Search results for "ELECTROLYTE"
showing 10 items of 746 documents
Solution properties of polyelectrolytes. I. Exclusion chromatography of sodium polystyrene sulphonate in salt-free water as eluent
1987
The effect of concentration of sodium polystyrene sulphonate on the elution volume in exclusion chromatography has been investigated using salt-free water as eluent. A non-linear increase in the elution volume has been observed with increasing injected sample concentration. Concentration-dependent calibrations have been obtained which approach the universal calibration for uncharged polymers (dextrans) as polyelectrolyte concentration increases. The separation mechanisms are interpreted in terms of electrostatic and hydrodynamic interactions. A semi-empirical model is proposed to predict concentration effects of linear polyions in exclusion chromatography and good agreement has been found b…
An electrochemical quartz crystal microbalance study of lithium insertion into thin films of tungsten trioxide II. Experimental results and compariso…
1995
Abstract Lithium insertion into amorphous thin films of tungsten trioxide (a-WO 3 ) prepared by thermal vacuum evaporation of WO 3 powder has been studied experimentally by chronoamperometry, cyclic voltammetry and ac impedance spectroscopy associated with electrochemical quartz crystal microbalance (EQCM). During cathodic polarization of the electrode and at short times two antagonistic processes occur. One is a non faradaic process and is associated with the expulsion of anions from the electrode surface under the effect of the electric field built in the electrolyte when a potential difference is imposed between the electrodes. The other one is the faradaic insertion of non-solvated lith…
Electro- and magneto-electrochemistry of zeolite Y- and MCM-41-associated bipyrylium ion
2005
Abstract The electrochemical response of bipyrylium bication [1,4-bis(3,5-diphenyl-4-pyrylium)phenylene] associated with Y and MCM-41 aluminosilicates (BTP@Y and BTP@MCM, respectively) is described using polymer-film electrodes immersed into Et 4 N + + MeCN and Bu 4 N + + MeCN electrolytes. BTP@MCM provides a solution-like response in all electrolytes consisting in two successive strongly comproportionation mediated one-electron reduction processes near to +0.05 and −0.12 V vs. Ag|AgCl. The response of BTP@Y in Bu 4 N + + MeCN is restricted to a unique reduction process near to −0.40 V, while in Et 4 N + + MeCN, it differs significantly: here, two reduction processes at −0.22 and −0.36 …
Isobaric Vapor–Liquid Equilibria of 1-Propanol + Water + Trifluoromethanesulfonate-Based Ionic Liquid Ternary Systems at 100 kPa
2011
Isobaric vapor–liquid equilibria (VLE) for the 1-propanol + 1-butyl-3-ethylimidazolium trifluoromethanesulfonate ([beim][triflate]), water + [beim][triflate], 1-propanol + 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyr][triflate]), and water + [bmpyr][triflate] binary systems, as well as the VLE for the 1-propanol + water + [beim][triflate] and 1-propanol + water + [bmpyr][triflate] ternary systems have been obtained at 100 kPa using a recirculating still. The salting-out effect on the 1-propanol produced by the [bmpyr][triflate] was stronger than that produced by the [beim][triflate], although for the IL concentrations used in this study the effect was not enough to break …
Quaternary ammonium polyiodides as ionic liquid/soft solid electrolytes in dye-sensitized solar cells
2007
Abstract Four new quaternary ammonium iodides, (Me 2 Pe 2 N)I, (Me 2 Hex 2 N)I, (Et 2 Pe 2 N)I and (Et 2 Hex 2 N)I, were synthesized and studied as electrolytes in dye-sensitized solar cells. All compounds were solids at room temperature. Influence of varying amounts of elemental iodine and the effect of tert -butylpyridine (TBP) on the performance of the cell was also studied. Addition of iodine lowered the melting points of the resulting polyiodides. From the ammonium iodides only (Me 2 Hex 2 N)I:I 2 (10:1) was liquid at the room temperature and the others were soft solids. Under illumination from a halogen lamp source at 10 mW cm −2 intensity, the highest power conversion efficiency of 2…
Trimesic acid on Cu in ethanol: Potential-dependent transition from 2-D adsorbate to 3-D metal-organic framework
2017
We report the potential-dependent interactions of trimesic acid with Cu surfaces in EtOH. CV experiments and electrochemical surface-enhanced Raman spectroscopy show the presence of an adsorbed trimesic acid layer on Cu at potentials lower than 0 V vs Cu. The BTC coverage increases as the potential increases, reaching a maximum at 0 V. Based on molecular dynamics simulations, we report adsorption geometries and possible structures of the organic adlayer. We find that, depending on the crystal facet, trimesic acid adsorbs either flat or with one or two of the carboxyl groups facing the metal surface. At higher coverages, a multi-layer forms that is composed mostly of flat-lying trimesic acid…
Anodic abatement of organic pollutants in water in micro reactors
2010
The electrochemical oxidation of oxalic acid (OA) was performed in a micro flow cell equipped with a boron doped diamond (BDD) anode. This preliminary study demonstrates that a flow cell with a micrometric distance between the cathode and the anode can be used to perform the electrochemical treatment of waters contaminated by organic pollutants in the absence of added supporting electrolytes with high abatements. The effect of the distance between the cathode and the anode, the flow rate and the current density on the abatement of oxalic acid and on the current efficiency was in particular studied.
Magnetic coiffure: Engineering of human hair surfaces with polyelectrolyte-stabilised magnetite nanoparticles
2022
Here we report a spontaneous electrostatic coating of human hair with aqueous Fe3O4 colloids capable to tailor magnetic properties to hair, orienting and even moving them under the influence of the external magnetic field. Magnetite particles were modified by cationic and anionic polyelectrolytes and then successfully deposited in dense arrays, starting from cuticle gaps and spreading further over a major hair surface. These biocompatible and biodegradable magnetic nanoparticles may serve as carriers for drug loading and delivery for topical pharmaceutical treatments. The deposition process was imaged in real-time using dark-field microscopy. The hair specimens were further studied using a …
Synthesis and some reactions of linear poly(iminohexamethylene)
1987
By complete reduction of polyamide-6, poly(iminohexamethylene) (PIH) was obtained. This new linear polyamine was characterized by i.r. and by n.m.r. spectroscopy as well as by titration. Differential scanning calorimetry measurements and X-ray diffraction found a high degree of crystallinity whose extent strongly depends upon the pre-treatment. The polyammonium salts that form with inorganic and organic acids show the typical polyelectrolyte effect in viscometry. PIH was alkylated with methyl iodide or acrylic acid and was acylated with N-BOC-l-α-amino acids or N-BOC-ω-amino-alkylenecarboxylic acids. The properties of these derivatives are described.
Donnan phenomena in membranes with charge due to ion adsorption. Effects of the interaction between adsorbed charged groups
1993
A physical model for the modified Donnan phenomenon associated with ion adsorption on localized membrane sites is presented. This model accounts for the dependence of the concentration of adsorbed ions on electrolyte concentration and pH as it is influenced by the electrostatic interaction between adsorbed ions. The equilibrium thermodynamic concepts employed are based on the Donnan formalism for the ion equilibria between membrane and solution, and the Bragg–Williams approximation for an adsorption isotherm that incorported interaction between adsorbed ions. Our results include the concentration of charged groups in the membrane, the pH of the membrane phase solution, and the Donnan potent…