Determination of H2O2 by MnO2 modified screen printed carbon electrode during Fenton and visible light-assisted photo-Fenton based removal of acetamiprid from water

In this work, the applicability of screen printed carbon electrode bulk modified with MnO2 as a mediator was investigated for hydrodynamic chronoamperometric determination of the H2O2 content during the Fenton (Fe2+, H2O2) and the catalytic, visible light-assisted, photo-Fenton (Fe2+, H2O2, hv) based removal of the worldwide used neonicotinoid insecticide acetamiprid which has a pyridine ring and a cyano-imine group in its basic skeleton. For the optimisation of the analytical method cyclic voltammetric, differential pulse voltammetric and hydrodynamic chronoamperometric experiments were performed in model solutions containing the phosphate buffer supporting electrolyte pH 7.5, H2O2, and/or Fe2+ and acetamiprid. Under optimized conditions at the working potential of 0.40 V vs. saturated calomel electrode in the slightly alkaline supporting electrolyte, electrocatalytic hydrodynamic chronoamperometric determination of H2O2 showed a linear dynamic range from 0.01-124 mM, and the relative standard deviation did not exceed 42%. In the investigated samples (after appropriate pH adjustment, filtering, and storage of the deep-frozen sample with defrosting immediately before the measurements) the H2O2 contents were determined from the hydrodynamic chronoamperometric curves by the standard addition method. Parallel HPLC-DAD measurements were performed to monitor the concentration/removal of acetamiprid. In the case of the photo-Fenton process (initial concentrations: 0.31; 2.0 and 3.0 mM of acetamiprid, Fe2+ and H2O2, respectively) after 10 min of irradiation H2O2 was consumed, while during the Fenton process acetamiprid was removed after 20 min of treatment and around 10% of the initial concentration of the H2O2 remained still unused. (C) 2015 Elsevier B.V. All rights reserved.