Mechanism of Pb2+ removal from aqueous solution using a nonliving moss biomass

Biosorption of lead (II) ions onto raw biomass of the moss plant Barbula lambarenensis has been studied using the batch equilibrium adsorption method. Equilibrium isotherms, kinetics and thermodynamic parameters have been evaluated. The FT-IR analysis showed that likely functional groups responsible for the adsorption are carboxyl, carbonyl, amides and hydroxyl groups. The pH for optimum adsorption is 5.0. Equilibrium data fit well to the Langmuir isotherm. The estimated maximum adsorption capacity was found to be 62.50 mg/g at 298 K and 90.91 mg/g at 323 K. The kinetic data obeyed the pseudo-second-order model. The free energy changes (Delta G degrees) are positive and the reaction is exothermic with decreased randomness at the sorbent/solution interface. Taking into account its good adsorption capacity, ease of sample treatment, as well as availability, the biomass of B. lambarenensis is a promising cost-effective biosorbent for Pb2+ removal from aqueous environment. (c) 2012 Elsevier B.V. All rights reserved.