Engineered biochar with ultrahigh surface areas derived from postpyrolysis with urea for efficient removal of plasticizer

Highly developed porous materials are urgently needed for the efficient remediation of contaminated environments. However, their preparation methods are extremely limited, and new production processes have always been a research focus. In this study, a green and efficient sequential carbonization method was proposed to prepare excellent porous biochar from bamboo waste; the sequential steps were hydrothermal carbonization, potassium/calcium formate-assisted prepyrolysis, and urea-assisted postpyrolysis. The specific surface area reached 3921 m2/g, which is much greater than that of reported porous materials, and the pore volume reached 1.87 cm3 g−1. Moreover, the nitrogen content was as high as 2.04 %. The developed nitrogen-doped porous biochars (NPBs) were applied to the sorption of a typical plasticizer, diethyl phthalate, from water. The surface sorption quantity dominated the entire sorption capacity. The maximum sorption amount was 823.46 mg g−1. Pore filling, partitioning, hydrogen bonding and π-π stacking are possible sorption mechanisms. In addition, the stable properties of NPBs have great potential for recycling. This work has developed a high-value, green method to prepare excellent porous materials with great promise for the sorption of pollutants and could be further applied in the fields of catalysis, energy storage, and filtration.