Mixture Of Hexadecane Research Articles

Onion-like carbon as nano-additive for tribological nanogenerators with enhanced output performance and stability

Triboelectric nanogenerators (TENGs) with sliding-mode have developed rapidly in the field of energy harvesting and sensing. However, its surface wear and low electric output performance usually limit its applicability. Herein, a mixture of hexadecane with onion-like carbon (OLC) lubricant is added to the interface between polytetrafluoroethylene (PTFE) film and steel to enhance the triboelectrical and tribological performance. During dry friction, the friction pair is severely worn and the current output decreases gradually with the transfer of a large amount of PTFE debris in a short period. The introduction of hexadecane partly resolves the problems such as friction and wear with the reduction in the transfer of PTFE material. However, the current output decreases gradually during the friction process because there is still some slight material transfer in the interface. The electrical output of TENG is further enhanced with the addition of OLC, and its tribological properties are comparable or better than oil-based TENG. The short-circuit currents (Isc) of the oil-based TENG and the oil-OLC-based TENG are 1.5 times and 5 times that of the TENG in the dry friction state, respectively. Also, the coefficient of friction (COF) of oil-OLC-based TENG is reduced by about 75.3% compared with dry friction state. The oil-OLC-based lubricant reduces the transfer film formation, increases the effective contact area, and squeezes the air at the interface. Also, part of the OLC rolls between the two friction layers, forming a "micro-bearing", further reducing the generation of transfer film. This study provides a novel way to improve the output efficiency and prolong the service life of TENG.

Optical Properties of a Tapered Optical Fiber Coated with Alkanes Doped with Fe3O4 Nanoparticles

The presented research shows the possibilities of creating in-line magnetic sensors based on the detection of changes of light propagation parameters, especially polarization, obtained by mixing Fe3O4 nanoparticles with hexadecane (higher alkane) surrounding a biconical optical fiber taper. The fiber optic taper allows to directly influence light parameters inside the taper without the necessity to lead the beam out of the structure. The mixture of hexadecane and Fe3O4 nanoparticles forms a special cladding surrounding a fiber taper which can be controlled by external factors such as the magnetic field. Described studies show changes of transmission (power, loss) and polarization properties like azimuth, and ellipticity, depending on the location of the mixture on sections of tapered optical fiber. The taper was made of a standard single-mode telecommunication fiber, stretched out to a length of 20.0 ± 0.5 mm and the diameter of the tapers is around 15.0 ± 0.3 μm, with the loss lower than 0.5 dB @ 1550 nm. Such a taper causes the beam to leak out of the waist structure and allows the addition of the external beam-controlling cladding material. The presented research can be used to build polarization switches or optical sensor. The results show that it can be a new way to control the propagation parameters of a light beam using tapered optical fiber and magnetic mixture.

Biodegradation kinetics of binary mixture of hexadecane and phenanthrene by the bacterial microconsortium

Crude oil bioremediation requires a correct selection of potential biodegraders to address the hazard. The present study investigates biodegradation kinetics of single aliphatic (Hexadecane, HEX), aromatic (Phenanthrene, PHE), and binary mixture (HEX + PHE) as co-contaminants by axenic cultures of A. fabrum SLAJ 731, B. subtilis RSL2 and P. aeruginosa P7815 and their consortium. A proposed integrated kinetic model combining first-order exponential decay and the Monod equation is well-fitted to degradation data. Maximum degradations of both the substrates were observed for microcosm, indicating synergistic effects of selected strains. The degradation rate indicated parallel utilization of HEX while serial utilization of PHE by selected strains. Maximum HEX and PHE degradations of 92.4 and 88.7 % were achieved by microconsortium, which increased to 97.2 and 91.9 % for the binary mixture. The biodegradation efficiencies of HEX and PHE were linearly correlated with Alkane hydroxylase and Catechol-2,3-dioxygenase activities, respectively.

Modeling and Numerical Solution of the Fate of Multicomponent Substrate in Porous Media

A mathematical model was proposed to appropriately describe the fate of multicomponent substrates in porous media especially soil. The model utilised appropriate biodegradation kinetic expressions that better describe the consumption or degradation rate of the substrate. The Equation, with the second and third type boundary conditions in non-dimensionalised form was solved using the Finite Volume method and simulated in the Matlab environment. An experiment, using a 5 cm (inside diameter) x 60 cm (height) glass column packed with severally autoclaved soil spiked with 2 % substrate (a mixture of hexadecane, heneicosane, 1-methylnaphthalene, 2- methylnaphthalene and 1, 3-dimethylnapthalene) and a consortium of organisms (Providential rettgeri, Streptococcus salivarius, Trichoderma harzianum, Aspergillus flavipes, and Candida famata) was set up to validate the model. The result showed that the model describes the fate of each component within the multicomponent substrate. It also indicates that both Peclet and Thiele numbers affect the biodegradation of the substrate. It was observed that small Peclet number should be allowed for effective biodegradation of the substrate. The model was validated with data obtained for an experiment where a mixture of hydrocarbons was degraded with a mixed culture of microorganisms. The results of the experiment were well described by the model indicating that the model can be used to predict compositions of components of a mixture during biodegradation.

Density and Volumetric Properties of Binary Mixtures of CO2 + Hexadecane from (303.2 to 473.2) K and Pressures up to 50.0 MPa

Densities of CO2 + hexadecane binary mixtures were measured by the capillary high-pressure optical cell method at temperatures from 303.2 to 473.2 K and pressures up to 50.0 MPa with CO2 molar fractions x1 = 0, 0.2555, 0.3703, 0.7348, and 0.8645. The density and excess molar volume of CO2 + hexadecane mixtures are the positive correlation function of pressure and the negative correlation function of temperature. The dissolution of CO2 increases the density of mixtures at low temperatures and decreases the density of mixtures at high temperatures. The crossover temperature increases with increasing pressure. The perturbed-chain statistical associating fluid theory (PC-SAFT) parameters of pure substances were fitted, and the densities of CO2 + hexadecane mixtures can be calculated accurately with the PC-SAFT model.

A strain-controlled RheoSANS instrument for the measurement of the microstructural, electrical, and mechanical properties of soft materials.

In situ measurements are an increasingly important tool to inform the complex relationship between nanoscale properties and macroscopic material measurements. Knowledge of these phenomena can be used to develop new materials to meet the performance demands of next generation technologies. Conductive complex fluids have emerged as an area of research where the electrical and mechanical properties are key design parameters. To study the relationship between microstructure, conductivity, and rheology, we have developed a small angle neutron scattering (SANS) compatible Couette rheological geometry capable of making impedance spectroscopy measurements under continuous shear. We have also mounted this geometry on a commercial strain controlled rheometer with a modified forced convection oven. In this manuscript, we introduce the simultaneous measurement of impedance spectroscopy, rheological properties and SANS data. We describe the validation of this dielectric RheoSANS instrument and demonstrate its operation using two systems-an ion gel comprising Pluronic® surfactant and ionic liquid, ethyl-ammonium nitrate, and poly(3-hexylthiophene) organogel prepared in a mixture of hexadecane and dichlorobenzene. In both systems, we use this new measurement capability to study the microstructural state of these materials under two different protocols. By monitoring their dielectric rheology at the same time as the SANS measurement, we demonstrate the capacity to directly probe structure-property relationships inherent to the macroscopic material response.

SL2B aptamer and folic acid dual-targeted DNA nanostructures for synergic biological and chemotherapy to combat colorectal cancer

The influence of chemical structure on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux was examined. The variability of measured and UNIFAC modeled NAPL activity coefficients as a function of mole fraction was compared for two NAPL mixtures containing structurally-different contaminants of concern including toluene (TOL) or trichloroethene (TCE) within a hexadecane (HEXDEC) matrix. The results showed that dissolution from the NAPL mixtures transitioned from ideality for mole fractions > 0.05 to nonideality as mole fractions decreased. In particular, the TCE generally exhibited more ideal dissolution behavior except at lower mole fractions, and may indicate greater structural/polarity similarity between the two compounds. Raoult's Law and UNIFAC generally under-predicted the batch experiment results for TOL:HEXDEC mixtures especially for mole fractions ≤ 0.05. The dissolution rate coefficients were similar for both TOL and TCE over all mole fractions tested. Mass flux reduction (MFR) analysis showed that more efficient removal behavior occurred for TOL and TCE with larger mole fractions compared to the lower initial mole fraction mixtures (i.e. < 0.2). However, compared to TOL, TCE generally exhibited more efficient removal behavior over all mole fractions tested and may have been the result of structural and molecular property differences between the compounds. Activity coefficient variability as a function of mole fraction was quantified through regression analysis and incorporated into dissolution modeling analyses for the dynamic flushing experiments. TOL elution concentrations were modeled (predicted) reasonable well using ideal and equilibrium assumptions, but the TCE elution concentrations could not be predicted using the ideal model. Rather, the dissolution modeling demonstrated that TCE elution was better described by the nonideal model whereby NAPL-phase activity coefficient varied as a function of COC mole fraction. For dynamic column flushing experiments, dissolution rate kinetics can vary significantly with changes in NAPL volume and surface area. However, under conditions whereby NAPL volume and area are not significantly altered during dissolution, mixture nonideality effects may have a greater relative control on dissolution (elution) and MFR behavior compared to kinetic rate limitations.

Chemical structure influence on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux

The influence of chemical structure on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux was examined. The variability of measured and UNIFAC modeled NAPL activity coefficients as a function of mole fraction was compared for two NAPL mixtures containing structurally-different contaminants of concern including toluene (TOL) or trichloroethene (TCE) within a hexadecane (HEXDEC) matrix. The results showed that dissolution from the NAPL mixtures transitioned from ideality for mole fractions >0.05 to nonideality as mole fractions decreased. In particular, the TCE generally exhibited more ideal dissolution behavior except at lower mole fractions, and may indicate greater structural/polarity similarity between the two compounds. Raoult's Law and UNIFAC generally under-predicted the batch experiment results for TOL:HEXDEC mixtures especially for mole fractions ≤0.05. The dissolution rate coefficients were similar for both TOL and TCE over all mole fractions tested. Mass flux reduction (MFR) analysis showed that more efficient removal behavior occurred for TOL and TCE with larger mole fractions compared to the lower initial mole fraction mixtures (i.e. <0.2). However, compared to TOL, TCE generally exhibited more efficient removal behavior over all mole fractions tested and may have been the result of structural and molecular property differences between the compounds. Activity coefficient variability as a function of mole fraction was quantified through regression analysis and incorporated into dissolution modeling analyses for the dynamic flushing experiments. TOL elution concentrations were modeled (predicted) reasonable well using ideal and equilibrium assumptions, but the TCE elution concentrations could not be predicted using the ideal model. Rather, the dissolution modeling demonstrated that TCE elution was better described by the nonideal model whereby NAPL-phase activity coefficient varied as a function of COC mole fraction. For dynamic column flushing experiments, dissolution rate kinetics can vary significantly with changes in NAPL volume and surface area. However, under conditions whereby NAPL volume and area are not significantly altered during dissolution, mixture nonideality effects may have a greater relative control on dissolution (elution) and MFR behavior compared to kinetic rate limitations.

Viscosities and Densities of Binary Mixtures of Hexadecane with Dissolved Methane or Carbon Dioxide at Temperatures from (298 to 473) K and at Pressures up to 120 MPa

We report measurements of the viscosity and density of two binary mixtures comprising hexadecane with dissolved carbon dioxide or methane over the temperature range from (298.15 to 473.15) K and at pressures up to 120 MPa. The measurements were conducted at various mole fractions x of the light component as follows: x = (0, 0.0690, 0.5877, and 0.7270) for xCO2 + (1 – x)C16H34 and x = (0, 0.1013, 0.2021, 0.2976, and 0.3979) for xCH4 + (1 – x)C16H34. The viscosity and density measurements were carried out simultaneously using a bespoke vibrating-wire apparatus with a suspended sinker. With respect to the first mixture, the apparatus was operated in a relative mode and was calibrated in octane whereas, for the second mixture, the apparatus was operated in an absolute mode. To facilitate this mode of operation, the diameter of the centerless-ground tungsten wire was measured with a laser micrometer, and the mass and volume of the sinker were measured independently by hydrostatic weighing. In either mode of op...

Combined Nano- and Macrotribology Studies of Titania Lubrication Using the Oil-Ionic Liquid Mixtures

The lubrication of titania surfaces using a series of ionic liquid (IL)–hexadecane mixtures has been probed using nanoscale atomic force microscopy (AFM) and macroscale ball-on-disk tribometer measurements. The IL investigated is trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate, which is miscible with hexadecane in all proportions. At both length scales, the pure IL is a much more effective lubricant than pure hexadecane. At low loads, which are comparable to common industrial applications, the pure IL reduces the friction by 80% compared to pure hexadecane; while the IL–hexadecane mixtures lubricate the titania surface as effectively as the pure IL and wear decreases with increasing IL concentration. At high test loads the adsorbed ion boundary layer is displaced leading to surface contact and high friction, and wear is pronounced for all IL concentrations. Nonetheless, the IL performs better than a traditional zinc–dialkyl–dithophosphate (ZDDP) antiwear additive at the same concentr...

Effect of temperature on the viscoelastic properties of nano-confined liquid mixtures.

The behaviour of fluids confined in nanoscale gaps plays a central role in molecular science and nanofluidics, with applications ranging from biological function to multiscale printing, osmosis and filtration, lab-on-chip technology and friction reduction. Here atomic force microscopy is used to shear five different mixtures of hexadecane and squalane confined between the tip apex and atomically flat graphite. The shearing amplitudes are typically <2 nm, hence reflecting highly localised information at the interface. The evolution of each mixture's viscoelastic properties is studied as a function of temperature, between 20 °C and 100 °C. The results, complemented by sub-nanometre resolution images of the interface, show that spatial organisation of the liquid molecules at the surface of graphite largely dominates the measurements. Squalane presents a higher effective affinity for the surface by forming a robust self-assembled layer in all mixtures. This results in a step-like change of the viscous and elastic response of the confined liquid as the confining pressure increases. In contrast, measurements in pure hexadecane show a continuous and linear increase in the apparent viscosity with pressure at all temperatures. This is interpreted as a more fragile interfacial layer and images show that it can be completely removed at high temperatures. Depending on the mixture composition, measurements can be strongly location-dependent which suggests molecular clustering and nanoscale phase separation at the interface.

Liquid–Liquid Equilibria for Mixtures of Hexadecane and Ethanol with Imidazolium-Based Ionic Liquids

The applicability of 1-alkyl-imidazoluim-based ionic liquids (ILs) for the extraction of ethanol from hexadecane by solvent extraction was studied by determining the liquid–liquid equilibrium (LLE) data for the ternary systems: {hexadecane (1) + ethanol (2) + 1,3-dimethylimidazolium methyl sulfate, [MMIM][MeSO4] (3) or 1-ethyl-3-methylimidazolium methyl sulfate, [EMIM][MeSO4] (3), or 1-butyl-3-methylimidazolium methyl sulfate, [BMIM][MeSO4] (3)} at T = 298.15 K and p = 1 atm. The selectivities and distribution coefficients of the solute, derived from the measured tie-line data, were used to examine the ability of these ILs as solvents to extract ethanol from a hexadecane-ethanol mixture. The temperature dependency was investigated by measuring the LLE data for {hexadecane (1) + ethanol (2) + [MMIM][MeSO4] (3)} at T = 313.15 K and p = 1 atm. The Othmer–Tobias and Hand equations were used to establish the quality of the LLE data. Finally, the experimental tie-line data were correlated using the Non-Random Two Liquid model.

Phase behavior of dodecane–hexadecane mixtures in bulk and confined in SBA-15

Phase behaviors of dodecane–hexadecane (n-C12H26–C16H34, C12–C16) binary mixtures in bulk and confined in SBA-15 (pore diameters 3.8, 9.5, and 17.2 nm) are investigated using differential scanning calorimetry. According to the thermal analysis, the bulk mixtures belong to a system of partial miscibility with two solid solutions and a eutectoid in the range of mole fraction \( x_{{{\text{C}}_{ 1 6} }} \) = 0.1–0.8. Under confinement, phase behavior of C12–C16 mixtures is distinct from the bulk. Inside pores of SBA-15 (3.8 nm), the solid mixtures has only a melting boundary. In the pores larger than 9.5 nm, phase behaviors of the mixtures show some resemblance to the bulk system. The growth of the phase diagram with the pore diameter clearly shows the size effect on the phase behavior of the confined mixtures. In comparison with those of chain length difference of pure components of two carbon atoms or less, C12–C16 mixtures exhibit different phase behaviors not only in the bulk but also in the confined state.

Effect of nozzle dimensions and fuel type on flame lift-off length

Flame lift-off length of diesel fuel has significant influence on fuel–air mixture and soot formation. The results of the investigation on flame lift-off length are presented in this study. Experimental and numerical studies were conducted on a constant volume combustion chamber. To investigate the influence of injector nozzle geometry, four different types; namely divergent, straight, straight–rounded and convergent–rounded nozzles, were used in the experiments. Experiments were carried at 825K and 3.5MPa ambient conditions. To investigate the effect of fuel type, diesel fuel, n-heptane and a mixture of hexadecane–heptamethylnonane CN65 (cetane number 65) were injected by straight–rounded nozzle. The experimental results showed that the nozzle with smaller diameter and divergent shape has shorter flame lift-off length, that is thought to be related to lesser amount of injected fuel. Other nozzles have almost the same flame lift-off length. The experiments, conducted with fuels of different cetane number but similar heating values, showed that fuel type has insignificant effect on flame lift-off length. This result can be attributed to similar adiabatic flame temperature obtained after flame stabilization. In order to explain the driving parameters of flame lift-off length, KIVA3V CFD code was used in the numerical simulations which were carried under different ambient temperature and oxygen concentrations. It was concluded that the location of flame stabilization is effected by the flame temperature and the reverse motion of high temperature gas of combustion zone.

Encapsulated Triplet–Triplet Annihilation-Based Upconversion in the Aqueous Phase for Sub-Band-Gap Semiconductor Photocatalysis

We herein report the first instance of aqueous-phase photosensitization of semiconductor photocatalysts (WO(3) loaded with Pt) through triplet-triplet annihilation (TTA)-based upconversion of sub-band-gap photons. The TTA-based upconversion (UC) was achieved in the aqueous phase by encapsulating the solvent phase containing a benchmark platinum(II) octaethylporphyrin/9,10-diphenylanthracene sensitizer/acceptor pair in a rigid polymer shell in the form of aqueous dispersible microcapsules. A mixture of hexadecane and polyisobutylene was used as the inner solvent phase. This eliminated the need for the deoxygenation step that is essential for existing TTA-based UC processes and enabled stable UC to occur even after a month of exposure to the ambient environment. The photoluminescence properties were examined, and UC-assisted photochemical production of hydroxyl radical from green (532 nm) light irradiation was demonstrated for the first time.

Intensification of biosurfactant synthesis by Acinetobacter calcoaceticus IMV B-7241 on a hexadecane-glycerol mixture

The possibility of enhanced biosurfactant (BS) synthesis by the cultivation of Acinetobacter calcoaceticus IMV B-7241 on a mixture of energetically nonequivalent substrates (hexadecane and glycerol) was shown. Based on theoretical calculations of the energy requirements for biomass production and the synthesis of surface-active trehalose monomycolate from the energy-deficient substrate (glycerol), the concentration of the energy-excessive substrate (hexadecane), which increased the efficiency of the substrate carbon conversion to BS, was determined. The synthesis of extracellular BS on a mixture of hexadecane and glycerol in a molar ratio of 1: 7 at C/N ratio of 30 increased 2.6–3.5-fold compared to that on single-substrate media. Increased BS synthesis by Acinetobacter calcoaceticus IMV B-7241 grown on a hexadecane-glycerol mixture was accompanied by a 1.3–2.4-fold increase in activities of the enzymes involved in their biosynthesis, as well as by simultaneous functioning of two anaplerotic pathways (the glyoxylate cycle and the phosphoenolpyruvate carboxylase reaction).

Phase behavior of tetradecane–hexadecane mixtures confined in SBA-15

Phase behavior of tetradecane–hexadecane mixtures (n-C14H30–C16H34, C14–C16) confined in SBA-15 (pore diameters 3.8, 7.8, and 17.2 nm) has been studied by differential scanning calorimetry. Phase diagram of the confined C14–C16 mixtures is greatly influenced by the pore size, which is simple compared with that for the bulk. Melting points of C14 and C16 confined in SBA-15 display a linear relation with pore size. Meanwhile, the C14–C16 mixtures have shown a similar melting behavior as pure C14 and C16. Melting temperatures of three C14–C16/SBA-15 systems have been fitted as a function of mole fraction xC16.

Synergistic effect of Laponite RD and oil soluble surfactant in stabilization of miniemulsions

Laponite RD was used in combination with the oil soluble surfactant dimethyl-di(hydrogenated tallow)ammonium iodide (2M2HT) for the stabilization of oil-in-water (o/w) miniemulsions. The 2M2HT promoted the adsorption of the Laponite RD at the oil–water interface. Either hexadecane or a mixture of hexadecane and heptane was used as the oil phase. Stable o/w miniemulsions were obtained with a droplet size of 225–300 nm, with mostly a monomodal droplet size distribution. Transmission electron microscopy (TEM) images showed that nanocapsules were formed and burst due to evaporation of hexadecane under the high vacuum conditions of TEM. This provided evidence of the robust nature of the Laponite discs that stabilized the droplets via both mechanical and electrostatic stabilization.

Reforming of Diesel Fuel in a Micro Reactor

Reforming of diesel fuel is challenging but very attractive for hydrogen production. It can facilitate the market entrance of fuel cells due to the existing infrastructure for distribution of diesel fuel. Reforming in micro reactors enables good heat transfer and therefore small and compact fuel processing systems e.g. for electrical energy generation in auxiliary power units.Due to the complexity of diesel, reforming of different diesel components and conversion intermediates in a micro reactor is investigated systematically within this work. Methane and propane were applied as conversion intermediates and hexadecane as a diesel surrogate. All experiments were conducted over a rhodium catalyst on Al2O3 or CeO2.For evaporation of the higher boiling hydrocarbons a micro structured injection nozzle was fabricated to create a fine hydrocarbon spray which evaporates in water vapour. Furthermore a complex gas chromatographic method to analyse hydrocarbons up to C16 and the permanent gases in one analysis run was developed.Experimental results show that the turnover frequency of the fuel molecules in the feed decreases linearly for straight chain hydrocarbons with an increasing number of carbon atoms. Calculations show that the observed conversions and product gas compositions are close to the thermodynamic equilibrium. The catalyst system Rh/CeO2 offers better reforming performance and higher resistance to coking apparently due to less acidic sites compared to Al2O3 and the oxygen storage capacity of CeO2.The ongoing work will examine the reforming behaviour of more model diesel fuel components e.g. mixtures of hexadecane and methylnaphthalene or synthetic diesel fuel. Experiments will be conducted in an optimised micro reformer, which disposes the heating energy by burning e.g. fuel cell off-gases. This also offers the consideration of start up and load changing behaviour.

The effect of high volume fractions of latex particles on foaming and antifoam action in surfactant solutions

Water-Borne coatings usually contain high volume fractions of latex particles together with high concentrations of surfactants. Presence of the latter means that the coatings have an undesirable tendency to foam during dispensing and application. Oil-based antifoams consisting of mixtures of hydrophobic particles and oils are often used to suppress this tendency. The effect of high volume fractions of latex particles on the foam behaviour and antifoam action in solutions of surfactants typically used in water borne coatings is considered. The surfactants were SDS, AOT and Triton X-100 (an ethoxylated octyl phenol). A mixture of hexadecane and hydrophobed silica was used as an antifoam. The effect of latex particles on foam and antifoam behaviour is complex. It can give rise to three effects – depletion of surfactant concentration by adsorption loss, increase in viscosity and stratification stabilisation of thin liquid films by the particles. We show that the first effect appears to dominate in the case of the selected systems. Additional effects due to stabilisation of foam and oil-water-air pseudoemulsion films by latex particles are also found. Antifoam behaviour appears to correlate with pseudoemulsion film stability. Any stabilisation of such films by latex particles is shown to be readily eliminated by the presence of hydrophobed silica particles.