Radiation treatment with gamma-rays was used to improve the biodegradability of EDTA that is known to be a non-biodegradable
substance. The effect of metal ions and catalysts on the treatment of EDTA was studied first. The removal of EDTA was definitely
decreased in the presence of metal ions such as Cr(III), Cd(II), Pb(II) and Cu(II) at doses greater than 3 kGy. The addition
of a TiO2
The possibility of applying chemical treatment prior to evaporation was discussed in the present work. Using titanium hydroxide-cobalt
ferrocyanide as coprecipitants allows fixation of high percentage of radioactive nuclides present (e.g. Cs 98%, Ru 90%, Sb
95%, Ce 98%, Am 95% and Pu 95%). Hence using such simple chemical separation before evaporation improves the process and leads
to several advantages, e.g. raising the decontamination factor, reducing radioactive aerosol production and solving the problem
of medium active waste treatment by adding the chemically precipitated solids to the high-active waste and the supernatant
to the low-active waste, are examples for these advantages.
Authors:H. J. Jo, S. M. Lee, H. J. Kim, J. G. Kim, J. S. Choi, Y. K. Park, and J. Jung
In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation
on biodegradability (BOD5/COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment
based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable
and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters,
gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such
as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This
may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp
wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However,
the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed
dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds
such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents.
Authors:J. L. Pérez-Rodríguez, F. Franco, V. Ramírez-Valle, and L. A. Pérez-Maqueda
The differences on the thermal behaviour (DTG-DTA) of antigorite sample measured before and after sonication have been studied.
Sonication treatment produces negligible changes in the structure of the material but substantial textural modifications.
These modifications produce changes in the thermal behaviour of antigorite sample. Thus, it has been observed a decrease in
the dehydroxylation temperature as measured by DTG and DTA effects. For sonication treatments longer than 20 h, two new effects
of dehydroxylation are observed, the intensity of these two new effects increases with the sonication time showing a modification
in the release of structural OH. It has been also observed that the formation of forsterite takes place simultaneously with
the dehydroxylation of the antigorite. The high temperature exothermic effect is due to the recrystallization of forsterite
and not to the formation of forsterite as traditionally assumed. Modifications in the thermal dehydroxylation of antigorite
observed in this study are related to the pronounced decrease in particle size obtained by sonication.
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.