【作者】 张建；

【导师】 张永丽；

【作者基本信息】 四川大学 ， 土木工程， 2023， 博士

【摘要】 双酚AF（BPAF）等内分泌干扰物对人类健康和动植物生长存在严重的危害,当前在江、河、湖等各类环境水体中均有检出,特别是国内一些环境水体（如珠江、东江等）中BPAF检出浓度相对较高。因此,寻找适宜的方法去除水体中BPAF等内分泌干扰物是控制水中新污染物的重要任务。高级氧化技术已被验证是一种有效的降解水中难降解有机污染物的处理技术,部分技术已经进入工程应用阶段,而基于过硫酸盐的高级氧化技术由于其良好的去除效率、温和的反应条件、二次污染小等优势受到广泛关注。因此开发稳定性强、催化活性高的催化材料活化过硫酸盐是具有重要研究意义的课题。本研究以Mn₃O₄活化过硫酸盐降解BPAF的机制研究为基础,逐步探索制备了Mn_0.2Co_0.8O_x、Mn₃O₄@BiOI、Co₃O₄@BiOI三种新型复合催化剂,并对其活化过硫酸盐降解BPAF的效能与机制进行了深入的研究。主要开展的工作包括以下方面:（1）本论文以Mn₃O₄作为催化剂,通过BPAF降解实验评价了其活化过一硫酸盐（PMS）的性能。实验证明,Mn₃O₄可以有效活化PMS降解水中BPAF,其最佳实验条件为BPAF=5 mg/L、PMS=4.0 mM、Mn₃O₄=500 mg/L、初始pH=7.2。在上述条件下,Mn₃O₄/PMS体系中BPAF去除率大于90.0%。此外,多种共存无机阴离子对体系中BPAF降解过程的影响具有显著差异。当反应体系中加入Cl^-时,BPAF的降解效率明显提高,而体系中存在的HCO₃^-和NO₃^-均会对BPAF的降解产生抑制作用。同时,分析催化剂使用寿命的循环试验表明Mn₃O₄具有较好的重复利用性能;Mn₃O₄粉末的SEM、XRD、FT-IR表征分析结果显示反应前后材料变化较小,表明材料具有良好的稳定性。淬灭实验和电子顺磁共振（EPR）证明Mn₃O₄/PMS体系中主要活性氧物种（ROS）为硫酸根自由基(SO₄^·-)和羟基自由基（·OH）;同时基于淬灭实验结果和数据模拟计算方法,对系统中产生的^·OH和SO₄^·-相对贡献度进行了半定量分析。最后,在结合XPS分析和主要活性物质成分分析,提出了Mn₃O₄/PMS体系的主要催化活化机制是由于Mn（Ⅱ）与HSO₅^-反应,通过电子转移途径生成SO₄^·-,随后生成的SO₄^·-再与水分子反应,在溶液中生成·OH;与此同时,反应体系中生成的SO₄^·-和·OH快速氧化目标污染物（BPAF）生成其它转化产物,并最终将其矿化为CO₂和H₂O。（2）为进一步提高锰氧化催化活性,本论文通过制备锰钴双金属复合氧化物,深入分析其活化PMS降解BPAF的效能与机制。实验结果显示,当Mn的掺杂比为0.2时,Mn_0.2Co_0.8O_x催化活化PMS去除水中BPAF的效率最高,优于其他的掺杂材料(Mn_0.3Co_0.7O_x92.0%,Mn_0.4Co_0.6O_x89.2%,Mn_0.5Co_0.5O_x83.5%)。特别是当实验条件为BPAF=5 mg/L、PMS=0.2 mM、Mn_0.2Co_0.8O_x=400 mg/L、初始pH=7.2时,Mn_0.2Co_0.8O_x/PMS体系中BPAF去除率可达97.7%。同时采用SEM、EDS、XRD等表征手段对Mn_0.2Co_0.8O_x的结构特征分析显示,制备的Mn_0.2Co_0.8O_x催化剂为圆球状形貌且晶型良好。淬灭实验和EPR检测结果证明Mn_0.2Co_0.8O_x/PMS体系中主要活性氧物种（ROS）为SO₄^·-和·OH。基于XPS分析和活性物质分析结果,提出了反应体系中主要通过Co（Ⅲ）/Co（Ⅱ）和Mn（Ⅲ）/Mn（Ⅱ）的氧化还原对激活PMS产生SO₄^·-和·OH的反应机理。同时,催化剂外表面形成的O_Vs,参与并加速催化反应进程,促进活性物质的生成。（3）为了进一步探究锰氧化物的催化性能,本论文以BiOI为基底,通过一步水热合成法制备Mn₃O₄@BiOI复合催化剂,并系统性探究了该催化剂活化过二硫酸盐（PS）降解BPAF的效能与机制。通过对比分析,与Mn₃O₄/PMS、Mn_0.2Co_0.8O_x/PMS体系相比,Mn₃O₄@BiOI/PS体系具有更高的催化性能。同时实验对比分析了不同掺杂比例条件下合成的Mn₃O₄@BiOI复合材料的催化活性,发现当Mn₃O₄的掺杂比为50%时,50%Mn₃O₄@BiOI催化活化PS去除水中BPAF的效率最高,在无光照的情况下可达91.2%。实验还通过SEM、TEM、XRD、XPS、FT-IR等表征分析手段,详细分析了复合材料的形貌、组分、晶型、表面元素价态以及化合键能。通过自由基淬灭实验和EPR检测手段,分析了Mn₃O₄@BiOI/PS体系中产生的主要活性物质为硫酸根自由基(SO₄^·-)、羟基自由基（·OH）和超氧自由基（·O₂^-）以及非自由基单线态氧（¹O₂）。同时基于XPS表征分析,结合活性物质分析结果,提出了Mn₃O₄@BiOI/PS体系中,SO₄^·-、·OH、·O₂^-以及¹O₂四种活性氧物质协同作用促进BPAF的氧化分解,其中,SO₄^·-、·OH以及¹O₂对BPAF的有效去除发挥着重要的作用。催化进程中,主要是通过Mn（Ⅳ）/Mn（Ⅲ）/Mn（Ⅱ）、Bi（Ⅴ）/Bi（Ⅲ）氧化还原对激活PS产生活性物质,同时氧空位(O_Vs)也参与了反应进程,并对有机污染物的去除起到了重要的促进作用。（4）前一章研究了Mn₃O₄@BiOI/PS体系对水中难降解有机物BPAF的去除,虽然相较于Mn₃O₄/PMS、Mn_0.2Co_0.8O_x/PMS体系,Mn₃O₄@BiOI/PS体系表现出显著的降解去除能力,但过渡金属氧化物负载BiOI复合材料的催化性能仍有进一步提高的空间,并分析其中反应机理的区别。因此为进一步提升BPAF的去除率效率,探究基于BiOI复合材料的催化性能,本论文以BiOI为基底,通过一步水热合成法制备了Co₃O₄@BiOI复合材料。通过对比实验研究发现,相比于Mn₃O₄/PMS、Mn_0.2Co_0.8O_x/PMS、Mn₃O₄@BiOI/PS体系,Co₃O₄@BiOI/PS体系催化降解水中BPAF的效率最佳。重点分析了不同Co₃O₄负载量对复合催化剂活性的影响,并通过SEM、TEM、XRD、XPS、FT-IR表征分析,详细分析了Co₃O₄@BiOI复合材料的形貌、组分、晶型、表面元素价态以及化合键能,发现Co₃O₄颗粒均匀分布在具有花球空间结构的BiOI纳米片之间,形貌规则且晶型良好。随后,采用单因素控制法优化了催化剂用量、PS浓度、初始溶液pH等参数,其最佳工艺条件为:BPAF=5 mg/L,PS=0.2 mM,Co₃O₄@BiOI=200 mg/L,初始pH=5.8±0.2。此外,采用淬灭实验和EPR检测手段验证了Co₃O₄@BiOI/PS体系中存在的主要活性物种为SO₄^·-、·OH、·O₂^-以及¹O₂。系统的提出了复合材料对于PS的活化机理,其中主要包括Co（Ⅲ）/Co（Ⅱ）的氧化还原作用及Bi（Ⅲ）催化PS,以及Co₃O₄@BiOI两种单体之间的相互协同作用。同时,经过材料稳定性试验和环境实际水体试验,表明了复合材料Co₃O₄@BiOI在活化PS氧化体系中具有良好的重复利用稳定性。（5）为进一步研究BPAF在氧化过程中的变化规律,本文对比分析了体系中Mn₃O₄/PMS、Mn_0.2Co_0.8O_x/PMS、Mn₃O₄@BiOI/PS、Co₃O₄@BiOI/PS的BPAF矿化率,并以Mn₃O₄/PMS体系为重点分析了其反应过程中BPAF的矿化率变化和主要降解途径。结果表明,反应发生90 min后,BPAF的矿化率可达73.2%,高于本课题研究的其他体系。同时通过GC/MS、LC/MS检测手段和DFT模拟计算,对降解过程中的主要中间产物进行了详细的分析研究,最后提出了Mn₃O₄/PMS体系中BPAF的三种主要氧化降解途径。本研究以Mn₃O₄活化过硫酸盐降解BPAF的机制研究为基础,逐步探索制备了锰钴双金属氧化物复合材料(Mn_0.2Co_0.8O_x)以及锰、钴改性BiOI复合材料（Mn₃O₄@BiOI和Co₃O₄@BiOI）三种新型复合催化剂,并深入研究了其活化过硫酸盐降解BPAF的效能与机制。结果表明,以上几种材料对于水中特征污染物均具有优异的降解性能,拓展了基于硫酸根自由基高级氧化技术应用领域,为催化降解水中特征污染物提供了基础理论指导。更多还原

【Abstract】 This article discusses the serious harm caused by endocrine disruptors such as bisphenol A F（BPAF）to human health and the growth of animals and plants.BPAF has been detected in various environmental waters,and relatively high concentrations have been found in some water bodies in China,such as the Pearl River and the Dongjiang River.Therefore,seeking for suitable methods to remove BPAF and other endocrine disruptors from environmental waters is an important and urgent task in remediating emerging organic pollutants.Advanced oxidation technologies（AOTs）are a deries of effective methods for degrading refractory organic pollutants in water.Some AOTs have been used in practical engineering applications,and persulfate-based AOTs have been widely studied due to its good removal efficiency,mild reaction conditions,and low secondary pollution.Therefore,developing catalytic materials with high stability and high catalytic activity to activate persulfate is a research topic of significant importance.This study is based on the mechanism of Mn₃O₄activated peroxydisulfate to degrade BPAF and gradually explores the preparation of three new composite catalysts,including Mn_0.2Co_0.8O_x,Mn₃O₄@BiOI,and Co₃O₄@BiOI.The efficiency and mechanism of activating persulfate to degrade BPAF were deeply studied.The main work includes the following aspects:（1）In this paper,Mn₃O₄was used as a catalyst to evaluate its performance in activating peroxydisulfate（PMS）for the degradation of BPAF through experimental degradation.The results showed that Mn₃O₄can effectively activate PMS to degrade BPAF in water,and the optimal experimental conditions were BPAF=5 mg/L,PMS=4.0 mM,Mn₃O₄=500 mg/L,and initial pH=7.2.Under these conditions,the removal efficiency of BPAF in the Mn₃O₄/PMS system was greater than 90.0%.In addition,various coexisting inorganic anions exhibited significant differences on the degradation of BPAF in the Mn₃O₄/PMS system.The addition of Cl^-to the reaction system significantly improved the degradation efficiency of BPAF,while the presence of HCO₃^-and NO₃^-in the system inhibited the degradation of BPAF.The cyclic experiments on the catalyst’s lifespan showed that Mn₃O₄has good reusability for long-term operation.The SEM,XRD,and FT-IR characterization analysis results of Mn₃O₄powder before and after the reaction showed little change,indicating that the material has good stability.Quenching experiments and electron paramagnetic resonance（EPR）proved that the main reactive oxygen species（ROS）in the Mn₃O₄/PMS system were sulfate radicals(SO₄^·-)and hydroxyl radicals（·OH）.Based on the quenching experiments and simulation calculation,a semi-quantitative analysis was carried out on the relative contribution of·OH and SO₄^·-generated in the system.Finally,based on the analysis of XPS analysis and the main active substances,the main catalytic activation mechanism of the Mn₃O₄/PMS system was proposed,which is that Mn（Ⅱ）reacts with HSO₅^-to generate SO₄^·-through an electron transfer pathway,and then the generated SO₄^·-reacts with water molecules to generate·OH in the solution.At the same time,the generated SO₄^·-and·OH rapidly oxidize the BPAF to produce other transformation products and eventually mineralize them into CO₂and H₂O.（2）In order to further improve the catalytic activity of manganese oxide,this paper prepared manganese-cobalt bimetallic composite oxide and analyzed in depth its efficiency and mechanism in activating PMS to degrade BPAF.The experimental results showed that when the doping ratio of Mn was 0.2,Mn_0.2Co_0.8O_xhad the highest catalytic activity in activating PMS to remove BPAF from water,which was better than other doped materials(Mn_0.3Co_0.7O_x（92.0%）,Mn_0.4Co_0.6O_x（89.2%）,Mn_0.5Co_0.5O_x（83.5%）).Especially when the experimental conditions were BPAF=5mg/L,PMS=0.2 mM,Mn_0.2Co_0.8O_x=400 mg/L,and initial pH=7.2,the removal rate of BPAF in the Mn_0.2Co_0.8O_x/PMS system could reach 97.7%.The structural characteristics of Mn_0.2Co_0.8O_xwere analyzed by SEM,EDS,XRD and other characterization methods,which showed that the prepared Mn_0.2Co_0.8O_xcatalyst had a spherical shape and good crystal structure.Quenching experiments and EPR tests proved that the main reactive oxygen species（ROS）in the Mn_0.2Co_0.8O_x/PMS system were SO₄^·-and·OH.Based on XPS analysis and active substance analysis results,a reaction mechanism was proposed,which mainly involved the redox pairs of Co（Ⅲ）/Co（Ⅱ）and Mn（Ⅲ）/Mn（Ⅱ）to activate PMS to produce SO₄^·-and·OH.（3）To further explore the catalytic performance of manganese oxide,this paper used bismuth oxyiodide（BiOI）as a substrate to prepare Mn₃O₄@BiOI composite catalysts through a one-step hydrothermal synthesis method,and systematically investigated the efficacy and mechanism of this catalyst in activating PS to degrade BPAF.Through comparative analysis,Mn₃O₄@BiOI/PS system has higher catalytic performance than Mn₃O₄/PMS and Mn_0.2Co_0.8O_x/PMS systems.The catalytic activity of Mn₃O₄@BiOI composite materials synthesized under different doping ratios was also experimentally compared,and it was found that when the doping ratio of Mn₃O₄was 50%,the Mn₃O₄@BiOI catalyst had the highest efficiency in removing BPAF from water,reaching 91.2%without additional light irradiation.Characterization techniques such as SEM,TEM,XRD,FT-IR,and XPS were used to analyze the morphology,composition,crystal structure,chemical bond energy,and surface element valence state of the composite material in detail.Through free radical quenching experiments and EPR detection methods,it was found that the main active substances produced in the Mn₃O₄@BiOI/PS system were SO₄^·-,·OH,superoxide radical（·O₂^-）,and non-radical singlet oxygen（¹O₂）.Based on XPS characterization analysis and the analysis of active substances,it was proposed that SO₄^·-,·OH,·O₂^-,and ¹O₂in the Mn₃O₄@BiOI/PS system synergistically promote the oxidation decomposition of BPAF,among which SO₄^·-,·OH,and ¹O₂play important roles in effectively removing BPAF.During the catalytic process,the activation of PS to produce active substances was mainly achieved through the oxidation-reduction of Mn（Ⅲ）/Mn（Ⅱ）and Bi（Ⅴ）/Bi（Ⅲ）.（4）The previous chapter studied the removal of the organic pollutant BPAF in water by the Mn₃O₄@BiOI/PS system.Although the Mn₃O₄@BiOI/PS system showed a significant degradation and removal ability compared to the Mn₃O₄/PMS and Mn_0.2Co_0.8O_x/PMS systems,there is still room for further improvement in the performance of the BiOI-based transition metal oxide-loaded composite material.Therefore,to further enhance the removal efficiency of BPAF,this chapter investigated the catalytic performance based on the BiOI composite material,and synthesized the Co₃O₄@BiOI composite material using a one-step hydrothermal synthesis method with BiOI as the substrate.Comparative experiments showed that the Co₃O₄@BiOI/PS system had the best catalytic efficiency in degrading BPAF in water compared to the Mn₃O₄/PMS,Mn_0.2Co_0.8O_x/PMS,and Mn₃O₄@BiOI/PS systems.The effect of different Co₃O₄loading amounts on the activity of the composite catalyst was analyzed in detail,and the morphology,composition,crystal structure,surface element valence state,and bonding energy of the Co₃O₄@BiOI composite material were characterized by SEM,TEM,XRD,XPS,and FT-IR.The results showed that the Co₃O₄particles were evenly distributed between the BiOI nanosheets with a flower-like spatial structure,and the morphology was regular with a good crystal structure.Subsequently,single-factor control was used to optimize the catalyst dosage,PS concentration,initial solution pH,and other parameters.The optimal process conditions were as follows:BPAF=5 mg/L,PS=0.2 mM,Co₃O₄@BiOI=200 mg/L,initial pH=5.8±0.2,and reaction temperature of 25℃.In addition,the quenching experiment and EPR detection were used to demonstrate that the main active species in the Co₃O₄@BiOI/PS system were SO₄^·-,·OH,·O₂^-,and ¹O₂.The activation mechanism of the composite material for PS was proposed,which mainly included the redox reaction of Co（Ⅲ）/Co（Ⅱ）and Bi（Ⅴ）/Bi（Ⅲ）catalyzing PS,as well as the mutual synergistic effect between the two monomers of Co₃O₄@BiOI.Meanwhile,stability tests of the materials and environmental water bodies showed that the composite material Co₃O₄@BiOI and the Fenton-like system（Co₃O₄@BiOI/PS）both have good stability.（5）To further investigate the transformation pattern of BPAF during the oxidation process,this paper compared the mineralization rates of BPAF in Mn₃O₄/PMS,Mn_0.2Co_0.8O_x/PMS,Mn₃O₄@BiOI/PS,and Co₃O₄@BiOI/PS systems.The mineralization rate changes and main degradation pathways of BPAF in the Mn₃O₄/PMS system were the main focus.The results showed that the mineralization rate of BPAF could reach 73.2%after 90 mins of reaction,which was higher than that of other systems studied in this project.Furthermore,GC/MS,LC/MS detection methods,and DFT simulation calculation were used to analyze and study the main intermediate products during the degradation process.Finally,three main oxidation and degradation pathways of BPAF in the Mn₃O₄/PMS system were proposed.Based on the mechanism study of Mn₃O₄activated persulfate for the degradation of BPAF,this study gradually explored the preparation of three new composite catalysts:manganese-cobalt bimetallic oxide composite material(Mn_0.2Co_0.8O_x)and manganese-cobalt modified BiOI composite material（Mn₃O₄@BiOI and Co₃O₄@BiOI）,and conducted in-depth research on their efficiency and mechanism of activating persulfate to degrade BPAF.The results show that the above materials have excellent degradation performance for characteristic pollutants in water,which expands the application field of persulfate-based AOTs and provides theoretical guidance for catalytic degradation of characteristic pollutants in water.更多还原