Abstract  Fourier transform near-infrared spectra of Z-9-octadecen-1-ol in CCl4 solutions have been measured to determine the molar absorption coefficients for both the first and second overtones of an OH stretching mode of its monomer. At concentrations below 1.4 x 10(-2) M, the alcohol exists completely in its monomeric form, and from the absorbance-concentration plots, the molar absorption coefficients have been obtained to be 103 and 5.03 dm(3) mol(-1) cm(-1) for the integrated absorbances (band area) of the first and second overtones, respectively.

Abstract  The paper presents physical properties and kinetics data of sodium sulphite solution, pure or with additives that change surface tension and viscosity. Sokrat44 (copolymer of acrylonitrile and acrylic acid) and short-fiber carboxymethylcellulose (CMC) for the Newtonian and long-fiber CMC for the non-Newtonian viscosity enhancement and Ocenol (cis-9-octadecen-1-ol) or polyethylenglycol (PEG) 1000 for surface tension change were used. The kinetics data are presented under the form of dependencies of oxygen absorption rate (measured in stirred cell) on catalyst (Co2+) concentration, oxygen concentration in gas, pH and temperature of the solution. The method based on Danckwerts' plot for the separate determination of mass transfer coefficient k(L) and gas-liquid interfacial area a in gas-liquid dispersions is described using the kinetics data. Problematic features of the method both at low cobalt catalyst concentrations (deceleration of the chemical oxidation of sulphite in presence of viscosity enhancing additives and non-zero concentration of oxygen in the liquid) and at high catalyst concentrations (shrinking of bubbles in dispersion due to high absorption rates) are taken into account. The method is used in Part II for the determination of k(L) in gas-liquid dispersions produced in mechanically agitated vessel and bubble column. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  The production of second-generation biodiesel with triglycerides or their derivatives through hydroprocessing is considered as a promising approach to make transportation fuels. In this study, a series of Ni-based catalysts supported on basic composite oxides (MO-Al2O3, M=Mg, Ca, Ni, Cu, Zn) were prepared for the catalytic deoxygenation of oleic acid in the presence of H-2. Ni/ZnO-Al2O3 exhibited the highest deoxygenation activity and alkane selectivity, which depended on its moderate basicity. Investigations of the reaction conditions, which include reaction time, reaction temperature, H-2 pressure, and Ni loading, suggested that n-heptadecane was the predominant product and its content increased with reaction temperature. The reaction temperature was more important than H-2 pressure in the catalytic deoxygenation of oleic acid. Additionally, the overall reaction pathways for the conversion of oleic acid were proposed based on the product distribution for different durations and reaction rates of stearic acid, 1-octadecanol, and stearyl stearate, in which the oxygen atoms in the oleic acid were mainly removed in the form of CO through a hydrogenation-dehydrogenation-decarbonylation reaction route. If glycerol trioleate was used instead of oleic acid, Ni/ZnO-Al2O3 exhibited a high hydrodecarbonylation activity and selectivity to n-heptadecane.

Abstract  The hydrodeoxygenation of fatty acids derived from vegetable and microalgal oils is a novel process for production of liquid hydrocarbon fuels well-suited with existing internal combustion engines. The hydrodeoxygenation of stearic acid was investigated in a high pressure batch reactor using n-dodecane as solvent over nickel metal catalysts supported on SiO2, gamma-Al2O3, and HZSM-5 in the temperature range of 533-563 K. Several supported nickel oxide catalysts with nickel loading up to 25 wt.% were prepared by incipient wetness impregnation method and reduced using hydrogen. The catalysts were then characterized by BET, TPR, H-2 pulse chemisorption, TPD, XRD, and ICP-AES. Characterization studies revealed that only dispersed nickel oxide was present up to 15 wt.% nickel loading on gamma-Al2O3. The acidity of the supports depends on nickel loading of oxidized catalysts and increases with increasing nickel loading up to 15 wt.%. n-Pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and I-octadecanol were identified as products of hydrodeoxygenation of stearic acid with n-heptadecane being primary product. The catalytic activity and selectivity to products for hydrodeoxygenation of stearic acid depends strongly on acidity of the supports. The maximum selectivity to n-heptadecane was observed with nickel supported gamma-Al2O3 catalyst. A suitable reaction mechanism of hydrodeoxygenation of stearic acid was delineated based on products distribution. The conversion of stearic acid was increased with increasing reaction time, nickel loading on gamma-Al2O3, temperature, and catalyst loading. Complete conversion of stearic acid was accomplished with more than 80% selectivity to n-heptadecane at reasonable reaction temperature of 563 K after 240 min of reaction using 15 wt.% Ni/gamma-Al2O3 catalyst. An empirical kinetic model was also developed to correlate the experimental data. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  Formation of J-aggregates of the amphiphilic merocyanine 3-octadecyl-2-[3,3-dicyano-allyliden]benzoxazolin (S118) in monolayers at the air-water interface has been investigated in the absence and presence of the additives (coaggregates, CA) octadecane, methylstearate, octadecanoic acid, and octadecanol, respectively, in the molar ratio S118/CA = 1:1. The monolayers have been characterized by surface pressure-area and surface potential-area isotherms, and the morphology was studied by Brewster angle microscopy. Chromophore association was investigated by reflection spectroscopy. In the presence of the coaggregate, monolayer stability is increased and the morphology drastically changed, although J- aggregates are formed in all monolayers. Efficient energy transfer in monolayers at the air-water interface from excited S 118 to an amphiphilic merocyanine incorporated in the monolayer as acceptor was detected by fluorescence spectroscopy.

Abstract  Condensed-phosphate templated resins were prepared by a surface template polymerization method using oleylamine as a functional surfactant, oleyl alcohol as a co-surfactant, divinylbenzene as a matrix-forming monomer, and tripolyphosphate, pyrophosphate, and phosphate as templates. When tripolyphosphate-templated resins were prepared by using oleylamine alone as surfactant, a template effect was not observed. However, we successfully templated tripolyphosphate by using, along with oleylamine and oleyl alcohol or polyethylene glycol monooleyl ether (PGME) as a co-surfactant. The thus-prepared templated resin adsorbed the template molecule more effectively than did a nontemplated resin. A resin prepared using oleyl alcohol as a co-surfactant showed a higher adsorptivity than that prepared by using PGME (n = 2, 10). The amount of oleyl alcohol to be used in resin preparation was studied, and a double molar amount of oleylamine was found optimal. We also investigated the adsorption of other anions, such as phosphate, pyrophosphate, and ferrocyanide, on the tripolyphosphate-templated resin. Pyrophosphate and ferrocyanide ions were adsorbed more effectively on the templated resin than on the non-templated. Conversely, tripolyphosphate showed less adsorptivity on the phosphate- and pyrophosphate-templated resins than on the non-templated resin.

Abstract  We have observed dramatic delays in the formation of the liquid-condensed phase of 1-octadecanol thin films on the surface of levitated water drops as the drops evaporate into a flowing gas stream. When the aqueous substrate starts with more than 1.0X10(-4) M EU(3+) (EDTA), the liquid-condensed phase of 1-octadecanol appears, as expected, at a surface concentration equivalent to one monolayer. As we reduce the initial EU(3+) (EDTA) content, higher and higher surface concentrations of 1-octadecanol are reached prior to the appearance of the liquid-condensed phase. At initial concentrations of EU(3+) (EDTA) below similar to 4.0X10(-7) M, the average surface concentration at the liquid-condensed phase change exceeds ten monolayers. Light-scattering data attest to the presence of small, <400 nm radius, 1-octadecanol particles initially dispersed throughout the substrate. We demonstrate that these particles are collected by the shrinking drop surface with minimal diffusion of the particles to the surface.

Abstract  During the two SIR-C/X-SAR missions in 1994, surface film experiments were performed in the German Eight of the North Sea in order to investigate the reduction of the radar backscatter in the presence of biogenic and anthropogenic sea surface films. For this purpose, backscatter measurements were carried out with a 5-frequency/multi-polarisation scatterometer flown on a helicopter. Monomolecular slicks consisting of the same substance (oleyl alcohol) were deployed under different environmental conditions, particularly, at different wind speeds. It was found that, under all wind conditions, the measured damping ratios (i.e., the ratios of the radar backscatter from a slick-free and a slick-covered water surface) increase with increasing Bragg wavenumber. This cannot be explained by Marangoni damping theory (which describes the damping of small sinusoidal water waves by monomolecular slicks). Instead, wind-induced effects, primarily the energy input by the wind into the wave spectrum, have to be taken into account. For the case of high wind speed (12 m/s, where the energy input by the wind is larger than the viscous dissipation), a theoretical model for the damping ratios is developed. The results of this model agree well with the experimental data, in particular, the absence of the Marangoni damping maximum at intermediate Bragg wavenumbers (approx. 100 rad/m) can be explained. Furthermore, the similarities between the radar backscatter reductions measured over biogenic and anthropogenic surface films under high wind conditions are reproduced.

Abstract  Large differences exist in the water vapor (WV) permeance of films made from different lipids (stearic acid [SA], tristearin [TS], stearyl alcohol [St.4], hexatriacontane [HT], beeswax [BW], and acetylated monoglycerides [AG]). Differences in hydrophilic groups in the various lipids tested account for much of these differences. It is also interesting that the WV permeance of films made from BW or BW and AG increased as the relative humidity (RH) gradient was decreased by raising the dry-side RH from 0% to 65 or 80% (wet-side RH always 100%). This behavior is important because edible films intended as barriers to WV transmission will often be exposed to the latter conditions

Abstract  The interaction of deposited metals with monolayer films is critical to the understanding of, and ultimate utility of, the emerging arena of molecular electronics. We present the results of a thorough study of the interaction of vapor-deposited Au and Ag on alkane films attached to Si substrates. Two distinct categories of films are studied: C18 films formed from the hydrosilation reaction of octadecyl trichlorosilane with thin SiO2 layers and C18 films formed from the direct attachment of functionalized alkanes with hydrogen-terminated Si. Two direct attachment chemistries were studied: (Si)(3)-Si-O-C linkages of 1-octadecanol and octadecanal on H-terminated Si(111) and (Si)(3)-Si-C linkages of 1-octadecene on H-terminated Si(111). The reactivity of the films was studied with p-polarized backside reflection absorption spectroscopy (pb-RAIRS), sputter depth profiling X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), and device electrical tests. Independent of direct attachment chemistry, we report the remarkable observation that deposition of Au results in the displacement of the molecular film from the Si interface. In contrast, the directly attached molecular films are robust toward the deposition of Ag. For both metals, the C18 films formed by hydrosilation reactions on SiO2 remain at the interface. The results of monolayer stability with metal are linked to reactions between the metal and substrate. The displacement of the films by Au is attributed to Au insertion in the Si backbonds, in a reaction analogous to silicide formation. The results demonstrate that one must fully take into account the reactivity of the entire system, including substrates, molecular functional groups, and metal electrodes, when considering the robustness of molecules in metal junctions.

Abstract  Molecular self-assembly is a key to wide-ranging nano- and microscale applications in numerous fields. Understanding its underlying molecular level science is therefore of prime importance. This study resolves the angstrom-scale structure of the earliest and simplest self-assembled monolayer (SAM), octadecanol on amorphous-SiO2-terminated Si(001) substrate, and determines the structures temperature evolution. At low temperatures lateral hexagonal order exists, with close-packed, surface-normal molecules. At similar to 12 degrees C above the alkanols bulk melting, a fully reversible disordering transition occurs to a novel stretched liquid phase, laterally disordered, but only similar to 15% thinner SAM than in the crystalline phase. The SAM persists to >= 100 degrees C. A thermodynamic model yields here a headgroup-substrate bond energy similar to 40% lower than on crystalline sapphire, highlighting the importance of the substrates order, and near-epitaxy, for the SAMs ordering and stability.

Abstract  In the present work, the modified polydimethylsiloxane (PDMS) membranes incorporated by oleyl alcohol (OA) were prepared for the first time. The polymeric membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) before and after modification. These membranes were used for the pervaporative separation of phenol from wastewater. The effects of OA loading and feed temperature on the pervaporation performances have been investigated. The influence of ignoring the partial pressure at the permeate side was compared and discussed. The results showed that the OA presence increased phenol flux and separation factor, and decreased water flux greatly with less than 9 wt% OA loading. The highest pervaporation separation index was obtained with 5 wt% OA loading. The driving force of phenol across the membranes was much lower than that of water, and permeation of phenol was much higher than water in nature. It is necessary to discuss and compare the intrinsic properties of different membranes using permeation and selectivity, even though the membranes are tested under the same feed temperature and concentration. The partial pressure of phenol at the permeation side cannot be simply omitted for its great effect on the permeation. Increasing feed temperature will result in the increase of flux and separation factor, but decrease of permeation.

Abstract  Phase change materials applied in the thermal insulation of building or storage system are beneficial to slow down internal temperature fluctuation and decrease energy consumption. Visible temperature change can provide convenience for people's production and life. In this work, the thermochromic delignified wood composite phase change materials (TCDWs) composed of thermochromic (TC) compound and delignified wood (DW) are fabricated by vacuum-assisted impregnation method. Various techniques are applied to characterize mechanical and thermal properties of TCDWs. Results indicate that TCDW5 exhibit suitable phase change temperature, large latent heat, good thermal reliability, as well as excellent thermal stability and mechanical properties. More importantly, TCDW5 have excellent reversible thermochromic ability and visibly show the phase change progress and temperature by color change from dark blue to off-white. The thermal insulation ability of TCDW5 can reduce heat flow and heat exchange between inside and outside environment, maintaining the internal temperature for longer time. The largest absorption capacity of DW is 65%, which is 15% more than that of pristine wood (PW). The excellent reversible thermochromic, thermal and mechanical properties of TCDWs have great potential in thermal energy storage applications including thermal insulation, decoration, furniture, storage and building energy conservation.

Abstract  A new kind of sandwich-like bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth(III) complexes RE(Pc (*))(2) (Pc (*) = Pc(OC8H17)(8), RE=Er, Sm, Tb) are used as film-forming materials. Pure RE(Pc (*))(2) ultrathin films and RE(Pc (*))(2) and octadecanol (OA)/stearic acid (SA) mixed ultrathin films were prepared by the Langmuir-Blodgett (LB) technique. The LB films were characterized by ultraviolet/visible (UV/Vis) spectroscopy and X-ray photoelectron spectroscopy (XPS). The NO2 gas-sensing properties of SM(Pc (*))(2)/OA LB film are studied compared with that of (i-PrO)(4)CuPc LB film by XPS spectra and valence band spectra. It is found that the interaction between SM(Pc (*))(2) LB film and NO2-as is stronger than that between (i-PrO)(4)CuPe LB film and NO2 gas. Experimental results indicate that bis(phthalocyaninato) rare earth(III) complexes show more remarkable sensitivity than monophthalocyanine, which can be used in high-sensitive gas sensor applications. At the same time, the mechanism of sensitivity of SM(Pc (*))(2)/OA mixed LB film to NO, gas is also studied in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract  Experimental studies have been conducted to explore the mechanisms responsible for the dynamic interfacial tension (IFT) behavior in surfactant/model oil systems. Two multi-n-alkylbenzene sulfonates with high purity were selected as model components, and the dynamic IFTs of the two surfactant solutions against a homologous series of alkanes were measured. The effect of n-octadecanol in oil phase on dynamic IFT behavior has been investigated. The experimental results show that there exist two types of the dynamic IFT curves: for one type of curve, the IFT value drops quickly to the stable value, and for the other type, the IFT value passes through a minimum quickly and soon increases to the stable value. The hydrophilic-lipophilic ability of the surfactant plays the most important role in dynamic IFT behavior. The addition of n-octadecanol will result in the appearance of the IFT minimum at hydrocarbons with a larger alkane carbon number, which can strongly support our explanation.

Abstract  pi-A isotherms were studied for mixed monolayers formed from each of two cationic gemini surfactants(dissymmetrical gemini surfactant 12-2-16 and symmetrical gemini surfactant 12-2-12) with octadecyl alcohol (C18H37OH) on air-water interface. The mixed surface excess free energy, Delta G(M)(exc), was analyzed for each mixed monolayer with various mixed molar ratios at different surface pressures under the point of phase separation; to analyze the compatibility of each of the gimini surfactants and the fatty alcohol in the monolayer. The results show that Delta G(M)(exc) changes with the nature of the mixed molecules, mixed molar ratio, and surface pres sure. Mixed monolayers of 12-2-16 and C18H37OH were considered as incompatible because Delta G(M))(exc) > 0 in all mixed molar ratios. While for a system where 12-2-12 is mixed with C18H37OH, the compatibility of the mixed monolayer lies mostly on the mixed molar ratio. The values of Delta G(M)(exc) augment with increasing the C18H37OH molar ratio, changing from a net attractive interaction to a net repulsive interaction between 12-2-12 and C18H37OH with a critical point of C18H37OH molar ratio 0. 65 added in the mixed system. When the mixing system is thermodynamically favored, increasing surface pressure will promote the mixing; In contrast, increasing surface pressure for a repulsive mixed system will be more thermodynamically unfavorable.

Abstract  Fourier-transform infrared attenuated total reflection spectroscopy is used to measure the effective water diffusion coefficients in pure tetradecanol between 313 K and 338 K and in liquid and liquid-solid mixtures of tetradecanol (C14H29OH) and eicosanol (C20H41OH) at 313K. The temperature dependent data in tetradecanol yields an activation energy for diffusion higher than that measured in pure alkanes. This is consistent with the critical role hydrogen bonds play in diffusion. Differential scanning calorimetry and infrared spectroscopy are used to construct the solid-liquid phase diagram for the tetradecanol-eicosanol system. Diffusion measurements in these mixtures are linked to the experimental phase diagram. Water diffusivity in liquid mixtures at low eicosanol concentrations (80 to 100 mol percent tetradecanol) suggests that the measured diffusion coefficient of water is independent of the mixture's bulk viscosity. We find a six-fold decrease in water diffusivity when the solid fraction of the equilibrium mixture increases from zero to thirty percent. The decrease in water diffusivity results from a longer diffusion path length caused by solid portions of the mixture acting as barriers to diffusion. (C) 2014 Elsevier B.V. All rights reserved.

Abstract  The productivity of fermentations is often limited by end product inhibition. This can be avoided by continuous removal of the inhibiting product from the broth. Such in-situ separation can be conveniently accomplished by liquid-liquid extraction. As an example, the continuous fermentation of ethanol by the thermophilic, anaerobic bacterium Clostridium thermohydrosulfuricum is investigated in a 20-1 fermenter with simultaneous in-situ extraction by oleyl alcohol as organic solvent. Continuous fermentations with and without in-situ extraction were carried out with systematic variation of the independent operating conditions, viz. feed glucose concentration, broth flow rate and solvent flow rate. The experimental results of 18 steady states are reported. They show that in-situ extraction doubles the yield, selectivity and space-time yield of ethanol in comparison to fermentations without in-situ extraction. A biomodel elucidates the influence of feed glucose concentration, broth flow rate and solvent flow rate on the productivity of the fermentation process. Finally, a cost model was developed for the investigated fermentation which allows economic evaluation of the results of experiments and simulation. A sensitivity study elucidates the economic limits and advantages of fermentation with in-situ extraction compared to a common fermentation without product separation.

Abstract  The influence of a thin spreading solvent film (ethanol, diethyl ether, and three fractions of petroleum ether boiling at 30-60 A degrees C, 60-90 A degrees C, and 90-120 A degrees C) on the properties of hexadecan-1-ol (C(16)H(33)OH) monolayers at the air-water interface was studied. The specific evaporation resistance and the surface pressure were determined to describe the spreading behavior of the C(16)H(33)OH monolayers. The physical properties of the solvents and the images obtained in an atomic force microscope were examined. The time of establishing the equilibrium spreading surface pressure of monolayers can be reduced using a more volatile solvent with a lower boiling point and a lower relative density. The influence of the monolayer nature on water evaporation corresponds to the order of changing the solvent spreading rate: petroleum ether (30-60 A degrees C) > diethyl ether > ethanol > petroleum ether (60-90 A degrees C) > petroleum ether (90-120 A degrees C). The monolayers formed upon petroleum ether (30-60 A degrees C) spreading form a film with a less deficient and relatively planar surface. When ethanol is used as a spreading solvent, water evaporation is accelerated rather than retarded, while petroleum ether (30-60 A degrees C) is more appropriate for this purpose.

Abstract  A new SECM approach for studying the lateral diffusion of redox-active amphiphiles in Langmuir monolayers at an air/water (A/W) interface is described. To apply this technique practically, a triple potential step transient measurement is utilized at a submarine ultramicroelectrode (UME) placed in the water phase close (1-2 mum) to the monolayer. In the first potential step, an electroactive species is generated at the UME by diffusion-controlled electrolysis of a precursor. This species diffuses to, and reacts with, the redox-active amphiphile at the A/W interface resulting in the formation of the initial solution precursor, which undergoes diffusional feedback to the UME. In this first step, the rate constant for electron transfer between the solution mediator and the surface-confined species can be measured from the UME current-time transient. In the second period, the potential step is reversed to convert the electrogenerated species to its initial form. Lateral diffusion of electroactive amphiphile into the interfacial zone probed by the UME occurs simultaneously in this recovery period. In the third step, the potential is jumped in the same direction as for the first step and the corresponding UME current-time transient can be used to determine either the distance between the UME tip and the monolayer at the water surface, or the lateral diffusion coefficient of the amphiphile. A theoretical treatment for this technique is developed and discussed in detail. The method is demonstrated experimentally with measurements of the lateral diffusion of N-octadecylferrocenecarboxamide in a 1:1 Langmuir monolayer with 1-octadecanol.

Abstract  Some experimental results on the separation of a peptide from a mixture of peptide and amino acid through a continuous supported liquid membrane process are described. As a model system a mixture of tryptophan (Trp, an amino acid) and tryptophan-leucine (Trp-Leu, a dipeptide) was chosen. The liquid membrane contained an anionic surfactant, sodium di-2-ethylhexyl sulfosuccinate (Aerosol OT/AOT), as a carrier dissolved in oleyl alcohol, as an organic solvent, supported on a commercial grade support (Celgard 2500). The liquid-liquid extraction experiments were carried out to study the influence of feed pH, feed and strip flow rates, and feed and carrier concentrations on the selective transport of Trp-Leu from its mixture with Trp. At pH 4-5 the transport rate of Trp-Leu was significantly higher than that of Trp. The increase in flow rate up to a value of 40 mL/h did not effect the selective removal of Trp-Leu. The flux rate increased with an increase of the carrier concentration up to 20% AOT, but the selectivity for Trp-Leu was highest at 10% AOT. An increase of Trp concentration up to 10-fold had little effect on the flux rate of Trp-Leu. The stability of SLM system in continuous removal of Trp-Leu from a single component system and from a binary mixture with Trp was studied. The effect of a competitive component did not alter significantly the flux rate and long-time performance in continuous operation. A procedure for regenerating SLM was examined, and the regenerated SLM performed as good as the freshly prepared one.

Abstract  Liquid membranes prepared using an anionic surfactant (Aerosol OT) as carrier and oleyl alcohol. as organic solvent loaded on a commercial support (Celgard 2500) were evaluated for extraction of amino sugars, amino acids and dipeptides from solution at laboratory and pilot scale. Feed pH influenced extraction of amino acids and peptides but had little effect with amino sugars. Increase in carrier concentration improved extraction of amino sugars but not amino acids and peptides. The pilot hollow-fibre membrane extracted about 90% of solutes in eight hours.

Abstract  The polymer beds described are synthesized in aqueous solution directly in the column or batchwise in the form of large clusters of small particles. The conventional, expensive step involving prepreparation of beads in an organic solvent is thus omitted. Beds were synthesized from piperazine diacrylamide, methacrylamide and allyl glycidyl ether. The epoxy-activated beds thus obtained were used for covalent attachment of either nonpolar ligands (e.g. octadecanol) or polar OH-rich substances (e.g. dextran). The non-polar beds were used for reversed-phase chromatography, as were polar ones following coupling with 1,2-epoxyoctadecane. Coating with OH-rich substances serves two purposes: (1) the matrix becomes hydrophilic, decreasing nonspecific interactions (modifiers can be excluded) and hence increases resolution and (II) many - OH groups are available (e.g. for coupling to epoxides), a prerequisite for high ligand density. Resolution of proteins was high even at high flow rates. Depending on the method used for the synthesis of the bed, resolution of proteins either increased with an increase in flow rate or decreased slightly. Choice of the correct temperature was very important for high resolution of CNBr-digested peptides.

Abstract  The extraction of amino acids (tryptophan (Trp), phenylalanine (Phe) and dipeptides (tryptophan-leucine (Trp-Leu), phenylalanine-leucine (Phe-Leu)) is examined by passing a "feed" solution (an aqueous solution containing any of the target solutes) through the fiber-side of an extra-flow hollow-fiber membrane module (HFMM). The membrane module (2.5 cm diameter x 20 cm long) has a shell-and-tube configuration and allows flow of two solutions in the fiber and shell sides. The extraction solution contained an ionic carrier, Aerosol OT (AOT), dissolved in a solvent, oleyl alcohol. The feed and organic solutions were circulated on the fiber side and shell side, respectively. The target solute (any of the amino acids or peptides) diffuses to the interface, forms a complex with the carrier; the carrier-solute complex is transported to the shell side, where it can be recovered. A mathematical model that includes the equilibrium distribution at the interfaces and the convective flow in the module is presented. A straightforward use of the experimental data has been shown to be able to calculate the overall mass transfer coefficient of the extraction process. The value of the overall mass transfer coefficient is similar to those in the literature and has been found to be significantly affected by the solute type and feed solution pH. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  Problems preparing paraffin wax emulsions stabilized by different types of emulsifiers have been discussed. The effect of the preparation conditions and stabilizers, such as polyethylene glycol and cetyl/oleyl alcohol ether (Eumulgin O10), polyvinyl alcohol, and SiO2@Al2O3 nanoparticles (20 nm in diameter) on the dispersion of paraffin wax emulsions has been demonstrated. It has been noted that, in order to obtain paraffin wax particles with an average diameter of 400-500 nm, the concentration of PVA, Eumulgin O10, and SiO2@Al2O3 nanoparticles must be equal to 0.5, 0.5, and 1.0 wt %, respectively.