Fabrication of modified-N-doped porous biochar and its enhanced adsorption of bisphenol-A: critical contribution to π–π interactions by nitrogen doping

A novel nitrogen-doped porous biochar (NS@LBC800) was prepared for bisphenol A (BPA) removal using waste loofah as raw materials, NaHCO3 as the activator, and urea as a nitrogen source. Pre-experiments confirmed the optimal preparation conditions. At 318 K, the adsorbed amount was 308.42 mg g−1. Higher temperatures and adsorbent dosage promoted adsorption. The pseudo-second-order model and Langmuir, respectively, described kinetic and isothermal processes well. Characterization and theory calculation showed that the efficient adsorption was attributed to its superb pore structure and N-atom doping. Among the numerous adsorption driving forces, the most important were the pore-filling effect and π-π interactions. Also, the contribution of hydrogen bonding and hydrophobic interactions was unable to be ignored. NS@LBC800 had good universality and recyclability. The results may provide theoretical guidance for nitrogen-doped biochar preparation and BPA removal.