Formation of Hydroxyl Radicals in Advanced Oxidation Processes for the Degradation of Contaminated Organic Matter

Organic compounds in different solutions have caused several pollution problems to the environment and even affected human health. Advanced Oxidation Processes (AOPs) have been effectively used in the decontamination of these types of compounds. Distinct reactive oxygen species (ROS) have been proposed to explain the degradation or mineralization of contaminating organic matter. ROS, such as free radicals (e.g., .OH), superoxide (e.g., .O<sub>2</sub> <sup>−</sup>), and peroxides (e.g., H<sub>2</sub>O<sub>2</sub>), are capable of modifying the chemical structure of organic matter and consequently degrade or mineralize it. In this review, the formation of hydroxyl radicals in each AOP, as in a hybrid process, and the methods for quantifying and determining this type of radical are discussed.