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Roasting is an important step in the pretreatment of biomass upgrading. Roasting can improve the fuel quality of biomass, reduce the O/C and H/C ratios in the biomass, and provide the biomass with a fuel quality comparable to that of lignite. Therefore, studying the structure and component evolution laws during biomass roasting treatment is important for the rational and efficient utilization of biomass. When the roasting temperature is 200–300 °C, the cellulose and hemicellulose in the biomass undergo a depolymerization reaction, releasing many monocyclic aromatic hydrocarbons with high reactivity. The proportion of monocyclic aromatic hydrocarbons in biomass roasting products can be effectively regulated by controlling the reaction temperature, residence time, catalyst, baking atmosphere, and other factors in the biomass roasting process. This paper focuses on the dissociation law of organic components in the pretreatment process of biomass roasting.

Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene.

Monocyclic aromatic hydrocarbons like Benzene, toluene, ethylbenzene and xylene (BTEX) are among environmental pollutants that are considered among chemicals of concern. They are often found in industrial effluents, which when discharged into farmlands end up contaminating the soils. Such happenings warrant the remediation of the soil for environmental sustainability. Solvent extraction, prominent among the techniques employed for this remediation, is limited by the type of solvent used, as volatile organic solvents end up producing secondary pollutants. Various kinds of green solvents like Ionic Liquids (ILs) and Deep Eutectic Solvents (DESs) have been used in this technique as replacements for the conventional ones. In this study, DES made from choline chloride and ethylene glycol in the ratio of 1:2 was synthesized, characterized and used for the remediation of soils contaminated with monocyclic aromatic hydrocarbons (BTEX). Response surface methodology was employed to model and optimize the extraction process. Extraction efficiencies of 76.25, 79.04, 81.93 and 78.66% were obtained for benzene, toluene, ethylbenzene and xylene in a single stage extraction at optimum condition of 45 minutes, 0.841 and 440 rpm for extraction time, solvent mass fraction and mixing rate respectively. Further studies on the solvent regeneration and reuse were conducted. The findings showed that the solvent has capacity to perform effectively in two (2) successive extraction cycles without regeneration, and can undergo up to five (5) cycles upon regeneration without significant loss in its extracting ability. These studies show the possibility of remediating soils contaminated with BTEX using DES under mild extraction conditions.

Phenol, a monocyclic aromatic hydrocarbon with various commercial uses, is a major pollutant in industrial wastewater. Euglena gracilis is a unicellular freshwater flagellate possessing secondary chloroplasts of green algal origin. This protist has been widely used for monitoring the biological effect of various inorganic and organic environmental pollutants, including aromatic hydrocarbons. In this study, we evaluate the influence of different phenol concentrations (3.39 mM, 3.81 mM, 4.23 mM, 4.65 mM, 5.07 mM, 5.49 mM and 5.91 mM) on the growth, morphology and cell division of E. gracilis. The cell count continually decreases (p < 0.05–0.001) over time with increasing phenol concentration. While phenol treatment does not induce bleaching (permanent loss of photosynthesis), the morphological changes caused by phenol include the formation of spherical (p < 0.01–0.001), hypertrophied (p < 0.05) and monster cells (p < 0.01) and lipofuscin bodies. Phenol also induces an atypical form of cell division of E. gracilis, simultaneously producing more than 2 (3–12) viable cells from a single cell. Such atypically dividing cells have a symmetric “star”-like shape. The percentage of atypically dividing cells increases (p < 0.05) with increasing phenol concentration. Our findings suggest that E. gracilis can be used as bioindicator of phenol contamination in freshwater habitats and wastewater.

The effect of cobalt supported on the hierarchical Ni/HZSM-5 on conversion, n-paraffin/aromatic selectivity, the degree of hydrocracking and polymerization in hydrocracking of Sunan candlenut oil was investigated. The hierarchical HZSM-5 was obtained through desilication with 0.2 M NaOH solution. The cobalt (Co), nickel (Ni) and Co-Ni supported on hierarchical HZSM-5 catalysts were prepared by incipient wetness impregnation. Desilication and metal impregnation did not change the crystalline structure of HZSM-5 catalyst. Hydrocracking of Sunan candlenut oil into gasoil-range hydrocarbon was tested with the catalysts at a temperature of 400 °C, and a reactor pressure of 15 bar for 2 h under initial hydrogen pressure in a pressured batch reactor. All catalysts reached conversion almost 100 %. Non-catalytic hydrocracking contained large amounts of undesired compounds (50 %), N-containing compounds around 1 area% and a small amount of compound containing oxygen including ketone (2-heptadecanone) and alcohol (<1%). The addition of cobalt supported on the hierarchical Ni/HZSM-5 improved C15/C16 ratio up to 11, the n-paraffin selectivity up to 78% and decreased polycyclic aromatic hydrocarbons (2-3.7 %). Then, N-containing compounds were not detected. The degree of hydrocracking decreased from 0.28 to 0.23. These results indicated that cobalt could control hydrogenation ability of nickel. The presence of cobalt in the hierarchical Co-Ni/HZSM-5 catalyst increased catalytic activity in decarboxylation route to produce the most abundant n-paraffin, i.e. pentadecane (n-C15) and heptadecane (n-C17). Overall, the monocyclic aromatic hydrocarbons selectivity produced for hierarchical pore structure based HZSM-5 catalyst were 15-18 %.

Physicochemical properties are essential characteristics of organic compounds, which not only impact the fate of organic pollutants but also determine their application in biological processes. Here, we first found that the dielectric constants ( ɛ ) of organic pollutants negatively correlated to their strength for enhancing microbial Fe(III) reduction. Those with lower ɛ values than 2.61 potentially promoted the above process following the sequence carbon tetrachloride (CT) > benzene > toluene > tetrachloroethylene (PCE) due to their different ability to deprotonate the phosphorus-related groups on the outer cell membrane of iron-reducing bacteria Shewanella oneidensis MR-1 (MR-1). The stronger deprotonation of phosphorus-related groups induced more negative charge of cell surface and more strongly increased cell membrane permeability and consequently stimulated faster release of flavin mononucleotide (FMN) as an electron shuttle/cofactor for Fe(III) reduction. These findings are significant for understanding the biogeochemistry in multi-organic contaminated subsurface and providing knowledge for remediation strategies and current production.

The fate of benzene, ethylbenzene, toluene, xylenes (BTEX) compounds through biodegradation was investigated using two different bacteria, Ralstonia picketti (BP-20) and Alcaligenes piechaudii (CZOR L-1B). These bacteria were isolated from extremely polluted soils contaminated with petroleum hydrocarbons. PCR and Fatty Acid Methyl Ester (FAME) were used to identify the isolates. In this study, BTEX biodegradation, applied as a mixture or as individual compounds by the bacteria was evaluated. Both bacteria were shown to degrade each of the BTEX compounds individually and in mixture. However, Alcaligenes piechaudii was a better degrader of BTEXs both in the mixture and individually. Differences between BTEX biodegradation in the mixture and individually were observed, especially in the case of benzene. The degradation of all BTEXs in the mixture was lower than the degradation of individual compounds for both bacteria tested. In the all experiments, toluene and m + p- xylenes were better removed than the other BTEXs. No intermediates of biodegradation were detected. Biosurfactant production was observed by culture techniques. In addition, 3-hydroxy fatty acids, important in biosurfactant production, were observed by FAME analysis. The test results indicate that the bacteria could contribute to bioremediation of aromatic hydrocarbon pollution.

Mixing ratios of seven monocyclic aromatic hydrocarbons, as well as NO₂, SO₂ and O₃, were measured by long path differential optical absorption spectroscopy (DOAS) at a suburban site in Kathmandu, Nepal, during Jan.-Feb. 2003. The results showed average benzene (3.9 ± 1.8 ppbv), toluene (13.3 ± 7.1 ppbv), and sum of xylene isomers (42.2 ± 15.7 ppbv) mixing ratios in Kathmandu. The xylenes concentrations were higher than in the large cities that have been studied. The observed ratio of toluene to benzene (2.9 ± 1.8) reflected the small fraction of vehicles with catalytic converters in the Kathamndu. Analysis of the late afternoon time series of aromatics, NO x , and wind data indicated that road traffic was one of the main sources of aromatics in the urban air. In addition, the correlations between aromatics, SO₂, NO x , and PM₁₀ during the night strongly suggested that fossil and biomass fuel burning made an important contribution to air pollution in the Kathmandu valley. Aromatic pollution was further strengthened by daily recurring stable meteorological conditions and the surrounding topography. The chemical reaction of aromatics with free radicals during the daytime could also be deduced. High ratios of phenol/benzene and para-cresol/toluene could not be explained by chemical processes, and suggested direct emission of phenol and para-cresol in the Kathmandu atmosphere.

The previously reported 1-(2,4-dihydroxy-5-methylphenyl)ethan-1-one (1), (1’Z)-2-(1’,5’-dimethylhexa-1’,4’-dieny1)-5-methylbenzene-1,4-diol (2), and 1,8-epoxy-1(6),2,4,7,10-bisaborapentaen-4-ol (5) together with four new structures of aromatic bisabolane-related compounds (3, 4, 6, 7) were isolated from the marine sponge Myrmekioderma sp. Compounds 1, 2, and 5 were identified based on spectral data available in the literature. The structures of the four new compounds were experimentally established by 1D and 2D-NMR and (−)-HRESIMS spectral analysis. Cytotoxic and lipid-reducing activities of the isolated compounds were evaluated. None of the isolated compounds were active against the tested cancer cell lines; however, lipid-reducing activity was found for compounds 2–5 and 7 in the zebrafish Nile red fat metabolism assay. This class of compounds should be further explored for their suitability as possible agents for the treatment of lipid metabolic disorders and obesity.

The effect of anionic and nonionic surfactants on the sorption and micellar solubilization of monocyclic aromatic compounds in soil-free and soil-water systems was investigated at 25°C to examine the feasibility of in situ remediation. Benzene, chlorobenzene and styrene (BCS) were selected as the target compounds due to their suspected carcinogenic and mutagenic properties. Sodium dodecyl sulfate (SDS) and Triton X-100 were used to represent the anionic and nonionic surfactants, respectively. The addition of Triton X-100 had little effect on the micellar solubilization of BCS. However, the solubilization of aromatic compounds increased significantly with the increase of SDS concentration. A 20% to 43% enhancement of the solubilization in SDS-amended systems was demonstrated. The adsorption isotherms of BCS with Triton X-100 can conveniently be fitted by Langmuirian expression. However, multilayer adsorption of chlorobenzene and styrene was observed in SDS-amended systems. The values ofmaximum adsorption capacity ranged from 323 to 736 μg/g. Also, the effect ofTriton X100 on maximum adsorption capacity was greater than that of SDS. Moreover, a correlation between the maximum sorption capacity and partition coefficient was established. The results of this study demonstrate that surfactants can be effectively used as chemical amendments to minimize the volatilities of monocydic aromatic compounds and enhance sorption and solubilization in soil environments contaminated by proper selection of surfactant type and concentration.