Sorptive flotation of Eu(III)-loaded clays from aqueous solutions

Abstract

The present paper investigates the removal of Eu(III) from aqueous solutions by a sorptive flotation process. Eu(III) removal is achieved by adsorption onto bentonite and kaolinite followed by floatation using sodium dodecyl sulfate(SDS) and cetyltrimethylammonium bromide(CTAB) collectors. The effect of adsorption parameters (pH, contact time, clay weight, and initial Eu(III) concentration) as well as flotation parameters (collector and frother concentrations, and bubbling time) on the removal efficiency of Eu(III) were studied. Results show that Eu(III) ions are removed efficiently (∼95%) at pH = 4 after 1h shaking with clays and 15min floatation Keywords: sorptive flotation, radioactive waste, europium, bentonite, kaolinite 1.Introduction Radioisotopes of europium (ex: 152 Eu and 154 Eu) are of the most hazardous contaminants present in radioactive wastewater due to their relatively high energy (hard γ-emitters) and long half-lives.[For 152 Eu(T 1/2 =13.2y) three γ-lines 122,344 and 1408 keV, For 154 Eu(T 1/2 =8.5 y) two γ-lines 123 and 1274 keV]. Besides, Eu(III) is usually taken as homologue for trivalent actinides because the ionic radii of Eu(III) is almost the same for all the trivalent lanthanides and actinides, which result in a similar physicochemical behavior of Eu(III) with the trivalent lanthanides and actinides. Removal of radioactive contaminants is essential for environmental pollution control. Several techniques are available for the removal of hazardous ions from aqueous solutions including chemical precipitation, solvent extraction, micellar ultrafiltration, organic and inorganic ion exchangers and adsorption. Among these, the adsorption technique is considered very important because of its cost effective treatment, easy operation, narrow space for building the plant, no chemical reagents needed and no sludge produced. Natural clays are considered as a low-cost adsorbent for this purpose (Hennig et al., 2002). Various types of clays as low-cost adsorbents for heavy metal removal have been reported (Katsumata et al., 2003). Bentonite and