Photochemical degradation, also known as photodegradation, is a process in which chemical compounds are broken down by the absorption of light energy, typically from sunlight. This process can be harnessed to reduce the concentration of toxic pollutants such as pesticides, herbicides, and industrial chemicals in aquatic environments. Here are some strategies to achieve this:1. Solar photocatalytic treatment: In this method, a photocatalyst such as titanium dioxide, TiO2 is added to the contaminated water. When exposed to sunlight, the photocatalyst generates reactive oxygen species ROS that can break down the toxic pollutants into less harmful compounds. This method has been successfully applied to degrade various organic pollutants, including pesticides and herbicides.2. Floating photocatalytic materials: To increase the exposure of pollutants to sunlight, floating photocatalytic materials can be used. These materials can be made of porous materials impregnated with photocatalysts or photocatalytic nanoparticles embedded in a floating matrix. The floating materials can be placed on the surface of the contaminated water body, allowing for efficient sunlight absorption and pollutant degradation.3. Photo-Fenton process: The Fenton process involves the use of iron salts and hydrogen peroxide to generate hydroxyl radicals, which are highly reactive and can degrade a wide range of pollutants. By combining this process with sunlight exposure, the photo-Fenton process can be more efficient in breaking down toxic pollutants in aquatic environments.4. Sensitized photodegradation: In this approach, a sensitizer molecule is added to the contaminated water, which absorbs sunlight and transfers the energy to the pollutant molecules, initiating their degradation. This method can be particularly useful for pollutants that do not readily absorb sunlight.5. Enhancing natural photodegradation: Some pollutants can undergo photodegradation without the need for added catalysts or sensitizers. To enhance the natural photodegradation process, measures can be taken to increase sunlight exposure in the contaminated water body, such as removing shading structures or vegetation and improving water circulation.6. Combined treatment methods: Photochemical degradation can be combined with other water treatment methods, such as biological treatment or adsorption, to improve the overall efficiency of pollutant removal.By implementing these strategies, photochemical degradation can be effectively used to reduce the concentration of toxic pollutants in aquatic environments, helping to protect ecosystems and human health.