Thorium(IV) reacts with 1-(2′-thiazolylazo)-2-naphthol (TAN) in the presence of antipyrine to form a sparingly soluble red-coloured chelate, soluble in ≥36% methanol (v/v). Complexation takes place instantaneously at pH 2.4–2.8, maintained by glycine buffer. Antipyrine is found to enhance sensitivity of the complex, which is stable for 19 hours. The 1∶2 complex exhibits maximum absorbance at 555 nm, obyes Beer's law in the concentration range from 0.32 to 6.56 μg of thorium(IV) per ml, has a molar absorptivity of 3.14·104 dm3/mol−1·cm−1 and a Sandel sensitivity of 7.4 ng·cm−2. The formation constant (log K) is found to be 8.62 and 8.45. Interference of 57 anions and cations in the determination of thorium(IV) has been studied. From ten repeated determinations, the coefficient of variation was found to be ±0.98%. The method was successfully applied for determination of thorium content in a sample of monazite.

Rapid spectrophotometric determination of thorium(IV) with 1-(2′-thiazolylazo)-2-naphthol

In this study we investigate the basic features of thorium adsorption from aqueous systems by silk fibroin. Our previous study showed that this biopolymer has high efficiency for U(VI) adsorption. It is well-known that thorium, which is a tetravalent metal, is a more reactive element than uranium. Thorium(IV) adsorption proves to be very rapid and dependent on pH, temperature, retention time, concentration of ion, amount of fibroin, volume of solution and volume-to-mass ratio.

Separation of thorium from aqueous solution using silk fibroin

The limit of detection (LOD) improvement in TLC determination of uranium and thorium in presence of other metal ions is presented in this paper. The mobile phase system contains iso-propyldithiophosphotic acid (i-PrDTP), as a complexing agent, in order to differentiate the studied species by modifying their retention. The paper reports the successful separation and the quantitative determination of uranium and thorium in the presence of other metal ions in the concentration range 2.5–30 μg/μl.

The limit of detection improvement in TLC determination of uranium and thorium in the presence of other metal ions

Application of extraction chromatography to the preparation of high-purity scandium oxide

Thorium was extracted at pH 5.0 from 0.01 M malonic acid on a column of silica gel coated with Amberlite LA-1. Thorium was separated from alkali and alkaline earths, managenese, iron, cobalt, nickel, zinc, tin, in binary mixtures by taking advantage of the difference in the pH of formation of malonato complexes. Thorium was separated from zirconium, uranium, scandium, molybdenum, titanium, by exploiting the difference in the stability of malonato complexes. The method was extended for the analysis of thorium in monazite.

Reversed phase extraction chromatographic separation of thorium with amberlite LA-1 from malonate solutions

Reversed phase extraction chromatographic separation of thorium with amberlite la-1 from malonate solutions

Zirconium was separated by extraction chromatography with Amberlite LA-l as an extractant from 1 × 10−3 M to 2.5 to 10−1 M of malonic acid at pH 2.0 to 6.0. It was stripped with various mineral acids and determined spectro-photometrically with arsenazo-III at 665 nm. Zirconium was separated from alkali, alkaline earths, yttrium, lanthanum, chromium(III), manganese, cobalt, nickel, copper, zinc, cadmium and aluminium by process of selective extraction. It was also separated from scandium, titanium, thorium, uranium and bismuth by process of selective stripping with various mineral acids. The method was extended for the analysis of zirconium in zircon.

Prakash Narayanan

Papers

Reversed phase extraction chromatographic separation of thorium with amberlite LA-1 from malonate solutions

Reversed phase extraction chromatographic separation of thorium with amberlite la-1 from malonate solutions

Separation of zirconium by extraction chromatography with amberlite LA-1 from malonic acid