Aquatic Invasive Plant Biomass-Derived Magnetic Porous Biochar Prepared by Sequential Carbonization and Coprecipitation for Diethyl Phthalate Removal from Water

Low-cost multifunctional sorbents are urgently needed, especially for the treatment of emerging pollutants that are widely distributed in various water environments. This work transformed an aquatic invasive plant, Pistia stratotes, into magnetic porous biochars (P-MPBs) based on a proposed strategy involving sequential carbonization to increase porosity and subsequent coprecipitation with ferric salts. Both the porous structure (specific surface area of up to 996.86 m2/g) and high Fe3O4 loading (saturation magnetization of up to 23.48 emu/g) were maintained. A typical plasticizer, diethyl phthalate (DEP), was selected as a model emerging organic pollutant, and the sorption quantity of the P-MPBs reached 490.04 mg g-1, which is much higher than that of many reported sorbents, especially magnetic sorbents. P-MPBs can be reused multiple times due to their excellent separation characteristics and stable structure. On the basis of kinetics and isotherm analysis, multilayer sorption, including pore filling, hydrogen bonding, pi-pi stacking, and partitioning, was the main DEP sorption process for the P-MPBs. Our study suggested that the proposed method could be promising and inspiring for the transformation of biowaste into excellent magnetic porous biochar that is recyclable and highly efficient at removing pollutants in water.