Th(IV)/U(VI) Sorption on Modified SBA–15 Mesoporous Materials in Fixed–Bed Column

Abstract

The sorption of thorium and uranium ions by functionalized SBA–15 mesoporous silica materials with Schiff base ligating groups N–propylsalicylaldimine (SBA/SA) and ethylenediaminepropylesalicylaldimine (SBA/EnSA) from aqueous solution was investigated in fixed-bed column method. The TEMPeffect of pH, sample solution volume, and the column design parameters such as sample and eluent flow rates, and column bed height were studied. These investigations allowed to obtain the experimental breakthrough curves. Regardless to the adsorbent used, application of the columns with 2.5 cm bed height and sample flow rate 0.4 mL/min, resulted in the quantitative removal of 0.5 mg of Th(IV) and U(VI) ions from 200 and 250 mL aqueous solutions, adjusted at pH 4. The quantitative desorption of the loaded ions provided a preconcentration factor of 40 and 50 for Th(IV) and U(VI), respectively. Breakthrough studies showed the higher capacity of the column packed with SBA/EnSA in comparison to that packed with SBA/SA. The breakthrough curves indicated that both of the sorbents presents higher capacity towards uranium than thorium ions. The columns could be used for at least 3 sorption-desorption cycles. The investigated columns were examined for the recovery of Th(IV) and U(VI) from tap water and seawater samples.