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Amidoxime (AO)-functionalized polymer sorbents used in this study were prepared by two different routes involving UV grafting and electron-beam grafting of acrylonitrile (AN) into poly(propylene) fibrous and microporous sheets, and subsequent conversion of AN to AO groups by reacting the precursor sorbent with hydroxylamine. The values of self-diffusion coefficient (D(s)) of UO(2)(2+) in fibrous and sheet AO sorbents were found to be 1.1 x 10(-6) and 2.3 x 10(-10) cm(2) s(-1), respectively. The higher diffusion mobility of UO(2)(2+) in the fibrous AO sorbent was attributed to its higher free volume as observed in scanning electron microscopic studies. The water content was also found to be maximum in AO-fibrous sorbent (165-200 wt %) and minimum in AO-sheet sorbent (70 wt %). In fibrous AO sorbent, the values of D(s) for Na(+) and Sr(2+) were found to be comparable to their self-diffusion coefficients in the aqueous medium. This indicated that the retardation in diffusion mobility of the ions was a minimum in the fibrous AO sorbent. However, D(s) of UO(2)(2+) in the fibrous membrane was found to be significantly lower than that of Sr(2+), which has a self-diffusion coefficient comparable to that of UO(2)(2+) in aqueous medium. This could be attributed to stronger binding of UO(2)(2+) with AO groups as compared to Sr(2+). To understand the parameters affecting the U(VI) sorption from seawater, the U(VI) exchange rates between fibrous AO sorbent (S) and seawater (aq) involving (H(+)/Na(+))(S) right harpoon over left harpoon ([UO(2)(CO(3))(3)](4-))(aq) and (UO(2)(2+))(S) right harpoon over left harpoon ([UO(2)(CO(3))(3)](4-))(aq) systems were experimentally measured. The exchange profiles thus obtained were found to be non-Fickian and much slower than (H(+))(S) right harpoon over left harpoon (UO(2)(2+))(aq) and (UO(2)(2+))(S) right harpoon over left harpoon (UO(2)(2+))(aq) exchanges. This seems to suggest that the reaction kinetics involved in decomplexation of [UO(2)(CO(3))(3)](4-) into UO(2)(2+), which forms a complex with AO groups, is the rate-determining step in sorption of U(VI) from seawater. The kinetics of U(VI) sorption in AO-gel and AO-fibrous sorbents followed the pseudo-second-order rate equation. The density of AO groups in the sorbents and their conditioning were found to influence the U(VI) sorption from seawater.

Nuclear power reactors are operating in 31 countries around the world. Along with reactor operations, activities like mining, fuel fabrication, fuel reprocessing and military operations are the major contributors to the nuclear waste. The presence of a large number of fission products along with multiple oxidation state long-lived radionuclides such as neptunium ((237)Np), plutonium ((239)Pu), americium ((241/243)Am) and curium ((245)Cm) make the waste streams a potential radiological threat to the environment. Commonly high concentrations of cesium ((137)Cs) and strontium ((90)Sr) are found in a nuclear waste. These radionuclides are capable enough to produce potential health threat due to their long half-lives and effortless translocation into the human body. Besides the radionuclides, heavy metal contamination is also a serious issue. Heavy metals occur naturally in the earth crust and in low concentration, are also essential for the metabolism of living beings. Bioaccumulation of these heavy metals causes hazardous effects. These pollutants enter the human body directly via contaminated drinking water or through the food chain. This issue has drawn the attention of scientists throughout the world to device eco-friendly treatments to remediate the soil and water resources. Various physical and chemical treatments are being applied to clean the waste, but these techniques are quite expensive, complicated and comprise various side effects. One of the promising techniques, which has been pursued vigorously to overcome these demerits, is phytoremediation. The process is very effective, eco-friendly, easy and affordable. This technique utilizes the plants and its associated microbes to decontaminate the low and moderately contaminated sites efficiently. Many plant species are successfully used for remediation of contaminated soil and water systems. Remediation of these systems turns into a serious problem due to various anthropogenic activities that have significantly raised the amount of heavy metals and radionuclides in it. Also, these activities are continuously increasing the area of the contaminated sites. In this context, an attempt has been made to review different modes of the phytoremediation and various terrestrial and aquatic plants which are being used to remediate the heavy metals and radionuclide-contaminated soil and aquatic systems. Natural and synthetic enhancers, those hasten the process of metal adsorption/absorption by plants, are also discussed. The article includes 216 references.

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SummaryThe effect of temperature on the extraction behaviour of Am(III), Pu(IV) and U(VI) from nitric acid medium was studied employing