Aqueous Inorganic Solutions Research Articles

Effect of the Operating Conditions on the Oxidation Mechanisms in Conductive-Diamond Electrolyses

The electrochemical window of conductive-diamond electrodes is large enough to produce hydroxyl radicals with high efficiency, and this species seems to be directly involved in the oxidation mechanisms that occur on diamond surfaces. To verify the role of these radicals in the conductive-diamond electrolyses of organic and inorganic aqueous solutions, several experiments were carried using two well-known processes, which were selected as models: the electrosynthesis of peroxodiphosphate and the treatment of phenolic wastes in sulfate supporting media. Results show that there is an abrupt change in the efficiencies and product conversions of the processes with the anodic potential, although there is no change in the nature of the reaction intermediates or final products. Working at high anodic potentials led to very efficient processes in both cases. The changes observed have been interpreted in terms of the oxidation mechanisms involved in the process, taking into account the contribution of hydroxyl radicals for higher potentials and the formation of stable oxidants through the oxidation of the electrolyte by these radicals.

Seed layer-free synthesis and characterization of vertically grown ZnO nanorod array via the stepwise solution route

A novel stepwise method was developed for the deposition of ZnO nanorod array (NRA) from the simple inorganic aqueous solution. Different from the traditional one-pot synthesis route, merely a thin liquid precursor layer adsorbed on the substrate instead of the bulk solution underwent the reaction at elevated temperature in a typical deposition cycle. Sparse and vertically grown wurtzite ZnO NRA was deposited on seed layer-free glass substrate after 20 cycles (in typically 20 min). Each individual ZnO rod possessed the well-defined hexagonal facet, the side length of about 150 nm, the aspect ratio of 2:3, and the small size dispersity. Also the overall ZnO NRA exhibited high ultraviolet photoluminescence and weak blue emission, indicating its good optical properties. Mechanism analysis indicated that, the decrease of the supersaturation degree in solution after the climax in the reaction period of each deposition cycle is the root cause of the sparse nucleation and the vertical growth of ZnO nanorods. The work has opened up a novel stepwise approach toward high quality ZnO NRA, being valuable for extending the synthetic methods of semiconductor nanostructures in mild solutions.

Optical properties of fluids for 248 and 193 nm immersion photolithography

We present measured values of the refractive index, thermo-optic coefficient, and absorption coefficient of a number of common organic solvents and aqueous inorganic solutions that may have application in immersion photolithography at 248 or 193 nm wavelengths. The measurements were performed with a laser-based Hilger-Chance refractometer system whose design and operation are described. The optical properties of the sample fluids are compared with those of water, the currently favored immersion medium, and we discuss the potential for finding higher-index fluids that will be suitable for this application.

Evaluation of the Performance of a Newly Developed Eutectic Freeze Crystallizer: Scraped Cooled Wall CrystalIizer

Eutectic freeze crystallization (EFC) separates aqueous inorganic solutions into pure water and pure salt. By operating at the eutectic point, ice and salt can be formed simultaneously as two separate phases. The scraped cooled wall crystallizer (SCWC), specially developed for eutectic operation, is introduced. It features cooling through an outer wall combined with an internal cooling cylinder. Experiments were executed in a 1151 model SCWC using a ternary aqueous system of KN0 3 –HN0 3 . The SCWC is equipped with temperature sensors measuring bulk temperature and the temperatures of the coolant entering and exiting the cooling walls. The total heat flux from coolant to bulk equals 490-585 W m −2 K −1 at a temperature difference between cooling wall and bulk of 5–6K. At this heat flux the production capacity equals 3.8 x 10 −4 kg m −2 K −1 s −1 for ice and 3.1 x 10 −5 kgm −2 K −1 s −1 for salt. The KN0 3 crystals produced are reasonably well faceted with average size of 80–230 μm. Both ice and salt crystals are easily filtered. Impurities in the ice crystals drop below 50ppm K+-ions after three washings. Ice solid content measurements indicated that 0.01 wt% of the ice slurry consisted of entrained salt crystals. Washed salt samples contained less than 5 ppm of ionic impurities while impurity levels in the feed ranged from 50 to 500 ppm.

The Effect of Preincubation of Seed Crystals of Uric Acid and Monosodium Urate with Undiluted Human Urine to Induce Precipitation of Calcium Oxalate in Vitro: Implications for Urinary Stone Formation

Previous studies demonstrated that crystals of uric acid (UA) and sodium urate (NaU) can induce the precipitation of calcium oxalate (CaOx) from its inorganic metastable solutions, but similar effects have not been unequivocally shown to occur in urine. The aim of this investigation was to determine whether preincubation of these seeds with urine alter their ability to induce deposition of CaOx from solution and thus provide a possible explanation for discrepancy of results obtained from aqueous inorganic solutions and undiluted urine. The effects of commercial seed crystals of UA, NaU and CaOx (6 mg/100 ml) on CaOx crystallization were compared in a solution with the same crystals that had been preincubated for 3 hours with healthy male urine. A Coulter Counter was used to follow the crystallization and decrease in soluble (14) C-oxalate was measured to determine the deposition of CaOx. The precipitated particles were examined by scanning electron microscopy (SEM). The preincubated seeds were demineralized and proteins released were analyzed by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE). Analysis of (14) C-oxalate data revealed that while treated UA seeds did not affect CaOx deposition, those of NaU and CaOx inhibited the process by 51.9 (p<0.05) and 8.5% (p<0.05) relative to their respective untreated counterparts. Particle size analysis showed that the average modal sizes of particles precipitated in the presence of treated seed crystals of UA, NaU, and CaOx were very similar to those deposited in the presence of their respective untreated controls. These findings were confirmed by SEM which also showed that seed crystals of UA and NaU, untreated and treated, were attached like barnacles upon the surfaces of CaOx crystals which themselves were bigger than those precipitated in the presence of CaOx seeds. SDS-PAGE analysis of the demineralized treated seeds showed that they all selectively adsorbed urinary proteins, and perhaps other urinary macromolecules and low molecular weight components, on their surface. It was concluded that preincubation with urine, such as occurs in vivo, only slightly reduces the ability of seed crystals of CaOx, but not of UA, to cause deposition of CaOx. The most striking effect was on NaU seeds where the preincubation quite dramatically attenuated their promotory effect on the mineral deposition. This may explain the discrepancy between findings of studies carried out in inorganic solutions and undiluted human urine. This stresses the invalidity of directly extrapolating results obtained in inorganic solutions to likely effects in urine and more importantly, on stone formation.

Mathematical modeling of influence of porous structure a membrane on its vapour-conductivity in the process of membrane distillation

Membrane distillation (MD) is a perspective method of separation and concentration of inorganic aqueous solutions. The driving force of MD is temperature difference on both sides of a hydrophobic porous membrane, which separates two aqueous solutions with different temperatures and concentrations. The coefficient of vapor conductivity is one of more important parameters of water vapor transfer through hydrophobic microporous membrane. The influence of membrane porous structure on vapor conductivity coefficient was studied theoretically using the pore network as a model of porous medium. The pore networks were considered as a long and straight cylindrical capillaries arranged around the bonds of two- or three-dimensional lattices with fixed coordination number z for lognormal pore size distribution. The effective-medium theory (EMT) and smooth field approximation (SFA) were used for describing of mass-transfer through the porous membrane. It was shown that the vapor conductivity coefficient value decreases with increasing of the pore dispersion d and decreasing of mean radius porous « rå, grows with increasing of coordination number z. As a result, MD process is more effective using the porous membrane with narrow pore size distribution.

Development of a Novel Granular Detergent by Inorganic Solution Binder.

This paper discusses an optimal process for making a novel granular detergent by using an aqueous inorganic solution. This process contains a step of coating with inorganic solutions (sodium carbonate or sodium sulfate solution) onto granular detergent by spraying, which provides an improved solubility of the granular detergent as well as providing better physical properties (e.g., higher bulk density, flowability, etc.). The inorganic solutions used for the coating can also act to prevent sticking of the product. In this study, the feasibility to make better performance of granular detergent by using aqueous inorganic solutions as binder was discussed and the optimum process centerline was determined. It was also found that the Froude number could be used for the scale up/down of the coating process.

Structural investigation of water and aqueous solutions by Raman spectroscopy

Abstract In the context of a long study of the dynamical properties of water and inorganic aqueous solutions using infrared (IR) and Raman spectroscopy,we present here recent results of the influence of salt concentration on the dynamics of water molecules. The main systems studied were salts of XnYm type (where X = Li+, Na+, K+, Rb+, Cs+, Mg2+, Zn2+ and Y = Cl–,ClO4 –, NO3 –, SO4 –2). The whole spectrum reflects the molecular and ionic interactions between solvent molecules and solvent–solute and solute–solute molecules. Nevertheless, each spectral region supplies different information about these intermolecular interactions. The strong modifications in intensity and band profile undergone by the v(OH) band depends mainly on the nature of anions while cations have a weak influence. A picture of these different situations in a particular salt solution needs the support of a model of the dynamic structure of the water solvent. A discussion of the current state of the dynamical models of liquid water and new ideas on water dynamics are presented on the basis of the results obtained from the study of internal OH/OD vibrations of water in diluted mixtures of D2O/H2O. Finally, a comparative analysis of the influence on the dynamics of water molecules under the concentration of perchlorate and chloride salts of monovalent cations in water and isotopic D2O/H2O mixtures was undertaken using Raman spectroscopy.

The Solubility of Polyacrylonitrile

The comparative study of the thermodynamic solubility of PAN in five solvents led to the following conclusions: the thermodynamic solubility of PAN, characterized by the experimental and calculated cloud point curves, differ significantly for two kinds of solvents: organic aprotic and inorganic aqueous solution of NaSCN; the solubility of PAN in an aqueous solution of NaSCN is much higher than its solubility in aprotic solvents; the solubility of PAN in a number of aprotic solvents (DMF, DMAA, DMSO, DMAA + lithium chloride) differs insignificantly.

Preparation of yttria stabilized zirconia membranes on porous substrates by a dip-coating process

Gas-tight yttria stabilized zirconia (YSZ, 8 mol.% Y 2O 3) membranes with expected composition were coated on porous ceramic substrates by a dip-coating process with YSZ sol, which was prepared by ultrasonic dispersion of YSZ powder in ethanol. The YSZ powder was synthesized by co-precipitation from inorganic aqueous solutions, followed by azeotropic distillation and sintering at 600°C for 2 h. The crystalline structure of YSZ powder was characterized by X-ray diffraction. Microstructures of YSZ membranes were analyzed by scanning electron microscopy and nitrogen permeation testing. The investigation showed that defects in the membranes could be gradually removed by repeating the dip-coating procedures. The electrical transport properties of the YSZ membrane were analyzed by AC impedance spectroscopy. The electrical conductivity of the membrane was 0.001 s cm −1 at 900°C and the activation energy of electrical conductivity was found to be 87.5 kJ mol −1.

Eutectic freeze crystallization simultaneous formation and separation of two solid phases

Eutectic freeze crystallization (EFC) separates aqueous inorganic solutions into pure water and pure salt. By operating at the eutectic point, ice and salt can be formed simultaneously as two separate phases. Two aqueous systems were investigated in batch and continuous crystallization experiments: copper sulfate (eutectic temperature 271 K) and mono-ammonium phosphate (269 K). Below the eutectic temperature, ice can be formed without any salt formation by seeding with ice seeds and solely salt is formed by seeding with salt crystals. When however, the solution is seeded with both salt and ice crystals, two distinct solid phases are formed: when the stirrer is turned off, ice rises and salt settles. This shows that EFC separates aqueous solutions into ice and salt as two distinct phases. Based on these results, a 15 l cooled disk column crystallizer (CDCC) has been built, designed to crystallize and separate both the solids simultaneously in a single apparatus.

Alternative cooling fluids for use in nitration vessels

Accident reports have shown that some secondary cooling fluids are extremely dangerous if they accidentally come into contact with mixed-acid nitrating acids. A selection of water-based potential heat exchange fluids has been tested by mixing with typical nitrating acids and compared with the effects produced by adding water alone. In contrast with the explosive effects produced when methanol/water and ethanediol/water are allowed to mix with mixed acids, three aqueous inorganic solutions—magnesium nitrate, iron(III) nitrate and phosphoric acid—were found to interact much less exothermically, even less than is observed on adding the same amount of water that these solutions contain. In addition, they do not generate unstable by-products, cf. the nitrate esters formed from alcohol-based fluids, and possess the other properties required for a good secondary cooling fluid. The replacement of the currently used, hazardous cooling fluids by these alternatives is advocated.

The electrical conductivity of yttria-stabilized zirconia prepared by precipitation from inorganic aqueous solutions

The electrical conductivity of yttria stabilized zirconia (YSZ), prepared by precipitation from aqueous solutions of inorganic precursors, was measured as a function of composition, temperature of annealing prior to conductivity measurements (900°C–1700°C), and temperature of measurement (500°C–900°C). A comparison is made with the more dense YSZ prepared by the dry powder method: the conductivites are very near when the same high annealing temperatures are applied. The considerable increase in the conductivity attained by raising the annealing temperature of the precipitated material is suggested to be largely due to an increase in density. The effect of other factors is considered.

Studying in Situ Hydrothermal Reactions with X-ray Absorption Spectroscopy

A complete understanding of the oxidation state and coordination structure of inorganic species under actual hydrothermal conditions is critical to areas such as geochemistry and corrosion science. However, fundamental studies on the chemistry of inorganic aqueous solutions at elevated temperatures are scarce. Such information is also of importance in the treatment of waste slurries, including processes such as drying, calcining and vitrification. X-ray absorption spectroscopy (XAS) can provide information on bond distances and their strength or covalency, the coordination symmetry around a central atom and its oxidation stateJ '2 All of these properties are subject to change during chemical changes at hydrothermal conditions. Indeed, in our previous XAS studies we were able to gain valuable information on the solvation environment of electro-

Hans P. Eugster Memorial Symposium

Six of the nation's most outstanding geochemists and petrologists convened May 6, 1988, to honor the late Hans P. Eugster at a symposium organized by the Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Md. (see photo). Over 100 of Hans' collegues, students, and friends gathered to pay tribute both to a man they fondly remebered and to the lesson offered by his scientific career—that profound discoveries follow from the application of fundamental chemical principles to geological processes. The hour‐long presentations were a good mix of current research and reminiscences about the development of now time‐honored practices in goechemistry.Harold C. Helgeson (Department of Geology and Geophysics, University of California at Berkeley) intrigued the symposium with his vision of future developments in theoretical organic geochemistry. He outlined how equations of state for inorganic aqueous electrolyte solutions may be extended to dissolved aqueous organic species. Already, these new developments enable a quantitative analysis of goechemical processes that invlove both inorganic and organic species in solution. Examples include the generation and maintenance of the oxidation states of oil‐field brines, the migration and accumulation of petroleum, and abiologic processes involving hydrothermal fluids in the origin of life. He suggested that redox reactions involving acetate may control hydrothermal transport and precipitation of petroleum in sedimentary basins. Oil accumulations, Helgeson speculated, could be regarded as just another kind of hydrothermal “ore deposit.”

ChemInform Abstract: STUDIES ON SINGLET OXYGEN IN AQUEOUS SOLUTION. PART 1. FORMATION OF SINGLET OXYGEN FROM HYDROGEN PEROXIDE WITH TWO‐ELECTRON OXIDANTS

Chemischer InformationsdienstVolume 16, Issue 39 Physical Inorganic Chemistry ChemInform Abstract: STUDIES ON SINGLET OXYGEN IN AQUEOUS SOLUTION. PART 1. FORMATION OF SINGLET OXYGEN FROM HYDROGEN PEROXIDE WITH TWO-ELECTRON OXIDANTS D. F. EVANS, D. F. EVANSSearch for more papers by this authorM. W. UPTON, M. W. UPTONSearch for more papers by this author D. F. EVANS, D. F. EVANSSearch for more papers by this authorM. W. UPTON, M. W. UPTONSearch for more papers by this author First published: October 1, 1985 https://doi.org/10.1002/chin.198539022Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume16, Issue39October 1, 1985 RelatedInformation

ChemInform Abstract: ENERGY COMPONENT ANALYSIS FOR DILUTE AQUEOUS SOLUTIONS OF LITHIUM(1+), SODIUM(1+), FLUORIDE(1‐), AND CHLORIDE(1‐) IONS

Chemischer InformationsdienstVolume 15, Issue 20 Physical Inorganic Chemistry ChemInform Abstract: ENERGY COMPONENT ANALYSIS FOR DILUTE AQUEOUS SOLUTIONS OF LITHIUM(1+), SODIUM(1+), FLUORIDE(1-), AND CHLORIDE(1-) IONS J. CHANDRASEKHAR, J. CHANDRASEKHARSearch for more papers by this authorD. C. SPELLMEYER, D. C. SPELLMEYERSearch for more papers by this authorW. L. JORGENSEN, W. L. JORGENSENSearch for more papers by this author J. CHANDRASEKHAR, J. CHANDRASEKHARSearch for more papers by this authorD. C. SPELLMEYER, D. C. SPELLMEYERSearch for more papers by this authorW. L. JORGENSEN, W. L. JORGENSENSearch for more papers by this author First published: May 15, 1984 https://doi.org/10.1002/chin.198420011Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue20May 15, 1984 RelatedInformation

ChemInform Abstract: TRANSORT IN AQUEOUS SOLUTIONS OF GROUP IIB METAL SALTS AT 298.15 K. PART 1. ISOTHERMAL TRANSPORT PROPERTIES OF CADMIUM IODIDE

Chemischer InformationsdienstVolume 8, Issue 50 Physical Inorganic Chemistry ChemInform Abstract: TRANSORT IN AQUEOUS SOLUTIONS OF GROUP IIB METAL SALTS AT 298.15 K. PART 1. ISOTHERMAL TRANSPORT PROPERTIES OF CADMIUM IODIDE R. PATERSON, R. PATERSONSearch for more papers by this authorJ. ANDERSON, J. ANDERSONSearch for more papers by this authorST. S. ANDERSON, ST. S. ANDERSONSearch for more papers by this author R. PATERSON, R. PATERSONSearch for more papers by this authorJ. ANDERSON, J. ANDERSONSearch for more papers by this authorST. S. ANDERSON, ST. S. ANDERSONSearch for more papers by this author First published: December 13, 1977 https://doi.org/10.1002/chin.197750026Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume8, Issue50December 13, 1977 RelatedInformation

Chlorination of sulfur dioxide in a plasma arc photochemical reactor: Part II. Chlorination of sulfur dioxide

AbstractThe photochemical chlorination of sulfur dioxide was investigated experimentally. The photochemical reactor was the vortex‐stabilized arc radiation source described in Part I. Aqueous inorganic solutions, providing selective wavelength filtration, were circulated through the inner annular region. The outer annulus served as the reaction volume. The dependence of the reaction on wavelength, reaction gas inlet temperature, pressure, and reactant flow rate was investigated. The amount of sulfur dioxide in the mixture was varied from 1/6 to 2/3 atmosphere. The photochemical rate of formation of sulfuryl chloride is best described by the rate expression: where J is the volumetric rate of light absorption and where k0 and E have values of 0.0542 s1/2 and −2.6 kcal/gmol, respectively.

A new test object for evaluating resolu- tion in serial angiography.

Recent advances have led to increasing emphasis on angiography of vessels 0.3 mm or less in diameter (1–3). Unfortunately, there are many problems peculiar to roentgenography of small objects; e.g., vessels appear as much as 0.4 mm larger than their true size in conventional angiography and may be distorted in shape (4, 5). Roentgenographic interpretation is complicated by these effects, so their quantitative evaluation isof clinical importance. In our studies we developed test “vessels” of calibrated sizes, filled with typical contrast media such as Renografin-60. These devices have been used in three ways: to compare potential resolution of alternative technics, to verify resolution actually achieved in practice; and to study distortion effects. Because the preparation of these test objects presented several unexpected problems, we shall discuss their design and construction in some detail. I. Basic Design Considerations Because of considerable scatter in abdominal and cerebral angiographic studies, we simulated tissue with water in plastic tanks (Fig. 1). The test objects consisted of Renografin-60-filled tubes in paraffin blocks. A. Test Object Materials: In conventional and enlargement angiography, the photon spectra of the exit beams range roughly from 33–85 and :33–110 keV, respectively. This consideration dominates the choice of test object materials. For an accurate simulation of the true situation, we used a conventional radiographic contrast agent: Renografin-60. This is a 60 per cent aqueous solution of an iodinated methylglucaminc derivative with chemical stabilizers. Its x-ray attenuation contrast in tissue is essentially the same as that of 0.29 g iodine element per milliliter solution in water since its other chemical elements are essentially water-equivalent in the energy range involved. Other materials considered were inorganic aqueous solutions and metal wires. Most inorganic iodine or barium compounds have limited solubility, as well as other disadvantages. Salts are also generally low in solubility, except for barium iodide which is soluble but costly. Metal wires offer obvious fabrication advantages. However, they match the attenuation of 0.3 g of iodine/ml poorly for both density and atomic number reasons (Fig. 2); hence, they were excluded in this rather demanding application. We excluded various plastic and rubber tissue substitutes for practical reasons, although such materials could be considered as possible alternatives in future developments. It is evident from Figure 2, however, that the substitution of paraffin for water does not significantly alter Renografin-60 subject contrast in the photon range of major interest (above 33 keV).