8.1–48.9 %). Redundancy analysis shows that increased emissions, especially from coal and/or biomass combustion, are the main cause of increases in NPOCs, during both annual sampling periods and winter pollution episodes. Over the year, higher temperature and longer sunshine hours correspond to lower NPOC concentrations. In winter pollution episodes, increases in temperature and relative humidity correspond to increases in NPOC concentrations. Our results suggest that controlling primary emissions, especially from coal and biomass combustion, may be an effective way to prevent increases in NPOC concentrations.

Determining the fatty acids, polar and non-polar volatile organic compounds of the veterinary preparation “Trametin Plus”

For the prevention and treatment of associated gastrointestinal and respiratory diseases of growing stock, a new veterinary preparation “Trametin Plus” is proposed. This drug is obtained from fungi-xylotrophs using biotechnology methods. The properties of such preparations depend on bioactive substances included in their composition.Available publications present miscellaneous information on the lipogenesis features and fatty acids composition synthesized by wood-destroying fungi. In this work, we study the qualitative and quantitative composition of fatty acids and analyze volatile polar and non-polar organic compounds of “Trametin Plus”. The total concentration of fatty acids was found to be 70 µg/g, with 50.0% being free acids and 50.0% being their esters. Squalene was established to be the most dominant non-polar volatile component. Concerning the minor non-polar volatile components of “Trametin Plus”, these are amino acids with a low molecular weight, such as glycine, arginine and β-alanine. The analysis confirms the multicomponent composition of the preparation, which accounts for its diverse biological properties, namely antibacterial, antiviral, antioxidant and immune-boosting activity. These properties determine the high health-promoting efficacy of the studied veterinary preparation.

Investigation Of the Composition of The Veterinary Preparation Trametin Plus

For the prevention and treatment of associated gastrointestinal and respiratory diseases in young farm animals, a new veterinary drug Trametin Plus is proposed, obtained on the basis of xylographic fungi using biotechnology methods. The properties of biological products obtained on the basis of microorganisms and fungi depend on the biologically active substances that make up their composition. In the literature, there is scattered information about the features of lipogenesis and the composition of fatty acids synthesized by wood-destroying fungi. The paper presents data on the study of the qualitative and quantitative composition of fatty acids, a qualitative analysis of volatile polar and non-polar organic compounds of the drug. It has been established that the total concentration of fatty acids is 70 µg/g of the preparation. Of these, 50.0% are free fatty acids, the esterified acids of which account for 50.0% of the total mass of fatty acids. Among the dominant non-polar volatile components of Trametin Plus, squalene can be noted. Organic aliphatic amino acids such as glycine, arginine, and β-alanine with a small molecular weight are presented as minor non-polar volatile components of Trametin plus. The analysis data confirm the multicomponent nature of the drug, which determines its various biological properties, namely, antibacterial, antiviral, antioxidant and immunostimulant activity, which determines the high therapeutic and prophylactic efficacy of the veterinary drug Trametin Plus.

Study of metal and organic contaminants transported by microplastics in the Lebanese coastal environment using ICP MS, GC-MS, and LC-MS

An untargeted study of multiclass contaminants associated with microplastics (MPs) in the East Mediterranean was carried out. Samples were collected in 2020–2021 from the shoreline at 14 different locations, along the Lebanese coast. Attenuated Total Reflectance (ATR) FTIR spectroscopy showed the predominant presence of polyethylene and polypropylene among plastic debris. The non-polar and polar organic compounds sorbed on the MPs were identified and quantified by GC - TOF MS and LC – electrospray MS/MS, respectively. Deconvolution of accurate GC–MS scan data allowed the identification of >130 organic pollutants, 64 of which could be confirmed by matching with the authentic standards, among which a number of previously unreported in targeted GC–MS(MS) methods. In addition to highly toxic, legacy chlorinated pollutants, high levels (average values from 0.8 to 4.0 μg g−1) of some musks, UV filters and UV absorbers were detected. Untargeted LC-MS demonstrated the persistence of several pesticides (i.e., chlorpyrifos) and pharmaceuticals, such as phenacetin and minoxidil, which were quantified. In addition, a study of metals associated with microplastics using ICP-MS confirmed the high potential of microplastics to act as a vector of, among others, toxic metals, such as Cd, Pb, Bi or Hg.

Composition Characteristics and Sources of Non-polar Organic Compounds in PM2.5 in the Background Atmosphere of Yangtze River Delta

In order to explore the composition and source characteristics of non-polar organic compounds (NPOCs) in atmospheric fine particulate matter in the Yangtze River Delta region, 129 PM2.5 samples were collected at the Regional Atmospheric background station in Lin'an from December 2019 to November 2020. Including polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and hopanes, the main sources of organic aerosols were investigated using molecular tracers, eigen ratios, and orthogonal matrix factorization models. The results showed that the average annual mass concentration of PM2.5 in Lin'an was approximately (32.36±20.44) μg·m-3, and the average annual mass concentration of NPOCs was approximately (59.05±40.39) ng·m-3, showing the seasonal characteristics of being high in winter and low in summer. n-alkanes mainly came from fossil fuels and biomass (grass, wood, etc.) burning, followed by cuticle wax emission from higher plants. PAHs mainly came from the mixed contribution of non-fossil sources such as coal burning motor vehicle emissions and biomass combustion. Hopanes were mainly derived from motor vehicle emissions, which were also affected by coal burning in winter. Backward trajectory cluster analysis and potential source analysis showed that Lin'an was mainly affected by external air mass transport. Combined with the orthogonal matrix-factor decomposition model, NPOCs observed during the sampling period were analyzed, and non-fossil sources such as coal burning sources, transportation emission sources, and biomass combustion were obtained. In winter, transportation sources were the main source, accounting for 59%. In spring and summer, coal burning was the main source, accounting for 58% and 57%, respectively. In autumn, biomass combustion and other non-fossil sources dominated, accounting for 64%.

PM2.5-bound Inorganic and Nonpolar Organic Compounds in Chuncheon, Korea

In this study, major chemical components of PM2.5 including nitrate, sulfate, organic carbon (OC), and elemental carbon (EC) were measured in Chuncheon, South Korea in May–June, 2021. Average PM2.5 concentration was 16.4±9.7 µg m−3, and OC was the largest contributor of PM2.5 mass concentration. High concentration episodes (HCEs), defined when PM2.5 concentration exceeded 30 µg m−3, were caused by Asian dust, secondary inorganic aerosol (SIA) formation, and primary OC emission. NH4+ was determined to be a limiting factor for SIA formation based on neutralization ratio. There was statistically significant correlation between n-alkanes and PM2.5, and odd alkanes including C27, C29, and C31, which are generally emitted from biogenic sources, were abundant species, suggesting the importance of natural sources over fossil fuel combustion. Polycyclic aromatic hydrocarbons (PAHs) concentrations were significantly lower than those measured at the same sampling site in 2014–2015. Based on the diagnostic ratios of PAHs, vehicular emission, rather than solid fuel emission, were significant for PAHs. Detailed characterization of chemical composition of PM2.5 reported in this study can be of great help in establishing an appropriate abatement policy to reduce PM2.5 concentrations.

Understanding the in silico aspects of bacterial catabolic cascade for styrene degradation.

Styrene is a nonpolar organic compound used in very high volume for the industrial scale production of commercially important polymers such as polystyrene resins as well as copolymers like acrylonitrile butadiene styrene, latex, and rubber. These resins are widely used in the manufacturing of various products including single-use plastics such as disposable cups and containers, protective packaging, heat insulation, and so forth. The large-scale utilization leads to the over-accumulation of styrene waste in the environment causing deleterious health risks including cancer, neurological impairment, dysbiosis of central nervous system, and respiratory problems. To eliminate the accumulating waste. Microbial enzyme-based system represents the most environmental friendly and sustainable approach for elimination of styrene waste. However, comprehensive understanding of the enzyme-substrate interaction and associated pathways would be crucial for developing large-scale disposal systems. This study aims to understand the molecular interaction between the protein-ligand complexes of the styrene catabolic reactions by bacterial enzymes of sty operon. Molecular docking analysis for catalytic enzymes namely, styrene monooxygenase (SMO), styrene oxide isomerase (SOI), and phenylacetaldehyde dehydrogenase (PAD) of the bacterial sty operon was carried out with their individual substrates, that is, styrene, styrene oxide, and phenylacetic acid, respectively. The binding energy, amino acids forming binding cavity, and binding interactions between the protein-ligand binding sites were calculated for each case. The obtained binding energies showed a stable association of these complexes indicating the future scope of their utilization for large-scale bioremediation of styrene, and its commercially used polymers and copolymers.

Analytical procedure for the concomitant analysis of 242 polar and non-polar organic compounds of different functional groups in fog water

Fog droplets consist of a mixture of organic and inorganic compounds resulting from scavenging hygroscopic particles and water-soluble trace gases. Organic matters found in fog water are able to accumulate non-volatile, semi-volatile and volatile compounds of different chemical structures and properties (different functional groups and chemical properties). However, their extraction and analysis are still very limited and infrequent. The paper presents a new analytical procedure based on the combination of liquid–liquid extraction (LLE) on a solid support (XTR Chromabond cartridge). It is developed, optimized and validated for the simultaneous analysis of 38 organic acids, 64 phenols, 55 semi-volatile pesticides, 27 non-volatile pesticides, 16 polycyclic aromatic hydrocarbons (PAHs), 20 organochlorine pesticides (OCPs) and 22 polychlorinated biphenyls (PCBs) residues in fog water. The obtained extract is concentrated, derivatized and then analyzed with different chromatographic techniques. Phenols and acids are injected into gas chromatography-mass spectrometry (GC-MS) preceded by a derivatization reaction with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MtBSTFA). Semi-volatile pesticides, PAHs, PCBs and OCPs are injected into gas chromatography-tandem mass spectrometry (GC-MS/MS), while non-volatile pesticides are injected into liquid chromatography-tandem mass spectrometry (LC-MS/MS). The new protocol is validated for its linearity (r2), recovery (R), precisions (inter and intra-day), limit of detection (LOD) and limit of quantification (LOQ). It shows good linearity (r2 > 0.99) in the concentration ranging from 0.05 to 150 ng/L. The repeatability and reproducibility of measurements expressed as relative standard deviation (% RSD) is found to be satisfactory (% RSD < 20 %). Furthermore, the detection limits obtained are in the low order of ng/L. Then the developed procedure is tested successfully for its efficiency on real fog samples collected from Erstein (Bas-Rhin, Alsace) and Fnaideq (Akkar, North-Lebanon).

Sorption Kinetics and Sequential Adsorption Analysis of Volatile Organic Compounds on Mesoporous Silica.

Adsorption-desorption behaviors of polar and nonpolar volatile organic compounds (VOCs), namely, isopropanol and nonane, on mesoporous silica were studied using optical reflectance spectroscopy. Mesoporous silica was fabricated via electrochemical etching of silicon and subsequent thermal oxidation, resulting in an average pore diameter of 11 nm and a surface area of approximately 493 m2/g. The optical thickness of the porous layer, which is proportional to the number of adsorbed molecules, was measured using visible light reflectance interferometry. In situ adsorption and desorption kinetics were obtained for various mesoporous silica temperatures ranging from 10 to 70 °C. Sorption as a function of temperature was acquired for isopropanol and nonane. Sequential adsorption measurements of isopropanol and nonane were performed and showed that, when one VOC is introduced immediately following another, the second VOC displaces the first one regardless of the VOC's polarity and the strength of its interaction with the silica surface.

The co-adsorption potential of metal–organic framework/activated carbon composites against both polar and non-polar volatile organic compounds in air

Adsorbents with high surface area and diverse functional groups are regarded as an effective option to deal with volatile organic compounds with different polarities. Herein, a metal–organic framework-199 (MOF-199 (prototypical Cu-MOF))/powdered activated carbon (PAC) composite (MOF-199@PAC) was fabricated and utilized to simultaneously treat multiple VOC system consisting of both non-polar (i.e., benzene) and polar VOCs (i.e., methyl ethyl ketone (MEK)). Kinetic and isotherm models combined with density functional theory simulations were also employed to address the adsorption mechanism of different VOCs onto the MOF-199@PAC composite (e.g., relative to pristine PAC and MOF-199). The overall results suggest that the MOF-199@PAC composite should be used efficiently for the adsorptive removal of polar (e.g., MEK) and non-polar VOCs (e.g., benzene) on its surface with the aid of abundant π-π conjugated sites and polar groups, respectively.

A Critical Review of Emerging Hydrophobic Deep Eutectic Solvents' Applications in Food Chemistry: Trends and Opportunities.

Due to their low cost, biodegradability, and ease of preparation, deep eutectic solvents (DESs) are considered promising green alternatives to conventional solvents, as exploiting green solvents has been a research focus for achieving sustainable development goals. Most DESs in published studies are hydrophilic. On the other hand, the DES's hydrophilicity restricts its practical applicability to just polar molecules, which is a vital disadvantage to this extractant. Hydrophobic DES (HDES) has been developed as a new extractant adept at extracting nonpolar inorganic and organic compounds from aqueous systems. Although there has been little research on HDESs (HDES publications account for <10% of DES), specific intriguing applications have been discovered, requiring investigation and comparisons. As a result, this review covers the applications of emerging HDES in detecting pesticide residues, food additives, contaminants in food packaging, heavy metals, separation and extraction processes in food. According to the available literature, HDESs have the potential to overcome the limitations of hydrophilic DESs and be used in a broader range of applications in food with greater efficiency, which has received little attention. HDES is expected to substitute a lot of harmful organic extractants used for analytical reasons (food chemistry) in the future. Besides, the limitations of HDES were reviewed, and future studies were provided. This will serve as a reference for green chemistry advocates and practitioners in food science who want to minimize pollution and improve efficiency and benefit from the further development of HDESs.

Fabric phase sorpitive extraction and passive sampling of ultraviolet filters from natural waters using a zirconium metal organic framework-cotton composite

In this work, we introduce the use of MOFs immobilized on cotton fabrics as a sorbent phase for the fabric phase sorptive extraction and passive sampling of non-polar organic compounds from water samples. A water-stable, Zr4+-based MOF (UiO-66(Zr)-NH2) was irreversibly immobilized on polydopamine decorated cotton through a step-wise synthetic procedure that maximized the amount of MOF immobilized on the fabric surface. In this manner it was possible to combine the permeability and the large contact surface area of the host cotton substrate with the high specific surface area and sorption capacity of the MOF. The MOF@cotton composite was used as a new sorbent phase for the fabric phase sorptive extraction of UV filters, as model organic compounds, not only under static (i.e. stirring assisted) but also in dynamic, flow-through extraction mode (i.e. as a solid phase extraction sorbent phase), producing satisfactory analytical results in terms of linearity of calibration curves (10–250 µg L−1), precision (<11%), detection limits <10 µg L−1 (using a single wavelength UV detector) and recoveries (86 - 119%) from various natural water samples. As a passive sampling sorbent phase, the MOF@cotton composite could linearly accumulate UV filters over time period of 35 days with sampling rates from 0.026 to 0.352 L d−1, which are comparable to other passive sampling sorbent phases.

The Co-Adsorption Potential of Metal-Organic Framework/Activated Carbon Composites Against Both Polar and Non-Polar Volatile Organic Compounds in Air

The Co-Adsorption Potential of Metal-Organic Framework/Activated Carbon Composites Against Both Polar and Non-Polar Volatile Organic Compounds in Air

Molecular Characterization of Burned Organic Matter at Different Soil Depths and Its Relationship with Soil Water Repellency: A Preliminary Result

Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. This physical property is directly correlated to the erodibility grade of a soil. Wildfire events may develop, enhance, or destroy soil hydrophobicity, modifying the erodibility grade of a soil and increasing the loss of its most reactive layer (organic matter). To assess the main organic family of compounds (biomarkers) surrogates to fire-induced water repellency, a study was carried out on a fire-affected soil under eucalyptus canopy at two depths (0–2 and 2–5 cm) from Portugal. The potential soil water repellency was measured using the water drop penetration time (WDPT) test. The molecular characterization of hydrophobic biomarkers was carried out using analytical pyrolysis (Py-GC/MS) in combination with multivariate statistical analysis (PCA, MLR). The upper burned soil layer (0–2 cm) displayed a significant contribution of fresh biomass (lignin and polysaccharides), while the deepest (2–5 cm) one showed more humified organic matter (lipids). The soil hydrophobicity was directly correlated to non-polar organic compounds, such as lipids and polycyclic aromatic hydrocarbons (PAHs), and inversely to unspecific aromatic compounds. The combination of mass spectrometry techniques and chemometric analysis allowed obtaining a preliminary forecast model of hydrophobicity degree in fire-affected soil samples under eucalyptus canopy. This analytical approach opens the door to developing more sensitive mathematical models using molecular organic compounds to predict the alteration of hydrophobicity and other soil physical properties induced by fires.

Size-fractionated nonpolar organic compounds of traffic aerosol emissions in a highway tunnel

Size-fractionated aerosol samples (PM0.25, PM0.25-1, PM1-2.5, and PM2.5-10) were collected in a highway tunnel in Shanghai, China. The concentrations of nonpolar organic compounds (NPOCs), i.e., n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in the aerosol samples at the tunnel inlet and outlet, emission factors (EFs) of individual NPOCs in PM10, and EFs of size-fractionated individual NPOCs were analyzed comprehensively. NPOC concentrations in this tunnel were lower than the earlier tunnel results, which might be attributed to the tunnel configuration effect on the pollution dilution along the tunnel, in addition to the improvement of engine technology and fuel quality during past decades. n-Alkane homologs for C14–C35 exhibited a smooth hump-like distribution pattern with the most abundance at C22 and 1–2 carbon number shifts of Cmax in comparison to those in other tunnels due to different fleet and fuel compositions. The most abundant PAHs from diesel (e.g., Nap, Phe, Flu and Pyr) and gasoline (e.g., BghiF, BbkF, BeP, DBA and BghiP) vehicle emissions presented concentration increases of 1.8–5.8 times from the tunnel inlet to outlet. The individual n-alkane and PAH distributions exhibited obvious size dependence, while it was expected that the relative abundances and homolog distributions of hopanes were very similar for different size stages. Several diagnostic ratios, e.g., fossil/plant n-alkanes and LMW/HMW PAHs, were evidently size dependent, indicating different sources of size-fractionated n-alkanes and PAHs.

Novel Graphene Wool Gas Adsorbent for Volatile and Semivolatile Organic Compounds.

Volatile and semivolatile organic compounds in ambient air and occupational settings are of great concern due to their associated adverse human health and environmental impacts. Novel graphene wool samplers have been developed and tested to overcome limitations of commercially available sorbents that can only be used once and typically require solvent extraction. Graphene wool (GW) was synthesized by non-catalytic chemical vapor deposition with optimized conditions, resulting in a novel fibrous graphene wool that is very easy to manage and less rigid than other forms of graphene, lending itself to a wide range of potential applications. Here, the air pollutant sampling capabilities of the GW were of interest. The optimal packing weight of GW inside a glass tube (length 178 mm, i.d. 4 mm, o.d. 6 mm) was investigated by the adsorption of vaporized alkane standards on the GW, using a condensation aerosol generator in a temperature-controlled chamber and subsequent detection using a flame ionization detector. The optimized GW packing density was found to be 0.19 mg mm–3 at a flow rate of 500 mL min–1, which provided a gas collection efficiency of >90% for octane, decane, and hexadecane. The humidity uptake of the sampler is less than 1% (m/m) for ambient humidities <70%. Breakthrough studies showed the favorable adsorption of polar molecules, which is attributed to the defective nature of the graphene and the inhomogeneous coating of the graphene layers on the quartz wool, suggesting that the polar versus non-polar uptake potential of the GW can be tuned by varying the graphene layering on the quartz wool substrate during synthesis. Oxidized domains at the irregular edges of the graphene layers, due to a broken, non-pristine sp2 carbon network, allow for adsorption of polar molecules. The GW was applied and used in a combustion sampling campaign where the samplers proved to be comparable to frequently used polydimethylsiloxane sorbents in terms of sampling and thermal desorption of non-polar semivolatile organic compounds. The total alkane concentrations detected after thermal desorption of GW and PDMS samplers were found to be 17.96 ± 13.27 and 18.30 ± 16.42 μg m–3, respectively; thus, the difference in the alkane sampling concentration between the two sorbent systems was negligible. GW provides a new, exciting possibility for the monitoring of organic air pollutants with numerous advantages, including high sampling efficiencies, simple and cost-effective synthesis of the thermally stable GW, solvent-free and environmentally friendly analysis, and, importantly, the reusability of samplers.

Adsorption modeling of organic compounds (OCs) by carbon nanotubes (CNTs): role of OC and CNT properties on the linear solvation energy relationship.

This study evaluated a comprehensive database for the adsorption of polar and nonpolar organic compounds (OCs) by carbon nanotubes (CNTs) and to use the linear solvation energy relationship (LSER) technique for developing predictive adsorption models of OCs by multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). The results showed that coefficient of determinations (R2) values for all compounds are higher variability in the 200 g/mol molecular weight cutoff (74-99%). When the molecular weight cutoff of all OCs is higher than 200 g/mol, the trend of their R2 values is decreased (less than 70%). Among all adsorbate descriptor coefficients, V and B terms are the most significant descriptors (p-values ≤ 0.05) in LSER equations for adsorption of low molecular weight polar and nonpolar OCs by both CNTs. Besides, KOW normalization of all Kd values did not have significant impact on the regression of the LSER model, indicating that hydrophobic interactions are not sole mechanism for the adsorption of OCs on CNTs. Lastly, SWCNTs exhibited higher polar OCs uptake than MWCNTs, which was attributed to more polar surface of SWCNTs as suggested by its high oxygen content (%10).

Strong but reversible sorption on polar microplastics enhanced earthworm bioaccumulation of associated organic compounds

Sorption/desorption of two organic compounds (OCs), phenanthrene (PHE), and 1-nitronaphthalene (1-Nnap) on three polar and one nonpolar polypropylene (PP) microplastics (MPs) and earthworm bioaccumulation of MP associated PHE were systematically studied. Poly-butylene succinate (PBS) with the lowest glass transition temperature (Tg) showed the highest sorption toward PHE and 1-Nnap (Kd: 25,639 ± 276 and 1673 ± 28.8 L kg−1, respectively), while polylactic acid (PLA) with the highest Tg showed the least sorption (182 ± 5 and near 0), confirming that hydrophobic partition was the main driving force of sorption. However, polar interactions also contributed to the preferential sorption of 1-Nnap on polar poly-hydroxyalkanoates (PHA). Moreover, small particle size favored the sorption of MPs and simulated weathering enhanced sorption on MPs with medium/high Tg. As for desorption, slight hysteresis was observed in most cases with near-zero hysteresis index (HI), and PHE generally had higher HI than 1-Nnap. The simulated digestive solution could further promote the desorption of PHE. The PHE concentrations in earthworms with the presence of 5% PBS or PP MPs in soil were 1.50–2.35 or 1.59–1.75 times that of the control without MPs; and PBS MPs with the smallest particle size showed the greatest enhancement. The results of this study confirmed that polar MPs could strongly but reversibly sorb both polar and nonpolar OCs and hence promote the bioaccumulation of OCs to soil organisms.