Three-Dimensional Hierarchical Porous Carbon with High Oxygen Content from Bitumite Mixed with Waste Powder Char for Excellent Wastewater Purification

Abstract

Abstract Waste powder char (WPC) is harmful to the environment and is abundant in the production process of the coal chemical industry, which will produce relatively low heat energy and release large amounts of coal ash if it is burned directly. To efficiently solve this issue and create high values, three-dimensional hierarchical porous carbons (HPCs) with abundant oxygen-containing groups were prepared by collaborative pyrolysis carbonization and steam activation from Yulin bitumite (YL) mixed with WPC. The effects of preparation parameters including WPC doping amount, activation temperature, and activation time on pore structure development and adsorption capacity of methylene blue from wastewater were explored in detail. The obtained HPCs are micropores structure combined with mesopores and the largest specific surface area (SSA) is reached to 1299.75 m2g− 1 (8-YLHPC-950-3). Furthermore, 8-YLHPC-900-3 presents a high oxygen content reaches 15.92wt%. And the SSA and total pore volume of HPC with an 8wt% WPC doping ratio are larger than that without WPC doping. Meanwhile, HPCs show the superior adsorption performance of methylene blue in aqueous solution, especially when the HPC was prepared at the activation temperature of 900 ℃, steam flow of 0.8 mLg− 1h− 1, and activation time of 3 h. It presents the optimal adsorption capacity that is 301 mgg− 1 of methylene blue adsorption value (MBV). We conclude a value-added utilization approach for coal based solid waste and a potential feedstock for adsorption material used in the purification of wastewater. The results achieved in this study provide a green and environmentally friendly method for the preparation of HPCs from waste powder char which is not only an industrial reference for the removal of methylene blue from wastewater by HPCs but also contributes to the sustainable development of the coal chemical industry.