Degradation of Sulfamethoxazole by Double Cylindrical Dielectric Barrier Discharge System combined with Ti /C-N-TiO₂ supported Nanocatalyst

The presence and detection of persistent pharmaceutical pollutants (PPPs) in aquatic environments requires urgent remediation. C-N-TiO₂ was prepared by sol-gel method and immobilised on Ti mesh by dip-coating technique followed by pyrolysis in the furnace at 350°C for 105 minutes. The Ti/C-N-TiO₂ photocatalyst were characterised by SEM, EDS, XRD, Raman spectroscopy, and XPS. An optimised DCDBD system alone or combined with Ti/C-N-TiO₂ catalysts were compared for the degradation of sulfamethoxazole (SMX) simulated wastewater at the applied conditions. The SEM-EDS results showed that C, N, and Ti were all present in the C-N-TiO₂ nano catalyst layer supported upon Ti mesh. XPS results revealed existence of Ti in +4 oxidation states despite the addition carbon and nitrogen. The XRD and Raman patterns confirmed the formation of anatase as dominant phase. The antibacterial tests of Ti/C-N-TiO₂ films showed an excellent effect on E. coli inhibition. The degradation of SMX with DCDBD and DCDBD/C-N-TiO₂/Ti-mesh systems followed first-order reaction and complete mineralisation of the pollutants was achieved after 30 and 60 min of plasma run at rate constants of 3.79×10⁻² min⁻¹ (R² = 0.999) and 2.18×10⁻² min⁻¹ (R² = 0.997), respectively. The energy yield G₅₀ required for the degradation of 50% SMX reached 34.64 g/kWh corresponding to an electrical efficiency per order (EE/O) of 40.527 kWh/m³ order¹ with DCDBD alone within 18 min, and 19.787 g/kWh with DCDBD/Ti/C-N-TiO₂ system corresponding to an EE/O of 70.458 kWh/m³ order¹ after 32 min. Different recalcitrant degradation intermediate by-products were detected by HPLC/MS and their degradation pathways proposed. Therefore, this study offers a novel advanced oxidation technology for the remediation of SMX from aqueous solution.