氧掺杂氮化碳的制备及对农田环境残留农药的降解性能

Preparation of oxygen-doped carbon nitride and its degradation performance on pesticide residues in farmland

[目的]构建适用于多菌灵等4种烟-稻轮作农田常用农药的可见光催化降解技术,并阐释降解机制,为缓解农田环境农药残留造成的采收期作物农残超标问题提供理论和技术支撑。[方法]通过高温聚合法制备氧掺杂氮化碳纳米材料,通过扫描电子显微镜等表征技术分析材料微观结构。通过光催化降解试验,评价并筛选出降解性能最优的材料,同时研究复杂因素对降解过程的影响。[结果]氧元素掺杂可有效提高氮化碳纳米材料对目标农药的光催化降解性能,最优材料OCN_(0.1)对多菌灵可见光下1 h内降解率即可达到94.6%,通过活性物种捕获试验,证实在目标农药的降解过程中,活性物种的贡献度排序为h+>^(1)O_(2)>·O_(2)^(-)。OCN_(0.1)不仅能有效降解水环境残留农药,在作物生长阶段,喷施OCN_(0.1)材料48 h后,农残降解率最大也可提高39.95%。[结论]制备获得的OCN_(0.1)纳米材料,可有效降低农田环境及作物中的农药残留水平,具有良好的应用前景。

[Aims]The aims of this study are constructing photocatalytic degradation technology for 4 frequently used pesticides including carbendazim in tobacco-rice rotation fields under visible light,clarifying the degradation mechanism and providing theoretical and technical support for alleviating the problem of excessive pesticide residues in crops during the harvest period.[Methods]Oxygen-doped carbon nitride nanomaterial was synthesized via polymerization at high temperature.The microstructure of the materials was analyzed by scanning electron microscopy and other characterization techniques.The materials with the best degradation performance were evaluated and screened through the photocatalytic degradation experiment,and the influence of complex factors on the degradation process was studied.[Results]The oxygen doping process of carbon nitride effectively improved the photocatalytic degradation performance for the investigated pesticides.The degradation rate of optimized material(OCN_(0.1))for carbendazim could surpass 94.6%just in 1 h under visible light.The contribution of each ROS was quantified in the following order:h+>^(1)O_(2)>·O_(2)^(-),based on the results of trapping experiments.Apart from efficient degradation of the investigated pesticides in aqueous environment,the maximum of degradation efficiency for target pesticides in plant increased in the field conditions by 39.95%at 48 h after spraying the OCN_(0.1) material.[Conclusions]The OCN_(0.1) material can effectively reduce the level of pesticide residues in farmland environment and crops,and has a potential application prospect.