Abstract:

In order to improve sunlight utilization as well as to recycle and reuse photocatalyst of titanium dioxide, Pr³⁺:Y₂SiO₅/TiO₂/ACF composites were prepared by sol-gel technique of anchoring upconversion fluorescent material and nano-titanium dioxide on activated carbon fiber (ACF). Structures and properties of the Pr³⁺:Y₂SiO₅/TiO₂/ACF composites were characterized by XRD, FT-IR, SEM, FS, and UV-vis DRS. Photocatalytic activity of the composites in the visible light region was evaluated with methylene blue solution as model pollutant and studied the effect of fabrication conditions such as calcination temperature and number of coating layers. The experimental results showed that TiO₂ in Pr³⁺:Y₂SiO₅/TiO₂/ACF composite contained both anatase (34.1%) and rutile (65.9%) when prepared by double coating and 800℃ calcination. This composite had the highest visible-light photocatalytic activity which degraded methylene blue (15 mg·L^-1) high as 93.8% in 12 h. The photodegradation followed pseudo first order kinetics with reaction rate constant is 0.2471 h^-1. Pr³⁺:Y₂SiO₅/TiO₂/ACF composite remained degradation rate above 75% after recycled and regenerated for use four times.

Key words: upconversion, nano-titanium dioxide, composites, adsorption, degradation, regeneration

摘要：

为了提高纳米TiO₂对太阳光的利用率和实现光催化剂的回收再利用，采用溶胶-凝胶法将上转换荧光材料与纳米TiO₂复合，通过负载于活性炭纤维（ACF）表面制备了Pr³⁺：Y₂SiO₅/TiO₂/ACF复合材料。运用XRD、FT-IR、SEM、FS、UV-vis DRS等对材料的结构及性能进行了综合表征，并以亚甲基蓝为模拟污染物评价复合材料的可见光催化活性，考察了材料制备过程中煅烧温度、负载次数等制备条件对复合材料可见光下催化性能的影响。结果表明，在浸渍2次、800℃煅烧的制备条件下，复合材料中TiO₂为锐钛矿相（占34.1%）与金红石相（占65.9%）的混合相，亚甲基蓝（15 mg·L^-1）12 h内去除率高达93.8%，反应符合拟一级动力学，反应速率常数为0.2471 h^-1，回收再生利用4次后去除率仍保持在75%以上。

关键词: 上转换, 纳米TiO₂, 复合材料, 吸附, 降解, 再生