UC Berkeley

Oxidation of organic contaminants by sulfate radical (SO₄ ^•-) is becoming more popular for the treatment of hazardous waste sites by in situ chemical oxidation (ISCO) and industrial wastewater by advanced oxidation processes (AOPs). It is well documented that SO₄ ^•- can produce similar oxygen-containing transformation products as 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 5 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, 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 organosulfate formation, fate, and toxicity is needed before SO₄ ^•--based treatment processes are more widely employed.