Directed transformation of glyphosate to orthophosphate in EAOP based on Ti/SnO/PbO 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) (PO), 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/SnO/PbO-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/SnO/PbO 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 O isotope labelling technique in this study. Therefore, the synergistic effect of ·OH and high-valent Pb enhanced the Gly degradation and directed generation of PO through the cleavage of C-P bond in the EAOP system based on Ti/SnO/PbO 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).