Investigation on Compositional Structures of the Organic Matter and Biomarker Distributions in Shengli Lignite.

The structural characteristics of the organic matter and biomarker distributions in Shengli lignite (SL) were comprehensively studied by combining a variety of modern analytical techniques and solvent extraction/thermal dissolution. Characterization of SL with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid 13C nuclear magnetic resonance spectroscopy and thermogravimetry showed that organic matter in SL is rich in oxygen functional groups, such as C-O, >C=O, and -COOH, and hydrogen bonds. The hydrogen bonds mainly include -OH···π, self-associated -OH, -OH···ether O, tightly bound cyclic -OH, -OH···N, -COOH dimers, and -SH···N. The highest content of organic nitrogen and sulfur on SL surface are pyrrole nitrogen and aromatic sulfur, respectively. The proportions of aromatic and aliphatic carbons in SL are about 58% and 39%, respectively. The aromatic carbon is mainly composed of protonated aromatic and aromatic bridged carbons; methylene carbon has the highest content among the aliphatic carbons, with chains of average length of 1.43 carbon atoms. The average number of aromatic structural units in the carbon skeleton of SL is about 3, and each aromatic structural unit contains an average of 1-2 substituent groups. Thermogravimetric analysis clarified the distribution of the main types of covalent bonds in SL and their possible cracking temperatures during pyrolysis. The extracts and soluble portion of thermal dissolution from SL were analyzed by a gas chromatograph/mass spectrometer, and a series of biomarkers were identified, mainly concentrated in petroleum ether extract and cyclohexane thermal soluble portion. These included long-chain n-alkanes, isoprenoid alkanes, long-chain n-alkenes, terpenoids, n-alkan-2-ones, long-chain n-alkylbenzene, and long-chain n-alkyltoluene. The comprehensive characterization of the organic matter and the distribution of related biomarkers provided an important scientific basis for understanding the molecular structural characteristics and geochemical information on SL.

Corrigendum: Contaminants from a former Croatian coal sludge dictate the structure of microbiota in the estuarine (Rasa Bay) sediment and soil.

[This corrects the article DOI: 10.3389/fmicb.2023.1126612.].

Contaminants from a former Croatian coal sludge dictate the structure of microbiota in the estuarine (Rasa Bay) sediment and soil.

Introduction: Croatian superhigh-organic-sulfur Rasa coal had been mined for nearly 400 years. The release of hazardous trace elements (HTEs) and toxic organic pollutants (TOPs) into the local environment by coal mining, preparation, and combustion activities has resulted in pollution. Methods: In this study, the diversity and composition of microbial communities in estuarine sediment and soil samples as well as community function responses to the pollutants were investigated. Results: The results showed that PAH degradation does occur following 60 years of natural attenuation, the location is still heavily polluted by polycyclic aromatic hydrocarbons (PAHs) and HTEs. Microbial analyses have shown that high concentrations of PAHs have reduced the diversity and abundance of microbial communities. The pollution exerted an adverse, long-term impact on the microbial community structure and function in the brackish aquatic ecosystem. Microorganisms associated with the degradation of PAHs and sulfur-containing compounds have been enriched although the diversity and abundance of the microbial community have reduced. Fungi which are believed to be the main PAH degrader may play an important role initially, but the activity remains lower thereafter. It is the high concentrations of coal-derived PAHs, rather than HTEs, that have reduced the diversity and abundance of microbial communities and shaped the structure of the local microbiota. Discussion: This study could provide a basis for the monitoring and restoration of ecosystems impacted by coal mining activities considering the expected decommission of a large number of coal plants on a global scale in the coming years due to growing global climate change concerns.

Enzymatic decolorization of melanin by lignin peroxidase from Phanerochaete chrysosporium.

Skin darkening results as a consequence of the accumulation of skin pigment melanin. To combat this, the amplitude of skin lightening agents are commercially available, most of which inhibit melanin synthesis. Decolorization of melanin is an alternative method of skin lightening. In this study, we show that lignin peroxidase (LiP), an extracellular enzyme purified from Phanerochaete chrysosporium NK-1 isolated from a forest soil can effectively degrade and decolorize melanin in vitro. Decolorization conditions including pH, temperature, incubation time, enzyme concentration, and mediator addition were investigated to optimize the reaction conditions. The results indicate that pH 3, 40 °C, 15 IU/ml, and 10 h incubation were the optimal conditions for the decolorization of the melanin. The use of the mediator, veratryl alcohol was also found effective to enhance the efficacy of the melanin decolonization, with up to 92% decolorization. The scanning electron microscopy results showed void spaces on the treated melanin granules as compared to the untreated sample, indicating the degradation of melanin. Changes in the fingerprint region of the melanin were observed. Between wavenumbers 1500-500 cm-1, for example, the presence of new peaks in the treated melanin at 1513, 1464, and 1139 cm-1 CH2, CH3 bend and C-O-C stretch represented structural changes. A new peak at 2144 cm-1 (alkynyl C≡C stretch) was also detected in the decolorized melanin. The cytotoxicity study has shown that the treated melanin and LiP have low cytotoxic effects; however, the mediator of veratryl alcohol could result in high mortality which suggests that its use should be meticulously tested in formulating health and skincare products. The findings of the study suggest that LiP produced by Phanerochaete chrysosporium has the potential to be used in the medical and cosmetic industries, particularly for the development of biobased cosmetic whitening agents.

Enhanced bioremediation of diesel range hydrocarbons in soil using biochar made from organic wastes.

Hydrocarbon contamination due to anthropogenic activities is a major environmental concern worldwide. The present study focuses on biochar prepared from fruit and vegetable waste and sewage sludge using a thermochemical approach and its application for the enhanced bioremediation (biostimulation and bioaugmentation) of diesel-polluted soil. The biochar was characterized using FTIR (Fourier-transform infrared spectroscopy), elemental analysis, surface area analysis, and pore analysis. Adsorption experiments showed that hydrocarbon degradation was attributed to biological processes rather than adsorption. The study found that various biochar amendments could significantly increase the rate of hydrocarbon biodegradation with removal efficiencies > 70%. Bioaugmentation using cow dung further improved the removal efficiency to 82%. Treatments showing the highest degree of removal efficiency indicated the presence of 27 different bacteria phyla with Proteobacteria and Actinobacteria as the most abundant phyla. The present study concludes that biochar amendments have great potential for enhancing the bioremediation of soils contaminated with diesel range hydrocarbons.

Selective and effective separation of five condensed arenes from a high-temperature coal tar by extraction combined with high pressure preparative chromatography.

An environmentally benign and cost-effective method was designed for isolating and purifying condensed arenes from acetone-extractable portion (AEP) of a high-temperature coal tar through a high pressure preparative chromatograph (HPPC) with different packings, including silica gel, octadecyl silane, octyl bonded silica gel, and diol bonded silica gel. In total, 196 compounds were detected with a gas chromatograph/mass spectrometer from AEP and its eluates. From the eluates, naphthalene, anthracene, phenanthrene, fluoranthene, and pyrene were successfully isolated and purified, and their structures were confirmed by their 1H and 13C nuclear magnetic resonance spectra in addition to their mass spectra. Extraction-HPPC device and solvent recovery process were designed and developed, which can potentially be applied to industrial production because the process is easy-to-operate and ecofriendliness. In addition, the solvents used can be easily recovered and reused, and neither waste water nor other pollutions are emitted.

Rapid analysis of carboxylic acids and esters with a direct analysis in real time ion source.

RATIONALE: Coal oxidation produces carboxylic acids (CAs), including aliphatic acids, benzoic acids, and benzenepolycarboxylic acids, which are important fine chemicals which could be used to understand the structural features of coals. However, detecting CAs usually presents great challenges due to extremely troublesome pretreatments. Therefore, it is essential to develop an analytical method for the rapid detection of CAs from coal oxidation. METHODS: A series of model compounds (MCs) of oxidation products and two practical samples were investigated by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) under three different analytical conditions (ionizing gas temperature, organic solvent, and MC concentration). RESULTS: Ionizing methyl benzoate, dimethyl phthalate, and dimethyl adipate produces typical ions of methyl esters, including [M - OCH3 ]+ , [M + H]+ , and [M + NH4 ]+ . In contrast, the characteristic ions generated from CAs are polymer ions, such as [2 M + NH4 ]+ , [3 M + NH4 ]+ , [4 M + NH4 ]+ , and [5 M + NH4 ]+ , indicating the strong intermolecular hydrogen-bond interaction among CAs. CONCLUSIONS: Results suggest that DART-TOFMS could rapidly analyze CAs or esters in coal oxidation products according to their typical ions to further gain deep insights into the coal structure.

Application of mass spectrometry in the characterization of chemicals in coal-derived liquids.

Coal-derived liquids (CDLs) are primarily generated from pyrolysis, carbonization, gasification, direct liquefaction, low-temperature extraction, thermal dissolution, and mild oxidation. CDLs are important feedstocks for producing value-added chemicals and clean liquid fuels as well as high performance carbon materials. Accordingly, the compositional characterization of chemicals in CDLs at the molecular level with advanced analytical techniques is significant for the efficient utilization of CDLs. Although reviews on advancements have been rarely reported, great progress has been achieved in this area by using gas chromatography/mass spectrometry (GC/MS), two-dimensional GC-time of flight mass spectrometry (GC × GC-TOFMS), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This review focuses on characterizing hydrocarbon, oxygen-containing, nitrogen-containing, sulfur-containing, and halogen-containing chemicals in various CDLs with these three mass spectrometry techniques. Small molecular (< 500 u), volatile and semi-volatile, and less polar chemicals in CDLs have been identified with GC/MS and GC × GC-TOFMS. By equipped with two-dimensional GC, GC × GC-TOFMS can achieve a clearly chromatographic separation of complex chemicals in CDLs without prior fractionation, and thus can overcome the disadvantages of co-elution and serious peak overlap in GC/MS analysis, providing much more compositional information. With ultrahigh resolving power and mass accuracy, FT-ICR MS reveals a huge number of compositionally distinct compounds assigned to various chemical classes in CDLs. It shows excellent performance in resolving and characterizing higher-molecular, less volatile, and polar chemicals that cannot be detected by GC/MS and GC × GC-TOFMS. The application of GC × GC-TOFMS and FT-ICR MS to chemical characterization of CDLs is not as prevalent as that of petroleum and largely remains to be developed in many respects. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:543-579, 2017.

Characterization of a bio-oil from pyrolysis of rice husk by detailed compositional analysis and structural investigation of lignin.

Detailed compositional analysis of a bio-oil (BO) from pyrolysis of rice husk was carried out. The BO was extracted sequentially with n-hexane, CCl(4), CS(2), benzene and CH(2)Cl(2). In total, 167 organic species were identified with GC/MS in the extracts and classified into alkanes, alcohols, hydroxybenzenes, alkoxybenzenes, dioxolanes, aldehydes, ketones, carboxylic acids, esters, nitrogen-containing organic compounds and other species. The benzene ring-containing species (BRCCs) were attributed to the degradation of lignin while most of the rests were derived from the degradation of cellulose and hemicellulose. Along with guaiacyl and p-hydroxyphenyl units as the main components, a new type of linkage was suggested, i.e., C(ar)-CH(2)-C(ar) in 4,4'-methylenebis(2,6-dimethoxyphenol). Based on the species identified, a possible macromolecular structure of the lignin and the mechanism for its pyrolysis are proposed. The BO was also extracted with petroleum ether in ca. 17.8% of the extract yield and about 82.1% of the extracted components are BRCCs.