Advanced oxidation processes and nanomaterials -a review

Water related problems are expected to further increase considerably due to climate changes and population growth. Conventional wastewater treatment can be either a physical, chemical, and/or biological processes, or in some cases a combination of these operations. Current wastewater treatment technologies are deemed ineffective in the complete removal of pollutants, particularly organic matter. In many cases, these organic compounds are resistant to conventional treatment methods, thus creating the necessity for secondary treatment. Advanced Oxidation Processes (AOPs) are chemical oxidation processes that use powerful transitory species such as hydroxyl radicals and sulphate radicals. These species can be generated from water using energy for instance solar energy, electrical energy, sound energy etc or simply by chemicals like H2O2, ozone etc with or without the use of an appropriate catalyst. In many such methods, nanomaterials have been effectively used as catalysts for the generation of the transitory species. The large-scale commercialization of AOPs can lead to reduction of cost favorable to environmental applications as AOPs are based on physicochemical processes that produce intense changes in the structure of chemical species. The majority of AOPs can be applied to the remediation and detoxification of low or medium volumes of waters. This review summarises the major Advanced Oxidation Processes reported in recent literature with emphasis on the latest advances in the use of nanomaterials employed in various processes.