g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3)复合材料光催化还原水中U(Ⅵ)

Photocatalytic reduction of U(Ⅵ) in wastewater with g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3) composite

采用热聚合法制备了氮化碳-氧化铋-氧化铝(g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3))光催化剂,并通过XRD、SEM、XPS等多种手段进行了表征,考察了该催化剂对模拟含铀废水中U(Ⅵ)的光催化还原性能和重复利用性能,探讨了其光催化还原U(Ⅵ)的机理。结果表明,在g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3)投加量为0.5 g/L、废水初始pH为5、U(Ⅵ)质量浓度为10 mg/L的条件下,经暗反应30 min、光反应60 min后,废水中U(Ⅵ)去除率达到98%。g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3)重复使用5次后对U(Ⅵ)的去除率仍可达85%,表现出良好的稳定性和重复利用性能。g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3)光催化剂还原U(Ⅵ)的主要机理是光生电子(e-)和超氧自由基(·O_(2)-)的作用。

The photocatalyst carbon nitride-bismuth oxide/alumina(g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3))was prepared by thermal polymerization and characterized by XRD,SEM,XPS and other means.Its photocatalytic reduction activity to U(Ⅵ)in simulated uranium-containing wastewater and its reuse performance were investigated.The mechanism of U(Ⅵ)photocatalytic reduction with g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3) was investigated.The results show that under the conditions of g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3) amount 0.5 g/L,initial pH 5,U(Ⅵ)mass concentration 10 mg/L,dark reaction time 30 min and light reaction for 60 min,the U(Ⅵ)removal rate reaches 98%.After g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3) reused for 5 times,the U(Ⅵ)removal rate can still reach 85%,showing good stability and reusability of the g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3).The main mechanism of U(Ⅵ)reduction on g-C_(3)N_(4)-Bi_(2)O_(3)/Al_(2)O_(3) photocatalyst is the action of photogenerated electron(e-)and superoxide radical(·O_(2)-).