Diesel Additives Research Articles

An Experimental Study using Diesel Additives to Examine the Combustion and Exhaust Emissions of CI Engines

An Experimental Study using Diesel Additives to Examine the Combustion and Exhaust Emissions of CI Engines

The Impact of Incorporating Varying Proportions of Sugar Beet Waste on the Combustion Process and Emissions in Industrial Burner Fuelled with Conventional Diesel Fuel

Abstract The main objective of the case study is to investigate the effectiveness of using solid fuel additives in conventional diesel fuel for industrial furnaces. The study focuses on utilizing agricultural waste derived from sugar beet plant waste as additives to enhance the combustion process and reduce emissions from industrial burners. In this study, experimental measurent for the flame temperatures inside the furnace while altering the proportions of the solid materials have ben achived. The goal was to assess the impact of different loading from these additives on the combustionprocess. Furthermore, the study involved measuring exhaust gases such as carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbon (UH), and nitrogen oxides (NOx). The experimental facility arranment allowed the researchers to evaluate the emissions resulting from the combustion process with the addition of solid fuel additives. By measuring these parameters, the study aimed to understand the effect of utilizing agricultural waste as additives on the burning processes and emission formation in industrial furnaces. These findings can contribute to improving the efficiency of combustion processes, reducing emissions, and promoting the utilization of renewable and sustainable fuel sources in industrial settings. In this study, varying the proportions of solid materials used as additives had an impact on the levels of carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOx) in the exhaust gases. By increasing the proportion of solid materials in the fuel mixture resulted in changes in the emission levels. The levels of carbon monoxide in the exhaust gases decreased as the proportion of solid materials increased. While the addition of solid fuel additives did contribute to the production of CO2 due to the combustion of the additives, the overall effect on its levels varied depending on the specific proportions used. Also, the levels of nitrogen oxides in the exhaust gases showed different trends depending on the proportions of solid materials used. Typically, increasing the proportion of solid fuel additives led to reduce NOx emissions. However, this may also depend on other factors such as combustion temperature and the composition of the solid materials.

Tandem hydroformylation-amine condensation and reduction of canola fatty acid methyl esters for production of diesel renewable antioxidant additives

A canola fatty acid methyl esters (FAME) mixture was synthesized through transesterification and modified by rhodium homogeneous tandem hydroformylation-amine condensation, with primary amines, yielding imine products. The obtained imines were reduced by maceration with sodium borohydride and alumina, yielding secondary amine products. The synthesized fatty imines and amines were evaluated as additives for commercial diesel and biodiesel on concentrations of 0.5 and 1.0 %, while tested for oxidative stability fallowing the EN14112 standard method. The tested amino products exhibited higher oxidative stability, which justifies its application as antioxidant additives, while the diesel blends did not show expressive physicochemical modifications. The modified amino-FAME antioxidant performance, justifies a renewable biorefinery application, extend the biodiesel shelf-life prior to diesel blending, complies with UN’s Sustainable Development Goals (SDGs) and if prepared from residues, enhance the circular economy appeal.

Assessment of C-Band Polarimetric Radar for the Detection of Diesel Fuel in Newly Formed Sea Ice

There is a heightened risk of an oil spill occurring in the Arctic, as climate change driven sea ice loss permits an increase in Arctic marine transportation. The ability to detect an oil spill and monitor its progression is key to enacting an effective response. Microwave scatterometer systems may be used detect changes in sea ice thermodynamic and physical properties, so we examined the potential of C-band polarimetric radar for detecting diesel fuel beneath a thin sea ice layer. Sea ice physical properties, including thickness, temperature, and salinity, were measured before and after diesel addition beneath the ice. Time-series polarimetric C-band scatterometer measurements monitored the sea ice evolution and diesel migration to the sea ice surface. We characterized the temporal evolution of the diesel-contaminated seawater and sea ice by monitoring the normalized radar cross section (NRCS) and polarimetric parameters (conformity coefficient (μ), copolarization correlation coefficient (ρco)) at 20° and 25° incidence angles. We delineated three stages, with distinct NRCS and polarimetric results, which could be connected to the thermophysical state and the presence of diesel on the surface. Stage 1 described the initial formation of sea ice, while in Stage 2, we injected 20L of diesel beneath the sea ice. No immediate response was noted in the radar measurements. With the emergence of diesel on the sea ice surface, denoted by Stage 3, the NRCS dropped substantially. The largest response was for VV and HH polarizations at 20° incidence angle. Physical sampling indicated that diesel emerged to the surface of the sea ice and trended towards the tub edge and the polarimetric scatterometer was sensitive to these physical changes. This study contributes to a greater understanding of how C-band frequencies can be used to monitor oil products in the Arctic and act as a baseline for the interpretation of satellite data. Additionally, these findings will assist in the development of standards for oil and diesel fuel detection in the Canadian Arctic in association with the Canadian Standards Association Group.

Experimental evaluation of a diesel engine using amide-functionalized carbon nanotubes as additives in commercial diesel and palm-oil biodiesel

Nanomaterials used as additives to diesel, biodiesel, and its blends have shown promising results in improving thermal efficiency and reducing pollutant emissions in compression ignition engines. However, the stability of dispersions has been noted in the literature as a primary challenge to the effective use of nanomaterials as fuel additives. Between nanomaterials used as additives to fuels are carbon nanotubes (CNTs). These carbonaceous materials have shown positive and negative results concerning engine performance and emissions, and the differences could be associated with the dispersion stability of the nanomaterials in the fuel. Therefore, there is still much uncertainty regarding the relationship between the stability of nanomaterial dispersion and the impact of nanofuels on engine performance. Specifically, the current literature lacks sufficient information regarding the impact of incorporating amide-functionalized carbon nanotubes (CNT) on the stability of diesel-biodiesel blends and their influence on particulate matter emissions in ICE. In this study CNT and amide-functionalized CNT were dispersed in Colombian commercial diesel (10 % vol. of palm oil biodiesel) and palm oil biodiesel, and its stability was evaluated. The most stable blends were used in a stationary Ignition Compression Engine (ICE) to evaluate the impact of the nanomaterials on thermal efficiency and pollutant emissions. Results show that it was not possible to disperse CNT in Colombian commercial diesel (10 % vol. of palm oil biodiesel and 90 % vol. of petroleum diesel) due to its high rate of agglomeration and sedimentation. In contrast, the opposite behavior was shown using biodiesel as a base fuel. An amide functionalization of the CNT process was carried out to generate a repulsion of CNT and improve its stability in commercial diesel fuel. Amide-functionalized carbon nanotubes (CNTF) were obtained using pristine CNT and Oleylamine as nitrogen functional group precursors. X-ray Photoelectron Spectroscopy confirmed the amide functional groups on the CNT surface, and a loss weight of 14 % was identified in the temperature range of 150–550 °C, indicating a high grade of functionalization. Functionalized and non-functionalized CNT were dispersed in Colombian commercial diesel and palm oil biodiesel using a concentration of 100 mg/L to evaluate the dispersion's colloidal stability. This stability was examined for three days by visual inspection and variation of the hydrodynamic diameter using dynamic light scattering. The most stable dispersions were prepared at two concentrations (50 and 100 mg/L) and used as fuels in a stationary compression ignition engine. Colloidal stability was enhanced when CNTF were dispersed in diesel compared to the unstable, pristine CNT dispersion. However, in biodiesel, the dispersion behavior of the CNT and CNTF was similar. Compared to diesel, the diesel-CNTF dispersion did not considerably improve the engine´s thermal performance at 6 kW, and only a minor gain was observed at 12 kW at a concentration of 100 mg/L. However, at 6 kW, they reduced particulate matter emissions by up to 39.8 %. In the case of biodiesel, utilizing both functionalized and non-functionalized carbon nanotubes as additives, the thermal efficiency was increased, and CO emissions decreased.

Experimental investigation of effects of tertiary fuel on carbon deposition and emissions level of compression ignition engine

This study investigates the effect of increasing urbanization on the demand for petroleum products, which are limited natural resources. The study evaluated the use of biodiesel and clove oil as additives in diesel fuel to reduce carbon deposition on engine parts and noise emissions. Three fuel samples were tested: B30 (30 % biodiesel and 70 % diesel), clove oil at 3000 parts per million (PPM), and D100 diesel fuel. Endurance tests were conducted at a constant load and revolution per minute (RPM) to analyze carbon deposition on engine parts as well as noise emission levels at constant and variable RPM. It was found that biodiesel blended fuel had higher carbon deposition formation compared to diesel fuel, with a deposition rate of 77.48 % for B30 and 71.84 % for D100. In contrast, when clove oil was added to biodiesel, engine part deposition was decreased compared to diesel fuel, with a deposition rate of 47.71 % for clove oil. Furthermore, the study analyzed noise emissions at four positions (left, right, back, and top) using the three fuel samples. Clove oil showed lower noise emissions compared to diesel, indicating that it can help reduce noise pollution.

Density, Viscosity, and Distillation Temperatures of Binary Blends of Diesel Fuel Mixed with Oxygenated Components at Different Temperatures

This paper reports density, kinematic viscosity, and distillation curves for blends of diesel fuel with n-butanol, diesel fuel with n-pentanol, and diesel fuel with diethylene glycol dimethyl ether. It is known that these properties affect not only fuel transportation and distribution processes but also the phenomena that occur in an internal combustion engine; therefore, these aspects are intriguing to study. Oxygenated compounds such as n-butanol, n-pentanol, and diethylene glycol dimethyl ether can be used as additives for diesel fuel. Their use can contribute to a significant improvement in the fuel’s ignitability due to their high oxygen contents. Measurements of the experimental properties of various blend compositions were carried out at temperatures ranging between 288.15 K and 323.15 K. Based on density and viscosity data, different mathematical models were verified for the purpose of establishing better quality standards for the production of fuel. Good accuracies were obtained in the cases of density, viscosity, and interaction parameters, with the largest average absolute deviation (AAD%) being 0.4351. Moreover, as the determination of density is uncomplicated, rapid, and requires small sample volumes, correlations with the distillation temperatures used for the fuel blends were investigated to estimate the samples’ cetane indices. These determinations will be useful in the automobile industry when designing transport equipment or pipelines in situations when oxygenated compounds may constitute a fuel component in diesel blends.

Effect of tri-ethylene glycol mono methyl ether and alumina additives on ignition delay in a hydrogen fuelled dual-fuel diesel engine

The diesel engine process including fuel injection, fuel spray, air and fuel mixing, ignition and combustion which influences its performance and emission characteristics. The fuel injection and fuel spray are important process as they are directly related to the quality of fuel which results into fluctuating the ignition and combustion characteristics. Ignition in a diesel engine occurs at the edge of the spray depending on the in-cylinder pressure and temperature. Experiments were conducted on a modified dual-fuel diesel engine (3.5 kW power) with fuel additives, diesel and hydrogen (gaseous fuel) at a stable speed of 1500 rpm. Spray behavior and ignition delay were analyzed to determine the impact of fuel additives in neat diesel combined with hydrogen. Additionally, for dual-fuel Cases, the ignition delay correlations provided for diesel engines have been modified as per the experimental results. The injection velocity was maximized with a 15–25% hydrogen substitution range because the fuel density was reduced to a minimum, but it was decreased with the addition of fuel additives. The SMD for hydrogen with neat diesel and diesel with fuel additives both increased up to 20% hydrogen substitution, whereas for higher hydrogen substitution, the Sauter mean diameter decreased. It was found that the addition of fuel additives in diesel resulted into an increased fuel injection velocity (3.3%) with reduced sauter mean diameter of 3.4% while with the lower substitution of H2 (15%), a maximum increment of 32% in the injection velocity was seen as compared with neat diesel operation. With 15% hydrogen substitution, the change in pressure and density of diesel along with fuel additives accommodated the optimum spray penetration equivalent to neat diesel. In all Cases of hydrogen substitution, the experimental and theoretical values obtained for the chemical ignition delay were found to be consistent with one another except for 35% H2 showing a maximum deviation of 0.2%.

Investigating C3 and C4 esters and alcohols in a diesel engine: Combined influence of carbon chain length, oxyfuel type, and oxygen content

Diesel engines fueled by liquid fuels will continue to dominate the transportation and heavy machinery application market despite the advancement of other technologies. Studies have yet to be conducted to investigate the combined influence of carbon chain length, oxyfuel type, oxygen content, and blending ratio of esters and alcohols as additives in diesel fuel. The present study addresses this by preparing two sets of experiments using three-carbon (C3) and four-carbon (C4) additives, one at an equal blending ratio of 4% and the other at an equal oxygen mass content of 1.94%. Although the additives caused up to 24.84% rise in brake specific fuel consumption at low load, the value diminished to 7.86% at medium load and 11.63% at high load. The C4 fuels were found to have better NOx reduction potential than the C3 fuels. However, most additives significantly increased CO emissions, except for EE4.9 (4.9% ethyl ethanoate and 95.1% diesel), leading to 3.7% and 7.1% lower CO emissions than neat diesel at low and medium loads, respectively. Smoke emissions were also reduced by up to 32.84% when oxygenated additives were used. Although all blends tested are promising fuel alternatives in a diesel engine, EE4.9 provided the most suitable trade-off between engine performance and emissions.

Experimental and mechanism exploration on the separation of methanol-containing azeotropic compounds from biodiesel by phosphate esters ionic liquids

Abundant coal resources in China have led to an excess of methanol production. This work explores the separation strategy of dimethoxymethane-methanol (DMM-MeOH) and dimethyl carbonate (DMC)-MeOH binary azeotropes, which are easily produced in the production of diesel additives. Implementing energy-saving, emission reduction, and low carbon emission strategies is important. Three types of phosphate esters ionic liquids (ILs) with different chain lengths were prepared to realize the separation of DMM-MeOH and DMC-MeOH binary azeotrope. Based on the vapor-liquid equilibrium experiments, the vapor-liquid equilibrium data of the DMM-MeOH and DMC-MeOH binary azeotropes using phosphate esters ILs of three different chain lengths were measured at 101.3 kPa. The effect of phosphate esters ILs with three different chain lengths on the separation of DMM-MeOH and DMC-MeOH azeotropes was investigated. The separation mechanism of the azeotropes was studied at the molecular level. The electron density difference explores the optimal configuration between molecules. The atomic theory of molecules analysis directly displays the characteristics of bond critical points and explores the influence of hydrogen bond strength on the intermolecular bond length. The important roles of hydrogen bonds and steric hindrance in the separation process were investigated by reduced density gradient and independent gradient model. Quantum chemical calculation results showed that phosphate esters ILs have a significant effect on the molecular interactions of azeotropes, which is the main factor for phosphate esters ILs in reducing the relative volatility between azeotropes.

Enhancement of combustion and emission characteristics of diesel using lavender oil blending

PurposeThis study aims at improving combustion process to reduce emissions. Emissions such as carbon monoxide, particulate matter and unburnt hydrocarbons are a result of incomplete combustion. These emissions have useful energy but cannot be reclaimed. Hence, to enhance combustion, effect of biofuel blending on diesel combustion was investigated.Design/methodology/approachEssential oils have been found easier for blending with diesel because of simple molecular structure compared to vegetable oils. Lavender oil is an essential oil which has not yet been studied by blending with diesel. The major constituents of lavender oil are linalyl acetate (cetane number improver) and linalool (nitrogen oxides reduction). A single-cylinder, four-stroke diesel engine was run by blending diesel with lavender oil (Lavandula angustifolia oil [LAO]) in varying proportions, 5%, 10% and 15% by volume.FindingsHigher heat release rate (HRR) was observed using lavender oil blends compared to pure diesel. Compared to diesel, an increase in brake-specific fuel consumption using blends was observed. LAO15 has the lowest CO emissions at all loading conditions, 29.3% less at 100% load compared to diesel. LAO5 and LAO15 have 6.9% less HC emissions at 100% load condition compared to diesel. LAO15 has only 1.3% higher NOx emissions compared to diesel at 100% load condition. LAO5 has the lowest smoke content at all loading conditions.Research limitations/implicationsLavender oil was used directly without any processing. Tested on single-cylinder engine.Originality/valueTo the best of the author’s knowledge, currently, there is no published work on lavender oil–diesel combination. Lavender oil can provide a simple renewable solution for diesel additives with potential up to 15% blending.

Review on Mono and Hybrid Nanofluids: Preparation, Properties, Investigation, and Applications in IC Engines and Heat Transfer

Nano fluids are widely used today for various energy-related applications such as coolants, refrigerants, and fuel additives. New coolants and design modifications are being explored due to renewed interest in improving the working fluid properties of heat exchangers. Several studies have investigated nanofluids to enhance radiator and heat exchanger performance. A new class of coolants includes single, binary, and tertiary nanoparticle-based hybrid nano-coolants using ethylene glycol/deionized water combinations as base fluids infused with different nanoparticles. This review article focuses on the hydrothermal behavior of heat exchangers (radiators for engine applications) with mono/hybrid nanofluids. The first part of the review focuses on the preparation of hybrid nanofluids, highlighting the working fluid properties such as density, viscosity, specific heat, and thermal conductivity. The second part discusses innovative methodologies adopted for accomplishing higher heat transfer rates with relatively low-pressure drop and pump work. The third part discusses the applications of mono and hybrid nanofluids in engine radiators and fuel additives in diesel and biodiesel blends. The last part is devoted to a summary of the research and future directions using mono and hybrid nanofluids for various cooling applications.

Green synthesis of copper oxide nanoparticles using the Bombax ceiba plant: Biodiesel production and nano-additive to investigate diesel engine performance-emission characteristics

In this study, Bombax ceiba plant components, such as flowers and seeds, are successfully exploited as green sources in order to synthesize copper oxide nanoparticles (CuO NPs) and generate biodiesel. B. ceiba flower extract is used as a fuel-cum-reducing source for the CuO NPs synthesis through the solution combustion method. The CuO NPs were characterized through BET, FTIR, TEM, XRD, and FESEM. Particularly, the produced CuO NPs are utilized as reusable heterogeneous catalysts in the synthesis of biodiesel using a feedstock of B. ceiba oil. The maximum 95.6% biodiesel/Bombax ceiba methyl ester (BCME) is achieved at 3.5 wt% CuO NPs concentration, 60 °C temperature, an 11:1 methanol to oil (M/O) molar ratio, and a 50-min reaction time. The CuO NPs demonstrated good reusability through a negligible loss of biodiesel yield. The BCME production is consistent with a pseudo-first order reaction, with a 43.74 kJ/mol of activation energy (Ea) and 1.7 × 105 min−1 of frequency factor (A). The synthesized biodiesel is characterized through FTIR, and the fuel characteristics were estimated consistent with the ASTM 6751 standards. The metrics of green chemistry were also estimated. Further, the CuO NPs obtained through the green method are used as additives in diesel engines to study the performance and emission characteristics of the BCME diesel blend (BCME20). The CuO NPs were dispersed into the BCME-20 at varying concentrations of 50 ppm and 100 ppm. The results revealed that the brake thermal efficiency of BCME20CuO100 fuel is 2.5% higher than that of BCME20, and the reduction in BSFC is 8.3%. The engine emissions, such as HC (36.35%) and CO (43.90%) were considerably lowered when compared to BCME-20. The NOx emission of BCME20CuO100 is 5.94% lower than BCME20 and higher than diesel fuel. Further, the smoke emissions obtained for diesel, BCME20, BCME20CuO50, and BCME20CuO100 are 31%, 28%, 23%, and 18%, respectively.

Succession Patterns of Microbial Composition and Activity following the Diesel Spill in an Urban River.

Diesel spills in freshwater systems have adverse impacts on the water quality and the shore wetland. Microbial degradation is the major and ultimate natural mechanism that can clean the diesel from the environment. However, which, and how fast, diesel-degrading microorganisms could degrade spilled diesel has not been well-documented in river water. Using a combination of 14C-/3H--based radiotracer assays, analytical chemistry, MiSeq sequencing, and simulation-based microcosm incubation approaches, we demonstrated succession patterns of microbial diesel-degrading activities, and bacterial and fungal community compositions. The biodegradation activities of alkanes and polycyclic aromatic hydrocarbons (PAHs) were induced within 24 h after diesel addition, and reached their maximum after incubation for 7 days. Potential diesel-degrading bacteria Perlucidibaca, Acinetobacter, Pseudomonas, Acidovorax, and Aquabacterium dominated the community initially (day 3 and day 7), but later community structure (day 21) was dominated by bacteria Ralstonia and Planctomyces. The key early fungi responders were Aspergillus, Mortierella, and Phaeoacremonium by day 7, whereas Bullera and Basidiobolus dominated the fungal community at day 21. These results directly characterize the rapid response of microbial community to diesel spills, and suggest that the progression of diesel microbial degradation is performed by the cooperative system of the versatile obligate diesel-degrading and some general heterotrophic microorganisms in river diesel spills.

Fatty acid, fatty alcohol and acrylate derivatives as friction depressive additives for ultra-low sulphur diesel

Herein we report the synthesis of some fatty acid, fatty alcohol and acrylate derivatives as friction depressive additives for ultra-low sulphur diesel (ULSD). The high frequency reciprocating rig (HFRR) was employed to measure the wear scar diameter (WSD) of the samples. The lubricating property of the newly synthesized samples [2a, (4a-c) and (5a-c)] was studied by dosing them to ULSD at 200 ppm (wt/vol) concentrations. Amongst them, ester derived from OLA/Polyol (4c) showed the best lubrication enhancing property (WSD 328 µm) at 200 ppm(wt/vol) dosage level. Interestingly, it maintains lubricity characteristics even at a lower blending concentration of 100 ppm with a WSD value (446 µm) lower than the than the accepted value (460 µm). Notably, additives containing polar functional groups and long non-polar carbon backbone exhibited significant lubricity properties with low WSD values. Moreover, it possesses long term antiwear stability when blended with the diesel fuel and do not alter or negatively influence the physical and chemical parameters of the diesel. The FESEM and EDS analysis revealed the formation of thin defensive layer of the additive between the moving metal surfaces supporting the friction reducing properties of the additives.

Thermolysis of petroleum oil and solubility of deposits

The article discusses the process of formation of deposits in the pipelines of the engine oil system and the factors affecting the conditions for their formation. The technological process of oxidation and the criteria for indicator parameters characterizing the thermolysis of used oil are shown. An extractive method is proposed that ensures the removal of deposits from the pipeline using special flushing process fluids based on regenerated petroleum oil. To search for cheap and efficient hydrocarbon raw materials, regenerated petroleum oils were chosen from among the renewable resources of oil refining. The proposed process fluid was prepared on the basis of low-viscosity spent and then purified petroleum oil. The viscosity of the petroleum oil was adjusted with the addition of petroleum kerosene or diesel. Diluted surfactant solutions were used as additives. and detergent additive (alkali metal salts). It was revealed that in the oil system of an automobile engine at high temperatures (200-350 0C) oil thermolysis occurs, and the resulting deposits contain asphaltenes, carbons and carboids. The efficiency of dissolution of deposits in the mixture under study at low temperatures and the concentration of surfactants were revealed. The dependence of the interfacial tension on the concentration of various surfactants is shown. The limiting amounts of the content of the constituent components are found and the ratio of oily extract, from deposits of oxidized oil, is selected. As a result of the tests, it was found that the washing liquid reduces the interfacial tension between the surface of the pipes and deposits and leads to an increase in the movement of the liquid. It has been established that the process of washing off deposits depends on the composition of the deposits, as well as on the composition of the oily extract. The optimal mode and prescription composition of the flushing liquid has been selected. The efficiency of washing off the studied liquid with other means is shown, while it should be noted that this liquid has a simple component composition and is much cheaper than other means.

Thermodynamics of the heterogeneous synthesis of polyoxymethylene dimethyl ethers from paraformaldehyde and dimethoxymethane in presence of methanol and water

Polyoxymethylene dimethyl ethers (PODEn) are promising diesel additives that can reduce the exhaust emission remarkably. Although the thermodynamic model has been proposed for the homogenous synthesis of PODEn, the thermodynamics of heterogeneous synthesis of PODEn from paraformaldehyde and dimethoxymethane is still a challenge because of the complicated characteristics of paraformaldehyde. In this work, a thermodynamic model containing solid paraformaldehyde and liquid dimethoxymethane, methanol and water was established. Experimental validation showed that this model was applicable in a wide range of reaction temperature and feeding composition. This thermodynamic model was then used to study the influence of the reaction temperature, feeding ratio, and addition of water/methanol on the equilibrium conversion. The different starting compositions from heterogeneous and homogenous reactants for the synthesis of PODEn were compared based on thermodynamic analysis, showing that using paraformaldehyde and dimethoxymethane as feedstock gave the highest CH2O conversion and PODE3-5 yield.

Use of vegetable oils as environmental additives in diesel fuel

Use of vegetable oils as environmental additives in diesel fuel

Short-term arsenic mobilization, labilization, and microbiological aspects after gasoline and diesel addition in tropical soils.

The effect of the presence of gasoline and diesel on the speciation and mobility of inorganic arsenic species in tropical topsoils was investigated. Topsoil samples (n = 25) were contaminated with gasoline and diesel (500mgkg-1) in laboratory and were incubated under unsaturated conditions and regular aeration for 21days. Speciation analysis and chemical fractionation were performed in the pore water from control, gasoline, and diesel-contaminated soil samples. Arsenic concentrations were compared to microbiological parameters (microbial metabolic quotient and soil basal breathing) and the presence of ArsM-harboring bacteria. The spike of gasoline and diesel to the topsoils increased pore water As3+ (H3AsO3) concentration. Arsenic mobilization was lower compared to previously reported data for other sources of organic matter (biochar, litter, and a mixture of sphagnum peat moss and composted poultry manure). However, gasoline or diesel addition mobilized As fractions that were adsorbed to the solid phase, in approximately 60% of the soils. Methylation presented an important role in the As3+ regulation in control soils, which was no longer observed after gasoline or diesel addition. The quantification of the labile fractions sampled by the diffusive gradients in thin films technique showed that the increased As concentration in the gasoline or diesel-contaminated soils mostly included inert species. Dissolved organic carbon content seems to be an important control mechanism of the labile As concentration. The increase in As mobility seems to pose a more concerning scenario due to As leaching than to plant uptake.

Study on improving gas storage capacity of fixed bed filled with wet activated carbon

Gas hydrate technology is a new gas storage method developed in recent years and has great application potential. Due to the slow formation kinetics of hydrate and the low actual gas storage density, it is a promising method to prepare the fixed bed filled with wet porous materials to inducing adsorption-hydration coupling effect, so as to improve the gas storage efficiency. In this study, various additives including THF, TBAB and diesel oil were added to the water-bearing activated carbon fixed bed to improve its gas storage capacity. Our experimental results show that the addition of THF or TBAB can significantly promote the gas storage performance of the bed. At the optimum concentration of THF (7.5 wt%), the gas storage density of bed (Sb) and gas storage capacity of hydrate (Sw) were 128.66 V/Vb and 194.26 V/Vw, which are 2.89 times and 3.07 times higher than those of wet activated carbon fixed bed without additives, respectively. When 5 wt% TBAB was added, the Sb and Sw were increased by 1.86 times and 1.87 times, respectively. Moreover, using diesel to establish gas channels in the fixed bed to improve the gas mass transfer between the bulk gas phase and the fixed bed can also significantly improve the gas storage performance of the bed. When the oil-carbon ratio (Ro) is 0.5, the Sb and Sw are 97.97 V/Vb and 172.77 V/Vw, respectively. However, further increasing the amount of diesel oil will not significantly improve the gas storage density of the bed due to the volume increase of the bed caused by the addition of diesel. When both diesel oil and THF are added to the water-containing fixed bed, the effect will be not significantly better than that of the bed with diesel oil or THF alone because the two accelerators compete with each other. Finally, the gas release and decomposition speed of the water-bearing fixed bed with / without 7.5 wt%THF are investigated. The results show that the final gas recovery of the bed with 7.5 wt% THF could reach 95.01 %, indicating a good application prospect.