Low Glycol Research Articles

Examining Concentration-Reliant Zn Deposition/Stripping Behavior in Organic Alcohol/Sulfones-Modified Aqueous Electrolytes.

The practical application of Zn metal anodes in electronic devices is hindered by dendrite growth and parasitic reactions. Electrolyte optimization, particularly the introduction of organic co-solvents, is widely used to circumvent these challenges. Various organic solvents in a wide range of concentrations have been reported; however, their influences and corresponding working mechanisms at different concentrations are largely unexplored in the same organic species. Herein, economical, low-flammable ethylene glycol (EG) is used as a model co-solvent in aqueous electrolytes to examine the relationship between its concentration, anode-stabilizing effect, and mechanism. Two maximal values are observed for the lifetime of Zn/Zn symmetric batteries under EG concentrations from 0.05 vol% to 48 vol%. Zn metal anodes can stably run for over 1700h at a low EG content (0.25 vol%) and high EG content (40 vol%). Based on the complementary experimental and theoretical calculations, the enhancements in low- and high-content EG are ascribed to the specific surface adsorption for suppressed dendrite growth and the regulated solvation structure for inhibited side reactions, respectively. Intriguingly, a similar concentration-reliant bimodal phenomenon is observed in other low-flammable organic solvents (e.g., glycerol and dimethyl sulfoxide), thereby suggesting universality of this study and providing insight into electrolyte optimization.

Conventional and MW assisted PET glycolysis promoted by titanium based catalyst

Polyethylene terephthalate (PET) flakes from postconsumer bottles were depolymerized in the presence of ethylene glycol (EG) and titanium (IV) phosphate (TiP) as catalyst. Glycolysis was carried out both as conventional heated and under microwave (MW) irradiation. For the former method the reaction conditions were: molar ratio PET repeating unit to EG-1:2.77, without catalyst and with different amounts of TiP at 200 °C. The MW assisted process was performed under similar experimental conditions applying a power range 400–600 W. It was optimizated with respect to the catalyst concentration and yeild of bis(2-hydroxyethyl) terephthalate (BHET). The experiments showed that the optimal result was achieved in a MW reactor using 0.2 wt% TiP (based on PET weight) at 450 W for 45 min reaction time. The degradation product contained the monomer BHET (61.7%), dimers, trimers and low amounts oligomers and EG. The yield of BHET achieved was 87%. The glycolysis products were characterized by a combination of analytical techniques – chromatographic, spectroscopic and thermal methods. The comparison of both approaches showed the advantages of MW assisted degradation in view of efficiency and time saving.

Ethylene Glycol from Lignocellulosic Biomass: Impact of Lignin on Catalytic Hydrogenolysis

Short polyols, such as ethylene glycol (EG), are a popular target of catalytic hydrogenolysis of saccharides. However, studies on the use of untreated or pretreated lignocellulosic biomass as feedstock for polyol production are scarce. In this work, we have studied the impact of lignin on the catalytic hydrogenolysis of different biomass samples, targeting ethylene glycol. We first developed a hydrogenolysis protocol that is sensitive to lignin and feedstock impurities, such as ash and extractives. A matrix of biomass feedstocks with varying lignin content has been evaluated, by subjecting poplar, pine, and hay to solvent-based (water/ethanol/acetic acid) pretreatments and by preparing physical mixtures of pure microcrystalline cellulose with organosolv lignin. Lignin appeared to inhibit the activity of the hydrogenation catalyst, Raney-Ni, by hindering the formation of sugar alcohols in the presence as well as in the absence of the tungstate catalyst. However, lignin is not the root cause for the low EG yield typically obtained with untreated lignocellulose, as treated lignocellulose delivered high EG yields (30–35 wt %), irrespective of the lignin concentrations, which varied between 0 and 44 wt %, under identical demanding experimental conditions.

Synthesis and simulation of a distillation columns system for the propylene glycols mixtures separation

AbstractFour sequences were synthesized and simulated for the separation process of the propylene glycols mixtures: the direct, the indirect, and two proposed sequences. The simulation of the distillation columns system was performed with PRO/II program using a complete NRTL (nonrandom two‐liquids) thermodynamic model. Two mixtures were subject of the separation: one containing only propylene glycols, and another containing in addition a significant amount of water. The disadvantage of the direct and indirect sequences is that the columns are operated at high temperatures in the bottoms this fact leading to decomposition of propylene glycols. The proposed separation sequences aim to eliminate this disadvantage by taking into account the nearest effect of inert gas that water and propylene glycols with lower molar mass have on the separation mixture. The feed is introduced directly in the reboiler of the first column, where lower glycols and water act as an inert gas on the TePG vaporization. The proposed separation sequence of the propylene glycols and water mixture has a temperature in the reboiler with approximately 13 K lower beside the direct sequence.

Investigation on combustion and emission performance of a common rail diesel engine fueled with diesel-ethylene glycol dual fuel

EG (ethylene glycol) is a good oxygenated fuel for diesel due to structure and thermal conductivity. Based on dual fuel experiment on a modified diesel engine, combustion and emission characteristics are investigated at 1400 r/min with four low EG energy ratio (EGER) (named EG0, EG5, EG10 and EG15 respectively). Combustion results show that the peak cylinder pressure, the peak heat release rates (HRRs) and pressure rise rate increase when EG is used in fumigation mode. However, the maximum in-cylinder temperature changed little. Owing to the auto-ignition character, EG is ignited before diesel injection at 1.29 MPa BMEP, ignition delay is shorten from 0.97 MPa to 1.29 MPa BMEP, and postpone slightly from 0.48 MPa to 0.64 MPa BMEP. Combustion duration decreases with the increase of EGER. The brake thermal efficiency (BTE) is lower and the diesel equivalent brake specific fuel consumption (BSFC) is higher followed by the rise of EGER. For emissions, the NOX, THC, CO2 and soot emissions decrease followed by the rise of EGER at the same time, while CO emissions increase. EG reduce ultrafine particles (UFPs) and decrease the average diameter of UFPs particularly. In conclusion, EG is found to be a good choice for dual fuel diesel engine from 0.81 MPa to 1.29 MPa BMEP in the aspect of performance and emissions.

Rapid Breakdown Anodization for the Preparation of Titania Nanotubes in Halogen-Free Acids

TiO2 nanotubes were successfully prepared based on rapid breakdown anodization (RBA) without halogen ions. Typically, ethylene glycol (EG) containing hydrated oxalic acid, high temperature (>50°C), and high potential (>80 V) are required to produce RBA nanotubes without halogen ions. However, the restricted electrochemical conditions were changed significantly with each factor. The primary ions for the local breakdown of the anodic oxide to generate RBA nanotubes were attributed to the small amount of OH− generated from the dissociation of hydrated oxalic acid. Local breakdown of the oxide was enhanced using low viscosity EG, a high temperature, and high applied potential. However, if the temperature was greater than 100°C, a flat barrier-type oxide without RBA nanotubes was generated because of evaporation of H2O. In addition, too high potential led to a damaged oxide instead of the RBA nanotubes. All electrochemical conditions for the RBA nanotubes formations showed certain current density ranges during the anodization. A map for the formation of RBA nanotubes was suggested for selected electrochemical conditions.

In situ FTIR spectroscopic studies of ethylene glycol electrooxidation on Pd electrode in alkaline solution: The effects of concentration

We investigated the electrooxidation of ethylene glycol (EG) on polycrystalline Pd electrode in alkaline by in situ FTIR reflection spectroscopy, and focused on the effects of EG concentration (2mM–1M) on the reaction pathways. Voltammetric result shows the reaction order of EG is near 0.5. In situ FTIR results demonstrated that the reaction pathways and the product contribution strongly depend on the EG concentration. The oxidation degree of EG decreases with increasing EG concentration, and the main products gradually varies from CO32-, C2O42-, glyoxylate, to glycolate. Bridge-bonded CO (COB), generated from dissociative adsorption of EG, can be easily oxidized at low EG concentration. These facts were attributed to the competitive adsorption of EG itself and reaction intermediates with water, which inhibits the formation of oxygen species from water dissociation, a key oxygen donor for deep oxidation of EG. Even though, EG is still much better than ethanol as candidate fuel for alkaline direct alcohol fuel cells. The present study is of importance for understanding reaction mechanism of EG electrooxidation.

Evaluation of sodium dodecyl sulfate effect on electrocatalytic properties of poly (4-aminoacetanilide)/nickel modified carbon paste electrode as an efficient electrode toward oxidation of ethylene glycol

Poly (p-aminoacetanilide) (PPAA) was prepared by oxidation of PAA in acidic aqueous solution in the presence of sodium dodecyl sulfate (SDS) at the surface of carbon paste electrode (CPE). Then Ni (II) ions were incorporated to the polymer by immersion of the modified electrode in a 0.1 M Ni (II) ions solution. The electrochemical behavior of this modified electrode (Ni/SDS–PPAA/CPE) was investigated by using cyclic voltammetry and chronoamperometry techniques. The experimental results exhibited the stable redox behavior of the Ni (III)/Ni (II) couple immobilized at the polymeric electrode. This polymeric modified electrode has a very good activity toward the ethylene glycol (EG) electrooxidation in a 0.1 M NaOH solution. By comparison of the different responses to EG oxidation using electrodes Ni/SDS–PPAA/CPE, Ni/PPAA/CPE and Ni/CPE, we observed that Ni/SDS–PPAA/CPE is a more effective catalyst for the electrooxidation of ethylene glycol. The anodic peak current of EG increases with increasing ethylene glycol concentration up to 0.08 M. A diffusion-controlled process at low EG concentrations and a kinetic-controlled process at high EG concentrations are predominant. Finally, the catalytic rate constant ( k) for the ethylene glycol oxidation reaction was calculated 1.1 × 10 4 cm 3 mol −1 s −1 by using a chronoamperometric technique.

Influence of ethylene glycol pretreatment on effectiveness of atmospheric pressure plasma treatment of polyethylene fibers

For atmospheric pressure plasma treatments, the results of plasma treatments may be influenced by liquids adsorbed into the substrate. This paper studies the influence of ethylene glycol (EG) pretreatment on the effectiveness of atmospheric plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers with 0.31% and 0.42% weight gain after soaked in EG/water solution with concentration of 0.15 and 0.3 mol/l for 24 h, respectively. Scanning electron microscopy (SEM) shows that the surface of fibers pretreated with EG/water solution does not have observable difference from that of the control group. The X-ray photoelectron spectroscopy (XPS) results show that the oxygen concentration on the surface of EG-pretreated fibers is increased less than the plasma directly treated fibers. The interfacial shear strength (IFSS) of plasma directly treated fibers to epoxy is increased almost 3 times compared with the control group while that of EG-pretreated fibers to epoxy does not change except for the fibers pretreated with lower EG concentration and longer plasma treatment time. EG pretreatment reduces the water contact angle of UHMWPE fibers. In conclusion, EG pretreatment can hamper the effect of plasma treatment of UHMWPE fibers and therefore longer plasma treatment duration is required for fibers pretreated with EG.

Ethylene Glycol and Glycolic Acid in Postmortem Blood from Fatal Poisonings

Ethylene glycol (EG), a relatively infrequent cause of fatal intoxication, presents an analytical challenge for forensic confirmation in postmortem toxicology. We report EG and glycolic acid (GA) quantification in postmortem blood by gas chromatography coupled with ion trap mass spectrometry (GC-MS) analysis using a modification of a previously reported clinical method. The method is linear from 50 to 4000 mg/L with a limit of detection of 25 mg/L for both EG and GA. Interassay coefficient of variation (2.1-8.6%, 4.3-6.0%) and accuracy (96-101%, 92-105%) were determined for EG and GA, respectively. EG concentration by ion trap GC-MS correlated closely (R(2) = 0.995) with EG quantified by GC-flame-ionization detection. Analysis of blood from 20 autopsies with no evidence of EG exposure did not reveal detectable EG or GA. In 12 medical examiner cases with EG poisoning as cause of death, EG concentrations ranged widely from 58 to 7790 mg/L with a mean of 1830 mg/L, and the GA concentration averaged 1360 mg/L with a narrower range of 810-1770 mg/L. EG and GA levels correlate poorly (R(2) = 0.15) in postmortem blood with discordantly low EG concentrations in two cases. Birefringent oxylate crystals in renal tissue was a consistent finding. In conclusion, a sensitive and specific GC-MS method for detection and quantification of EG and GA has been validated and a study of fatal EG poisonings revealed forensic application of the method.

Preparation and shape control of multiple-arm magnetic particles

Multiple-arm magnetic CuFe 2O 4 particles have been synthesized via a simple one-step solution-phase route at the presence of ethylene glycol (EG) ligands, which plays a key role for the shape control of the particle. At low EG content, hexa-arm CuFe 2O 4 particles with average arm diameter 50 nm and length 400 nm were obtained. Furthermore, a possible mechanism of shape evaluation process of these magnetic particles is discussed.

Coordination chemistry of alkali and alkaline earth cations—I. Lower glycols as ligands

Employing conductometric studies in water and in isopropanol, dissociation constants ( K d ) of M(Pic) n salts (M = Li, Na, K, Cs, Mg, Ca, Sr or Ba; Pic = picrate) and overall formation constants ( K f ) of M(Pic) n complexes with glycol, diglycol, triglycol and tetraglycol have been determined. The K d sequences are Li > Na > K > Cs > Mg > Ca > Sr > Ba in water and Li ⪢ Mg > Na > Ca in isopropanol. In water only Na and K form complexes, viz. Na(Pic)-tetraglycol (1:1), K(Pic)-triglycol (1:2) and K(Pic)-tetraglycol (1:1) whereas in isopropanol Li and Ca form complexes, viz. Li(Pic)-diglycol (1:2), Li(Pic)-triglycol (1:2), Li(Pic)-tetraglycol (1:2), Ca(Pic) 2-diglycol (1:2) and Ca(Pic) 2-triglycol (1:2). K f values in isopropanol are in general an order of magnitude higher than those in water. The Ca(Pic) 2-tetraglycol systems in isopropanol afford a novel 1:1 crystalline complex.

Structural changes of ribosome by the action of ethylene glycol

The denaturation of ribosome and RNA by ethylene glycol (EG) has been studied in an attempt to further understand the conformation and stability of the ribosome. At high concentrations of EG, the ribosome, its subunits, and 16S RNA undergo drastic structural changes as shown by circular dichroism, ultraviolet absorption spectroscopy, and sedimentation velocity. Two separate conformational transitions were observed for the 30S subunit; one from 30 to 50% EG and another from 60 to 90% EG. This observation suggests the presence of two "domains" in the 30S subunit which differ in their stability. However, the 50S subunit undergoes a single sharp transition at 60 to 90% EG, consistent with the notion of a highly cooperative conformation. Association of the subunits stablizes part of the 30S subunit since the transition curve for the 70S ribosome does not exhibit significant change at the low EG concentration region as seen for the 30S subunit. Removal of proteins from the 30S subunit broadens the transition curve to lower EG concentrations and suggests the role of proteins in stabilizing the conformation of the 16S RNA.

ジー, トリーエチレングリコール-水-ブタノール系の相互溶解度

Mutual solubility of the diethylene glycol-water-butanol and triethylene glycol-water-butanol systems was measured at 20° and 40°. It was thereby found that the mutual solubility of these systems increased with increase of temperature, as in the case of monoethylene glycol-water-butanol system, though the solubility itself was somewhat greater than the latter. The difference in the solubilities between the two systems was very small. Comparison of the distribution curves of these three systems showed that glycol was distributed largely in the aqueous phase, especially at low temperatures and that lower glycols were distributed in a larger amount. The tie-line data of these systems at 20° and 40° were obtained from the measurement of their refractive indices and were found to be linear.