Ultra-low Sulfur Research Articles

Physicochemical Properties Enhancement of Biodiesel Synthesis from Various Feedstocks of Waste/Residential Vegetable Oils and Palm Oil

The main aim of the present study was to improve the oxidation stability and cold flow properties of biodiesel produced from waste frying/cooking oil and palm oil. In this work, waste frying/cooking methyl ester (WFME) and palm methyl ester (PME) were prepared using an alkali-catalyzed transesterification process, and the physicochemical properties of the pure biodiesel as well as of binary blends among them were investigated. The results indicated that palm biodiesel and WFME18, produced from a mixture of frying, cooking, sunflower, and corn oils, can be used as antioxidant additives, enhancing biodiesel stability. Additionally, it was found that WFME1 and WFME12 derived from waste residential canola oil can be used as cold flow improvers for enhancing the cold flow properties of palm biodiesel. Moreover, ultra-low sulfur diesel fuel winter (ULSDFW), ultra-low sulfur diesel fuel summer (ULSDFS), kerosene (KF), and benzene (BF) were utilized to enhance the cold flow properties of the samples and meet the requirements of diesel fuel standards. The investigation of the experimental results indicated that blending WFME-PM with a low proportion of petroleum-based fuel (KF and BF) could significantly improve the cold flow properties (CP and PP) as well as oxidation stability of WFME.

Characteristics of particle emissions from light duty diesel vehicle fueled with ultralow sulphur diesel and biodiesel blend

This study investigates the particle emissions from a diesel vehicle fueled with ultralow sulphur diesel (B0, ULSD) and 5 % biodiesel blend (B5) by a chassis dynamometer test under three driving conditions. Elemental carbon (EC), organic carbon (OC), 30 species of polycyclic aromatic hydrocarbon (PAH) and 10 species of oxygenated PAH (oxy-PAH) were analyzed to quantify the chemical compositions of the collected particulate matter (PM). The emission factors (EFs) of OC were increased with B5 by a range between 39.5 % and 113.7 %, compared with B0. Both fuel blends recorded a trace amount of EC (0.25 mg/kg or less). It was found that the B5 EFs of total PAHs were decreased by a range between 15.2 % and 50.2 % relative to B0. 2- to 3-ring species, the dominant PAHs and oxy-PAHs, were decreased substantially when using B5. However, the results showed that biodiesel blend promoted the emission of 4- and 5-ring oxy-PAHs and 5- to 7-ring PAHs. The application of B5 shifted the composition towards a higher proportion of PAHs with higher molecular weight and more oxy-PAHs. Due to the increased emissions in PAHs with higher toxic equivalent factors (TEFs), the application of B5 resulted in an increase in toxicity expressed in BAPeq range from 11.3 % to 117.0 %.

Comparison of waste plastic fuel, waste cooking oil biodiesel, and ultra-low sulfur diesel using a Well-to-Exhaust framework

Comparison of waste plastic fuel, waste cooking oil biodiesel, and ultra-low sulfur diesel using a Well-to-Exhaust framework

RESEARCH OF THE EFFICIENCY OF MARINE DIESEL FUEL COOLING SYSTEM ON THE BASIS OF NEW REFRIGERANTS

The requirements of the International Maritime Organization, government environmental agencies and other non-governmental groups are aimed at reducing emissions of harmful substances into the environment during the operation of diesel engines. Among these substances, the most dangerous are sulfur oxide (SOx), nitrogen oxide (NOx) and particulate matter (PM). In accordance with the specified requirements, there is an active transition to fuels with ultra-low sulfur content. The use of these fuels in marine diesel engines is associated with a number of difficulties, because these engines are usually designed for operation on fuels with high viscosity and lubricity. The viscosity values for ultra-low sulfur fuels are close to the permitted minimums for diesel engines at normal engine room temperature. The greatest difficulties occur when the viscosity values fall below the specific range when the fuel temperature before the engine increases. For reliable operation of the engine, the fuel temperature must be constantly maintained at a range in which the fuel viscosity will have the required values. For this purpose the engine design provides presence of fuel cooling system with a water cooler and a chiller for heat removal from water. In this paper the efficiency of chiller refrigeration plant was investigated using new perspective refrigerant mixtures R125/R290 and R134a/R290 as working fluids in comparison with basic R134a and R22. The values of composition for both mixtures are chosen such that they are closest to the azeotrope. It is possible for azeotrope mixtures to minimize the temperature difference between heat exchanging medias in condenser and evaporator of refrigeration plant. During the investigation it was revealed that the values of refrigeration coefficient of refrigerating plant when using mixtures as working fluids were somewhat lower when operating on R134a and R22. But the values of volumetric refrigeration capacity with mixtures as working fluids are significantly higher.

Influence of 1-butanol and 1-pentanol addition to diesel fuel on exhaust and noise emissions under stationary and transient conditions

There is a growing interest in using long-chain alcohols, i.e. butanol and pentanol, in the transport sector, as a consequence of their potential production from residual biomass via fermentative processes. There is evidence that incorporation of alcohols to diesel fuel enables to overcome the well-known smoke-NOx trade-off under steady state compression ignition engine operation. Nevertheless, the impact of long-chain alcohols under engine transient conditions is not understood and their behavior under Worldwide Harmonized Light Vehicles Test Procedure (WLTP) cycle has not been reported. This investigation addresses the above-mentioned research gaps by characterization of noise and exhaust emissions (CO, total hydrocarbon content or THC, NOx and particulate matter or PM mass, PM number and PM distribution) of a diesel engine running on ultra-low sulfur diesel (ULSD) fuel and its mixtures with 1-pentanol and 1-butanol under stationary and transient conditions (WLTP).Transient PM number, mass and size distribution have been monitored using Dekati electrical pressure low impactor ELPI + coupled by Dekati Fine Particle Sampler FPS-4000, whereas transient gaseous emissions have been measured with Horiba Mexa 7100D. Increasing the long-chain alcohol content in fuel blends, significantly reduces PM number and mass for both stationary and WLTP tests, being mainly attributed to oxygen content of 1-butanol and 1-pentanol. Addition of long-chain alcohols causes a decrease of emitted NOx in stationary operation, but the opposite trend was found under WLTP. Noise levels seem to slightly increase with the use of higher alcohol/ULSD fuel mixtures. Overall, it may be concluded that utilization of higher alcohol/ULSD fuel blends appears as a favorable substitute to straight ULSD fuel.

An Experimental Study on the Performance Characteristics of a Diesel Engine Fueled with ULSD-Biodiesel Blends

As a rule, the highest permissible sulfur content in the marine fuel must drop below 0.5% from 1 January 2020 for global fleets. As such, ships operating in emission control areas must use low sulfur or non-sulfur fuel to limit sulfur emissions as a source of acid rain. However, that fact has revealed two challenges for the operating fleet: the very high cost of ultra-low sulfur diesel (ULSD) and the installation of the fuel conversion system and the ULSD cooling system. Therefore, a solution that blends ULSD and biodiesel (BO) into a homogeneous fuel with properties equivalent to that of mineral fuels is considered to be significantly effective. In the current work, an advanced ultrasonic energy blending technology has been applied to assist in the production of homogeneous ULSD-BO blends (ULSD, B10, B20, B30, and B50 with blends of coconut oil methyl ester with ULSD of 10%, 20%, 30% and 50% by volume) which is supplied to a small marine diesel engine on a dynamo test bench to evaluate the power and torque characteristics, also to consider the effect of BO fuel on specific fuel consumption exhaust gas temperature and brake thermal efficiency. The use of the ultrasonic mixing system has yielded impressive results for the homogeneous blend of ULSD and BO, which has contributed to improved combustion quality and thermal efficiency. The results have shown that the power, torque, and the exhaust gas temperature, decrease by approximately 9%, 2%, and 4% respectively with regarding the increase of the blended biodiesel rate while the specific fuel consumption and brake thermal efficiency tends to increase of around 6% and 11% with those blending ratios.

Modeling, simulation, and optimization for producing ultra-low sulfur and high-octane number gasoline by separation and conversion of fluid catalytic cracking naphtha

Contradiction between the desulfurization and loss of octane number (ON) for fluid catalytic cracking (FCC) naphtha is the long-term problem of clean gasoline production. Moreover, ON loss is substantially aggravated during deep hydrodesulfurization because of the global limited supply of sulfur for gasoline. This paper introduced a novel process for ultra-clean gasoline production that solves the above problem by using a unique separation approach. The components were separated by the coupling of distillation and solvent extraction, which the separation efficiency depends on the relationship between solvent and feedstock components. However, the compositions of FCC naphtha are complicated and always changing due to different processing technologies. Therefore, changes in the material composition must be considered during production. In this study, ternary liquid–liquid equilibrium (LLE) was explored to investigate the interaction of olefin, sulfide, and sulfolane solvent. A universal quasi-chemical functional group activity coefficient (UNIFAC) group contribution model was selected to predict the product composition when the FCC naphtha was treated by this process. The lack and necessity of group interaction parameters for the prediction were obtained through the regressive calculation of LLE results. A simulation method was established by Aspen Plus, and the reliability was well illustrated. Finally, the high olefin content of FCC naphtha critical components was analyzed by this simulation method. The sulfur and olefin levels of the product were 9.0 mg/kg and 18.6 wt%, respectively. The operation conditions simulated using the proposed technique met the requirements for the latest commercial gasoline worldwide.

Immobilized Multifunctional Ionic Liquids for Highly Efficient Oxidation of Sulfur-Containing Compounds in Model Fuels

Oxidative desulfurization is a promising method to produce clean fuels with an ultralow sulfur content at mild conditions. Herein, for the first time, we present multifunctional ionic liquid catalysts immobilized on mesoporous SBA-15 for highly efficient oxidation of dibenzothiophene. A combination of two active catalytic sites (phosphomolybdic acid fragment and carboxylic group) allows us to achieve complete oxidation of the most intractable dibenzothiophene to the corresponding sulfone in 5 min at 80 °C and H2O2/S = 6:1 molar ratio. The support and catalyst structures were investigated by low-temperature nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, X-ray fluorescence analysis, CHN analysis, and transmission electron microscopy techniques. Nicotinic acid fragments, bonded with the support and phosphomolybdic acid anion via covalent and ionic bonds, respectively, prevent active site leaching, thus retaining the catalyst activity for at least 10 reaction runs with preliminary regeneration. These catalysts are considered as promising systems for clean fuel production.

Ultrasound-Assisted Hydrothermal Synthesis of V2O5/Zr-SBA-15 Catalysts for Production of Ultralow Sulfur Fuel

This work reports the results of the ultrasound-assisted hydrothermal synthesis of two sets of V2O5 dispersed on SBA-15 and Zr doped SBA-15 catalysts used for the oxidation of dibenzothiophene (DBT) in a model diesel via the combination of oxidation, catalysis, and extraction technical route. These catalysts contained Lewis acidity as major and Brønsted acidity as minor. The amount of acidity varied with the content of vanadia and zirconium doping. It was found that DBT conversion is very sensitive to the Lewis acidity. DBT conversion increased by increasing the vanadium content and correlated well with the amount of surface Lewis acidity. Under the optimal experimental condition (Reaction temperature: 60 °C, reaction time 40 min, catalyst concentration: 1 g/L oil; H2O2/DBT mole ratio = 10), the 30% V2O5/SBA-15 and 30% V2O5/Zr-SBA-15 catalysts could convert more than 99% of DBT. Two reaction pathways of DBT oxidation involving vanadia surface structure, Lewis acidity, and peroxometallic complexes were proposed. When the vanadia loading V2O5 ≤ 10 wt%, the oxidative desulfurization (ODS) went through the Pathway I; in the catalysts with moderate vanadia content (V2O5 = 20–30 wt%), ODS proceeded via the Pathways II or/and the Pathway I.

Single-atom Pt promotion of industrial Co-Mo-S catalysts for ultra-deep hydrodesulfurization

We introduce a tertiary transition metal sulfide nanostructure, Pt-Co-Mo-S, for catalytic hydrodesulfurization (HDS) of sulfur-containing molecules in crude oil distillates with the aim to produce ultra-low sulfur transport fuels. The addition of ppm-levels of Pt to a standard industrial Co-Mo-S catalyst boosts the HDS activity by up to 46%. The promotional effect is examined by combining atomic-resolution Scanning Transmission Electron Microscopy (STEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Absorption Near Edge Spectroscopy (XANES) and Density Functional Theory (DFT). It is shown that the Pt-Co-Mo-S catalyst contains predominantly single-layer MoS2 nanocrystals with Co atoms fully covering the S-edge terminations and Pt atoms uniquely attached to corner and edge sites in a platinum(IV) sulfide-like structural motif. Platinum is suggested to reduce the sulfur binding energy and increase the abundance of coordinately undersaturated sites (CUS) and not necessarily changing the reactivity towards 4,6-DMDBT molecules, although more elaborate studies are needed to address this in detail.

Prediction of ultra low sulphur diesel catalyst performance using limited pilot plant data

Due to the presence of refractory sulphur (S) compounds in the gasoil, the achievement of Ultra-low-Sulphur Diesel (ULSD) using the conventional bimetallic catalyst in the Hydrodesulphurization (HDS) process in order to bring sulphur down to less than 10 ppmwt is considered as a tough task/challenge and gain major attention due to the EPA regulations on the transportation fuel industry.In this work, a catalytic testing of four commercial alumina-supported cobalt–molybdenum (CoMo) catalysts were conducted using fixed bed pilot plant reactor using a complex real mixture of straight run gasoil fraction (C12-C20) in order to determine the operating conditions at industrial unit particularly by focusing on the refractory (S) compounds and determining their reaction kinetics parameters. A limited pilot plant real data and a simplified kinetic model were employed to estimate the kinetic parameters for the four tested CA, CB, CC and CD catalysts. A parameter estimation technique with explicit models was also used to determine their highest posterior density intervals. The technique is based on minimization of the sum of the square errors (SSE) between the experimental and predicted data of the residual sulphur concentrations in the product distributions. The results revealed that each catalyst showed, expectedly, different results translated into how longer a commercial run length can be extended.

Low-pressure hydrothermal processing of mixed polyolefin wastes into clean fuels

The amount of polyolefin waste, which is 63% of the total plastic waste, has grown exponentially over the past six decades. Its degradation products pose a serious threat to ecosystems and human health. Polyolefins can be converted to clean oils or fuels by using the supercritical water liquefaction (SWL) method at high pressures (≥23 MPa), which require high capital and energy costs. A new low-pressure (~2 MPa) hydrothermal processing (LP-HTP) method is developed to convert polyolefin waste with 50% or more polypropylene into oils with 87% yield at 450 °C and 45 min. The oils, which are C4 to C25 hydrocarbons, can be distilled into clean gasoline and ultra-low sulfur diesel. With this method, up to 190 million tons of fuels can be produced annually from polyolefin waste, resulting in savings of 92% of the energy and 71% of the GHG emissions compared to conventional methods for producing fuels.

Natural clay nanotube supported Mo and W catalysts for exhaustive oxidative desulfurization of model fuels

Abstract Oxidative desulfurization is a promising way to produce, under mild conditions, clean ecological fuels with ultra-low sulfur content. Herein, we present for the first time heterogeneous catalysts based on natural aluminosilicate nanotubes (halloysite) loaded with transition metal oxides for oxidative sulfur removal using hydrogen peroxide as environmentally safe oxidant. The halloysite nanotubes (HNTs) provide acid sites for C–S bond scission, while the Mo and W oxides act as hydrogen peroxide activators. The structure and acidity of both the clay support and catalysts were investigated by low-temperature nitrogen adsorption/desorption, Fourier-transform infrared spectroscopy, X-ray fluorescence analysis, and transmission electron microscopy techniques. These clay-based catalysts revealed the high activity in the oxidation of various classes of sulfur-containing compounds (sulfides, heteroatomic sulfur compounds) under mild reaction conditions. The conversion of various substrates decreases in the following trend: MeSPh > Bn2S > DBT > 4-MeDBT > BT, which deals with substrate electron density and steric hindrance. The influence of the temperature, oxidant to sulfur molar ratio, and reaction time on catalytic behavior was evaluated for Mo- and W-containing systems with various metal content. The complete oxidation of the most intractable dibenzothiophene to the corresponding sulfone was achieved at 80 °C and H2O2:S = 6:1 (molar) for 2 h both for Mo- and W-containing systems. These transition metal oxides HNTs supported catalysts are stable for 10 cycles of dibenzothiophene oxidation, which makes them promising systems for clean fuel production.

Formulation and tribological behavior of ultra-low sulfur diesel fuels microemulsified with glycerin

The lubricity of diesel is a fundamental parameter, as it has a direct impact on the engine operation, working life and wear of the parts. Ultra-low sulfur diesel fuels (ULSD) have low lubricity due to the removal of polar compounds resulted from the desulfurization process. This study evaluated the impact of glycerin addition on the lubrication properties of ULSD microemulsion fuel. Lubricity tests were developed in High Frequency Reciprocating Rig (HFRR). The results showed that, when compared to the ULSD reference fuel with 10 ppm sulfur, the addition of glycerin at the highest concentration was capable to double the percentage of lubricant film formation, reduce by 48% the wear scar formed in the steel ball and promote the reduction in the values of roughness parameters by approximately 50%.

Construction of bifunctional 3-D ordered mesoporous catalyst for oxidative desulfurization

The development of catalysts with the functions of catalyzing the oxidation of organosulfur and separating the products from reaction mixturesis facilitates to achieve high-efficiency oxidative desulfurization (ODS) of fuel. Herein, the MoO3 nanoparticles (mean diameter = 1.33 nm) confined in Ti-doped KIT-6 could be synthesized by triblock copolymer (EO20PO70EO20)-assisted in-situ synthesis method combined with stepwise pyrolysis. The prepared catalyst (Mo/KIT-6-Ti) exhibited excellent ODS performance. When cumene hydroperoxide (CHP) was used as the oxidant, Mo/KIT-6-Ti not only could completely remove dibenzothiophene (DBT) in the model gasoline at room temperature in 40 min but also had the excellent ability to adsorb and separate the sulfone product from the model gasoline. After five reaction-regeneration cycles, the DBT conversion over Mo/KIT-6-Ti still reached above 99% in 60 min. Furthermore, kinetic studies revealed that the oxidation reaction of DBT on Mo/KIT-6-Ti had extremely low activation energy (34.9 kJ/mol). Data from radical scavenger experiments suggested that hydroxyl radicals play a dominant role in the ODS. This catalyst has the potential to negate the need for a solvent extraction step in fuel desulfurization and produce ultralow sulfur fuel.

Experimental investigation of the effect of temperature on ignition of modified kerosene

Kerosene based hydrocarbon fuels are preferred candidates for the source of energy due to its stable properties. Based on the requirement of the combustor and the growing concern over pollutant, kerosene based fuels are modified. The fuel under investigation is a modified form of kerosene with ultra-low sulphur content. The effect of temperature on modified kerosene is studied for viscosity, surface tension, specific heat, density and ignition delay. The time delay for ignition of gas-phase mixtures of modified kerosene/oxygen have been measured using a shock tube facility. The experiments are conducted in the temperature range of 1200–1877 K, pressure range of 4–12 atm and equivalence ratio of Ø = 1.5, 1 and 0.5. The ignition delay time measurements were carried out using piezoelectric pressure transducers, which records the pressure rise due to ignition and simultaneously recording the light emission during the process of ignition using a photodiode. The ignition delay is represented as τign = 0.168841 × P−1.49 × Ø0.72 × e(14310/T)

Modeling of catalytic adsorptive desulfurization in a cyclic process

Catalytic adsorptive desulfurization (CADS) recently received attention due to its integrated nature in reaching ultra-low sulfur content fuel. In this study, a mathematical model is used to simulate catalytic adsorptive behavior for a model fuel of toluene with 300 ppm di-benzothiophene over TiO2/SBA-15 catalyst. The results showed that near 100% sulfur removal can be obtained for the model fuel and negligible heat is released in the reactor. Cyclic temperature swing adsorption is studied and after one cycle, the process reached to steady state condition. The effect of addition of methanol in regeneration of adsorbent is also investigated and the results showed that injection of methanol would add some benefits into the process of desulfurization in terms of late breakthrough happening and reduction in di-benzothiophene concentration in the bed. A comparison between catalytic adsorptive (CADS), oxidative-adsorption (OADS) and adsorption desulfurization (ADS) methods is also conducted and the results showed that the first process provides a higher adsorption capacity.

Lubricity assessment of ultra-low sulfur diesel fuel (ULSD), biodiesel, and their blends, in conjunction with pure hydrocarbons and biodiesel based compounds

This research aimed to investigate the lubricity and wear properties of ultra-low sulfur diesel fuel (ULSD) blended with biodiesel and doped with biodiesel-based organic compounds. In this work, neat n-dodecane served as a surrogate for ultra-low sulfur diesel fuel (ULSD), Fischer Tropsch, and renewable diesel fuels. Additionally, some pure hydrocarbons were also investigated for unsaturation and carbon chain length. Tribological characterization was conducted on quenched and tempered AISI 4140 steel, substituting diesel fuel pump material, and using the ball-on-disc technique. The wear rates of biodiesel samples were about 2–4 times less than the vegetable oils. Esterification improves the lubricity of vegetable oils. The wear rate of biodiesel is about 5–7 times greater than that of fossil base commercial Eurodiesel fuel. Using biodiesel as an additive had a significant effect on the lubricity of pure n-dodecane, adding 2 wt% biodiesel resulted in 5–7 times wear rate reduction that equivalent to the lubricity level of commercial Eurodiesel fuel. Wear rates of pure hydrocarbons showed that wear is reduced with increasing chain length and unsaturation.

Nitrogen compounds removal from oil-derived middle distillates by MIL-101(Cr) and its impact on ULSD production by hydrotreating

Oil-derived middle distillates (straight-run gas oil and mixture with light cycle oil and coker gas oil) for Ultra-Low Sulfur Diesel (ULSD) production by HyDroTreating (HDT) were pretreated by selective Nitrogen Organic Compounds (NOC) adsorption. Highly crystalline Metal-Organic Framework (MOF) MIL-101(Cr) prepared with propylene oxide (proton scavenger) as textural improver was used to that end. MOF was characterized by N2 physisorption, X-ray diffraction, thermal analysis, infrared, Raman and UV-vis spectroscopies, and electron microscopy (SEM and HR-TEM). NOC removal was carried out at room temperature and atmospheric pressure, the adsorbent being easily regenerable under mild conditions. Extruded MOF efficiently removed NOC from real feedstocks to concentrations ~ 80 ppm which allowed ULSD production at much milder conditions to those used during pristine feedstocks HDT. Operating temperature could be significantly diminished (from 350 to 330 °C, at 56 kg cm−2 (5.77 MPa), LHSV = 1.5 h−1, H2/oil = 2500 ft3 bbl−1 (445 m3 m−3)) which could notably prolong cycle life of NiMo/Al2O3 formulation used.

Dilatational rheology of water-in-diesel fuel interfaces: effect of surfactant concentration and bulk-to-interface exchange.

Micrometer-sized water droplets dispersed in diesel fuel are stabilized by the fuel's surface-active additives, such as mono-olein and poly(isobutylene)succinimide (PIBSI), making the droplets challenging for coalescing filters to separate. Dynamic material properties found from interfacial rheology are known to influence the behavior of microscale droplets in coalescing filters. In this work, we study the interfacial dilatational properties of water-in-fuel interfaces laden with mono-olein and PIBSI, with a fuel phase of clay-treated ultra-low sulphur diesel (CT ULSD). First, the dynamic interfacial tension (IFT) is measured using pendant drop tensiometry, and a curvature-dependent form of the Ward and Tordai diffusion equation is applied for extracting the diffusivity of the surfactants. Additionally, Langmuir kinetics are applied to the dynamic IFT results to obtain the maximum surface concentration (Γ∞) and ratio of adsorption to desorption rate constants (κ). We then use a capillary pressure microtensiometer to measure the interfacial dilatational modulus, and further extract the characteristic frequency of surfactant exchange (ω0) by fitting a model assuming diffusive exchange between the interface and bulk. In this measurement, 50-100 μm diameter water droplets are pinned at the tip of a glass capillary in contact with the surfactant-containing fuel phase, and small amplitude capillary pressure oscillations over a range of frequencies from 0.45-20 rad s-1 are applied to the interface, inducing changes in interfacial tension and area to yield the dilatational modulus, E*(ω). Over the range of concentrations studied, the dilatational modulus of CT ULSD with either mono-olein or PIBSI increases with a decrease in bulk concentration and plateaus at the lowest concentrations of mono-olein. Characteristic frequency (ω0) values extracted from the fit are compared with those calculated using equilibrium surfactant parameters (κ and Γ∞) derived from pendant drop tensiometry, and good agreement is found between these values. Importantly, the results imply that diffusive exchange models based on the equilibrium relationships between surfactant concentration and interfacial tension can be used to infer the dynamic dilatational behavior of complex surfactant systems, such as the water-in-diesel fuel interfaces in this study.