Different Types Of Organic Compounds Research Articles

Prioritizing Organic Pollutants for Shale Gas Exploitation: Life Cycle Environmental Risk Assessments in China and the US.

Environmental impacts associated with shale gas exploitation have been historically underestimated due to neglecting to account for the production or the release of end-of-pipe organic pollutants. Here, we assessed the environmental impacts of shale gas production in China and the United States using life cycle assessment. Through data mining, we compiled literature information on organic pollutants in flowback and produced water (FPW), followed by assessments using USEtox to evaluate end-of-pipe risks. Results were incorporated to reveal the life cycle risks associated with shale gas exploitation in both countries. China exhibited higher environmental impacts than the US during the production phase. Substantially different types of organic compounds were observed in the FPW between two countries. Human carcinogenic and ecological toxicity attributed to organics in FPW was 3 orders of magnitude higher than that during the production phase in the US. Conversely, in China, end-of-pipe organics accounted for approximately 52%, 1%, and 47% of the overall human carcinogenic, noncarcinogenic, and ecological impacts, respectively. This may be partially limited by the quantitative data available. While uncertainties exist associated with data availability, our study highlights the significance of integrating impacts from shale gas production to end-of-pipe pollution for comprehensive environmental risk assessments.

Preparation of a novel alginate hydrogel microspheres covered by hollow silica for controlled-release application

Sodium alginate hydrogel has been widely used in the field of controlled-release. In this paper, in order to prevent the negative effect of fast degradation and explosive release of pure sodium alginate hydrogel in the drug delivery process, we developed a novel alginate hydrogel supported by hollow silica microsphere for drug delivery. Briefly, the drugs were fused with sodium alginate and the hollow silica microspheres followed by ion crosslinking to form a composite hydrogel microsphere with a core–shell structure (SA@SiO2). The structure and morphology of the composite hydrogel were characterized by Fourier infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM), transmission electron microscope (TEM) along with fluorescence microscope. On this basis, using three different types of organic compounds (rhodamine B, Indocyanine green and salicylic acid) as model molecules, the controlled-release performance of the SA@SiO2 microspheres were investigated in detail. The research results show that the drug delivery system has broad-spectrum controlled-release performance for different types of molecules, and the controlled-release time can exceed 40 h. At the same time, the pH- responsive property of the sodium alginate hydrogel endows the delivery system with a certain targeting function. This study provides a new strategy for constructing an efficient targeted drug controlled-release system.

A Comparison Study on the δD Value of Polycyclic Aromatic Hydrocarbons in Hydrous Pyrolysate of Herbaceous Peat with Different Water Medium

AbstractTo investigate the influence of diagenetic water media on the hydrogen isotopes of individual sedimentary aromatic compounds, a series of hydrous pyrolyses were conducted on herbaceous peat. Polycyclic aromatic hydrocarbons (PAHs) in hydrous pyrolysed samples and their hydrogen isotopic composition characteristics were studied. The aqueous medium demonstrated a significant influence on the hydrogen isotopic composition of the individual PAHs generated during pyrolysis. The results showed that the PAHs formed after pyrolysis in the presence of a saltwater medium with high δD value from a salt lake had a heavy hydrogen isotopic composition. The PAHs formed after pyrolysis in the presence of a fresh water medium with low δD value from a swamp had a light hydrogen isotopic composition. The difference in the average PAH δD value between the two hydrous experiments varied from –174‰ to –109‰, suggesting that the hydrogen isotopic composition of individual sedimentary PAHs can reflect the source of the diagenetic water medium. In addition, a comparative study found that the hydrogen isotopes of PAHs were superior to those of n‐alkanes in the same sample for diagenetic water indications. The results indicated that the exchange of water‐derived inorganic hydrogen and organic hydrogen was more intensive in freshwater experiments than in saltwater experiments. With an increase in the simulation temperature, the average δD value of PAHs generated in the hydrous simulation experiments showed an increasing trend, reflecting that the δD value of sedimentary PAHs formed with the participation of diagenetic water media was still closely related to the thermal maturity of organic matter. Comparative studies showed that the δD values of different types of organic compounds produced by hydrous pyrolysis of peat were in the order, PAHs > n‐alkanes > methane.

Room Temperature Synthesis of Bioactive 1,2,4-Oxadiazoles.

1,2,4-Oxadiazole is an essential motif in drug discovery represented in many experimental, investigational, and marketed drugs. This review covers synthetic methods that allow the conversion of different types of organic compounds into 1,2,4-oxadiazole at ambient temperature and the practical application of the latter approaches for the preparation of pharmaceutically important molecules. The discussed methods are divided into three groups. The first combines two-stage protocols requiring the preliminary preparation of O-acylamidoximes followed by cyclization under the action of organic bases. The advantages of this route are its swiftness, high efficiency of the cyclization process, and uncomplicated work-up. However, it requires the preparation and isolation of O-acylamidoximes as a separate preliminary step. The second route is a one-pot synthesis of 1,2,4-oxadiazoles directly from amidoximes and various carboxyl derivatives or aldehydes in aprotic bipolar solvents (primarily DMSO) in the presence of inorganic bases. This recently proposed pathway proved to be highly efficient in the field of medicinal chemistry. The third group of methods consists of diverse oxidative cyclizations, and these reactions have found modest application in drug design thus far. It is noteworthy that the reviewed methods allow for obtaining 1,2,4-oxadiazoles with thermosensitive functions and expand the prospects of using the oxadiazole core as an amide- or ester-like linker in the design of bioactive compounds.

Molecular transformation of dissolved organic matter in refinery wastewaters: Characterized by FT-ICR MS coupled with electrospray ionization and atmospheric pressure photoionization

Dissolved organic matter (DOM) in refinery wastewater is an extremely complex mixture of various organic compounds. Using mass spectrometry, it is impossible to characterize all of the DOM molecules with only one ionization source. In this study, negative-ion, electrospray ionization (ESI), positive-ion ESI, and positive-ion atmospheric pressure photoionization (APPI) were coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to analyze the molecular composition of DOM in a refinery wastewater stream during the treatment process. There were obvious differences in the heteroatom composition, number of DOM constituents, and chemical properties in refinery wastewater under the three ionization modes. Acidic CHO and CHOS compounds detected by (−)ESI, basic CHN and CHON compounds detected by (+)ESI, and hydrocarbons detected by (+)APPI were analyzed to determine the molecular transformations that occurred during treatment. In an anaerobic biological treatment process, acidic CHO and CHOS compounds with a high oxygen content were preferentially removed, and acidic CHO and CHOS compounds with a low oxygen content were produced. In an aerobic biological process, acidic CHO and CHOS compounds with a low oxygen content were preferentially removed, and acidic CHO and CHOS compounds with a high oxygen content were produced. The whole biological treatment process has a poor removal efficiency for CHN and CHON compounds, and hydrocarbons. An activated carbon (AC) adsorption process removed different heteroatom compounds mainly with a low oxygen content for acidic and basic compounds. The transformation mechanism of CHO and CHOS compounds in the biological treatment process was analyzed by the Kendrick mass defect (KMD) theory and a mass difference network analysis. In the anaerobic process, large amounts of oxygenated CHO and CHOS compounds were degraded by decarboxylation, deoxydation, demethoxylation, and dehydration reactions, and converted to lower oxygen content compounds. In the aerobic processes, these low oxygen CHO and CHOS compounds mainly underwent carboxylation and oxidation reactions. This study determined the transformation characteristics and mechanisms of different types of organic compounds in refinery wastewater during the treatment process. The results provide guidance for the design and optimization of technologies for refinery wastewater treatment. • Molecular composition of DOM in refinery wastewater was characterized by ESI and APPI FT-ICR MS. • Transformation characteristics and mechanism of different types of compound were investigated. • Biological process could remove acidic CHO and CHOS compounds. • AC adsorption process removed various different heteroatom compounds.

Radiation-induced D-to-H Exchange in Ices Containing Ethane or Benzene: Reactions and Rate Constants

The rate constants for radiation-induced deuterium to hydrogen (D-to-H) exchange were recently measured for CD4 in H2O and C2D6 in H2O at 20 K. In the current study, rate constants for radiation-induced D-to-H exchange were obtained for C6D6 in H2O at 20, 50, and 100 K. The rate constants for D-to-H exchange for an organic molecule in water were found to be an order of magnitude greater for benzene than ethane. Additionally, D-to-H exchange for benzene was found to be far more favorable than the production of any other radiolysis product, a result that contrasts with our previous findings for methane and ethane. Finally, rate constants were obtained for C2D6 in H2O at 50 K. For all ice mixtures, increasing the temperature of the experiment yielded a larger rate constant. There is a notable difference in the magnitude of the response of the rate constant for D-to-H exchange as a function of temperature for C2D6 versus C6D6 containing ices. The results suggest that radiation will have an asymmetric effect on D-to-H exchange between different types of organic compounds and water ice matrices. These results suggest that the radiation history of an extraterrestrial sample will influence the D/H ratios of its organic compounds.

Sensitive determination of auxins in environmental water and peach beverage by hyper crosslinked polymer-based solid-phase extraction with high performance liquid chromatography-fluorescence detection

As plant regulators, auxins can promote plant growth. However, they have toxicity and may cause harm to humans. Due to their low concentrations in food sample matrices, the enrichment and analysis of trace auxins in food samples is a challenging work. In this work, a series of hyper crosslinked polymers (HCPs) were synthesized by Friedel-Crafts acylation to extract four auxins (indole-3-acetic acid, indole-3-propionic acid, indole-3-butyric acid and 1-naphthylacetic acid). Among these HCPs, the QP-TC-HCP, synthesized from p-quaterphenyl (QP) and terephthaloyl chloride (TC), showed the best adsorption performance for the auxins. It was then applied as the adsorbent for the solid-phase extraction of the auxins from environmental water and peach beverage samples, followed by high performance liquid chromatography-fluorescence detection. Under the optimized conditions, the limits of detection were 3.0–12.0 pg mL–1 for environmental water and 18.0–36.0 pg mL–1 for peach beverage sample. The method recoveries of the auxins for the spiked samples were in the range of 85.0–110.0%. The established method provided an alternative approach for the determination of auxins in food samples. In addition, different types of organic compounds were tested for the extraction by the QP-TC-HCP to assess its application potential and adsorption mechanism. It was concluded that the QP-TC-HCP had better extraction performance for the compounds with certain hydrophilicity and more hydrogen bonding sites.

Use of Air-Classification Technology to Manage Mycotoxin and Arsenic Contaminations in Durum Wheat-Derived Products.

Mycotoxins are the most common natural contaminants and include different types of organic compounds, such as deoxynivalenol (DON) and T-2 and HT-2 toxins. The major toxic inorganic elements include those commonly known as heavy metals, such as cadmium, nickel, and lead, and other minerals such as arsenic. In this study, micronisation and air classification technologies were applied to durum wheat (Triticum turgidum ssp. durum L.) samples to mitigate inorganic (arsenic) and organic contaminants in unrefined milling fractions and final products (pasta). The results showed the suitability of milling plants, providing less refined milling products for lowering amounts of mycotoxins (DON and the sum of T-2 and HT-2 toxins) and toxic inorganic elements (As, Cd, Ni, and Pb). The results showed an As content (in end products) similar to that obtained using semolina as raw material. In samples showing high organic contamination, the contamination rate detected in the more bran-enriched fractions ranged from 74% to 150% (DON) and from 119% to 151% (sum of T2 and HT-2 toxins) as compared to the micronised samples. Therefore, this technology may be useful for manufacturing unrefined products with reduced levels of organic and inorganic contaminants, minimising the health risk to consumers.

Particle engineering of magnesium ethoxide-based Ziegler-Natta catalyst through post-modification of magnesium ethoxide

A synthetic scheme for particle engineering of magnesium ethoxide (Mg(OEt)2) as a solid precursor for olefin polymerization catalysts was presented based on the exploitation of various organic compounds as a modulator in a post-addition step. It was found that the introduction of a modulator after the particle formation helped to modulate the macroscopic features and the crystalline structure of Mg(OEt)2 to the great extent without destructing the macroparticle morphology. Different types of organic compounds were exploited and their influences on the Mg(OEt)2 structural features were investigated. It was found that organic compounds with higher polarity caused strong modulation of Mg(OEt)2, which allowed particle and pore engineering of the final catalyst, and in turn its performance in propylene polymerization.

Physicochemical Properties and Photochemical Reactions in Organic Crystals

Background:Molecular organic photochemistry is concerned with the description of physical and chemical processes generated upon the absorption of photons by organic molecules. Recently, it has become an important part of many areas of science: chemistry, biology, biochemistry, medicine, biophysics, material science, analytical chemistry, among others. Many synthetic chemists are using photochemical reactions in crystals to generate different types of organic compounds since this methodology represents a green chemistry approach.Objective & Method:Chemical reactions in crystals are quite different from reactions in solution. The range of organic solid state reactions and the degree of control which could be achieved under these conditions are quite wider and subtle. Therefore, for a large number of molecular crystals, the photochemical outcome is not the expected product based on topochemical principles. To explain these experimental results, several physicochemical factors in crystal structure have been proposed such as defects, reaction cavity, dynamic preformation or photoinduced lattice instability and steric compression control. In addition, several crystal engineering strategies have been developed to bring molecules into adequate orientations with reactive groups in good proximity to synthesize complex molecules that in many cases are not available by conventional methods. Some strategies involve structural modifications like intramolecular substitution with different functional groups to modify intermolecular interactions. Other strategies involve chemical techniques such as mixed crystal formation, charge transfer complexes, ionic and organometallic interactions. Furthermore, some examples of the single crystal to single crystal transformations have also been developed showing an elegant method to achieve regio and stereoselectivity in a photochemical reaction.Conclusion:The several examples given in this review paper have shown the wide scope of photochemical reactions in organic molecular crystals. There are several advantages of carrying photochemical reaction in the solid state. Production of materials unobtainable by the traditional solution phase reactions, improved specificity, reduction of impurities, and enhancement in the yields by the reduction of side reactions. These advantages and the multidisciplinary nature of solid-state photochemistry make this discipline quite likely to develop a lot in the future.

Solid phase extraction of carbamate pesticides with porous organic polymer as adsorbent followed by high performance liquid chromatography-diode array detection

A solid phase extraction (SPE) method with a porous organic polymer as adsorbent was established for the extraction of five carbamate pesticides (metolcarb, carbaryl, isoprocarb, bassa and diethofencarb) from milk, white wine and juice samples prior to high performance liquid chromatography-diode array detection. The main factors affecting the SPE were optimized, including sample volume, sample loading rate, sample solution pH, desorption conditions and cartridge reusability. Under the optimal conditions, a good linearity existed in the range from 1.0 to 320.0 ng mL−1 for milk and white wine samples and from 0.5 to 160.0 ng mL−1 for juice sample with the correlation coefficients between 0.9956 and 0.9998. The method recoveries of the carbamates were 82.0%–110.0%. The limits of detection were 0.12-0.40 ng mL-1 for milk and white wine samples, and 0.06-0.20 ng mL−1 for juice sample. The adsorption mechanism of the adsorbent was investigated by the extraction of different types of organic compounds (carbamates, benzoylurea insecticides, endocrine disrupting chemicals and polycyclic aromatic hydrocarbons) with the adsorbent. The results showed that the existence of the hydrogen-bonding between the adsorbent and the analytes is favorable for the adsorption and strong hydrophobicity seems to have an adverse effect.

Mechanochemical synthesis of covalent organic framework for the efficient extraction of benzoylurea insecticides

A covalent organic framework named TpAzo was successfully fabricated by a simple and environmentally friendly mechanochemical grinding method based on the Schiff base aldehyde-amine condensation reaction between 1,3,5-triformylphloroglucinol (Tp) and 4,4′-azodianiline (Azo), with p-toluene sulphonic acid as a molecular organizer. The TpAzo was characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The TpAzo possessed a sheet-like morphology, rich porosity and high thermal stability. The extraction performance of the TpAzo was investigated by using it as the solid phase extraction adsorbent for the extraction of benzoylurea insecticides (BUs) from juice, tomato and white radish samples prior to high performance liquid chromatographic analysis. Under the optimal conditions, a good linearity for the BUs existed in the range of 1.0–160.0 ng mL−1 for juice sample and 0.5–80.0 ng g−1 for tomato and white radish samples with the correlation coefficients of 0.9956–0.9999. The limits of detection for the analytes were 0.1–0.2 ng mL−1 for juice sample and 0.05–0.1 ng g−1 for tomato and white radish samples. The method recoveries for the analytes fell in the range of 84.1%–108.6%. The adsorption mechanism of the TpAzo was investigated by using it to extract different types of organic compounds, including phthalates, phenylurea herbicides and carbamate insecticides. The results showed that the π-stacking and hydrophobic interactions between the TpAzo and the analytes played an important role for the adsorption.

Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5 × 10−4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

Domino-reactions of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide, hetarenecarbaldehydes and active methylene nitriles in the construction of new 2-amino-4H-pyrans and the study of their antimicrobial properties

Multicomponent domino reactions are an effective modern approach in the synthesis of different types of organic compounds, including biologically active pyrans.Aim. To study the three-component interaction of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide with different hetarenecarbaldehydes and active methylene nitriles in order to synthesize new 2-amino-4H-pyran derivatives, as well as the antimicrobial activity of the compounds obtained.Results and discussion. 2-Amino-4-heteryl-4,6-dihydropyrano[3,2-c][2,1]benzoxathiin-3-carbonitrile 5,5-dioxides were obtained by stepwise and multicomponent reactions of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide with hetarenecarbaldehydes and malononitrile. For the same interaction with ethyl cyanoacetate the reaction selectivity decreased and not only target ethyl 2-amino-4H-pyran-3-carboxylates were obtained, but also triethylammonium salts of bis(1,2-benzoxathiin-2,2-dioxo-4-ol-3-yl)(heteryl)methane. The latter were also purposefully synthesized by the two-component reaction of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide with hetarenecarbaldehydes in the presence of triethylamine. The compounds obtained revealed a higher antimicrobial activity against gram-positive bacteria and fungi compared to the reference drugs.Experimental part. 3-Amino-4-heteryl-4,6-dihydropyrano[3,2-c][2,1]benzoxathiin-3-carbonitrile 5,5-dioxides and triethylammonium 3-[1-(4-hydroxy-2,2-dioxido-1,2-benzoxathiin-3-yl)heteryl]-1,2-benzoxathiin-4-olate 2,2-dioxides were synthesized. The antimicrobial activity of the compounds synthesized was studied by the agar diffusion method.Conclusions. It has been proven that the multicomponent format for the three-component interaction of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide with hetarenecarbaldehydes and active methylene nitriles is more favorable and convenient than the stepwise approach to obtain new derivatives of 2-amino-4H-pyrans. Triethylammonium 3-[(4-hydroxy-2,2-dioxido-2,1-benzoxathiin-3-yl)heteryl]-2,1-benzoxathiin-5-olate 2,2-dioxides have been also synthesized. The antimicrobial properties of the compounds obtained are higher than in the reference drugs, especially against gram-positive bacteria and fungi.

Preparation of a magnetic porous organic polymer for the efficient extraction of phenylurea herbicides

A magnetic porphyrin-based porous organic polymer (M-PPOP) with good porosity, high surface area and strong magnetism was prepared and employed as the adsorbent for the magnetic solid phase extraction of the phenylurea herbicides (metoxuron, monolinuron, chlorotoluron, and buturon) from bottled grape juice and tomato samples prior to their determination by high performance liquid chromatography. Under the optimized conditions, the developed method exhibited a good linear range, low limits of detection, low relative standard deviations (<6.8%), good method recoveries between 80.8% and 117%, and high enrichment factors (51–106). For a better elucidation of the adsorption of the M-PPOP towards the analytes, the extraction performance of the M-PPOP for different types of organic compounds including polycyclic aromatic hydrocarbons, phenylurea insecticides, phenylurea herbicides and phenols was studied. The results indicated that the π- stacking, hydrogen-bonding and hydrophobic interactions between the M-PPOP and the analytes played a main role for the adsorption. The results revealed that the M-PPOP material had a great potential for the enrichment of more organic pollutants from real samples.

An Imaging Mass Spectrometry Study on the Formation of Conditioning Films and Biofilms in the Subsurface (Äspö Hard Rock Laboratory, SE Sweden)

Conditioning films and biofilms forming on surfaces of solid materials exposed to aqueous media play a key role in in the interaction between the geo- and biospheres. In this study, time-of-flight secondary ion mass spectrometry and scanning electron microscopy were used to investigate the time scale, mode of formation, and chemistry of conditioning films and biofilms that formed on Si substrates exposed to aquifer water in the subsurface Äspö Hard Rock Laboratory, SE-Sweden. The detection of fragment ions of amino acids, carbohydrates, and carboxylic acids revealed that different types of organic compounds had adhered to the Si surface already after 10 min of exposure to the aquifer fluids, whereas the attachment of microbial cells was first observed after 1000 min. The organic compounds first formed isolated μm-sized accumulations and subsequently started to distribute on the wafer surface more homogenously. Simultaneously further microorganisms attached to the surface and formed biofilm-like cell accumulations after 3 months of exposure to aquifer water.

Biotic and abiotic oxidation and reduction of iron at circumneutral pH are inseparable processes under natural conditions

Oxidation and reduction of iron can occur through abiotic (chemical) and biotic (microbial) processes. Abiotic iron oxidation is a function of pH and O2 concentration. Biotic iron oxidation is carried out by a diverse group of bacteria, using O2 or NO3 as terminal electron acceptors. At circumneutral pH, both processes occur at similar rates and compete with each other. Abiotic iron reduction is catalyzed by iron-sulfur minerals or different types of organic compounds, whereas biotic iron reduction is carried out by a diverse group of microorganisms, often using chemical agents to dissolve solid iron minerals. We used iron oxidizing microbial mats to assess the potential impact of microbial activity on the deposition of banded iron formations (BIF). The mats were collected during several years from experimental tanks connected to groundwater aquifers with different Fe2+ concentrations. To separate between biotic and abiotic iron oxidation, live and killed mats were incubated with 57Fe2+. Separate analyses of the water and solid phase revealed that the iron oxidation and reduction rates per mL of solid matter (biomass and iron precipitates) were 0.4-73 mmol L−1 d−1 and 30–280 mmol L−1 d−1, respectively. No significant differences in iron oxidation rates were observed between the live and killed samples. The iron reduction rates, however, were higher in the live samples in mats from 3 out of 4 environments. We suggest that in natural systems, in the presence of organic matter, biotic and abiotic iron oxidation and reduction are not separable processes. Fe2+ will be biotically and abiotically oxidized as well as bind to exposed charged groups of organic substances. Either way, this iron may serve as a nucleation matrix for further abiotic iron precipitation. The oxidized iron is then susceptible to iron reduction, which can likewise be a direct metabolic or an abiotic process. Nevertheless, it is important to note the significance of organic matter, since both the abiotic oxidation and reduction of iron are often mediated by substrates of biological origin.

Organics and nitrogen removal from textile auxiliaries wastewater with A2O-MBR in a pilot-scale

The removal of organic compounds and nitrogen in an anaerobic–anoxic–aerobic membrane bioreactor process (A2O-MBR) for treatment of textile auxiliaries (TA) wastewater was investigated. The results show that the average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen (NH4+–N) and total nitrogen (TN) were about 119, 3 and 48mg/L under an internal recycle ratio of 1.5. The average removal efficiency of COD, NH4+–N and TN were 87%, 96% and 55%, respectively. Gas chromatograph–mass spectrometer analysis indicated that, although as much as 121 different types of organic compounds were present in the TA wastewater, only 20 kinds of refractory organic compounds were found in the MBR effluent, which could be used as indicators of effluents from this kind of industrial wastewater. Scanning electron microscopy analysis revealed that bacterial foulants were significant contributors to membrane fouling. An examination of foulants components by wavelength dispersive X-ray fluorescence showed that the combination of organic foulants and inorganic compounds enhanced the formation of gel layer and thus caused membrane fouling. The results will provide valuable information for optimizing the design and operation of wastewater treatment system in the textile industry.

Relationship between mercury and organic carbon in sediment cores from Lakes Qinghai and Chenghai, China

Factors such as organic matter can significantly influence the distribution of mercury (Hg) in aquatic environments. Recent studies in Arctic and sub-Arctic lakes in Canada have investigated whether scavenging of Hg by phytoplankton significantly affects distributions of Hg in sediments. This study examined the relationships between Hg and organic components in two contrasting lakes (Lakes Qinghai and Chenghai) in low and middle latitudes of China. Sediment cores from the less-polluted, oligotrophic Lake Qinghai (QH) and from the polluted, eutrophic Lake Chenghai (CH) were collected by a gravity corer. The cores were sectioned and transported on ice to the laboratory where they were stored at −20 °C. Subsamples were dried in a vacuum freeze dryer and grounded with a mortar and pestle prior to analyses. Total concentrations of Hg were quantified using cold vapor atomic absorption spectrometry. Total organic carbon (TOC) was quantified using an elemental analyzer after removal of carbonate. The Rock-Eval 6 pyrolysis technique (Vinci Technologies, Rueil-Malmaison, France) was used to deconvolute TOC in sediments into S1, S2, and RC components; S2 was further separated into S2a and S2b. Different relationships between Hg and TOC were found in the two lakes, which suggest that different types of organic compounds might play completely different roles in the distribution of Hg in lakes. S1 (the soluble organic matter (SOM)) was found to significantly control distributions of Hg in sediments of both lakes, while S2 and S2a were not. Combining the synchronous fluctuations of Hg and the oxygen index in the QH sediment core and in recent sections of CH suggested that allochthonous SOM derived from the terrestrial environment had an important influence on the distribution of Hg in both lakes and a large portion of Hg that originated from the lake catchment. This study provides further evidence that organic matter is one of the most important factors that influences distributions of Hg in lake sediments and that SOM was the primary form of carbon associated with sedimentation of Hg. The results also suggest that Hg in lake sediments might not accurately represent its pollution history as it could also be influenced by land use, such as agriculture or other human activities in the catchment.

Recent Advances in Activation of Silicon Bonds by Fluoride Ion / Jaunākie Sasniegumi Silīcija Saišu Aktivācijās Ar Fluorīda Jonu

Recent advances in the fluoride ion-mediated reactions of silanes containing Si-H, Si-F, Si-C, Si-O, Si-N, Si-Sn bonds are described. Application of silicon bond activation by fluoride ion in the syntheses of different types of organic compounds has been discussed. The literature data published from January 2009 to December 2011 are discussed in this review.