In Japan, common table salt has been manufactured by evaporating concentrated seawater (i. e., nic brine), produced by electrodialysis using ion-exchange membranes, since 1972. The present dy was conducted to obtain fundamental data on the treatment of ionic brine and its bittern salt factories. The compositions of ionic brine produced at various Japanese salt factories and laboratories re examined and their properties clarified. Solubility equilibria for a quinary system of Na+, K+, Mg2+, Ca2||Cl--H2O and the surrounding stems were determined by the isothermal method at 0.25, and 100°C. On the basis of the exrimental results and published data, various phase diagrams for quaternary and quinary systems re drawn. To estimate liquid composition, at NaCl saturation, for the quinary system of Na+, K+, Mg2+, Ca2+Cl--H2O, generalized equations were derived and verified by experiment. A new metho s developed to provide visual representation of the three-dimensional field of NaCl crystallization, rmally shown using tetrahedral coordinates for the quinary system, by simple triangular coordites. The validity of this method was confirmed experimentally. Graphical calculations for the isothermal evaporation of ionic brine at 25°C were made. Values changes in the liquid phase components and types of crystals deposited were found to be fficiently reliable by comparison with experimental data. A method of graphical calculation was devised for the treatment of ionic brine in salt factories, th respect to salt deposition by the evaporation of ionic brine and cooling the hot mother liquor d other procedures. The application of this method to the salt manufacturing process is disssed. It was concluded that the above results provide an adequate basis for establishing optimum erating conditions for salt production from brine obtained by the ion-exchange membrane method.
Macroreticular resins (RCSP) containing phosphino and phosphono groups were synthesized from nine types of styrene-divinylbenzene copolymer beads with various physical pore structure, and the adsorption of uranium on the resins was investigated. The adsorption capacity of uranyl ion on the RCSP was in proportion to the amount of functional groups, but the adsorption ability for uranium in natural seawater was greatly influenced by not only physical pore structure but also pore structure based on the swelling. Natural seawater was passed through the column packed with the RCSP (C and G), which have the highest adsorption ability for uranium of the RCSP prepared in this study, for 40 days at a space velocity (SV) of 180h-1. Calcium and magnesium absorbed on the RCSP attained equilibrium in 5 days, while uranium adsorbed increased with the passage of time. This result indicates that the RCSP have high affinity for uranium in seawater.
Among the various sensors used for crystal growing, the consistency meter “Rheometer” is known to detect suspension density other than the degree of supersaturation. A report says that the consistency meter is unsuitable for the crystal growing in a solution in which the crystal growing speed is slow. The author defines the consistency as a value combining the solution concentration, the suspension density and their intermediate matter “houga”. The author also is advocating that the crystal growth should be controlled by controlling the amount of the “houga”. To show that the control of the “houga” amount is effective for crystal growth control, two kinds of crystal growing experiments are performed. One is the CGCR which controls the “Rheometer” value (consistency), and the other, the IGCR which controls the amount of “houga” in the “Rheometer” value. This paper reports that the “houga” amount controlling IGCR resulted, compared to the CGCR, in improvements in recovery rate and crystal quality, with shorter crystal growing speed.
In order to study the dehydration of vegetables in saline solutions, the osmotic pressure of twenty-seven vegetables and saline solutions were measured. Subsequently, dehydration of the Japanese radish, daikon, was kinetically analyzed in the solutions of different salt concentrations. The structure of the radish membrane was also observed using a scanning electron microscope (SEM). The results were as follows. The mean osmotic pressure of leaf, fruit, and root vegetables were 4.25, 7.47, and 9.62 atm, respectively. Root vegetables showed the highest osmotic pressure, while leaf vegetables showed the lowest. The dehydration process of the radish followed four stages: initial dehydration, first equilibrium period, reduction period and second equilibrium. Observations using SEM showed that the cell membranes of radish shrank and that some of the cell contact sections were torn apart by the dehydration. The dehydration process of the radish in different salt concentrations followed first-order kinetics and the rate constants were in the order of 10-2 (min-1), and the rate constants were also proportional to the surface area of the sample. From temperature dependence, the activation energy of the dehydration process was calculated at 3.5 kcal/mol. The thermodynamic properties of the process were also calculated using Eyring's equations. The activation free energy, activation enthalpy, and activation entropy were 21 to 23 kcal/mol, 3.0 kcal/mol, and-62 to-64 e.u., respectively. The activation energy and the activation free energy were rather small values and the activation entropy had negative values.
A sample salt of about 0.4g is treated with 8ml of 6M hydrochloric acid at 120°C for 30 min in a 23ml polytetrafluoroethylene decomposition vessel which is set in a stainless steel housing (UNI-SEAL), to prepare the sample solution. If residue is found in the sample solution, it is subjected to centrifuge separation and decomposition with hydrofluoric and sulfuric acids for determining undissolved aluminum. The solution is adjusted to pH 4.5 with ammonium acetate solution followed by adding small amounts of ascorbic acid. Aluminum is fluorometrically determined after adding 8-hydroxyquinoline-5-sulfonic acid. Aluminum down to about 0.2ppm is determined. Some analytical examples are given together with discussion about the effect of sodium chloride concentration and coexisting ions, decomposition of sample, and the dissolved and undis solved aluminum.
Analytical results of insoluble matter, which were determined by some different methods, were compared with each other, and discussed in relation to the results of its X-ray diffraction and fluorescence analyses. The use of a membrane filter, which was convenient for X-ray analyses, improved the precision of its determination compared with use of a glass fi1ter or Gooch crucible with a piece of filter paper as described in Japanese or ISO methods. A China salt containedquartz, plagioclase, and calcite; an Australiasalt, quartz and kaolin mineral; a Mexico salt, quartz and plagioclase; an Austria rock salt, fine and coarse anhydrite; and a Chile rock salt, magnesite, quartz, and chlorite, respectively as main components in their insoluble matter. An experiment suggested that raw salt contains some silicon and/or aluminum compounds that are insoluble in water but soluble in alkaline solution. A large difference was found between the analytical results of insoluble matter by the Japanese and ISO methods in Austria rock salt, which contained anhydrite with a limited solubility. A sample with larger calcite content left calcite in its insoluble matter, depending on dissolution procedure. The facts described above suggest that analytical results of not only insoluble matter but also soluble ions such as silicon, aluminum, calcium, sulfate,etc., may depend on conditions for sample dissolution, if the sample containsmuch substances with limited solubilities. X-ray fiuorescence analysis of the insoluble matter suggested that any trace element in salt should be determined as either dissolved or insoluble in the Strict sense.