Design Experiments for Biosorption of Lead Ions from Wastewater by Box-Wilson’s Method

Abstract

Box-Wilson’s method of design of experiments was used to maximize heavy metal removal from synthetic wastewater. The process of optimization was based on four independent pertinent parameters: agitation speed (150-250) rpm, initial metal concentration (20-40) mg/l, pH (4-8), and biomass dose (2-4) g/l. Lead was chosen as heavy metal. A maximum biosorption was practically attained following thirty runs of different experiments, as given by 24 - Central Composite Design (CCD). The best conditions were initial metal concentration 25.29 mg/l, pH 5.78, biomass dose 3.36 g/l, agitation speed 209.21 rpm. The gained data of experiments were used to form a semiempirical model, based upon a quadratic polynomial, to foretell lead ions biosorption. The model was examined using a statistical software (Design Expert® 11.0) and found adequate. Biosorption response surfaces and contour plots were generated using the developed model, which exposed the existence of high biosorption plateaus whose specifications will be beneficial in monitoring industrial scale or pilot-scale units of future to confirm economic achievability.