基于苝酰亚胺超分子的新型光自芬顿体系高效降解苯酚的效能与机理

Highly-efficient phenol degradation by a novel perylene diimide supermoleculebased photo-self-fenton system and mechanism investigation

将芬顿反应与光催化体系相结合构建的光自芬顿协同体系,无需外部添加过氧化氢即可展现出十分优异的氧化降解污染物能力。采用羧酸侧链型苝酰亚胺超分子(PDI-C)与Fe3+相结合的PDI-C/Fe3+光自芬顿体系,获得了极高效且持久的苯酚(含酚废水的模型污染物)降解率。通过系统探究催化反应中铁物种形态与含量的变化,双氧水的产生机制与含量变化以及各活性物种的含量变化等,揭示了PDI-C/Fe3+体系协同降解苯酚的催化过程机理。Fe3+通过与PDI-C超分子羧酸侧链位点的相互作用,一方面发挥其电子捕获的作用,接受光生电子转变为Fe^(2+),并大幅促进了体系光生载流子的分离;另一方面,光催化过程原位生成的双氧水,与光催化介导的有效循环的铁离子对,形成了光自芬顿体系,进而协同促进了苯酚的高效、持久降解。研究还发现,随着反应的进行,于PDI-C表面生成的α-FeOOH造成的铁损耗及其对PDI-C表面吸光位点的遮蔽,是催化活性降低不可忽略的因素;而加酸不仅可抑制α-FeOOH等的生成,还可将已生成的α-FeOOH溶出并使其再参与铁离子对的有效循环,进而协同促进了光自芬顿体系的高效运转。同时,还揭示了此体系中光催化自产双氧水的2种途径及其主次要关系,并揭示了在Fe3+存在下,羟基自由基和超氧自由基的生成存在竞争关系。基于此,所构建的PDI-C/Fe3+光自芬顿体系,不仅展现出可见光辐照下对苯酚污染物高效、持久的降解性能,且其成本低廉、操作简单,应用潜力巨大。

The photo-self-Fenton collaborative system,which combines Fenton reaction with photocatalytic system,exhibits excellent oxidation ability over pollutants without external addition of hydrogen peroxide.Herein,the PDI-C/Fe3+photoself-Fenton system,combining carboxylic acid side chain modified perylene diimide supramolecule(PDI-C)and Fe3+,is used to obtain an extremely efficient and durable degradation efficiency of Phenol(a model pollutant in phenolic wastewater).The research systematically investigates the catalytic reaction mechanism by examining the changes in the form and content of iron species,the production mechanism and content changes of hydrogen peroxide and the content changes of various active species.The interaction between Fe3+and the carboxylic acid side chain of PDI-C promotes photo-gener-ated electron capture by Fe3+and the resultant conversion to Fe^(2+),accordingly facilitating the separation of photogener-ated carriers.On the other hand,the hydrogen peroxide generated in-situ during the photocatalytic process pairs with the effective circulation of iron ions to form a photo-self-Fenton system,which synergically promotes the efficient and dur-able phenol degradation.It is also found that as the reaction prolonged,α-FeOOH formed on the surface of PDI-C not only results in iron loss,but also leads to the obscuration of light-absorbing sites,thus becoming a non-negligible factor for the decrease of catalytic activity.Notably,acid addition can not only inhibit the generation ofα-FeOOH,but also aid the leaching of formedα-FeOOH,enabling an efficient iron ion circulation and the photo-self-Fenton system's efficient opera-tion.The work also identifies two pathways of hydrogen peroxide production and reveals a competitive relationship between·OH and·O2-in the presence of Fe3+.These findings highlight the high efficiency and durability of the PDI-C/Fe3+photo-self-Fenton system in degrading phenol pollutants under visible light irradiation,while showcasing its poten-tial for practical applications due to its cost-effectiveness and simplicity.