Production of a new adsorbent from Moroccan oil shale by chemical activation and its adsorption characteristics for U and Th bearing species

New adsorbents were prepared from Moroccan oil shale of Tarfaya (layer R3) by chemical activation with sulphuric acid diluted at 80%. The influence of activation temperature, atmosphere gas, holding time in oven and weight ratio of sulphuric acid to precursor was investigated by determination of yield of adsorbents and adsorption capacity of methylene blue. The best adsorbent properties were found for a particular combination of the chosen parameters: temperature and time of activation respectively equal to 250$^{\circ}$C and 2 hours, the gas vector being nitrogen (N$_{2})$. The adsorption capacity for methylene blue and specific surface (S$_{\rm BET})$ of the new adsorbent were equal to 300 mg/g and 270 m$^{2}$/g respectively. The batch mode experiment was used to explore the feasibility of this adsorbent for removal of radionuclides (U and Th) from aqueous solution. Applicability of the adsorbent was examined for synthetic solution prepared from hydrated uranyl nitrate (UO$_{2}$(NO$_{3})_{2}$.6H$_{2}$O) and hydrated thorium nitrate (Th(NO$_{3})_{4}$.5H$_{2}$O). The parameters of adsorption for the two radioelements were determined by application of the Langmuir, Freundlich and Elovich models