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International audience; In this study, we show that the combination of a photocatalytic process (as a pretreatment step) combined with the conventional biological treatment of wastewaters can improve the process and achieve satisfactory efficiency. In this context, Reactive Green 12 (RG-12) solutions were photocatalytically pretreated using TiO(2)-impregnated polyester as supported catalyst under UV light in batch reactor. Photocatalysis as pretreatment (during 4 and 8 h of irradiation) was combined with 7 days of aerobic biological treatment using activated sludge. As first assays, respiratory tests revealed that the removal of RG-12 was improved by 5.4% and 11.7% for the solutions that were irradiated for 4 and 8 h in the presence of TiO(2), respectively. However, 34.5% and 19% of dye solution was discolored after 7 days of biological treatment for the pretreated solutions during 4 and 8 h of UV light exposure, respectively. The discoloration efficiency obtained by the combined processes achieved 59.6% and 74.9% for the samples under photocatalysis during 4 and 8 h, respectively. A significant decrease in chemical oxygen demand (COD) of about 74.9% was achieved after photocatalysis/biodegradation processes. In addition, a decrease in the phytotoxicity was obtained as followed by the germination index (GI) values of cress seeds that increased from 46.2 to 88.7% after 8 h of photocatalysis and then to 92.8% after further 7 days of biological treatment.

International audience; In the present study, we propose a new photocatalytic interface prepared by high-power impulse magnetron sputtering (HiPIMS), and investigated for the degradation of Reactive Green 12 (RG12) as target contaminant under visible light light-emitting diodes (LEDs) illumination. The CuO/TiO₂ nanoparticulate photocatalyst was sequentially sputtered on polyester (PES). The photocatalyst formulation was optimized by investigating the effect of different parameters such as the sputtering time of CuO, the applied current, and the deposition mode (direct current magnetron sputtering, DCMS or HiPIMS). The results showed that the fastest RG12 degradation was obtained on CuO/TiO₂ sample prepared at 40 A in HiPIMS mode. The better discoloration efficiency of 53.4% within 360 min was found in 4 mg/L of RG12 initial concentration and 0.05% Cu/PES as determined by X-ray fluorescence. All the prepared samples contained a TiO₂ under-layer with 0.02% Ti/PES. By transmission electron microscopy (TEM), both layers were seen uniformly distributed on the PES fibers. The effect of the surface area to volume (dye volume) ratio (SA/V) on the photocatalytic efficiency was also investigated for the discoloration of 4 mg/L RG12. The effect of the presence of different chemicals (scavengers, oxidant or mineral pollution or salts) in the photocatalytic medium was studied. The optimization of the amount of added hydrogen peroxide (H₂O₂) and potassium persulfate (K₂S₂O₈) was also investigated in detail. Both, H₂O₂ and K₂S₂O₈ drastically affected the discoloration efficiency up to 7 and 6 times in reaction rate constants, respectively. Nevertheless, the presence of Cu (metallic nanoparticles) and NaCl salt inhibited the reaction rate of RG12 discoloration by about 4 and 2 times, respectively. Moreover, the systematic study of reactive oxygen species' (ROS) contribution was also explored with the help of iso-propanol, methanol, and potassium dichromate as OH radicals, holes (h⁺), and superoxide ion-scavengers, respectively. Scavenging results showed that O₂ played a primary role in RG12 removal; however, OH radicals' and photo-generated holes' (h⁺) contributions were minimal. The CuO/TiO₂ photocatalyst was found to have a good reusability and stability up to 21 cycles. Ions' release was quantified by means of inductively coupled plasma mass spectrometry (ICP-MS) showing low Cu-ions' release.

International audience; In the present work, we investigate the degradation of recalcitrant industrial textile dye (Reactive green 12) in aqueous solution by TiO2 impregnated polyester at room temperature. The TiO2 loading on polyester was optimized using different polyester pretreatments (plasma surface activation and UV-C photons). The applied surface pretreatments led to slightly different microstructure, crystalline sizes and photocatalytic activities. Both catalyst tests showed no photocatalytic activity for Radio-Frequency plasma (from now as “RF-plasma”) pretreated polyester under visible light and a lower activity compared to UVC-pretreated-impregnated-fabrics under UV light. This was attributed to the TiO2 aggregation on the surface of RF-plasma activated polyester. However, the photocatalytic performance of UV-C activated catalyst was investigated studying the optimal reaction conditions such as pollutant initial concentration, applied light (UV or Visible), catalyst loading and the presence of hydrogen peroxide at different concentrations. Under optimized operating conditions, namely catalyst dose of 5.18 g/L and an initial dye concentration of 2 mg/L, the removal of Reactive green 12 reached 100% under UV light and 87.14% under visible light within 120 min. Moreover, the presence of hydrogen peroxide showed a positive impact on the degradation, since the time needed for total dye decreased to 80 min under UV light irradiation for a [H2O2] to [RG 12]0 ratio in the range 20–30. The kinetic results showed that the removal of this recalcitrant dye nearly followed a Langmuir-Hinshelwood (L-H) model with a regression coefficient (R2) value of 0.926. The catalyst activity was found to be stable for more than five reuse cycles. © 2017 Elsevier B.V.

In the present study, we propose a new photocatalytic interface prepared by high-power impulse magnetron sputtering (HiPIMS), and investigated for the degradation of Reactive Green 12 (RG12) as target contaminant under visible light light-emitting diodes (LEDs) illumination. The CuxO/TiO2 nanoparticulate photocatalyst was sequentially sputtered on polyester (PES). The photocatalyst formulation was optimized by investigating the effect of different parameters such as the sputtering time of CuxO, the applied current, and the deposition mode (direct current magnetron sputtering, DCMS or HiPIMS). The results showed that the fastest RG12 degradation was obtained on CuxO/TiO2 sample prepared at 40 A in HiPIMS mode. The better discoloration efficiency of 53.4% within 360 min was found in 4 mg/L of RG12 initial concentration and 0.05% Cuwt/PESwt as determined by X-ray fluorescence. All the prepared samples contained a TiO2 under-layer with 0.02% Tiwt/PESwt. By transmission electron microscopy (TEM), both layers were seen uniformly distributed on the PES fibers. The effect of the surface area to volume (dye volume) ratio (SA/V) on the photocatalytic efficiency was also investigated for the discoloration of 4 mg/L RG12. The effect of the presence of different chemicals (scavengers, oxidant or mineral pollution or salts) in the photocatalytic medium was studied. The optimization of the amount of added hydrogen peroxide (H2O2) and potassium persulfate (K2S2O8) was also investigated in detail. Both, H2O2 and K2S2O8 drastically affected the discoloration efficiency up to 7 and 6 times in reaction rate constants, respectively. Nevertheless, the presence of Cu (metallic nanoparticles) and NaCl salt inhibited the reaction rate of RG12 discoloration by about 4 and 2 times, respectively. Moreover, the systematic study of reactive oxygen species&rsquo, (ROS) contribution was also explored with the help of iso-propanol, methanol, and potassium dichromate as &bull, OH radicals, holes (h+), and superoxide ion-scavengers, respectively. Scavenging results showed that O2&minus, played a primary role in RG12 removal, however, &bull, OH radicals&rsquo, and photo-generated holes&rsquo, (h+) contributions were minimal. The CuxO/TiO2 photocatalyst was found to have a good reusability and stability up to 21 cycles. Ions&rsquo, release was quantified by means of inductively coupled plasma mass spectrometry (ICP-MS) showing low Cu-ions&rsquo, release.