Platinum-group elements sorption by living macroalgae under different contamination scenarios

Abstract

Increasing emissions of Platinum-Group Elements (PGE) into marine environments may negatively impact ecosystems services and organisms wellbeing. Removing PGE from contaminated systems using efficient and low-cost technologies can therefore provide a sustainable solution to aquatic systems remediation. Previous studies highlight algae’s high binding ability to metals in solution. Assessing the viability of various algae species to remove PGE from contaminated solutions, while identifying differences in performance among algae and among elements, was the purpose of this study. For this, six macroalgae species (Ulva lactuca, Ulva intestinalis, Fucus spiralis, Fucus vesiculosus, Osmundea pinnatifida and Gracilaria sp., 3 g L−1) were exposed to PGE (Palladium, Rhodium, Ruthenium, Iridium and Platinum)-spiked seawater (10 and 500 µg L−1) for 72 h. Removal rates varied with time and among macroalgae and elements. Palladium was easily removed by all species (up to 83 %), while other PGE showed lower affinity to macroalgae. Removal sequence was Pd > Rh > Ru > Ir > Pt. Initial concentration rise induced faster and higher removal. U. lactuca performed best for all elements, while brown macroalgae were the less effective. Macroalgae external area and chemical composition were considered major factors influencing sorption, although each element and macroalgae should be examined individually. Results evidence living macroalgae (particularly U. lactuca) as a promising alternative to remediate PGE contaminated waters.