Polyaromatic Compounds Research Articles

Polyaromatic hydrocarbons of small reservoirs of the Tomsk region

Relevance. The assessment of the state of natural waters includes the determination of a number of physico-chemical indicators, on the basis of which various indices and classifications are developed. However, they do not take into account a number of pollutants that have a significant impact on the state of the reservoir, for example, polyaromatic hydrocarbons. The article considers some aspects of determining priority pollutants, which include polyaromatic hydrocarbons, according to environmental hazard criteria: toxicity, carcinogenicity, prevalence, frequency of occurrence, source of origin (anthropogenic or natural). Hydrochemical parameters such as pH, dissolved oxygen content, biological oxygen consumption (BPK5), and ion content are taken into account to determine water quality. An attempt was made to assess the impact of polyaromatic hydrocarbons on the ecological state of water bodies and to take into account their contribution to changes in the values of the water pollution index. All these data prove the relevance of the study. Aim. To establish the composition of polyaromatic hydrocarbons in the surface waters of small reservoirs of the Tomsk region to assess anthropogenic load and to show the relationship with the indices of natural water quality. Methods. Extraction, liquid adsorption chromatography, high-performance liquid chromatography, capillary electrophoresis, amperometry, titrimetry. Results. Small lakes of the Tomsk region were studied for the content of 13 polyaromatic hydrocarbons. The authors have carried out the identification by high-performance liquid chromatography with fluorimetric detection. The total content of polyaromatic compounds in the studied surface water samples varies from 0.37 to 0.54 mcg/l. In the polyaromatic hydrocarbons mixture in aqueous samples, there is an increased content of light 2–3 nuclear polyarenes with better solubility (naphthalene, fluorene and phenanthrene), as well as benz[a]anthracene. The content of inorganic components represented by cations and anions does not exceed the maximum permissible concentrations. The water pollution index was calculated; all lakes are moderately polluted, closer to polluted. The paper demonstrates the dependence of the water pollution index coefficient on the content of high-molecular polyaromatic hydrocarbons and the ratio of high-molecular to low-molecular polyaromatic hydrocarbons. It is shown that the higher the value of the water pollution index coefficient, the higher the proportion of difficult-to-oxidize components in surface waters.

A new spectral-based index for graphs and its application to polyaromatic compounds

In this study, we introduce a novel index called the modified inverse sum indeg (MISI) energy as an extension of the traditional inverse sum indeg (ISI) energy and neighbor degree sum energy. We devised an algorithm that employs the simplified molecular input line entry system (SMILES) formula of compounds to compute the MISI energy of polycyclic aromatic hydrocarbon (PAH). Additionally, we established the bounds of the MISI energy for certain classes of graphs with fixed number of vertices. A strong correlation between the MISI energy and the total [Formula: see text]-electron energy of PAHs is observed through regression analysis. Remarkably, this correlation outperforms that achieved by the classical ISI energy. These findings highlight the enhanced effectiveness of the MISI energy as a descriptor for capturing significant molecular properties. Moreover, our study establishes a foundation for further theoretical extensions and practical applications in the field of chemical graph theory.

Advancements in green-synthesized transition metal/metal-oxide nanoparticles for sustainable wastewater treatment: techniques, applications, and future prospects

Abstract In order to meet the demand for portable water and replenish depleting water resources caused by industrialization, urbanization, and population growth, wastewater purification has become crucial. Emerging contaminants (ECs), which include organic dyes, pesticides, pharmaceutical drugs, polyaromatic compounds, heavy metal ions, and fertilizers, among others, have caused significant disruptions to environmental balance and severe health complications. As a result, considerable effort has been devoted to the development of technologies that eliminate wastewater from effluents via adsorption, photocatalysis, and other means. However, considering the economic and environmental implications of the adopted technologies, green technology has gained significant attention owing to their eco-friendly approaches, cost-effectiveness, avoiding use of toxic and harmful chemicals and production of less-toxic by-products. Currently green-synthesized nanomaterials have seen tremendous growth in emerging as sustainable nanoadsorbents, nanocatalysts for the removal of the emerging contaminants from wastewater in highly efficient and eco-friendly manner. Thus, this review presents an overview of the various techniques utilized in wastewater treatment with a particular emphasis on the production and application of environmentally friendly transition metal/metal oxide nanoparticles as sustainable tools in wastewater treatment technology. This article also discusses the limitations and future potential of using green-synthesized transition metal/metal oxide based nanoparticles in advancing the technology on a broad scale.

Synthesis and biological properties of small molecules — ligands of non-canonical DNA and RNA structures

Nucleic acids are important targets for many anticancer drugs. Apart from the canonical B-DNA double helix, DNA forms a number of non-canonical structures (G-quadruplexes, i-motifs, hairpins, triplexes, <i>etc</i>.), which play an important role in the regulation of biological processes. Binding to non-canonical DNA structures occurs mainly by π–π-stacking. Therefore, aromatic and heteroaromatic compounds such as fused polyaromatic compounds (acridines, anthraquinones, carbazoles), porphyrins, benzothiazoles, benzimidazoles, pyridines, and quinolines, as well as their complexes are used as ligands for secondary structures. These ligands should possess not only high selectivity for non-canonical structures over double-stranded DNA, but also relatively high solubility and ability to penetrate through cell membranes. This review summarizes the achievements of 2020–2024 in the synthesis and biological studies of (hetero)arenes (acridines, anthraquinones, benzazoles, xanthones, porphyrins) and coordination compounds that have exhibited anticancer activity as a result of binding to non-canonical DNA or RNA structures. Ligands of various types of non-canonical nucleic acid structures (G-quadruplexes, i-motifs, triplexes, hairpins) are considered and their cytotoxic activity and structure–property relationships are compared <br> The bibliography includes 166 references.

Converting a low-cost industrial polymer into organic cathodes for high mass-loading aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) using organic cathodes have emerged as a sustainable energy storage technology benefitting from high safety, low cost, and abundant feedstocks. However, most organic cathodes are n-type polyaromatic compounds and conjugated polymers, which require sophisticated synthesis, provide a low operational voltage and slow Zn2+ diffusion kinetics. Herein, we report access to p-type radical polymer cathodes from a commercially available poly(methyl vinyl ether-alt-maleic anhydride) (poly(MVE-alt-MA)) polymer. The modification of poly(MVE-alt-MA) with 4-amino-TEMPO produces radical polymers (PTEMPO) that are easily scalable to tens of grams. The corresponding polymer AZIBs deliver a capacity of 92 mAh g-1 at 10 C with 95 % capacity retention over 1000 cycles. Importantly, the electrode composites and battery assembly procedure are optimised so that no fluoro-containing electrolytes and binders are needed, and cheap carbon additives can be used. We assemble the Swagelok batteries, small pouch, and large pouch batteries with a high mass-loading of 7.8 to 50 mg cm-2, demonstrating nearly 100 % Coulombic efficiency. The pouch battery with 0.8–0.9 g of active polymer displayed a 60-mAh capacity with 1.5 V operational voltage. This work paves the way for simple and practical implementation of polymer AZIBs for real-world applications.

Processing and Recovery of Heavy Crude Oil Using an HPA-Ni Catalyst and Natural Gas.

To maintain economic profitability and stabilize fuel prices, refineries actively explore alternatives for efficiently processing (extra) heavy crude oils. These oils are challenging to process due to their complex composition, which includes significant quantities of asphaltenes, resins, and sulfur and nitrogen heteroatoms. A critical initial step in upgrading these oils is the hydrogenation of polyaromatic compounds, requiring substantial hydrogen sources. Methane from natural gas streams is known to act as an effective hydrogen donor. This study investigates the use of a heteropolyacid (HPA) catalyst modified with nickel and methane to enhance the quality of heavy crude oil with an initial 8.0°API (at 15.5 °C) and 2200 cSt viscosity (at 37.5 °C). After treatment in a batch reactor at 380 °C and 4.4 MPa for 2 h, the oil properties markedly improved: API gravity increased from 8.0 to 16.0 (at 15.5 °C), and kinematic viscosity reduced from 2200 to 125 cSt (at 37.5 °C). Additionally, there was a significant decrease in asphaltenes (from 38.7 to 16.4% by weight), sulfur (from 5.9 to 4.0% by weight), and nitrogen (from 971 to 695 ppm). This was accompanied by an increase in the volume of light distillates from 1.3 to 4.9%, and middle distillates from 8.8 to 21.0%. These results suggest that nickel-modified HPA catalysts, combined with methane as a hydrogen donor, are a promising option for upgrading heavy crude oils.

Substituted indeno[2,1‐c]fluorene‐5,8‐diones as a platform for synthesis of polyaromatic hydrocarbons possessing extended π‐conjugated systems with butterfly‐like frameworks

Synthetic options for conversion of indeno[2,1‐c]fluorene‐5,8‐diones into larger polyaromatic compounds with extended π‐conjugated systems were explored. The crucial two‐fold transformation of the five‐membered ketone moieties of indeno[2,1‐c]fluorene‐5,8‐diones was based either on a one‐carbon homologation or on a ring‐expansion reaction which eventually enabled syntheses of compounds possessing substituted tribenzo[a,e,l]indeno[1,2,3‐hi]acephenanthrylenes and [5]helicenes scaffolds. The former was prepared by using a reaction sequence based on Ramirez olefination, intramolecular Heck reaction, and intermolecular Suzuki‐Miyaura cross‐coupling, whereas the latter utilized a sequence comprising Büchner−Curtius−Schlotterbeck reaction and intermolecular Suzuki‐Miyaura cross‐coupling. Scholl reaction of selected [5]helicenes yielded planarized polyaromatic compounds with the tribenzo[a,e,l]indeno[1,2,3‐hi]acephenanthrylene scaffold. Where possible, structures of products were confirmed by X‐ray diffraction analyses. Photophysical properties were determined as well.

Heavily polluted mechanic workshop soil and its phenanthrene-degrading Bacillus thuringiensis

Mechanic workshops in residential areas are sites referenced for small-scale chronic contamination with petroleum hydrocarbons (HC) and associated pollutants like heavy metals. The main aim of this study was to isolate from a mechanic workshop soil in Lagos a novel indigenous bacterium with potential for degradation of phenanthrene, a model polyaromatic compound. Gas chromatographic analysis revealed concentrations of HC (20,055 mg kg-1), lead (156.19 mg kg-1) and zinc (202.005 mg kg-1) in excess of regulatory limits in the soil. Continuous enrichment resulted in the isolation of a bacterium strain ALSL2, which was identified by 16S rRNA gene sequencing as Bacillus thuringiensis. Strain ALSL2 showed broad specificity for a range of HCs including phenanthrene, anthracene, biphenyl, dibenzothiophene, crude oil, diesel and kerosene and also showed biosurfactant production with emulsification index 55.2 %, 65.7 % and 58.7 % on crude oil, kerosene and vegetable oil respectively. The isolate showed evidence of dioxygenase activity and utilized metabolites of aromatic hydrocarbon degradation including 1-naphthol and O-phthalate. At the end of 10 days 51.45 % of phenanthrene was degraded at the rate of 7.922 mg l−1 d−1, degradation constant 0.073 d−1, and half-life 9.864 d. The corresponding values for anthracene were 69.11 %, 9.92 mg l−1 d−1., 0.11 d−1, and 5.924 d respectively. Our findings represent a remarkable addition to available indigenous bioresources with potential for application in bioremediation, and further highlight mechanic workshop soils as veritable source of such isolate.

Direct evidence of gas flushing oil in deep reservoirs: Insight from integrated fluid inclusion analyses

Gas flushing of oil has been proposed as an essential process for forming some condensate gas reservoirs based on laboratory experiments and modeling but such a process has rarely been documented in subsurface reservoirs. Here, we report a unique type of yellow-ringed oil inclusions (YROIs) discovered from a deep reservoir in the Kuqa Foreland Basin, Western China that recorded the gas flushing of oil process in the subsurface. The occurrence, composition, phase state and PVT conditions of YROIs during trapping were investigated using a suite of fluid inclusion analytical methods including fluid inclusion petrography, microthermometry, fluorescence spectroscopy, PVT modeling and molecular composition analysis.YROIs found in the reservoir are three-phase (solid–liquid-vapor) fluid inclusions at room temperature with solid rings of 2–3 μm thickness and estimated volume percentages varying between 5 % and 15 %. When heated the solid ring starts to melt at around 46 °C and homogenized with the liquid phase at or above their corresponding homogenization temperatures of coeval aqueous inclusions. YROIs have fluorescence spectral peaks between 530 nm and 550 nm and an elevated spectral shoulder around 650 nm when measured at room temperature; but most spectra show a distinct “blue shift” and an absence of the 650 nm shoulder when measured at their homogenization temperatures. Some YROIs with thick yellow rings show dual spectral peaks at 570 nm and 630 nm at room temperature and their spectral peaks do not change when remeasured at their homogenization temperatures. Molecular compositions derived from synchronous fluorescence spectra and GC-MS analysis suggest that the compositions of YROIs are rich in polyaromatic compounds. PVT modeling indicates that YROIs were trapped under high pressure conditions with a pressure exceeding 50 % of the corresponding hydrostatic pressure.YROIs are interpreted to have been trapped under an elevated temperature and overpressure condition (around 110 °C and 60 MPa) relating to an intensive (wet) gas flushing of an early-charged wax-rich oil. When light hydrocarbon components in the reservoir oil were partially removed by gas, the wax/resin components rich in polyaromatic hydrocarbon compounds may precipitate due to physio-chemical fractionation. YROIs were entrapped in subsurface from a heterogeneous hydrocarbon fluid containing variable amounts of wax/resin colloids, which subsequently coalesce to form solid rings adhering to the inner wall of oil inclusions at room temperature. The presence of yellow-ringed oil inclusions in a reservoir may be indicative of a rapid gas flushing of waxy oil under high pressure, and their minimum homogenization temperature may approximate their trapping temperature.

Exploring the role of air pollution on the development of atherosclerosis disorder in human endothelial cells

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): QU - NSPP Introduction Atherosclerosis, the main cause of cardiovascular and cerebrovascular diseases, is a global health threat. Rising cardiovascular disease prevalence, unexplained by traditional risk factors, prompts exploration of the impact of occupational exposure to environmental toxins as a risk factor. benzo[a]pyrene (BaP) is a polyaromatic compound that mediate its toxicity through activation of the Aryl hydrocarbon receptor (AhR). The molecular mechanisms of involvement of environmental toxins and the role of AhR/CYP1A pathway in atherosclerosis development remain not fully investigated. Purpose The current study explores the AhR pathway activation in endothelial cells upon exposure to environmental toxins in order to elucidate the molecular mechanisms of atherosclerotic cardiovascular diseases and plaque formation through investigating pro-inflammatory (CYP1A1, CYP1B1, TNF-a) and pro-apoptotic markers (BCL-2, Caspase-3). Methods EA. hy926 cell line underwent treatment with increasing concentrations of BaP (0-20 microM), as well as 10nm of TCDD, to confirm the results. DSMO was used as a control. Total RNA and protein were isolated to investigate mRNA expression and protein expression of AhR, CYP1A1, CYP1B1, as well as caspase-3, Bcl-2, and TNF-α using RT-PCR and Western Blot analysis. Statistical analysis was done using one-way ANOVA. Results The results showed that BaP induce significant dose-dependent upregulation of AhR and target genes (CYP1A1, CYP1B1). At 20uM, expression of AhR (3-fold), CYP1A1 (2.5-fold) and CYP1B1 (2-fold) was significantly high as compared to their respective controls and low doses. As for apoptotic markers, Bcl-2 was significantly downregulated at the highest concentrations 10uM and 20uM (0.7- and 0.6-fold, respectively). Caspase-3 showed no significant change but exhibited upregulation across all doses. TCDD 10nM significantly upregulated AhR (2.0-fold), CYP1A1 (1.5-fold), CYP1B1 (1.7-fold). Bcl-2 downregulated (0.6-fold), TNF-α significantly upregulated (1.8-fold) at 10nM. Caspase-3 increased 2-folds but was not statistically significant. Conclusion This study illustrated that AhR inducers, such as BaP, can accelerate the pathological progress of atherosclerosis by evoking oxidative stress and inflammation response molecules in human endothelial cells, demonstrated by the reduced expression of anti-apoptotic markers and the increased expression of inflammatory markers.

Synthesis of an innovative SF/NZVI catalyst and investigation of its effectiveness on bio-oil production in liquefaction process alongside other parameters

Today, new energy sources alternative to fossil fuels are needed to meet the increasing energy demand. It is becoming increasingly important to constitute new energy sources from waste biomass through the liquefaction process. In this study, walnut shells (WS) were liquefied catalytically and non-catalytically under different parameters using the liquefaction method. In this process, the effect of silica fume/nano zero-valent iron (SF/NZVI) catalysts on the conversion rates was investigated. The catalyst was synthesized by reducing NZVI using a liquid phase chemical reduction method on SF. The SF/NZVI catalyst was characterized by scanning electron microscopy- energy dispersive X-ray (SEM–EDX), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. The effect of various process parameters on the liquefaction process was investigated. In this context, the reaction temperature ranged from 300 to 400 °C, the solid/solvent ratio ranged from 1/1 to 1/3, the reaction time ranged from 30 to 90 min, and the catalyst concentration ranged from 1 to 6%. According to the results obtained, the most suitable operating conditions for non-catalytic experiments in liquefaction of WS were found to be temperature of 400 °C, reaction time of 60 min, and solid/solvent of 1/3. In catalytic conditions, the optimum values were obtained as temperature of 375 °C, reaction time of 60 min, solid/solvent ratio of 1/3, and catalyst concentration of 6%. The highest total conversion and (oil + gas) % conversion were 90.4% and 46.7% under non-catalytic conditions and 90.7% and 62.3% under catalytic conditions, respectively. Gas chromatography/mass spectrometry (GC/MS) analysis revealed the bio-oil was mainly composed of aromatic compounds (benzene, butyl-, indane and their derivatives,) and polyaromatic compounds (naphthalene, decahydro-, cis-, naphthalene, 1-methyl-.). The aim of increasing the quantity and quality of the light liquid product in the study has been achieved.

C─H···π interaction induced H‐aggregates for wide range water content detection in organic solvents

AbstractJ‐aggregation and H‐aggregation are identified as two classical models of functionally oriented non‐covalent interactions, and significant attention has been drawn by researchers. However, due to the scarcity of single‐crystal examples of H‐aggregation, a comprehensive understanding of the relationship between its stacking mode and optical behaviour has been hindered. In recent studies, two polyaromatic Schiff base compounds, Cl‐Salmphen and H‐Salmphen, were successfully synthesized, and both were found to exhibit H‐aggregation. In the findings, H‐Salmphen was shown to display typical C─H···π interactions, characteristic of Aggregation‐Induced Emission (AIE) active molecules, whereas its halogenated counterpart was identified as behaving similar to Aggregation‐Caused Quenching (ACQ) active molecules. These types of results suggest that identical intermolecular interactions can produce differing optical behaviours. Light was shed, at least in part, on the formation mechanisms of H‐type aggregates and their luminescence properties from these observations. Additionally, the high optical signal‐to‐noise ratio inherent to H‐aggregates was utilized for the exploration of water content detection. As an outcome, a high‐performance fluorescent filter paper was developed, enabling easy real‐time detection using a smartphone.

Viscosities and Densities of Binary and Ternary Mixtures of Aliphatic and Polyaromatic Hydrocarbons: Pyrene +1-Methylnaphthalene + Dodecane at T = (293.15 to 343.15) K. Experiment and Modeling.

This work presents new experimental viscosity and density data for aromatic and polyaromatic compounds in binary and ternary pyrene, 1-methylnaphthalene, and dodecane mixtures. The lack of experimental viscosity data for these mixtures requires the development of a new database, which is vital for understanding the behavior of mixtures in more complex systems, such as asphaltenes and fuels. The mixtures proposed in this work have been measured over a temperature range of (293.15 to 343.15) K at atmospheric pressure. Several mixture compositions have been studied at these conditions: 1.0, 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0% pyrene mass fraction. The concentration of pyrene correlates with an increase in the viscosity and density values. At the lowest temperature in binary mixtures, the corresponding values reach 4.4217 mPa·s for viscosity and 1.0447 × 103 kg·m-3 for density, respectively. In ternary mixtures, the introduction of dodecane leads to the lowest maximum values of 3.5555 mPa·s for viscosity and 1.0112 × 103 kg·m-3 for density at the same temperature. The experimental data have been employed for the specific modification of viscosity models. These modifications could facilitate the prediction of the viscosity of mixtures that are more complex than those presented in this work. Various viscosity models have been employed, such as Linear, Ratcliff and Khan, modified UNIFAC-Visco, and Krieger-Dougherty. The settings in the models used reliably reproduce the experiment reliably. However, the Ratcliff model agrees excellently with the experiment, having a low standard deviation (2.0%) compared to other models. Furthermore, a model based on the equation of state of Guo is proposed to predict the viscosity values by modifying the specific parameters and adjusting them to the mixtures proposed in this work. The results from this study are compared to previous work, where pyrene, toluene, and heptane mixtures were analyzed. In this case, we find that the decrease of aggregation grade in the present systems is predicted by the model fixed in this work.

Controlling the Photophysical Properties of a Series of Isostructural d6 Complexes Based on Cr0, MnI, and FeII.

Development of first-row transition metal complexes with similar luminescence and photoredox properties as widely used RuII polypyridines is attractive because metals from the first transition series are comparatively abundant and inexpensive. The weaker ligand field experienced by the valence d-electrons of first-row transition metals challenges the installation of the same types of metal-to-ligand charge transfer (MLCT) excited states as in precious metal complexes, due to rapid population of energetically lower-lying metal-centered (MC) states. In a family of isostructural tris(diisocyanide) complexes of the 3d6 metals Cr0, MnI, and FeII, the increasing effective nuclear charge and ligand field strength allow us to control the energetic order between the 3MLCT and 3MC states, whereas pyrene decoration of the isocyanide ligand framework provides control over intraligand (ILPyr) states. The chromium(0) complex shows red 3MLCT phosphorescence because all other excited states are higher in energy. In the manganese(I) complex, a microsecond-lived dark 3ILPyr state, reminiscent of the types of electronic states encountered in many polyaromatic hydrocarbon compounds, is the lowest and becomes photoactive. In the iron(II) complex, the lowest MLCT state has shifted to so much higher energy that 1ILPyr fluorescence occurs, in parallel to other excited-state deactivation pathways. Our combined synthetic-spectroscopic-theoretical study provides unprecedented insights into how effective nuclear charge, ligand field strength, and ligand π-conjugation affect the energetic order between MLCT and ligand-based excited states, and under what circumstances these individual states become luminescent and exploitable in photochemistry. Such insights are the key to further developments of luminescent and photoredox-active first-row transition metal complexes.

Evaluation of industrial aromatic oils as potential hydrogen carriers: Study of the hydrogenation step

Industrial organic streams (oils) with high concentration of aromatics compounds are present in different carbochemical and petrochemical processes. These aromatic compounds are potential hydrogen carriers through hydrogenation-dehydrogenation cycles. For this purpose, catalytic hydrogenation of three different aromatic oils using conventional hydrogenation catalysts is considered in this work. Two oil samples (petrochemical Oil A and carbochemical Oil B) enriched with polyaromatic compounds, along with a manufactured oil of petrochemical origin (SolvessoTM 200), were hydrogenated using Pt/γ-Al2O3 and Pd/γ-Al2O3 catalysts. The study aims to work under mild conditions to avoid secondary reactions and cracking, which is important for using these oils as potential LOHCs. The methodology involved using a stainless-steel autoclave reactor and analysing the composition of the oils and reaction products using gas chromatography and mass spectrometry. Diaromatic compounds were found to be the most reactive, reactant conversion depending on the catalyst and reaction temperature. However, the presence of tri and tetra-aromatic compounds hinder the reaction. Moreover, nitrogenated aromatic compounds are extremely reactive at these conditions. Comparison of SolvessoTM 200 with benzyltoluene, an established LOHC, resulted in promising results. Thus, both Oil A and B, after a purification step, would have interesting qualities to be used as LOHCs with the added advantage of its low price.

Treatment Technologies for Removal of Polyaromatic Hydrocarbon Compounds from Wastewater: A Review

Industry discharges, home effluents, and/or urban runoff can all introduce polyaromatic hydrocarbon compounds (PAHs) into a treatment center. Regrettably, due to their chemical stability and resistance to biological degradation, PAHs are regarded as organic pollutants that persist. As a consequence, PAHs have indeed been identified as a possible source of skin, lung, and bladder cancer in humans. Due to PAHs' potential to cause cancer and/or mutation, their residues in treated wastewater are now subject to stricter legal regulation. adsorption ,membrane filtration, coagulation, electrocoagulation, flocculation, advanced oxidation reactions, phytoremediation and bioremediation process are some of the techniques used to remove PAHs from wastewater. In order to reduce environmental contamination, it is important to study different treatment technologies to treat wastewater. The aim of this paper is to highlighting and discussing some of treatment technologies for removing PAHs.

Synthesis of two nitrogen-containing polyaromatic compounds through gold catalysis/DBU-promoted cyclizations.

This work reports an efficient synthesis of novel benzo[7,8]indolizino[2,3,4,5-ija]quinazoline derivatives between 2-(2-ethynylaryl)acetonitriles 1 and anthranils 2. The synthetic approach involves the initial formation of 7-formylindole intermediates that can be implemented by DBU to activate a novel indole-nitrile-aldehyde cyclization.

Sodium citrate-sodium hydroxide synergy on remediating asphaltene-contaminated solids

Asphaltenes are the heaviest and surface-active polyaromatic compounds in crude oil. Their precipitation and deposition on sand surfaces switch the wettability of sand from water-wet to oil-wet, which is harmful to the oil recovery process. In this study, we demonstrate the synergistic effect between sodium hydroxide (NaOH) and sodium citrate (Na3Cit) on remediating asphaltene-contaminated silica from both experimental and molecular dynamics (MD) simulation perspectives. Asphaltene desorption efficiency increased from 39 % (Na3Cit only) to 84 % (NaOH + Na3Cit), attributed to better remediation of natural silica wettability and reduced silica-asphaltene adhesion with the co-addition chemicals. Fundamental insights for NaOH-Na3Cit synergy were revealed by MD simulation. The bonding between an asphaltene model compound (C5Pe) and the quartz (101) surface became thermodynamically less favorable when both NaOH and Na3Cit were present in the system, forcing the C5Pe molecules to move away from the surface. In summary, we highlight the NaOH-Na3Cit synergy in promoting the asphaltene detachment from silica surfaces, which has important implications in oil recovery and soil remediation applications.

Bacterial Consortium-Mediated Hydrocarbon Degradation of Waste Engine Oils

The automotive and industrial activities are considered one of the important sources of pollution with the increasing amount of WEO released to the environment. One of the ways to solve this problem is through bioremediation. It is, however, challenging since used engine oil contains complex hydrocarbon compounds and is toxic towards the environment and living organisms. Biodegradation by single species bacterium is limited to a small range of hydrocarbon compounds. Hence, a better strategy is to use a synergistic action of different microbial members in a consortium. Different waste engine oils from the motorcycle workshop (MW), urban vehicle workshop (UVW), and heavy vehicle workshop (HVW) were tested for degradation by a bacterial consortium culture. A two-level factorial design experiment was carried out to evaluate the effect of different WEO and nitrogen concentrations towards the growth of the bacterial culture and hydrocarbon degradation in shake flask fermentation. The bacterial consortium culture grown in mineral salts medium (MSM) supplemented with MW (Viscosity, 82 mPa.s) was shown to exhibit the highest biomass with 0.37 (OD600) with 8% (v/v) WEO and 5 g/L nitrogen from ammonium chloride (NH4Cl). Pareto chart of biomass with WEO and nitrogen concentration showed a positive effect for MW and UVW, while a negative effect for HVW which was presumed due to the toxicity, higher complexity of hydrocarbon composition and higher viscosity of WEO from heavy vehicles. Subsequently, GC-MS analysis indicated the degradation of various polyaromatic hydrocarbon (PAH) and BTEX compounds such as naphthalene, benzene, and toluene in the three WEO samples. Assessment of cell hydrophobicity of the culture grown on all three WEO exhibited high cell hydrophobicity, with HVW showing the highest cell hydrophobicity of 81%. This suggests that the bacterial culture altered cell hydrophobicity to facilitate hydrocarbon uptake.

INFLUENCE OF TECHNOLOGICAL PARAMETERS ON THE COMPOSITION AND PROPERTIES OF PETROLEUM COKE

This study is devoted to studying the complex process of producing coke from heavy oil residues using previously developed experimental approaches and using analytical methods of analysis. The purpose of the study is to produce low-sulfur coke by thermal processing of heavy oil residues in the presence of waste motor oils. The resulting coke was analyzed by various physicochemical methods. The composition and structure of the resulting coke were studied using Raman spectroscopy methods. As a result of the analysis, the predominance of polyaromatic compounds and olefins in the coke composition was revealed. Electron microscopy techniques provided a visual representation of the microstructure and morphology of coke samples obtained both in the presence and absence of a recycling agent. Significant results were obtained by measuring the specific surface area of coke, which highlight the significant influence of temperature fluctuations on its characteristics of coke. It is noteworthy that the specific surface area of micropores varies significantly – from 16 to 600 m2/g. The results of the analysis of sulfur content showed the possibility of its thermal dehydration, which should lead to an improvement in the quality of coke. In addition, it has been shown that conducting the experiment in the presence of a recycling agent significantly increases the yield of coke and opens up prospects for more efficient use of heavy oil residues. Taken together, the results provide valuable insight into the intricacies of producing low-sulfur coke from heavy petroleum residues. In addition to industrial significance, this research also has environmental significance, since it proposes an approach that allows not only to maximize the use of secondary resources, but also to reduce the sulfur content in coke, which will help limit the environmental impact of industrial processes.