Multiple biosorption–desorption cycles in a fixed-bed column for Pb(II) removal by acid-treated olive stone

Biosorption of Pb2+ from aqueous solutions and desorption of Pb2+ from acid-treated olive stone were studied. Equilibrium screening tests of lead desorption established a solution of 0.3 M hydrochloric acid as the most appropriate eluting agent. Fixed-bed biosorption and desorption recovery curves for Pb2+ were obtained for multiple consecutive biosorption–desorption cycles and the biosorption properties of the biomass for Pb2+ were compared after each cycle to evaluate the stability of the biomass. The biosorbent retained most of its original uptake capacity over fourteen cycles of use. Life factor calculation revealed that biosorbent bed would be completely exhausted after 71.3 cycles.