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Abstract
Sorption of cesium from nitric acid medium by potassium nickel hexacyanoferrate, KNiFC, was investigated using the batch technique. The effect of hydrogen ion concentration on the distribution coefficient of cesium has been studied in the pH range 1–5.5. The effect of particle size, the temperature on the sorption equilibrium and rate of uptake of cesium were investigated. The temperature effect on both sorption equilibrium and rate of uptake was found to be limited. The kinetic study shows that the sorption is controlled by particle diffusion mechanism. The diffusitivity of cesium ions into different particle sizes of KNiFC, the activation energy, and the entropy change of the sorption process were calculated. The effect of the presence of cobalt ions on the equilibrium and the rate of uptake of cesium is presented.
Abstract
The extraction of Nd3+ and Eu3+ from aqueous media containing selected diamine ligands by HDEHP solution in benzene has been investigated. It is found that the presence of the diamine in the aqueous phase enhances the extraction of both Nd3+ and Eu3 in the organic phase. The possible explanation for this behaviour is presented and a mechanism based on extraction of an adduct of the type MH3(DEHP)6. B is found to be the most probable.
Abstract
The effect of ten pure diluents and different mixtures of nitrobenzene and toluene on the synergic extraction of Co2+ by the thenoyltrifluoroacetone (HTTA)-tribenzylamine (TBA) mixture is studied. The logarithm of the extraction constant of Co(TTA)2 increases with increasing dielectric constant of the diluent, whereas the logarithm of the formation constant of the extracted adduct Co(TTA)2TBA decreases with increasing dielectric constant of the diluent. This behaviour is explained by changes in the hydrophobic character of the extracted species. The theory of regular solutions is successfully applied to the extracted adduct. Consideration of the self-association of the amine salt is necessary in the treatment of the equilibria involved.
Abstract
Fission-produced 131I and 103Ru radionuclides have been separated sequentially by distillation from H2SO4 of controlled chemical composition. The thermal-neutron irradiated uranium trioxide targets were digested in 2M NaOH solution and then, the supernatant solution was acidified to 20% H2SO4 with addition of a few drops of H2O2 solution. On boiling for 3.5 hours, ≥99.99%131I was volatilized, passed through 3M H2SO4 traps, and then collected in 0.1M NaOH + 0.01% Na2S2O3 solution with a recovery yield of 73.6%. The product radionuclide had high radiochemical and radionuclidic purities. After separation of 131I, the fission-product solution was acidified to 40% H2SO4 acid containing KMnO4 as an oxidant and boiled for 40 minutes. Ruthenium nuclides were volatilized and collected in 0.1M NaOH solution. Gamma-ray spectrometry showed that the separation and the recovery yields of 103Ru were ≥99.99 and 65%, respectively, with ~92% radionuclidic purity, measured immediately after separation. The radionuclides of 132I and 106Rh were the main contaminants detected in the obtained 103Ru product solution.
The deterrent and toxicity effects of Melissa officinalis L. essential oil on Tetranychus urticae Koch were studied under laboratory conditions. Leaf discs treated with increasing concentrations of lemon balm oil showed high percentage of repellency (64–86%), respectively. The oviposition deterrent indices (ODI) of Melissa oil was ranged (74–94%) for T. urticae at concentration (0.3–1%). The direct contact application of M. officinalis oil proved to be the most toxic application on various stages of T. urticae compared to leaf dipping, fumigation and systemic applications. Oil formulation (Melissacide) was shown to be the effective one against T. urticae nymphs, females and eggs (LC50 = 0.03, 0.03 and 0.04%) compared to Melissa oil.The toxicity of M. officinalis oil and Melissacide by direct spray to females and eggs of the predatory mite Neoseiulus californicus (McGregor) was tested. The predator N. californicus is extremely less sensitive to Melissa oil and Melissacide than the pest T. urticae in the laboratory. When N. californicus was sprayed with (LC50 and LC90 values reported on T. urticae), females mortalities ranged between 8.5–13%, respectively. Melissacide is non-persistent in the environment due to its volatile nature. No phytotoxicity was observed in bean plant after four weeks of Melissacide treatment.Results obtained chemically from M. officinalis oil, may suggest that the higher percentage of benzene, 1(1,5dimethyl-4hexenyl)4methyl (= α-curcumene), caryophyllene oxide, ëCadinol and cedrene of the oil could be responsible for the toxic effect.
Seed-bone infection level of watermelon with F. oxysporum f. sp. niveum has a significant effect on wilt incidence. When high (23-31.5%) or moderate (8.5-9.5%) seed-borne infection occurred, wilt incidence reached up to 47.5-57.5% and 45-55%, respectively. However, when low (1.5-2.5%) seed borne levels occurred wilt incidence did not increase more than 5-10%. It is recommended to use seeds of free or low infection levels of Fusarium to minimize watermelon wilt incidence.
Summary
Barium-137m radioisotope generator of the chromatographic column elution mode based on loading 1.5 g 6-tungstocerate(IV) gel matrix with ~54 kBq of fission-produced 137Cs is described. The elution performance of the generated 137mBa radionuclide was investigated as a function of chemical composition of the eluent, flow rate, elution frequency, and age of the generator system. At comparable conditions, 137mBa eluates with 0.9% NaCl-0.1M HCl eluent had higher elution yields and radionuclidic purity than with 0.1M NH4Cl-0.1M HCl eluent. The generator has been repeatedly eluted for 311 days by passing 4810 ml of the saline eluent (10 ml × 481 elution operations) at a flow rate of 3.0 ml/min. Barium-137m eluates of high and reproducible elution yields, chemical and radionuclidic purities of (≥ 99.99%) were obtained.
Summary
Ruthenium-106 and 137Cs have been separated from thermal-neutron irradiated UO3 targets aged for ~2.5 years by distillation and surface interactions in nitrate media of controlled chemical composition. After digestion of the aged targets with their aluminum wrapper in 2M NaOH solution, nitric acid was added to complete dissolution of the formed residue. The prepared fission product solution was separated from 129I and 91.8% 106Ru by sequential distillation from 20% and 40% HNO3 solutions containing H2O2 and KMnO4, as oxidants, and by boiling for 4 and 2.5 hours, respectively. The recovery yield of 106Ru collected in 0.1M NaOH solution was ~68.2% with a radionuclidic purity of ³99.99%. Thereafter, the fission product solution was brought to pH 9.5 by addition of NaOH solution to precipitate Al(OH)3, MnO2, and Na2U2O7 which selectively retained the remaining fission products leaving, mainly, 137Cs in the supernatant solution. The recovery yield of 137Cs was ≥97.3% with ~99.75% radionuclidic purity. The gamma-ray emitter contaminants which could be detected and identified in the recovered 137Cs solution, were ~0.25% 134Cs and ~1.4 . 10-3% 152,155Eu.
