Biosorption of lanthanum using Sargassum fluitans in batch system

Separation and purification of lanthanum from other rare-earth (RE) elements are highly complex processes comprising several steps of extraction using organic solvents or ion-exchange resins at high costs. In order to study the biosorption process as an alternative for conventional lanthanum recovery, this work investigated some basic aspects of lanthanum–Sargassum biomass interactions in batch equilibrium contact. The dynamics of biosorption, influence of pH, and the desorption of this RE were investigated. Maximum biosorption coefficient (qmax) increased from 0.05 at pH 2 to 0.53 mmol g−1 at pH 5 for lanthanum sulfate. When lanthanum chloride was used, a higher qmax at pH 5 (0.73 mmol g−1) was observed as compared to the sulfate salt (qmax=0.53 mmol g−1) at the same pH. Adsorption and desorption curves pointed out a complete recovery of metal adsorbed in the Sargassum fluitans biomass, showing a reversibility of this process and indicating the potential of biosorption for lanthanum removal and recovery.