Hexadecane Research Articles

Establishing the importance of oil-membrane interactions on the transmembrane diffusion of physicochemically diverse compounds

The diffusion process through a non-porous barrier membrane depends on the properties of the drug, vehicle and membrane. The aim of the current study was to investigate whether a series of oily vehicles might have the potential to interact to varying degrees with synthetic membranes and to determine whether any such interaction might affect the permeation of co-formulated permeants: methylparaben (MP); butylparaben (BP) or caffeine (CF). The oils (isopropyl myristate (IPM), isohexadecane (IHD), hexadecane (HD), oleic acid (OA) and liquid paraffin (LP)) and membranes (silicone, high density polyethylene and polyurethane) employed in the study were selected such that they displayed a range of different structural, and physicochemical properties. Diffusion studies showed that many of the vehicles were not inert and did interact with the membranes resulting in a modification of the permeants’ flux when corrected for membrane thickness (e.g. normalized flux of MP increased from 1.25±0.13μgcm−1h−1 in LP to 17.94±0.25μgcm−1h−1in IPM). The oils were sorbed differently to membranes (range of weight gain: 2.2±0.2% for polyurethane with LP to 105.6±1.1% for silicone with IHD). Membrane interaction was apparently dependent upon the physicochemical properties including; size, shape, flexibility and the Hansen solubility parameter values of both the membranes and oils. Sorbed oils resulted in modified permeant diffusion through the membranes. No simple correlation was found to exist between the Hansen solubility parameters of the oils or swelling of the membrane and the normalized fluxes of the three compounds investigated. More sophisticated modelling would appear to be required to delineate and quantify the key molecular parameters of membrane, permeant and vehicle compatibility and their interactions of relevance to membrane permeation.

Rapid and Efficient Separation of Oil from Oil-in-Water Emulsions Using a Janus Cotton Fabric.

A novel bi-functional Janus cotton fabric is used to separate oil from oil-in-water emulsions. This fabric is superhydrophobic on one surface and polyamine-bearing on the other. When used as a filter, the polyamine-bearing side causes the micrometer-sized oil droplets to coalesce. The coalesced oil then fills fabric pores on the superhydrophobic side and selectively permeates it. Oil separation using this method is rapid and the separated oil is pure. Furthermore, the content of the model oil hexadecane (HD) in water after a separation can be reduced to less than 0.03±0.03 vol%. These features demonstrate the practical potential of this technology.

Rapid and Efficient Separation of Oil from Oil‐in‐Water Emulsions Using a Janus Cotton Fabric

AbstractA novel bi‐functional Janus cotton fabric is used to separate oil from oil‐in‐water emulsions. This fabric is superhydrophobic on one surface and polyamine‐bearing on the other. When used as a filter, the polyamine‐bearing side causes the micrometer‐sized oil droplets to coalesce. The coalesced oil then fills fabric pores on the superhydrophobic side and selectively permeates it. Oil separation using this method is rapid and the separated oil is pure. Furthermore, the content of the model oil hexadecane (HD) in water after a separation can be reduced to less than 0.03±0.03 vol %. These features demonstrate the practical potential of this technology.

Phenanthrene Metabolites from a New Polycyclic Aromatic Hydrocarbon-Degrading Bacterium Aeromonas salmonicida subsp. Achromogenes Strain NY4

A new polycyclic aromatic hydrocarbon (PAH)-degrading Gram-negative bacterium Aeromonas salmonicida subsp. achromogenes strain NY4 was isolated from coking wastewater sludge. Strain NY4 could not grow on1-hydroxy-2-naphthoic acid, hexadecane or hexanol as sole carbon source but phenanthrene. This strain was able to utilize several known microbial metabolites of PAHs, including catechol, protocatechuic acid, salicylic acid, and phenol as sole carbon source. The mixture of the acidic and neutral fraction, acidic fraction alone and neutral fraction alone of phenanthrene metabolites were prepared and analyzed by GC-MS. A total of at least 27 metabolites were identified as the degradation products of phenanthrene by strain NY4. Among them, 1-hydroxy-α-oxo-2-naphthaleneacetic acid, 2-hydroxy-α-oxo-1-naphthaleneacetic acid, 2-hydroxy-1-(1-hydroxy-2-naphthalenyl)-ethanone, 1,2-dihydro naphtha [2,1-b] furan-2-ol and 2,3-dihydro naphtha [1,2-b] furan-2-ol have not been reported as the metabolites of phenanthrenes s...

Development of eukaryotic zoospores within polycyclic aromatic hydrocarbon (PAH)-polluted environments: A set of behaviors that are relevant for bioremediation

In this study, we assessed the development (formation, taxis and settlement) of eukaryotic zoospores under different regimes of exposure to polycyclic aromatic hydrocarbons (PAHs), which imitated environmental scenarios of pollution and bioremediation. With this aim, we used an oomycete, Pythium aphanidermatum, as a source of zoospores and two PAH-degrading bacteria (Mycobacterium gilvum VM552 and Pseudomonas putida G7). The oomycete and both bacteria were not antagonistic, and zoospore formation was diminished only in the presence of the highest bacterial cell density (108–1010colony-formingunitsmL−1). A negative influence of PAHs on zoospore formation and taxis was observed when PAHs were exposed in combination with organic solutions and polar solvents. Co-exposure of PAHs with non-polar solvents [hexadecane (HD) and 2,2,4,4,6,8,8-heptamethylnonane (HMN)] did not affect zoospore settlement at the interfaces of the organic solvents and water. However, zoospores settled and created mycelial networks only at HD–water interfaces. Both bacteria diminished the toxic influence of PAHs on zoospore formation and taxis, and they did not interrupt zoospore settlement. The results suggest that zoospore development could be applicable for toxicity assessment of PAHs and enhancement of their bioavailability. Microbial interactions during both swimming modes and community formation at pollutant interfaces were revealed as major factors that have potential relevance to bioremediation.

Electric field as pretreatment to enhance the activity of a whole-cell biocatalyst for hydrocarbon degradation in contaminated water

Abstract In this paper, a method using two successive cultures, solid then liquid, for the production and use of a hydrocarbon degrading biocatalyst (BC) is proposed. Hexadecane (HXD) was used as a model hydrocarbon. An electric field was applied during the solid state culture (SSC) as a novel approach, denoted the electric field pretreatment, to enhance the HXD degrading activity. Afterward, the catalytic activity (CA) was determined in liquid culture. The CA of the biocatalyst pretreated and untreated was evaluated, discriminating between sorption capacity and HXD degradation rate; biomass production on the electric field pretreated biocatalyst was only 20% of that on the untreated biocatalyst, but the maximum biocatalyst sorption capacity was enhanced from 119 ± 41 mg (g BC)−1 to 207 ± 23 mg (g BC)−1 by the effect of the electric field pretreatment. The activity of the biocatalyst was mainly associated with the pretreated fungal biomass; its activity was 9-fold higher than that of the untreated biomass. Linear model was used to obtain the affinity constant and Langmuir to adjust maximum sorption capacity. This enhancement in sorption capacity was associated with the high HXD degradation rate observed here; 86% of the initial HXD was eliminated in 42 h by the pretreated biocatalyst, whilst 53% was eliminated in 48 h by the untreated biocatalyst.

Evolution of droplet size distribution and composition in miniemulsions

ABSTRACTA fundamental understanding of the formation, degradation and polymerization of miniemulsions has been hindered by difficulties in quantifying their monomer droplet size distribution (DSD). In this work, particle sizing techniques including capillary hydrodynamic fractionation, acoustic attenuation spectroscopy, surfactant titration, and microscopy were adapted to characterize miniemulsion DSDs. The key ingredient in miniemulsions is the costabilizer, a low water solubility compound that limits monomer diffusion from the smaller to larger droplets (Ostwald ripening). The DSD evolution of styrene miniemulsions employing hexadecane (HD) as costabilizer was characterized. With less costabilizer, droplets were initially smaller, but increased in average size with time, and their DSDs broadened. These changes were slowed with addition of extra surfactant after homogenization. After several days, the average droplet size increased to about 150 nm regardless of the amount of HD or surfactant used. The HD content of separated portions of centrifuged miniemulsions was measured and showed significant Ostwald ripening within minutes after preparation. The further evolution of the DSD is attributed primarily to droplet coalescence. Less composition change occurred with either higher HD content or post‐homogenization surfactant addition, both of which led to minimization of free energy, increasing stability. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1529–1544

Thermal Expansion of Free-Volume in Hexadecane Confined in the Silica Gel Nanopores

Temperature dependence of the free-volume of voids in hexadecane (HXD) con ned in the 3 nm silica gel pores (Develosil-30) was measured by positron annihilation lifetime spectroscopy. Di erent amount of HXD was lled into the pores of matrix. The anomalous thermal expansion was observed in the partially lled pores with extremely low lling. The thermal expansion coe cient of free-volume voids in this solidi ed HXD layer has a negative sign at temperatures below 180 K compared to highor fulllled pores of silica gel. At these temperatures, the positron annihilation lifetime spectroscopy measurements demonstrate the appearance of a new type of the free volume within HXD which has been interpreted as the cracks in the HXD layer on the inner walls of matrix cavities. The di erential scanning calorimetry method con rmed that the processes were enacted within pores and not on the outer surfaces of silica gel grains. In the sample with the extremely low lling, only the one HXD solidi cation/melting e ect connected with con ned states is manifested.

Synthesis and Evaluation of Poly(Sodium 2-Acrylamido-2-Methylpropane Sulfonate-co-Styrene)/Magnetite Nanoparticle Composites as Corrosion Inhibitors for Steel

Self-stabilized magnetic polymeric composite nanoparticles of coated poly-(sodium 2-acrylamido-2-methylpropane sulfonate-co-styrene)/magnetite (PAMPS-Na-co-St/Fe3O4) were prepared by emulsifier-free miniemulsion polymerization using styrene (St) as a monomer, 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na) as an ionic comonomer, N,N-methylenebisacrylamide (MBA) as crosslinker, hexadecane (HD) as a hydrophobic solvent, and 2,2-azodiisobutyronitrile (AIBN) as an initiator in the presence of hydrophobic oleic acid coated magnetite particles. Hydrophobic oleic acid coated magnetite particles with an average size of about 7-10 nm were prepared with the new modified water-based magnetite ferrofluid, synthesized by a chemical modified coprecipitation method. The morphology and the particle size distributions of the crosslinked PAMPS-Na-co-St/Fe3O4 composite were observed and analyzed by transmission electron microscopy (TEM). The average Fe3O4 content of PAMPS-Na-co-St/Fe3O4 was determined by thermogravimetric analysis (TGA). The inhibitory action of PAMPS-Na-co-St/Fe3O4 towards steel corrosion in 1 M HCl solutions has been investigated by polarization and electrochemical impedance spectroscopy (EIS) methods. Polarization measurements indicate that PAMPS-Na-co-St/Fe3O4 acts as a mixed type-inhibitor and the inhibition efficiency increases with inhibitor concentration. The results of potentiodynamic polarization and EIS measurements clearly showed that the inhibition mechanism involves blocking of the steel surface by inhibitor molecules via adsorption.

Hollow spherical micro/meso-porous silica structure by nanospherical sacrificial polystyrene templates

In this study, spherical polystyrene (PS) nanoparticles having a negative surface charge were synthesized by polymerization of a miniemulsion containing styrene monomer, normal hexadecane (HD) as hydrophobic agent, sodium dodecyl sulfate (SDS) as anionic emulsifier, sodium bicarbonate (NaHCO3) as buffer, and water soluble potassium persulfate (KPS) as initiator. The effects of three important parameters (surfactant, cosurfactant, and initiator) on particle size and size distribution were contemporaneously investigated. The particle size and size distribution was measured using dynamic light scattering (DLS). Transmission electron microscopy (TEM) images were also taken from the corresponding latexes to confirm the results. The produced polystyrene particles were coated by silica via sol-gel process in which tetraethyl orthosilicate (TEOS) precursor, ethanol, hydrochloric acid, and water were employed to carry out hydrolyzation/condensation process. Using ultra-high speed centrifugation, a closely packed assembly of particles resulted which were subjected to calcination process to form hallow spherical micro/meso-porous silica structure. The average pore diameters of the micro and meso pores were 2–3 nm and 25–30 nm, respectively, as determined by nitrogen sorption isotherms. The specific surface of the porous sample was also measured by Brunauer, Emmett, and Teller (BET) method to be 554.74 m2/g that is well suited for catalyst support applications. In the end, the produced catalyst support was used to form ziegler-natta catalyst. By using the produced catalyst via prepolymerization and slurry polymerization at 70℃, polypropylene was polymerized from propylene.

Preparation of cellulose particles using an ionic liquid

Cellulose is a ubiquitous natural fiber used in various industrial materials and applications. We prepared micron-sized cellulose particles by the solvent releasing method (SRM) in which cellulose–[Bmim]Cl–N,N-dimethylformamide (DMF) droplets are dispersed in hexadecane (HD) containing dissolved surfactant. The dispersion is then poured into a large amount of 1-butanol. Since 1-butanol is miscible with HD, [Bmim]Cl, and DMF but not with cellulose, the cellulose particles precipitate out. FTIR and 1H NMR analyses confirmed that this technique precipitated cellulose and completely removed [Bmim]Cl and DMF from the cellulose–[Bmim]Cl–DMF droplets. Interestingly, the obtained cellulose particles were almost the same size as the original droplets (cellulose, 7wt%), indicating a microporous structure of the cellulose particles with a large medium content. Although the microporous structure collapsed as the medium evaporated, it was maintained by a freeze-drying technique.

Optimization of parameters in preparation of PCM microcapsules based on melamine formaldehyde through dispersion polymerization

Microencapsulated phase change materials have attracted special attention due to their wide applications in saving and releasing energy. Here, microencapsulation of hexadecane (HD) in melamine formaldehyde shell was carried out through in situ dispersion polymerization in the aqueous media. Some important parameters such as stabilizer type and amount, surfactant amount, homogenization conditions as the critical affective factors on final particle size, morphology, and thermal resistance of the microcapsules were investigated extensively. The obtained microcapsules were concurrently analyzed by SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques. SEM images showed that the best stabilization was achieved by polyvinyl alcohol. Also, particle size, as an indication of surface area for heat transfer properties, showed a decrement by increasing stabilizer amount, surfactant amount, and homogenization speed. The amount of entrapped HD and efficiencies of microencapsulation were determined by DSC, and the reason for observing such changes were discussed in detail. Thermal stability of the microcapsules as an important property for their performance was investigated, too. The results illustrated that an improved thermal stability would be obtained by an efficient stabilization in the emulsification step. Also the highest thermal stability up to 388 °C was reached at homogenization speed of 6,000 rpm. Finally, the optimized conditions for desirable encapsulation were proposed in such systems.

The role of catalyst in supercritical water desulfurization

We evaluated supercritical water (SCW) for sulfur removal from Arabian Heavy (AH) whole crude oil and two model feeds: hexyl sulfide (HS) in hexadecane (HD) and dibenzothiophene (DBT) in HD. We measured SCW desulfurization performance in the absence and presence of ZnO, MoO3 and MoS2. No external hydrogen source, aside from water and oil itself, was added to the reaction mixture. SCW alone (without a catalyst) removes 6–7% of the sulfur present in AH, and addition of MoS2 improves the sulfur removal by a factor of 2 (to ∼12%). For the HS-HD model feed, we found that HS conversion in SCW alone is high (∼85%) and is weakly affected by addition of catalysts. Hence, we infer that catalysts have minimal effect on the decomposition rates of aliphatic sulfide compounds. Addition of any of the three catalysts improved the decomposition of DBT in the HD model feed, with ZnO providing the strongest effect (from 3 to 25%). Furthermore, ZnO and MoO3 catalysts promoted total sulfur removal, indicating a reduction in the formation of secondary sulfur compounds in the presence of oxide catalysts. We characterized the bulk and surface properties of fresh and SCW-exposed catalysts for treatment of the HS-HD model system using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectrometry (XPS). As anticipated, MoS2 remained unchanged during the SCW treatment, whereas MoO3 and ZnO underwent structural and morphological changes primarily related to sulfidation reactions. The results of this work help establish the role of catalysts in the SCW process; demonstrate that modest desulfurization can be achieved in the absence of an external hydrogen source; and provide guidelines for catalyst selection.

Hexadecane aqueous emulsion characterization and uptake by an oil-degrading microbial consortium

In the present work was characterized in abiotic and biotic systems, the droplet size of hexadecane (HXD) in emulsified form. Furthermore it was assessed the uptake of HXD in their both form emulsified (microscopic droplets) and free (macroscopic droplets), using a microbial consortium with the capacity of degrading oil. HXD in emulsified form includes microscopic droplets of 0.1 and 0.5 up to 0.7 μm. In the biotic experiments the kinetic parameters values were determined either by fitting to the Contois model the consumed data of HXD emulsified and by considering also the uptake rate of the free forms of HXD as independent of their own concentration. A comparison of the maximum specific HXD uptake rate (qmax) of the oil-degrading consortium when consumes the two forms of HXD, shows to be 53 times greater for the emulsified HXD that for their free form, suggesting that consumption of HXD is realized mostly by the emulsified form. The specific transfer area decreases with the culture time due to that the HXD is emulsified and consumed by the microbial consortium, being the specific transfer area of emulsified forms (microscopic droplets) a parameter that must be considered in the design of biodegradation processes of insoluble organic pollutants.

PALS and DSC study of nanopores partially filled by hexadecane

The controlled porosity glasses (CPG) filled with various amount of hexadecane (HXD) in nanopores were studied both by the positron annihilation lifetime spectroscopy (PALS) and the differential scanning calorimetry (DSC) methods. Two types of CPG matrices were used with average pore sizes 12.6 and 22.2 nm. The PALS measurements showed, that when the process of large pores filling by HXD has started, the long o-Ps lifetime went down to HXD o-Ps lifetime about 3ns [1]. DSC measurements at partially filled nanopores showed always two crystallization peaks [2]. Their positions depended on average pore size of matrix. Third crystallization peak was identified in overfilled samples (only short o-Ps lifetimes were present) and their position in temperature scale was the same as for the bulk HXD peak. The latter peak was independent of the average pore size of matrices. This fact confirms the assumption that processes studied by PALS with the samples that contained smaller amount of HXD in CPG occured inside of nanopores of the matrix.

Synthesis of Nanoscale Binders through Mini Emulsion Polymerization for Textile Pigment Applications

Different mini emulsion polymerizations were carried out with the combination of different concentration of anionic surfactant such as sodium dodecyl sulfate (SDS) or hydrophobic alkane such as (hexadecane), and/or different monomer ratios. The best comonomers composition that would lead to the best polymer latex properties to obtain nanoscale polymer latexes was studied. The polymer latexes in a size range between 156 and 65 nm by varying the SDS concentrations from 2 to 6 wt % were obtained, and also the particle size of the obtained polymer latexes decreases with the increases of hexadecane (HD) concentrations, and the best result was obtained with 4 wt % of a hexadecane. The best polymer latex properties in terms of particle size and binder softness were found in the best monomer ratio of BA:MMA:MAA (17.5:1.5:1.5) as the solid content was adapted to be 20%. Higher K/S values and improved crocking fastness are obtained with printing pastes containing prepared binder.

Preparation of disperse dye/latex dispersion for printing of cellulose fabric

A dispersion was prepared from disperse dye and latex composite (disperse dye/latex composite) by the method of miniemulsion polymerization. Different types of costabilizers, emulsifiers and initiators were tested for optimizing miniemulsion polymerization which was critical to achieve high-performance dispersion for printing of cellulosic fabric. Experimental results showed that hexadecane (HD), allyloxy nonylphenol polyoxyethylene ether ammonium sulfate (DNS-86) and ammonium persulfate (APS) were suitable for use as costabilizer, emulsifier and initiator in miniemulsion polymerization. An optimal dispersion was obtained by using 14.4mmolL−1 DNS-86, a 1:100 mass ratio of HD to styrene and a 7.5:100 mass ratio of APS to styrene. Fourier-transform infrared spectroscopy (FTIR) suggested that copolymerization took place between DNS-86 and styrene. Transmission electron microscopy (TEM) showed that the spherical particles were formed and uniformly distributed in the dispersion. Printing cellulose fabric with the disperse dye/latex composite produced higher color strength and color fastness than the original disperse dye.

Influence of Rice Cultivars on the Parasitization Efficiency of Trichogramma chilonis Ishii and Trichogramma japonicum Ashmead

Trichogrammatids are efficient egg parasitoids in rice agroecosystem and two species of Trichogramma viz., Trichogramma chilonis Ishii and T. japonicum Ashmead were reported from several species of rice stem borers and other lepiodpterous pests. Physicochemical variations between the cultivars of crops often interfere with the efficiency of the Trichogramma spp. The response of T. chilonis and T. japonicum to the variations in the volatile profile of rice cultivars was investigated. The results indicated that the parasitization efficiency of both T. chilonis and T. japonicum was influenced by the volatiles of rice cultivars. While in some cultivars, such as Kadamba, MTU-1010, KMT 148, KCP-1, the response of T. chilonis was very high, in some of the cultivars like CTH-1, MTU 1010, VTT-5204, the response by T. japonicum was high. The highest overall response of 83.89 % was recorded in the variety Kadamba by T. chilonis . Volatile profile of the cultivars indicated the presence of 9,12,15 octadecatrienoic acid and 9-octadecenal might have played positive role in the attraction of T. chilonis to specific cultivars while hexadecane, heptadecane, petadecane and hexadeconic acid might be responsible for the attraction of T. japonicum .

Comparison of mechanisms of hexadecane uptake among pure and mixed cultures derived from a bacterial consortium

Members of a bacterial consortium were isolated from an oil-contaminated site in Veracruz, Mexico and identified as Xanthomonas sp., Acinetobacter bouvetii, Shewanella sp. and Defluvibacter lusatiensis. We compared mechanisms of hexadecane (HXD) uptake by pure and mixed cultures based on cell surface hydrophobicity (CSH), biosurfactant production and emulsification capacity. HXD was removed by the pure cultures of A. bouvetii (72 ± 4%), Xanthomonas sp. (46 ± 4%) and D. lusatiensis (40 ± 6%), but not by Shewanella sp. Mixed cultures showed an enhanced HXD removal, particularly with the whole consortium (79 ± 3%) and when Xanthomonas sp. and A. bouvetii were combined (74 ± 7%). A. bouvetii was the only biosurfactant producer. Based on removal abilities, the uptake mechanisms were evaluated for A. bouvetii and the consortium. Our findings indicated that A. bouvetii combined both direct contact and biosurfactant-mediated uptake. For the consortium the two uptake mechanisms took place; however, the emulsification was predominant after 5 days. Differences in the uptake mechanisms by tested cultures suggested that the prevalence of one or another mechanism depends on changes in the CSH, the emulsification extent and associations among strains. Our results contribute to understand the HXD uptake mechanisms by pure and mixed cultures and reveal A. bouvetii as a potential biosurfactant producer.

Multi-Phase Composite Nanofibers via Electrospinning of Latex Containing Nanocapsules with Core-Shell Morphology

Nanocapsules containing hexadecane (HD) as core material and polystyrene (PS) as shell, were electrospun with polyethylene oxide (PEO) as a matrix material into the fiber webs. The morphology and thermal properties of PEO fibers containing (1) both PS nanocapsules with core-shell morphology and solid PS particles, (2) only solid PS particles, and (3) without any PS particles, were compared and the effect of PEO concentration on morphology of the resultant fibers have been studied. The resultant fibers were characterized by means of Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Both TEM observation and DSC analyses confirmed that the PS nanocapsules were encapsulated within the PEO nanofibers. The fibers had an average diameter of 950 nm for nanocapsules containing parts, 300 nm for solid particles containing parts, and 150 nm for usual parts. The phase change temperatures and phase transition heat of the produced fibers were determined by DSC analyses. TGA was also used to confirm the preparation of multi phase fibers and to determine the amount of HD within the fibers.