Humic-Like Substances as Auxiliaries to Enhance Advanced Oxidation Processes

The application of humic-like substances (HLSs) in advanced oxidation processes for wastewater treatment is summarized in this work. HLSs share important characteristics with humic substances, and they can be isolated from different wastes using procedures that are related with their pH-dependent solubility. They are able to generate, upon irradiation, reactive species such as hydroxyl radicals and singlet oxygen or triplet excited states. Although photochemical removal of pollutants can be reached by HLSs, in general, irradiation times are very long. HLSs are good metal-complexing agents, and the Fe-HLS complex is able to participate in (photo)-Fenton-like processes at mild pH, preventing iron deactivation. Finally, novel hybrid materials with environmental applications have been synthesized using HLSs; in some cases, they also contain iron oxides, which allow a better separation but also the ability to drive heterogeneous (photo)-Fenton processes.

Automated summary

This work summarizes the application of humic-like substances (HLSs) in advanced oxidation processes for wastewater treatment. HLSs have important characteristics similar to humic substances and can be isolated from different wastes. They can generate reactive species upon irradiation. Although HLSs can remove pollutants through photochemical processes, the irradiation times are generally long. HLSs also act as good metal-complexing agents and can participate in (photo)-Fenton-like processes at mild pH. Additionally, novel hybrid materials with environmental applications have been synthesized using HLSs.