Electrochemical and sonoelectrochemical processes applied to the degradation of the endocrine disruptor methyl paraben

Methyl paraben is commonly employed as a preservative in pharmaceutical preparations, personal care products and some processed foods. However, the ester constitutes a potential pollutant in aquatic environments and has been classified as an endocrine disruptor. This study describes the degradation of methyl paraben (100 mg L −1 in 0.05 mol L −1 aqueous potassium sulfate at pH 5.7) by means of an electrochemical process (employing a boron-doped diamond anode) either alone or coupled with sonolysis. Electrolyses were performed at 25, 30 and 35 ± 1 °C during 120 min using applied constant current densities of 10.8 and 21.6 mA cm −2 . The hybrid sonoelectrochemical processes were conducted under similar conditions with the application of ultrasound at a frequency of 20 kHz and a power intensity of 523 W cm −2 . Although mineralization of methyl paraben could be achieved using either process, in comparison with the electrochemical method, the hybrid technique showed a higher mineralization efficiency (around 60 %) with approximately 50 % removal of total organic carbon, thereby confirming the synergistic effect of sonolysis.