Electrolytes of alkaline zincate, acidified zinc sulphate, zinc-ammonia, zinc-ammonia-EDTA, zinc-EDTA/NaOH have been examined in order to verify their applicability for electrodeposition (ED) of zinc on stainless steel (SS) disc at ppm level. Operating parameters suitable for ED of zinc at 90% deposition (amount of zinc removed from plating solution) on SS disc using a total 1 ppm zinc in a 5 cm3 bath volume were determined. It helped to prepare radioactive source (65Zn) using inactive Zn as carrier. Speciation of zinc in a Zn-oxalate-EDTA-ammonia bath has been computed.
Authors:D. Medvedev, L. Mausner, G. Meinken, and S. Kurzak
A procedure for recovery of 65Zn from acidic Ga-rich solutions generated in 68Ge production process was developed and implemented in a “hot cell” environment. A one step simple separation was carried
out on anion exchange column filled with Biorad AG1-X8 resin. With 65Zn recovery yields of more than 95% this procedure is currently routinely used at Brookhaven Linac Isotope Producer.
Authors:M. A. Henaish, S. A. Olofa, M. M. Barakat, and T. Tawfik
A series of samples in the system Ni0.65Zn0.35CuxFe2−xO4 (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by the usual ceramic technique. Seebeck coefficient, d.c. resistivity, activation energy, drift mobilityΜ and time constant measurements are presented for all samples. As expected, the activation energies were lower for samples of higher conductivity and mobility.
The scheme of the shaft process of simultaneous zinc and lead production is shown. The residence time distribution of zinc
vapour leaving the furnace is measured using65Zn. The distribution curve is determined by deconvolution procedure of convolution integral which connects the input function,
impuls response and output function. The analysis of this curve showed that in the furnace an internal zinc recirculation
connected with secondary oxidation of zinc vapour takes place in the upper zone of the shaft. The localization of the secondary
oxidation zone and the degree of zinc reoxidation was determined.
Authors:S. A. Olofa, A. Tawfik, M. M. Barakat, and M. A. Henaish
A series of samples of the type Ni0.65Zn0.35CuxFe2−xO4 (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by means of a ceramic technique. The existence of a single phase was confirmed in X-ray studies. The dielectric constantK and dielectric lossD were measured at different temperatures at a frequency of 1 kHz. The pronounced increase in the dielectric constant at the transition temperature is due to the phase transformation from the ferrimagnetic to the paramagnetic state. The decrease in the dielectric loss with temperature is due to the reduction in the relaxation time of the hopping electrons and holes. The Tawfik constant was calculated in the ferrimagnetic state and was found to be correlated to the dielectric constant.
A series of samples in the system Ni0.65Zn0.35CuxFe2−xO4 (x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by the usual ceramic technique. X-ray analysis showed that they were cubic spinel (single phase). Young's modulus, the dielectric loss and the change in capacitance under mechanical stress were measured for the samples. Young's modulus decreased with increasing Cu content. This is due to the fact that Cu2+ ions entered the lattice substitutionally for Fe3+ ions at the octahedral sites, creating lattice vacancies gave rise to lattice strain.
The bioaccumulation of zinc byPoecilia reticulata from water as well as the elimination of the metal previously absorbed were determined by using65Zn as radioactive tracer. The exposure time varied from 18 days to 30 days. The results obtained show that the absorption and elimination of zinc byPoecilia reticulata is slow, 30 days being necessary for the elimination of 70% of the previously absorbed zinc. The same experiment was also carried out by feeding fish with65Zn contaminated food. The results obtained show that in 30 days only 40% of the zinc previously absorbed is eliminated by the fish.
Supplemental zinc as ZnO is routinely added to nursery pig diets at 15 to 20 times the nutritional requirement to alleviate
physiological stress and enhance performance. The mechanism by which Zn accomplishes this function is unknown, however, high
concentrations of Zn are excreted in the environment at undesirable levels. To study Zn uptake, we developed a multi-stage
digestion model followed by exposure to swine intestinal brush border membrane vesicles (BBMV). We report on the feasibility
of using a duel label (65Zn and 69mZn) to simultaneously quantify the competitive uptake of Zn from co-existing zinc supplements using our BBMV model.
A radiochemical charged particle activation procedure has been developed for the production and separation of the carrier free radioisotopes,65Zn and66,67,68Ga. The carrier free radioisotopes produced by the irradiation of a pure copper foil with 50 MeV -particle beam through the nuclear reactions, (, pxn), (,pxn) and (,xn), have been quantitatively separated from the activated copper matrix from an aqueous hydrochloric acid and an alkaline solution using the liquid cation exchanger HDEHP, as an extractant. Detection of different radionuclides in the activated copper target and verification of their purity at different stages of their LLX separation have been performed by -ray spectrometric studies.
Authors:M. M. Barakat, M. A. Henaish, S. A. Olofa, and A. Tawfik
A series of samples of the system Ni0.65Zn0.35CuxFe2−xO4 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) are prepared by the usual ceramic technique. X-ray analysis shows that they are cubic spinel (single phase). The lattice parameter, theoretical density (Dx), bulk density (D) and the porosity (P) are measured for the samples. The vacancy concentration of oxygen is an important parameter in the sintering process of spinel ferrites. The decrease in the population of Fe3+ ion in the octahedral sites with the introduction of Cu2+ results in the decrease of lattice parameter. The DTA tracing shows a strong exothermic peak at 90°C.