新型自支撑锑锡氧化物电极氧化降解阿特拉津性能研究

Self-supporting Sb-doped SnO_(2) Anode for Oxidative Degradation of Atrazine

阿特拉津(ATZ)作为农业领域广泛应用的除草剂,其分子结构稳定,残留周期长,难以通过自然途径有效降解,长期积累对生态环境及人类健康构成显著威胁。当前,Sb掺杂SnO_(2)(ATO)电极被广泛应用于电化学氧化降解污染物领域,但目前基于ATO材料制备电极通常是在平面基底上涂覆催化剂层,由于传质受限且电荷转移阻抗较大,ATO电极的反应速率受限,有机污染物去除速率较慢。鉴于此,开发新型高效稳定的电极材料成为解决上述问题的关键。为提升ATO电极的传质性能与结构稳定性,以果糖为成孔剂,采用压片成型与高温烧结技术,成功制备了一体成型的自支撑3维多孔ATO(Fru-ATO)阳极。利用扫描电子显微镜(SEM)与X射线衍射分析仪(XRD)等设备对电极的形貌特征与结晶性能进行详尽表征,并系统研究了不同烧结温度对阳极结构及其性能的影响。此外,通过调整溶液初始pH值、电解质浓度及施加电流密度等条件,进一步优化了ATZ的电化学降解效果。结果表明,随着烧结温度的升高,Fru-ATO阳极材料的颗粒尺寸逐渐增大,XRD图谱显示其结晶度显著提升,峰形更尖锐且峰强增强,同时析氧电位正向移动,对ATZ的降解效率也显著提高。在优化的实验条件下(pH=6,Na_(2)SO_(4)电解质溶液浓度为0.1mol/L,电流密度为10.0mA/cm^(2)),1000℃下烧结6h所得Fru-ATO(1000-Fru-ATO)阳极在30min内可降解90%的ATZ(20mg/L),60min内降解效率达到99%,且经10次循环实验后仍保持优异的循环稳定性。进一步通过液相色谱-三重四极杆质谱联用技术,鉴定出ATZ降解过程中的17种中间产物,并据此提出了3条可能的降解路径。成功制备了具有高结晶度与3维多孔结构的Fru-ATO阳极,该电极不仅内部氧化锡结构排列有序,促进了电催化氧化过程中的电荷转移,而且其多孔结构有效暴露了更多活性位点,显著提高了传质效率。这种传质与电荷转移的双重增强机制,极大地促进了活性氧物种(尤其是单线态氧^(1)O_(2))的生成,从而实现了ATZ的快速高效降解。

Objective Highly active and stable anodes are crucial for efficiently removing persistent organic pollutants such as atrazine(ATZ)using electrooxidation technology.Sb-doped SnO_(2)(ATO)materials exhibit high oxygen evolution potential,but commonly prepared planar ATO electrodes face removal rate and stability limitations due to slow mass transfer and large charge transfer impedance.This study proposes a compression-sintering method using fructose as a pore-forming reagent to prepare self-supporting 3-dimensional porous ATO(Fru-ATO)anodes for highly efficient and stable ATZ removal.Methods The Fru-ATO anode is initially prepared using fructose particles as the pore-forming reagent through compression and sintering.The effect of sintering temperature on the anode’s structure and performance is investigated by characterizing the electrode morphology and crystallinity with scanning electron microscopy(SEM)and X-ray diffraction analyzer(XRD)and analyzing their electro-oxidation performance.Secondly,the optimization of initial solution pH,electrolyte concentration,and applied current density is conducted to achieve a better degradation rate of ATZ.Under optimized conditions,the performance of 1000-Fru-ATO in actual water and cycling tests is investigated.Finally,the reactive oxygen species generated on 1000-Fru-ATO are investigated through quenching experiments and in-situ electron paramagnetic resonance characterization.In addition,intermediate products in the degradation process of ATZ and possible degradation pathways are proposed based on liquid chromatography-triple quadrupole mass spectrometry(UPLC-MS/MS).Results and Discussions With the increase in sintering temperature,the size of particles in the anode increases,the XRD peak becomes sharper and higher,the potential for oxygen evolution reaction gradually shifts positively,and the performance in catalyzing ATZ degradation improves.Based on the 1000-Fru-ATO anode,acidic and neutral initial solutions showed higher ATZ degradation rates,with the corresponding k for pH=6 reaching 0.071 min-1.The concentration of Na_(2)SO_(4) electrolyte exerts a volcano-like influence on the ATZ degradation rate,with the highest k of 0.071 min-1 in 0.1 mol/L.The ATZ degradation rate increases monotonically as the applied current density rises,while the lowest energy consumption is observed at 10 mA/cm_(2).Under the optimized condition of 0.1 mol/L Na_(2)SO_(4) electrolyte solution at the initial solution pH and an applied current density of 10 mA/cm^(2),the 1000-Fru-ATO anode degrades 90% of ATZ(20 mg/L)within 30 min and 99% within 60 min and maintains good cycling stability in a ten-cycle test.With actual water from Xinlin Bay,Xiamen,the 1000-Fru-ATO anode still degrades 90.2% of ATZ(20 mg/L)within 60 min.In addition,the quenching experiment and in-situ electron paramagnetic resonance showed that singlet oxygen is the dominant reactive oxygen species for the rapid ATZ degradation on the 1000-Fru-ATO anode.In addition,17 intermediates of the ATZ degradation process are identified by UPLC-MS/MS,based on which three possible degradation pathways are proposed.Five reaction processes are mainly involved in ATZ degradation on the 1000-Fru-ATO anode,including dealkylation,dechlorohydroxylation,alkyl hydroxylation,alkyl oxidation,and hydroxylation.The electrode possesses a 3-dimensional porous structure that exposes more active sites and improves mass transfer efficiency.As a result,the simultaneous enhancement of mass transfer and charge transfer and the suppressed oxygen evolution promotes the generation of three reactive oxygen species,especially singlet oxygen,leading to the effective and rapid degradation of ATZ.Conclusions The results demonstrate the feasibility of the proposed method with fructose pore-forming reagent to prepare highly active and stable ATO anodes for efficiently and stably electro-oxidizing ATZ.This method can also be extended to other catalyst anode preparations and other persistent organic pollutant removals and would inspire more advances in preparing self-supported 3D porous electrodes with organic powder of small molecular weight as pore-forming reagents.