Uranium removal from nitric acid raffinate solution by solvent immobilized PVC cement
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Uranium removal from nitric acid raffinate solution by solvent immobilized PVC cement A. E. M. Hussein • M. H. Taha
Received: 23 April 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract The present work deals with uranium removal from a nitric acid raffinate (waste) solution using prepared solvent (tri-butyl phosphate, TBP) immobilizing PVC cement (SIC) as a suitable adsorbent. The studied relevant factors affecting uranium adsorption onto SIC adsorbent involved; contact time, solution molarity, initial uranium concentration and temperature. The obtained adsorption isotherm of uranium onto the SIC adsorbent was fitted to Langmuir, Freundlich and Dubinin–Radushkviech (D–R) adsorption models. The results showed that the obtained equilibrium data fitted well the Langmuir isotherm. Additionally, it was found that the adsorption process obeys the pseudo second-order kinetic model. On the other hand, the calculated theoretical capacity of our prepared SIC adsorbent reached about 17 g U/kg SIC. Uranium adsorption from the studied raffinate solution was carried out applying the attained optimum conditions. The obtained data showed that 58.4 mg U/5 g SIC were adsorbed. However, using of 2 M HNO3 solution as an eluent, 93 (54.3 mg U) from the adsorbed amount were eluted. Keywords Uranium Adsorption Elution PVC cement Nitric acid raffinate solution
Introduction The increasing quantities of uranium in the environment is closely tied to the nuclear activities [1].The toxic nature of uranium has been a public health problem for many years ago [2]. Therefore, it is necessary to remove, recover, A. E. M. Hussein (&) M. H. Taha Nuclear Materials Authority, Box 530, Maadi-Kattameya, Cairo, Egypt e-mail: [email protected]
concentrate and purify uranium in order to meet the energy demand for the future and prevent radioactive contamination of the environment. Many processes have been proposed for uranium removal from industrial wastewaters and radioactive wastes. Chemical precipitation [3], membrane processes, ion exchange, solvent extraction and adsorption are the most commonly used methods [4–8]. Adsorption has been found to be an effective and economic method with high potential for the removal, recovery and recycling of metal ions from wastewater. A number of materials, such as activated carbon [9], zeolite, olivine rock, smectites, kaolinite, bentonite, sepiolite [10], montmorillonite, biomass, goethite, and polymeric materials have been used for adsorption of uranium [6, 11, 12]. On the other hand, the prepared adsorbents i.e. solvent impregnated materials [13–17] gave high adsorption efficiencies. Our aim in the present work is the study of uranium removal from the raffinate solution by solvent (tri-butyl phosphate) immobilized PVC cement (SIC). Batch experiments were carried out in order study the effects of the relevant factors on uranium adsorption onto the SIC adsorbent. These factors involved: contact time, initial uranium concentration, solution acidity, solution temperature and weight to volume ratio
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