Advanced Removal of Dyes with Tuning Carbon/TiO₂ Composite Properties

This study evaluates the removal of several dyes with different charge properties, i.e., anionic (Acid Red 88), cationic (Basic Red 13), and neutral (Basic Red 5) using transition metal-doped TiO₂ supported on a high-surface-area activated carbon. Experimental results confirm the successful deposition of TiO₂ and the derivatives (Zr-, Cu-, and Ce-doped samples) on the surface of the activated carbon material and the development of extended heterojunctions with improved electronic properties. Incorporating a small percentage of dopants significantly improves the adsorption properties of the composites towards the three dyes evaluated, preferentially for sample AC/TiO₂_Zr. Similarly, the photodegradation efficiency highly depends on the nature of the composite evaluated and the characteristics of the dye. Sample AC/TiO₂_Zr demonstrates the best overall removal efficiency for Acid Red 88 and Basic Red 5-83% and 63%, respectively. This promising performance must simultaneously be attributed to a dual mechanism, i.e., adsorption and photodegradation. Notably, the AC/TiO₂_Ce outperformed the other catalysts in eliminating Basic Red 13 (74%/6 h). A possible Acid Red 88 degradation mechanism using AC/TiO₂_Zr was proposed. This study shows that the removal efficiency of AC/TiO₂ composites strongly depends on both the material and pollutant.