Directed transformation of glyphosate to orthophosphate in EAOP based on Ti/SnO2/PbO2 anode: First unraveling the role of high-valent Pb in various reactive oxygen species.

The discharge of wastewater containing non-reactive phosphorus (NRPs), which does not exist in the form of P(V) (PO43-), poses significant environmental risks and phosphorus loss. In this study, electrochemical advanced oxidation process (EAOP) based twenty pairs of electrodes is used to simultaneously achieve the pollution-reducing and targeted conversion of NRPs to P(V). Significantly, EAOP driven by Ti/SnO2/PbO2-Ti plate electrode pair achieved more than five-fold of glyphosate (Gly) removal with only 16 %-56 % of energy consumption compared with that in other anode-based EAOP systems. Usually, Ti/SnO2/PbO2 as a typical non-active anode is considered to produce ·OH as the main active species. Surprisingly, the high-valent Pb was also identified as a key active species through PMSO probe experiment combined with 18O isotope labelling technique in this study. Therefore, the synergistic effect of ·OH and high-valent Pb enhanced the Gly degradation and directed generation of PO43- through the cleavage of C-P bond in the EAOP system based on Ti/SnO2/PbO2 anode. The work provides promising electrodes and insights for identification of reactive species and mechanism in EAOP system to remove NRPs contaminants and targeted conversion to P(V).