Improved electrocatalytic degradation of toxic and resistant picric acid with PbO2-ZrO2 anode; New insight into degradation mechanism by a DFT approach

The convergent paired electrochemical degradation of 2,4,6-trinitrophenol (TNP) was studied on a PbO2 anode modified with zirconium dioxide nanoparticles (ZrO2. NPs). The ZrO2. NPs are perfectly able to improve the lifetime of graphite/ss-PbO2-ZrO2 anode and increase its oxygen evolution potential. Using this electrode, we achieved a COD removal efficiency of 87% after 105 min. This study also provides a new insight into the electrodegradation mechanism of TNP and proves that both electrode processes are involved in the degradation of TNP. The important section of this research is to suggest a detailed mechanism for the electrochemical reduction of TNP along with a detailed suggestion of all possible pathways in the oxidation of cathodically produced 2,4,6-triaminophenol (TAP). Accordingly, the convergent paired degradation of TNP involves reduction of TNP at the cathode and oxidation of TAP at the anode. We have also performed DFT calculations to get deeper insights for the degradation mechanism of TNP.