Influence of anionic surfractants on Zn2+ and Sr2+ uptake by ivy (Hedera helix L.) leaves

Surfactants are frequently used as adjuvants for improving the efficiency of foliar applied fertilizers, pesticides and other biologically active substances. In our paper we used detached leaves of ivy (Hedera helix L.) for the study of the influence of anionic surfactants sodium dodecylsulfate (SDS) and sodium dicyclohexyl sulfosuccinate (DCSS) on zinc and strontium uptake by leaf surface and transport by radiotracer technique with 65ZnCl2 and 85SrCl2. Accumulated amounts of Zn2+ and Sr2+ ions by the surface of detached intact ivy leaves were 5.0 and 1.1 μg/g, respectively. Ivy leaves pretreated for 24 h in 1 mM SDS or DCSS solutions accumulated approx. twice more Zn and five time more Sr than non treated leaves. Pretreatment with surfactants increased mobility of zinc and strontium in leaf tissues. Separate experiments showed that both SDS and DCSS were sorbed onto the leaf tissue reaching equilibrium within several hours of immersing leaf blades to surfactant solutions. The process can be described in terms of partition equilibria P = [C]leaf/[C]solution with log P = 1.396 within surfactant concentration studied Co ≤ 100 μmol/L. The mechanism of action of surfactants on metal ion uptake is discussed.

Cadmium sorption by dried plant biomass – Reversibility studies

Heavy metals such as cadmium are hazardous to biosystems and present possible human health risk. Thus, the removal of cadmium from liquid wastes is of great importance from an environmental and industrial point of view. There is a tendency to use agricultural wastes for the sorption of toxic metals as an alternative to the existing conventional technologies. The aim of this work was to describe Cd sorption and desorption equilibria by dried leaf biomass of tobacco (Nicotiana tabacum L.), hop (Humulus lupulus L.), pumpkin (Cucurbita pepo L.), sunflower (Helianthus annuus L.), cucumber (Cucumis sativus L.), pepper (Capsidum annuum L.), tomato (Solanum lycopersicum L.) and vine-grape (Vitis vinifera L.) using radiotracer technique with 109CdCl2. Cadmium sorption Q values (mg/g, d.w.) of all of plant biomass studied increased proportionally with the initial CdCl2 concentration within the range 0.01 – 10 mmol/L CdCl2. Mean sorption capacity of dried leaf biomasses of eight plants for Cd from the solution with the initial concentration C0 = 10 mmol/L CdCl2 in deionized water was Q = 213 μmol/g (d.w.). By single step desorption of Cd from leaf biomass for 30 min at 20 °C with deionized water, 0.1 mmol/L EDTA or 0.1 mmol/L HCl, up to 30 %, 85 % and 98 % of sorbed Cd, respectively, was removed. Obtained data can serve as a model for the prediction of sorption-desorption equilibria of biomass used for removing of Cd from polluted waters and Cd releasing back into waters containing other inorganic solutes. Formation of Cd2+, CdCl+, CdCl2 0, CdSO4 0, CdOH+, Cd2OH3+, Cd(OH)20 and Cd(OH)3- species in dependence on pH values and the presence of Cl- anions is also discussed.

Techniques of Tracer Diffusion Measurements in Metals, Alloys and Compounds

Tracer diffusion is one of most reliable techniques for providing basic kinetic data in solids. In the present review, selected direct methods, in particular the radiotracer measurements as a superior technique due to its high sensitivity, Secondary-Ion-Mass-Spectroscopy (SIMS) profiling, X-Ray Diffraction measurements and Rutherford Backscattering Spectrometry are presented and discussed. Special attention is put on the radiotracer technique describing the currently used sectioning techniques in detail with a focus on the experimental applications and complications. The relevant experimental results are exemplary shown. Furthermore, the most recent developments and advances related to the combined tracer/inter-diffusion measurements are highlighted. It is shown that this approach offers possibilities to provide the concentration-dependent tracer diffusion coefficients of the constituting elements in multi-component alloys in high-throughput experiments. Possibilities of estimating the tracer diffusion coefficients following different types of diffusion couple methods in binary and multicomponent systems are briefly introduced. Finally, specificity of SIMS analysis of diffusion in fine-grained materials are carefully analyzed. If applicable, a direct comparison of the results obtained by different techniques is given.

Production of no-carrier-added 89Zr at an 18 MeV cyclotron, its purification and use in investigations in solvent extraction

The chemical separation of zirconium from lanthanides by liquid–liquid extraction is challenging but critical for medical and technological applications. Using the example of 89Zr, we optimize the liquid–liquid-extraction process by means of the radiotracer technique. We produced 89Zr by proton irradiation of a metallic yttrium target at a cyclotron. The purification of the radionuclide was performed by a UTEVA resin. 89Zr was separated in no-carrier-added form in a sulfuric acid solution. 89Zr was successfully used in solvent extraction tests with calixarenes for the separation of zirconium from lanthanides. This reaction is suitable for the efficient extraction and purification of lanthanides.