Anthropogenic and natural environmental activities have led to the release of heavy and/or radioactive metals into the groundwater and soils, such as uranium-238 (U-238). A radioactive heavy metal with a relatively long half-life of 4.47 billion years, uranium, present in aqueous media as the uranyl cation UO22+, is detrimental to living organisms located near groundwater and soils. Inorganic materials such as ion-exchangers, extractants, and nanoporous sorbents have been previously investigated to remove U-238. However, with regards to the removal of heavy non-radioactive metals from aqueous solutions, recent research focuses on using biodegradable, recyclable, and organic biological wastes. This study aims to determine whether pistachio shells, which fit these criteria, can be used for the removal of uranyl ions from aqueous solutions. Batch sorption experiments were performed where the effects of pH, contact time, temperature, and initial uranyl concentration on uranyl uptake were investigated. In order to approximate the adsorption mechanism of uranyl by pistachio shells, the experimental data were fitted to kinetic models and to isotherm models. pH had a varied influence on uranyl uptake whereby high uptakes occurred at pH 4 and at a slightly alkaline medium. In addition, uranyl uptake by pistachio shells increased with greater contact time, initial uranyl concentration, and temperature, plateauing at approximately 2 h, 30 ppm U, and room temperature, respectively. The experimental data best fit pseudo-second-order and intraparticle kinetics models, and a Freundlich isotherm model. The pistachio shells were successfully demonstrated to be viable adsorbents for uranium in actual seawater samples, with trends observed to be similar to those that were achieved in the batch sorption studies.

Extraction of uranium from contaminated seawater using pistachio shells

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.