In gamma irradiated aqueous acidic uranium solutions, tetravalent uranium ions are easily oxidized while U(VI) ions remain unchanged. In general, valence change of polyvalent metallic ions during chemical reprocessing...In gamma irradiated aqueous acidic uranium solutions, tetravalent uranium ions are easily oxidized while U(VI) ions remain unchanged. In general, valence change of polyvalent metallic ions during chemical reprocessing of spent nuclear fuel solutions can lead to undesirable effects under the influence of the existing gamma radiations. Consequently, studies on valence stabilization of Uranium ions during chemical treatment in strong gamma irradiation fields seem to be highly interesting. It has been reported before that some organic compounds proved to be effective in stabilizing the valence of Fe(II) ions during extended gamma irradiation of their acidic solutions. In the present work, valence stabilization of Uranium ions in acidic solutions in presence of different classes of organic compounds has been studied. The results showed that in case of U(IV), methanol or formic acid are capable of providing about 80% protection while ethanol or acetaldehyde can provide about 70% protection. Propanol has the least protective effect i.e. about 54%. On using U(VI) instead of U(IV) in the irradiated solutions, the uranium ions were reduced and the formed U(IV) was protected as follows: formic acid or methanol can provide 69% or 63% protection respectively while ethanol, acetaldehyde or propanol can provide 50%, 35% and 24% respectively. In any case, protection exists as long as the organic additives were not completely consumed.展开更多
Aging of ancient raw materials usually finish with disintegration, which starts on surface of walls to progress toward the inside mass of a huge variety of mineral compounds. This is particularly harmful when antique ...Aging of ancient raw materials usually finish with disintegration, which starts on surface of walls to progress toward the inside mass of a huge variety of mineral compounds. This is particularly harmful when antique buildings keep mural paintings, which suffers destruction before the wall itself. Same case appears on sculptures and monuments, whose surfaces are often attacked by living organisms which start a deterioration process previous to complete disintegration. The main factor to produce these unwanted effects is humidity, either rain for materials exposed to open air, or underground humidity going up by capillarity of minerals, in this case represented by porosity of associated salts forming the material. This paper describes a method to measure easily the relative porosity of diverse raw materials at laboratory level, by using a radioactive labeled solution, and also a procedure to reduce their porosity of those minerals. The efficiency of this procedure is measured in the same way, and so the results obtained at laboratory level have encouraged its use at real scale, where it has been quite successful for a number of materials in a limited span of five years.展开更多
Using 43 documented drill core samples of the H_5-chondrite 'Jilin' the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the seco...Using 43 documented drill core samples of the H_5-chondrite 'Jilin' the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the second (4π-) irradiation stage of 'Jilin'. Relics of the track record of the first (2π-) exposure are indicated by a deviation from the theoretical depth profile of the 4π-exposure. No Pu-244 fission is observed ia the fission track background near the meteorite center. The atmospheric ablation thickness of the two drill cores A and B normal and parallel to the assumed surface of the 'Jilin' parent body was found to be 11±4 cm, respectively. A minimum shielding depth of the 'top' part of core A during the 2π-exposure is estimated to be～30 cm. Near surface deviations of the experimental track data from theory are ascribed to a short-term moderate heating event (equivalent to 24h,～370℃) no more than 0.4 Ma ago. The resulting partial track annealing in a surface layer of ～15—20 cm thickness of the preatmospheric body can explain the lack of GCR-tracks in Jilin samples from very shallow depths that are based on ^(60)Co measurements.展开更多
The current industrial-scale production of molybdenum-99(^(99)Mo)and iodine-131(^(131)I)is heavily predicated on thermal neutron irradiation of LEU targets.In this route,^(99)Mo and ^(131)I are separated using a solid...The current industrial-scale production of molybdenum-99(^(99)Mo)and iodine-131(^(131)I)is heavily predicated on thermal neutron irradiation of LEU targets.In this route,^(99)Mo and ^(131)I are separated using a solid-phase extraction approach.The goal of this study was to develop and evaluate copolymeric beads that could be used to separate ^(99)Mo and ^(131)I from their aqueous solutions.Different aminated styrenedivinyl benzene co-polymeric beads were successfully manufactured for this approach.The structural features of the synthesized copolymers were characterized.The resin frameworks were found to have homogeneous spherical shapes decorated with a very thin layer of amine moieties.The FT-IR peaks caused by N—H stretching and C—N bending vibrations show the successful functionalization of the resins'surfaces with amine moieties selective for the sorption of I-over Mo O_(4)^(2-)ions.Under various circumstances,the produced resins were assessed for sorption of ^(99)Mo and ^(131)I from their aqueous solutions.They showed an enhanced sorption capability for I-ions compared to MoO_(4)^(2-)ions and attained equilibrium in less than 20 min.Data declare that the sorption of MoO_(4)^(2-)and I-ions onto synthesized resins was attained through an ion exchange process with Cl-ions.In such interactions,one iodide ion(I-)consumes only one active site from the resin surface,while two active sites must be exhausted to retain one MoO_(4)^(2-)ion onto the surface of the resins.The exchange interaction of both MoO_(4)^(2-)and I-ions was an endothermic process.Further,the elution of ^(99)Mo and ^(131)I radioisotopes loaded on synthesized resins was investigated using various eluents.Additional sets of individual and binary dynamic experiments were performed using columns packed with trimethylamine styrene divinyl benzene(TMA-PSDVB)and triethylamine styrene divinyl benzene(TEA-PSDVB)resins.The individual breakthrough sorption capacity of TMA-PSDVB and TEA-PSDVB resins had values of 381.6 and352.6 mg·g^(-1)for ^(131)I and values of 134.7 and 117.2 mg·g^(-1)for ^(99)Mo isotopes,respectively.Furthermore,TMA-PSDVB resin exhibited breakthrough sorption capacity for ^(99)Mo and ^(131)I,in the binary system,amounting to 123.7 and 331.6 mg·g^(-1)with elution percentages reaching 75.4%and 12.1%,respectively.These findings demonstrate that Mo(Ⅵ)ions were efficiently separated from I(Ⅰ)ions.Finally,the reported aminated polymeric resins may be regarded as promising solid phases for the separation and recovery of Mo(Ⅵ)and I(Ⅰ).展开更多
Metal-substituted cobalt ferrites [MxCo(1-x)Fe2O4(M=Zn,Cu,Mn;x=0.0,0.25,0.5,and 0.75)]were synthesized via a sol-gel technique.The ferrite structures were confirmed by X-ray diffraction, Fourier transform infrared spe...Metal-substituted cobalt ferrites [MxCo(1-x)Fe2O4(M=Zn,Cu,Mn;x=0.0,0.25,0.5,and 0.75)]were synthesized via a sol-gel technique.The ferrite structures were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy,scanning electron microscopy,surface analysis using the Brunauer-Emmett-Teller method,and energy-dispersive X-ray spectroscopy.Antimicrobial activity of these ferrites against selected pathogenic microbes was determined.The structures remained cubic spinel phases after substitution of metals.Substitution strongly influenced the microstructure and homoge- neous grain distribution.The particle size of the ferrites increased linearly with increase in their annealing temperature.The surface area of zinc cobalt ferrite nanoparticles (ZCFO)was 52.56m^2/g,the average pore size was 1.84nm,and pore volume was 0.136mL/g.All ferrites showed antimicrobial activity toward all pathogens selected.Of these,the most powerful was ZCFO,showing zones of inhibition of 13.0mm against Bacillus subtilis and Staphylococcus aureus and 12.0mm against Candida albicans.Gamma-irradiated ZCFO nanoparticles (150.0kGy)maintained higher antimicrobial activity than non-irradiated particles,e.g. being active toward S.aureus (16.0mm).ZCFO is proposed as a candidate material for industrial and biomedical purposes.展开更多
文摘In gamma irradiated aqueous acidic uranium solutions, tetravalent uranium ions are easily oxidized while U(VI) ions remain unchanged. In general, valence change of polyvalent metallic ions during chemical reprocessing of spent nuclear fuel solutions can lead to undesirable effects under the influence of the existing gamma radiations. Consequently, studies on valence stabilization of Uranium ions during chemical treatment in strong gamma irradiation fields seem to be highly interesting. It has been reported before that some organic compounds proved to be effective in stabilizing the valence of Fe(II) ions during extended gamma irradiation of their acidic solutions. In the present work, valence stabilization of Uranium ions in acidic solutions in presence of different classes of organic compounds has been studied. The results showed that in case of U(IV), methanol or formic acid are capable of providing about 80% protection while ethanol or acetaldehyde can provide about 70% protection. Propanol has the least protective effect i.e. about 54%. On using U(VI) instead of U(IV) in the irradiated solutions, the uranium ions were reduced and the formed U(IV) was protected as follows: formic acid or methanol can provide 69% or 63% protection respectively while ethanol, acetaldehyde or propanol can provide 50%, 35% and 24% respectively. In any case, protection exists as long as the organic additives were not completely consumed.
文摘Aging of ancient raw materials usually finish with disintegration, which starts on surface of walls to progress toward the inside mass of a huge variety of mineral compounds. This is particularly harmful when antique buildings keep mural paintings, which suffers destruction before the wall itself. Same case appears on sculptures and monuments, whose surfaces are often attacked by living organisms which start a deterioration process previous to complete disintegration. The main factor to produce these unwanted effects is humidity, either rain for materials exposed to open air, or underground humidity going up by capillarity of minerals, in this case represented by porosity of associated salts forming the material. This paper describes a method to measure easily the relative porosity of diverse raw materials at laboratory level, by using a radioactive labeled solution, and also a procedure to reduce their porosity of those minerals. The efficiency of this procedure is measured in the same way, and so the results obtained at laboratory level have encouraged its use at real scale, where it has been quite successful for a number of materials in a limited span of five years.
文摘Using 43 documented drill core samples of the H_5-chondrite 'Jilin' the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the second (4π-) irradiation stage of 'Jilin'. Relics of the track record of the first (2π-) exposure are indicated by a deviation from the theoretical depth profile of the 4π-exposure. No Pu-244 fission is observed ia the fission track background near the meteorite center. The atmospheric ablation thickness of the two drill cores A and B normal and parallel to the assumed surface of the 'Jilin' parent body was found to be 11±4 cm, respectively. A minimum shielding depth of the 'top' part of core A during the 2π-exposure is estimated to be～30 cm. Near surface deviations of the experimental track data from theory are ascribed to a short-term moderate heating event (equivalent to 24h,～370℃) no more than 0.4 Ma ago. The resulting partial track annealing in a surface layer of ～15—20 cm thickness of the preatmospheric body can explain the lack of GCR-tracks in Jilin samples from very shallow depths that are based on ^(60)Co measurements.
文摘The current industrial-scale production of molybdenum-99(^(99)Mo)and iodine-131(^(131)I)is heavily predicated on thermal neutron irradiation of LEU targets.In this route,^(99)Mo and ^(131)I are separated using a solid-phase extraction approach.The goal of this study was to develop and evaluate copolymeric beads that could be used to separate ^(99)Mo and ^(131)I from their aqueous solutions.Different aminated styrenedivinyl benzene co-polymeric beads were successfully manufactured for this approach.The structural features of the synthesized copolymers were characterized.The resin frameworks were found to have homogeneous spherical shapes decorated with a very thin layer of amine moieties.The FT-IR peaks caused by N—H stretching and C—N bending vibrations show the successful functionalization of the resins'surfaces with amine moieties selective for the sorption of I-over Mo O_(4)^(2-)ions.Under various circumstances,the produced resins were assessed for sorption of ^(99)Mo and ^(131)I from their aqueous solutions.They showed an enhanced sorption capability for I-ions compared to MoO_(4)^(2-)ions and attained equilibrium in less than 20 min.Data declare that the sorption of MoO_(4)^(2-)and I-ions onto synthesized resins was attained through an ion exchange process with Cl-ions.In such interactions,one iodide ion(I-)consumes only one active site from the resin surface,while two active sites must be exhausted to retain one MoO_(4)^(2-)ion onto the surface of the resins.The exchange interaction of both MoO_(4)^(2-)and I-ions was an endothermic process.Further,the elution of ^(99)Mo and ^(131)I radioisotopes loaded on synthesized resins was investigated using various eluents.Additional sets of individual and binary dynamic experiments were performed using columns packed with trimethylamine styrene divinyl benzene(TMA-PSDVB)and triethylamine styrene divinyl benzene(TEA-PSDVB)resins.The individual breakthrough sorption capacity of TMA-PSDVB and TEA-PSDVB resins had values of 381.6 and352.6 mg·g^(-1)for ^(131)I and values of 134.7 and 117.2 mg·g^(-1)for ^(99)Mo isotopes,respectively.Furthermore,TMA-PSDVB resin exhibited breakthrough sorption capacity for ^(99)Mo and ^(131)I,in the binary system,amounting to 123.7 and 331.6 mg·g^(-1)with elution percentages reaching 75.4%and 12.1%,respectively.These findings demonstrate that Mo(Ⅵ)ions were efficiently separated from I(Ⅰ)ions.Finally,the reported aminated polymeric resins may be regarded as promising solid phases for the separation and recovery of Mo(Ⅵ)and I(Ⅰ).
文摘Metal-substituted cobalt ferrites [MxCo(1-x)Fe2O4(M=Zn,Cu,Mn;x=0.0,0.25,0.5,and 0.75)]were synthesized via a sol-gel technique.The ferrite structures were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy,scanning electron microscopy,surface analysis using the Brunauer-Emmett-Teller method,and energy-dispersive X-ray spectroscopy.Antimicrobial activity of these ferrites against selected pathogenic microbes was determined.The structures remained cubic spinel phases after substitution of metals.Substitution strongly influenced the microstructure and homoge- neous grain distribution.The particle size of the ferrites increased linearly with increase in their annealing temperature.The surface area of zinc cobalt ferrite nanoparticles (ZCFO)was 52.56m^2/g,the average pore size was 1.84nm,and pore volume was 0.136mL/g.All ferrites showed antimicrobial activity toward all pathogens selected.Of these,the most powerful was ZCFO,showing zones of inhibition of 13.0mm against Bacillus subtilis and Staphylococcus aureus and 12.0mm against Candida albicans.Gamma-irradiated ZCFO nanoparticles (150.0kGy)maintained higher antimicrobial activity than non-irradiated particles,e.g. being active toward S.aureus (16.0mm).ZCFO is proposed as a candidate material for industrial and biomedical purposes.
