g-C_(3)N_(4)/TiO_(2)复合薄膜光催化降解石油采出水中多环芳烃

Degradation of polycyclic aromatic hydrocarbons in oilfield produced wastewater based on g-C_(3)N_(4)/TiO_(2) composite thin film photocatalyst

针对亟待解决的石油开采废水中的多环芳烃(polycyclic aromatic hydrocarbons,PAHs)污染物的生物毒害性问题,利用紫外光辐照g-C_(3)N_(4)/TiO_(2)复合薄膜光催化剂,对取自内蒙某采油现场的采出水水样进行降解处理,研究多组分PAHs污染物共存条件下的不同环数PAHs发生光催化氧化反应的降解规律及降解动力学。采用扫描电子显微镜(scanning electron microscope,SEM)表征光催化剂表面微观形貌,采用固相微萃取法富集和萃取水样中的PAHs,采用气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)检测分析PAHs含量。经UV/gC_(3)N_(4)/TiO_(2)光催化反应处理,采出水中不溶的颗粒态萘优先于溶解态萘被降解去除,经60 min后对萘的总去除率可达61.13%。大于4环不溶性高环PAHs,可被优先光催化降解,从而高毒性的PAHs污染物被逐级转化为相对较低生物毒性的苊烯、蒽、菲、萘等,其中苊烯的含量增长最显著。结论石油采出水的外排处理工艺中增加PAHs光催化脱毒工艺具有一定可行性,对于保障原有水厂中的生化工艺段高效率、稳定运行将极具价值。

Aiming at the urgent problem regarding the biological toxicity of polycyclic aromatic hydrocarbons(polycyclic aromatic hydrocarbons,PAHs)pollutants in oilfield-produced wastewater,origina wastewater samples from an oil production site in Inner Mongolia were degraded by using UV irradiation gC_(3)N_(4)/TiO_(2) composite film photocatalyst.The photocatalytic oxidation behavior and degradation kinetics of PAHs with different benzene ring numbers were studied under the coexistence of multiple pollutants.The surface morphology of the photocatalyst was characterized by scanning electron microscopy (scanning electron microscope,SEM).PAHs in water samples were enriched and extracted by solid-phase microextraction.The content of PAHs was quantitatively analyzed by gas chromatography/mass spectrometry (gas chromatographymass spectrometry,GC-MS).The results showed that after UV/g-C_(3)N_(4)/TiO_(2) photocatalytic reaction treatment insoluble granular naphthalene was removed preferentially than dissolved naphthalene.The total removal rate of naphthalene could reach 61.13% after 60 min photocatalytic reaction.Insoluble PAHs with more than 4 benzene rings could be preferentially degraded by photocatalysis.Then the highly toxic PAHs were gradually converted into acenaphthene (Ace),anthracene (Ant),phenanthrene (Phe),naphthalene (Nap) and so on,of which the content of Ace increased significantly.The application of PAHs photocatalytic"detoxification"process in the efflux treatment of oilfield-produced water has a certain feasibility.More extensive research is worth carrying out in the future.It will be of great value to ensure the highly efficient and stable operation of the existing biochemical process in petroleum production wastewater treatment plants.