摘要:

The fundamental equations for calculating the extent of separation are given for countercurrent multistage systems operated at either zero reflux, partial reflux, or total reflux. With the component distribution coefficients assumed constant, simple expressions for the maximum extent of separation are derived. The calculations clearly show how multistaging and reflux influence component separation.

ISSN:0037-2366    

DOI:10.1080/00372367008057943

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

An analytical NMR spectrometer has been used to measure line widths of molecules adsorbed on silica so as to investigate the capabilities and limitations of such measurements. Comparisons of line widths with transverse relaxation times (T2) for the same samples showed that the observed resonance lines were inhomogeneously broadened. Consequently, line widths are not a reliable way of obtainingT2values or activation energies. The porosity of silica appeared to be an important factor governing adsorbate line widths, the narrowest lines being observed with adsorbents having the largest pore diameters. The narrow resonance lines observed for molecules adsorbed at low coverages on pyrogenic silica have been attributed to the nonporous surface, small particle size, and high purity of that adsorbent. Broadening of lines at high surface coverages on pyrogenic silica appeared to be due to slow exchange of molecules between surface and bulk states having different chemical shifts. Potential applications of high-resolution NMR to the study of gas-solid adsorption are outlined.

ISSN:0037-2366    

DOI:10.1080/00372367008057944

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

High-resolution NMR spectra were taken of molecules adsorbed on silica to determine the effects of specific surface interactions on line widths, chemical shifts, equilibria, and freezing points. Line widths were measured for cyclohexane, benzene, acetone, and methanol adsorbed at monolayer coverage. Hydrogen bonding to the surface was evident for the latter two compounds from the decrease in line width when the silica was silanized. In addition, the hydroxyl hydrogen of methanol was found to undergo exchange with the surface. After silanization, chemical-shift changes were noted for cyclohexane,p-xylene, mesitylene, acetone, and methyl acetate. Attempts were made to explain the magnitude of the changes by comparison with data from infrared spectroscopy and gas-solid chromatography. Chemical shifts of mixtures of adsorbates were studied to gain additional information on relative adsorption strengths. The tautomeric equilibrium of adsorbed acetylacetone was measured from the relative integrated intensities of the keto and enol resonances. The enol form was favored more on silanized silica than on hydrated silica. Relative intensities were also used to study the freezing of adsorbates.

ISSN:0037-2366    

DOI:10.1080/00372367008057945

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The stochastic theory of chromatographic kinetics is extended in two directions: (a) To include diffusion effects, and (b) to treat then-site adsorption problem. In the first case we show that the solution to a first passage problem yields the moments of residence time in the mobile phase in a rather simple form. For the second problem we show that the central limit theorem allows us to deduce rather general results about the distribution of residence time.

ISSN:0037-2366    

DOI:10.1080/00372367008057946

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A high flux anisotropic (“skinned”) protein concentrating membrane made of cellulose acetate is described. Its method of preparation is given and the influence of the thickness of the membrane on its flux determined. The membrane's characteristics under different pressures and when ultrafiltering protein solutions of varying concentration are studied. A slightly denser variant of the same membrane, useful for the concentration of some of the smaller pathological serum proteins, is also described. The characteristics of both new membranes are compared with those of some of the commercially available membranes.

ISSN:0037-2366    

DOI:10.1080/00372367008057947

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The partition ratioDof Al(III) between aqueous chloride/bisulfate solutions of constant ionic strength (5.0) and methyl ethylketone (MEK) or methyl isobutyl ketone (MIBK) was investigated radiometrically as a function of the chloride/bisulfate ratio and aqueous acidity. With MIBK, the plot ofDvs chloride/bisulfate showed a maximum. Results may be explained by assuming the extraction of the following species: KtH+·AlCl4-, KtH+-AlCl2(HSO4)2- and KtH+·Al(HSO4)4, where KtH+represents a solvated hydrogen ion. Formation constants for these complexes were calculated.

ISSN:0037-2366    

DOI:10.1080/00372367008057948

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0037-2366    

DOI:10.1080/00372367008057942

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor