Extraction chromatographic separation of thorium by silica gel impregnated with cyanex 923

Solvent impregnated silica gel material was prepared for thorium recovery from its aqueous nitrate solutions using the neutral phosphine oxide extractant, cyanex-923 in toluene. This was achieved by adsorption of the extractant onto the solid phase in three steps. The obtained adsorbent was characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The relevant factors of extraction such as influence of acid concentration, flow rate and impregnated cyanex 923 amount were optimized by equilibrium column experiments. The results revealed that thorium loaded on 0.5 g cyanex-silica achieved with about 99.6% efficiency. Selective elution of the loaded thorium was carried out in two steps using both sulfuric and hydrochloric acids after volume optimization. Based on the obtained optimum factors, validation of the studied impregnated solid phase occurred on three certified granite samples where the practical applicability was then examined upon two geological samples bearing Th(IV) collected from Abu Zeneima mineralization, South-Western Sinai. (author)