Water Vapor Condensation Triggers Simultaneous Oxidation and Hydrolysis of Organic Pollutants on Iron Mineral Surfaces

Increasing worldwide contamination with organic chemical compounds is a paramount environmental challenge facing humanity. Once they enter nature, pollutants undergo transformative processes that critically shape their environmental impacts and associated risks. This research unveils previously overlooked yet widespread pathways for the transformations of organic pollutants triggered by water vapor condensation, leading to spontaneous oxidation and hydrolysis of organic pollutants. These transformations exhibit variability through either sequential or parallel hydrolysis and oxidation, contingent upon the functional groups within the organic pollutants. For instance, acetylsalicylic acid on the goethite surface underwent sequential hydrolysis and oxidation that first hydrolyzed to salicylic acid followed by hydroxylation oxidation of the benzene moiety driven by the hydroxyl radical (•OH). In contrast, chloramphenicol underwent parallel oxidation and hydrolysis, forming hydroxylated chloramphenicol and 2-amino-1-(4-nitrophenyl)-1,3-propanediol, respectively. The spontaneous oxidation and hydrolysis occurred consistently on three naturally abundant iron minerals with the key factors being •OH production capacity and surface binding strength. Given the widespread presence of iron minerals on Earth's surface, these spontaneous transformation paths could play a role in the fate and risks of organic pollutants of health concerns.