Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan 523808, China.
School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
Sci Total Environ. 2021 Feb 25;757:143719. doi: 10.1016/j.scitotenv.2020.143719. Epub 2020 Nov 14.
This work presented a three-dimensional (3D) hierarchically microporous biochar (HMB) via molten alkali treatment that achieved efficient adsorption of perfluorinated carboxylic acids (PFCAs), which was a significant environment concern due to the global distribution and potential health risks. The systematic optimization of fabrication process rendered the HMB large surface area and uniform microporous structure, leading to a high adsorption capacity and adsorption rate of 1269 mg/g and 197 mg/(g·min), respectively, when perfluorooctanoic acid (PFOA) was as a representative. The adsorption mechanisms were explored via controlling the interaction between PFCAs and the HMB900-2.4. Specifically, hydrophobic effect was verified by the enhanced adsorption performance with the increase of the PFCAs homologues hydrophobicity. The observed highly pH-dependent adsorption capacity additionally suggested the dominant contribution of electrostatic interaction. For long-chain PFCAs (CFCOOH, n > 5), the HMB900-2.4 presented a high removal efficiency (> 90%) within 30 min. Even for short-chain PFCAs (CFCOOH, n = 4-5), the removal efficiency reached to over 60%. The synthesized HMB900-2.4 exhibited high stability during recycling experiments and superior performance over commercial adsorbents, suggested a promise of utilizing it to remove PFCAs from wastewater.
这项工作通过熔融碱处理制备了一种三维（3D）分级微孔生物炭（HMB），实现了全氟羧酸（PFCAs）的有效吸附。由于其在全球范围内的分布和潜在的健康风险，PFCAs 是一个重要的环境关注点。通过系统优化制备工艺，使 HMB 具有较大的比表面积和均匀的微孔结构，从而使 1000mg/L 的全氟辛烷酸（PFOA）的吸附量和吸附速率分别达到 1269mg/g 和 197mg/（g·min）。通过控制 PFCAs 与 HMB900-2.4 之间的相互作用，探讨了吸附机制。具体而言，通过增加 PFCAs 同系物疏水性来增强吸附性能，验证了疏水作用的存在。观察到的高度依赖于 pH 值的吸附容量进一步表明静电相互作用的主导贡献。对于长链 PFCAs（CFCOOH，n>5），在 30min 内，HMB900-2.4 对其具有很高的去除效率（>90%）。即使对于短链 PFCAs（CFCOOH，n=4-5），去除效率也达到 60%以上。在回收实验中，合成的 HMB900-2.4 表现出较高的稳定性，并且其性能优于商业吸附剂，这表明它有望用于从废水中去除 PFCAs。
