Authors:Rafael de Pádua Ferreira, Solange Sakata, Fernando Dutra, Patricia Di Vitta, Maria Taddei, Maria Bellini, and Júlio Marumo
Waste management plays an important role in radioactive waste volume reduction as well as lowering disposal costs and minimizing
the environment-detrimental impact. The employment of biomass in the removal of heavy metals and radioisotopes has a significant
potential in liquid waste treatment. The aim of this study is to evaluate the radioactive waste treatment by using three different
bacterial communities (BL, BS, and SS) isolated from impacted areas, removing radioisotopes and organic compounds. The best
results were obtained in the BS and BL community, isolated from the soil and a lake of a uranium mine, respectively. BS community
was able to remove 92% of the uranium and degraded 80% of tributyl phosphate and 70% of the ethyl acetate in 20 days of experiments.
BL community removed 81% of the uranium and degraded nearly 60% of the TBP and 70% of the ethyl acetate. SS community collected
from the sediment of São Sebastião channel removed 76% of the uranium and 80% of the TBP and 70% of the ethyl acetate. Both
americium and cesium were removed by all communities. In addition, the BS community showed to be more resistant to radioactive
liquid waste than the other communities. These results indicated that the BS community is the most viable for the treatment
of large volumes of radioactive liquid organic waste.
The prepared amorphous
γ-ZrP\SiO2 composite had a complicated composition,
since a part of γ-ZrP is converted to α-form during the exfoliation
of it. The γ-ZrP\SiO2 composite have specific surface
area of 421 m2g–1.
The acidic P–OH groups of the lamellae species placed on the surface
(it is ≈1.0 meq g–1), do not destroy until
the temperature of 1030 K. During the thermal treatment the total mass loss
of 7.79% was found. This value corresponds to 0.42 mole of H2O
per molecule unit. The water loss process was found very slow, because of
the placing of bilamellar species in the composite.
Authors:P. Patrono, A. La Ginestra, C. Ferragina, M. A. Massucci, A. Frezza, and S. Vecchio
The Zr, Ti, Sn and Ge hydrogenphosphates, generally prepared in a crystalline form by the refluxing method, have been submitted to hydrothermal treatment at 180° and 300°C in order to observe if the preparation time can be shortened maintaining their chemical composition and their α-structure. Simultaneous TG and DTA together with XRD revealed to be very suitable techniques for the characterization of the obtained products.
Authors:E. Ordoñez-Regil, E. Romero Guzmán, and En. Regil
Natural fluorapatite samples were contacted with uranyl nitrate solutions (from 10−2 to 10−6M), adjusted to pH 6.0, then, shaken for times varying between 15 minutes to 72 hours, at room temperature. After that, the
solid and liquid phases were separated by centrifugation and the solid was dried at 80°C overnight. The uranium analysis of
the solid samples and solutions revealed that uranium was incorporated over fluorapatite. Selected solid samples produced
by contacting treatments were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. XRD patterns
showed the growth of uranyl species in the fluorapatite. Imaging by SEM at 20000x showed the location of uranyl compounds
in a crystalline layer in the surface of fluorapatite grains. This layer was well defined for the 10−2 M of U-contacting solution, but a saturation value was attained at 64% of uranium uptake yield. In the case of 10−4 M and lower U-contacting solution, the uranium uptake yield was near of 90% after 45 minutes. This fact suggests that natural
fluorapatite has excellent properties to immobilize uranium compounds in a solution. Afterwards, the pregnant fluorapatite
mineral was regenerated using an alkaline-leaching process. The uranium separated in this way is concentrated and can be handled
to a final disposition.
Authors:H. El-Didamony, M. Ali, N. Awwad, M. Fawzy, and M. Attallah
Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of harmful radioactive
materials. The reduction in concentration of the radionuclides from PG was investigated. The removal process is based on leaching
of radionuclides using suitable organic extractants. The studied radionuclides were 226Ra, 210Pb, 238U and 40K. The factors affect the leaching process such as type of leaching materials, contact time, concentration of the desired
solvent, liquid to solid ratio, and temperature were studied. Based on the experimental results, about 71.1, 76.4, 62.4, and
75.7% of 226Ra, 210Pb, 238U and 40K respectively were successfully removed from the PG. The reduction in the concentration of radionuclides was accompanied
by reduction in the concentration of rare earth elements (∑REE) equals to 69.8%. Using the desired organic extractant under
optimum conditions for treatment of the PG waste leads to obtain a decontaminated product that can be safely used in many
The photoluminescence (PL) of barite is a noncharacteristic property and cannot be used for the investigation of its structure.
After thermal treatment of barite at 600°C several luminescent centers were observed, providing information about different
was determined from the vibrational structure and the long decay time of the luminescence band. Two different types of uranyl
were detected, thin films of uranyl mineral (most probably, reserfordin) and a solid solution of uranyl ion in barite crystal.
Characteristic green luminescence of UO
may be used as indicative feature for the prospecting of uranium deposits and for the sorting of barite ores with the aim
of cleaning from harmful U impurities. Eu2+ was determined from the spectral position, the half-width and the characteristic decay time of the luminescence band.
Mn2+ and Ag+ were determined by comparing luminescence bands spectral parameters to those of synthesized BaSO4−Mn and BaSO4−Ag. Fe3+ or Mn4+ were determined from the spectral-kinetic parameters of the luminescence bands.
Authors:E. Hallaba, A. Al-Suhybani, S. Al-Khowaiter, and A. El-Sadik
Phosphate treatment of carbonaceous clays increased the uptake capacity for uranium and thorium. Heat treatment up to 400°C
improved enormously the uptake property of the treated clay. These treatments failed to improve the uptake quality of argileous
clays. Strontium exchanges weakly with clays of high Ca and Mg contents but strongly with a silicoaluminium clay of low Ca
and Mg contents. A mixed bed of these two clays was found adequate for decontamination of actinides and fission products.
The thermal behaviour of wool, untreated and chlorinated to various extents, was investigated. The kinetic parameters of the water loss and pyrolysis processes were computed and, based on their values, the way chlorination treatment affects wool fibre is discussed. As it appears, the chlorination process affects the fibre only superficially and not its internal chemical composition, as the values of the kinetic parameters of the thermal decomposition of wool fibre do not seem to be influenced at all by the treatment.
Authors:H. Oudadesse, A. C. Derrien, and M. Lefloch
In biomaterial field, the introduction of new types of composites presents a great interest for orthopaedic surgeons. In this work, geopolymers which are a family of aluminosilicates were synthesised and mixed with biphasic mixture (hydroxyapatite and of tricalcic phosphate). The optimised thermal treatment causes the reduction of pH to 7 units and favours the expansion of composites. Consequently, the increasing of porosity percentage was induced. These properties offer a good opportunity for applied composite as potential osseous biomaterial. To study the consequences of thermal treatment in the initial amorphous structure of composites some physico-chemical techniques like SEM, MAS-NMR and FTIR were employed. These methods permitted to evaluate the porosity, different links in composites and contributions of different groups of Si and Al before and after thermal treatment.