Adsorption Performance of Hollow Spherical Sludge Carbon Prepared from Sewage Sludge and Polystyrene Foam Wastes

Although sludge carbons have been widely studied, no attention has been paid to the preparation and application of hollow sludge carbon. In this study, innovative hollow spherical sludge carbons (HSCs) were prepared by pyrolyzing polystyrene foam sphere @sludge. The precursors, including sewage sludge and polystyrene foam, are solid wastes and produced in large volumes around the world. By this method, HSCs with a tunable shell thickness from 02 to 2.5 mm were obtained. The batch and column experiments show that the adsorption capacity and rate of HSCs for methylene blue increase with the decrease of the shell thickness, e.g., HSC with 02 mm thickness exhibits the highest adsorption capability of 149 mg(-1) and intraparticle diffusion rate constant of 21.5 mg g(-1) h(-0.5), 2.2 and 3.8 times larger than that of solid sludge carbon, respectively. In addition, two modification methods were proposed to further enhance the adsorption performance of HSCs. Finally, HSCs can be easily recycled and efficiently regenerated by thermal treatment These results demonstrate that HSCs with thin shell thickness is a promising adsorbent for wastewater treatment and the production of HSCs is a sustainable strategy for beneficial use of sewage sludge and PS foam wastes.