g-C3N5/β-Bi2O3复合材料催化降解盐酸四环素的性能

The photocatalytic degradation performance of tetracycline hydrochloride using g-C3N5/β-Bi2O3 composites

摘要:

以g-C3N5、Bi(NO3)3.5H2O和Na2C2O4为原料，通过水热和煅烧方式制备了g-C3N5/β-Bi2O3（CN/BO）复合材料，利用XRD、SEM、TEM、UV-Vis DRS、PL和EIS对CN/BO的结构、形貌、光电性能进行了表征。在模拟自然光条件下，测试CN/BO对盐酸四环素（TC）水溶液中TC的光催化降解性能，考察了TC水溶液质量浓度、CN/BO加入量、溶液pH、无机阴离子等对TC降解率的影响以及CN/BO的底物普适性和循环使用性能，并对CN/BO光催化降解TC的机理进行推测。结果表明，CN/BO光催化活性优于单一材料。50CN/BO（即g-C3N5的质量和β-Bi2O3质量相等）具有最佳光催化活性，在30 mL初始质量浓度为20 mg/ L的TC溶液中，50CN/BO加入量为20 mg，光照时间90 min时，光催化降解率为94.1%，总有机碳（TOC）的去除率为72.5%；光照60 min，其对罗丹明B（RhB）、孔雀石绿（MG）等6种常见水污染物的降解率为81.0%~99.8%；溶液中CO32?可降低TC的降解率，而S2O82?则可提高TC的降解率；pH＝6~12时，50CN/BO光催化性能基本不变；50CN/BO重复使用5次仍保持较高的催化活性；超氧自由基（?O2-）和空穴（h+）是CN/BO光催化降解TC反应的主要活性物种。β-Bi2O3与g-C3N5之间形成的S型异质结，提高了电荷分离和转移能力，增加了CN/BO参与光降解反应的活性基团数目。

Abstract:

The g-C3N5/β-Bi2O3 (CN/BO) composites were prepared by hydrothermal and calcination method using g-C3N5, Bi(NO3)3.5H2O and Na2C2O4 as raw materials. The structure, morphology and photoelectric properties of CN/BO were characterized by XRD, SEM, TEM, UV-Vis DRS, PL and EIS. The photocatalytic degradation performance of CN/BO was tested for TC in tetracycline hydrochloride (TC) aqueous solution under simulated natural light conditions. The effects of TC aqueous mass concentration, CN/BO dosage, solution pH and inorganic anion are investigated on the degradation rate of TC, as well as the substrate universality and recycling performance of CN/BO. And the mechanism of photocatalytic degradation of TC is speculated by CN/BO. The experiment results indicate that photocatalytic activity of CN/BO is better than a single material. 50CN/BO (the mass of g-C3N5 and β-Bi2O3 were equal) has the best photocatalytic activity. When 20 mg 50CN/BO are added in 30 mL, 20 mg/L TC solution for illumination 90 minutes, the photodegradation rate of TC and total organic carbon (TOC) removal rate are 94.1% and 72.4%, respectively. The degradation rate of six common water pollutants, such as Rhodamine B (RhB) and malachite green (MG), is 81.0%~99.8% illumination 60 minutes. CO32? can reduce the degradation rate of TC, but S2O82? can increase the degradation rate of TC in solution. The photocatalytic performance of 50CN/BO is basically unchanged when the solution of pH is 6-12. 50CN/BO is used for 5 times and still maintain high catalytic activity. The main active species are h+ and ?O- 2 groups in degradation reaction. S-type heterojunction is formed between β-Bi2O3 and g-C3N5 to improve the charge separation and transfer ability also to increase the number of active groups participated in the photodegradation reaction of CN/BO.