REUTILIZATION OF NONVIABLE BIOMASS OF PHORMIDIUM-LAMINOSUM FOR METAL BIOSORPTION

The capability to biosorb Cu(II), Fe(II), Ni(II) and Zn(II) by non-via ble biomass of the cyanobacterium Phormidium laminosum, from single an d binary metal solutions, was examined. The biosorption process was ex tremely rapid and consisted of a single phase, The presence of a secon d metal in solution decreased the binding of Fe(II), Ni(II) and Zn(II) but had no effect on the binding of Cu(II). Chemical blocking of carb oxy groups of biomass resulted in a decrease in its metal-binding capa bility, The biosorbed heavy metals could be desorbed by washing the bi omass with diluted acids but not with NaOH, NaCl, CaCl2 or ultrapure w ater. Metal desorption was rapid, reaching completion in 30 min, its e fficiency being independent of the desorbent concentration above 0.1 M . Desorption of biosorbed metal with 0.1 M HCl allowed the reuse of th e biosorbent for at least five consecutive biosorption/desorption cycl es without an apparent decrease in its metal biosorption capability.