Sequestration of U(VI) from aqueous solutions using precipitate ion imprinted polymers endowed with oleic acid functionalized magnetite Nikita Tawanda Tavengwa • Ewa Cukrowska • Luke Chimuka Received: 10 November 2014 Ó Akade ´miai Kiado ´, Budapest, Hungary 2014 Abstract The use of a polymeric sorbent material embedded with oleic acid coated magnetic particles as selective sorbents for the removal of U(VI) ions from industrial waste effluents was studied. In the presence of other competing ions [Th(IV) and Ni(II)], U(VI) was preferentially adsorbed. Inclusion of nano-magnetic parti- cles in the polymer matrix aided the separation of the sorbents from aqueous solutions by application of external magnetic field. High recoveries indicated that the sorbent is suitable for application in contaminated water. Keywords Magnetic imprinted polymer  Precipitate  Uranium  Oleic acid Introduction Although uranium is only present in minute concentration in seawater, its recovery from the ocean has been under serious consideration for several decades with a view for enhancing uranium reserves and avoiding the environmental impact of uranium mining [1]. Uranium is a potential environmental pollutant, especially in mining industrial wastewater, and its migration in nature is therefore important in this context. In view of the anticipated exhaustion of terrestrial uranium reserves in the near future, research has been directed towards the recovery of uranium from many sources which include natural waters [2]. Various methods have been reported regarding the removal of heavy metals from wastewaters which include thermal, biological, physical, and chemical treatments [3–5]. However, most of these methods are expensive and difficult to implement. There is therefore a serious need for the development of easy and low cost methods. Adsorbents are the most important materials examined for the removal of toxic metal ions due to their inexpensive and effective nature. Adsorption processes provide a feasible treatment, especially if the adsorbent is inexpensive and readily available [5–7]. Many organic and inorganic adsorbents containing dif- ferent functional groups, which show sequestration of uranyl ions have been synthesized and used for the sepa- ration of uranium from aqueous solutions [8]. Most inor- ganic adsorbents have limitations on adsorption rates and have poor mechanical stability under marine conditions [9, 10]. On the other hand, numerous investigations have been carried out on organic adsorbents and have shown good uranium loadings [11, 12]. However, one of the main reasons for many traditional sorbents not becoming that much popular is their non-specific removal of a particular analyte from complex matrix. An alternative approach involves the use of biomimetic receptor systems, or plastic antibodies capable of binding target analytes with high affinities and selectivities on par with natural receptors [13, 14]. Molecular or ion imprinting is one such technique, and is generally defined as a syn- thetic approach by which a molecular receptor is assembled via template-guided synthesis [15, 16]. The binding sites are created by polymerizing functional and cross-linking monomers in the presence of the target. At low pH, ura- nium normally exists as a uranyl ion and was used as a template in this research. Hydrolysis of the uranyl ions in aqueous solution is significant at high pH values. A larger number of uranyl hydroxides, oxyhydrates and uranates are known [17]. Studies have been done on the uptake of uranium using the imprinting technique [18–21]. N. T. Tavengwa (&)  E. Cukrowska  L. Chimuka School of Chemistry, Molecular Sciences Institute, University of Witwatersrand, Private Bag 3, Johannesburg 2050, South Africa e-mail: nikita.tavengwa@students.wits.ac.za 123 J Radioanal Nucl Chem DOI 10.1007/s10967-014-3878-3