Sono-photocatalytic degradation of tetracycline and pharmaceutical wastewater using WO 3 /CNT heterojunction nanocomposite under US and visible light irradiations: A novel hybrid system.

In this paper, in-situ fabrication of tungsten oxide (WO ₃ ) on carbon nano-tube (CNT) was performed via sol-gel/hydrothermal method to prepare WO ₃ /CNT nanocomposites and then coupled with visible light and ultrasound (US) irradiations for sono-photocatalytic removal of tetracycline (TTC) and pharmaceutical wastewater treatment. The as-prepared catalysts were characterized by FT-IR, XRD, TEM, UV-VIS DRS, FESEM, EDS, TGA, BET, BJH, EIS, and EDX techniques. The characterization tests, indicated successful incorporation of CTNs into the WO ₃ framework and efficient reduction of charge carries recombination rate after modifying with CNT. The investigation of experimental parameters verified that 60 mg/L TTC could be perfectly degraded at optimum operational parameters (WO ₃ /CNT: 0.7 g/L, pH: 9.0, US power: 250 W/m ² , and light intensity: 120 W/m ² over 60 min treatment. Trapping experiments results verified that HO radicals and h ⁺ were the main oxidative species in degradation of TTC. The as-prepared photocatalysts could be reused after six successive cycles with an approximately 8.8 % reduction in removal efficiency. Investigation of the effect of real pharmaceutical wastewater revealed that this system is able to eliminate 83.7 and 90.6 % of TOC and COD, respectively after 220 min of reaction time. Some compounds with lower toxic impact and molecular weight, compared to raw pharmaceutical wastewater, were detected after treatment by sono-photocatalysis process. The biodegradability of real pharmaceutical wastewater was improved significantly after treatment by WO ₃ /CNT sono-photocatalysis.
Competing Interests: Declaration of Competing Interest No conflict of interest.
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