|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|6453571||1418800||2018||11 صفحه PDF||سفارش دهید||دانلود رایگان|
- UV-LED/TNAs could be efficient for photocatalytic degradation of metoprolol (MTP).
- Morphology and crystalline composition of TNAs have impact on MTP degradation.
- Operational parameters affecting UV-LED/TNAs MTP degradation were studied.
- Bicarbonate ions were found to be able to quench conduction band electrons.
- MTP degradation mechanisms in UV-LED/TNAs treatment was elucidated.
The aim of this study was to evaluate the use of self-organized TiO2 nanotube arrays (TNAs) as immobilized catalyst and UV-LED as light source (UV-LED/TNAs) for photocatalytic degradation of the Î²-blocker metoprolol (MTP) from aqueous solution. Firstly we employed electrochemical anodization to synthesize self-organized TNAs, and the effect of anodization potential and annealing temperature was examined. Characterization by SEM demonstrated a linear relation between the diameter of TiO2 nanotubes produced and the anodization potential, while Raman measurement revealed the vital role of annealing on crystallographic composition of the anodic produced TiO2 nanotubes. Regarding their performance in photocatalytic MTP degradation, surface morphology and crystallographic composition of the TNAs were found to impose crucial influence: only TNAs with diameter not smaller than 53Â nm enabled rapid MTP degradation, and highest MTP degradation was obtained when a mixture of anatase and rutile were present in the TNAs. Secondly, the effect of operational parameters, i.e initial MTP concentration, pH, was investigated. Initial MTP concentration at low level had no detrimental effect on the process performance. Rapid MTP degradation and high total removal were achieved in a wide pH range (3-11). To evaluate the applicability of TNAs for water treatment, experiments were first carried out in the presence of three different commonly present water constituents, i.e bicarbonate ions, phosphate ions, and natural organic matters (NOMs). The results show that bicarbonate and phosphate ions have no inhibitory effect at concentration levels up to 200Â mg/L, and NOMs exhibit detrimental effect when their concentration exceeds 5Â mg/L. The total removal MTP degradation reduced from 87.09Â Â±Â 0.09% to 62.05Â Â±Â 0.08% when tap water samples were applied, demonstrating reasonable efficacy for practical applications. Regarding the degradation mechanism, formic acid and tert-butanol were added as scavenger for photo-generated holes (h+) and hydroxyl radicals (Â·OH), respectively. The obtained results demonstrate that primary degradation process occurred in liquid phase with participation of hydroxyl radicals in the liquid phase (Â·OH liquid), while smaller portion of MTP were degraded on the catalysis surface via reaction with h+ and hydroxyl radicals adsorbed on the catalyst surface (Â·OH surface). Other reactive species, e.g photo generated electrons and superoxide radical anions, did also play a minor role in MTP degradation. The mechanistic aspect was further confirmed by identification of degradation products by LC-MS/MS. The TNAs exhibited good stability after repeated use under varied operation conditions.
Journal: Applied Catalysis B: Environmental - Volume 220, January 2018, Pages 171-181