Water-solid Interactions Research Articles

Preliminary quantification of metal selenite solubility in aqueous solutions

Selenium solubilization can be a potential source of environmental contamination in natural systems. Currently no experimental data are available on the solubility of metal selenites in aqueous solutions. The objective of our study was to determine the solubility of Ca, Mg, Mn, and Zn selenites. A dissolution study was conducted for 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35 and 40 weeks with CaSeO 3 · H 2O, MgSeO 3, MnSeO 3 and ZnSeO 3 · H 2O using different background solutions, including distilled deionized water (DI Water), 0.01 M NaCl, 0.03 M NaCl and 0.02 M Na 2SeO 3. For all solids, equilibrium was reached within 40 weeks. As compared to the theoretical values obtained from literature, the experimental p K 0 values for ZnSeO 3 · H 2O were higher, whereas for MgSeO 3 the determined p K 0 values were lower; theoretical and experimental data for both CaSeO 3 · H 2O and MnSeO 3 were comparable. A comparison of the p K 0 values also indicated that MgSeO 3 had the highest solubility in DI water, whereas in the three other solutions MnSeO 3 had the maximum solubility. The mean p K 0 values determined for CaSeO 3 · H 2O, MgSeO 3, MnSeO 3 and ZnSeO 3 · H 2O in the above mentioned background solutions were 7.76, 7.56, 7.11, and 7.70, respectively, which indicated that the overall solubility order would be, Mn SeO 3 > MgSeO 3 > ZnSeO 3 · H 2O > CaSeO 3 · H 2O. The results of this study are fundamental for modifying existing Se thermodynamic databases and understanding selenite solid-water interactions in natural environments.

Water solid interactions II. Effect of moisture sorption and glass transition temperature on compactibility of microcrystalline cellulose alone or in binary mixtures with polyvinyl pyrrolidone

The relation between the moisture sorption and compaction properties of microcrystalline cellulose, MCC, and binary mixtures of MCC with polyvinyl pyrrolidone, PVP, has been examined. PVP is a completely amorphous polymer, whereas MCC contains various fractions of amorphous structure depending not only on the quality used but also on the pharmaceutical processing. The tensile strength of tablets of MCC is shown to depend upon the relative humidity, RH, prior to compaction. At an RH of about 70%, a decrease in strength is observed corresponding to the upward shift of the moisture sorption isotherm. For a dry blend of MCC and PVP as well as for a granulation, the tensile strength is determined by the properties of MCC at humidities below 70% RH. At humidities above 70%, a reduction of the glass transition temperature of PVP below the operating temperature (20°C) is the dominating factor, resulting in a decrease in tensile strength.

Water-solid interactions: I. A technique for studying moisture sorption/desorption

Moisture sorption and desorption have been characterized for active (naproxen and paracetamol) and inactive pharmaceutical solids by using a climatic test chamber. The relative humidity (RH) of the climatic test chamber was varied in the range from 15 to 90%. Equilibrium moisture content was achieved within a period of 2 h for slightly hygroscopic and moderately hygroscopic substances. For very hygroscopic substances equilibrium was reached within 2 h at low RH (< 60%), whereas more than 24 h were needed at high RH (> 60%). Moisture sorption isotherms were characterized by using the climatic test chamber and were found to be identical with moisture sorption isotherms characterized by desiccators.

Mechanism of solid-water interaction problems during earthquakes

Solid-water interaction problems during earthquakes can usually be divided into three categories: contact, cavitation and separation. This division is made according to the earthquake intensity subjected to by the solid and water masses. In this paper, the mechanism of the solid-water separation problem and its effect on the motion of the solid and water masses are studied using a simplified two masses model. The analytical results here indicate that (1) compared to the solid-water cavitation effect, solid-water separation enlarges the separation time interval between the solid and water masses during strong ground motion; (2) solid-water separation may change the frequency of the system, and consequently the resonance of the system can be suppressed to some extent; (3) solid-water separation can reduce the dynamic water pressure on the solid mass as well as prevent any adverse effect due to cavitation.

Solid-water interaction in liquid storage tanks

This paper is concerned with ground-supported cylindrical storage tanks vibrating in an axisymmetric manner. A study has been made of the significance of horizontal excitations on the dynamic pressure distributions associated with the sloshing and bulging modes. These pressures have been calculated by using a previously obtained functional. Steel, aluminium and concrete tanks are included to study the effect of these typical tank materials. Only linear, elastic behaviour of the tank materials has been considered. The principal conclusions of the study are that reinforced concrete tanks are more susceptible to higher dynamic pressures than steel or aluminium tanks, and that the maximum dynamic pressure developed in partially filled tanks may be more critical than those for the same tank at maximum capacity.

Water-solid interactions in thermal analysis

The effects of water on the thermal analysis of several salts and minerals and the thermal hydrolysis of hydrated salts are discussed. The discussion is based on contributions which were presented at the 8th ICTA Congress. The presence of water decreases the activation energies of various thermal reactions in the solid state. The following reactions were discussed: (1) thermal loss of zeolitic and structural water; (2) thermal hydrolysis of hydrated salts; (3) the contribution of water vapour to thermal crystallization and decomposition processes; (4) contribution of water to mechanochemical processes as determined by thermal analysis.

A variational principle for a solid-water interaction system

A variational principle for a coupled dynamic system of a solid and a water field with a free surface is derived with the aid of Hamilton and Toupin's dual principles. It is helpful for better understanding solid-water interaction problems.

ChemInform Abstract: THE EFFECT OF WATER VAPOR ON CONTAMINATION OF METALLIC OXIDE SURFACES

AbstractDie Kontaminierungsgeschwindigkeiten reiner Metalloxidoberflächen (TiOz (001), Cr,O3 (0001), α‐AlzO3 (0001 ), NiO (100) und SrTiO3) durch die Dämpfe flüssigen Paraffins werden, wie Kontaktwinkelmessungen von Wassertropfen zeigen, durch koexistierenden H2O‐ Dampf stark reduziert.

The Effect of Water Vapor on Contamination of Metallic Oxide Surfaces

Abstract The contamination rates of the clean surfaces of metallic oxides by liquid-paraffin vapor are largely reduced by the coexisting water vapor. They are related to the hydrophilicity of oxides evaluated as the water-solid interaction free energy by the two-liquid-contact-angle method.

Electron spin resonance of the Mn2+ion in the study of the mobility of water adsorbed on silica gel and γ-alumina

The electron spin relaxation of Mn2+ in supercooled water adsorbed on silica gel and γ-alumina has been investigated. The correlation time for the modulation of the zero-field splitting tensor has been evaluated from the temperature and frequency dependence of the e.s.r. linewidth: τc= 1.4 ± 0.3 × 10–12 s at 25 °C has been extrapolated for bulk water solution. In the capillary adsorbed water, lineshape analysis suggests the existence of a distribution of crystal-field sites. The rate of interchange among differently relaxing sites is < 109 s–1. This suggests a long-range solid-water interaction which slows the mobility of water molecules up to 15–20 Å from the surface.