Porous N-doped carbon converted from protein-rich shrub enables record-high removal of p-nitrophenol: superior performance and mechanism

The complete removal of harmful phenolic contaminants from water remains huge challenge because of the lack of cost-effective and powerful adsorbents. Herein, a sustainable nitrogen self-doped biochar (named KBC750N) with large specific surface area (1398.44 m2/g), high adsorption capacity (606.06 mg/ g) and removal ratio (99.99%) for p-nitrophenol (PNP) in real waters (Seawater, Yangtze River water, and Yellow River water) was prepared from a naturally abundant protein-rich psammophyte Caragana kor-shinskii (CK) by a facile one-step pyrolysis process. The in-situ nitrogen-doped biochar shows much better adsorption removal efficiency of 99.99% toward PNP than expensive commercial adsorbents (only 77.52%). The biochar still keeps high adsorption efficiency after reused more than five times. Site energy distribution analysis revealed that the biochar captures PNP mainly through n -p and p -p electron -donor-acceptor interactions among the electron-rich functional groups (N-containing moieties,-COOH, and-OH), graphite carbon, and PNP. Density functional theory (DFT) calculations confirmed that the nitrogen site in biochar helps to strengthen its adsorption capability to PNP. This work provides a sus-tainable platform for the development of high-performance, cost-effective materials for efficient elimi-nation of organic pollutants from water.& COPY; 2023 Elsevier Ltd. All rights reserved.