Regeneration and reuse of a seaweed-based biosorbent in single and multi-metal systems

A seaweed-waste material resulting from the processing of Ascophyllum nodosum was previously shown to be very efficient at removing Zn(II), Ni(II) and Al(III) both in single and multi-metal waste streams. In this study, the regeneration of the biosorbent using an acid wash resulted in the release of high metal concentrations during multiple desorption cycles. Maximum desorption efficiencies (DE) of 183, 122 and 91% were achieved for Zn(II), Ni(II) and Al(III), respectively, for subsequent metal loading cycles, significantly exceeding the desorption rates observed for conventional sorbents. The regeneration of the sorbent was accomplished with very little loss in metal removal efficiency (RE) for both single and multi-metal systems. Values of 92, 96 and 94% RE were achieved for Zn(II), Ni(II) and Al(III), respectively, for the 5th sorption cycle in single metal aqueous solutions. A slight decrease was observed for the same metals in multi-metal systems with maximum REs of 85, 82 and 82% for Zn(II), Ni(II) and Al(III), respectively. This study showed that the novel sorbent derived from a seaweed industrial waste would be suitable for multiple metal sorption cycles without any significant loss in RE.