Investigation of the usefulness of NTA, EDTA and DTPA in separation of some platinum metals on cellulose exchangers.
The possibility of using NTA, EDTA and DTPA as complexing agents for separation of some platinum group ions on cellulose ion-exchangers has been investigated. The greatest differences in the affinities of Pd(II) and Pt(IV) toward the cellulose ion-exchangers are obtained in the presence of DPTA, Cellex D (as ion-exchanger) in hydroxide form. The column separation of Pd(II) from Pt(IV), Rh(III) from Pd(II) and of a Rh(III)Pd(II)Pt(IV) mixture can be achieved with DPTA and chloride solutions. The method can be for determination of the components of RhPdPt alloys.
The selective adsorption of gold (III) and palladium (II) on new phosphine sulphide-type chelating polymers bearing different spacer arms
Abstract New resins, with a functional group based on triisobutyl phosphine sulphide and containing different spacer arms between the polymeric matrix and the functional group, are evaluated in order to determine and characterise the mechanism of the metal adsorption process. These polymers are selective towards gold and palladium from other noble (Pt, Rh and Ir) and base (Fe, Cu, Ni and Zn) metals. Selectivity is higher in the case of gold (2.8 mmol Au/g resin for polymer 3 and 6.5 for polymer 4) than for palladium (0.5 mmol Pd/g resin for polymer 3 and 0.7 for polymer 4). The application of the Langmuir model to the data permits the determination of the adsorption mechanism, which we found to be a chelating process. The result shows that spacer heteroatoms become involved in the adsorption process. The kinetics of the adsorption is faster for palladium than for gold. The elution of these two metals is accomplished by the use of sodium nitrite and thiourea as eluting compounds.
A new method of near field analysis
The problem of the accurate determination of the total electromagnetic field produced by a current distribution on a circular disc type aperture is examined. For comparison of the near and Fresnel region solutions, an exact Maxwellian integral is used as the starting point. Aperture and space coordinates are separated by the use of Bessel function addition theorems, allowing the field to be expressed as a sum of terms containing radial and angular integrals. The radial integrals involve only the disc (aperture) distribution and coordinates while the angular integrals involve only the elevation angle. The distance from origin appears implicitly in the series coefficients. These integrals are suitable for high speed computations and have been evaluated for a number of cases. The results are compared with the small angle and general Fresnel formula values for various observation angles, distances from the aperture, and aperture distributions.