Industrial wastewater from the textile sector often contains persistent synthetic dyes like Basic Orange 14, posing significant environmental risks. To combat this, Advanced Oxidation Processes (AOPs) have gained prominence due to their ability to generate highly reactive species, primarily hydroxyl radicals (•OH), which effectively break down recalcitrant organic pollutants. Among the various AOPs, photocatalysis and ozonation stand out as particularly effective methods for degrading dyes like Basic Orange 14.

Photocatalysis involves using a semiconductor catalyst, typically titanium dioxide (TiO₂) or zinc oxide (ZnO), activated by UV or visible light. When irradiated, these catalysts generate electron-hole pairs. The holes oxidize water or hydroxide ions to form hydroxyl radicals, while the electrons reduce oxygen to superoxide radicals. Both species aggressively attack the dye molecule, leading to its fragmentation and eventual mineralization. Studies on similar reactive orange dyes demonstrate that TiO₂ and ZnO catalysts can achieve high decolorization rates, often following pseudo-first-order kinetics. Factors such as catalyst type, light intensity, pH, and catalyst loading are critical for optimizing the efficiency of this process. The synergy between the dye's structure and the photocatalyst's properties determines the overall degradation rate.

Ozonation, another potent AOP, utilizes ozone (O₃) to treat wastewater. Ozone can degrade dyes directly through molecular oxidation, primarily targeting electron-rich moieties like the azo bond, or indirectly through the generation of hydroxyl radicals at alkaline pH. This indirect pathway is particularly effective in mineralizing the dye. Research indicates that ozonation can achieve high decolorization and significant reductions in Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) for reactive dyes. Combining ozonation with biological treatment is an advantageous strategy, as the initial ozonation step breaks down the dye into more biodegradable fragments, enhancing the efficiency of subsequent biological processes. The process is influenced by pH, with alkaline conditions often favoring hydroxyl radical formation.

The effectiveness of AOPs in removing Basic Orange 14 hinges on precise control of operating parameters. For photocatalysis, this includes optimizing the semiconductor material, light source wavelength and intensity, and maintaining the appropriate pH for maximum radical generation. For ozonation, parameters like ozone dosage, pH, and contact time are crucial. Furthermore, understanding the degradation pathways and identifying intermediate products through techniques like HPLC and GC-MS is vital for ensuring that the process does not inadvertently produce more toxic byproducts.

These AOPs represent sophisticated yet powerful tools for tackling the challenge of Basic Orange 14 pollution in industrial effluents. Ongoing research aims to further enhance their efficiency, reduce energy consumption, and ensure the complete breakdown of the dye, paving the way for more sustainable industrial practices and a healthier environment.