Adsorption of lead(II) by silica/cell composites from aqueous solution: kinetic, equilibrium, and thermodynamics studies.

Silica/cell composites were prepared for the adsorption of lead ions, Pb(II), from aqueous solution in a batch system. The silica/cell composites possessed micropores, high surface area, and abundant functional groups. Adsorption performance was investigated by analyzing the effects of such factors as the initial pH, contact time with different initial concentration, and initial Pb(II) concentration at different temperature. The kinetic data were fitted to pseudo-second-order and intraparticle diffusion kinetic models. The results were better fitted by the pseudo-second-order kinetic model. Intraparticle diffusion increased with an increase of initial concentration and the sorption process was controlled by film diffusion. The Langmuir isotherm model was fitted to the experimental data significantly better than Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacity was 97.10 mg g(-1), according to the Langmuir isotherm model. Thermodynamics parameters confirmed the spontaneous, endothermic, and entropy-gained nature within the studied temperature range (from 298 to 318 K). The composites could be effectively desorbed by the 2.0 mol L(-1) HNO3 solution and would be a potential adsorbent.

Biosorption of Pb(II) by biomass of KC-2: kinetic, equilibrium and characteristic studies.

Performance and characteristics of biosorption of Pb(II) had been studied in a batch system using the fungal strain biomass, KC-2. The biosorption performance was investigated by analysing the effects of such factors as the initial pH, initial Pb(II) concentration, and contact time at 303 K. The maximum Pb(II) adsorption was obtained at pH 5.0. The experimental data were described by the pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models, and were closely followed the pseudo second-order kinetic model. The equilibrium experimental data were well fitted to Langmuir model and the maximum biosorption capacity was 84.03 mg g(-1). The adsorption mechanism was examined by FTIR, SEM and EDAX analysis. Results indicated that carboxylic, hydroxyl and amine groups were involved in the biosorption and ion exchange mechanism existed.