Solubility Of Zinc Oxide Research Articles

Hydrolysis of Zinc Ion and Solubility of Zinc Oxide in High-Temperature Aqueous Systems

Hydrolysis constants of the zinc ion were measured at 25, 50, 75, 185, 200, and 225°C through the direct measurement of pH using pH sensors, especially of the yttria-stabilized zirconia membrane-type in the case of high temperatures over 185°C, and evaluation was done on the temperature dependence of the hydrolysis constants of the zinc ion. Solubilities of zinc oxide in pure oxygenated water were measured at 150, 200, and 250°C. Equilibrium constants of zinc oxide dissolution and the values of ΔGf0(Zn2+) at each temperature were estimated by thermodynamic analysis applying the estimated hydrolysis constants to the solubility data of ZnO.

Zinc oxoacidity properties in molten LiCl-KCl eutectic at 450� C

The solubility of zinc oxide was studied in molten LiCl-KCI eutectic at 450° C. For that purpose, a yttria-stabilized zirconia electrode was employed as a pO2− indicator. The most common calibration methods were reexamined, and it was shown that the ‘weighed additions’ method failed. The ZnO solubility product was determined.

An appraisal of the Caron Zinc Process when zinc ferrite is reduced to a magnetite containing product

As part of continuing research on a recently proposed process known as the Caron Zinc Process, a study has been made of the reduction of synthetic zinc ferrite to a magnetite containing product. The reduction has been carried out at 750°C using carbon monoxide as reductant. The Caron Zinc Process has been proposed with an aim of recovering zinc and other non-ferrous metals present in zinc ferrite containing materials. To realize this objective, the feed to the process would have to be subjected to a reduction roast and then an ammoniacal-ammonium carbonate leaching step. Assuming that pure zinc ferrite was to be used as feed and that the reduction step was to be carried out to a magnetite containing product, the results of the present work show that the recovery of zinc by the proposed process would not be more than 85 percent. Results of diffusion couple experiments have been used in combination with thermodynamic consideration of the reduction reaction and observed kinetics to arrive at the conclusion that the solubility of zinc oxide in magnetite would be the hinderance to higher zinc recovery.

Acidity and purification of the molten zinc chloride (33.4 mol%)-sodium chloride (66.6 mol%) mixture

The behavior of an yttria-stabilized zirconia electrode in the ZnCl22NaCl melt has been investigated between 450 and 500°C. The response of the electrode was nernstian and limited in oxobasic media by the solubility of zinc oxide. Although it is more acidic than LiClKCl eutectic melt, the chlorozincate can be purified towards oxide ions by gaseous reagents such as HCl and Cl2.

ChemInform Abstract: PROPERTIES OF ALTERNATE ELECTROLYTES FOR SECONDARY ZINC BATTERIES

AbstractGemischte, wäßrige Elektrolyte, in denen der KOH‐Anteil verringert wird und die damit verbundene niedrigere Leitfähigkeit partiell durch Zusatz von Salzen wie KF, K3PO4 oder K3BO3 kompensiert wird, werden hinsichtlich ZnO‐Löslichkeit, Ionenleitfähigkeit, Dichte und Verwendbarkeit von NiOOH als Elektrode untersucht.

Properties of Alternate Electrolytes for Secondary Zinc Batteries

Several mixed aqueous electrolytes have been characterized for zinc oxide solubility, ionic conductivity, density, and nickel hydroxide utilization. These electrolytes were made by reducing the usual potassium hydroxide concentration and by adding the salts such as potassium fluoride or potassium phosphate to partially compensate for the lower ionic conductivity. These mixed electrolytes may be useful in prolonging the cycle life of the zinc electrode in secondary batteries.

Leclanché Electrolyte Compositional Studies for Thin Film Batteries

The effect of zinc oxide dissolution and pH rise on the crystallization behavior of a series of Leclanché electrolytes has been determined with reference to their use in thin film batteries such as the ESB‐P70. An electrolyte (2725) consisting of 27% ammonium chloride and 25% zinc chloride was identified as exhibiting increased solubility of zinc oxide, increased resistance to both pH rise and harmful crystal formation when compared to the presently employed 2210 composition.

Ionic interaction in alkali metal hydroxide solutions — A raman spectral investigation

Raman spectral investigations made on concentrated solutions of potassium and sodium hydroxides in water, and on potassium hydroxide solution in methyl alcohol have confirmed the presence of clusters in these solutions. These clusters arise due to association between K + or Na + ion and OH − ion. The increase in temperature of the alkali metal hydroxide solution or the addition of hydroxide of zinc or aluminium to it leads to the dissociation of these clusters. This dissociation is responsible for the increase in the solubility of zinc oxide at room temperature when the solutions are prepared from the hot alkali metal hydroxide solutions. The dissociation further helps in the understanding the higher solubility of hydroxides of zinc and aluminium in concentrated alkali metal hydroxide solutions as compared to the corresponding oxides. The discrepancy in Raman studies on aluminate ions in concentrated akali metal hydroxide solutions and the nonlinear variation of refractive index of alkali metal hydroxide solution with concentration have also been explained on the basis of observed ion-pair association in these solutions.

Stability of Ammoniated Latex and Soap-Stabilized Emulsions in the Presence of Complex Zinc Salts

Abstract The solubility of zinc oxide in solutions of ammonia and different ammonium salts has been determined. The interaction between ammonium laurate and zinc ammine (or ethylene diammine) salts has been studied in aqueous solution, in latex, and in oil emulsions. The results indicate that destabilization of ammoniated latex or soap-stabilized emulsions by dissolved zinc oxide is due to the presence of zinc diammine ions, which form insoluble dilaurates. It is suggested that the increased rate of destabilization at elevated temperatures is most probably due to a decrease in hydration of the zinc diammine dilaurate formed at the surface of the rubber or oil particles.

Solubility of Zinc Oxide in Preserved Hevea Latex

Abstract The solubility of zinc oxide in Hevea latex, and in model solutions containing an ammonium salt together with free ammonia, has been measured by means of polarography. It is found that the solubility, at a given value of the pH, is proportional to the concentration of ammonia and ammonium salt together. At a constant concentration of ammonium ions plus free ammonia, the solubility shows a maximum at pH 9.4 A relation between the solubility of zinc oxide in Hevea latex and the concentrations of ammonium ions and free ammonia is given. The relation is checked with a number of latex samples of varying origin, and with samples produced therefrom by the addition of silicofluoride, formaldehyde, or trypsin.

The Mechanism of Gelation of Latexes

Abstract 1. The solubility of zinc oxide in ammonia and sodium hydroxide solutions was studied. In this case the presence of an ammonium salt in the system has a strong influence, and increases the solubility of zinc oxide, because the ammonium ion inhibits dissociation of ammonium hydroxide into NH4+ and OH− ions, and thus aids the formation of complex zinc-ammonium ions. We established that, in the 0–60° range, the temperature has little effect on the solubility of zinc oxide in aqueous ammonia. 2. The action of the zinc-ammonium ion on solutions of stabilizers of the soap type is explained, and it is shown that, at sufficiently high alkalinity, zinc-ammonium soaps do not precipitate from solution, but remain in a colloid state, stabilized by the alkaline soap or hydroxyl ion. 3. It is established that, in the absence of the ammonium ion, zinc oxide does not cause gelation of latexes stabilized by soaps. 4. The effect of formaldehyde on the gelation of latexes stabilized with soaps has been studied. 5. The reactions which can take place when zinc oxide is added to ammonia and alkali solutions, to ammonium and alkaline soap solutions, and to ammoniated and non-ammoniated latexes are discussed. A scheme of successive reactions which must take place during the gelation of latexes stabilized with soaps is presented.

The Heat Sensitivity of Hevea Latex II. The Process of Heat Sensitization of Degraded Latex

Abstract The heat sensitivity of a naturally or biochemically degraded latex is due in large part to the presence of amino diacids liberated by the degradation of proteins. These acids alone are capable of forming zinc ammonium complexes; however, in the case of a highly degraded latex, the monoacids with zinc oxide form soluble salts which are capable of heat coagulating this latex, the chemical stability of which has been much weakened by the desorption of the proteins. The nature of the amino acids governs the solubility of zinc oxide and, consequently, the heat sensitivity of the latex under consideration. In order to complete this work, we would have to determine the behavior of zinc-ammonium complexes in the phenomenon of coagulation, and study their dissociation in the latex. Does coagulation take place by simple neutralization of the negative particles of rubber by the Zn(NH3)4 cation, or rather, as is believed by certain Dutch chemists, does the zinc hydroxide formed by dilution of the complex act in a particular colloidal state? The problem remains unsolved.

Importance of Acidic Components in Compounding Ammonia-Preserved Latex with Zinc Oxide

Abstract In view of the experimental work described above, it appears that changes in viscosity of zinc oxide-compounded latex are due largely to the presence of ammonium salts of naturally occurring acids. These salts enable zinc to pass into solution, and to be absorbed by the latex globules, thus giving rise to the thickening commonly experienced. The amount of zinc passing into solution is directly proportional to the amount of acid present, and it is therefore suggested that determination of the acids by either of the methods described (viz., titration to pH 11 with caustic alkali, or from pH 7 to the end-point with hydrochloric acid), would form a sound basis for the classification of latices in regard to their behavior on compounding with zinc oxide. The investigations thus indicate that the variability of latex is due, in part at least, to the presence of acidic substances and may, therefore, be controlled by preventing the formation of the acids, or by their removal. Summary.—It is demonstrated that naturally occurring acidic substances control the solubility of zinc oxide in ammonia-preserved latex, and it is concluded that they are probably the controlling factor in determining the increase in viscosity which occurs in latex compounded with zinc oxide. In support of this view, it has been shown that the addition of various types of acid to ammonia-preserved latex markedly increases thickening after mixing with zinc oxide, and that the removal of naturally occurring acids reduces the thickening. It is suggested that titration of the acids in latex by the methods described forms a sound basis for the classification of latices in regard to their behavior on compounding with zinc oxide.