In situ electrochemically generated peroxymonophosphoric acid as an oxidant for the effective removal of gaseous acetaldehyde

- Undivided cell evidenced to prepare peroxymonophosphoric acid.
- Ti cathode favored to prepare high concentration of peroxymonophosphoric acid.
- High concentration of peroxymonophosphoric at equal cathode size seems to be influence of OH.
- With the 1.71% current efficiency, 30 ppm of acetaldehyde was removed successfully.

Peroxymonophosphate in salt form has a wide range of applications. In this study, peroxymonophosphoric acid (PMPA) was generated in situ in an undivided electrolytic cell (single cell) and applied to the removal of acetaldehyde, a model air pollutant. PMPA was characterized by titration methods and 31P-nuclear magnetic resonance spectroscopy. The generation of PMPA was initially optimized using boron-doped diamond as the anode and different cathode materials (Pt-coated Ti, DSA, Ti, and Cu) in constant current mode. Of the cathodes assessed, the maximum concentration of PMPA (6 mM) was achieved from an initial concentration of 1 M H3PO4 using the Ti cathode. This study examined the influence of the applied current density, temperature, and initial H3PO4 concentration. A higher PMPA concentration was produced using an anode and cathode with equal sizes than that with smaller sized cathodes. This shows that a larger cathode produces a greater number of OH, which is responsible for the production of PMPA. Under optimized cell parameters (electro-scrubbing), the oxidative removal efficiency of acetaldehyde from a wet-scrubbing column with the online production of PMPA was approximately 95% for a 30 ppm inlet concentration. The removal of 30 ppm of acetaldehyde required only 6 mM of electrogenerated PMPA, which makes it competitive with the high concentration metal ion mediator that is used to remove the same concentration of acetaldehyde.

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