Adosorption behaviors of metal in leaching solution of phosphors using biosorption by microalgae

Aiming development of the recovery process of rare earth elements from waste phosphors by biosorption, microalgae Actodesmus acuminatus was used as biosorbent for rare earths elements. Europium and yttrium were leached from a commercially available light-emitting diode (LED) 3-wave form phosphor by strong acid solution. Adsorption of europium was inhibited when aluminum and calcium coexisted at a higher concentration than europium. Living algal cells as adsorbents have a complex adsorption mechanism of chemisorption on cell surface. Further, the inactivated cells by autoclave treatment or ultraviolet treatment lost a part of adsorption mechanism, and decreased adsotion amount of yttrium. However, The decrease of adsorption amount of aluminum and gallium was limited. Europium leached from phosphors by citric acid. However, it was difficult to separate europium from leaching solution by biosorption because metal complex adsorped on only cell surface.