Advanced Oxidation Processes (AOPs) are water treatment techniques designed to remove organic and inorganic contaminants by generating highly reactive species, primarily hydroxyl radicals (•OH). These radicals are powerful oxidants that can break down a wide range of pollutants into harmless substances like water, carbon dioxide, and simple salts.

Key Components of AOPs:
1. Hydroxyl Radicals (•OH)
• The core of AOPs is the generation of hydroxyl radicals, which are extremely reactive and capable of oxidizing almost any organic compound.

2. Oxidant Sources
• Hydrogen Peroxide (H₂O₂): Used as a source of hydroxyl radicals when combined with UV light or other catalysts.

• Ozone (O₃): Can generate radicals through reactions with water or catalysts.

• Catalysts: Metal ions (e.g., Fe²⁺ in Fenton’s reaction) or other compounds facilitate radical production.

3. Energy Sources
• Ultraviolet (UV) Light: Often used to activate oxidants like H₂O₂ or O₃.

• Electrical Energy: In processes like plasma discharge or electrochemical AOPs.