Concentration Of Organic Additives Research Articles

Morphological influence of magnesium and organic additives on the precipitation of calcite

Calcium carbonate was precipitated from saturated solutions of calcium bicarbonate in the presence of magnesium and organic additives in order to investigate the effect of Mg-incorporation on calcite morphologies. A range of concentrations of Mg and organic additives were investigated, and the structure, composition and morphologies of the crystals were determined using X-ray diffraction and electron microscopy. The action of the organic additives in Mg-free solutions was highly specific, producing elongated single calcite crystals. A much wider range of calcite morphologies was observed in the presence of both Mg and organic additives, and a transition from single crystal to aggregates occurred on increasing the Mg concentration. The MgCO 3 content of the crystals increased with the solution Mg concentration, but showed little correlation with the organic additive concentration. Single crystals of magnesian calcite containing up to approximately 10% MgCO 3 were prepared, and typically exhibited rounded faces and edges. The polycrystalline aggregates had morphologies ranging from dumbbells to spheres and occluded up to about 22% MgCO 3. The experiments suggest that Mg 2+ ions act in combination with organic additives to affect calcite morphologies by mechanisms such as adsorption on specific crystal faces which inhibits growth, and by altering the calcite nucleation and growth processes.

Gel electrolytes from co-substituted oligoethyleneoxy/trifluoroethoxy linear polyphosphazenes

Four new co-substituted linear phosphazene polymers have been synthesized with controlled ratios of oligoethyleneoxy (MEEP-type) and trifluoroethoxy side groups. The polymers were synthesized as models for gel electrolyte systems with more dimensional stability than can be achieved by MEEP-type electrolytes alone. The conductivity is significantly influenced by the ratios of the two side groups and by the concentration of small-molecule organic additives. Insights are suggested into the mechanism of ionic conduction within polyphosphazene gels.

The effect of organic expander materials on the performance, life, surface area and crystal structure of negative electrodes in valve regulated cells

Valve regulated cells containing lignosulfonates and synthetic organic additives in their negative plates have been evaluated to determine their effect on capacity and cycle life. The negative active material was examined throughout cycle life to determine the effect of the additives on surface area and crystal morphology. Capacity tests were conducted over a range of current densities at ambient temperature and −18°C on cells containing the additives at various levels. All of the materials increased the capacity but considerable differences were observed in the capacity/dosage level responses. All of the organic materials increase the surface area of the active material, and the surface area increases with concentration. The additives produce a morphology composed of small equiaxial grains with high porosity and surface area. During cycling a progressive reduction in surface area takes place which eventually produces a dense structure with low porosity. The capacity and cycle life data show that each additive has a different optimum concentration in the plate. There are also indications that considerably higher concentrations of organic additives can be used in valve regulated batteries than is customarily used in flooded systems.

Ex Situ and in Situ Observations of the Surface Morphology of the (010) Face of Potassium Hydrogen Phthalate (KAP) Crystals

The surface morphology of the (010) face of potassium hydrogen phthalate (KAP) crystals grown from aqueous solution at low supersaturations (0.03 to 0.05) has been investigated using ex situ optical and electron microscopy in conjunction with a gold decoration technique. In situ atomic force microscopy (AFM) has also been used to examine the growth of dislocation-free hillocks. A variety of growth patterns was found: macroscopic hillocks, shallow hillocks, microscopic hillocks and numerous two-dimensional nuclei. The macroscopic hillocks and smaller polygonal hillocks are formed by groups of cooperating spirals or by single spirals. The density of observed shallow hillocks is higher than the dislocation density. The results reveal that, at low supersaturations, growth of the (010) face occurs by combined spiral and two-dimensional nucleation mechanisms. The influence of low concentrations of organic additives on the surface morphology of the (010) face of KAP has also been studied. The additives stimulate two-dimensional nucleation but they also cause an increase in the spread velocity of steps. The growth promoting effect of impurities is discussed in terms of the above data.

Capillary electrophoretic separation of polynuclear aromatic hydrocarbons using sodium cholate in mixed aqueous–organic buffers

A capillary electrophoretic method for the separation of a series of polynuclear aromatic hydrocarbons is described. Sodium cholate is used with a series of organic modifiers. Analysis times were between 26–80 min depending on sodium cholate concentration and on the type and concentration of organic additives used. Efficiencies in excess of 10 5 theoretical plates were observed.

Complexation between Amylodextrin Oligomers and Selected Pharmaceuticals Measured through Capillary Electrophoresis

The amylodextrin oligomers, tagged fluorescently at their reducing ends for laser fluorescence detection, were used as model solutes to investigate certain carbohydrate-drug interactions through capillary electrophoresis. The separation patterns of some oligomers were found to be altered significantly by the presence of selected pharmaceuticals used as buffer additives. The selectivity of complexation at a particular size of an oligomer could be judged from alterations in migration times and peak shapes. The formation of complex was influenced substantially by solutes' chemical environment (pH, ionic strength, and the nature and concentration of organic additives). The chemical nature of the guest molecules also played an important role in complexation. Using amylodextrins as chiral selectors, enantiomeric resolution of several pharmaceuticals was achieved electrophoretically. The conclusions drawn from electrophoretic data were found to be in close agreement with the results of a (13)C NMR study.

Determination of the quaternary ammonium compounds dequalinium and cetylpyridinium chlorides in candy-based lozenges by high-performance liquid chromatography.

The retention behavior of the quaternary ammonium compounds benzalkonium chloride, cetylpyridinium chloride and dequalinium chloride on a 100 x 4.6 mm id cyanopropyl stationary phase column is reported as a function of organic modifier and ionic hydrophobic mobile phase additive concentrations. Optimum liquid chromatographic mobile phases using different mobile phase additives are reported which are suitable for the determination of cetylpyridinium chloride and dequalinium chloride in a variety of candy-based lozenge formulations. The quantitative aspects of assays based on the separation of active ingredients and formulation excipients were established. The generality of application of the assay methods was evaluated by determining the quaternary ammonium content of different lozenges and comparing the values obtained with the stated dose.

Characterisation of alumina pastes for plastic moulding

A better understanding of the parameters controlling the interactions between particle surfaces and water solution would allow an improvement of highly concentrated ceramic paste behaviour for use in the extrusion process, as well as a dramatic decrease of the organic additive concentration needed to reach satisfactory plasticity. Therefore, the heat treatment step would also become easier and quicker. Alumina was selected as a model ceramic powder, and rheological and electrochemical measurements were performed using increasing dry matter content. It was shown that, at natural pH, an optimal range of dry matter content exists, corresponding to a minimum water content, which can be determined from plasticity data and from electro-chemical measurements.

Electrodeposition of low tin content zinc-tin alloys

ZnSn alloy coatings containing 10%–20% tin with good appearance were deposited from slightly acidic sulphate electrolytes. The effect of the concentration of tin sulphate and the cathodic current density on the composition and the structure of the alloy deposits was investigated. The partial deposition rates for Zn and Sn from electrolytes containing various brightener concentrations at a definite potential were determined. An increase in the concentration of organic additive from 1 to 5 ml 1 −1 leads to an abrupt decrease in zinc deposition rate, while the tin deposition rate decreases slowly. A further increase in brightener (organic additive) concentration does not affect particularly the deposition rate of either metal. The protective properties of ZnSn coatings were investigated by means of the Paatsch test. It is established that the corrosion resistance of ZnSn alloy deposits is better than the corrosion resistance of Zn and ZnCo (0.3%–1.3% Co) coatings.

Polyion interchange reactions of interpolyelectrolyte complexes in aqueous solutions and gels

AbstractCooperative coupling reaction between two opposite charged polyelectrolytes results in formation of polyelectrolyte complexes (IPEC). This reaction is very fast and diffusion controlled.Whether IPECs formed by linear polyions are soluble or limitary swellable in aqueous media is decided by their composition, namely, by a ratio of oppositely charged polyions as well as by a water phase composition (the nature and the concentration of a simple salt, pH, the presence and the concentration of organic additives etc.).The most important intrinsic property of IPECs is their ability to participate in interchange (exchange and substitution) reactions with competing polyions. The kinetics and the position of equilibria in these reactions are controlled by the low molecular salt concentration, the nature of small counterions, DP of interaction polyelectrolytes, as well as by their linear charge density.IPECs can be formed also by interacting linear and opposite charged networks. It is shown that linear polyelectrolytes dissolved in aqueous solution can penetrate unexpectedly fast into oppositely charged cross‐linked polyelectrolyte gels to form “snake‐in‐cage” composites representing IPECs of corresponding polyion segments. It is proved that the mechanism consists in “relay‐race” transfer of linear polyion segments from one segment of the polyelectrolyte network to the other via interpolyelectrolyte exchange reaction. The driving force for the fast transport of linear polyions into the gel is produced by coupling reaction between two polyelectrolytes proceeding on solution/gel interface.

Nickel fine particles' adsorptive-catalytic mechanism

The tribological properties of metal fine particles added to lubricants containing soluble organic additives were investigated. The adsorptive catalytic mechanism of nickel-containing fine particles was proposed and proved experimentally. The principal opportunity for lowering the soluble organic additive concentration in motor and transmission oils while simultaneously increasing their tribological characteristics was shown.

Self-affine growth of copper electrodeposits.

We have studied the static surface roughness of 50-\ensuremath{\mu}m-thick copper electrodeposits on length scales between 5 and ${10}^{4}$ nm using scanning tunneling and atomic force microscopy. The surface roughness depends strongly on the concentration of organic additives in the plating solution. Both the surface width and power spectra scale as a power of the system size. Self-affine surfaces became more fractal-like with decreased additives. The scaling exponent of the self-affine surface (1/2) is slightly larger than the simulation results for local growth models.

γ-Induced reduction of Eu(III) in aqueous solution

γ-radiation of Co60 has been applied to reduce Eu(III) to Eu(II) in aqueous solutions of the mixture of rare earths. The kinetics of the process has been investigated as a function of the absorbed radiation dose and organic additive concentration.

Underpotential Deposition of Copper on Gold and the Effects of Thiourea Studied by AC Impedance

This paper reports ac impedance and cyclic voltammetry studies of underpotential deposition (UPD) of Cu on Au in an electrolyte composed of and . A theoretical kinetic model was developed which fits the experimental impedance spectra over frequencies ranging from 0.001 to 20,000 Hz. Spectra are characterized by a two‐time constant process; two capacitive loops were observed in the Nyquist diagrams corresponding to two distinctive peaks in the Bode phase plot. The high frequency time constant is associated with the double‐layer capacitance, while the low frequency process is due to relaxation phenomena associated with the charge transfer involved in Cu2+ electrosorption. Thiourea is one of the most important organic additives for commercial plating baths. Therefore, the coadsorption of thiourea and UPD Cu on Au was also studied by ac impedance. Adsorbed thiourea was found to have a dramatic effect on the high frequency peak in the Bode phase plot. Measurements such as these are proposed as a means of determining organic additive concentrations in Cu plating and electroforming baths.

Effect of Dissolved Gases, Organic Additives and Field Configuration on Co-Field Motion in Insulating Oils

The effect of dissolved gases (02, air and N2) and a widerange of concentration of organic additives (quinoline,toluene and naphthalene) on the electrohydrodynamic headdue to co-field motion in transformer oil and liquid paraffinhas been measured fof both uniform and nonuniform fieldsusing direct voltages. The effect of gap length on thehead was also examined. The results indicate that all thedissolved gases investigated as well as toluene and napthalenereduced the developed head, whereas quinoline increased thehead. With a highly nonuniform field the effect of 02 andtoluene was found to be strongly dependent on the polarityof the point electrode.

Effect of the nature of organic solvents on their interaction with metal halides

The extraction of SbI3 by various organic solvents has been investigated as a function of H2SO4, KI and organic additive concentrations. At [Sb3+]: [I−]≈3, extraction increases in the order hexane → cyclohexane → kerosene → CCl4→CHCl3 → benzene → toluene → o-xylene → nitrobenzene.

ChemInform Abstract: THE EFFECT OF ORGANIC ADDITIVES ON THE MICELLE FORMATION OF DODECYLAMMONIUM HALIDES IN AQUEOUS SOLUTIONS

The critical micelle concentration (CMC) of dodecyl ammonium halides and the degree of dissociation of the micelle (α) of dodecylammonium chloride were determined as functions of the concentrations of the organic additives by measuring the conductivity and the emf of the following cell: calomel/1 M-KCl/sample solution/AgCl, Ag. The CMC was raised more in the presence of acetone and dioxane than in that of acetamide, formamide, urea, and methanol, and was diminished by adding alcohols (C2–C4). The effect of the alcohols on CMC decreased in the order of the diminished hydration of the counterion, acetone and dioxane were considered to affect the dodecylammonium iodide solution specifically. The dissociation of the micelle was enhanced in the presence of organic additives. Further, we estimated the solubilized amount of the additives from the degree of dissociation of the micelle and attempted to make quantitative estimation of the increment of CMC produced by organic additives.

Effect of Organic Additives, Gas Phase, Stress, and Temperature on the Gassing Characteristics of Insulating Liquids

This paper describes the effects of adding small concentrations of organic additives (anthraquinone, benzophenone, and diphenyl) to transformer oil on its gassing characteristics under different gas phases (H2, N2, O2, and air), different stresses and different temperatures. The results show that there exists an optimum concentration for each of the additives used. The optimum concentrations were found to be independent of the gas phase used. Also, for a given test liquid the results indicate the presence of an optimum stress for both gas-evolving and gas-absorbing oils. The results obtained are explained in terms of the free radical mechanism for gassing of oils under electrical stress.

Thermal Reactions of Hydrogen Atoms with Organic Compounds in Sulfuric Acid Glasses at Low Temperature

The formation (G values) and the thermal disappearance of hydrogen atoms in sulfuric acid glasses were measured as a function of time and concentration of organic additives (isopropanol, ethanol, thymidine, and 5-bromodeoxyuridine). Thermal hydrogen atoms react with isopropanol and ethanol at 77°K by abstraction and with thymidine by addition. With 5-bromodeoxyuridine as additive, the production of at least two different radical species was found at low temperature. One radical is due to the reaction with thermal hydrogen atoms, whereas the other radical could result from the reaction with the ( ${\rm SO}{}_{4}{}^{-}$ ) radical. A stepwise disappearance of the hydrogen atoms at different isopropanol concentration was observed.