Experimental and robust modeling approach for lead(II) uptake by alginate gel beads: Inlfuence of the ionic strength and medium composition

Systematic kinetic and equilibrium studies on the lead ions removal ability by Ca-alginate gel beads havebeen performed by varying several internal parameters, namely, number of gel beads, nature and compositionof the ionic medium and pH, which allowed us to model a wastewater in order to closely reproduce the composition of a real sample. Moreover, the effects brought about the different ionic speciespresent in the reacting medium have been evaluated.Differential Pulse Anodic Stripping Voltammetry (DP-ASV), has been systematically used to performkinetic and equilibrium measurements over continuous time in a wide range of concentration. Kineticand equilibrium data have been quantitatively analyzed by means of robust approach both for thenon-linear regression and the subsequent residuals analysis in order to significantly improve the resultsin terms of precision and accuracy.Alginate gel beads have been characterized by SEM and an investigation on their swelling behavior has also been made. Removal efficiency of the calcium-alginate gel beads has been calculated and resultsobtained have showed a relevant dependence on ionic strength, composition of ionic media, pH of solution and number of gel beads. The number of gel beads takes part as key crucial components, i.e., the higher the number of beads the greater the amount of Pb(II) species removed from the sample, the lower the time needed to reach the maximum removal efficiency of 90%.