Extraction of long-lived radionuclides 152,154Eu and 134Cs using environmentally benign aqueous biphasic system

Cesium-induced inhibition of bacterial growth of Pseudomonas aeruginosa PAO1 and their possible potential applications for bioremediation of wastewater

Radioactive isotopes and fission products have attracted considerable attention because of their long lasting serious damage to the health of humans and other organisms. This study examined the toxicity and accumulation behavior of cesium towards P. aeruginosa PAO1 and its capacity to remove cesium from waste water. Interestingly, the programmed bacterial growth inhibition occurred according to the cesium environment. The influence of cesium was analyzed using several optical methods for quantitative evaluation. Cesium plays vital role in the growth of microorganisms and functions as an anti-microbial agent. The toxicity of Cs to P. aeruginosa PAO1 increases as the concentration of cesium is increased in concentration-dependent manner. P. aeruginosa PAO1 shows excellent Cs removal efficiency of 76.1% from the contaminated water. The toxicity of cesium on the cell wall and in the cytoplasm were studied by transmission electron microscopy and electron dispersive X-ray analysis. Finally, the removal of cesium from wastewater using P. aeruginosa PAO1 as a potential biosorbent and the blocking of competitive interactions of other monovalent cation, such as potassium, were assessed. Overall, P. aeruginosa PAO1 can be used as a high efficient biomaterial in the field of radioactive waste disposal and management.

A dynamic chitosan-based self-healing hydrogel with tunable morphology and its application as an isolating agent

A biopolymer chitosan based hydrogel with good transparency and rapid self-healing activity has been synthesized and utilized to get high purity separation of ¹⁵²Eu (T_1/2 = 13.33 a) and ¹³⁷Cs (T_1/2 = 30.17 a) employing SLX technique.

Aqueous biphasic separation of97Ru and95,96Tc from yttrium

An aqueous biphasic separation technique has been developed for the separation of⁹⁷Ru, a potential candidate radionuclide in nuclear medicine, from its target matrix, yttrium.

Selective separation of 152Eu from a mixture of 152Eu and 137Cs using a chitosan based hydrogel

A rapid and novel technique was developed to separate long-lived fission products ¹⁵²Eu (T_1/2 = 13.33 years) and ¹³⁷Cs (T_1/2 = 30.17 years) using a solid liquid extraction (SLX) technique with a chitosan biopolymer based hydrogel (ChG).

Biosorption behavior and mechanism of cesium-137 on Rhodosporidium fluviale strain UA2 isolated from cesium solution

In order to identify a more efficient biosorbent for (137)Cs, we have investigated the biosorption behavior and mechanism of (137)Cs on Rhodosporidium fluviale (R. fluviale) strain UA2, one of the dominant species of a fungal group isolated from a stable cesium solution. We observed that the biosorption of (137)Cs on R. fluviale strain UA2 was a fast and pH-dependent process in the solution composed of R. fluviale strain UA2 (5 g/L) and cesium (1 mg/L). While a Langmuir isotherm equation indicated that the biosorption of (137)Cs was a monolayer adsorption, the biosorption behavior implied that R. fluviale strain UA2 adsorbed cesium ions by electrostatic attraction. The TEM analysis revealed that cesium ions were absorbed into the cytoplasm of R. fluviale strain UA2 across the cell membrane, not merely fixed on the cell surface, which implied that a mechanism of metal uptake contributed largely to the cesium biosorption process. Moreover, PIXE and EPBS analyses showed that ion-exchange was another biosorption mechanism for the cell biosorption of (137)Cs, in which the decreased potassium ions were replaced by cesium ions. All the above results implied that the biosorption of (137)Cs on R. fluviale strain UA2 involved a two-step process. The first step is passive biosorption that cesium ions are adsorbed to cells surface by electrostatic attraction; after that, the second step is active biosorption that cesium ions penetrate the cell membrane and accumulate in the cytoplasm.

Application of PEG based aqueous biphasic systems in extraction and separation of no-carrier-added 183Re from bulk tantalum

No-carrier-added (nca) rhenium isotopes (182,182m,183Re) were produced by irradiation with 30 MeV α particles on natural tantalum target. The short-lived 182,182mRe were allowed to decay and long-lived nca 183Re was separated from bulk tantalum matrix by aqueous biphasic system (ABS) using 2 M solutions of nine different salts, namely, Na2SO4, Na2SO3, NaHSO3, Na2S2O3, Na2HPO4, Na2CO3, Na-citrate, Na-tartrate, and (NH4)2SO4 as salt rich phases against 50% (w/w) PEG-4000 as polymer rich phase at room temperature. The influence of temperature and thermodynamic parameters Δ Hº and Δ Sº were obtained for the partition of 183Re and tantalum in these systems. Nca 183Re was extracted in high amount in polymer rich phases irrespective of the salt rich phases. Bulk tantalum showed tendency to remain in salt rich phases. ABSs with PEG-4000 polymer rich phase in combination with Na2SO4, Na2SO3, NaHSO3, Na2HPO4, Na2CO3, Na-citrate and Na-tartrate as salt rich phases at basic pH and at ambient temperature (27 ºC) offered single-step separation between nca 183Re and bulk Ta. When Na2S2O3 and (NH4)2SO4 were used as salt rich phase, slight extraction of bulk tantalum was observed in PEG-4000 rich phase. The dynamic dissociation constant of 183Re-PEG-4000 complex was measured by dialysis of the PEG-rich phase against de-ionised water. The k dissociation value was found as low as 0.0185 min−1. Therefore, it is possible to have pure 183Re in de-ionized water immediately after the dialysis.