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2 2009

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Radiation processing of detergents and possible environmental benefits

Borrely S. I., Romanelli M. F., Pereira M. C. C., da Silva G. P., Mesquita L. C. A., de Moraes M. C. F.

Nukleonika

2009

Vol. 54, No. 2

61-64

Detergents at waters inducing negative changes for biological degradability and water general quality. Some authors have evidenced a considerable amount of anionic surfactant and toxic effects into natural water and effluents related to detergents. The objective of the study was to apply electron irradiation for reducing toxicity, and for degradation of surfactants. To quantify surfactant LAS determination as MBAS (metylene blue active substances) was applied. The capacity of radiation to reduce surfactants was evidenced for real effluent and for water solution containing sodium dodecyl sulfate, linear alkylbenzene sulfonate (LAS), separately. An electron beam accelerator (EBA) 1.5 MeV was the radiation source. Anionic surfactant solutions as well as real effluents resulted in less toxic samples after irradiation. Toxicity was evaluated for Vibrio fischeri and Daphnia similis. An important decline of total anionic surfactant was observed after irradiation to doses: 6.0 kGy and 20 kGy (surfactant in water solutions and effluents, respectively). To conclude, EBA irradiations accounted for 88% to 96% less toxic surfactants solutions and effluents and 68% to 96% for MBAS compounds decomposition.

Development of crystals based on cesium iodide for measurements of gamma radiation and alpha particles

Pereira M. C. C., Filho T. M., Hamada M. M.

Nukleonika

2009

Vol. 54, No. 3

151-155

During the past 50 years, scintillators have been among the most important nuclear radiation detectors. Inorganic scintillators are widely used in experimental nuclear physics, high energy physics, nuclear medicine, nuclear tomography, environmental studies and many other fields of use. Scintillation crystals based on cesium iodide (CsI) are matters of relatively low hygroscopy, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, the growth of pure CsI crystals, CsI:Br and CsI:Pb, using the Bridgman technique, is described. Ions of divalent lead (Pb2+) doped in the crystal structures are efficient emission centers and their application as scintillators is still the reason for intensive studies. Recently, promising results have been found for crystals of CsI doped by bromine (Br) for their use as radiation detectors. The concentration of the bromine doping element (Br) was studied in the range from 1.5 × 10–1 M to 10–2 M and the lead (Pb) in the range from 10–2 M to 5 × 10–4 M. To evaluate the scintillators developed, systematic measurements were carried out for luminescence emission and luminescence decay time for gamma radiation, Vickers microhardness assays, and analysis of crystals response to the gamma radiation, in the energy range from 350 keV to 1330 keV, and alpha particles from a 241Am source, with energy of 5.54 MeV. The obtained values for luminescence decay time for CsI:Br and CsI:Pb crystals, were from 13 to 19 ns.