Selective biosorption and recovery of scandium using the alga Fucus vesiculosus
Laura Castro, Nelly Abrahamyan, Arevik Vardanyan, F. González, Narine Vardanyan, J.A. Muñoz
Abstract
• The brown alga Fucus vesiculosus is an efficient adsorbent for Sc. • The optimum pH value is 3 and the maximum adsorption capacity is 1.09 mmol Sc·g −1 . • F. vesiculosus has higher affinity for Sc than for Al. • Solutions containing Sc and Al can be treated in continuous biosorption columns. • Sc can be desorbed with 0.1 N citric acid favouring the recycling of the adsorbent. The goal of this work was to study the viability of the application of biosorption using the brown alga Fucus vesiculosus in the recovery of scandium from red mud. The highest affinity of the biosorbent for scandium and aluminium was at pH 3. Sorption isotherms fitted to the Langmuir model for scandium and aluminium with adsorption capacities as high as 1.04 mmol·g −1 for both metals but with higher affinity for scandium than for aluminium. The performance of the biomass in fixed-bed columns was evaluated in different experimental conditions (flow rate, bed height and inlet metal concentration). Metal desorption was achieved with different inorganic and organic acids. After three consecutive sorption–desorption cycles using 0.1 N citric acid and deionized water during the regeneration step, the brown alga showed a progressive increase in scandium uptake due to the cross-linking citric acid and the alginate chains. The biomass was characterized before and after biosorption using Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) coupled with an energy dispersive elemental analyser (EDS). The sorption involves different functional groups, such carboxylate and sulphonic groups by chelation and electrostatic interactions.