Cr(VI)和酚类化合物之间的不同物理化学性质对有效处理共污染提出了严峻的挑战。本研究开发了一种无电极高流量微波大气等离子射流,用于单步同时降解对硝基苯酚(PNP)和还原Cr(VI)。用微波大气压等离子体处理15分钟后,Cr(VI)和PNP的去除率分别达到97.5%和93.6%,分别,而占总有机碳的30.2%。溶液中加入PNP显著提高了Cr(VI)的还原性,而PNP降解随Cr(VI)的增加而略有增加。结果表明,PNP中间体显著影响Cr(VI)还原。此外,长寿命H2O2和短寿命·H有助于等离子体处理期间Cr(VI)的还原。在处理过程中添加羟基清除剂意味着·OH是PNP氧化的主要原因。高效液相色谱-质谱(HPLC-MS)显示PNP中间体,包括对硝基儿茶酚和5-硝基苯-1,2,3-三醇,作为Cr(VI)还原剂。根据所检查的中间产品,研究了潜在的PNP降解途径。可能影响同时降解和还原的因素,包括溶液pH值,气体速度,研究了等离子体出口与水面之间的距离。低pH支持Cr(VI)还原,PNP对Cr(VI)还原的促进作用适用于所有pH值。在有或没有Cr(VI)的情况下,PNP的降解对pH值不敏感。PNP降解和Cr(VI)还原的最佳气体速度为6L/min。PNP和Cr(VI)的同时去除得益于等离子体出口和水表面之间的较短距离。
Different physicochemical properties between Cr(VI) and phenolic compounds pose serious challenges for the effective treatment of co-contamination. This study developed an electrodeless high-flow microwave atmospheric plasma jet for the single-step simultaneous degradation of p-nitrophenol (PNP) and reduction of Cr(VI). Following a 15 min treatment with microwave atmospheric pressure plasma, the removal efficiency of Cr(VI) and PNP reached 97.5% and 93.6%, respectively, whereas that of total organic carbon reached 30.2%. Adding PNP to the solution significantly improved Cr(VI) reduction, whereas PNP degradation increased slightly with Cr(VI). The results indicate that the PNP intermediates significantly affected Cr(VI) reduction. Additionally, long-lived H2O2 and short-lived ·H aided the reduction of Cr(VI) during plasma treatment. The addition of hydroxyl scavengers during treatment implied that ·OH was largely responsible for PNP oxidation. High-performance liquid chromatography-mass spectroscopy (HPLC-MS) revealed that PNP intermediates, including p-nitrocatechol and 5-nitrobenzene-1,2,3-triol, function as Cr(VI) reductants. On the basis of the examined intermediate products, the potential PNP degradation pathway was investigated. The factors that could influence simultaneous dehgradation and reduction, including solution pH, gas velocity, and distance between the plasma outlet and the water surface were researched. Low pH supports Cr(VI) reduction, and the promotion of PNP for Cr(VI) reduction applies to all pH values. The degradation of PNP is insensitive to pH values with or without Cr(VI). The optimal gas velocity for PNP degradation and Cr(VI) reduction was revealed to be 6 L/min. The simultaneous removal of PNP and Cr(VI) benefits from a shorter distance between the plasma outlet and the water\'s surface.