β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)复合水凝胶材料的制备及其应用

Preparation and application ofβ-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4) composite hydrogel

为了有效解决日益严重的水污染问题,本文研究了β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)复合材料的制备及其在可见光下催化降解亚甲基蓝模拟废水的最佳工艺条件。首先,利用溶剂热法合成了β-NaYF_(4):Yb^(3+),Tm^(3+),再将煅烧法制备的g-C_(3)N_(4)加入聚丙烯酸/聚乙烯醇水溶液,后滴入饱和硼酸溶液获得β-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)/聚丙烯酸/聚乙烯醇复合水凝胶。利用X射线衍射仪、场发射扫描电子显微镜、紫外-可见分光光度计、热重分析仪、全自动比表面积微孔孔隙分析仪等进行表征;利用正交试验L_(16)(4^(5))考察复合材料的投加量、复合材料的比例、温度、亚甲基蓝溶液的pH、光照时间等因素,探索降解亚甲基蓝的最佳工艺条件。正交试验结果表明:光照时间为20.0h、pH为7.00、复合材料的投加量0.25g、温度20.0℃、复合材料活性组分β-NaYF_(4):Yb^(3+),Tm^(3+)与g-C_(3)N_(4)的比例为1∶4,此时对30.0mg/L亚甲基蓝降解率达到94.84%,循环降解亚甲基蓝模拟废水4次后的降解率仍高达为86.22%。

To deal with the problem of water pollution effectively,the preparation ofβ-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)composites and the optimum conditions for photocatalytic degrading methylene blue wastewater under visible light were studied.β-NaYF_(4):Yb^(3+),Tm^(3+)and g-C_(3)N_(4)were synthesized by solvothermal method and calcinations method,respectively.Then,β-NaYF_(4):Yb^(3+),Tm^(3+)and g-C_(3)N_(4)were mixed and added into the solution of polyacrylic acid-polyvinyl alcohol.Theβ-NaYF_(4):Yb^(3+),Tm^(3+)/g-C_(3)N_(4)/PAA/PVA composite hydrogel was formed by adding the above mixed solution to the saturated borate aqueous solution dropwise with hard stirring.The products were characterized by X-ray diffractometer,field emission scanning electron microscope,UV-visible spectrophotometer,thermal gravimetric analyzer and specific surface area microporous pore analyzer and so on.The orthogonal experiment L_(6)(4^(5))was used to explore the optimal conditions for degrading methylene blue.The results showed that the degradation rate of methylene blue in 30mg/L was 94.84%under the optimal conditions of the illumination time 20.0 h,the pH value 7.00,the dosage of composite materials 0.25 g,the temperature 20.0℃and the ratio of active materialβ-NaYF_(4):Yb^(3+),Tm^(3+)to g-C_(3)N_(4)1∶4.Moreover,the degradation rate of methylene blue in simulated wastewater was still up to 86.22%after 4 recycles.This study revealed that the prepared composite had a good practical value for the application in wastewater treatment.