A method has been developed using thermoanalytical techniques for the analysis of residues from coal-burning fluidised bed
plant where limestone is used as a sulphur scavenger. This completely eliminates the need for lengthy wet chemical analyses
and allows the derivation of parameters necessary for efficient plant operation, such as limestone addition rate, calcium
utilisation efficiency and calcium to sulphur mole ratio. The method also gives values for the unburned carbon content and
the ratio of coal ash to limestone derivatives in the sample.
Authors:P. Drzewicz, P. Pańta, W. Gluszewski, and M. Trojanowicz
The effect of pH of irradiated aerated solutions and the presence of various concentrations of bicarbonate and nitrate on
radiolytic degradation of 2,4-dichlorophenol in aqueous solutions with γ-irradiation was examined using reversed phase HPLC
and ion chromatography. The obtaining complete decomposition and dehalogenation of 2,4-dichlorophenol in the presence of naturally
occurring inorganic scavengers may require to increase the irradiation dose in batch conditions up to 10 kGy. The presence
of scavengers at different doses affects both efficiency of radiolytic degradation and its mechanism.
Behavior of cadmium(II) in aqueous solutions irradiated by accelerated electrons was studied. A concentration of 8.8 × 10−4 mol L−1 of cadmium dissolved from Cd(NO3)2 requires dose of 15 kGy to be effectively removed from the system containing 1 × 10−2 mol L−1 of HCOOK as a scavenger of OH radicals. The positive effect of deaeration with N2O or N2 was observed in the range of lower doses. The addition of solid modifiers (bentonite, active carbon, zeolite, Cu2O, NiO, TiO2 and CuO) reduced the effectivity of radiation removal of cadmium. Product of irradiation is CdCO3. On the contrary, in the system with cadmium dissolved from CdCl2 radiation reduction takes place. Systems contained organic complexants (ethylene diamine tetraacetic acid–EDTA, citric acid)
were also studied. The solutions of Cd(NO3)2 containing initial concentration 2.37 × 10−4 mol L−1 of CdII were mixed with 3 × 10−4 mol L−1 EDTA. In this system the efficient degradation proceeds up to 90% at a dose of 45 kGy with addition of 5 × 10−3 mol L−1 carbonate (pH 10.5). The product of irradiation is CdCO3. The presence of 1 × 10−2 mol L−1 of HCOOK in the solution is necessary for radiation removal of cadmium complexed with citric acid (1 × 10−3 mol L−1) at pH 8. With increasing concentration of HCOOK (up to 5 × 10−2 mol L−1) decreases the pH value necessary for the radiation induced precipitation of cadmium. The best result was obtained in the
system containing zeolite as a solid modifier.
Reactions of recoil38Cl atoms with CCl4 and C6H5Cl have been studied in presence of various high electron density scavengers. Relative reactivities of recoil38Cl towards the two components of these mixtures are determined using the model proposed by Urch.
Authors:S. Husaini, J. Zaidi, Matiullah, and M. Akram
The industrial pollution is exponentially growing in the developing countries due to the discharge of untreated effluents
from the industries in the open atmosphere. This may cause severe health hazards in the general public. To reduce this effect,
it is essential to remove the toxic and heavy metals from the effluents before their disposal into the biosphere. In this
context, samples of the effluents were collected from the textile/yarn, ceramics and pulp/paper industries and the concentrations
of the toxic metal ions were determined using neutron activation analysis (NAA) technique. The observed concentration values
of the As, Cr and Fe ions, in the unprocessed industrial effluents, were 4.91 ± 0.8, 9.67 ± 0.7 and 9.71 ± 0.8 mg/L, respectively
which was well above the standard recommended limits (i.e. 1.0, 1.0 and 2.0 mg/L, respectively). In order to remove the toxic metal ions from the effluents, the samples were treated with pea nut husk fence.
After this treatment, 91.5% arsenic, 81.9% chromium and 66.5% iron metal ions were successfully removed from the effluents.
Then the treated effluents contained concerned toxic metal ions concentrations within the permissible limits as recommended
by the national environmental quality standards (NEQS).
The kinetics of decay of trapped electrons via tunnelling to acceptor molecules in a glassy matrix was computed by the method of stochastic simulation. The kinetic curves of electron decay were obtained for different concentrations of electron acceptor in the matrix. The results of the simulation are compared with the corresponding results calculated on the basis of certain kinetic models of the electron tunnelling in low-temperature glasses.
Authors:M. Nakayama, R. Fujiyoshi, and S. Sawamura
Uptake of manganese(II) and zinc(II) by chlorophylla (Chl) was investigated using a radiotracer technique in order to elucidate
its ability of scavenging metals released into the soil environment. Two possibilities were considered for the metal uptake:
(1) substitutional complexation with Chl and (2) inclusion of the metals into Chl aggregates. It was found that manganese(II)
was not trapped appreciably by both Chl itself and its aggregates. Magnesium of Chl was exchanged with zinc(II) in aqueous
phase giving Zn−Chl at pH values higher than 7. Zinc(II) was found to be trapped by Chl aggregates depending on the pH of
the aqueous phase.
Authors:Y. Ito, Hamdy Mohamed, V. Byakov, and S. Stepanov
Positronium formation experiments inn-hexane were performed with C2H5Br and CCl4 as inhibitors and others (decalin, tetralin, benzene, naphthalene, phenanthrene) as anti-inhibitors. Although the results can be interpreted in terms of the anti-recombination and anti-inhibition, it is necessary to consider further some new aspects of intra-spur reactions such as shallow tapping of e+ and secondary reactions of Ps. The data thus interpreted correlate excellently with the data of radiation chemistry.
Authors:Łukasz Cieśla, Jakub Kryszeń, Anna Stochmal, Wiesław Oleszek, and Monika Waksmundzka-Hajnos
The aim of the presented study was to develop a simple, high-throughput analytical procedure to indicate volatile samples (essential oils and natural aromas commonly used in pharmaceutical and food industry), as well as individual compounds/group of compounds possessing free radical scavenging and/or acetylcholinesterase (AChE) inhibitory activity (one or both of the aforementioned properties). First, simple “dot-blot” tests were proposed to pinpoint the samples with the aforementioned activities. Some of those which gave positive results were passed to further analyses by means of low-temperature thin-layer chromatography (TLC). The comparison of the results obtained on different adsorbents led to a conclusion that TLC-AChE inhibition diazotization test should be performed on plates with polar coatings. The hypothesis for the observed weak AChE inhibitory activity on RP-18W plates, when compared to other adsorbents, is also proposed for further verification. The application of these procedures revealed that essential oils obtained from Rosmarinus officinalis, Lavandula officinalis, and Melissa officinalis contain substances with both direct antioxidant and AChE inhibitory activities.