摘要
近年来,基于纳米零价铁(nano zero-valent iron,nZVI)的非均相Fenton氧化技术成为了抗生素废水研究领域的热点,但是nZVI易迁移和易团聚的缺点限制了其进一步应用.为了解决该问题,本文选择含氮有机物乙二胺四乙酸(EDTA)和三聚氰胺(MA)作为配体,含有机碳的醋酸亚铁作为铁源,采用机械球磨法-高温裂解相结合的方法制备了负载nZVI的铁碳材料,并以磺胺噻唑(sulfathiazole,STZ)为目标污染物,探讨了Fe@EDTA(醋酸亚铁@乙二胺四乙酸)和Fe@MA(醋酸亚铁@三聚氰胺)2种铁碳复合材料激发过氧化氢(H_(2)O_(2))的非均相Fenton催化体系(Fe@C-H_(2)O_(2)体系)的影响因素及其作用机制.结果表明:①Fe@EDTA材料中纳米铁粒子的直径约为4 nm,在碳层中均匀分布,这种结构使得其具有较强的催化能力,而Fe@MA材料中的nZVI则聚集成直径约为400 nm的大颗粒,被100 nm碳层包覆.②Fe@EDTA材料的最佳铁碳比(醋酸亚铁与有机配体的质量比)为2∶1,Fe@MA材料的最佳铁碳比为3∶1,2种铁碳复合材料的最佳试验条件均为初始pH=3、H_(2)O_(2)投加量25 mmol/L、铁碳复合材料投加量0.2 g/L、STZ初始浓度20 mg/L.在最优条件下,2种铁碳复合材料的Fe@C-H_(2)O_(2)体系均可在30 min内完全降解STZ.③STZ的降解以及羟基自由基(∙OH)的产生均符合伪一级动力学模型.④连续运行300 min后,Fe@EDTA-H_(2)O_(2)体系对STZ的降解率仍高达82%,而Fe@MA-H_(2)O_(2)体系对STZ的降解率约为48%.⑤基于∙OH猝灭试验,推测铁碳复合材料与H_(2)O_(2)的非均相Fenton催化体系的机理是nZVI诱导的非均相Fenton氧化,其中∙OH和超氧自由基(∙O_(2)^(−))在氧化降解有机污染物过程中起到关键作用.研究显示,nZVI颗粒粒径更小的Fe@EDTA材料具有更加优异的催化性能以及更好的重复利用性和稳定性,能够高效降解水中的STZ.
In recent years,heterogeneous Fenton oxidation technology based on nano zero-valent iron(nZVI)has become a hot topic in the field of antibiotic wastewater research,but the shortcomings of nZVI are easy migration and agglomeration,which limits its further application.In this paper,in order to solve this problem,nitrogen-containing organic compounds ethylenediamine tetraacetic acid(EDTA)and melamine(MA)were used as ligands,errous sulkoxylate containing organic carbon was used as iron source,the iron carbon materials supported with nZVI were prepared by the method which combines mechanical ball milling and high temperature cracking.Sulfathiazole(STZ)was used as target contaminant.The influencing factors and mechanism of heterogeneous Fenton catalytic system(Fe@C-H_(2)O_(2))in which H_(2)O_(2)is excited by two kinds of iron-carbon materials were investigated.,and the mechanism of reaction was explored.The results showed that:(1)The diameter of the nano-iron particles in the ferrous acetate@ethylenediamine tetraacetic acid(Fe@EDTA)material was about 4 nm,and the density was evenly distributed in the carbon layer,which gave the material a strong catalytic ability.The nZVI in the ferrous acetate@melamine(Fe@MA)material aggregated into large particles with a diameter of about 400 nm and was coated by a 30 nm carbon layer.(2)The optimal iron-to-carbon ratio(mass ratio of ferrous acetate to organic ligand)of Fe@EDTA materials is 2∶1,the optimal iron-to-carbon ratio of Fe@MA materials is 3∶1,the optimal initial pH is 3,the optimal initial H_(2)O_(2)concentration is 25 mmol/L,the optimal catalyst dosing amount is 0.2 g/L,the optimal pollutant concentration is 20 mg/L.Under the optimal conditions,the two Fe@C-H_(2)O_(2)system of two kinds of iron-carbon composites can completely degrade STZ within 30 min.(3)The degradation of STZ and the generation of hydroxyl radicals(∙OH)fit the pseudo-primary kinetic model.(4)After 300 min of continuous operation,the degradation rate of STZ Fe@EDTA and hydrogen peroxide system(Fe@EDTA-H_(2)O_(2))is still as high as 82%,while the STZ degradation rate of Fe@MA and hydrogen peroxide system(Fe@MA-H_(2)O_(2))is only about 48%.(5)Based on the quenching experiment of free radicals,it is speculated that the mechanism is the Fenton-like oxidation induced by nZVI,and hydroxyl radicals(∙OH)and superoxide radicals(∙O_(2)^(−))play a key role in the oxidative degradation of organic pollutants.Studies have shown that Fe@EDTA materials with smaller particle size of nZVI particles have better catalytic properties and better reusability and stability,which can efficiently degrade STZ in water.
作者
权衡
牛琳
时迪
汪霞
梁为纲
赵晓丽
QUAN Heng;NIU Lin;SHI Di;WANG Xia;LIANG Weigang;ZHAO Xiaoli(State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China;School of Environment,Tsinghua University,Beijing 100084,China)
出处
《环境科学研究》
CAS
CSCD
北大核心
2022年第12期2732-2747,共16页
Research of Environmental Sciences
基金
广东省科学院专项资金项目(No.2020GDASYL-20200101002)。
