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

Abstract

Oxidation of organic contaminants by sulfate radical (SO 4•− ) 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 SO 4•− can produce oxygen-containing transformation products similar to those produced by hydroxyl radical-based treatment processes, but SO 4•− 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 SO 4•− -based treatment processes are more widely employed.

Boosting Efficiency in Light‐Driven Water Splitting by Dynamic Irradiation through Synchronizing Reaction and Transport Processes**

“…A likely explanation for this behavior is a transport‐limited reaction around the photosensitizer: The reaction of PS with S 2 O 8 2− produces a sulfate ion as well as a sulfate radical, which is an extremely potent oxidant capable of oxidizing even aromatic structures [32–34] . This sulfate radical is the likely cause for the oxidative ligand substitution proposed as a degradation mechanism (see Figure 4).…”

Second-Order Kinetic Rate Coefficients for the Aqueous-Phase Sulfate Radical (SO4•–) Oxidation of Some Atmospherically Relevant Organic Compounds

“…The C 3 –C 5 acids under study did not have significantly different reactivities with SO 4 •– compared to their carboxylates within the uncertainties of the analyses. Of particular interest may be the reaction of 1,2-DHI with SO 4 •– , which is able to form surface-active organosulfates, 8 − 10 , 50 or the potential reaction of MT-4-S with SO 4 •– to propagate sulfur radicals. 21 For other compounds, the k SO4 rates determined here may help improve the understanding of aerosol mass loss, which may be underpredicted in current models.…”

“… 1 − 3 The oxidation of reactive carbon emissions in the aqueous phases of aerosols, fogs, and clouds initiated by hydroxyl (OH) radicals, nitrate (NO 3 ) radicals, and the sulfate anion radical (SO 4 •– ) has been reviewed previously (refs ( 4 − 6 ) and references therein). SO 4 •– radicals have been recognized as a potentially important source of surface-active organosulfates (OSs) in the environment, 7 − 10 which can modify aerosol cloud interactions. 11 , 12 A large variety of OSs have been identified in both field and laboratory studies, several of which are proposed to only be formed from SO 4 •– radicals.…”

Investigation of ICP‐MS/MS for total sulfur quantification in freshwater dissolved organic matter

“…Direct quantification of sulfur in freshwater DOM creates an opportunity for online coupling with other methods, such as liquid chromatography. This hyphenated technique could quantify sulfur in different fractions of DOM to determine which fractions are most likely to interact with trace and heavy metals or to isolate specific organosulfur compounds that are byproducts of waste treatment processes (Van Buren et al, 2021). Solid phase extraction (SPE) is a simple, convenient, and fast method for the isolation of DOM from fresh and saltwater (Dittmar et al, 2008;Raeke et al, 2016).…”

“…Reduced sulfur is readily incorporated into dissolved organic matter (DOM) and makes up 0.5-3% of freshwater DOM by weight (Kneer et al, 2020;Manceau & Nagy, 2012;Poulin, Ryan, et al, 2017;Ravichandran, 2004). Sulfide produced during microbial sulfate reduction in aquatic environments is integrated into DOM by abiotic substitution and/or radical addition to functional groups containing unsaturated carbon-carbon bonds (Graham et al, 2017;Heitmann & Blodau, 2006;Hoffmann et al, 2012;Perlinger et al, 2002;Sleighter et al, 2014;Van Buren et al, 2021;Yu et al, 2015). Products of sulfur addition, including highly reduced exocyclic species (e.g., thiols and thioesters) and moderately reduced heterocyclic species (e.g., thiophenes) as well as some oxidized species (e.g., sulfoxides, sulfones, sulfonates, and sulfate esters), are found in the surface water, sediment, and porewater of both marine and freshwater environments (Graham et al, 2017;Hoffmann et al, 2012;Poulin, Ryan, et al, 2017).…”