J. Kuruc

Gamma-radiolysis of some crown ethers and their analogues. Electron spin resonance specra of free radicals

The method of low temperature ESR spectroscopy was used to study the free radicals generated by γ-irradiation of crown ethers: 12-crown-4 /1/; 15-crown-5 /2/; dicyclohexane-24-crown-8 /3/; and their analogues: tetrahydrofurane /4/ and 1,4-dioxane /5/. ESR spectra of radicals 4 and 5 taken at 77 K represent a simple singlet; ESR spectra of radicals generated from 1, 2 and 3 have a complex, multiplet structure. The kinetics of thermal decay of free radicals 4 in dependence on temperature starting from 103 K was investigated. The radicals 4 decay very fast at 253 K.

Determination of radiolytic products of two-phase tributylphosphate—Water systems by capillary isotachophoresis

A capillary isotachophoresis was used for determination of ionogenic radiolytic products of two-phase tributylphosphate—water systems. Optimum operating conditions for analytical determination of dibutylphosphate (DPP), monobutylphosphate (MBP), H3PO4, formic, acetic, propionic and butyric acid were found.

Radiolysis of carbon tetrachloride-nitrobenzene mixtures. Radiation yields of major liquid products

The yields of major non-gaseous radiolytical products in the mixtures of carbon tetrachloride-nitrobenzene in a wide concentration scale have been established and found to depend on the composition of the mixture. Decrease of the yield hexachloroethane with increasing concentration of nitrobenzene was explained by the energy transfer from CCl4 to the molecule of C6H5NO2. Chlorobenzene is formed from an exciplex [CCl4.C6H5NO2]* or complex with charge transfer or from reaction of the excited molecules of nitrobenzene, and the formation of dichlorobenzenes, trichlorobenzenes and chloronitrobenzene can be explained by radical substitutional reactions.

Quantum yields of photosubstitution of the nitro group in nitrobenzene-tetrachloromethane mixtures

The quantum yield of nitrobenzene disappearance has been determined. The mechanism of the photosubstitution of nitro group by the photolysis of nitrobenzene-tetrachloromethane mixture is discused.

Spin trapping of free radicals generated by gammaradiolysis of crown ethers and their analogues

Gamma-radiolytically generated radicals of crown ethers /12-crown-4, 1; 15-crown-5, 2; dicyclohexano-24-crown-8, 3/ and the model compounds /tetrahydrofurane, 4 and 1,4-dioxane, 5/ were studied by the spin-trapping method using C-phenyl-N-methylnitrone /PBN/ as a spin-trapping agent giving rise to the sufficiently stable nitroxyl radicals. The spin adducts of radicals 2 and 3 are relatively stable up to the temperature 253 K and 453 K, respectively.

ESR spectra of radicals at a low-temperature X-radiolysis of phosphates

ESR spectroscopy at 77 K has been used for the investigation of radicals formed in the low-temperature X-radiolysis of tri-n-butylphosphate /TBP/, di-n-butylphosphate /DBP/, di /2-ethylhexyl/phosphoric acid /DEHPA/, tri-p-tolylphosphate /TTP/, di-n-butyl-n-butylphosphonate /DBBPN/. Besides the phosphate radicals also hydrogen atom stabilization in the matrix has been observed. In the presence of oxygen peroxy radicals occur as well. The structure of the radicals and reaction mechanisms are discussed.

The preparation of the 239Np tracer from 243Am and the purification of the stock solution

The present work describes preparation of 239Np tracer from 243Am stock solution and the purification of this solution from ferric cation. The method of the preparation of tracer involves stabilization of Np(IV) by ascorbic acid and ferric nitrate, separation of 239Np from 243Am by extraction chromatography and determination of recoveries of 239Np by means of gamma spectroscopy. We used the commercially available sorbents TEVA®Resin for the 239Np preparation and DGA Resin for 243Am purification. All sorbents were purchased from Eichrom Industries, Inc. The first eluate from the column can be stored for a future preparation of the tracer and fraction with 239Np will be used to monitor radiochemical yield of 237Np.

Determination of radiation yields of ionogenic products of two-phase water-dibutylphosphate systems by capillary isotachophoresis

The main ionogenic radiolytical degradation products are monobutylphosphate, phosphoric acid, formic, acetic, propionic and butyric acids as the result of gamma-irradiation of two-phase water-dibutylphosphate system. The products were determined using capillary isotachophoresis. According two-phase theory the total (TG(X)) and partial (GI(X) for aqueous phase and GII(X) for organic phase) radiation yields of products and decomposition of DBP in the radiolysis of two phase water-dibutylphosphate systems were calculated from the results.

Determination of radiation yields of ionogenic products of two-phase water-tributylphosphate and water-di-(2-ethylhexyl)-phosphoric acid systems by capillary isotachophoresis

It was found that the main ionogenic radiolytical degradation products of tributylphosphate were monobutylphosphate dibutylphosphate, phosphoric acid, formic, acetic, propionic and butyric acids as the result of gamma-irradiation of two-phase water-tributylphosphate system. In the case of irradiation of two-phase water-di(2-ethylhexyl)-phosphoric acid system, the main radiolytic degradation products are 2-ethylhexylphosphoric acid and phosphoric acid. All products were determined using isotachophoresis. According two-phase theory the total and partial radiation yields of products were calculated from the results.

RADIATION OXIDATION OF PHENOL IN THE PRESENCE OF PETROCHEMICAL WASTEWATER COMPONENTS

Radiolytical decomposition of phenol was investigated at60Co gamma irradiation (1–2 Gy·s−1, ≤10 kGy) of pre- and continuously aerated aqueous solutions at concentrations of phenol 1–100 mg· ·dm−3 and in the presence of sodium hydroxide, sulphuric acid, sodium and ferrous sulphate, formaldehyde, 2-propanol,n-hexane, xylene, benzene, and commercial gasoline. From the decomposition rate at doses 50–400 Gy, a phenomenological model of linear relation between the dose acquired for 37% decomposition (D37), initial concentration (g·m−3) of phenol (p0) and of an admixture (s0) was confirmed in the formD37=52ftr(p0+feqs0), wherefs are constants which can be attributed to the relative transformation resistance of phenol towards the OH radicals in given matrix (ftr, for pure waterftr=1) and relative acceptor capacity of competing substrate (feq). In real wastewaters, the efficient decrease of phenols content may be substantially lower than that in model solutions, obviously due to radiation oxidation of aromates, as proved by irradiation of aqueous solutions of benzene. Technical and economical feasibility of the process is discussed.