Ubiquitous Production of Organosulfates during Treatment of Organic Contaminants with Sulfate Radicals

Oxidation of organic contaminants by sulfate radical (SO4 •–) is becoming more popular for the treatment of hazardous waste sites by in situ chemical oxidation and industrial wastewater by advanced oxidation processes. It is well documented that SO4 •– can produce oxygen-containing transformation products similar to those produced by hydroxyl radical-based treatment processes, but SO4 •– also has the potential to produce organosulfates by radical addition. Experiments conducted with a suite of 23 aromatic and five aliphatic compounds, including several contaminants typically detected at hazardous waste sites, demonstrated the formation of at least one stable sulfate-containing product for 25 of the compounds. These compounds likely exhibit higher mobility in the subsurface due to a lower affinity for surfaces (e.g., aquifer solids and activated carbon) than most other transformation products. Although the health risks associated with organosulfates are still uncertain, some aromatic organosulfates produced in this study (i.e., phenyl sulfate and p-cresyl sulfate) are known to be harmful uremic toxins. Further study of the formation, fate, and toxicity of organosulfates may be necessary before SO4 •–-based treatment processes are more widely employed.