The removal of Cu(II) from dilute aqueous solutions by Saccharomyces cerevisiae

Abstract

Biosorption of Cu(II) by virgin or treated unicellular yeast, Saccharomyces cerevisiae, was studied. Cu(II) adsorption is strongly affected by pH. A given amount of protein is released from live cells upon interactions with metal ions. This decreases the amount of Cu(II) uptake and is most pronounced at high pH values. Adsorption takes place on multisites and can be analyzed by Scatchard plots. Cu(II) uptake by live yeast was biphasic and consisted of an initial, rapid surface binding of Cu(II) followed by a second, slower intracellular uptake of Cu(II). Cu(II) uptake by dead yeast and Cd(II), Pb(II) uptake by live yeast takes place only via surface binding. In a total of 30 μmol/g Cu(II) uptake by live yeast, 7 μmol/g can be attributed to the intracellular uptake. A sand column with immobilized S. cerevisiae can completely remove metals before the breakpoint. After the breakpoint, a significant amount of Cu(II) removal over a long period was observed. This is thought to be the result of intracellular uptake. Strong acid can be used to strip the Cu(II)-laden column for reuse. The result shows that a Cu(II)-laden column can be stripped of adsorbed Cu(II) with one volume of acid (5 × 10 −3 M HClO 4) per 20 volumes of Cu(II) containing solution.