Fabrication of novel Fe/Mn/N co-doped biochar and its enhanced adsorption for bisphenol a based on π–π electron donor–acceptor interaction

In this work, a novel Fe/Mn/N co-doped biochar (Fe&Mn-NBC800) derived from waste apple tree branches was fabricated for bisphenol A (BPA) removal. Fe&Mn-NBC800 exhibited higher adsorption capacity (84.96 mg·g-1) in 318 K for BPA than the pristine biochar, doped mono-atomic, and di-atomic biochar. Higher temperature and adsorbent dosage promoted BPA removal, while higher solution pH was detrimental to the adsorption process. The kinetic and isothermal processes of BPA removal followed the pseudo-second-order model and Langmuir, respectively. Characterizations and correlation analysis indicated that π-π interactions showed the major contribution to the BPA adsorption. Furthermore, the pore filling, electrostatic interactions, hydrogen bonding, and hydrophobic interactions also played a role. Good water environment anti-interference ability (ion species, ionic strength, actual water body) and excellent recyclability of Fe&Mn-NBC800 make it exhibit the potential for engineering projects.