Species dependent studies of no-carrier-added (93m)Mo: A green method.

The present paper reports a combination of radioanalytical and green methodology for the ultra-trace scale speciation of molybdenum. The differential attitude of iron-doped calcium alginate (Fe-CA) and chitosan biopolymers towards no-carrier-added (93m)Mo radionuclide was studied to develop environmentally sustainable speciation methodology in ultra-trace scale. The affinity of (93m)Mo towards the Fe-CA beads is greater than that of chitosan. Species information was obtained by comparing the adsorption profile of (93m)Mo on Fe-CA and chitosan biopolymer with the software code CHEAQS PRO program. From the experimental results it is concluded that no-carrier-added (93m)Mo radionuclide form mononuclear species instead of polynuclear species in aqueous solution. Use of biodegradable, non-toxic biopolymer makes this method a step forward towards green chemistry.

Production of 93mMo through natY(7Li, 3n) reaction and subsequent studies on separation and extraction behaviour of no-carrier-added 93mMo from an yttrium target.

The present work reports heavy-ion-assisted production of (93m)Mo from a natural yttrium target using the (89)Y((7)Li, 3n)(93m)Mo reaction. Three different methodologies based on liquid-liquid extraction (LLX), aqueous biphasic extraction and precipitation, have been developed for separation and extraction of no-carrier-added (nca) (93m)Mo (T(1/2)=6.85h) radionuclide from bulk yttrium target. Complete separation of nca Mo from the target Y has been achieved by employing LLX technique with 0.1M trioctylamine (TOA) dissolved in cyclohexane and 8M HCl. Quantitative separation of (93m)Mo from the yttrium target is also possible by precipitating bulk yttrium with 1M oxalic acid. However, for this particular case, studies have shown that the aqueous biphasic extraction is not the method of choice for separation of nca Mo. Nevertheless, the extraction pattern is important in the context of simulation experiments for studying the behaviour of (106)Sg. Similarity or dissimilarity between the extraction patterns in various analytical systems will be helpful to decisively place Sg in the right position in the periodic table.

Uptake studies of environmentally hazardous (51)Cr in Mung beans.

Attempt has been made to study the accumulation behaviour of a common plant, Mung bean (Vigna radiata) towards Cr(III) and Cr(VI) to have an insight on the migration and bio-magnification of Cr. For this purpose healthy germinated Mung bean seeds were sown in the sand in the presence of Hoagland's nutrient solution containing measured amount of K(2)(51)Cr(2)O(7) and (51)Cr(NO(3))(3).9H(2)O. Growth rate was also studied in the presence and absence of phosphate salts in the medium. It has been found that the transfer of chromium from soil to plant is significantly low (maximum 5% for both Cr(III) and Cr(VI)). Maximum accumulation of Cr occurs in the root with respect to the total chromium accumulation by the plant. Other parts of the Mung bean plant, e.g. cotyledons, shoot and leaves, show negligible accumulation. Therefore, the chance of direct intake of Cr through food as well as through the grazing animals to human body is less.

Separation of no-carrier-added 66,67Ga produced in heavy ion-induced cobalt target using alginate biopolymers.

Heavy ion activation of natural cobalt foil with 84MeV (12)C results in the formation of no-carrier-added (nca) (66,67)As radionuclides, along with their corresponding decay products, (66,67)Ge and (66,67)Ga, in the matrix. Because arsenic and germanium radionuclides are short-lived, after a cooling period of 10h only nca gallium radionuclides remain in the matrix. We attempted to separate the nca gallium radionuclides from the target matrix cobalt by biopolymeric calcium alginate (CA) and Fe-doped calcium alginate (Fe-CA) beads. A complete separation has been achieved by adsorbing (66,67)Ga and a lesser amount of bulk cobalt at pH 3 on Fe-CA beads, followed by desorbing cobalt from the beads with 0.4M NaNO(2).

Speciation-dependent studies on removal of arsenic by iron-doped calcium alginate beads.

This work aims to study the differential attitude of Fe-doped calcium alginate (Fe-CA) beads towards As(III) and As(V) compounds so that speciation-dependent environmentally sustainable methodologies can be developed for removal of arsenic from contaminated water. Throughout the experiment, (76)As has been used as precursor of stable arsenic. The affinity of As(V) towards the Fe-CA beads is greater than that of As(III). Removal efficiency of Fe-CA beads for As(V) increases with increasing number of beads and longer shaking times. At pH 3, 30 Fe-CA beads remove As(V) completely from a solution containing 20mgkg(-1) As(V). The technique has been successfully applied to the ground water collected from an arsenic-contaminated area.

Biosorption of no-carrier-added radionuclides by calcium alginate beads using 'tracer packet' technique.

The aim of this study was to determine the adsorption behaviour of various micronutrient elements e.g., (61)Cu, (62,63)Zn, (66,67,68)Ga, (66,67,69)Ge, (71,72)As present in no-carrier-added state, with calcium alginate (CA) using 'tracer packet' technique. High Ge and Ga and moderate Cu removal were achieved at pH 7 and pH 5, respectively. Results on the studies to recover all the three radionuclides from the calcium alginate beads using desorbing reagents, HCl, thiourea, ammonium oxalate and sodium nitrite showed that 0.1 M HCl and 0.1 M ammonium oxalate removed Cu and Ge moderately. The amount of Ga desorbed by all the washing liquids was almost negligible, except sodium nitrite.

Separation of no-carrier-added 52Mn from bulk chromium: a simulation study for accelerator mass spectrometry measurement of 53Mn.

53Mn radionuclide (T(1/2) = 3.7 x 10(6) y) is produced through the interaction of cosmic rays. Measurements of concentrations of 53Mn in rocks might help to understand Earth surface processes that occurred in time periods not accessible with other cosmogenic nuclides. Only accelerator mass spectrometry (AMS) can determine such ultratrace levels of 53Mn. The main interference in the detection of 53Mn by AMS is its stable isobar 53Cr, which is roughly approximately 10(12) times more abundant in nature. A prerequisite of any AMS measurement of 53Mn in geological samples is therefore chromium separation by an efficient chemistry. Thus, we have developed a method for the separation of chromium and manganese by using a radiometric simulation. The separation procedure was monitored by 51Cr (T(1/2) = 27.70 d) and 52Mn (T(1/2) = 5.59 d) as the corresponding radiotracers for chromium and manganese, respectively. The separation studies were performed by a liquid-liquid extraction technique using trioctylamine (TOA) diluted in cyclohexane. A high separation factor (approximately 16 000) for Mn and Cr can be obtained at optimal conditions of 0.8 M TOA and 9 M HCl. The developed method has been found equally applicable for real geological samples such as manganese crusts, lava, and sediment samples. Therefore, the method offers an important tool to improve 53Mn measurements by AMS.

Incorporation of thiosemicarbazide in Amberlite IRC-50 for separation of astatine from alpha-irradiated bismuth oxide.

A chelating resin was synthesized by incorporating thiosemicarbazide into Amberlite IRC-50, a weakly acidic polymer. Astatine radionuclides produced by alpha-irradiating bismuth oxide were separated using the newly synthesized chelating resin. The resin showed high selectivity for astatine. The adsorbed astatine was recovered using 0.1M EDTA at pH approximately 10.

Radiochemical separation of carrier-free 204,206 Bi from alpha-irradiated thallium oxide target.

Alpha activation of Tl(2)O(3) target results in the formation of carrier-free 204,206 Bi. Two different radiochemical methods were used for the separation of bismuth radionuclides from the target matrix. A very high separation factor was achieved using liquid-liquid extraction (LLX) method with methyl isobutyl ketone (MIBK)-HCl system. Solid-liquid exchange adsorption was carried out using a novel inorganic ion exchanger, zirconium vanadate from HCl medium. The separation was found to be maximum around pH 2.

Synthesis of a new ion exchanger, zirconium vanadate, and its application to the separation of barium and cesium radionuclides at tracer levels.

A new inorganic ion exchanger, zirconium vanadate, has been synthesized and characterized. Elemental analysis suggests that the probable formula of the compound is ZrO2, V2O5, 2H2O. The exchanger is highly stable in thermal, radiation and chemical environments. Radiochemical separation schemes for the 134Cs and 133Ba pair and also for separating the short-lived daughter 137Ba from its parent 137Cs using this newly synthesized ion exchanger have been developed.

Alternative radiochemical heavy ion activation methods for the production and separation of thallium radionuclides.

Heavy ion activation of natural gold foil with a 7Li beam results in the formation of carrier-free 199-201Pb radionuclides along with their corresponding decay products, 199-201Tl, in the matrix. At 49 MeV projectile energy, the production of 199Tl through its precursor 199Pb is maximal, while that of other. thallium radionuclides is minimal. Another way for the direct production of carrier-free thallium radionuclides is to irradiate natural platinum foil with a 7Li beam; on this case, production of 199Tl is maximal at 43 MeV projectile energy. The carrier-free thallium radionuclides have been separated from the bulk target matrix gold and platinum by liquid-liquid extraction using trioctylamine as a liquid anion exchanger.