Abstract:

In the persulfate advanced oxidation process, the low regeneration efficiency of Co²⁺ is the main problem of Co efficient activation of peroxymonosulfate ( PMS ). The photocatalyst of carbon nanotubes loaded with oxygen defect-rich bismuth oxide (x%CNT-Co/Bi₂O₃) was successfully prepared for photocatalytic synergistic persulfate activation and degradation of pollutants. When the initial pH is 4.68 and PMS concentration is 0.5 mmol/L, the degradation of tetracycline(TC) is up to 91.3% under UV light (λ=254 nm) irradiation with 20 mg/L 70%CNT-Co/Bi₂O₃ as catalyst. It has excellent reusability and stability. The improved degradation activity is attributed to the great specific surface area of carbon nanotubes which is favorable to the adsorption of TC. Besides, the photogenerated electrons accelerate the cycle rate of Co²⁺→Co³⁺→Co²⁺, which promotes the separation and migration of photogenerated charges and the activation of PMS, so that a rapid degradation of TC is realized. In addition, Bi₂O₃ is uniformly dispersed on the outer tube wall of CNT-Co, which avoids the agglomeration of Bi₂O₃ nanoparticles. CNT-Co has a large specific surface area, which is conducive to the adsorption of pollutants on the surface of the catalyst and increases the adsorption effect. The system produces a variety of active species, and its contribution is ¹O₂>·SO${}_{\mathrm{4}}^{-}$>·OH>·O${}_{\mathrm{2}}^{-}$, which can realize the efficient degradation of pollutants by free radical and non-free radical.

Key words: activation, catalysis, degradation, tetracycline, CNT-Co, Bi₂O₃

摘要：

在过硫酸盐高级氧化技术中，Co²⁺的再生效率低是Co高效活化过一硫酸盐（PMS）的主要问题。成功制备了富含氧缺陷氧化铋负载碳纳米管（x%CNT-Co/Bi₂O₃）光催化剂，用于光催化协同过硫酸盐活化降解污染物。在紫外线照射下，催化剂添加量为20 mg/L、PMS浓度为0.5 mmol/L和初始pH为4.68时，70%CNT-Co/Bi₂O₃对四环素（TC）的降解率高达91.3%，具有优异的可重复利用性和稳定性。其降解活性的提高归因于CNT-Co具有极大的比表面积，有利于TC吸附，光生电子加速Co²⁺→Co³⁺→Co²⁺的循环速率，既促进光生电荷的分离与迁移，又促进PMS的活化，实现TC的快速降解。此外，Bi₂O₃均匀分散在CNT-Co外管壁上，避免了Bi₂O₃纳米颗粒的团聚，CNT-Co具有较大的比表面积，有利于污染物吸附于催化剂表面，增加吸附效果。该体系产生多种活性物种，其贡献度为¹O₂>·SO${}_{\mathrm{4}}^{-}$>·OH>·O${}_{\mathrm{2}}^{-}$，可实现自由基和非自由基双通路高效降解污染物。

关键词: 活化, 催化, 降解, 四环素, CNT-Co, Bi₂O₃