New procedure for the gravimetric determination of either phophorus or magnesium was proposed. In this procedure, the magnesium ammonium phosphate (MAP) is filtered on glass filter, and then in this state it is ignited to the magnesium pyrophosphate (MPP) at 570-590°C. In order to compare the new procedure with the ordinary gravimetric procedure, 10 samples of the MAP precipitated from a certain ammonium phosphate solution were adopted for each procedure, and the operation was examined from the beginning of the filtration of the MAP to the ending of the weighing of the MPP. Results were as follows. (1) Estimated value of the new procedure agrees with that of the ordinary. (2) Hours required for the two procedure are nearly equal, but actual working hours for the new procedure is 1/3 of that of the ordinary. (3) The standard deviations of the estimated value in the new procedure and the ordinary are 1.34 ppt and 1.68 ppt to the arithmetic mean, respectively. The new procedure offers much saving in time and tedium over the ordinary gravimetric procedure, and is more precise.
In concentrating sea water with ion exchange membrane method, relations between degrees of desalting and composition of brine particularly concentrations of scale-forming components at concentrating interfaces of membranes were studied. Experiments were carried out in systems. consisting of divalent hardly permeable (“permselective”) membranes to only anion and to both anion and cation. The decreasing behaviors of ions in desalted solution started from sea water were shown graphically by ratios of corrected concentration of each ion in desalted solution to that in sea water (“residual ratios”). At a degree of desalting on individual curves in the graph, ratios of products of differences from unity and concentrations of the ions in sea water gave concentration ratios of the ions in brine, and ratios of products of inclines of tangents and concentrations of the ions in sea water gave-ratios of the ions migrated through the membrane. Both concentrations of calcium carbonate and calcium sulfate at concentrating interfaces of anion exchange membrane increased prominently with increasing degree of desalting. These were consistent with practical observation of scale deposition, and seemed to show that partial over-desalting might be. one of important causes of scale deposition at membrane surfaces. The other prominent in reasing tendency of concentrations of scale-forming components was recognized when “permselective” membranes were placed near each other in a concentrating compartment. This seemed to suggest important problems on scale deposition in future. Changes of composition of brine with changes of degree of desalting were delt well with improved expression of permselectivityin more than 0.2 in “residual ratio” of sodium ion or chloride ion. Then, composition of solutions at concentrating interfaces of membranes could be calculated in this range of degree of desalting. It seemed to be necessary hereafter to characterize membranes with manner of changing results with changing operating conditions in electrodialysis.
The author conducted a study on the adsorption behavior of yttrium and rare earth elements in sea water. These elements adsorbed themselves to glass or polyethylene and to suspended partides from the solution of pH5 to 8. Sample water, therefore, should be kept acidic (pH<3) after sampling. As a result of fluorometric determination, sea water was found to contain about-0.15μg/lof yttrium, and above a half of the content was concerned with suspended matter. Lanthanum and europium were determined by neutron activation, and the results were-0.04μg La/l and-0.002μg Eμ/l.
Study was conducted on the relation between characteristics of membrane and preparing conditions or operation factors for desalination of salt solution with the reverse osmosis membrane from cellulose acetate-formamid-acetone system similar to Loeb. Although the evaporation process of acetone was important to the formation of thin surface layer of membrane, but the effect of it was reduced at higher temperature. The characteristics of membrane was easily controlled by temperature and the optimum was found to be about 80°C When the membrane was subjected to variation of temprature of feed solution, history phenomenon was found in flux of desalted water. This phenomenon is the similar to the case in variation of operating pressure. In sea water, the orders of ion rejection among cations and anions were Mg2+>Ca2+>Na+>K+and SO42->Cl-, respectively.