Separation of Mn and Zn from Co and Ni by fractional dissolution of their sulfides

1960 ◽  
Vol 37 (8) ◽  
pp. 412 ◽  
Author(s):  
Richard B. Hahn ◽  
C. H. Sanders ◽  
George Gutnikov
Keyword(s):  
Fractional Dissolution

Fractionation of Rubber

1941 ◽  
Vol 14 (1) ◽  
pp. 1-14 ◽  
Author(s):  
George F. Bloomfield ◽  
Ernest Harold Farmer
Keyword(s):  
Molecular Weight ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
The Other ◽  
Major Fraction ◽  
Low Concentrations ◽  
Fractional Dissolution ◽  
Judicious Choice ◽  
Hydrocarbon Molecules ◽  
Soluble Fractions

Abstract Latex rubber which has been purified to the point at which it contains an insignificant amount of nitrogen can be separated by fractional dissolution in a mixture of petroleum and acetone into a series of hydrocarbon fractions of decreasing solubility and increasing molecular magnitude. All these fractions except the highest are soluble in petroleum and in benzene. Crepe rubber, on the other hand, appears invariably to contain a small, most-soluble fraction of oxygenated rubber, and a small similar quite insoluble fraction of material of high molecular weight. Between these extremes the rubber can be divided into fractions of increasing molecular weight, although, up to the present, about 70 per cent of the total rubber has appeared in a single fraction. It may be possible later, by judicious choice of another pair of solvents, to resolve this major fraction into a series of subfractions. Kemp and Peters refer to the effect of polar nonsolvents in reducing the viscosity of rubber solutions and also in assisting to bring gel rubber into solution, phenomena to which the polar molecules conceivably contribute by countering the forces of association between the rubber molecules. The present series of fractionations was conducted throughout in the presence of a polar nonsolvent (acetone), and hence may be considered to approach towards a separation of true rubber molecules as distinct from molecular aggregates. It is found, however, that, whereas the more soluble fractions of acetone-extracted crepe rubber contain small proportions of nitrogen, the least soluble fractions contain substantial proportions. Any effect which the nitrogenous material may have in assisting to link together hydrocarbon molecules to which it is attached, i. e., in contributing to the high-molecular condition of a portion of natural rubber, remains at present uncertain in character. The fractions of rubber, and especially the higher ones, show a strong tendency to become insoluble when they have once been freed from the last traces of solvent. It seems doubtful whether the decreased solubility is due to oxygen as it would require to be effective at exceedingly low concentrations.

scholarly journals Fractional Dissolution of Polyelectrolyte

1961 ◽  
Vol 64 (9) ◽  
pp. 1641-1642
Author(s):  
Akira Takahashi ◽  
Ikumi Kagawa
Keyword(s):  
Fractional Dissolution

STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES: LX. STABILIZING ACTION OF ETHANOL ON STARCH NITRATES

1946 ◽  
Vol 24b (5) ◽  
pp. 238-245 ◽  
Author(s):  
W. R. Ashford ◽  
L. M. Cooke ◽  
Harold Hibbert
Keyword(s):  
Molecular Weight ◽  
Nitrogen Content ◽  
Corn Starch ◽  
Insoluble Residue ◽  
Low Molecular Weight ◽  
Fractional Dissolution ◽  
Dual Action ◽  
Explosive Properties ◽  
Soluble Fractions ◽  
Insoluble Portion

Fractional dissolution has been applied to nitrated corn starch with the consequent removal of ethanol-soluble fractions. Hot and cold ethanol-soluble fractions have been removed in this way amounting to from 10 to 25% of the crude nitrate. The ethanol-soluble fractions, consisting of low-molecular weight and low nitrogen-content material, are not stabilized by ethanol. The insoluble portion is greatly stabilized as a result of the ethanol treatment.The insoluble residue left after ethanol treatment of crude starch nitrate possesses good explosive properties, a high nitrogen content, and high stability. The stabilization of starch nitrate by ethanol is shown to be the result of a dual action, namely, (a) removal of highly unstable material of low molecular weight and nitrogen content, and (b) the conferring of increased stability by some, as yet unknown, mechanism on the insoluble portion.

UO2. Matrix Dissolution Rates and Grain Boundary Inventories of Cs, Sr, and Tc in Spent Lwr Fuel

1990 ◽  
Vol 212 ◽  
Author(s):  
W. J. Gray ◽  
D. M. Strachan
Keyword(s):  
Grain Boundary ◽  
Dissolution Rate ◽  
Experimental Methods ◽  
Light Water Reactor ◽  
Spent Fuel ◽  
Light Water ◽  
Fractional Dissolution ◽  
Flow Through ◽  
The Individual ◽  
Individual Grains

ABSTRACTExperimental methods have been developed for measuring the grain-boundary inventories of radionuclides and for determining whether the UO2 matrix of spent light-water reactor fuel dissolves congruently. Both methods depend upon first separating the fuel into individual grains. With the grain boundaries thus exposed, the associated inventories of radionuclides can be completely dissolved and measured. To determine whether the UO2 matrix of spent fuel dissolves congruently, the fuel grains were placed in a flow-through column and water was pumped through the column at a rate sufficient to maintain the concentration of U in the column effluent far below saturation. Once the grain-boundary material has dissolved, the forward dissolution rate of the UO2 matrix can be measured and, by measuring the concentrations of other radionuclides in the column effluent, the degree of congruency of the dissolution process can be determined. Data obtained to date indicate that the grain-boundary inventories of Cs, Tc, and Sr are approximately equal to gap inventories and that the fractional dissolution rate of Cs from the U02 matrix is approximately equal to that of U, i.e., the Cs and U dissolved nearly congruently. In addition, the data appear to show a gradient in the concentrations of Cs and Sr across the individual UO2 grains.

scholarly journals FRACTIONAL DISSOLUTION CURVES OF NITRATED PULPS WITH ETHYL ACETATE-ETHANOL MIXTURES

1959 ◽  
Vol 15 (4) ◽  
pp. 271-275
Author(s):  
Osakazu Nakao ◽  
Makoto Usuda ◽  
Nobuhiko Migita
Keyword(s):  
Ethyl Acetate ◽  
Fractional Dissolution

scholarly journals FRACTIONAL DISSOLUTION CURVES OF NITRATED PULTS WITH ETHYL ACETATE-ETHANOL MIXTUTES

1959 ◽  
Vol 15 (3) ◽  
pp. 175-181
Author(s):  
Osakazu Nakao ◽  
Hideaki Okumura ◽  
Nobuhiko Migita
Keyword(s):  
Ethyl Acetate ◽  
Fractional Dissolution
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