Abstract
Titania nanotube was prepared from sludge generated TiO2 (S-TNT) through a modified hydrothermal route and successfully composited with graphitic carbon nitride (g-CN) through a simple calcination step. Advanced characterization techniques such as X-ray diffraction, scanning and transmission electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, UV/visible diffuse reflectance spectroscopy, and photoluminescence analysis were utilized to characterize the prepared samples. A significant improvement in morphological and optical bandgap was observed. The effective surface area of the prepared composite increased threefold compared with sludge generated TiO2. The optical bandgap was narrowed to 3.00 eV from 3.18 in the pristine sludge generated TiO2 nanotubes. The extent of photoactivity of the prepared composites was investigated through photooxidation of NOx in a continuous flow reactor. Because of extended light absorption of the as-prepared composite, under visible light, 19.62% of NO removal was observed. On the other hand, under UV irradiation, owing to bandgap narrowing, although the light absorption was compromised, the impact on photoactivity was compensated by the increased effective surface area of 153.61 m2/g. Hence, under UV irradiance, the maximum NO removal was attained as 32.44% after 1 h of light irradiation. The proposed facile method in this study for the heterojunction of S-TNT and g-CN could significantly contribute to resource recovery from water treatment plants and photocatalytic atmospheric pollutant removal.
Highlights
Over the last few years, wastewater generation has increased at an exponential rate
The X-Ray Powder Diffraction (XRD) pattern of the prepared nanotubes (S-TiO2 nanotubes (TNTs), STNT1, and STN2) shows that the phase structure and the crystallinity of S-TiO2 remained intact after the modified hydrothermal treatment [25]
The estimated optical bandgaps along with the CB and VB position of S-TNT and graphitic carbon nitride (g-CN) of this study suggested the as-synthesized composite to be of type II heterojunction photocatalyst [50]
Summary
Over the last few years, wastewater generation has increased at an exponential rate. The increase in the global population, which makes the biggest contribution to the depletion of wastewater, remains a major issue for water security [1]. While the adoption of wastewater recycling methods has successfully addressed many of the pollution problems that result from the introduction of polluted water into the natural environment, the hazardous sludge that is generated during the physiochemical. Through the use of Ti-salts, viz., titanium tetrachloride (TiCl4 ), titanium sulfate (Ti(SO4 )2 ), and polymerized TiCl4 / Ti(SO4 ) , within water flocculation, it is possible to calcine the sludge to generate TiO2 , which represents a useful byproduct [5,6,7].
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