Removal and recovery of lead using nonliving biomass of marine algae.

Batch equilibrium sorption experiments were used for screening for cost-effective marine algal biomass harvested from the Gulf of Persian. Biosorption of lead by eight brown, green and red marine algae was investigated. Biosorption of lead was rapidly occurred onto algal biosorbents and most of the sorbed metal was bound in <30 min of contact. Three species of brown algae, namely Sargassum hystrix, S. natans and Padina pavonia, removed lead most efficiently from aqueous solution, respectively. The applicability of the Langmuir and Freundlich models for the different biosorbents was tested. An increasing uptake of the metal by biosorbents with increasing pH was demonstrated. Desorption of the adsorbed lead on biosorbent was conducted by decreasing the pH values to lower than 1.0. Removal of lead from Sargassum biomass was successfully achieved by eluting with 0.1M HNO3 for 15 min and a high degree of metal recovery was observed (95%). For optimum operation in the subsequent metal uptake cycle, regeneration of the Sargassum biomass was efficiently performed by 0.1M CaCl2 for 15 min that was total and reversible. In repeated use of biomass experiment, the lead uptake capacity of Sargassum biomass was constantly retained (98%) and no significant biomass damage took place after 10 sorption-desorption cycles.