N-doping effectively enhances the adsorption capacity of biochar for heavy metal ions from aqueous solution

作者：Yu, Wenchao; Lian, Fei^*; Cui, Guannan; Liu, Zhongqi

来源：Chemosphere, 2018, 193: 8-16.

DOI：10.1016/j.chemosphere.2017.10.134

• N-doping
• Biochar
• Heavy metal
• Adsorption mechanism

N-doping was successfully employed to improve the adsorption capacity of biochar (BC) for Cu2+ and Cd by direct annealing of crop straws in NH3. The surface N content of BC increased more than 20 times by N-doping; meanwhile the content of oxidized-N was gradually diminished but graphitic-N was formed and increased with increasing annealing temperature and duration time. After N-doping, a high graphitic-N percentage (46.4%) and S-BET (418.7 m(2)/g) can be achieved for BC. As a result, the N-doped BC exhibited an excellent adsorption capacity for Cu2+ (1.63 mmol g(-1)) and Cd2+ (1.76 mmol g(-1)), which was up to 4.0 times higher than that of the original BC. Furthermore, the adsorption performance of the N-doped BC remained stable even at acidic conditions. A positive correlation can be found between adsorption capacity with the graphitic N content on BC surface. The surface chemistry of N-doped BC before and after the heavy metal ions adsorption was carefully examined by XPS and FFIR techniques, which indicated that the adsorption mechanisms mainly included cation-pi bonding and complexation with graphitic-N and hydroxyl groups of carbon surfaces.

• 出版日期2018-2
• 单位南开大学; 中国农业科学院