活性炭纤维负载硫化纳米零价铁用于活化PMS降解三氯苯酚

针对纳米零价铁(nanoscale zero-valent iron，nZVI)在反应过程中易团聚、易钝化和难回收等问题，采用比表面积大、化学稳定性好的活性炭纤维(activated carbon fibers，ACFs)作为载体，以连二亚硫酸钠(Na₂S₂O₄)作为硫化试剂，制备活性炭纤维负载硫化纳米零价铁复合材料(activated carbon fibers supported sulfidized nanoscale zero-valent iron，ACFs-S-nZVI)，并考察了复合材料活化过一硫酸盐(peroxymonosulfate，PMS)降解三氯苯酚(trichlorophenol，TCP)的催化性能、反应机理及重复使用性能。材料表征结果表明，硫化不仅可以缓解nZVI的氧化，还可以加快nZVI的电子传输速率，而引入ACFs载体则极大地提高了硫化纳米零价铁(sulfidized nanoscale zero-valent iron，S-nZVI)的分散性和稳定性。通过条件探究实验发现，当反应条件设置为S/Fe比0.3、温度25 ℃、pH=6、催化剂投加量0.5 g·L⁻¹、PMS投加量0.5 mmol·L⁻¹时，ACFs-S-nZVI/PMS体系表现出最佳的催化性能，在30 min内即可去除99.14% 10 μmol·L⁻¹的TCP，显著优于未改性的样品。此外，该体系具有较宽的pH(2~10)适应范围、优异的抗离子干扰能力以及出色的重复使用性能。电子顺磁共振波谱(EPR)和自由基淬灭实验结果表明，羟基自由基(^•OH)、硫酸根自由基(SO₄^•−)和超氧自由基(O₂^•−)参与了ACFs-S-nZVI/PMS体系的催化反应。综上可知，ACFs-S-nZVI具有催化性能优异、稳定性高、环境适应性强等优点，在催化降解有机污染物方面表现出较好的应用前景。

Degradation of trichlorophenol by activated carbon fibers-supported S-nZVI activating PMS

In order to cope with the problems of severe agglomeration, easy passivation and difficult recovery of nanoscale zero-valent iron (nZVI) during reaction process, the activated carbon fibers (ACFs) with large specific surface area and excellent chemical stability were taken as carriers, and sodium dithionite (Na2S2O4) was taken as the sulfidation reagent to successfully fabricate activated carbon fibers-supported sulfidized nanoscale zero-valent iron composite (ACFs-S-nZVI). Subsequently, the catalytic performance, reaction mechanism and recycling performance of this composite catalyst on trichlorophenol (TCP) degradation by activating peroxymonosulfate (PMS) were further investigated. The results of material characterization showed that the deposited ferrous sulfide (FeS) during the vulcanization process could not only mitigate the oxidation of nZVI, but also accelerate the electron transfer rate of nZVI, and the introduction of ACFs carrier substantially improved the dispersion and stability of sulfidized nanoscale zero-valent iron (S-nZVI). Through operational condition experiments, it was found that the ACFs-S-nZVI/PMS system exhibited the best catalytic performance when the reaction conditions were set to S/Fe ratio of 0.3, 25 ℃, pH of 6, catalyst dosage of 0.5 g·L−1 and PMS dosage of 0.5 mmol·L−1, and 99.14% of TCP with a concentration of 10 μmol·L−1 could be degraded within 30 min, which was significantly better than that of the unmodified sample. In addition, the system had a wide pH adaptation range (pH=2~10), an excellent anti-ion interference ability and an outstanding recycling performance. The electron paramagnetic resonance (EPR) spectroscopy and radical quenching experiments showed that hydroxyl radical (•OH), sulfate radical (SO4•−) and superoxide radical (O2•−) participated in the catalytic reaction of ACFs-S-nZVI/PMS system. In summary, ACFs-S-nZVI has the advantages of excellent catalytic performance, high stability, and strong environmental adaptability. Therefore, it shows great application prospects in catalytic degradation of organic pollutants.