Optimization of aquatic Cu(II) removal within a competitive metal ion sorption against Cd(II) and Pb(II) on low-cost biomass of artichoke

Abstract

Cu(II), Pb(II) and Cd(II) are the most abundant heavy metal ions found in industrial wastewaters.This research on the removal of metal ions from water streams is commissioned by QUIMYTEC and focusses on the optimization of the competitive aquatic Cu(II) sorption against Cd(II) and Pb(II) on low-cost biomass of artichokes. Based on Taguchi's OA design methodology, the influence of pH, initial metal concentration and biomass dosage on the sorption mechanism was evaluated. These parameters were selected from the system and parameter design after preliminary study and subsequently tested at 3 different levels in a 25 °C isothermally performed batch experiment for 24 h. Furthermore, the sorption capacity was introduced as the performance characteristic to be maximized in the Taguchi analysis. Subsequently, the process capacities were calculated from ICP-OES responses of the analysed batch sequence and lastly evaluated by the MiniTab software. From the analysis, it appears that the initial Cu(II) and Pb(II) concentration exert the most import main effects, whilst two-factor interactions between Cu-Cd and Cu-Pb appear to be non-existing. A maximum Cu(II) sorption capacity of 6.77 mg/g was obtained by adding 0.5 g/L biomass and adjusting the pH to 5 in an ionic solution which contained 50 mg/L of Cu(II) and 10 mg/L of Cd(II) and Pb(II). Based on these settings, a kinetic experiment was conducted in order to modulate the evolution towards equilibrium by Langmuir, Freundlich and Temkin isotherm, of which the first one fits best.