Optimisation of Adsorption Removal of Bisphenol A Using Sludge-Based Activated Carbons: Application of Response Surface Methodology with a Box–Behnken Design

The potential use of sewage sludge as a precursor for the production of activated carbon was explored in this paper. After chemical activation with ZnCl2, three activated carbons were used to decontaminate synthetic solutions containing Bisphenol A and the results were compared with a commercial activated carbon. The effect of the impregnation ratio (activating agent/precursor) and the use of CO2 during the second carbonisation on the textural properties and Bisphenol A adsorption performance of the activated carbons were studied. The highest specific surface area achieved was 730 m2/g, obtained with an impregnation ratio of 2:1 with the use of CO2.The kinetics of Bisphenol A adsorption were successfully described by both pseudo-second-order and Elovich models, while the adsorption isotherms were well fitted to the Freundlich model. The prepared activated carbon had excellent adsorption efficiency toward Bisphenol A with a maximum adsorption of 285.8 mg/g which was closer to the retention amount of the commercial one. The best adsorption conditions for Bisphenol A removal were obtained by applying response surface methodology (RSM) coupled with Box-Behnken design (BBD) onto AC-Industrial2. Under these conditions, 657.76 mg/g can be reached. Thus, these optimum conditions were therefore applied for bisphenol A removal from real effluents and the obtained results are very promising.