Gamma-ray induced decomposition of binary mixtures of potassium nitrate with 90, 70, 50, 30 and 10 mol% SiO2, Al2O3, MnO2, V2O5, La2O3, CeO2, Sm2O3, Eu2O3, Gd2O3 and Dy2O3 has been studied at different doses up to 500 kGy. Radiolytic decomposition of the nitrate is affected by the concentration
of the oxide in the binary mixture as well as by the absorbed dose. The enhancement is up to 103 times at 90 mol% of the additive.G(NO2−) values calculated on the basis of electron fraction of the nitrate decrease with the increasing concentration of the nitrate.
A comparison ofG(NO2−) for 90 mol% oxides shows decreasing trend as Gd2O3>Sm2O3≈Dy2O3> Eu2O3>CeO2>Al2O3>V2O5>SiO2>MnO2. ESR and TL measurements suggest the formation of radical species which interact with the radical species of nitrate causing
enhanced decomposition by energy transfer mechanism.
Gamma — radiolytic decomposition of sodium and potassium nitrates and its admixtures with respective cyanide and borate additives
has been studied over a wide absorbed dose range from 675 to 500 kGy. The decomposition of nitrate increases with the nature
and concentration of the additive in the admixture. The enhancement is more significant at >80 mol% of the additive.G(NO
) values, calculated on the basis of electron fraction of the nitrate salt, decrease with increasing concentration of the
nitrate. ESR spectral studies suggest the formation of radical species such as BO4 and BO
etc, in borates whereas in case of cyanide additive FH centres are produced. The radical species and colour centres so produced may then transfer their energy to nitrate and cause
enhancement in decomposition. A comparison with other oxyanion additives shows thatG(NO
) values decrease in the order PO
. Similarly, the nature of the cation also affects the decomposition.
Pyridine based thorium(IV) phosphate (PyThP) has been synthesized by drop-wise addition of the thorium(IV) nitrate with constant
stirring into a mixture of pyridine and phosphoric acid. This material has been characterized using X-ray, IR spectra, TG,
DTG and SEM studies in addition to its ion exchange capacity, elution and pH titrations. The material has been found amorphous
and fibrous in nature on the basis of X-ray diffraction and SEM studies. TG has revealed the changes incurred in the material
on thermal treatment and IR spectral studies have shown the presence of various groups in its structure.
A new phase of the hybrid fibrous ion exchanger, pyridine based cerium(IV) phosphate (PyCeP), has been synthesized in the
form of a sheet like paper by mixing ceric sulphate, phosphoric acid and pyridine in a particular ratio to get the material
of the optimum ion exchange characteristics. This material has been characterized with the help of ion exchange capacity,
elution and concentration and pH titrations behaviour in addition to some physicochemical studies like X-ray diffraction,
IR, TG, DTG and SEM studies. The SEM study confirms the fibrous nature of the material while amorphous nature is revealed
by its X-ray spectrum.
Reactions of recoil80, 80mBr with CH2ClBr and CCl3Br have been investigated. Relative reactivities of recoil bromine atoms in binary mixtures of CH2ClBr and CCl3Br with c–C6H12, CH3OH and C6H5N/CH3/2 have been determined using the model developed by Kontis and Urch.
Sorption behaviour of monovalent Rb+, Tl+ and Ag+ is studied on chromium fericyanide gel. Log Kd vs log concentration plots show that Rb+ and Tl+ are sorbed through ion exchange mechanism in a higher concentration range of ammonium nitrate or nitric acid, whereas the
adsorption of Ag+ is irreversible. It was found possible to elute Rb+ and Tl+ on the columns of this gel by 4 mol dm−3 NH4NO3 and 10 mol dm−3 HNO3, respectively. Binary separations of Rb+ and Tl+ from a number of other metal ions were achieved as other ions were found practically unadsorbed on these columns and were
eluted with water of pH 2–3. Achieved separations are of radioanalytical and analytical importance.
Authors:K. Varshney, V. Jain, A. Agrawal, and S. Mojumdar
Pyridine based zirconium(IV) phosphate (PyZrP)
and tin(IV) phosphate (PySnP) have been synthesized as new and novel intercalated
ion exchangers. These materials have been characterized using X-ray, IR spectra,
TG, DTG and DTA studies in addition to their ion exchange capacity, elution,
pH titration, concentration and distribution behaviour. The distribution studies
towards several metal ions in different media/concentrations have suggested
that PyZrP and PySnP are selective for Hg(II) and Pb(II), respectively. As
a consequence some binary separations of metal ions involving Hg(II) and Pb(II)
ions have been performed on a column of these materials, demonstrating their
analytical and environmental potential.