Purity Of Salt Research Articles

유기산에 의한 인듐스크랩에서 고순도 인듐옥살산염의 제조

Effect of organic acid on the preparation of indium-oxalate salt from indium scraps generated from ITO glass manufacturing process was studied. Effects of parameters, such as type and concentration of organic acids, pH of reactant, temperature, reaction time on indium-oxalate salt preparation were examined. The impurity removal efficiency was similar for both oxalic acid and citric acid, but citric acid did not make organic acid salt with indium. The optimum conditions were 1.5 M oxalic acid, pH 7, , and 6 hours. On the other hand, the recoveries increased with pH, but the purity decreased. The indium-oxalate salt purity prepared by two cycles was 99.995% (4N5). The indium-oxalate salt could be converted to indium oxide and indium metal by substitution reaction and calcination.

Influence of Salt Purity on Na+ and Palmitic Acid Interactions

The influence of salt purity on the interactions between Na(+) ions and the carboxylate (COO(-)) head group of palmitic acid (PA) monolayers is studied in the COO(-) and OH stretching regions using broad-band vibrational sum frequency generation (VSFG) spectroscopy. Ultrapure (UP) and ACS grade NaCl salts are used for aqueous solution preparation after proper pretreatment. The time evolution of VSFG spectra of PA monolayers on solutions made from these two grades of salts is different, which reveals that the salt purity has a significant impact on the interactions between Na(+) ions and the COO(-) group of PA. The trace metal impurities in ACS grade salt, which are more abundant than those in UP grade salt, are responsible for this difference due to their stronger affinity for the carboxylate group relative to Na(+) and further affects the interfacial water structure. These results suggest that the alkali salt grade even after pretreatment is critical in the studies of alkali cation-carboxylate interactions and comparison of relative binding affinities of different cations.

Impact of Salt Purity on Interfacial Water Organization Revealed by Conventional and Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy

Water organization and ion distribution at air/aqueous interfaces investigated by nonlinear vibrational spectroscopy as well as by other surface-sensitive techniques depend critically on the purity grade and purification processing of the chosen salts and their solutions. This is true not only for the ACS grade salts but also for the ultrapure (UP) grade, even though both have <1% impurities. It is shown here by means of conventional vibrational sum frequency generation (VSFG) and heterodyne-detected VSFG (HD-VSFG) spectroscopy that salt purity grade and pretreatment has a tremendous impact on the interfacial water spectrum of aqueous salt solutions. Our spectroscopic results indicate that salt solutions prepared from ACS and UP grade salts (NaCl, Na2CO3, Na2SO4, and (NH4)2SO4) display highly similar conventional VSFG and HD-VSFG spectra, provided that their solutions undergo pretreatment, that is, either salt baking followed by solution filtration or simply filtration for low melting point salts. In addition, untreated (NH4)2SO4 and NaCl salt solutions prepared from ACS grade salts show no significant spectral difference compared with pretreated ones. However, the corresponding untreated solutions made from UP grade salts show a remarkably higher content in organic impurities, which perturb greatly the conventional VSFG spectra in the water OH stretching region. Only in the case of high melting point halide salts such as chlorides, was it found that salt baking has an effect comparable to solution filtration. However, this was not always true for all salts, particularly those having oxyanions. Overall, to avoid spectral distortion introduced by the presence of organic contamination, it is strongly recommended that metal halide salts should be baked, yet all other molecular ion-based salts should be first baked (depending on the salt melting point), followed by filtration of their solutions before being used by VSFG spectroscopy and, most likely, in any other surface-sensitive spectroscopic studies of water organization at air/aqueous interfaces.

Culturing artificial algal mats to improve the salt yield and quality in saltworks

We carried out a program of culturing large-scale algal mats in Guangrao Saltworks, Shandong Province, China, from 1992 to 1998. The thickness of algal mats cultured by artificial inoculation for 3 years came up to 2.5 cm. Sediment microzones with diminishing redox-gradients developed under the algal mats on the test pan floors and had a strong influence on mobilizing and fixing iron. Due to the brine purification effects of the artificial algal mats, the salt purity was improved from 94.1 to 96.0%. The decrease of the brine permeation in the test pond was 60–80%. The permeation-protecting and brine purification effects created by artificial mats are very important for salt production.

Viscosity Measurements on Molten Salts with an Oscillating Cup Viscometer: Viscosity of Molten KNO3 and NaCl

AbstractAn oscillating cup viscometer interfaced to an automatic data acquisition and processing system (computer, interface, software) was built for viscosity measurements in molten salts below 1400 K.In order to avoid the “meniscus effect”, the main source of errors of the method, the measurements were carried out in the so‐called “full cup” condition, i.e. with the height of the liquid column (h) of 11.2 cm, the overall height of the cup being 11.9 cm. An adequate software supplied η values at each temperature, as function of R, I, δ, h, ρ and T values in air and with liquid containing cup. The viscosity of molten KNO3 and NaCl, both of “standard salt purity”, was reinvestigated over a temperature range of 100 K above their melting points. The standard deviation of the data obtained was ±0.38%. These data were systematically lower (3% for ηNaCl and 2% for η) than those obtained earlier by the same method, but agree within ±0.9% with the recommended Janz's “calibration quality viscosity data”.One can conclude that the method gives accurate results only if operated in “full cup” condition.