Multi-metal biosorption in a fixed-bed flow-through column

Metal-biosorbent biomass of Sargassum fluitans brown seaweed biomass is capable of effectively removing toxic heavy metals from aqueous solutions. Involvement of physico-chemical mechanisms including biosorption, precipitation and microbial reductive processes has been established to play important roles in metal immobilization. Biosorption of Cu2+, Zn2+ and Cd2+ by S. fluitans biomass pre-loaded with Ca2+ is based on ion exchange mechanism accompanied by a release of Ca2+ into the solution phase. Carboxylic, sulfonate and phosphonate moieties of the biomass were quantitatively established as being responsible for the sequestering of heavy metals. Equilibrium biosorption ion exchange isotherms for Cu2+, Zn2+ and Cd2+ were determined. Metal biosorption dynamics in a fixed-bed flow-through sorption column was eventually predicted by numerically solving the equations of the ion exchange model proposed. This mathematical model, serving as a basis for sorption process computer simulations, takes into account also the mass transfer process. Computer simulation and prediction of the biosorbent behavior was carried out for sorption systems containing one, two, and multiple metal ionic species. The simulation offers a new and responsive tool for design and meaningful optimization of the metal recovery/removal processes. (c) 2006 Elsevier B.V. All rights reserved.