[en] Plumb shell was used to prepare an adsorbent for biosorption of lead ions in aqueous solution at 25 degree C. The adsorption capacity of the adsorbent at equilibrium was found to increase from 2.8 to 49.0 mg/g with an increase in the initial lead ion concentration from 50 to 200 mg/L. Using the equilibrium and kinetics studies, isotherm of the lead ions on the biosorbent was determined and correlated with common isotherm equations. The equilibrium data for lead ion adsorption fitted well into the Freundlich equation, with a value of 0.76 (R2 = 0.9), with distribution coefficient of 4.90. The biosorption of lead ions on the adsorbent from plumb shells could best be described by the pseudo-second-order equation. The kinetic parameters of this best-fit model were calculated and discussed. (author)

[en] Molybdenum is removed from a uranium bearing solution, including alkaline carbonate solutions, by adding a compound which provides lead ion to react with the molybdenum present to form insoluble lead molybdate (PbMoO₄) which precipitates from the solution

[en] The note reports on the effects of lead implantation on the corrosion and polarization behaviour of Fe. Pb was selected as an ion which was normally completely insoluble in Fe and was expected to modify the electrochemical behaviour markedly. The corrosion behaviour of Fe specimens implanted with two different doses of Pb was examined using a three sweep potentiokinetic polarization technique. In addition, the corrosion current was estimated. (U.K.)

[en] Lead ions are removed using liquid emulsion membrane (LEM) technique. Phase Inversion method is used to prepare liquid emulsion membrane that does not require high stirring compare to conventional method and gives equal results. The LEM consists of di-(2-ethylhexyl) phosphoric acid as a carrier, commercial kerosene as an organic solvent, Triton X-100 or house hold detergents as an emulsifying agent and sulphuric acid as stripping agent. To prepare a stable emulsion various factors are involved such as emulsification time, effect of volume ratio of oil phase to internal (stripping) phase, concentration of surfactant, carrier and internal phase which affect the final removal efficiency. Some other factors that affect removal efficiency such as contact time and volume ratio of emulsion to external (feed) phase are also studied. Due to high removal efficiency of this technique, 90 to 99% Lead is removed in 5 to 10 minutes at optimum conditions. (author)

[en] Sequential injection (SI) with bead injection (BI) and lab-on-valve (L-O-V) was exploited for determination of trace lead using electrothermal atomic absorption spectrometry (ETAAS). A renewable microcolumn incorporated within the L-O-V system was investigated by using Sephadex G-25 impregnated by dithizone. Lead solution was passed through the impregnated beads. The beads were directly propelled into a graphite tube where they were pyrolyzed and lead ions were subsequently atomized. Conditions of the ETAAS measurement were studied including chemical modifiers (palladium, molybdenum and tartaric acid). The SI system for trapping of lead on the beads in the L-O-V could be operated in parallel to the ETAAS operation

[en] The present study was undertaken to examine the influence of such chelating agents on the ease and speed of photocatalyzed metal removal and deposition. With excess EDTA, the free EDTA competes with Pb for oxidation, and at a ten fold excess, no lead oxidation (hence removal) occurs. With insufficient EDTA, the corresponding initial concentration of Pb-EDTA is decreased; after its destruction, the remaining Pb²⁺ is removed more slowly, at rates found with lead nitrate solution. The net result is that the maximum rate of lead deposition occurs at the stoichiometric ratio of 1:1 EDTA : Pb²⁺

[en] Aqueous pollutants of cesium, iodide, lead, zinc and chromate ions adsorbed on natural and Ag⁺(Pb²⁺) - or NH₄⁺- exchanged clinoptilolite together with surfactant hydrophobized, Ca-alginate pelletized as well as MnOx - and FeO(OH) - clinoptilolites compared with the inland montmorillonite were assessed. The investigations of zeolites (clinoptilolite type) for the removal of various kinds of aqueous pollutants incl. radioactive ones lead to the conclusion that this natural resource can be considered for an alternative cost-effective adsorption material, either with or without surface treatment, depending on the type of water to be purified. (author)

[en] A method to determine lead ion in aqueous media using an optical sensor loaded on a fluorescent optode membrane incorporating a metal ion-selective ionophore, a proton-selective chromoionophore and lipophilic anionic sites has been studied. The effects of pH and thickness of membrane on the fluorescence intensity were investigated. The effects of foreign ions such as Na⁺, K⁺, Mn²⁺ and Zn²⁺ on the determination of lead ion were also studied. The linear range in the calibration curve for the determination of lead ion was found to be 5.0x10^-7 to 5.0x10^-3 M and the correlation coefficient in this range was -0.99107 under the optimal experimental conditions. The relative standard deviation of the blank signals was 3.0% and the detection limit of lead ion was 5.0x10^-9 M

[en] The corrosion behavior of pure iron implanted with Pd ions up to doses in the range 1x10¹⁶-1x10¹⁸ ions/cm² at an extracting voltage 45kV by using MEVVA source ion implanter has been investigated. The concentration profiles and valence states of elements at the near surface of Pd implanted iron specimens were analyzed by AES and XPS respectively. The Anodic dissolution process of Pd implanted pure iron was measured by means of potentiokinetic sweep in a 0.5 mol/1 NaAc/Hac buffer solution with pH5.0. The open circuit corrosion potential as a function of immersion time was used to evaluate the corrosion resistance of Pd implanted iron specimens. The experimental results show that Pd ion implantation decreases the critical passive current of iron and maintains a better passivity in acetate buffer solution with pH5.0. It is interesting that the active corrosion rate of Pd implanted iron is even higher than that of unimplanted one, when the oxide layer on the surface of iron has been damaged. (author)

[en] A compact ion microbeam system, which comprises a three-stage acceleration lens and a duoplasmatron-type ion source and produces beam of several hundred kiloelectron-volts, has been developed to form a beam that has a diameter of several micrometers. Previous studies have indicated that a small divergence angle of an incident beam is required to improve the demagnification of the three-stage acceleration lens. A simulation of an ion beam extraction demonstrated that the optimum distance between the anode and the extraction electrode in the ion source could lead to an ion beam being generated with the smallest possible divergence angle. As a result, a hydrogen beam with a 2.6 μm diameter was experimentally produced at 120 keV.