Response surface approach to optimize the removal of the critical raw material dysprosium from water through living seaweeds. (15th December 2021)

• Record Type: Journal Article
• Authors: Ferreira, Nicole; Fabre, Elaine; Henriques, Bruno; Viana, Thainara; Costa, Marcelo; Pinto, João; Tavares, Daniela; Carvalho, Lina; Pinheiro-Torres, José; Pereira, Eduarda
• Is Part Of: Journal of environmental management. Volume 300(2021)
• Publication Date: 2021-12-15
• Subjects: Process optimization -- Box-Behnken design -- Macroalgae -- Rare earth elements -- Biosorption; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2021.113697
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Dysprosium (Dy) is a rare earth element with a high economic and strategic value, and simultaneously an emerging contaminant, whose removal from wastewaters is gaining increasing attention. In this work, the Response Surface Methodology (RSM) combined with a Box-Behnken Design (3 factors-3 levels) was used to optimize the key operational conditions that influence the uptake of Dy by two living seaweed, Ulva sp . and Gracilaria sp.. The initial concentration of Dy (10–500 μg/L), water salinity (10–30), and seaweed dosage (0.5–5.5 g/L) were the independent variables, while the removal efficiency (%) and bioaccumulation ( q, μg/g) were the response variables. Results highlighted the high capacity of both species to capture Dy. After 168 h, the optimal conditions that led to a maximum of 91 % of Dy removed by Gracilaria sp. were: 500 μg of Dy per L of water, salinity 10, and 5.5 g of seaweed per L. For Ulva sp ., a maximum removal percentage of 79 % was achieved in the conditions: any initial concentration of Dy, salinity 20, and seaweed dosage of 3.7 g/L. Independently of the species, the response surfaces showed that the most important variable for the removal is the seaweed dosage, while for bioaccumulation is the initial concentration of Dy. Using RSM, it was possible to obtain the optimal operating conditions for Dy removal from waters, which is a fundamental step toward the application of the proposed technology at large scale. Graphical abstract: Image 1 Highlights: Dysprosium removal by two seaweeds was optimized by Response Surface Methodology. Assays followed a Box-Behnken Design with 3 factors in 3 levels. Gracilaria sp. and Ulva sp. reached 91 % and 79 % of Dy removal, respectively. For both species, model equations describing Dy removal and Dy uptake were derived. Seaweed dosage and initial concentration of Dy were the most influencing factors.