Concentrations Of Hydrocarbons Research Articles

Seasonal Variation of Groundwater Quality in Bonny Island, Rivers State Nigeria

This study investigated the seasonal variations in physicochemical parameters, heavy metals, and petroleum hydrocarbons in groundwater samples collected in nine locations in Bonny Island, Rivers State Nigeria. The water samples for the dry season were collected in December and January while for the wet season, water samples were collected in July and October. A quantitative approach was employed, involving the collection of quantitative data through field sampling and laboratory analysis. Physicochemical parameters, including pH, electrical conductivity, dissolved oxygen, and nutrient levels, were measured using standard analytical techniques. Heavy metal concentrations (Fe, Cd, etc.) were determined using atomic absorption spectrophotometry, while petroleum hydrocarbons (total hydrocarbons and polycyclic aromatic hydrocarbons) were analyzed through solvent extraction and gas chromatography techniques. The study revealed significant seasonal variations in several parameters, with notable significant decreases in phosphate during the wet season and significant increases in chromium and cadmium levels during the dry season (p-value < 0.05). Petroleum hydrocarbon concentrations also exhibited seasonal fluctuations, potentially influenced by precipitation patterns, oil and gas activities, and accidental spills or leaks which were observed during the dry season.

Enhanced catalytic activity of Sm/CeO2 to produce gasoline-range hydrocarbons from pyrolysis of spent coffee grounds

This study investigated the application of Sm/CeO2 catalyst for hydrocarbon production in catalytic pyrolysis (CP) of spent coffee grounds (SCGs). A temperature range of 450–750 °C and catalyst/biomass (C/B) ratios of 0.5–4 were employed in the CP. The results showed that an increase in pyrolysis temperature consistently increased the quantity of hydrocarbons and considerably decreased the oxygenated compounds like acids and phenols. At temperatures of 450 and 550 °C, C/B ratios of 2 or 1 generated the maximum amount of hydrocarbons. At 650 and 750 °C temperatures, C/B ratios of 0.5 and 1 were capable to achieve a higher content of hydrocarbons in bio-oils, suggesting the synergistic effect of temperature and catalyst activity. The hydrocarbons in bio-oils were found in the gasoline range, mainly containing benzene, toluene, ethylbenzene, xylene (BTEX), olefins, and cycloalkenes. Primary reactions involved to convert oxygenated compounds into hydrocarbons were dehydration, decarboxylation, decarbonylation, dehydrogenation, isomerization, and aromatization reactions.

Insights into bacterial diversity in industrial post-processing water from underground coal gasification (UCG) process

This study represents the first culture-independent profiling of microbial diversity in post-processing wastewater from underground coal gasification (UCG) processes. Three types of post-processing wastewater, named W1, W2 and W3, were obtained from three UCG processes involving two types of coal and two gasification agents, namely oxygen-enriched air and oxygen. Very high concentrations of BTEX (benzene, toluene, ethylbenzene, xylene), polyaromatic hydrocarbons (PAHs), and phenol were detected in the wastewater, classifying it into the fifth toxicity class, indicating very high acute toxicity. The values for the Shannon (H), Ace and Chao1 indices in W2 were the lowest compared to their values in W1 and W3. The dominate phyla were Proteobacteria, contributing 84.64% and 77.92% in W1 and W3, respectively, while Firmicutes dominated in W2 with a contribution of 66.85%. At the class level, Gammaproteobacteria and Alphaproteobacteria were predominant in W1 and W3, while Bacilli and Actinobacteria were predominant in W2. Among Bacilli, the Paenibacillus and Bacillus genera were the most numerous. Our results suggest that the main differentiating factor of the bacterial structure and diversity in the wastewater could be the gasification agent. These findings provide new insights into the shifting patterns of dominant bacteria in post-processing wastewater and illustrate the spread of bacteria in industrial contaminated wastewater.

STUDY OF THE DYNAMICS OF THE PROCESS OF ADSORPTION OF AROMATIC HYDROCARBONS FROM ALKANE

In petrochemistry, normal paraffins are used mainly as raw materials for the production of alkylbenzenes, alkanesulfonates, synthetic fatty acids, secondary alcohols, a-olefins (thermocracking), internal olefins (dehydrogenation). Currently, the market for synthetic detergents (SMC) is one of the most dynamically developing in the world. According to the forecasts of the leading companies producing alkyl benzenes, in the next 10 years, the demand for intermediates for the production of synthetic detergents is expected to grow both in domestic markets and in the global market as a whole. At hydrotreatment units, a wide fraction of n-paraffins (C9–C20) is released from hydrotreated diesel fuel. After that, the C9–C20 fraction is sent to the pre-fractionation unit of the olefin production unit, where the C14–C17 fraction is separated from the wide fraction. This fraction is marketable and requires preliminary purification from aromatic hydrocarbons. Typically, the content of aromatic hydrocarbons in the crude fraction С14+ is from 0.5 to 2.0 wt%. The residual content of aromatic hydrocarbons in the purified fraction should not exceed 0.01% wt. To remove aromatic hydrocarbons, the С14+ fraction is fed to the oleum treatment unit. At the oleum purification unit, post-treatment is carried out using oleum with a concentration of 20–24% wt. After sulfonation, it is necessary to neutralize with caustic soda. Obtaining dearomatized liquid paraffins from diesel fuel using oleum purification has many disadvantages, since working with fuming sulfuric acid requires a high degree of protection of the human body and the strictest observance of safety regulations. Due to the difficulties in disposing of spent sulfuric acid, plant shutdowns and downtime are not uncommon. This article presents the results of a comprehensive study of the adsorption of aromatic hydrocarbons from higher alkanes on zeolite CaX. The main parameters of statics, dynamics and kinetics of adsorption are determined

The Effect of Burning on the Polycyclic Aromatic Hydrocarbons (PAH) Content in Goat Satay in the East Java Region

The Effect of Burning on the Polycyclic Aromatic Hydrocarbons (PAH) Content in Goat Satay in the East Java Region

Understanding the dynamics of enhanced light non-aqueous phase liquids (LNAPL) remediation at a polluted site: Insights from hydrogeophysical findings and chemical evidence

This study intricately unfolds a pioneering methodology for remediating contaminants in a persistent light non-aqueous phase liquids (LNAPL)-contaminated site. The remediation strategy seamlessly integrates enhanced desorption and in-situ chemical oxidation (ISCO), orchestrating the injection of PetroCleanze® (a desorbent) and RegenOx® (an oxidizer) through meticulously designed wells. These injections, based on detailed geological and hydrogeological assessments, aim at mobilizing residual contaminants for subsequent extraction. Real-time subsurface dynamics are investigated through geophysical monitoring, employing electrical resistivity tomography (ERT) to trace reagent migration pathways via their effect on bulk electrical conductivity. The integration of groundwater sampling data aims at providing additional insights into the transformations of contaminants in the spatiotemporal context. Vivid two-dimensional time-lapse ERT sections showcase the evolution of resistivity anomalies, providing high-resolution evidence of the heterogeneity, dispersion pathways of desorbent and oxidant, and residual LNAPL mobilization. Hydrochemical analyses complement this, revealing effective mobilization processes with increasing aqueous concentrations of total petroleum hydrocarbons (TPH) over time. Speciation analysis unveils the intricate interplay of desorption and oxidation, portraying the dynamic fractionation of hydrocarbon components. The hydrogeophysical and data-driven framework not only delivers qualitative and quantitative insights into reagent and contaminant distribution but also enhances understanding of spatial and temporal physio-chemical changes during the remediation process. Time-lapse ERT visually narrates the reagent's journey through time, while chemical analyses depict the unfolding processes of desorption and oxidation across space and time. The coupling of hydrogeophysical and chemical findings pictures the transformations of pollutants following the sequence of product injection and the push and pull activities, capturing the removal of mobilized contaminants through hydraulic barrier wells. This enhanced understanding proves instrumental towards optimizing and tailoring remediation efforts, especially in heterogeneous environmental settings. This study establishes a new standard for a sophisticated and innovative contaminant remediation approach, advancing environmental practices through the harmonized analysis of geophysical and chemical data.

Toward better atmospheric polycyclic aromatic hydrocarbons pollution control in the Northern Hemisphere: Process analysis based on interpretable deep learning models

The accurate prediction of atmospheric polycyclic aromatic hydrocarbons (PAHs) concentrations in the Arctic is crucial in guiding the development of pollution control measures for atmospheric PAHs. However, the complex formation process and strong time-dependence of PAHs in the Arctic increase the difficulty of prediction. Herein, deep learning (DL) models were developed to predict monthly air concentrations of 16 priority PAHs at Alert monitoring station by incorporating the inherent periodicity of PAH concentrations and ancillary data including PAH emissions, meteorological information, fire emissions, and sea ice area. The prediction performance of long short-term memory (LSTM), gated recurrent unit (GRU) and bidirectional LSTM (Bi LSTM) algorithms were compared by multiple model evaluation metrics. The results showed that Bi LSTM models outperformed LSTM and GRU in predicting PAHs concentrations because it exhibited higher accuracy in terms of average R2ext (0.09) and errors (average MAPEext = 1.45). The DL interpretation based on SHAP values suggested that the main drivers of PAHs concentrations were PAHs emissions and sea ice area, with a more prominent contribution from meteorological conditions. The interpretable deep learning approach provides a potential shortcut for predicting time-delayed PAHs concentrations in the Arctic, promoting the management and control of global PAHs pollution.

Chemical composition and biological activities of essential oils of seven Cultivated Apiaceae species

The Apiaceae family contains many species used as food, spice and medicinal purposes. Different parts of plants including seeds could be used to obtain essential (EO) oils from members of the Apiaceae family. In the present study, EOs were components obtained through hydrodistillation from the seeds of anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), dill (Anethum graveolens), coriander (Coriandrum sativum), fennel (Foeniculum vulgare), and cumin (Cuminum cyminum). EO constituents were determined with Gas Chromatography/Mass Spectrometry (GC–MS) and Gas Chromatography/Flame Ionization Detector (GC-FID) and their antioxidant capacities were determined with the cupric reducing antioxidant capacity (CUPRAC) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) methods. The antimicrobial activity of EOs were tested against four pathogenic bacteria. Phenylpropanoids in anise (94.87%) and fennel (92.52%), oxygenated monoterpenes in dill (67.59%) and coriander (98.96%), monoterpene hydrocarbons in celery (75.42%), mono- (45.42%) and sesquiterpene- (43.25%) hydrocarbons in carrots, monoterpene hydrocarbon (34.30%) and aromatic hydrocarbons (32.92%) in cumin were the major compounds in the EOs. Anethole in anise and fennel, carotol in carrot, limonene in celery, carvone in dill, linalool in coriander, and cumin aldehyde in cumin were predominant compounds in these EOs. The high hydrocarbon content in cumin EO gave high CUPRAC activity (89.07 µmol Trolox g−1), and the moderate monoterpene hydrocarbon and oxygenated monoterpene content in dill EO resulted in higher DPPH activity (9.86 µmol Trolox g−1). The in vitro antibacterial activity of EOs against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was evaluated using the agar diffusion method and the minimum bactericidal concentration was determined. Coriander, cumin and dill EOs showed inhibitory effect against all tested strains except P. aeruginosa. While fennel and celery EOs were effective against E. coli and B. cereus strains, respectively, anise and carrot EOs did not show any antibacterial effect against the tested bacteria. Hierarchical Cluster Analysis (HCA) produced four groups based on EO constituents of seven species. The potential adoption of the cultivated Apiaceae species for EO extraction could be beneficial for the wild species that are endangered by over collection and consumption.

Investigations for Soil Contamination with Hydrocarbon Compounds near Oil Stations

Field companies are subject to many standards to preserve the environment. Oil companies are considered among the companies that cause the most environmental pollution for two reasons: the first is the extraction of large quantities of crude oil, and the second is their violation of the controls imposed on them. In this research the investigations on the nearby and around a Rumaila oil station area were abducted scientifically through a real tested sample. In this research, investigations in an area near and around the Rumaila Oil Station were conducted scientifically through real laboratory samples. An analysis was made to determine the total petroleum hydrocarbons (TPH), where 22 samples were collected, as well as 5 laboratory samples of soil from an unpolluted area, and crude oil was added to it in known proportions to determine the spectral signature. The ASD Field spec 3 device was used to record the spectral signatures of each sample. Areas sensitive to hydrocarbons 17050 and 1350 appeared. The results show a variation in the concentrations of hydrocarbon in the samples from (2 ppm) at the minimum and reach (197 ppm) at other locations around the station.

The effectiveness of soil washing as a remediation method on oil spill contaminated soil (Case Study: Wonocolo Traditional Oil Mine)

The exploitation of petroleum in Wonocolo is conducted with traditional equipment, leading to contamination by oil spills. Oil Spill contamination has the potential damage to ecological, soil, and surface water, caused by the hydrocarbon content itself. Total Petroleum Hydrocarbon (TPH) test results on contaminated soil show the highest value at 17.4%. Experiments were carried out to analyze the effectiveness of soil washing using Alky Benzene Sulfonate surfactants to reduce the TPH number. Experiments are conducted with variations in surfactant concentrations such as 0%, 0.25%, 0.50%, 0.75%, and 1%. The results of the Soil Washing experiment showed that the surfactant concentration with the highest effectiveness was at a concentration of 0.25%. Concentration of 0.25% reduces TPH by 9% with 51.72% effectiveness.

Soil column-experimental research on the migration pattern of petroleum pollutant in the soil

In the process of oilfield exploitation and production, harmful pollutants, such as Crude oil that falls to the ground (generally refers to crude oil that leaks to the ground during oil production or transportation), production wastewater and oil-bearing mud are produced. In this contribution, the soil and crude oil from Daqing area are adopted as experimental materials to make a soil column-experimental device. The results show that the maximum migration depth of petroleum pollutants is 25 cm, most of the pollutants exist above 10 cm. The components of pollutants in disturbed soil column are complex, and the peak area of each component is large, mainly distributed in C12–C28, while in undisturbed soil column, the content of pollutants is small, and the peak area of each component is also small, mainly distributed in C12–C22. With the increase of depth, the relative content of aromatic hydrocarbons increases. The migration ability of low carbon component is weaker than the other components in crude oil. The components with high carbon number are significantly higher in shallow part. The relative contents of each component from high to low are saturates, aromatic hydrocarbons, resin and asphaltene in the soil. Compared with disturbed soil columns, the structure of undisturbed soil is complex, and the migration rate of pollutants in undisturbed soil is slower than that in disturbed soil. With the increase of depth, the light components of disturbed soil columns gradually decrease, and the relative content of heavy components changes little. The light components of the undisturbed soil column also gradually decreased, and the heavy components greater than C22 did not migrate to the depth of the soil column.

Structure and composition of microbial communities in the water column from Southern Gulf of Mexico and detection of putative hydrocarbon-degrading microorganisms.

This study assessed the bacterioplankton community and its relationship with environmental variables, including total petroleum hydrocarbon (TPH) concentration, in the Yucatan shelf area of the Southern Gulf of Mexico. Beta diversity analyses based on 16S rRNA sequences indicated variations in the bacterioplankton community structure among sampling sites. PERMANOVA indicated that these variations could be mainly related to changes in depth (5 to 180 m), dissolved oxygen concentration (2.06 to 5.93 mg L-1), and chlorophyll-a concentration (0.184 to 7.65 mg m3). Moreover, SIMPER and one-way ANOVA analyses showed that the shifts in the relative abundances of Synechococcus and Prochlorococcus were related to changes in microbial community composition and chlorophyll-a values. Despite the low TPH content measured in the studied sites (0.01 to 0.86 μL L-1), putative hydrocarbon-degrading bacteria such as Alteromonas, Acinetobacter, Balneola, Erythrobacter, Oleibacter, Roseibacillus, and the MWH-UniP1 aquatic group were detected. The relatively high copy number of the alkB gene detected in the water column by qPCR and the enrichment of hydrocarbon-degrading bacteria obtained during lab crude oil tests exhibited the potential of bacterioplankton communities from the Yucatan shelf to respond to potential hydrocarbon impacts in this important area of the Gulf Mexico.

Total Petroleum Hydrocarbons in Soil of Different Oil Fields at Basrah Governorate, Iraq

Objectives: This study concentrated on determining the total hydrocarbon concentrations in soil at eleven stations of the oil field (Seba, Safwan, Majnoon, Ratawi, Bergezia, Qurna2, Qurna1, Shuaaba, South and North Rumaila, and Al Zubair). Methods: Soil samples were freeze-dried, finely pulverised in an agate mortar, and sieved through a 62-um metal sieve and 150 ml mixture of methanol and benzene (1:1) was used to extract the soil. Determination of TPHs where determined by using Spectrofluroscence, Total organic carbons (TOC) in the soil of the oil fields were also determined. Results: According to the TPH distribution used in this investigation, station 11 (Al Zubair) had the highest concentration of TPHs (162.53mg/g dry weight), while station 1(Seba) had the lowest concentration (21.4mg/g dry weigh). Additionally, the study's findings demonstrated that TPH levels varied spatially amongst sites. The highest amounts of total petroleum hydrocarbons detected in soil samples, as well as the findings of this investigation indicating that TPH levels varied geographically throughout stations. Conclusions: There is significant correlation between the TPH in soil and TOC%. By comprising the result concentration of this study with literature reviews, the concentration levels lies within it and in other cases exceed it.

Eutrophication in cold-arid lakes: molecular characteristics and transformation mechanism of DOM under microbial action at the ice-water interface

During freezing periods, nutrients (carbon and organic matter, etc.) are enriched in the water and sediment of lakes in cold-arid regions, leading to potential algal bloom outbreaks and other health risks to the ecosystem. Particularly, dissolved organic matter (DOM) is a critical component of the nutrients and plays an important role in the global carbon cycle. However, the mechanisms of DOM transfer between ice and water remain unclear. This study analyzed the influence of microbial community on DOM composition using 16 s RNA, 3DEEM, and FT-ICR MS in Daihai Lake and Wuliangsuhai Lake in the Yellow River Basin, China. According to the spectral analysis, the content of endogenous organic matter, such as humus, accounted for 40% of the total DOM in water, while the content of tryptophan and tyrosine accounted for 80% of the total DOM in ice. The results of mass spectrometry showed that lignin was the main component, and the content of organic matter in the ice was less than that in the water. Molecular structures of seven DOM coexisting in the lake ice and water were elucidated with adapted Kendrick-analogous network visualization, which clearly illustrates that long-chain DOM molecules are derived from small molecules, while other heteroatoms are complexed with the side groups. The positive correlations between CHO, CHNO, CHOS, CHOS and Actinomyces indicate that DOM actively interacted with the microbial community. 44% of CHO compounds have the same molecular formula in water, the content of CHOS in the water of the two lakes was closed to 7% higher than that in the ice. Meanwhile, DOM dynamically migrate between ice and water via interstitial water because of the solubility changes under microbial transformation, which has been proved by the decrease in the contents of the humus and tryptophan-like substances in the ice from the bottom to the surface and lower contents of carbohydrate and unsaturated aromatic hydrocarbon in the water than the ice. This study helps to predict the composition and structure of DOM during the migration in lakes and provides a scientific basis for environmental remediation with high concentration of carbon.

Diagnosis of Crude Oil Impacted Soil in Eleme Local Government Area, Rivers State, Nigeria

This study assessed the potential effects of crude oil on soil quality in Eleme Local Government Area of Rivers State. Soil samples were collected from 10 geopolitical wards of the Eleme Local Government Area of Rivers State, Nigeria. The soil and water samples were subjected to physicochemical and microbial analyses to test for pH, heavy metal content (Cadmium, Iron, Lead, Copper, and Chromium), Total Petroleum Hydrocarbon (TPH), Benzene, Toluene, Ethylbenzene and Xylene (BTEX) contents and Total Viable Count (TVC). Parameters of the soil were determined and compared to the control site and the permissible World Health Organization (WHO) limits. The soil pH varied across location, ranging from 5.5-7. TPH varied in across the different communities studied, ranging from 1.275-4889.29 mg/kg, and exceeding the WHO limit of 10mg/kg in all polluted soils. The result for the heavy metals showed that the soil samples of the studied sites showed increases in all heavy metals, when compared to the control. Cd values ranged from 0.01 - 0.32 mg/kg; Fe from 1325.23 - 9364.76 mg/kg, Pb from 0.001 mg/kg to 0.93 mg/kg and Cr from 0.001 - 5.08 mg/kg, all with WHO limits. The result for the microbial showed increases in TVC content in polluted soil. Results indicate that crude oil spillage has led to significant contamination of soil in the study area which could affect soil fertility.

Occurrence and characteristics of PAHs in coastal seawater off the city of Samsun on the Black Sea coast of Turkey

Polycyclic aromatic hydrocarbons (PAHs) concentrations in seawater were monitored seasonally along the Samsun coast, Turkey, between August 2019 and May 2020 to elucidate main origin, seasonal variations, and risk pathways of PAHs. Total PAH concentrations in surface seawater ranged from 24.86 to 477.78 ng L−1 (mean 138.90, SD 62.22 ng L−1), with relatively higher levels in summer and autumn seasons. Combustion products were the major sources of PAHs. The increased PAH levels during the summer period may have resulted from the more intense industrial and agricultural activities. The highest proportion of PAHs were 3- and 2-ringed, accounting for 39.23 % and 26.50 % of ΣPAHs, respectively, and their derivatives Nap and Phe predominated in individual PAHs. While RQ values of ∑PAHs showed low ecological risk, RQMPCs of BpF and BaA in autumn and BpF in summer were at high ecological risk.

Phytochemical profiling, antidiabetic, antiobesity, and antibacterial activities of Cometes abyssinica

This study aims to complete my chemical and biological studies on Cometes abyssinica (CA). The chemical profile was reported by LC-ESI-TOF-MS and GC-MS analyses. Antidiabetic (α-Glucosidase and a-amylase inhibitory activity assay), antiobesity (Lipase inhibitory activity assay), and antibacterial activity (agar well diffusion assay) were determined. The GC-MS analysis led to the identification of 27 hydrocarbons representing 93.4% of the total hydrocarbon content in hexane extract. 11-Octadecenoic acid, methyl ester (28.07%), citronellol (9.31%), hexadecanoic acid, methyl ester (7.64%), phytol (5.93%), and 10-epi-γ-eudesmol (4.91%) were the major components. The LC-ESI-TOF-MS analyses of aqueous-methanolic extract led to the identification of 99 secondary metabolites including phenolics, flavonoids, alkaloids, and vitamins. The percentages of inhibition of the n-hexane, chloroform, ethyl acetate, and methanol extracts of CA were evaluated against α-glucosidase, α-amylase, and pancreatic lipase enzymes at different concentrations. Hexane extract showed the most powerful α-glucosidase and α-amylase inhibitory activity with IC50 value of 0.22 and 0.27 mg/ml comparing with acarbose (IC50 0.43 and 0.38), respectively. Among all CA extracts, only ethyl acetate extract revealed potent antiobesity as a lipase inhibitory activity with IC50 value of 0.079 mg/ml comparing with orlistat (IC50 0.11 mg/ml). CA extracts showed mild-weak antibacterial effect against Pseudomonas aeruginosa and Bacillus cereus. KEY WORDS: Cometes abyssinica, Chemical constituents, α-Amylase inhibitors, α-Glucosidase inhibitors, Lipase inhibitors Bull. Chem. Soc. Ethiop. 2024, 38(4), 1051-1067. DOI: https://dx.doi.org/10.4314/bcse.v38i4.19

Gasification of Liquid Hydrocarbon Waste by the Ultra-Superheated Mixture of Steam and Carbon Dioxide: A Thermodynamic Study

The thermodynamic modeling of waste oil (WO) gasification by a high-temperature gasification agent (GA) composed of an ultra-superheated H2O/CO2 mixture is carried out. The GA is assumed to be obtained by the gaseous detonation of fuel–oxidizer–diluent mixture in a pulsed detonation gun (PDG). N-hexadecane is used as a WO surrogate. Methane or the produced syngas (generally a mixture of H2, CO, CH4, CO2, etc.) is used as fuel for the PDG. Oxygen, air, or oxygen-enriched air are used as oxidizers for the PDG. Low-temperature steam is used as a diluent gas. The gasification process is assumed to proceed in a flow-through gasifier at atmospheric pressure. It is shown that the use of the detonation products of the stoichiometric methane–oxygen and methane–air mixtures theoretically leads to the complete conversion of WO into a syngas consisting exclusively of H2 and CO, or into energy gas with high contents of CH4 and C2-C3 hydrocarbons and an LHV of 36.7 (fuel–oxygen mixture) and 13.6 MJ/kg (fuel–air mixture). The use of the detonation products of the stoichiometric mixture of the produced syngas with oxygen or with oxygen-enriched air also allows theoretically achieving the complete conversion of WO into syngas consisting exclusively of H2 and CO. About 33% of the produced syngas mixed with oxygen can be theoretically used for PDG self-feeding, thus making the gasification technology very attractive and cost-effective. To self-feed the PDG with the mixture of the produced syngas with air, it is necessary to increase the backpressure in the gasifier and/or enrich the air with oxygen. The addition of low-temperature steam to the fuel–oxygen mixture in the PDG allows controlling the H2/CO ratio in the produced syngas from 1.3 to 3.4.

The effectiveness of various biochar types in enhancing the phytoremediation of soils polluted with petroleum hydrocarbon

AbstractBackgroundBiochar can enhance phytoremediation in petroleum hydrocarbon polluted soils, making it an intriguing soil amendment option for remediating polluted soil. Biochar can improve the fertility of depleted soils through a range of mechanisms. This study can contribute valuable insights into the origin of biochar and enhance our understanding of the efficacy of different biochar types in remediating petroleum hydrocarbon polluted soils.AimsTo assess the efficacy of different biochar types and plant growth in remediating petroleum hydrocarbon polluted soils.MethodsA field experiment was conducted at the automobile workshop (commonly called mechanic village) from July to October 2021, using a randomized complete block design. The land was sectioned into designated plots with three replicates. Maize stalk biochar (MSB) and nipa palm biochar (NPB) were treated differently in each plot at a rate of 20 t ha−1. Plots containing no biochar were used as controls. Initial and final soil analyses were conducted.ResultsPreliminary soil assessments revealed higher values of soil bulk density (1.51 g cm−3), moisture content (35.02%), organic carbon (41.01 g kg−1), cation exchange capacity (13.27 cmol kg−1), total petroleum hydrocarbon content (PHCt) (775.83 mg kg−1), cadmium (Cd) (5.41 mg kg−1), chromium (Cr) (25 mg kg−1), lead (Pb) (33.51 mg kg−1), and zinc (Zn) (0.91 mg kg−1) in the polluted soil than in the unpolluted counterpart. The polluted soil displayed lower hydraulic conductivity (Ks) (1.17 cm h−1), available phosphorus (69.46 mg kg−1), manganese (Mn) (6.38 mg kg−1) and iron (Fe) (4.18 mg kg−1) contents than the unpolluted soil. The PHCt, Cd, and Cr were significantly decreased following the application of biochar. NPB recorded the lowest petroleum hydrocarbon (19%), lead (37%), manganese (57%), and zinc (69%) contents, whereas MSB had the lowest cadmium (50%) and chromium (27%) contents when compared with the control. Between heavy metal accumulations in the leaves and fruits, a greater accumulation of Cd, Cr, and Pb was found in the leaves, whereas Ni accumulation was found in the fruits. The highest Cd (47.0 mg kg−1) and Ni (8.3 mg kg−1) accumulations in the leaves were recorded in NPB treated plots. Similarly, Cd (5.3 mg kg−1), Cr (3.7 mg kg−1), Pb (21.6 mg kg−1), and Ni (23.4 mg kg−1) accumulation in the fruits recorded the highest values in the NPB treated plots. The NPB plants were the tallest compared with the other treatments. In addition, NPB plants had the widest leaf area compared with other treatments.ConclusionThe results indicated that the amendment of NPB may be suitable for the phytoremediation of soils polluted with petroleum hydrocarbons.

Performance of Transition Metal Supported Al2O3 Coated on Honeycomb Catalysts and Its Segmentation on Exhaust Gasses Oxidation

The oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) under segmented honeycomb catalysts was investigated using actual exhaust gas mixtures from a gasoline-fueled internal combustion engine of a motorcycle. The honeycomb catalysts were prepared through a wet process, resulting in four types coated with transition metals (Cu, Cr, Fe, and Ni) supported on Al2O3. The oxidation of CO and HC was monitored using an exhaust gas analyzer across a range of air-to-fuel ratios (AFR), from lean to rich, under stationary conditions. The results demonstrate that the honeycomb catalysts effectively decreased CO and HC concentrations in the exhaust gas. Among the transition metal oxide honeycomb catalysts, Cr and Ni exhibited high CO and HC conversion rates, surpassing those observed with Cu. The average CO and HC conversion calculations, spanning from lean to rich air-to-fuel ratios, were consistent with the actual conversion rates achieved. Furthermore, the study investigated the effect of honeycomb segmentation on CO and HC conversion. Surprisingly, the catalytic performance of Cr and Ni remained high even with longer gaps in the honeycomb. Interestingly, the conversion of CO and HC over the iron oxide honeycomb catalyst increased as the gap in the honeycomb became longer. This is likely due to an increase in the gap size and enhanced re-mixing of reactants (CO, HC, and O2) caused by recirculation. Thus, this study provides valuable elucidation on the potential application of segmented honeycomb catalysts for reducing CO and HC emissions in exhaust gases.