Degradation of N,N-diethyl-m-toluamid (DEET) on lead dioxide electrodes in different environmental aqueous matrixes

Abstract

This study investigates the electrochemical degradation of N,N-diethyl-m-toluamide (DEET) on PbO₂ and Bi-PbO₂ anodes. The difference in electrode crystalline structure was responsible for the better DEET degradation and TOC removal on PbO₂ than on Bi-PbO₂. In 1 M Na₂SO₄, the degradation efficiency and apparent rate constant (k_app) of DEET oxidation on PbO₂ increased with the increase in current density or temperature (activation energy = 24.4 kJ mol⁻¹). The k_app values in DEET-spiked environmental matrixes (municipal wastewater treatment plant secondary effluent (MWTPSE), groundwater (GW), and river water (RW)) were the same (6.05 × 10⁻⁴ s⁻¹), but significantly smaller than that in 1 M Na₂SO₄ (2.23 × 10⁻³ s⁻¹). The TOC removal efficiency was better in MWTPSE than in RW and GW; however, the mineralization current efficiencies in MWTPSE and RW were similar but higher than that in GW. During electrolysis, the aromaticity was lower in GW than in RW.

Keywords:

• Aromaticity
• electrochemical degradation
• environmental matrix N
• N-diethyl-m-toluamide (DEET)
• PbO₂ anode

Funding

The authors thank the Ministry of Science and Technology (previously National Science Council) of Taiwan for financial support of this research under contract nos. NSC-102-2221-E-020-001-MY3 and NSC-102-2221-E-020-006-MY3.