The photocatalytic removal of Reactive Black 5 (RB5) was investigated using a titanium dioxide-polyethylene terephthalate (TiO2-PET) catalyst under visible (VIS) light. The sol-gel method was employed for the fabrication of the TiO2-coated PET catalyst, which was then characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and elemental mapping (MAP) analysis. This study examined the reaction kinetics using the one-factor-at-a-time (OFAT) approach and evaluates the effects of various parameters, including pH (3–11), catalyst dosage (0.1–1 g L− 1), contact time (15–120 min), RB5 concentration (10–50 mg L− 1), hydrogen peroxide (H2O2) content (2–100 mM), purging gases, organic compound types, and ionic strength, on the photocatalytic removal of RB5. Under optimal conditions (pH= 3, [RB5]°= 20 mg L− 1, nanocatalyst dosage= 0.5 g L− 1), 99.99% of the dye was removed after 120 min. Increasing the RB5 concentration (10–50 mg L− 1) resulted in a decrease in the observed reaction rate constant (kobs) from 0.052 to 0.0017 min− 1, while the calculated electrical energy per order (EEO) increased from 11.08 to 338.82 kWh m− 3. Furthermore, the total operating cost of the light emitting diode (LED)/TiO2-PET process (3 USD kg− 1) was lower than that of other photocatalytic processes, including LED/TiO2 (4.73 USD kg− 1), LED/PET (40 USD kg− 1), and LED (63.16 USD kg− 1). The removal of RB5 was negatively affected by the presence of H2O2, O2 and N2 gases, organic compounds, and ionic species. Radical quenching experiments confirmed that hydroxyl radicals (·OH) were the dominant reactive species responsible for RB5 degradation. The RB5 removal efficiency using the LED/TiO2-PET method (99.99%) was significantly higher than that of the LED/TiO2 method (63.42%). Desorption experiments demonstrated excellent catalyst stability, maintaining catalytic activity for up to five sequential cycles. GC-MS analysis identified several intermediate degradation products, including 1,2-benzenedicarboxylic acid, benzoic acid (2-amino-, methyl ester), benzene [(methylsulfonyl) methyl], phenol, 4-naphthalenedione, acetic acid, and propionic acid. Moreover, the removal efficiency in drinking water samples was approximately 63.31%, whereas for real textile wastewater samples, it reached 96.66%. Toxicity tests conducted on the final treated solutions confirmed no toxicity toward Daphnia magna, demonstrating the effectiveness of the LED/TiO2-PET method in degrading both RB5 dye and its toxic by-products.

Photocatalytic degradation of reactive black 5 from synthetic and real wastewater under visible light with TiO₂ coated PET photocatalysts

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2025年4月24日

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Mohsen Mohammadi-Galangash,
Seyedeh-Khadijeh Mousavi,
Mehdi Shirzad-Siboni

摘要

The photocatalytic removal of Reactive Black 5 (RB5) was investigated using a titanium dioxide-polyethylene terephthalate (TiO₂-PET) catalyst under visible (VIS) light. The sol-gel method was employed for the fabrication of the TiO₂-coated PET catalyst, which was then characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and elemental mapping (MAP) analysis. This study examined the reaction kinetics using the one-factor-at-a-time (OFAT) approach and evaluates the effects of various parameters, including pH (3–11), catalyst dosage (0.1–1 g L^− 1), contact time (15–120 min), RB5 concentration (10–50 mg L^− 1), hydrogen peroxide (H₂O₂) content (2–100 mM), purging gases, organic compound types, and ionic strength, on the photocatalytic removal of RB5. Under optimal conditions (pH= 3, [RB5]_°= 20 mg L^− 1, nanocatalyst dosage= 0.5 g L^− 1), 99.99% of the dye was removed after 120 min. Increasing the RB5 concentration (10–50 mg L^− 1) resulted in a decrease in the observed reaction rate constant (k_obs) from 0.052 to 0.0017 min^− 1, while the calculated electrical energy per order (EEO) increased from 11.08 to 338.82 kWh m^− 3. Furthermore, the total operating cost of the light emitting diode (LED)/TiO₂-PET process (3 USD kg^− 1) was lower than that of other photocatalytic processes, including LED/TiO₂ (4.73 USD kg^− 1), LED/PET (40 USD kg^− 1), and LED (63.16 USD kg^− 1). The removal of RB5 was negatively affected by the presence of H₂O₂, O₂ and N₂ gases, organic compounds, and ionic species. Radical quenching experiments confirmed that hydroxyl radicals (^·OH) were the dominant reactive species responsible for RB5 degradation. The RB5 removal efficiency using the LED/TiO₂-PET method (99.99%) was significantly higher than that of the LED/TiO₂ method (63.42%). Desorption experiments demonstrated excellent catalyst stability, maintaining catalytic activity for up to five sequential cycles. GC-MS analysis identified several intermediate degradation products, including 1,2-benzenedicarboxylic acid, benzoic acid (2-amino-, methyl ester), benzene [(methylsulfonyl) methyl], phenol, 4-naphthalenedione, acetic acid, and propionic acid. Moreover, the removal efficiency in drinking water samples was approximately 63.31%, whereas for real textile wastewater samples, it reached 96.66%. Toxicity tests conducted on the final treated solutions confirmed no toxicity toward Daphnia magna, demonstrating the effectiveness of the LED/TiO₂-PET method in degrading both RB5 dye and its toxic by-products.

Photocatalytic degradation of reactive black 5 from synthetic and real wastewater under visible light with TiO2 coated PET photocatalysts

摘要

Photocatalytic degradation of reactive black 5 from synthetic and real wastewater under visible light with TiO₂ coated PET photocatalysts