2010 Volume 59 Issue 11 Pages 623-636
In order to evaluate the efficiency of seaweed biomass as sorbent for rare earth elements(REEs), sorption experiment from aqueous solutions containing known amount of lanthanide(La, Eu or Yb) using three kinds of Ca-loaded dried seaweeds(brown algae:Sargassum hemiphyllum, green algae:Ulva pertusa and red algae:Schizymenia dubyi) in single component system was explored. Furthermore, the sorption mechanism of these elements was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, to confirm the characteristics of the seaweed biomasses, the surface morphology of the biomass before and after metal adsorption was determined by Scanning Electron Microscope(SEM).
Consequently, the following matters have been mainly clarified. (1)The morphology of Sargassum hemiphyllum and Ulva pertusa surface has hardly changed even after exposing to metals. On the other hand, the change of the surface condition on Schizymenia dubyi after adsorption was observed. (2)Adsorption isotherms using the seaweed biomass can be described by Langmuir and Freundlich isotherms satisfactorily for lanthanide. These adsorption may have occurred mainly by monolayer reaction because of better-fitting for Langmuir model. (3)The seaweed biomasses could be an efficient sorbent for REEs. Particularly, Ulva pertusa is found to be a promising biosorbent for removing La. (4)Ion-exchange process is considered to be the main mechanism responsible for the sorption of lanthanide ion onto the seaweed biomass.
