Biosorption of lead from aqueous solution onto Nasturtium officinale: performance and modeling

Nasturtium officinale powder (NoP), with leached active ingredients, was used here to adsorb lead (Pb), as a water pollutant. The effects of several variables on the removal of lead including initial pH, contact time, adsorbent dosage and initial concentration of lead were studied. The response surface plots were used for estimating the interactive effects of variables. The statistical analysis and modeling by response surface methodology and central composite design are demonstrated to be effective and reliable in finding the optimal conditions for the adsorption of lead onto NoP. The results showed that the biosorption conditions have significant effects on the removal of lead, and 10 g L –1 of NoP had the best adsorption efficiency. The equilibrium data was analyzed using Langmuir and Freundlich isotherms models. The pseudo-second-order kinetics model best explained the Pb biosorption by NoP of any dosage.