Efficient degradation of methylene blue and ciprofloxacin compounds using heteroanionic titanium oxycarbide photocatalyst and its correlation with their dielectric properties

Abstract

In recent times, semiconductor-based photocatalysts have emerged as a promising solution for remediating water pollutants. This study contributes to this field by successfully preparing a heteroanionic titanium oxycarbide photocatalyst, denoted as TiO0.5C0.5 (TiOC), through a solid-state reaction. The structural, morphological, optical, vibrational, and chemical bonding properties of TiOC were thoroughly characterized using XRD, TEM, SEM-EDS, UV–Vis DRS, FT-IR, and XPS. The photocatalytic activity of TiOC was evaluated by degrading methylene blue (MB) and ciprofloxacin (CP) under visible light (VL) irradiation in different water sources (deionized, domestic tap, and seawater). Notably, TiOC achieved significant degradation efficiencies of 79 % for MB and 82 % for CP within 180 minutes under VL in deionized water. However, its efficiencies were lower in tap water (65 % for MB, 72 % for CP) and seawater (57 % for MB, 56 % for CP) due to the presence of interfering substances (inorganic ions, radical scavengers), varying initial pH, and salinity. Additionally, dielectric permittivity measurements of TiOC at room temperature revealed a high dielectric constant (ε' ≈ 179), facilitating efficient exciton separation. Its high loss tangent (ε'' ≈ 10) is attributed to improved conductivity, enabling faster charge-carrier transfer kinetics, which contributes to the enhanced removal of MB and CP. Overall, the enhanced removal efficacy of MB and CP using TiOC is attributed to the synergistic effects of enhanced VL absorption, faster charge transfer kinetics, improved exciton separation, and a favorable pH environment.