Glycol Aqueous Solution Research Articles

Thermal contraction of aqueous glycerol and ethylene glycol solutions for optimized protein-crystal cryoprotection.

The thermal contraction of aqueous cryoprotectant solutions on cooling to cryogenic temperatures is of practical importance in protein cryocrystallography and in biological cryopreservation. In the former case, differential contraction on cooling of protein molecules and their lattice relative to that of the internal and surrounding solvent may lead to crystal damage and the degradation of crystal diffraction properties. Here, the amorphous phase densities of aqueous solutions of glycerol and ethylene glycol at T = 77 K have been determined. Densities with accuracies of <0.5% to concentrations as low as 30%(w/v) were determined by rapidly cooling drops with volumes as small as 70 pl, assessing their optical clarity and measuring their buoyancy in liquid nitrogen-argon solutions. The use of these densities in contraction matching of internal solvent to the available solvent spaces is complicated by several factors, most notably the exclusion of cryoprotectants from protein hydration shells and the expected deviation of the contraction behavior of hydration water from bulk water. The present methods and results will assist in developing rational approaches to cryoprotection and an understanding of solvent behavior in protein crystals.

Boiling heat transfer characteristics of ethylene glycol and water mixture based ZnO nanofluids in a cylindrical vessel

Pool boiling heat transfer characteristics including boiling heat transfer coefficient (HTC) and critical heat flux (CHF) of ethylene glycol (EG) and deionized water (DW) mixtures based ZnO nanofluids are experimentally investigated in a cylindrical vessel under atmospheric pressure. As the heat flux goes on, the boiling HTC of nanofluids increases in an obvious way for the natural convective region while gradually increases in the nucleate boiling region. In addition, a significant enhancement of CHF between nanofluids and their respective base fluids is observed. The HTC and CHF are enhanced due to the surface wettability reduction and nanoparticle coating on heater surface. Results also show that only the nanofluids with ZnO mass fraction less than ∼7.25% could enhance the boiling heat transfer capability of vol.%=85% EG aqueous solution.

Effect of major degradation products of ethylene glycol aqueous solutions on steel corrosion

The effect of major degradation acid products of ethylene glycol (EG) aqueous solutions, namely glycolic, formic, acetic, and oxalic acids, on the corrosion behavior of low carbon steel was investigated under stirring conditions at 80°C by means of well-established techniques for electrochemical, physico-chemical, and surface analyses. The electrochemical behavior of steel under polarization conditions is dominated by active dissolution of iron with Fe2+ production leading to oxide products and H+ reduction as the cathodic counterpart. No correlation was found between the corrosion current density estimated by Tafel extrapolation method and that determined by the rate of production of Fe2+ under free corrosion conditions. The latter experiments revealed that the nature and the relative proportion of carboxylic acids influence the corrosion behavior of steel. The rate of production of soluble corrosion products increases with the stability and complexation ability of the organic anion towards Fe3+, being more significant in the case of glycolic acid in excess with high chelation propensity. Conversely, formation of Fe2+ and Fe3+ oxalates on iron surface is promoted in the presence of oxalic acid due to a catalytic action on magnetite dissolution. The extent of above processes is compromised if hydrogen bonding interactions between different carboxylic acids are privileged.

Effect of Pb2+ and Cu2+ as a codopant on the structure, morphology and conductivity of nanostructured polyaniline

ABSTRACTPolyaniline (PANI) has been successively synthesized in aqueous diethylene glycol solution medium by chemical oxidative polymerization of aniline using ammonium peroxidisulfate [(NH4)2S2O8] as an oxidant in an aqueous solution of 0.5 M acetic acid (CH3COOH) as a dopant. Polyaniline–lead (PANI–Pb) and polyaniline–copper (PANI–Cu) nanocomposites have been chemically prepared for the first time by oxidative polymerization of aniline in aqueous diethylene glycol/acetic acidic medium. The synthesized PANI and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR). Conductivity measurements of the polymer and nanocomposites were performed using the four-probe technique. Morphology changes of the composites were investigated by scanning electron microscopy (SEM). PANI nanotubes were formed without added codopant, but when Pb(CH3COO)2 or Cu(CH3COO)2 was added as a codopant, the morphology of PANI obviously changed. The PANI–Cu and PANI–Pb nanocomposites exhibit higher conductivity than the PANI homopolymer, but the conductivity of the composites slightly decreased on increasing the metal concentrations.

Synthesis of mono‐dispersed ceria hollow nanospheres by a hydrothermal method

Mono-dispersed ceria (CeO2) hollow nanospheres about 400 nm have been prepared via a facile one-step hydrothermal method, wherein cerium nitrate hexahydrate (Ce(NO3)3·6H2O) was used as cerium sources with the assistance of polyvinylpyrrolidone (PVP) in the ethylene glycol aqueous solution. X-ray diffraction, X-ray photoelectron spectra, scanning electron microscope, transmission electron microscope, nitrogen adsorption–desorption and Fourier transform infrared results indicate that PVP can improve the dispersion and control the morphology and sizes of CeO2 hollow nanospheres as a surfactant, and the internal diameter of CeO2 hollow nanosphere gradually increases with reaction time. Based on the time-dependent experiment, the formation mechanism was proposed and discussed. These CeO2 hollow nanospheres show an excellent adsorption rate of heavy metal ions for Cr(VI) and the adsorption rate is about 70%. The CeO2 hollow nanospheres also had exhibited superior performance in the degradation of methyl orange dye.

Simplified component model of heating and dry-cooling coils: Influence of altitude and of glycol concentration in the heat transfer fluid on the error prediction of the heat transfer rate

An empirical model for predicting the thermal capacity of a coil operating in dry mode is investigated. It is based on the well-known ε-NTU method. Thermal resistances are estimated by empirical correlations calibrated with manufacturer data by using two operating cases. Large number of operating cases by ranging the inlet states, the flow rates of both fluids, the altitude and the propylene-glycol concentration is considered in tests. The validity of several approaches of the empirical model is investigated for heating and dry-cooling operating cases. When considering pure water as heat transfer fluid, acceptable results were achieved without any correction of properties.Similar tests were conducted considering propylene-glycol aqueous solution as heat transfer fluid. The error indicators are significantly reduced when the variation of the fluid properties is taken into account. According to the large number of tests conducted, the approach considering the correction of properties of both fluids is a promising procedure for the simulation of the coil, operating either as a heater or as a dry cooler, in TRNSYS, EnergyPlus or other dynamic simulation tools.The validity of the empirical component model is also investigated by using available experimental data published in the literature using aqueous solution of ethylene glycol as heat transfer fluid. Although the number of experiments used is not large and the accuracy of some measured cases is not as good as desirable, the tested approaches with and without correction of properties provide acceptable results.

Role of nanoparticles on boiling heat transfer performance of ethylene glycol aqueous solution based graphene nanosheets nanofluid

As the ethylene glycol aqueous solution (EG/DW) with a volume fraction of 60:40% (the ratio of ethylene glycol (EG) and deionized water (DW)) was widely used as an antifreeze solution, pool boiling heat transfer (BHT) characteristics including boiling heat transfer coefficient (HTC) and critical heat flux (CHF) of EG/DW based graphene nanosheets (GNs) nanofluids are experimentally investigated under atmospheric pressure. The influence of heat flux and nanoparticles mass fraction on the boiling heat transfer has been measured and discussed. Boiling curves were obtained for the nanofluids compared with the baseline case of EG/DW. It was shown that for low concentration (i.e., mass fraction up to 0.02%) GNs-EG/DW nanofluids, the boiling performance of the EG/DW had been obviously enhanced by adding GNs nanoparticles, which was resulted from the enhancement of surface wettability caused by nanoparticles deposition. However, further loading GNs in EG/DW reduced the BHT capability of EG/DW, results from the GNs sedimentation and subsequent blockage of the nucleation sites. At the small concentration less than 0.02%, the CHF rapidly increases with increasing nanoparticle concentration. However, the CHF magnitude is almost the same for GNs-EG/DW nanofluids with concentration beyond the critical concentration.

New examples of chelating triketone-like ligands that promote formation of binuclear complexes

The present work is to investigate of binding properties of chelating triketone-like ligands, which are able to forming of binuclear complexes. The studied compounds are able to exist in cyclic or ‘close form’ (phenyl substituted or unsubstituted 2-hydroxy-2-(trifluoromethyl)chroman-4-ones) as well as in their associated ‘open form’ (phenyl substituted or unsubstituted 1,1,1-trifluoro-4-(2-hydroxyphenyl)butan-2,4-diones). In this paper there is good evidence for the compounds are being in solid in ‘close form’ (pre-ligands), whereas in basic solutions and when involved in metal ion coordination sphere they are being in ‘open form’ (ligands). Protolytic equilibria of the compounds in aqueous ethylene glycol solutions were studied. Schemes of acid-base equilibria of these compounds were proposed. Apparent ionization constants of compounds containing electron-donor and electron-acceptor substituents in the benzene ring were determined using spectrophotometric method. The binding properties of 1,1,1-trifluoro-4-(2-hydroxyphenyl)butan-2,4-dione towards Cu(II), Ni(II) and Co(II) were studied. The formation of 2:2 metal–ligand complexes was observed. X-ray analysis gives evidence the formation of complexes in which the ratio metal to ligand can be 1:2 and 2:2. Similar to β-triketones the studied ligands tends to formation of binuclear complexes with transition metal ions.

常温エチレングリコール水溶液における非イオン性界面活性剤の抵抗低減効果

The drag reduction (DR) of nonionic surfactant (oleyldimethylamine oxide, ODMAO) in ethylene glycol (EG) aqueous solutions was investigated at the solution temperature of 20 ºC. The pressure drop and flow rate were measured in the pipe flow system with the inner diameter of 5 mm. The concentration of ODMAO solutions was 1000, 2000, and 3000 ppm by weight. Regardless of the ODMAO concentration, the DR could not be obtained in EG aqueous solutions, in which the concentration of EG was fixed at 30 % by weight. It was revealed, however, that the addition of a small amount of salicylic acid noticeably improved the drag-reducing ability at the ODMAO concentration of 2000 and 3000 ppm even in the 30 % EG aqueous solution, as well as the pure aqueous solution, in which the higher DR was achieved at the lower concentration.

Infiltration of Nanoparticles into Porous Binder Jet Printed Parts

The densification of parts that are produced by binder jetting Additive Manufacturing (AM; a.k.a. “3D Printing”) is an essential step in making them mechanically useful. By increasing the packing factor of the powder bed by incorporating nanoparticles into the binder has potential to alleviate the amount of shrinkage needed for full densification of binder jet parts. We present preliminary data on the use of 316L Stainless Steel Nanoparticles (SSN) to densify 316L stainless steel binder jet parts. Aqueous solutions of Diethylene Glycol (DEG) or Ethylene Glycol (EG) were prepared at different DEG/water and EG/water molar ratios; pH of the solutions was adjusted by the use of 0.10 M sodium hydroxide. Nanoparticles were suspended in a resulted solution at a volume percentage of SSN/solution at 0.5%. The suspension was then sonicated for thirty minutes. One milliliter of the suspension was added stepwise to a sintered, printed disk with the dimensions: (d = 10 mm, h = 3 mm) in the presence of a small magnet. The 3D part was then sintered again. Moreover, the increase in the mass of the 3D part was used as indication of the amount of nanoparticles that diffused in the 3D part. This mass percent increasemore » was studied as a function of pH of the suspension and as function DEG/water molar ratio. Unlike EG, data show that change in pH affects the mass percent when the suspension was made with DEG. Finally, optical analysis of the discs’ cross sections revealed trends metallic densities similar to trends in the data for mass increase with changing pH and water molar ratio.« less

Metal Salt and Non-Electrolyte Separation by Means of Dialysis through the Composite Membranes

To separate salts of metals and non-electrolytes, the approach of dialysis through the composite membranes (CMs) is proposed. CM is a combination of cation and anion exchange areas. In the composite membrane, cations and anions are transferred through the respective exchange areas simultaneously without violation of macroscopic electro-neutrality. This provides a better transfer of salts than conventional ion exchange membranes (IEMs). The dialysis of the ethylene glycol aqueous salt solutions through the CMs was investigated. We have shown that the transport of salts through the composite membranes is more intensive (unlike IEM providing no transfer of salts from weakly mineralized aqueous solutions due to the Donnan exclusion) and the ethylene glycol transfer is not very significant, that is the basis of effective separation. The possibility to use of composite membranes for metal salt and other electrolyte separation is discussed.

Role of salt in the aqueous two-phase copolymerization of acrylamide and cationic monomers: from screening to anion-bridging

Mechanism for the anions effect on the aqueous two-phase copolymerization (ATPP) of acrylamide and cationic monomers in poly(ethylene glycol) (PEG) aqueous solution was proposed.

Effect of Dissolved Polymer on the Elasticity and Plasticity of a Lyotropic Lamellar Mesophase

SummaryUsing the Surface Force Apparatus (SFA) technique, direct force–distance measurements between mica surfaces immersed in a polymer‐doped lamellar phase are presented. In the aqueous layers separating the charged and undulating bilayers of sodium dodecyl sulfate (SDS)/octanol, water is replaced by a polyethylene glycol aqueous solution (PEG, Mw 20000 g/mol). As the mesophases align with the layers parallel to the solid mica surfaces the measurements yield structural information on the confined mesophases as well as bulk elastic properties. Keeping the membrane volume fraction constant the PEG dissolution results in a marked decrease in the elastic compressibility modulus, . This indicates a softening of the repulsive interactions between the lamellae mediated by polymer adsorption on the bilayers/aqueous solution interface. Insights into the behavior of the mesophases in confined geometries and thereby their stabilization mechanism are gained by noting a plastic contribution due to the presence of edge dislocations in the wedge‐like confinement geometry.

Highly sensitive microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) nanofibers

A microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] nanofibers has been developed. The flow sensor is able to linearly measure low flow rates ranging from 13 μl/h to 301 μl/h with a sensitivity of 0.36 mV per 1 μl/h, and the highest voltage difference of 120 mV at a flow rate of 451 μl/h. Moreover, the viscosity of the ethylene glycol aqueous solution ranging from 1 mPa·s to 16.1 mPa·s at 25 °C can be detected in dynamic flow with a stable output. These findings highlight the potential of piezoelectric P(VDF-TrFE) nanofibers in multiferroic applications.

Equilibrium Conditions of Xenon Hydrates in the Presence of Aqueous Solutions of Alcohols, Glycols, and Glycerol

Equilibrium conditions of xenon hydrates in the presence of aqueous solutions of alcohols, glycols, and glycerol were experimentally measured in a pressure range up to 1 MPa using an isochoric method. Adding the chemicals to water lowered the equilibrium temperature of xenon hydrate, indicating that the chemicals acts as the hydrate inhibitors. On a mass basis, the inhibiting effect on xenon hydrate formation decreased in the following order: methanol > ethanol > ethylene glycol > glycerol ≈ diethylene glycol > triethylene glycol. The order is the same as those for other hydrates of ethane, propane, and carbon dioxide.

Simultaneous Separation of Manganese, Cobalt, and Nickel by the Organic-Aqueous-Aqueous Three-Phase Solvent Extraction

This research outlines an organic-aqueous-aqueous three-phase solvent extraction method and proposes its use in a new metal separation process for the recycling of manganese (Mn), cobalt (Co), and nickel (Ni) from used lithium ion batteries (LIBs). The three-phase system was formed by mixing xylene organic solution, 50 pct polyethylene glycol (PEG) aqueous solution, and 1 mol L−1 sodium sulfate (Na2SO4) aqueous solution. The xylene organic solution contained 2-ethylhexylphosphonic acid (D2EHPA) as an extractant for Mn ion, and the Na2SO4 aqueous solution contained 1 mol L−1 potassium thiocyanate (KSCN) as an extractant for Co ion. Concentrations of the metal ions were varied by dissolving metal sulfates in the Na2SO4 aqueous solution. As a result of the experiments, Mn, Co, and Ni ions were distributed in the xylene organic phase, PEG-rich aqueous phase, and Na2SO4-rich aqueous phase, respectively. The separation was effective when the pH value was around 4. Numerical simulation was also conducted in order to predict the distribution of metal ions after the multi-stage counter-current extractions.

NaOH‐Aided Platinum Nanoparticle Size Regulation on Polybenzimidazole‐Wrapped Carbon Nanotubes for Use as Non‐Humidified Polymer Electrolyte Fuel Cell Catalyst

AbstractWe describe a method to control the size of platinum nanoparticles (Pt‐NPs) on poly[2,2′‐(2,6‐pyridine)‐5,5′‐bibenzimidazole] (PyPBI)‐wrapped pristine multi‐walled carbon nanotubes (MWNTs) without changing the loading amount by adding various concentrations of sodium hydroxide (NaOH) to the ethylene glycol aqueous solutions. The Pt‐NP sizes decreased from 3.8±0.4 to 1.7±0.1 nm with increasing NaOH concentrations. The mass activity of the oxygen reduction reaction was 224 mA mgPt−1 for the electrocatalyst with 3 nm Pt‐NPs, in which the power density reached 350 mW cm−2, which was 1.4 times higher than that of the electrocatalyst synthesized without NaOH (250 mW cm−2) at 120 °C and without any extra humidification. The electrocatalyst synthesized from a small amount of additional NaOH (0.5 mm) in the starting solution shows an enhanced performance and similar Pt stability. More importantly, the Pt‐NP size showed no effect on the Pt stability owing to the use of the PyPBI.

RAFT polymerization of acrylamide manipulated with trithiocarbonates in poly(ethylene glycol) solution

ABSTRACTThe reversible addition fragmentation chain transfer (RAFT) polymerization of acrylamide (AM) in aqueous two‐phase system was successfully carried out in polyethylene glycol (PEG) aqueous solution. Because of phase transition involved in the polymerization process, the ln([M]0/[M])‐time plots were indicated in two‐stages significantly. Both the initial homogeneous polymerization and the subsequent heterogeneous polymerization were under good control. The effects of various synthesis parameters such as polymerization temperature, concentration of CTA, and initiator on RAFT polymerization behaviors have been investigated. Furthermore, the evolution process of the droplet morphologies after separation was examined by transmission electron microscope. The results showed that the nuclei were formed throughout the whole heterogeneous polymerization and stable sphere particles with an average size of about 1 μm were produced finally. More importantly, it was also found that the viscosity played a significant role in the stabilization of the dispersion of polymer particles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43000.

Enhancement of Proton Ordering in the Hexagonal Ice in Contact with Polyethylene Glycol Crystal

Heat capacities and spontaneous enthalpy-relaxation effects for 20, 30, and 50 wt % polyethylene glycol (PEG) aqueous solutions subjected to a precooling treatment of quenching or annealing were measured precisely by adiabatic calorimetry. Ice and PEG crystals were produced as eutectoids at low temperatures with leaving a part of the glassy solution, and the eutectic temperature was determined to be 264 K. It was found that a small part of ice in the 20 wt % PEG aqueous solution which had been aged in a range of 200–260 K to enhance its crystalline fraction revealed a proton-ordering phase transition between ice Ih and XI. The phase transition is known to be observed in the ice doped with alkali hydroxides but not to be observed in bulk pure ice because of too long relaxation times for the proton rearrangement to occur; the hydroxide ions work as catalysts for accelerating the rearrangement. According to the present results, we proposed a new scheme for introducing Bjerrum’s defects of the L type at the ice interface in contact with a PEG crystal; the introduction enables the rearrangement to be accelerated and the proton ordering to be achieved.

Mid-infrared spectroscopic investigation of the perfect vitrification of poly(ethylene glycol) aqueous solutions.

Crystallization/recrystallization behaviors of poly(ethylene glycol) (PEG) aqueous solutions with water contents (WC's) of ∼36-51 wt % were investigated by temperature-variable mid-infrared spectroscopy. At a WC of 43.2 wt %, crystallization and recrystallization of water and PEG were not observed. At this specific WC value (WCPV), perfect vitrification occurred. Below and above the WCPV value, crystallization/recrystallization behaviors changed drastically. The crystallization temperature below WCPV (237 K) was ∼10 K greater than that above WCPV (226 K). Recrystallization above and below WCPV occurred in one (213 K) and two (198 and 210 K) steps, respectively. These findings resulted from the difference in the (re)crystallization behaviors of water molecules associated with PEG chains with helical and random-coil conformations. These two types of water molecules might have limiting concentrations for their (re)crystallization, indicating that perfect vitrification might have occurred when the concentrations of the two types of water molecules were less than the limiting concentrations of their (re)crystallization.