摘要
将苯酚选择性转化为高附加值的化学品对苯醌(p-BQ)是目前污染物资源化转化研究的焦点之一.与具有强氧化性的羟基自由基和硫酸根自由基相比,高价铁物种(Fe^(Ⅳ)=O和Fe^(Ⅴ)=O)与单线态氧(^(1)O_(2))氧化能力适中,可以选择性将污染物定向转化为高附加值的下游中间体,从而实现资源化利用.因此,本文报道了一种有效的电化学策略,通过热聚合法制备单原子铁负载的氧掺杂石墨相氮化碳(Fe-OCN)阴极材料,电催化活化过一硫酸盐(PMS)产生高价铁物种和单线氧,选择性氧化苯酚为高附加值的醌类产物.研究结果表明,通过优化铁掺杂量、电流强度、苯酚浓度和反应时间等条件,可以实现苯酚到对苯醌的高效转化:苯酚的转化率在70 min内达到了91.93%,苯醌的选择性和收率分别为69.21%和63.63%.Fe-OCN阴极材料在较宽的pH的范围(3~7)和多种无机离子的干扰下依旧能保持较高的性能,并且在处理含酚焦化废水的实际应用中也具有较好的效果,为实现酚类废水高附加值资源化利用提供了一个新的思路.
Phenol pollutants,as a kind of high concentration and high toxicity organic pollutants commonly found in wastewater,have various degrees of harm to human health and the ecological environment.Compared with direct degradation,the selective conversion of phenol into p-benzoquinone,which is more than ten times more valuable than phenol,is more cost-effective and in line with the call for sustainable development and energy recycling.Electrocatalytic oxidation technology has been widely used for the deep treatment of phenolic organic pollutants in sewage wastewater.Still,the selective electrocatalytic conversion of phenols to high-value-added chemicals has rarely been reported,because in the conventional electrochemical oxidation technology,the oxidation process is mainly mediated by hydroxyl radicals.However,advanced oxidation techniques dominated by free radicals such as hydroxyl radicals are susceptible to the influence of water background(e.g.,natural organic matter,inorganic salt ions,etc.)in practical applications,resulting in excessive consumption of chemicals and energy.The non-radical pathways of high-valent iron oxidation,singlet oxygen oxidation,and electron transfer processes are highly resistant to interference,highly selective for some pollutants,and widely applicable,and have been used in studies of phenol coupling or polymerization and the resourceful conversion of phenol to benzoquinone.In this study,monatomic Fe-loaded oxygen-doped graphitic phase carbon nitride(Fe-OCN)cathode materials were prepared by thermal polymerization for the selective oxidation of phenol to benzoquinone via electrocatalytic activation of persulfate(PMS)to produce high-valent iron species and singlet oxygen.The optimal material Fe-OCN-03 obtained by optimizing the Fe loading achieved 91.93%conversion of phenol,and 69.21%and 63.63%selectivity and yield of benzoquinone,respectively.Analysis of the results of quenching and electron paramagnetic resonance(EPR)experiments indicated that the OCN-00/PMS electrocatalytic system produced singlet oxygen as the main active species.In contrast,the FeOCN-03/PMS system after introducing monatomic Fe generated singlet oxygen and high-valent iron as the two main oxidatively active species involved in the phenol resourcing process.The involvement of high-valent iron reactive species was instrumental in improving the selectivity of the conversion of phenol to p-benzoquinone.These active species offered a more controlled and targeted oxidation pathway,which minimized the formation of unwanted by-products and ensured preferential conversion of phenol molecules to the desired product p-benzoquinone.Notably,this system involved no generation of free radical oxidation reactive species,which was favorable for controlling the selectivity of the reaction.In addition,the Fe-OCN-03/PMS electrocatalytic system exhibited excellent catalytic performance in the pH(3–7)range,indicating its adaptability under different environmental conditions.Also,the system exhibited strong resistance to a wide range of inorganic ions,which is an essential advantage for practical application in a complex wastewater matrix.This system also showed excellent stability,which maintained a relatively good performance over multiple catalytic cycles,thus highlighting its potential for long-term use.In real coking wastewater,the Fe-OCN-03/PMS electrocatalytic system achieved efficient and selective conversion of phenol to p-benzoquinone under realistic conditions.It enhanced its applicability as a robust electrocatalyst for resource-oriented pollutant transformation.Compared with other works,the Fe-OCN-03/PMS electrocatalytic system showed a relatively high removal rate of phenol with less time required,which has the potential for application and space for improvement.The results of this research provided a theoretical and experimental basis for the rational design and optimization of electrocatalytic materials for the resource-oriented conversion of phenol to benzoquinone.
作者
宋炎锴
陈敏
韦宇韬
冯智渊
赵红颖
Yankai Song;Min Chen;Yutao Wei;Zhiyuan Feng;Hongying Zhao(School of Chemical Science and Engineering,Tongji University,Shanghai 200092,China)
出处
《科学通报》
北大核心
2025年第14期2085-2094,共10页
Chinese Science Bulletin
基金
国家自然科学基金(22122606,22076142)
上海市科学技术委员会(14DZ2261100)
中央高校基本科研业务费专项资金资助。
关键词
单原子铁
PMS活化
高价铁
苯酚
资源化转化
single-atom iron
peroxymonosulfate activation
high-valent iron
phenol
resource conversion
