128 SUSTAINABLE APPROACHES TO URANIUM REMOVAL FROM WATER USING NATURAL BIOSORBENTS Zaid Al-Shomali1, Alcides Pereira2, Ana Clara3, *Maria De Lurdes Dinis1 1CERENA. Faculty of Engineering. University of Porto. Portugal. (*Presenting author: mldinis@fe.up.pt) 2 Laboratório de Radioatividade Natural. Faculdade de Ciências e Tecnologia da Universidade de Coimbra (LRN-FCTUC), Coimbra. Portugal 3CERENA. DEQ. Instituto Superior Técnico. Universidade de Lisboa. Lisboa. Portugal ABSTRACT Naturally occurring radionuclides are present in many water sources due to geological processes, industrial activities, and accidental releases. Several techniques have been employed worldwide to remove radionuclides from water. Adsorption, ion exchange, membrane filtration, chemical precipitation and electrodialysis are just a few of the available processes. Each method presents advantages and limitations. For example, chemical precipitation is recognized for its relatively low installation cost and effectiveness in removing a broad spectrum of radionuclides. However, this technique also generates a considerable volume of sludge, posing additional challenges. Ion exchange offers the benefits of producing a clean effluent and enabling metal recovery. Nonetheless, it is associated with higher installation costs and limited efficacy in removing specific radionuclides. On the other hand, adsorption is a cost-effective method for removing radionuclides from water. It is distinguished by its simple design, ease of operation, high efficiency, broad pH range, and straightforward adsorbent regeneration. Many adsorbent materials have proven highly effective in extracting radionuclides from aqueous media. However, in line with circular economy and zero-pollution approaches, abundant, low-cost, and eco-friendly "green adsorbents" have become a viable alternative to conventional synthetic materials used in water treatment. These green adsorbents are typically made from recycled forestry materials, agricultural and animal waste, and biological origins. This study investigates the potential of using natural biosorbents, such as Moringa Oleifera Seeds (MOS), to remove natural radionuclides, particularly uranium, from aqueous effluents. Adsorption tests were conducted using MOS and chitosan powders to compare removal efficiency. Chitosan is well known in the literature for its efficiency in removing uranium from contaminated water, achieving over 90-100% removal, depending on the specific chitosan-based material, modification and conditions. The MOS significantly outperformed Chitosan, achieving removal efficiencies of up to ~ 86 %, compared with Chitosan's maximum of ~ 35 % %. These initial trials with MOS showed high uranium removal rates, thereby justifying further research on its use as a natural absorbent. KEYWORDS Green adsorbents, Uranium, Moringa Oleifera, Adsorption
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