Radon and progeny alpha-particle energy analysis using nuclear track methodology

Extraction of microamounts of cesium by nitrobenzene solutions of sodium, ammonium and thallium dicarbollylcobaltates (M⁺B⁻; M⁺ = Na⁺, NH₄⁺, Tl⁺) in the presence of benzo-15-crown-5 (B15C5, L) has been investigated. The equilibrium data have been explained assuming that the complexes ML⁺ and ML₂⁺ (M⁺ = Na⁺, NH₄⁺, Tl⁺; L = B15C5) are present in the organic phase. The stability constants of the complex species ML⁺ and ML₂⁺ in nitrobenzene saturated with water have been determined.     

Extraction of cesium into nitrobenzene by using ammonium and thallium dicarbollylcobaltates in the presence of polypropylene glycol PPG 425

Extraction of microamounts of cesium by nitrobenzene solutions of ammonium dicarbollylcobaltate (NH₄ ⁺B^?) and thallium dicarbollylcobaltate (Tl⁺B^?) in the presence of polypropylene glycol PPG 425 (L) has been investigated. The equilibrium data have been explained assuming that the complexes ML⁺ (M⁺ = NH ₄ ⁺ , TI⁺, Cs⁺; L = PPG 425) are present in the organic phase. Furthermore, the stability constants of the cationic complex species NH₄L⁺ and TlL⁺ in nitrobenzene saturated with water have been determined as log β (NH₄L _org ⁺ ) = 4.58 and log β (TlL _org ⁺ ) = 5.27.     

Extraction of microamounts of yttrium from water into nitrobenzene using hydrogen dicarbollylcobaltate in the presence of 15-crown-5

Summary Extraction of microamounts of yttrium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of 15-crown-5 (15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL_2,⁺, YL³⁺, YL_2,³⁺and YH_-1L_2,²⁺are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Stability of the ammonium-p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide) complex in nitrobenzene saturated with water

Summary From extraction experiments andg-activity measurements, the extraction constant corresponding to the equilibrium NH(aq)+NaL⁺(nb)?NH₄L⁺(nb)+Na⁺(aq) taking place in the two-phase water-nitrobenzene system (L = p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide); aq = aqueous phase, nb = nitrobenzene phase) was evaluated as logK_ex(NH,NaL⁺)=-1.8. Further, the stability constant of the p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide)-ammonium complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: logb_nb(NH₄L⁺)=6.7.     

Stability of Complexes of NH4 + with 18-Crown-6, Dicyclohexyl-18-Crown-6, Dibenzo-18-Crown-6 and Dibenzo-24-Crown-8 in Water Saturated Nitrobenzene

From extraction experiments with ²²Na tracer, the exchange extraction constants corresponding to the NH₄ ⁺(aq) + NaL⁺ (nb)NH₄L⁺(nb) + Na⁺ (aq) equilibrium taking place in the two-phase water-nitrobenzene system (L = 18-crown-6, dicyclohexyl-18-crown-6, dibenzo-18-crown-6 and dibenzo-24-crown-8; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the NH₄L⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the order dibenzo-24-crown-8 (DB24C8) < dibenzo-18-crown-6 (DB18C6) < dicyclohexyl-18-crown-6 (DCH18C6) < 18-crown-6 (18C6).     

Determination of microamounts strontium by substoichiometric isotope dilution analysis

The isotope dilution with substoichiometric separation for the determination of strontium has been investigated. Strontium can be extracted with a substoichiometric amount of bis-1,2-dicarbollylcobaltate in nitrobenzene in the presence of 15-crown-5. It has been found, that Li⁺, Mg²⁺, Ca²⁺ and Fe³⁺ do not interfere in the strontium determination but the high extraction of K⁺, Na⁺ and NH₄ ⁺ ions results in marked influence.     

Extraction of cesium by a nitrobenzene solution of sodium bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

The extraction of microamounts of cesium by a nitrobenzene solution of sodium bis-1,2-dicarbollylcobaltate (Na⁺B⁻) in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data have been explained assuming the complexes NaL⁺, NaL₂ ⁺, CsL⁺ and CsL₂ ⁺ to be extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Extraction of cesium by the nitrobenzene solution of hydrogen bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

Extraction of microamounts of cesium by the nitrobenzene solution of H⁺ bis-1,2-dicarbollylcobaltate (H⁺B⁻) in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data have been explained assuming the complexes HL⁺, HL₂ ⁺, CsL⁺ and CsL₂ ⁺ to be extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Extraction of barium by using nitrobenzene solution of cesium dicarbollylcobaltate in the presence of 15-crown-5

Extraction of microamounts of barium by a nitrobenzene solution of cesium dicarbollylcobaltate (Cs⁺B^-) in the presence of 15-crown-5 (15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes CsL⁺, CsL₂ ⁺ and BaL₂ ²⁺ are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Extraction of microamounts of strontium by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

Extraction of⁸⁵Sr by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data and the typical maxima concerning the dependencies of the Sr distribution ratios on the analytical concentration of 15C5 in the system under study can be explained assuming that the HL⁺, HL₂ ⁺ and SrL₂ ²⁺ species are extracted into the nitrobenzene phase. The values of the corresponding extraction and stability constants of the extracted species in nitrobenzene saturated with water have been determined.     

Extraction of barium by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

Extraction of barium by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data and the typical maxima concerning the dependencies of the Ba distribution ratios on the analytical concentration of 15C5 in the system under study can be explained assuming that the particles HL⁺, HL₂ ⁺ and BaL₂ ²⁺ are extracted into the nitrobenzene phase. The values of the corresponding extraction and stability constants of the extracted species in nitrobenzene saturated with water have been determined.     

Extraction of calcium by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

Extraction of calcium by a nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data and the typical maxima concerning the dependence of the Ca distribution ratios on the analytical concentration of 15C5 in the system under study can be explained assuming that the HL⁺, HL₂ ⁺ and CaL²⁺, CaL₂ ²⁺ particles are extracted into the nitrobenzene phase. The values of the corresponding extraction and stability constants of the extracted species in nitrobenzene saturated with water have been determined and the mutual Sr/Ca separation has been discussed     

Extraction of microamounts of calcium and strontium into nitrobenzene using synergistic mixture of hydrogen dicarbollylcobaltate and 2,3-naphtho-15-crown-5

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻) in the presence of 2,3-naphtho-15-crown-5 (N15C5, L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL₂ ⁺, CaL²⁺, CaL₂ ²⁺ and SrL₂ ²⁺ are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that in water saturated nitrobenzene the stability constant of the SrL₂ ²⁺ cationic complex species is substantially higher than that of the complex CaL₂ ²⁺.     

Solvent extraction of microamounts of cesium into nitrobenzene by using potassium and rubidium dicarbollylcobaltates in the presence of benzo-15-crown-5

Extraction of microamounts of cesium by nitrobenzene solutions of potassium dicarbollylcobaltate (K⁺B⁻) and rubidium dicarbollylcobaltate (Rb⁺B⁻) in the presence of benzo-15-crown-5 (B15C5, L) has been investigated. The equilibrium data have been explained assuming that the complexes ML⁺ and ML₂⁺ (M⁺ = K⁺, Rb⁺, Cs⁺) are present in the organic phase. The stability constants of the species ML⁺ and ML₂⁺ (M⁺ = K⁺, Rb⁺) in nitrobenzene saturated with water have been determined.     

Solvent extraction of microamounts of strontium from water into nitrobenzene by using cesium dicarbollylcobaltate in the presence of 15-crown-5

Extraction distribution of microamounts of strontium in the water-CsCl-15-crown-5 (15C5,L)-nitrobenzene-cesium dicarbollylcobaltate system has been investigated. The equilibrium data have been explained assuming that the CsL⁺, CsL₂ ⁺ and SrL₂ ²⁺ complexes are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Solvent extraction of microamounts of yttrium from water into nitrobenzene by using hydrogen dicarbollylcobaltate in the presence of benzo-15-crown-5

Summary Extraction of microamounts of yttrium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of benzo-15-crown-5 (B15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL, YL³⁺, YL and YH_-1L are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Solvent extraction of cesium into nitrobenzene by using hydrogen dicarbollylcobaltate and dodecaethylene glycol

Solvent extraction of microamounts of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻) in the presence of dodecaethylene glycol (DDEG, L) has been investigated. The equilibrium data have been explained assuming that the species HL⁺, H₂L²⁺, CsL⁺ and CsHL²⁺ (L = DDEG) are extracted into the organic phase. The values of extraction and stability constants of the complex species in nitrobenzene saturated with water have been determined.     

Extraction of cesium by the nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of dibenzo-18-crown-6

Extraction of cesium by the nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of dibenzo-18-crown-6 (DB18C6, L) was investigated. It was found, that besides hydrated cesium ion Cs _org ⁺ the complexes CsL _org ⁺ and CsL _2,org ⁺ were extracted to nitrobenzene phase. No maximums on dependencies of the cesium distribution ratio (D) on the concentration of crown in the systemc _L was found andD increased monotony withc _L. Values of extraction constants and stability constants of extracted species in nitrobenzene have been determined.     

Use of ICP and XAS to determine the enhancement of gold phytoextraction by <Emphasis Type="Italic">Chilopsis linearis</Emphasis> using thiocyanate as a complexing agent

Under natural conditions gold has low solubility that reduces its bioavailability, a critical factor for phytoextraction. Researchers have found that phytoextraction can be improved by using synthetic chelating agents. Preliminary studies have shown that desert willow (Chilopsis linearis), a common inhabitant of the Chihuahuan Desert, is able to extract gold from a gold-enriched medium. The objective of the present study was to determine the ability of thiocyanate to enhance the gold-uptake capacity of C. linearis. Seedlings of this plant were exposed to the following hydroponics treatment: (1) 5 mg Au L^–1 (2.5×10^–5 mol L^–1), (2) 5 mg Au L^–1+10^–5 mol L^–1 NH₄SCN, (3) 5 mg Au L^–1+5×10^–5 mol L^–1 NH₄SCN, and (4) 5 mg Au L^–1+10^–4 mol L^–1 NH₄SCN. Each treatment had its respective control. After 2 weeks we determined the effect of the treatment on plant growth and gold content by inductively coupled plasma–optical emission spectroscopy (ICP–OES). No signs of shoot-growth inhibition were observed at any NH₄SCN treatment level. The ICP–OES analysis showed that addition of 10^–4 mol L^–1 NH₄SCN increased the concentration of gold by about 595, 396, and 467% in roots, stems, and leaves, respectively. X-ray absorption spectroscopy (XAS) studies showed that the oxidation state of gold was Au(0) and that gold nanoparticles were formed inside the plants.     

Reduction of iodine by hydroxylamine within the pH range 0.7–3.5

The reduction of iodine by hydroxylamine within the [H⁺] range 3×10⁻¹–3×10⁻⁴ mol.L⁻¹ was first studied until completion of the reaction. In most cases, the concentration of iodine decreased monotonically. However, within a narrow range of reagent concentrations ([NH₃OH⁺]₀/[I₂]₀ ratio below 15, [H⁺] around 0.1 mol.L⁻¹, and ionic strength around 0.1 mol.L⁻¹), the [I₂] and [I₃⁻] vs. time curves showed 2 and 3 extrema, respectively. This peculiar phenomenon is discussed using a 4 reaction scheme (I₂+I⁻⇔︁I₃⁻, 2 I₂+NH₃OH⁺+H₂O→HNO₂+4 I⁻+5 H⁺, NH₃OH⁺+HNO₂→N₂O+2 H₂O+H⁺, and 2 HNO₂+2 I⁻+2 H⁺→2 NO+I₂+2 H₂O). In a flow reactor, sustained oscillations in redox potential were recorded with an extremely long period (around 24 h). The kinetics of the reaction was then investigated in the starting conditions. The proposed rate equation points out a reinforcement of the inhibition by hydrogen ions when [H⁺] is above 4×10⁻² mol.L⁻¹ at 25°C. A mechanism based on ion-transfer reactions is postulated. It involves both NH₂OH and NH₃OH⁺ as the reducing reactive species. The additional rate suppression by H⁺ at low pH would be connected to the existence of H₂OI⁺ in the reactive medium. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 785–797, 1998