State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, People's Republic of China.
School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, People's Republic of China.
Environ Sci Pollut Res Int. 2019 Jun;26(18):18636-18650. doi: 10.1007/s11356-019-05181-3. Epub 2019 May 4.
Biochar is being examined as a potential sorbent for organic pollutants in the environment including phthalate esters (PAEs). It has been noted that nano-scale biochar particles displayed stronger migration potential than other particles, which poses the potential risk of pollutant transfer through the environment. In this present study, we examined the influence of sub-millimeter (200-600 μm), micron-scale (10-60 μm), and nano-scale (0.1-0.6 μm) biochar on diethyl phthalate (DEP, as a model) adsorption using particles derived from corn straw and rice husk biochar. Meanwhile, the interaction between adsorption capacity and initial pH was also considered. Our results showed that the adsorption capacity of biochar for DEP increased with decreasing particle size, and was considerably higher for nano-scale biochar than for other particles. This was attributable to its developed pore structure and higher specific surface area (SSA), especially the dominant micropore (292.73 m/g), suggesting that the adsorption of DEP to nano-scale biochar was dominated by pore-filling rather than π-π EDA and H bonding that was applied to biochar of larger, more typical dimensions. The adsorption capacity of nano-scale biochar for DEP was markedly decreased when initial pH was decreased from 9.0 to 3.0. Because an acid environment could reduce the absolute surface charge on nano-scale biochar, it was easier for the particles to agglomerate. Nano-scale biochar therefore have higher activity in alkaline conditions, which could pose certain risks through their application into the environment.
生物炭被视为环境中有机污染物（包括邻苯二甲酸酯（PAEs））的潜在吸附剂。已经注意到，纳米级生物炭颗粒比其他颗粒表现出更强的迁移潜力，这可能会导致污染物通过环境转移的潜在风险。在本研究中，我们考察了亚毫米级（200-600μm）、微米级（10-60μm）和纳米级（0.1-0.6μm）生物炭对邻苯二甲酸二乙酯（DEP，作为模型）吸附的影响，使用玉米秸秆和稻壳生物炭衍生的颗粒。同时，还考虑了吸附容量与初始 pH 值之间的相互作用。研究结果表明，生物炭对 DEP 的吸附容量随粒径的减小而增加，纳米级生物炭的吸附容量明显高于其他颗粒。这归因于其发达的孔结构和更高的比表面积（SSA），特别是占主导地位的微孔（292.73 m/g），表明 DEP 对纳米级生物炭的吸附主要是通过孔填充而不是π-π EDA 和 H 键合来实现的，而这些作用通常适用于更大、更典型尺寸的生物炭。当初始 pH 值从 9.0 降低到 3.0 时，纳米级生物炭对 DEP 的吸附容量显著降低。因为酸性环境会降低纳米级生物炭的绝对表面电荷，所以颗粒更容易团聚。因此，纳米级生物炭在碱性条件下具有更高的活性，这可能会通过将其应用于环境而带来一定的风险。
