This article is focused on the effect of γ-induced radiation in in situ sorption measurements of60Co (emitting β-and γ-radiation). The results presented show that the intensity of solution background is primarily due to the γ-induced radiation (possibly caused by photoeffect and Compton-scattering) and does not change during cobalt accumulation. Experiments were carried out with a pure β-emitting isotope (99Tc) in order to elaborate a method for the separation of the intensities originating from β-and γ-induced radiations. Various methods of evaluation of sorption measurements are discussed. The extension of the method to application of different radioactive nuclides is considered.

Experiments on sorption of cobalt onto polyethylene foil from buffered borate solutions are reported in this paper. Sorption isotherms and sorption kinetics of cobalt as a function of pH and the effect of borate species on cobalt sorption were investigated. The results show that the extent of cobalt sorption is lower in borate buffer than in Na ClO4 solution. It is found that the adsorption isotherms obtained are dependent on the pH of the solution. Possible reasons of the influence of pH on the sorption isotherms are discussed.

A new approach for the characterization of coatings with respect to their corrosion protection is presented. The applicability of a simple in situ radiotracer method and some information which can be gained from sorption measurement of corrosive ions are demonstrated based on the results obtained in case of HSO4−/SO42− accumulation on a coating chosen. The technique used has low detection limit and the measurements can be performed without disturbing the primary experimental conditions.

The applicability of an in situ radiotracer method is described for the investigation of cobalt sorption. To follow the accumulation of60Co-labeled species on different surfaces, the β-radiation of60Co is measured. To demonstrate the usefulness of the method, some illustrative results gained from the measurement of cobalt sorption on polyethylene foil and glass powder are given. From the results it is obvious that this method has a low detection limit and high sensitivity even in case of low adsorbent surface areas.

The kinetics of chromate coating formation and chromium(VI) exchange has been studied by of novel continuous radiotracer method. Comparison has been made with former results obtained by a quasi-continuous procedure and kinetic constants have been determined.

An attempt is made to elaborate a versatile radiotracer method for the study of sorption phenomena at various sorbents (metal layers, powdered metal samples, protective coatings) using isotopes emitting β and/or γ radiation.

The composition of the passive layer on aluminium and reformation of this layer during cathodic polarization were investigated by radiotracer and electrochemical methods in the presence of sulphate and chloride ions. Chloride ion is not ab- or adsorbed on the passive layer but, attacks this layer as a chemical reaction partner. Therefore, the pitting corrosion of aluminium and its alloys is a combined electrochemical and chemical process. The cathodic reformation of passive layer is indicated by the changing of the concentration of bonded chloride ion, the changing of hydrogen overvoltage as well as the shift of Eπ potential.

As a continuation of previous studies [1] the adsorption of 35 S labelled H 2 SO 4 was studied on stainless steel in order to distinguish the adsorption of HSO t- 4 and SO t- 4 species. It was found that a clear distinction can be made between the adsorption of these two species at low H 2 SO 4 concentrations and relatively high pH values (pH > 6). Through a study of the competitive adsorption with H 3 BO 3 or H 2 BO t- 3 species it was possible to demonstrate the differences in the adsorption of HSO t- 4 and SO 2t- 4 species.

As a continuation of previous studies [1] the adsorption of35S labelled H2SO4 was studied on stainless steel in order to distinguish the adsorption of HSOt-4 and SOt-4 species.

Adsorption of SO2−4 (HSO−4) and Cl− ions on a powdered stainless steel (08X18H10T), used as constructional material in VVER nuclear reactors, was studied by a radiotracer method. The concentration, potential- and pH dependence of the adsorption was investigated. No significant adsorption of Cl− ions was observed. The observed pH dependence of H2SO4 adsorption allows us to assume that the adsorption is determined by the concentration of HSO−4 ions and a logarithmic adsorption isotherm with respect to these ions can be fitted to the experimental results.

Adsorption of SO 2− 4 (HSO − 4 ) and Cl − ions on a powdered stainless steel (08X18H10T), used as constructional material in VVER nuclear reactors, was studied by a radiotracer method. The concentration, potential- and pH dependence of the adsorption was investigated. No significant adsorption of Cl − ions was observed. The observed pH dependence of H 2 SO 4 adsorption allows us to assume that the adsorption is determined by the concentration of HSO − 4 ions and a logarithmic adsorption isotherm with respect to these ions can be fitted to the experimental results. Competitive adsorption of HSO − 4 ions with Cl − and CrO 2− 4 ions was studied and discussed.

The sorption behaviour of HSO−4 and Cl− ions on stainless steel is discussed in the light of recent theories of passivity attributing a significant role to the Cr content and the state of Cr species in the passive layer. It is shown through experimental evidences that a link between the formation of Cr3+ species in the passive film and HSO−4 sorption can be formulated.

The sorption of 36Cl labelled Cl− ions into the layer of corrosion products adhered to the surface of corroding powdered steel samples has been studied as a function of the time at 1.8 × 10−2 NaCl concentration. The effect of CrO2−4 and SO2−4 ions on the sorption process and the mobility of sorbed species was investigated.

Phosphate/chromate and accelerated chromate coatings were produced on commercially available aluminium. The Cr, P and Fe components of the conversion coatings were determined by radioactive tracer technique. The tracer technique was combined with ion-exchange and film-sectioning methods to determine the chromium (III)/total chromium ratio in the accelerated chromate coating. It was found that during the acidic dissolution of the conversion coating the chromium (III)/total chromium ratio may suffer changes. The filmforming components in the metal/bath interface are supersaturated and deposited onto the aluminium. The identified components of the accelerated chromate coatings are Cr/OH/3, Cr/OH/CrO4 and Cr4[Fe/CN/6]3 and the chromium (III)/total chromium ratio was found to be cca. 2/3.