Isotherm and kinetic study on Ni(II) and Pb(II) biosorption by the fern Asplenium nidus L.

The extent of biosorption of Pb(II) and Ni(II) by dried leaves of the fern Asplenium nidus depends on experimental conditions, such as initial pH, initial concentration, contact time and shaking speed. Kinetic data were fitted to pseudo first order, pseudo second order, intraparticle diffusion and Elovich models. Isotherm data were fitted to two-parameter and three-parameter isotherm models. A. nidus adsorbed 58% of Ni(II) and 95% of Pb(II) after 30 min and 75 min, respectively, under the experimental conditions provided. The protonated biosorbent adsorbed 75% of Ni(II) after 30 min. Kinetic data fitted the pseudo second order model and the intraparticle diffusion model showed that intraparticle diffusion is not the only process that governs the adsorption process. Isotherm studies showed that Langmuir-Freundlich isotherm model explains the adsorption process well.