Experimental Optimization of Lead (II) Bioadsorption from Aqueous Solution onto Banana Stalk using Central Composite Design

Abstract

This study investigated the effect of operating parameters on the bioadsorption process of Pb(II) from its aqueous solution using three Banana Stalk (BS) bioadsorbents [Raw (RBS), Acid Activated (AABS) and Base Activated (BABS) ]. A five-factor, three-level Central Composite Design (CCD) was applied to determine the effects of independent variables (initial metal concentration, contact time, temperature, adsorbent dosage and solution pH) on percentage Pb(II) removal. Response Surface Methodology (RSM) was employed to optimize the parameters in the experiment. AABS had the highest percentage removal (96.13%) from the preliminary experiment and was then used for the optimisation experiment. Data analysis showed that all the variables significantly affected the percentage Pb(II) removal at p < 0.05. The square of the adjusted coefficient of determination for regression model of percentage Pb(II) removal is 0.9355. Optimum percentage removal of 96.41% was obtained using AABS when the Pb(II) concentration, contact time, temperature, dosage and solution pH were 21.83g/mL, 152.21minutes, 50^oC, 0.90g and 8.00,  respectively. There absolute error between the experimental and the predicted optimum percentage removal was less than 1%.

Keywords: Banana stalk, optimization, bioadsorption, acid, base.