| 张萌,吕耀斌,朱一滔,罗雅琪,李威,李萍萍,王喜龙.生物炭去灰分对萘和1-萘酚的吸附动力学影响[J].农业环境科学学报,2020,39(12):2806-2814. |
| 生物炭去灰分对萘和1-萘酚的吸附动力学影响 |
| Effect of deashing treatment on sorption kinetics of naphthalene and 1-naphthol on wheat straw-derived biochar |
| 投稿时间：2020-06-23 |
| DOI：10.11654/jaes.2020-0708 |
| 中文关键词: 生物炭 有机污染物 去灰分 吸附动力学 双室模型 |
| 英文关键词: biochar organic pollutants deashing sorption kinetics two-compartment model |
| 基金项目:国家自然科学基金项目（41701555，31700441）；中国博士后科学基金面上项目（2020M671507） |
| 作者 | 单位 | | 张萌 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 吕耀斌 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 朱一滔 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 罗雅琪 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 李威 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 李萍萍 | 南京林业大学南方现代林业协同创新中心, 生物与环境学院, 南京 210037 | | 王喜龙 | 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871 |
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| 中文摘要: |
| 为探究生物炭矿物组分对有机污染物吸附过程的影响机制，考察（非）极性有机污染物萘和1-萘酚在不同温度（300、400、500℃）下制得的小麦秸秆原始生物炭以及去灰分后生物炭上的吸附动力学。结果表明：拟二级和双室一级动力学模型能较精确地描述目标污染物的动力学吸附过程。去灰分处理增加生物炭芳香碳含量，增强其与萘和1-萘酚间的p-p和疏水作用；同时降低生物炭表面极性，特别是减少表面烷氧基官能团的分布，提高疏水碳吸附域（主要是芳香碳）的可达性，导致平衡吸附量（Qe）增大。除灰后极性官能团在生物炭表面的暴露减少，促进萘分子向表面疏水吸附位点扩散，使得萘在生物炭上快吸附单元的吸附速率常数（kfast）升高；而极性1-萘酚结构中的—OH能通过氢键与生物炭表面极性官能团或矿物含氧表面相互作用，对快吸附有重要贡献，去灰分削弱氢键，造成其kfast下降。致密的芳香碳组分和纳米级孔隙结构主要对萘和1-萘酚在生物炭上的慢吸附起作用，去灰分提高生物炭芳香化程度和孔隙度，使慢吸附对总吸附的贡献（kslow）增大；同时使得化合物分子较难扩散进入更致密的生物炭内部。另外表面积和孔隙度的增大延长吸附平衡时间，两种化合物的慢吸附速率常数（kslow）均降低。研究表明，生物炭的矿物组分、化学组成和极性官能团的空间分布显著影响有机污染物的动力学吸附过程，从而影响生物炭在有机污染控制中的吸附性能。 |
| 英文摘要: |
| To elucidate the mineral effects of biochars on the sorption of organic pollutants(OPs), we investigated the sorption kinetics of naphthalene and 1-naphthol on both pristine and deashed wheat straw-derived biochars obtained at different temperatures. The kinetics data better fitted with the pseudo second-order model, followed by the two-compartment model in comparison with the pseudo first-order model. Deashing treatment increased the aromatic carbon content of biochars, thereby enhancing their p-p and hydrophobic interactions with the two tested compounds. Deashing also reduced the surface polarity of biochars, especially the O-alkyl polar components, thereby enhancing the accessibility of their hydrophobic carbon domains, mainly the aromatic carbon components. Hence, the equilibrium sorption capacity(Qe)of naphthalene and 1-naphthol increased. Reducing the external exposure of polar functional groups by mineral removal enhanced the diffusion of naphthalene molecules toward the hydrophobic sorption sites, thereby increasing its sorption rate constant for the fast-sorbing fraction on biochars(kfast). However, the substituted polar -OH group in 1-naphthol was able to interact with polar groups on biochars or mineral O-containing surfaces via H-bond that greatly contributed to its fast sorption. The H-bonding was weakened after deashing, which could account for a higher kfast value of 1-naphthol by the original biochar than that of its corresponding deashed one. Deashing increased the amount of aromatic components and porous structures in biochars, which were responsible for the slow sorption of naphthalene and 1-naphthol, resulting in increased contributions of the slowly sorbing fraction to the total sorption(kslow). The increased condensation of organic carbon in deashed biochars hindered the diffusion of naphthalene and 1-naphthol molecules into biochars. Additionally, increasing the surface area and porosity of biochars prolonged the sorption equilibrium time, and thus the rate constants for the slow sorption fraction(kslow)of both compounds decreased. The results of this work could help us better understand the effect of minerals, chemical composition, and spatial arrangement of polar functionalities of biochars on the sorption of OPs and predict their fate in soils after biochar application. |
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