Visible light activation of photocatalysts formed from the heterojunction of sludge-generated TiO 2 and g-CN towards NO removal

The feasibility of preparing TiO /g-CN heterojunction from Ti-incorporated dried dye wastewater sludge is explored in this study. Two reaction routes of composite formation were evaluated. In the initial approach, one-step calcination of dried sludge and melamine mixture @600 °C was carried out. Det...

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Bibliographic Details
Published inJournal of hazardous materials Vol. 422; p. 126919
Main Authors Hossain, Sayed Mukit, Tijing, Leonard, Suzuki, Norihiro, Fujishima, Akira, Kim, Jong-Ho, Shon, Ho Kyong
Format Journal Article
LanguageEnglish
Published Netherlands 15.01.2022
Subjects
Catalysis
Light
Sewage
Titanium
TiO/g-CN heterojunction
Sludge-generated TiO
Resource recovery
Visible light activation
N-doped TiO
Photooxidation of NO
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Summary:The feasibility of preparing TiO /g-CN heterojunction from Ti-incorporated dried dye wastewater sludge is explored in this study. Two reaction routes of composite formation were evaluated. In the initial approach, one-step calcination of dried sludge and melamine mixture @600 °C was carried out. Detailed morphological and chemical characterizations showed that the one-step calcination route did not create TiO /g-CN composites; instead, only N-doped anatase TiO composites were formed. Moreover, due to the non-uniform composition of organic content in the dried sludge, it was not easy to control the N doping level by varying melamine content (0-100%) in the precursor mix. However, successful formation of anatase TiO and g-CN was observed when a two-step calcination route was followed, i.e., via synthesis of anatase TiO from dried sludge, and later development of heterojunction by calcining (@550 °C) the TiO and melamine mixture. X-ray diffraction along with infrared and X-ray photoelectron spectroscopy verified the effective heterojunction. In addition, maximum atmospheric NO removal under UV and visible light were observed for the prepared composite when the melamine content in the precursor mixture was 70%. After 1 h of UV and visible light irradiation, the best TiO /g-CN composite removed 25.71% and 13.50% of NO, respectively. Optical characterization suggested that the enhanced NO oxidation under UV/visible light was due to the bandgap narrowing and diminished photogenerated electron-hole recombination.
ISSN:1873-3336