Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 51006, China.
Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 51006, China.
J Hazard Mater. 2021 Mar 5;405:124684. doi: 10.1016/j.jhazmat.2020.124684. Epub 2020 Nov 26.
Carbon-catalyzed persulfate activation for the removal of gaseous volatile organic compounds (VOCs) has not been reported yet, and the corresponding fundamental mechanisms of VOCs adsorption and the subsequent VOCs degradation remain controversial. In this work, theoretical chemistry calculations were carried out to explore the VOCs removal mechanism by the persulfate-based advanced oxidation processes (P-AOPs) for VOCs removal over single walled carbon nanotubes (SWCNT). This study provided detailed theoretical insights into the SWCNT/P-AOPs for VOCs treatment in terms of adsorption, activation, mineralization, and diffusion of VOCs or peroxymonosulfate (PMS). Various VOCs were found to be preferentially adsorbed onto SWCNT, and the adsorption strength of VOCs was found to be significantly dependent on their polarizability. On the other side, PMS adsorbed on SWCNT could be efficiently activated through accepting π electron in the sp carbon matrix of SWCNT rather than the electrons at dangling bonds to generate •OH radicals attributed to the strong interaction between PMS and SWCNT. Formaldehyde was then taken as an example to evaluate the catalytic degradation pathways via SWCNT/P-AOPs. Under the attack of •OH radicals, the ultrafast degradation pathway of formaldehyde with no byproduct CO was identified with ultralow reaction energy barrier and large energy release. In addition, factors affecting the adsorption of organic compounds were identified and the detailed PMS activation pathway was present directly in this work. Above all, this work extended the carbons/P-AOPs system to VOCs abatement and presented systematic evidences for the essential mechanisms associated with VOCs adsorption and PMS activation by SWCNT, and the corresponding removal pathway and mechanism were also understood.
碳催化过硫酸盐活化去除气态挥发性有机化合物（VOCs）尚未见报道，而相应的 VOCs 吸附和随后的 VOCs 降解的基本机制仍存在争议。在这项工作中，通过理论化学计算，研究了在单壁碳纳米管（SWCNT）上通过过硫酸盐基高级氧化工艺（P-AOPs）去除 VOCs 的机制。本研究从吸附、活化、矿化以及 VOCs 或过一硫酸盐（PMS）的扩散等方面，为 SWCNT/P-AOPs 处理 VOCs 提供了详细的理论见解。研究发现，各种 VOCs 优先被吸附到 SWCNT 上，VOCs 的吸附强度与它们的极化率显著相关。另一方面，PMS 吸附在 SWCNT 上可以通过接受 SWCNT 中 sp 碳基质中的π电子而不是悬键处的电子来有效地活化，这归因于 PMS 和 SWCNT 之间的强相互作用。然后，以甲醛为例评估通过 SWCNT/P-AOPs 的催化降解途径。在 •OH 自由基的攻击下，确定了无副产物 CO 的甲醛超快速降解途径，其反应能垒超低，能量释放大。此外，还确定了影响有机化合物吸附的因素，并在本工作中直接呈现了详细的 PMS 活化途径。总之，这项工作将碳/P-AOPs 系统扩展到 VOCs 减排，并为 SWCNT 吸附和 PMS 活化的基本机制提供了系统的证据，同时还理解了相应的去除途径和机制。
