• 关键词：富氮生物炭  重金属  氮构型  作用机制

• 基金项目：国家自然科学基金（No.41773107）；广东省基础与应用基础研究基金项目（No.2020A1515011560）；广州市科技计划项目（No.202002030297）

• 江钰
• 华南理工大学环境与能源学院, 广州 510006

• 邓郁蓉
• 华南理工大学环境与能源学院, 广州 510006

• 王金灵
• 华南理工大学环境与能源学院, 广州 510006

• 杨琛
• 1. 华南理工大学环境与能源学院, 广州 510006;2. 工业聚集区污染控制与生态修复教育部重点实验室, 广州 510006

• 黄伟林
• 1. 华南理工大学环境与能源学院, 广州 510006;2. 罗格斯大学环境科学系, 新泽西州 08901

• 党志
• 1. 华南理工大学环境与能源学院, 广州 510006;2. 工业聚集区污染控制与生态修复教育部重点实验室, 广州 510006

• 摘要：为了明确不同构型富氮生物炭对重金属的作用机理，本研究以玉米秸秆为生物质，通过尿素改性结合高温热解制备了3种不同氮构型的富氮生物炭（以吡咯氮为主的Pr-NBC、吡啶氮为主的Pd-NBC和石墨氮为主的Gp-NBC），考察其对典型重金属的作用行为.吸附动力学和吸附等温线等实验结果显示：富氮生物炭对Pb （II）和Cr （VI）的吸附均以化学吸附为主，且存在明显的差异；对Pb （II）的吸附容量与溶液离子强度成正比，吸附可能以形成内层络合物为主，对Cr （VI）的作用则包含吸附和还原两个过程；对两种重金属的吸附容量受pH影响较大，静电吸引作用可能是主要驱动力.吸附前后的材料表征显示：富氮生物炭主要通过静电吸引作用、阳离子交换、沉淀作用和阳离子-π键作用吸附Pb （II），通过静电吸引作用吸附Cr （VI），同时能将Cr （VI）还原为Cr （III）.不同构型氮与重金属作用机理存在差异，其中，石墨氮主要通过与Pb （II）形成阳离子-π键作用促进吸附，吡咯氮和吡啶氮具有还原性，可将Cr （VI）转化为Cr （III），实现减毒.因此，在考察自然环境中富氮生物炭对重金属的作用机制时，应当充分考虑氮构型的影响.

• Abstract：In order to clarify the contributions of different nitrogen species of nitrogen-rich biochars in their adsorption for heavy metals, three nitrogen-rich biochars with different nitrogen configurations (Pr-NBC with pyrrolic nitrogen, Pd-NBC with pyridinic nitrogen and Gp-NBC with graphitic nitrogen) were prepared by pyrolysing corn straw with urea. Results of adsorption kinetics and adsorption isotherms showed that the adsorption of Pb(II) and Cr(VI) by nitrogen-rich biochars were dominated by chemical adsorption. The adsorption capacity for Pb(II) was directly proportional to the ionic strength of the solution, which indicated that the adsorption may be dominated by the formation of inner complexes. Cr(VI) can be removed by nitrogen-rich biochars through adsorption and reduction. The adsorption capacity for heavy metals was greatly affected by pH, revealed that electrostatic attraction may be the main driving force. Characterization of materials before and after adsorption showed that nitrogen-rich biochars mainly removed Pb(II) through electrostatic attraction, cation exchange, precipitation and cation-π bond interaction, while Cr(VI) was adsorbed by electrostatic attraction and partially reduced to Cr(III). The roles of different nitrogen species on the adsorption were quite different. Specifically, graphitic nitrogen mainly promoted adsorption by forming cation-π bond with Pb(II). Pyrrolic nitrogen and pyridinic nitrogen reduced Cr(VI) into Cr(III) to achieve attenuation. To assess the interaction between nitrogen-rich biochars and heavy metals in the environment accurately, the influences of nitrogen configurations should be fully considered.

• Key words：nitrogen-rich biochars  heavy metals  nitrogen configurations  mechanism of action

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