Water-free System Research Articles

Enzymatic Synthesis of Structured Lipids Enriched with Medium- and Long-Chain Triacylglycerols via Pickering Emulsion-Assisted Interfacial Catalysis: A Preliminary Exploration.

Medium- and long-chain triacylglycerol (MLCT), as a novel functional lipid, is valuable due to its special nutritional properties. Its low content in natural resources and inefficient synthesis during preparation have limited its practical applications. In this study, we developed an effective Pickering emulsion interfacial catalysis system (PE system) for the enzymatic synthesis of MLCT by trans-esterification. Lipase NS 40086 served simultaneously as a catalyst and a solid emulsifier to stabilize the Pickering emulsion. Benefitting from the sufficient oil-water interface, the obtained PE system exhibited outstanding catalytic efficiency, achieving 77.5% of MLCT content within 30 min, 26% higher than that of a water-free system. The Km value (0.259 mM) and activation energy (14.45 kJ mol-1) were 6.8-fold and 1.6-fold lower than those of the water-free system, respectively. The kinetic parameters as well as the molecular dynamics simulation and the tunnel analysis implied that the oil-water interface enhanced the binding between substrate and lipase and thus boosted catalytic efficiency. The conformational changes in the lipase were further explored by FT-IR. This method could give a novel strategy for enhancing lipase activity and the design of efficient catalytic systems to produce added-value lipids. This work will open a new methodology for the enzymatic synthesis of structured lipids.

Effect of water on dynamics of HOCO radical

The activated HOCO* is one of the most important intermediates in combustion and atmospheric processes and could become thermally stabilized through the collision with the third species. In this work, the effect of a single water molecule on an energized HOCO* radical for the collision of HOCO + H 2 O has been investigated by using direct dynamics methodology. The properties of the stationary points on the potential energy surface have been characterized at M06-2X/aug-cc-pVDZ level of theory. Interesting dynamical features and detailed atomic level mechanisms are presented. It is found that the water molecule is not involved in the chemical reaction, but it can substantially decrease the activation barrier when compared with the water-free system. Energy distributions of products indicate that H 2 O can transfer the vibrational energy of the energized HOCO to its own rotational energy and thus serves as an efficient third body.

Efficient separation of tocopherol homologues in vegetable oil by ionic-liquid-based countercurrent chromatography using a non-aqueous biphasic system.

Tocopherol homologues are important fat-soluble bioactive compounds with high nutritional value. However, it is of great challenge to separate these homologues because of their high structural similarities. In this work, ionic-liquid-based countercurrent chromatography was used for the separation and purification of tocopherol homologues. Conventional countercurrent chromatography and ionic-liquid-based countercurrent chromatography solvent systems were evaluated in respect of partition coefficient, separation factor, and stationary phase retention factor to separate these targets. Kind of ionic liquids, amount of ionic liquid, and sample amount were systematically optimized. A novel countercurrent chromatography non-aqueous biphasic system composed of n-hexane-methanol-1-butyl-3-methylimidazolium chloride was established. The baseline separation of tocopherol mixtures was obtained in one cycle process. The ionic liquid played a key role in the countercurrent chromatography separation, which resulted in difference of partition behavior of individual tocopherol in the whole system through different hydrogen-bonding affinity. Finally, n-hexane-methanol-1-butyl-3-methylimidazolium chloride (5:5:3, v/v) water-free biphasic system was successfully applied to separate tocopherol homologues from vegetable oil that was not achieved beforehand. This method can be widely employed to separate many similar molecules such as tocotrienols, tocomonoenols, and marine-derived tocopherol in food samples.

Reversible Structure Formation of Aluminum Trihydroxide (ATH) Dispersions in Polydimethylsiloxane (PDMS).

Aluminum trihydroxide/polydimethylsiloxane (ATH/PDMS) systems are often used as potting compounds in electronic assemblies to guard the electronics from shock, vibration, corrosive agents, and moisture. In this study, we use dynamic rheology and confocal/optical microscopy to understand the dramatic effects miniscule levels of water have on the microstructure and corresponding rheological behavior of PDMS filled with ATH. In the absence of water, PDMS containing 20 wt % ATH readily flows, exhibiting viscoelastic behavior with some weak particle flocculation. However, the addition of only 0.045 wt % water to the system results in the formation of a sample-spanning, self-supporting physical gel that exhibits an elastic modulus ( G') five orders of magnitude higher than the water-free system. A structure formation mechanism consisting of hydration layer formation followed by interparticle water bridging has been proposed to explain the observed behavior. Recovery of the original viscoelastic fluid is demonstrated by adding molecular sieves (e.g., zeolites) to the fully flocculated system. The recovery can likely be attributed to the adsorption of water by the sieves and the corresponding breakup of water bridges between the ATH particles. On the basis of the proposed mechanism, a variety of other polar and nonpolar solvents have been found to induce physical gelation in ATH/PDMS dispersions with gel modulus being related to the Hildebrand solubility parameter mismatch between the solvent and PDMS fluid.

Mineral trapping of a CO2/H2S mixture by hematite under initially dry hydrothermal conditions

For the experimental simulation of geochemical processes occurring in the vicinity of an injection well for CO2 with H2S impurities, the reaction of hematite with a CO2/H2S acid gas mixture in an initially water-free system was investigated. At the reaction conditions (120°C, 12MPa), a reductive dissolution of hematite and the successive precipitation of iron sulfide minerals pyrrhotite, marcasite and pyrite together with siderite were observed within days. Precipitation of secondary minerals presumably occurred either in the supercritical CO2 phase or, more likely, in an aqueous phase generated during the reaction progress due to the high initial H2S portion in CO2. The overall process can be described byFe2O3+2H2S+CO2→FeS2+FeCO3+2H2O.The observed process is relevant for the geologic co-storage of CO2 with H2S in sandstone formations with a substantial fraction of hematite (e.g. red-beds). There, mineral trapping of CO2 will be significantly promoted by reaction of co-injected H2S or SO2 with hematite – even in the dried-out zone near the injection well. This process can significantly impact the porosity of the storage rock due to an initial dissolution of hematite and subsequent deposition of secondary minerals with larger total volume. Hence, a plugging of pore throats appears to be feasible even in the desiccated zone in the vicinity of a CO2 or acid gas injection well.

An investigation on environmentally friendly biodiesel-based invert emulsion drilling fluid

As one blend of monoalkyl esters of fatty acids, biodiesel has a potential to serve as the external phase of drilling fluid due to its abundant sources, great safety, low toxicity, and excellent biodegradability. There are some investigations on designing of biodiesel-based drilling fluids, but most of them are about water-free system instead of emulsion system which is the most commonly used. In this paper, a biodiesel-based invert emulsion drilling fluid (BBDF) was prepared and its properties were evaluated. The results revealed that this drilling fluid has high electrical stability, acceptable rheological parameters, and satisfactory filtration property. After hot-rolling at 120 °C for 16 h, these properties are still able to meet the operational requirements for drilling engineering. BBDF can tolerate 10 % sea water, or 15 % drilling solid. Due to its excellent lubricity, low toxicity, and great biodegradability, it is suitable to be used in extended reach drilling, directional drilling, or horizontal drilling. The biodiesel and emulsifier in this drilling fluid system are both produced from waste cooking oil. This may promote the waste recycled and utilized in a more effective and integral way. Some economic analysis and discussion were also made, indicating the cost feasibility of BBDF. Evidently, biodiesel-based drilling fluid has a considerable value for further investigation.

A Novel Softening Finishing of Cotton Fabrics by Silicone Softener/D5 Dispersion System

Due to the cumbersome emulsification process and water pollution, the traditional softening finishing by silicone softener in aqueous bath can not fulfill the acquirements of energy saving and emission reduction during the production of cotton fabrics. For this reason, a novel water-free system containing silicone softener and decamethyl cyclopentasiloxane (D5) is introduced to the softening finishing. Compared to the traditional softening finishing in aqueous bath, the novel softening finishing system can obtain almost the same softening finishing effect and the adsorption rate of silicone softener is about 75%. In the meanwhile, the finishing can be processed at a lower temperature. Simultaneously the water pollution can be prevented due to the fact that D5 can be recycled after finishing. The finishing conditions including mangle expression, bath ratio of D5, finishing temperature and finishing time were optimized by evaluating the curve area value and softness score of PhabrOmeter3 fabric evaluation system. The result indicated that simple preparation and eco-friendly finishing could be realized by applying the novel D5 softening finishing system. From the investigation, the novel system with silicone softner/D5 dispersion can be a promising candidate for the softening finishing in future, as it is environmental friendly.

Gallic acid‐based alkyl esters synthesis in a water‐free system by celite‐bound lipase of Bacillus licheniformisSCD11501

Gallic acid (3, 4, 5- trihydroxybenzoic acid) is an important antioxidant, anti-inflammatory, and radical scavenging agent. In the present study, a purified thermo-tolerant extra-cellular lipase of Bacillus licheniformis SCD11501 was successfully immobilized by adsorption on Celite 545 gel matrix followed by treatment with a cross-linking agent, glutaraldehyde. The celite-bound lipase treated with glutaraldehyde showed 94.8% binding/retention of enzyme activity (36 U/g; specific activity 16.8 U/g matrix; relative increase in enzyme activity 64.7%) while untreated matrix resulted in 88.1% binding/retention (28.0 U/g matrix; specific activity 8.5 U/g matrix) of lipase. The celite-bound lipase was successfully used to synthesis methyl gallate (58.2%), ethyl gallate (66.9%), n-propyl gallate (72.1%), and n-butyl gallate (63.8%) at 55(o) C in 10 h under shaking (150 g) in a water-free system by sequentially optimizing various reaction parameters. The low conversion of more polar alcohols such as methanol and ethanol into their respective gallate esters might be due to the ability of these alcohols to severely remove water from the protein hydration shell, leading to enzyme inactivation. Molecular sieves added to the reaction mixture resulted in enhanced yield of the alkyl ester(s). The characterization of synthesised esters was done through fourier transform infrared (FTIR) spectroscopy and (1) H NMR spectrum analysis.

A cleaner approach for biolubricant production using biodiesel as a starting material

Abstract By this study we aimed to develop a green and cleaner alternative to the existing oil-derived lubricant production by providing the market biolubricant synthesis catalyzed by enzymes. Moreover, the use of biodiesel to develop a higher added-value product is a very attractive solution for biodiesel production manufacturers in extending their production supply and the potential sales markets, especially in the East Europe region. The synthesis of 2-ethyl-1-hexyl oleate (biolubricant) was studied using commercially available immobilized lipase Lipozyme TL IM, biodiesel as a source of fatty acids and relatively cheap 2-ethyl-1-hexanol. The transesterification reaction was performed in solvent-free and water-free system. 2-Ethyl-1-hexyl oleate was successfully synthesized in 50 L scale with 100 % conversion in 10 h of reaction time at 60 °C temperature. The physico-chemical properties of 2-ethyl-1-hexyl oleate were estimated.

Functionalisation of the nido-dicarbaborate anion nido-7,8[formula omitted] by hydride abstraction

Substitution at the dicarbaborate anion nido-7,8-C2B9H12− (1) with precise hydride abstraction leads to symmetric products 10-R-nido-7,8-C2B9H11, e.g., 10-[cyclo-(CH2)4O]-nido-7,8-C2B9H11 (2) and 10-[cyclo-(CH2)4S]-nido-7,8-C2B9H11 (3). However, this approach has been limited to acetaldehyde as hydride acceptor in an acidified, aqueous two-phase system. In expanding the concept of hydride abstraction, we have found that acetone, activated by AlCl3, is capable of accepting hydride with substitution of the symmetric B10 position in the presence of suitable donor molecules (Lewis bases). Thus, by employing a one-phase water-free system, 2 and 3 as well as moisture-sensitive 10-CH3CN-nido-7,8-C2B9H11 (4) were obtained in good to high yield. Reactions with 1 in neat acetone gave 10-HO-nido-7,8-C2B9H11− (7). An alternative reagent for hydride abstraction in 1 is tritylium tetrafluoroborate (Ph3CBF4), which gave 10-Ph2S-nido-7,8-C2B9H11 (11) in the presence of Ph2S. The Ph2S moiety in 11 could easily be replaced by pyridine and triethylamine, giving 10-C5H5N-nido-7,8-C2B9H11 (12) and 10-Et3N-nido-7,8-C2B9H11 (13). Additionally, reactions of 1 with CF3SO3H in the presence of CH3CN or CH3SCN gave 9-CH3C(NH2)-nido-7,8-C2B9H11 (5) and 9-CH3SC(NH2)-nido-7,8-C2B9H11 (6) by electrophilic substitution.

Myriophyllum aquaticum versus Lemna minor: Sensitivity and recovery potential after exposure to atrazine

The relative sensitivity and recovery potential of two aquatic macrophyte species, Lemna minor and Myriophyllum aquaticum, exposed to atrazine (concentration ranges 80-1,280 µg/L and 40-640 µg/L, respectively) were evaluated using slightly adapted standard protocol for Lemna spp.: relative growth rates (RGR) and yield of both plants were measured in 3-d-long intervals during the exposure and recovery phase. Myriophyllum aquaticum was also exposed to atrazine-spiked sediment (0.1-3.7 µg/g) in a water-free system. The results of M. aquaticum sediment contact tests showed that root- and shoot-based growth parameters are equally sensitive endpoints. In the water (sediment-free) test system, L. minor recovered after short (3 d) and longer exposure (7 d) to all atrazine concentrations after only a 5- to 6-d-long recovery phase. The recovery of M. aquaticum after short exposure was slower and less efficient: after 12 d of recovery phase the final biomass of plants exposed to 380 and 640 µg/L was below the initial values. The last interval RGR provides a good indication of plant recovery potential regardless of species growth strategy. If compared to L. minor, the difference in growth rate, sensitivity, lag phase, recovery potential from water-column substances, and also suitability for studies investigating the effect of sediment-bound pollutants advocates the use of M. aquaticum as an additional macrophyte species in risk assessment.

Continuous Production of Soybean Biodiesel in Supercritical Ethanol−Water Mixtures

The reaction efficiency of soybean oil transesterification in supercritical ethanol in a continuous catalyst-free process was investigated under different water concentrations. Experiments were performed at 350 °C and 20 MPa, with an oil/ethanol ratio of 1:40. A fatty acid ethyl ester content of 77.5% was obtained at a flow rate of 1.5 mL/min in a water-free system, while the maximum concentration of ethyl esters reached for a water content of 10 wt % was 68.1% at a flow rate of 1.0 mL/min. Decomposition and trans-isomerization of unsaturated fatty acids were significantly affected by the flow rate, with a pronounced reduction in the ratio of C18:2/C16:0 in the final product compared to the starting oil.

Effect of Water on Foaming Properties of Diglycerol Fatty Acid Ester−Oil Systems

We have studied the effect of added water on the nonaqueous foaming properties of diglycerol fatty acid ester nonionic surfactant systems. Diglycerol monomyristate (designated as DGM) could not foam in nonpolar oils squalane and hexadecane at normal room temperature. Nevertheless, addition of a small amount of water induces a dramatic change in foaming properties. Both the foamability and foam stability increases with the amount of added water within the studied concentration range. Phase behavior study showed that in the dilute regions there is dispersion of solid surfactant in the aforementioned oils in the DGM systems. The particle size of the dispersed solid phase was found to be several tens of microns in the water free system, and hence it tends to coagulate and precipitate. In the case of shorter alkyl chain length, diglycerol monolaurate (DGL) surfactant-oil systems, dispersion of lamellar liquid crystal (Lalpha) is observed at room temperature, and the poor foaming properties were attributed to the large particle size of the liquid crystal. In both the DGL and DGM-oil systems, we observed a tendency of the particle size to decrease with the increasing concentration of added water. At higher temperature, the solid surfactant transforms to lamellar liquid crystal phase, and foaming is improved in the DGM/squalane system. Foams are stable for several minutes. Judging from the foaming test and particle size distribution data it can be concluded that the poor foaming in the diglycerol fatty acid esters-oil systems may possibly be due to bigger particle size, which causes precipitation. Addition of water results in the dispersion of smaller particles and improves the foaming behavior.

An experimental study of cassiterite solubility in HCl-bearing water vapour at temperatures up to 350 °C. Implications for tin ore formation

The solubility of cassiterite was investigated experimentally in liquid-undersaturated HCl-bearing water vapour at temperatures of 300 to 350 °C and pressures up to 180 bar. Concentrations of tin varied between 0.1 and 32 ppb, depending on experimental conditions, and reached a maximum at 320 °C. These concentrations are at least four orders of magnitude higher than those reported for the water-free system. Positive correlation of the concentrations of tin with f H 2O and f HCl indicate that cassiterite solubility is enhanced by solute–solvent interaction, and that this involves the formation of hydrated gaseous species of tin chloride having a tin–chlorine ratio of 1:2, and statistical hydration numbers of 2.9, 2.7, and 2.5 at 300, 320, and 350 °C, respectively. We therefore propose that the solubility of cassiterite in HCl-bearing water vapour is explained by the reaction: SnO 2 cassiterite + 2 · HCl gas + n · H 2 O vapour = SnOCl 2 · ( H 2 O ) n + 1 vapour Calculations based on this reaction and data for the solubility of tin in aqueous liquids indicate that, under all conditions, tin partitions preferentially into the latter phase. However, in high salinity, two-phase aqueous systems, where vapour pressures can be considerably higher than those in our experiments and chlorinity is not controlled by f HCl, but by NaCl content, tin solubility in the vapour phase may be appreciable.

Molecular dynamics simulation of the structure of PEO based solid polymer electrolytes

A water-free solid polymer electrolyte containing poly(ethyle oxide) (PEO) and poly(ethyle oxide) with sulfonic acid dianion end groups (PEO sulfonic acid dianion) is constructed using periodic boundary conditions by atomistic molecular modelling. The vibrational frequencies are calculated and found to be in agreement with the measured spectra. The structure of the PEO sulfonic acid dianion is studied by calculating the dihedral angle distributions and the intramolecular pair correlation functions between the carbon atoms and the ether oxygen atoms. The dimensional analysis is made. Results concerning the PEO sulfonic acid dianion in the water-free system are compared to the results obtained in the water containing systems and in vacuum. The structure of the PEO sulfonic acid dianion in water-free system is found to be rather similar to its structure in water and PEO containing system but different from its structure in vacuum.

New technique to controlin situ oxygen fugacity in water-free high-pressure system

Through inserting a solid oxygen-specific electrolyte (YSZ) inside and exerting an electrical power of direct current outside between the sample and oxygen reservoir (an solid oxygen buffer), oxygen was driven by the power from the cathodic electrode area into the positive electrode area at high temperature and high pressure. In this way, the oxygen fugacity in the sample wasin situ controlled independently of temperature and pressure. By using Cu-O system as an example, this technique was proved to be successful.

Water-free solvent system for droplet counter-current chromatography and its suitability for the separation of non-polar substances

Water-free solvent system for droplet counter-current chromatography and its suitability for the separation of non-polar substances

Leitfähigkeit des flüssigen Systems Ameisensäure + Essigsäure / Conductivity of the Liquid System Formic Acid + Acetic Acid

Results of measurements of the electric conductivity and of the molar volume for the water-free liquid system formic acid-f-acetic acid are presented. They cover the whole composition range at temperatures between 0 °C and 50 °C. The equivalent conductivity and the activation energy are also given.