Role Of Ethylene Glycol Research Articles

Ligand Induced Morphology Change and Enhancement of Luminescence Emission in CaF2:Eu(III) Nanoparticles: The Role of Ethylene Glycol, Trisodium Citrate and EDTA in Tuning the Particle Size in Seeded-Growth Approach

Ligand Induced Morphology Change and Enhancement of Luminescence Emission in CaF2:Eu(III) Nanoparticles: The Role of Ethylene Glycol, Trisodium Citrate and EDTA in Tuning the Particle Size in Seeded-Growth Approach

Insight into the role of ethylene glycol on thermodynamics and nucleation kinetics of dimethyl terephthalate in mixed solvent system

Dissolution and nucleation are two essential processes for industrial crystallization. This paper investigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate (DMT) in solution. The DMT solubility in mixed solvent system (methanol-ethylene glycol) was determined by isothermal satiation approach, and the solubility was associated using seven models. The model fitting results were consistent with the experimental values. Based on the results, the metastable zone width (MSZW) of DMT was detected by the polythermal approach; the modified Sangwal's theory was used to investigate the nucleation behavior, which can provide a new way of thought for better analysis of the crystallization behavior. The results demonstrated that MSZW was associated with various elements, such as cooling rate, saturation temperature and mass fraction of ethylene glycol. The addition of ethylene glycol slowed down the nucleation rate as shown by the broadening of MSZW. We derive the solid-liquid interface energy, the nucleation driving force, the critical nucleation size and the critical Gibbs free energy according to the classical nucleation theory. It is demonstrated that the nucleation driving force and the solid-liquid interface energy are dependent and jointly influence the MSZW.

Unveiling the role of ethylene glycol for enhanced performance of PEDOT:PSS/Silicon hybrid solar cells

Recently, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and n-silicon (n-Si) based hybrid solar cells (HSCs) are given significant attentions owing to their cost-effective processing and promising photovoltaic performances. Pristine PEDOT:PSS, however, due to its limited electrical conductivity, cannot yield highly efficient HSCs. Doping of ethylene glycol (EG) in PEDOT:PSS boosts its electrical properties. However, role of EG on the formation, working mechanism of PEDOT:PSS/n-Si heterojunction and the performance of the HSCs are rarely explained. Herein, influence of EG on the optical, structural, electrical, and passivation properties of PEDOT:PSS along with polymer/n-Si heterojunction formation is investigated. HSCs with significantly enhanced power conversion efficiency (by ∼3.5 fold) is achieved for an optimal EG concentration (as compared to pristine PEDOT:PSS) on micro-engineered thin n-Si wafers even in the simplest device design. Optimal EG induces a strong inversion layer (p+-n junction) in n-Si at the polymer/Si interface enabling efficient separation and transportation of photo-carriers and hence enhanced solar cell performances. Formation of EG dependent strong electric field at polymer/n-Si interface is confirmed by the results of minority carrier lifetime, J-V characteristics, quantum efficiency, electrochemical impedance and C-V measurements of the HSCs. Role of EG in making an efficient PEDOT:PSS/n-Si solar cell is explained which may pave the way for further advancement of the cost-effective hybrid solar cell technology.

Effect of Ethylene Glycol on the Dissolution of Palladium with HCl Solution Containing Oxidizing Agents and Selective Precipitation of Pd(IV) Compound

There is growing interest in the recovery of pure palladium (Pd) compound from cemented Pd from spent electroplating solutions due to increasing demand for Pd, and there is considerable motivation to develop an efficient recovery process. In conventional methods of leaching Pd metal, HCl solutions containing oxidizing agents are employed. In this work, ethylene glycol (EG) replaced water as a diluent in the HCl solution containing oxidizing agents such as H2O2, NaClO and NaClO3. Leaching of the Pd metal and the subsequent precipitation of the Pd(IV) compound was investigated. Among the three kinds of oxidizing agent, NaClO3 showed the best Pd metal leaching efficiency from a metallic mixture of Pd and Zn from HCl in EG solution. The role of EG in enhancing the leaching and precipitation is discussed in light of its interaction with other components in the solutions. To precipitate the Pd(IV) compound with NH4Cl, it is important that the dissolved Pd ion exists as Pd(IV). Therefore, NaClO3 was again added to the leaching solution to verify the oxidation of Pd(II) to Pd(IV). Extra pure ammonium hexachloropalladate ((NH4)2PdCl6) was recovered by precipitation from the leaching solution of the cemented Pd under the optimum conditions. Compared to conventional HCl systems, the present process shows some advantages, by reducing both chemical dosage and energy consumption. The results confirm a process can be developed for the recovery of the Pd(IV) compound from spent electroplating solutions containing a small amount of Pd(II).

Electrochemical and leaching studies to better understand the role of ethylene glycol in the oxidative acid dissolution of chalcopyrite

It has been demonstrated that the combined use of organic compounds and acidic peroxide solutions greatly improves the dissolution kinetics of chalcopyrite. Among the additives employed, ethylene glycol (EG) is one of the most attractive for operating at moderate temperatures (20–50 °C). However, the role of EG in the leaching process is still not clearly understood, which limits optimization and industrial scale-up. For this reason, in this investigation, an electrochemical study was undertaken, using both a solid chalcopyrite (SE-Cp) electrode coupled to a rotating disk, as well as a chalcopyrite concentrate carbon paste electrode (CPE-CCp). Leaching experiments were also performed with EG and several other organic compounds, comparing the copper dissolved in each case. The results, in the mixed potential range of 0.55–0.75 V, showed that the presence of EG did not increase chalcopyrite oxidation. However, EG adsorption on the surface of the sulfide is sufficient to hinder hydrogen peroxide dismutation, the main cause of H2O2 decomposition in EG-free acidic solutions; at the same time, decreasing the interfacial tension favors chalcopyrite contact with the solution. Finally, the formation of similar products on the chalcopyrite surface, suggest that the organics additives do not alter the dissolution mechanism.

A study to understand the role of ethylene glycol in the oxidative acid dissolution of chalcopyrite

Recent investigations suggest that ethylene glycol (EG) performs two important functions in the oxidative dissolution of chalcopyrite with hydrogen peroxide: it prevents H2O2 dismutation on the chalcopyrite surface and, secondly, it hinders H2O2 decomposition due to the presence of dissolved copper and iron in the leach liquor. Of these two, retarding the H2O2 breakdown probably contributes most to the observed improvement in copper leaching; however, the nature of the role that EG plays in the solution is unclear. For that reason, a systematic study was undertaken, at different concentrations of sulfuric acid and EG, to reveal the role of EG in the leaching process. The results of this investigation show that EG hinders H2O2 degradation by decreasing the copper and iron activities in the solution through Cu (II)-EG and Fe (II, III)-EG complex formation. Likewise, the slowing effect strongly depends on the H2SO4 concentration because the Fenton reaction, which is responsible for the decomposition, increases its efficiency with lower acid concentrations (<0.1 M). Thus, successful leaching could be attained with concentrations above 0.7 M and 0.1 M of sulfuric acid and EG, respectively; otherwise, rapid H2O2 degradation and simultaneous EG mineralization (complete oxidation, in other words, oxidation to CO2 and H2O) are favored as a consequence of the reactions between H2O2 and the leached metals and the OH* radicals produced in the leach liquor, respectively. In view of these results, a brief discussion is presented on the implications of chalcopyrite leaching with H2O2, showing alternatives to increase its performance.

Effect of mechanical grinding on physical and chemical characteristics of circulating fluidized bed fly ash from coal gangue power plant

To characterize roles of mechanical grinding on the physical and chemical characteristics of circulating fluidized bed fly ash (CFB-FA), the differences between CFB-FA and ordinary fly ash (OFA) were revealed and the effects of mechanical grinding action on the physical and chemical characteristics of CFB-FA were studied from grinding kinetics, particle size distribution, bulk density, morphology, pore size distribution, amorphous substance content, anionic polymerization degree and hydration property and so on. The results indicate that there are some differences in chemical and mineral composition, particle morphology and self-hardening property between untreated CFB-FA and OFA. The particle size distribution of CFB-FA is optimized by mechanical grinding and the optimization role is best at 50min grinding time. Mechanical grinding action can also reduce the interconnected pores, average pore radius, total cumulative pore volume and the pores content in range of greater than 3nm radius of CFB-FA. Meanwhile, the amorphous substance dissolution amount of CFB-FA is increased and the polymerization degrees of [SiO4] and [AlO6] are reduced by mechanical grinding. All the 3d, 7d and 28d strengths of ground CFB-FA paste are improved significantly, and 3d and 28d activity index of the CFB-FA are also improved by more than 5% and 14%, respectively. Furthermore, organic grinding aids can further improve the mechanical grinding roles on CFB-FA and the role of ethylene glycol is the most excellent.

Systematical study of depositing nanoparticles and nanowires in mesoporous silica using supercritical carbon dioxide and co-solvents: morphology control, thermodynamics and kinetics of adsorption

AgNO3 was successfully deposited into mesoporous silica including SBA-15 and KIT-6 using supercritical carbon dioxide as the solvent, ethanol or a mixture of ethanol and ethylene glycol as the co-solvent, followed by calcination after depressurization. A large number of experiments were conducted to find out the most important parameters influencing the metal loading and the morphology of the nanostructure. The morphology was found to vary a lot according to the deposition time, which is interesting, i.e. small nanoparticles, short nanorods, continuous nanowires, and big nanoparticles appeared in succession as the deposition time increased. Besides, the co-solvent was also found to influence significantly the deposition results. The samples prepared using the mixture of ethanol and ethylene glycol as the co-solvent presented the morphology of nanowires, while those prepared using only ethanol as the co-solvent presented a mixed morphology of both nanoparticles and nanowires. The role of ethylene glycol was discussed and a mechanism model demonstrating the formation of Ag nanowires or nanoparticles was proposed. Finally, the adsorption of AgNO3 (adsorbate) from supercritical carbon dioxide and co-solvent (solvent) on the SBA-15 support (adsorbent) was investigated by both experimental and simulating methods. It was found that the adsorption isotherm was well fitted by the Langmuir model, and the kinetic investigation based on a mass differential equation showed that the adsorption reached equilibrium after 10 000 s (about 2.8 h) which was consistent with our experimental result (2.5 h).

Shape-Control Fabrication and Characterization of the Airplane-like FeO(OH) and Fe2O3 Nanostructures

Airplane-like FeO(OH) nanostructures have been first synthesized by an ethylene glycol (EG) assisted hydrothermal process and sequential annealing at 600 °C for 1 h. The as-prepared products were investigated by X-ray diffraction (XRD), UV−vis spectroscopy (UV), Raman spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). It is revealed that the single crystalline orthorhombic FeO(OH) nanostructures prepared by the EG-assisted hydrothermal process with airplane-like morphology can be easily transformed to single-crystalline hexagonal Fe2O3 nanostructures with airplane-like morphology. The critical role of EG in the hydrothermal synthesis of airplane-like nanostructures is discussed.

Optimization of parameters for the synthesis of nano-sized Co1−xZnxFe2O4, (0 ≤ x ≤ 0.8) by microwave refluxing

An optimization study of different parameters for the synthesis of well dispersed nanoparticles (5–30 nm) of the system Co1−xZnxFe2O4, (0 ≤ x ≤ 0.8) has been carried out using a novel microwave refluxing method. Ethylene glycol has been used as the medium which serves as the solvent as well as a complexing and capping agent. The parameters chosen were the zinc content (x), pH of the solution, reflux time and the metal∶ethylene glycol ratio. The influence of the above parameters is discussed in terms of the chemistry of the reactions and the role of ethylene glycol. The method appears much superior to other chemical/hydrothermal methods in terms of size distribution and dispersity of the nanoparticles.

Structural properties of gelatin—pectin gels. Part I: Effect of ethylene glycol

The role of ethylene glycol (EG) in the gelation mechanisms of acid pigskin gelatin and high methoxy pectin has been monitored and used as a baseline for the investigation of mixed gelatin—pectin gels in various mixed ethylene glycol—water solvents. The addition of EG did not alter the gelation (t gel ≈ 14°C) and melting (t mel ≈ 28°C) temperatures of an aqueous gelatin network, the strength of which, however, was first increased, and then reduced at concentrations of co-solute higher than 30%. The reduction in values of storage modulus (G) was attributed to a decrease in the proportion of polypeptide chains involved in the formation of junction zones. By contrast, increasing levels of ethylene glycol encouraged formation of pectin gels at high temperatures ( e.g. t gel was 63° Cat 80% EG) which largely retained their structure upon subsequent heating. The network strength increased rapidly and peaked at 60% co-solute followed by a subsequent reduction in storage moduli at conditions of low water activity (60–80% EG). On the basis of a model for gel formation involving a two-step process, it was proposed that ethylene glycol promotes the ordered structure of contiguous pectin chains (first stage) but ‘dissolves’ he hydrophobic clusterings of methyl groups (second stage). Differential scanning calorimetry demonstrated that thermodynamic incompatibility between the two polymers is the driving force behind the phase behaviour of mixed preparations. Based on the mechanical properties of single components, it was argued that increasing amounts of EG, within the 0–25% range, promote pectin's conformational ordering, which becomes more and more effective in excluding, concentrating up and strengthening the continuous gelatin phase. At higher levels of co-solute (from 30 to 70%), pectin can form a thermally stable network and during cooling it does so before gelatins gelation at lower temperatures. Light microscopy work strongly suggests that gelatin also forms a continuous network throughout the body of the sample. Therefore, the latter mixtures can be described as phase-separated, bicontinuous arrangements.

The Role of Ethylene Glycol and Polyethylene Glycol in the Freeze-Thaw Stability of Synthetic Latex

Abstract The freeze-thaw stability of synthetic latices obtained by the emulsion polymerisation of styrene, methyl methacrylate, methyl acrylate, vinyl acetate and acrylonitrile has been measured at the freeze-thaw cycles of −17.5°C and room temperature. It is found that the addition of ethyleneglycol and poly-ethyleneglycol into the latices increases the stability. The freezing point depression and the electrophoretic mobility of stabilized latices indicate the adsorption of stabilizing additives on the emulsion particles. Finally the adsorption of ethylene glycol and polyethylene glycol on the emulsion particles is determined directly. In consideration of these experimental results the freeze-thaw stability seems to be attained by the adsorption of additives on the emulsion particles.