Mesoporous TiO2 implanted ZnO QDs for the photodegradation of tetracycline: material design, structural characterization and photodegradation mechanism
A sol-gel method was used to prepare a mesoporous TiO2 implanted with a ZnO quantum dot photocatalyst (TZQ) for the photodegradation of tetracycline (TC) under fluorescent light irradia�tion. Scanning electron microscopy (SEM) shows the presence of cavities on the photocatalyst surface due to the u...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | en |
| Published: |
Multidisciplinary Digital Publishing Institute (MDPI)
2021
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/92929/7/92929_Mesoporous%20TiO2%20implanted%20ZnO%20QDs.pdf http://irep.iium.edu.my/92929/ https://www.mdpi.com/2073-4344/11/10/1205/htm |
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| Summary: | A sol-gel method was used to prepare a mesoporous TiO2
implanted with a ZnO quantum dot photocatalyst (TZQ) for the photodegradation of tetracycline (TC) under fluorescent light irradia�tion. Scanning electron microscopy (SEM) shows the presence of cavities on the photocatalyst surface due to the use of starch as a synthetic template, where the nitrogen sorption results indicate that TZQ contains mesopores with reduced size (ca. 4.3 nm) versus the pore size of the parent meso-TiO2 (ca. 7.5 nm). The addition of ZnO quantum dots (QDs) resulted in spherically-shaped binary composite particles in layers onto the surface of TiO2. The coexistence of the ZnO QDs and TiO2 phase was observed using high resolution-transmission electron microscopy (HR-TEM). The photodegradation of TC was carried out in a homemade reactor equipped with two fluorescent lights (24 W each) and
within 90 min of irradiation, 94.6% of TC (40 mg L−1) was photodegraded using 250 mg L−1 of TZQ at pH 9. The major reactive oxygen species identified from the scavenging tests were O2 •− followed by HO•. The deconvolution of the photoluminescence spectrum of TZQ indicates the presence of a strong quantum confinement effect (QCE) of the ZnO QDs, a defect related to Ti-species and oxygen. The analysis of the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS) suggest two photodegradation pathways. The pathways were validated using the Fukui function approach and the Wheland localisation approach. This simple and efficient photocatalytic technology is anticipated to benefit small-scale animal husbandries and aquaculture operators that have limited access to sustainable water treatment technology |
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