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Radiation degradation of waste waters
I. Reverse phase-high performance liquid chromatography and multicomponent UV-VIS analysis of gamma-irradiated aqueous solutions of nitrobenzene
Abstract
Saturated aqueous solutions of nitrobenzene (in water, 0.1M nitric acid and 0.1M potassium hydroxide) were irradiated with60Co 
-rays in deaerated condition. Radiolytic products were analyzed using reverse phase-high performance liquid chromatography (RP-HPLC) and multicomponent UV-VIS spectrometry. With the aid of RP-HPLC retention times of the radiolytic products were found to be identical with those of isomeric nitrophenols, aminophenols and dinitrophenols. According to the primary information obtained from RP-HPLC and literature, we have chosen ten standards and eleven wavelengths for multicomponent UV-VIS analysis (linear multiparametric regression analysis) and the concentrations of nitrobenzene, nitrophenols, aminophenols and dinitrophenols in water, HNO3 and KOH solutions were calculated.G-values molecules/100 eV) of the radiolytic products and decomposition of nitrobenzene in aqueous solutionsG(-nitrobenzene) were calculated from the dependence of their concentrations with dose. Ph has relatively little influence on the decrease of concentration of nitrobenzene, but has strong influence on the product composition.
Abstract
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.
Abstract
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.
Abstract
Capillary gas chromatography — Fourier transform infrared spectroscopy combined with capillary gas chromatography — mass spectrometry is employed for the analysis of major volatile products in the 
-radiolysis of isomeric nitrophenol solutions in carbon tetrachloride. Isomeric di- and trichlorophenols, chloronitrophenols and dichloroisocyanatobenzenes in addition to those formed with m- and p-isomers, are among the important products formed in the solution of o-nitrophenol in carbon tetrachloride. Formation of dichloroisocyanatobenzene is explained by the interaction of dichlorocarbene with the nitro group followed by the ipso-substitution of OH and H atom by chlorine atom.
Abstract
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.
Abstract
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 (T G(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.
Abstract
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.
Abstract
Radiolytic products of the two-phase systems of nitrobenzene-carbon tetrachloride-water mixtures have been identified using HPLC adsorption chromatography on SEPARON SIX silica gel column under an elution gradient from n-hexane to ethyl acetate. That the product formation is a function of the mixture composition is indicated by the chromatograms. Para-nitrophenol constitutes one of the major radiolytic products in the system where the volume ratio of nitrobenzene is more than that of carbon tetrachloride and its radiation yield is dependent on the volume ratio of the aqueous phase.
Abstract
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 (D
37), initial concentration (g·m–3) of phenol (p
0) and of an admixture (s
0) was confirmed in the formD
37=52f
tr(p
0+f
eq
s
0), wheref's are constants which can be attributed to the relative transformation resistance of phenol towards the OH radicals in given matrix (f
tr, for pure waterf
tr=1) and relative acceptor capacity of competing substrate (f
eq). 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.
