[en] A number of copolymers were synthesized by the reaction of N-vinyl carbazole (NVC) and divinylbenzene (DVB) by using the technique of suspension polymerization. A mixture of cyclohexanone (CHN) and petroleum ether of various composition was used as a diluent in the polymerization experiments. The copolymers were characterized for the density, pore volume, pore size distribution, surface area and mechanical strength. The copolymers were also converted into cation-exchange resin by sulfonation and the resulting resins were characterized for the ion-exchange capacity. The pore volume of the copolymers decreases from 1.26 to 0.19 ml/g and 1.09 to 0.46 ml/g with the decrease in pet. ether or increase in CHN ratio of organic phase, with the decrease in the amount of diluents as compared to monomers (F/sub s/) and with the decrease in the crossing agent, DVB, respectively, used in the respective polymerization experiments. The apparent density of the copolymers varies from 0.55 to 0.25 g/ml, 0.55 to 0.27 g/ml and 0.45 to 0.28 g/ml with the percentage increase in the ratio of pet. ether from 0 to 100% as compared to CHN, with the increase in solvent fraction from 0.3 to 0.8 and with the increase in DVB from 5 to 40%, respectively. The relatively larger size pores were observed in the beads of copolymers formed with the increase in the pet. ether contents of the diluents, increase in the amount of diluents as compared to monomers and also with the increase in the crossing agent. The capacity of NVC-DVB cation-exchange resins decrease slightly from 4.89 to 4.00 meq/g with the increase in the crosslinking agent from 5 to 40% whereas it does not change significantly with change in the composition and the amount of diluents used polymerization experiments under the given experimental conditions. The mechanical strength (crushing load) of the copolymer beads increased with the increase in CHN ratio from 0 to 100% in diluents mixture, with the decrease in solvent fraction from 0.8 to 0.3 and with the decrease in the crosslinking agent (DVB) from 40 to 5%. The crushing load also increase with the increase in the overall size of the copolymer beads. (author)

[en] Macroporous copolymer beads were synthesized by suspension copolymerization of N-vinyl carbazole (NVC) with divinylbenzene (DVB) in the presence of diluents, diethyl phthalate (DET) - petroleum ether (PE). This copolymer beads were characterized for their apparent density, pore volume, pore size distribution and surface area. The copolymer beads were converted into cation -exchange resin by sulfonation and the resulting resin was characterized for its ion - exchange capacity. The exchange behavior of Li/sup +/, Na/sup +/, K/sup +/ and Cs/sup +/ ions was investigated with the above mentioned cation -exchange resin in HCl concentration and also in the following order of alkali metal ions: Li/sup +/ < Na/sup +/ < K/sup +/ < Cs/sup +/. Based on the determination of the distribution coefficients of these alkali metal ions in HCl solution, the conditions most suitable of their quantitative separation are indicated and discussed. (author)

[en] The precision in measurement of trace level uranium isotopic ratio, i.e., ²³⁶U/²³⁸U or ²³⁴U/²³⁸U, on single Faraday detector with narrow dynamic range is very hard to achieve. This is mainly due to the narrow dynamic range of a single detector systems. A significant improvement in mass spectrometric determination of ²³⁶U/²³⁸U ratio has been achieved by employing an alternate method using a single Faraday detector of narrow dynamic range. The method makes use of the precise measurements of the ²³⁶U/²³⁴U ratio, ²³⁴U/²³⁵U ratio and ²³⁵U/²³⁸U ratio, which are used to calculate the ²³⁶U/²³⁸U ratio using the equation ²³⁶U/²³⁸U=²³⁶U/²³⁴Ux²³⁴U/²³⁵Ux²³⁵U/²³⁸U. Despite the fact that correlation of the data tends to increase the uncertainty in the result, our results show a significant improvement, i.e., more than 8 times better precision in measuring the ²³⁶U/²³⁸U ratio with this method (σ = 3.98x10^-08) as compared to direct measurement of ²³⁶U/²³⁸U (σ = 3.104x10^-07). The method widens the applicability of the single collector system with narrow dynamic range and it will potentially be helpful to improve the precision in the case of the static multi-collector system also. The objective of the present study was to compare the results of the same sample analyzed with the present alternate method and the direct method for precision. (author)

[en] The isotopic composition of lithium in seawater has been determined by thermal ionization mass spectrometry (TIMS) based on the use of lithium hydroxide as the ion source. Isotopic measurements in a reference material supplied by IAEA (L-SVEC Li₂CO₃) were made to check the reproducibility of the method and δ⁶Li indicates mobilization of light isotope of lithium form the sediment. (author)