Perfluorooctanoic Acid (PFOA) Incorporated into Iron Particles Promoted the Formation of Disinfection Byproducts under Drinking Water Conditions

Abstract

Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant that is frequently detected throughout the drinking water supply system. Here, we first found that PFOA could significantly increase the formation of disinfection byproducts (DBPs) in unlined iron pipes (UIPs) during the distribution process. The increased DBPs were not due to the reaction of PFOA itself with free chlorine, but the in situ formed Fe–PFOA complex played a key role. Notably, PFOA could enhance iron release from UIPs and was greatly incorporated into the iron particles to form Fe–PFOA complex. The •OH generated by the Fe–PFOA heterogeneous reaction could break large dissolved organic matter into small molecules that had higher reactivity with chlorine. In addition, DBP precursors with more aromatic structures were favorable for forming strong Fe−π interactions with Fe–PFOA complex, resulting in more •OH for the formation of aromatic DBPs. The cytotoxicity test showed that the viability of cells exposed to DBPs from UIPs with 100 ng/L PFOA was 46.9%, while that without PFOA was 67.91%. Overall, this study provided a new perspective on the risk of PFOA, with a focus not on PFOA itself but on its potential to promote DBP-associated toxicity in iron-based drinking water distribution pipes.

Effects of Iron Particles on Chlorine Decay and DBP Removal during Boiling Drinking Water

“…For DBP formation, iron oxides have a catalytic effect with the formation of • OH to break large natural organic matter (NOM) compounds into small molecules with higher reactivity . The formation of Fe-perfluorooctanoic acid complex has been found to have an even stronger catalytic effect for DBP formation than single iron crystals . Moreover, iron particles could release NOM during boiling, which further affects DBP formation .…”

“…18 The formation of Fe-perfluorooctanoic acid complex has been found to have an even stronger catalytic effect for DBP formation than single iron crystals. 19 Moreover, iron particles could release NOM during boiling, which further affects DBP formation. 20 Previous research has found that the concentrations of aromatic DBPs during boiling generally followed an increasing trend due to decarboxylation of polycarboxylic precursors in chlorinated tap water.…”

PFOA Increases Microbial Risk by Promoting Iron Release and Weakening Biofilm Adhesion in Unlined Iron Drinking Water Pipes

“…With carboxyl groups, PFOA can bind with metal ions through complexation and guide the formation of composite particles . In our previous study, we found that PFOA itself could not react with chlorine to generate disinfection byproducts (DBPs), but DBP precursors with aromatic structures were favorable for forming strong Fe–π interactions with the Fe–PFOA complex, resulting in more • OH for the formation of toxic aromatic DBPs, which provided a new perspective on the risk of PFOA …”

“…5 In our previous study, we found that PFOA itself could not react with chlorine to generate disinfection byproducts (DBPs), but DBP precursors with aromatic structures were favorable for forming strong Fe−π interactions with the Fe−PFOA complex, resulting in more • OH for the formation of toxic aromatic DBPs, which provided a new perspective on the risk of PFOA. 6 In DWDS, a biofilm could be formed on the interface of the pipe wall. Self-produced extracellular polymeric substance (EPS) could accumulate organics and inorganics to form a biofilm matrix by providing viscous forces between bacteria and the pipe wall.…”

Water Analysis: Emerging Contaminants and Current Issues

“…Zhuang et al reported that nitrate promotes the formation of toxic N-DBPs in corroded iron drinking water pipes. 107 Results suggested that a Fe−O−C bond forms between iron corrosion products and NOM, which promotes electron transfer for nitrogen transformation with pyrrolic nitrogen as the intermediate species. Density functional theory (DFT) calculations supported this proposed mechanism.…”