Influence of toxic elements on the simultaneous uptake of rare earth elements from contaminated waters by estuarine macroalgae

• Published in: Chemosphere (Oxford) 2020-08, Vol.252 (C), p.126562, Article 126562
• Main Authors: Costa, Marcelo, Henriques, Bruno, Pinto, João, Fabre, Elaine, Dias, Mariana, Soares, José, Carvalho, Lina, Vale, Carlos, Pinheiro-Torres, José, Pereira, Eduarda
• Format: Article
• Language: English
• Subjects: Bioremediation; Fucus; Mercury - metabolism; Metals, Rare Earth - metabolism; Potentially toxic elements; Rare earth elements; Recovery; Salinity; Seaweed - metabolism; Seaweeds; Ulva; Wastewaters; Water Pollutants, Chemical - metabolism; Water Pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126562

The present study tested whether the presence of potentially toxic elements (PTEs) (Cd, Cr, Cu, Pb, Hg and Ni), commonly found in wastewaters, interferes with the ability of macroalgae (Ulva intestinalis, Ulva lactuca, Fucus spiralis, Fucus vesiculosus, Gracilaria sp. and Osmundea pinnatifida) to remove rare earth elements (REEs) (La, Ce, Pr, Nd, Eu, Gd, Tb, Dy and Y), which are key elements for most high technologies (e.g. electronics, aerospace, renewable energy). Results proved the high capacity of living macroalgae to remove REEs from multielement solutions, with the following sequence of bioconcentration factors being observed: U. intestinalis (2790) > Gracilaria sp. (2119) > O. pinnatifida (1742) > U. lactuca (1548) > F. vesiculosus (944) > F. spiralis (841). Competition among REEs to sorption sites on the six macroalgae was minor due to the chemical similarities between the elements. However, Ce and Y were the less removed while Gd, La and Eu the most removed among REEs. Ionic strength was an important factor in the sorption process, with salinity affecting differently the six macroalgae. Surprisingly, the presence of potential toxic elements in solution enhanced the removal of REEs. The most plausible explanation is the preferentially complexation of those elements by carbonates over REEs, which facilitates the binding of REEs cations onto the surface of macroalgae. •REEs uptake in the presence of toxic elements by 6 living macroalgae was studied.•Both Ulva species and Gracilaria sp. were the macroalgae with the best performance.•Potentially toxic elements in solution enhanced the removal of REEs.•U. intestinalis concentrated >3000 times the REEs initially presented in solution.•Estuarie macroalgae have a high potential for the recycling of REEs in wastewaters.