Advanced oxidation processes for the decontamination of heavy metal complexes in aquatic systems: A review

A significant challenge in industrial wastewater treatment is the presence of heavy metal complexes (HMCs) formed when heavy metals interact with organic complexing agents. These HMCs exhibit greater stability compared to free heavy metal ions, making them resistant to degradation and removal via conventional methods. The presence of HMC in wastewater has spurred extensive research into effective removal methods. Conventional wastewater treatment systems, including adsorption, precipitation/electrodeposition, ion exchange, and membrane filtration, often fall short in removing HMCs. In recent years, advanced oxidation processes (AOPs) have emerged as a promising approach for effectively degrading HMCs. AOPs, a class of chemical processes utilizing reactive oxygen species (ROS), effectively degrade organic pollutants and decompose HMCs into readily removable free metal ions. This review provides a quantitative assessment of the viability of AOPs for wastewater detoxification through HMC decomposition. It explores various AOPs used for the removal of HMC from wastewater, highlighting their advantages and limitations. The influence of experimental factors and the mechanisms involved in the removal of HMC by AOPs are also discussed. Finally, the potential applications and challenges of AOPs for wastewater remediation are discussed. This critical review is intended to be a valuable resource for engineers, chemists, and environmental scientists who are involved in the use of AOPs to treat wastewater containing HMC. AOPs are effective in decomposing HMC but expensive and energy intensive. More research is needed to develop new AOPs that are efficient and cost-effective.