Bamboo-Derived Low-Cost Mesoporous Biochar for Efficient Removal of Per- and Polyfluoroalkyl Substances from Contaminated Water

Adsorption by activated carbon (AC) is a practical approach to removing per- and polyfluoroalkyl substances (PFAS) from water, but designing a highly efficient carbon for the adsorption of target PFAS using a low-cost strategy remains a challenge. Herein, we report that bamboo-biochar prepared by vacuum carbonization and steam activation serves as an alternative adsorbent to commercial AC for PFAS removal. The optimal biochar (V500A) exhibited an adsorption capacity of 1.23 and 0.77 mmol/g for perfluorooctanesulfonate and 6:2 fluorotelomer sulfonate (6:2 FTS), respectively, which outperforms the previously reported biochar, and the adsorption rate was 2.4 times higher than that of the commercial AC F400. An excellent adsorption performance by V500A in electroplating wastewater and drinking water demonstrates its versatile applicability. Pore reaming played a major role in the adsorption enhancement, and the hydrophobic and electrostatic interactions were mainly responsible for PFAS adsorption. In addition, pyrolysis regeneration at a mild temperature (500 °C) can effectively reactivate spent biochar. The results of this study are expected to provide a feasible pore-designing approach to achieving the preparation of cost-effective biochar-based adsorbents for PFAS removal from contaminated water.