Simultaneous bio-sorption of heavy metals by marine sea-weeds

The aim of this work is to investigate the heavy-metals uptake properties of a dried biomass coming from plant (green algae and leaves of marine macro-phytes) pick up on the shore of a polluted wetland. Bio-sorption has been carried out taking into consideration a solution containing metal nitrates (10 mg/l of Cd, Zn, Pb, Cu and Ni + 1 mg/l of Hg in distilled water) with initial pH values between 5 and 9. Experimental results has shown that, in a batch system (solutionibiomass = 1/1 in weight) fast metal sorption occurs. Total metal-uptake capacity of the biomass was of 0.54 mMol/g dry weight. Hg has been used as indicator of total metal uptake. After contact for 15 minutes (pH = 5divided by7) about 70 % of initial Hg has been extracted. Regeneration of the biomass after sorption has been considered for reuse: a HCl solution has been adopted starting from different initial pH. It has been pointed out that regeneration by HCl leaching occurs in a proper and effective way at a pH value at least two points lower than that the sorption pH. Regenerating with HCl solution at pH = 2 allows de-sorption of more than 30% of sorbed metals.