Abstract

Simultaneous removal of tetracycline (TC) and hexavalent chromium (Cr(VI)) from wastewater is limited by low photocatalytic efficiency and complex catalyst recovery. This study investigates titanium carbide (TiC)-based fibrous silica KAUST Catalysis Centre (KCC-1) composites for the visible-light-driven removal of TC and Cr(VI), focusing on the effects of calcination, TiC loading (1–5 wt%), and synthesis method. Uncalcined TiC/KCC-1 outperformed the calcined catalyst due to its higher surface area, anatase content, and stronger TiC–support interaction. Among loadings, 3TiC/KCC-1 achieved the highest removal (68 % Cr(VI), 66 % TC), while one-pot synthesized TiC/KCC-1 (1P) showed superior performance (73 % Cr(VI), 72 % TC), lower energy demand (731 kWh/m3), and cost (USD 36.7) compared to the impregnated catalyst (TiC/KCC-1 (IM)). Enhanced activity is attributed to its narrow band gap (1.7 eV), efficient charge separation, and favorable band positions. Electrochemical studies revealed TiC/KCC-1 (1P) improved charge transfer and reduced resistance. Mechanistically, TiC/KCC-1 (1P) directs photogenerated electrons toward Cr(VI) reduction via its +0.70 eV conduction band, while its +2.4 eV valence band supports TC oxidation through hydroxyl radical formation. In contrast, TiC/KCC-1 (IM) suffers from electron competition and insufficient oxidative potential due to its less favorable band positions. These findings underscore TiC/KCC-1 (1P) as a promising, green, energy-efficient photocatalyst for multi-contaminant wastewater treatment. © 2025 Elsevier Ltd