Electrochemical Degradation of a Commercial Formulation of the Insecticide Pyriproxyfen Using Boron-Doped Diamond Anode

Abstract

Pyriproxyfen (PPF) is a juvenile hormone agonist used in agriculture and in combating Aedes aegypti. In this work, for the first time, a study of electrochemical oxidation (EO) of this insecticide is reported, which involved the degradation of a commercial formulation of PPF on boron-doped diamond (BDD) electrode. pH conditions influenced the process; after 360 min of electrolysis the COD removals were 88.1% (pH 3.0), 78.9% (pH 5.0), 65.5% (pH 7.0), 76.7% (pH 9.0) and 80.0% (pH 11.0). The increase in applied current density favored the COD removal and the S2O82– generation. At 20, 40 and 60 mA cm–2, the COD removal was 88.1%, 90.0% and 91.0% and the S2O82– production was 0.15, 0.26 and 0.35 mmol l–1, respectively. The COD removal process occurred via •OH and other oxidants as S2O82− and SO4–•, and it was more efficient at the lowest current density (20 mA cm–2), which removed 88.1% COD with the lowest energy consumption (25.2 kWh m–3). Chromatographic (GC-MS and IC) data showed that the EO removed 37% PPF and formed short chain carboxylic acids as final organic by-products. EO with DDB seems to be an appropriate approach to be applied to degrade PPF in contaminated environmental samples.