【作者】 赵瑜；

【导师】 张凤宝； 杜俊霞；

【作者基本信息】 天津大学 ， 工程硕士（专业学位）， 2022， 硕士

【摘要】 水体中的各类有机污染物,有些甚至含量相对较少,也会对人体健康和生态系统平衡造成巨大威胁。在许多废水处理方法中,基于过一硫酸盐的非均相金属催化氧化技术因其催化氧化能力优异、p H应用范围广泛、催化剂易分离回收等优点大受欢迎。但是,非均相金属催化剂在实际应用中还存在两个主要问题,即催化剂稳定性差和金属离子易浸出。因此,本论文将采用金属与碳材料复合、以及双金属协同方法来试图解决上述问题。本论文的主要研究内容如下:（1）以乙酰丙酮钴（Co（acac）₂）为碳源和钴源,均苯三甲酸（H₃BTC）为碳源,合成了钴基金属有机框架材料（Co-MOFs）,高温热解后制得Co@C。该材料对于活化过一硫酸盐（PMS）降解双酚A表现出了优异的催化降解性能:100m L浓度为20 ppm的双酚A（BPA）污染物,在添加10 mg Co@C催化剂,0.1 g的PMS的情况下,在5min内即可完全降解。猝灭实验结果表明,硫酸根自由基(SO₄^·-),超氧自由基(O₂^·-)和单线氧（¹O₂）是主要的活性氧物种（ROSs）。（2）Mn-BTC/Co（acac）₂为前驱体,经过高温碳化成功制备一种新型棒状材料Co/Mn O-X@C,并将其用于激活PMS去除BPA。Co/Mn O-0.32@C在1 min内对BPA的去除率达98%以上,其反应速率常数(3.516 min^-1)远大于Co@C(1.076 min^-1)和Mn O@C(0.006 min^-1)。催化反应后,Co/Mn O-0.32@C（0.97mg/L）中钴离子的浸出量仅为Co@C（4.96 mg/L）的1/5。Co/Mn O-0.32的高活性和低浸出率表明:在PMS活化过程中,Co与Mn O之间存在协同作用。DFT计算表明,Co-Mn O有利于PMS的吸附和活化,进而有利于ROSs的释放。XPS结果表明:通过Co（III）/Mn（Ⅱ）氧化还原循环,生成的高活性Co（II）和Mn（Ⅲ）被用于活化PMS,这进一步证明了Co与Mn O之间存在协同作用。自由基猝灭实验,电子顺磁共振光谱（EPR）分析表明,此反应体系中,O₂^·-和¹O₂是主要的活性氧物种。开路电位（OCP）测试证明Co/Mn O-X@C表面存在直接电子转移（DET）。因此,（Co/Mn O-0.32@C）/PMS体系中,自由基和非自由基过程都存在。综上所述,本文制备的钴/锰-碳材料可高效激活过一硫酸盐,为实际水体中去除有机污染物提供新方案。此外,课题对Co与Mn O之间协同作用的深入研究,为Co-Mn O材料在基于过一硫酸盐的高级氧化技术应用中提供了理论依据。更多还原

【Abstract】 All kinds of organic pollutants in water,some of which are relatively low in content,also pose a great threat to human health and ecosystem balance.In many wastewater treatment methods,heterogeneous metal catalytic oxidation technology based on persulfate is popular because of its excellent catalytic oxidation ability,wide range of p H application,easy separation and recovery of catalyst,etc.However,there are two main problems in the practical application of heterogeneous metal catalyst,that is,poor stability of catalyst and easy leaching of metal ions.Therefore,the metal-carbon composite and bimetal synergistic methods will be adopted in this paper to try to solve the above problems.The main research contents of this paper are as follows:（1）Cobalt-based metal organic framework materials（Co-MOFs）were synthesized when using Co（acac）₂ as carbon source and cobalt source,H₃BTC as carbon source.Co@C was obtained by pyrolysis of Co-MOFs at high temperature.In degradation experiments,Co@C showed excellent catalytic degradation performance and could completely degraded 100m L of 20ppm bisphenol A（BPA）within 5min after adding 10 mg of catalyst and 0.1 g of PMS.Finally,the reaction mechanism of Co@C/PMS/BPA system was systematically studied by radical quenching experiment and open circuit potential test.The radical quenching experiment showed that the main reactive oxygen species（ROSs）were SO₄^·-,O₂^·-and ¹O₂.（2）A novel material of Co Nanoparticles anchored on Mn O nanorods wrapped in carbon layers（Co/Mn O-X@C）was successfully synthesized and applied to activate peroxymonosulfate（PMS）for Bisphenol A（BPA）degradation.More than 98%of BPA was removed by Co/Mn O-0.32@C within 1 min.The reaction rate constant of Co/Mn O-0.32@C(3.191 min^-1)was much larger than Co@C(1.076 min^-1)and Mn O@C(0.006 min^-1).The leached Co ions from Co/Mn O-0.32@C（0.97 mg/L）was only 1/5 of Co@C（4.96 mg/L）after the catalytic reaction.The high activity and low leaching rate of Co indicated the synergistic effect between Co and Mn O during PMS activation.Density functional theory（DFT）calculations revealed Mn O modified with Co was favorable for the adsorption and activation of PMS and the release of reactive oxidation species（ROSs）.The XPS results indicated the presence of Co（III）/Mn（Ⅱ）redox cycle,while the generated Co（II）and Mn（Ⅲ）was used for PMS activation,thus proving the synergistic effect further.Radical quenching experiment and electron paramagnetic resonance（EPR）analysis showed that O₂^·-and ¹O₂ were the main reactive oxygen species in the reaction system.The open circuit potential（OCP）test proved the direct electron-transfer（DET）existed on the surface of Co/Mn O-X@C.Therefore,both radical and nonradical processes were present in the（Co/Mn O-0.32@C）/PMS system.In conclusion,the Co/Mn-carbon material prepared in this paper can efficiently activate persulfate,providing a new scheme for the removal of organic pollutants in actual water.In addition,the in-depth study on the synergistic effect between Co and Mn O also provides a theoretical basis for the application of Co-Mn O materials in advanced oxidation technology based on persulfate.更多还原