【作者】 赵刚；

【导师】 任月萍； 蒋岚岚；

【作者基本信息】 江南大学 ， 环境工程（专业学位）， 2023， 硕士

【摘要】 磺胺甲恶唑（SMX）是使用和检出频率较高的一种抗生素,具有较高的稳定性和较差的可生化性,利用常规的污水处理技术很难将其去除,这对人类和生态系统的健康造成了严重的威胁。目前,基于硫酸根自由基(SO4^·-)的高级氧化工艺（SR-AOPs）已经被证明在去除抗生素方面存在着独特的优势。SR-AOPs是通过过硫酸盐（PS）的活化产生自由基降解污染物,其中,热活化PS由于具有操作简单,无需催化剂和不容易造成二次污染等优点被认为是最适合工程应用的SR-AOPs技术。碳气凝胶是一种轻质、多孔、非晶态的碳材料,具有高的比表面积、可控的孔径大小和良好的电化学性能,能够催化活化PS,并且在施加一定外电压后能够产生焦耳热。基于此,本文以壳聚糖为前体,采用冰模板法制备了具有垂直孔道结构的碳气凝胶,将含有SMX和PS的溶液泵入碳气凝胶垂直孔道中,利用孔道壁产生的焦耳热加热反应溶液,实现PS的快速活化和SMX的降解。主要研究内容和结论如下:（1）以壳聚糖为前体,通过冰模板法制备了具有垂直孔道结构的碳气凝胶。采用扫描电子显微镜（SEM）观察了碳气凝胶的内部形貌结构,其横截面则由蜂窝状孔组成,纵切面则显示出平行的孔道。通过X-射线光电子能谱（XPS）的表征发现,以60 g/L壳聚糖制备的碳气凝胶（CA-60）表面含有C=O、C-C、C-N、吡啶-N和石墨-N等官能团。碳气凝胶的焦耳热效应与所制备过程中壳聚糖的浓度成正相关。在外加5 V电压时,以50g/L壳聚糖制备的碳气凝胶（CA-50）的表面温度维持在～256.5 o C,而CA-60在接通电源2min内温度就飙升到344.6 oC。（2）考察了CA-60焦耳加热体系中过一硫酸盐（PMS）和过二硫酸盐（PDS）的活化效果及出水口的温度变化。同时,以初始浓度为10 mg/L的SMX以主要目标污染物,探究了不同外加电压和流速等对CA-60焦耳加热体系中SMX降解的影响。外加电压从1V增加到5 V时,出水口的平衡温度从28.3 oC升高至80.8 oC,120 min内SMX的降解率从87.5%升高到100%。流速为4 m L/min、5 m L/min和6 m L/min时,出水口的平衡温度分别为89.4 oC、80.8 oC和72.0 oC,120 min内SMX的降解率分别为98.8%、100%和100%。外加电压为5 V时,PMS在120 min内的分解率为91.8%,PDS在120 min的分解率为81.3%。另外,CA-60焦耳加热体系具有较高的稳定性,5次循环实验后,SMX的降解率仍达到91.7%。（3）通过自由基淬灭实验和电子顺磁共振波谱（EPR）分析,推测PMS主要通过CA-60的催化活化、热活化和电子直接活化三种途径生成了SO4^·-、羟基自由基（·OH）、超氧根自由基(O2^·-)和单线态氧（1O2）。其中,·OH对CA-60焦耳加热体系中SMX的降解贡献较大。除了以上的活性氧物种（ROS）对SMX的氧化分解外,体系中有部分SMX是通过电子转移机制被降解。最后,采用液相-质谱联用仪（LC-MS）检测到11种SMX的降解中间体,推测该体系中SMX可能有3种降解途径。更多还原

【Abstract】 Sulfamethoxazole（SMX）is a kind of antibiotics with high frequency of use and detection,which has high stability and poor biodegradability,so it is difficult to remove it by conventional sewage treatment technology,which poses a serious threat to human and ecosystem health.At present,the advanced oxidation process（SR-AOPs）based on sulfate radical(SO₄^·-)has been proved to have unique advantages in the removal of antibiotics.SR-AOPs is the free radical degradation of pollutants produced by the activation of persulfate（PS）.Among them,thermally activated PS is considered to be the most suitable SR-AOPs technology for engineering applications because of its advantages such as simple operation,no catalyst and not easy to cause secondary pollution.Carbon aerogel is a kind of light,porous and amorphous carbon material,which has high specific surface area,controllable pore size and good electrochemical performance.It can catalyze and activate PS and produce Joule heat when a certain external voltage is applied.Based on this,carbon aerogel with vertical pore structure was prepared by ice template method using chitosan as precursor.The solution containing SMX and PS was pumped into the vertical pore of carbon aerogel,and the reaction solution was heated by Joule heat produced by the pore wall to realize the rapid activation of PS and the degradation of SMX.The main research contents and conclusions are as follows:（1）Carbon aerogels with vertical pore structure were prepared by ice template method using chitosan as precursor.The internal morphology of carbon aerogel was observed by scanning electron microscope（SEM）.The cross section was composed of honeycomb pores and the longitudinal section showed parallel pores.Through the characterization of X-ray photoelectron spectroscopy（XPS）,it was found that the surface of carbon aerogel（CA-60）prepared with 60 g/L chitosan contained functional groups such as Coluo,Cmurc,Cmurn,pyridinic-N and graphite-N.The Joule heat effect of carbon aerogel is positively correlated with the concentration of chitosan in the preparation process.When the voltage is 5 V,the surface temperature of carbon aerogel（CA-50）prepared with 50 g/L chitosan is maintained at～256.5^oC,while the temperature of CA-60 soars to 344.6 ^oC when the power is turned on 2 min.（2）The activation effect of peroxymonosulfate（PMS）and peroxydisulfate（PDS）and the temperature change of outlet in CA-60 Joule heating system were investigated.At the same time,with the initial concentration of 10 mg/L as the main target pollutant,the effects of different applied voltage,flow rate and real water matrix on the degradation of SMX in CA-60Joule heating system were investigated.When the applied voltage increases from 1 V to 5 V,the equilibrium temperature of the outlet increases from 28.3 ^oC to 80.8 ^oC.The degradation rate of SMX increases from 87.5%to 100%within 120 min.When the flow rate is 4 m L/min,5 m L/min and 6 m L/min,the equilibrium temperature of the outlet is 89.4 ^oC,80.8 ^oC and 72.0^oC and the degradation rate of SMX is 98.8%,100%and 100%within 120 min,respectively.The decomposition rate of PMS in 120 min is 91.8%.The decomposition rate of PDS in 120min is 81.3%.In addition,the CA-60 Joule heating system has high stability.After 5 cycles,the degradation rate of SMX is still 91.7%,and the Joule heating effect and electrical conductivity of CA-60 are not significantly reduced.（3）Through free radical quenching experiment and electron paramagnetic resonance spectroscopy（EPR）analysis,it is inferred that PMS mainly produces SO₄^·-,hydroxyl radical（·OH）,superoxide radical(O₂^·-)and singlet oxygen（¹O₂）through catalytic activation,thermal activation and electron direct activation of CA-60.Among them,·OH made a great contribution to the degradation of SMX in CA-60 Joule heating system.In addition to the oxidative decomposition of SMX by the reactive oxygen species（ROS）,some SMX in the system is degraded through the electron transfer mechanism.Finally,11 kinds of SMX degradation intermediates were detected by liquid chromatography-mass spectrometry（LC-MS）.It is speculated that there may be three degradation pathways of SMX in this system.更多还原