State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry , Chinese Academy of Sciences , Guangzhou 510640 , China.
University of Chinese Academy of Science , Beijing 100049 , China.
Environ Sci Technol. 2019 Jul 2;53(13):7683-7693. doi: 10.1021/acs.est.9b01788. Epub 2019 Jun 20.
The effects of the chemical structure, surface properties, and micropore of modified black carbon samples (BCs) on the sorption mechanism of hydrophobic organic contaminants (HOCs) are discussed. Activated and oxidized BCs were produced from a shale kerogen at 250-500 °C by chemical activation regents (KOH and ZnCl) and then by oxidative regents (HO and NaClO). The surface properties (water contact angel, Boehm titration, and cation exchange capacity, CEC), structural properties (advanced solid-state C NMR), micropore properties (CO adsorption), mesopore properties (N adsorption), and sorption and desorption properties of phenanthrene were obtained. The results showed that ZnCl-activated BCs had higher basic surface groups, CEC values, aromatic carbon contents, micropore volumes, and adsorption volumes but exhibited lower acidic surface groups than the KOH-activated BCs did. Micropore modeling and sorption irreversibility indicated that the micropore filling was the main sorption mechanism of phenanthrene. In addition, ZnCl activated and NaClO oxidized BCs showed a nice regression equation between adsorption volumes and micropore volumes (CO- V) as follows: Q = 0.495 V + 6.28( R = 0.98, p < 0.001). Moreover, the contents of nonprotonated aromatic carbon, micropore volumes, and micropore sizes are the critical factors to micropore filling mechanism of phenanthrene on BCs. The size of fused aromatic rings was estimated from the recoupled H-C dipolar dephasing, and the BC structural models at temperatures ranging from 300 to 500 were proposed. This finding improves our understanding of the sorption mechanism of HOCs from the perspectives of chemical structure and micropore properties.
讨论了改性黑碳样品（BC）的化学结构、表面性质和微孔对疏水性有机污染物（HOCs）吸附机制的影响。通过化学活化剂（KOH 和 ZnCl）和氧化剂（HO 和 NaClO）在 250-500°C 下从页岩干酪根中制备了活化和氧化的 BC。获得了表面性质（水接触角、Boehm 滴定和阳离子交换容量，CEC）、结构性质（高级固态 C NMR）、微孔性质（CO 吸附）、中孔性质（N 吸附）和菲的吸附和解吸性质。结果表明，ZnCl 活化的 BC 具有更高的碱性表面基团、CEC 值、芳香碳含量、微孔体积和吸附体积，但酸性表面基团比 KOH 活化的 BC 少。微孔建模和吸附不可逆性表明，微孔填充是菲在 BC 上的主要吸附机制。此外，ZnCl 活化和 NaClO 氧化的 BC 显示出吸附体积和微孔体积（CO-V）之间的良好回归方程，如下所示：Q=0.495V+6.28（R=0.98，p<0.001）。此外，非质子化芳香碳含量、微孔体积和微孔尺寸是菲在 BC 上微孔填充机制的关键因素。从再耦合 H-C 偶极去相可以估计稠合芳环的大小，并提出了 300-500 温度范围内的 BC 结构模型。这一发现从化学结构和微孔性质的角度提高了我们对 HOCs 吸附机制的理解。
