Electrochemical Degradation of Acetaminophen in the Presence of Different Redox Mediator Systems

摘要

This study focuses on the electrochemical degradation of acetaminophen (AP) in the presence ofindividual redox mediators. The oxidation peaks of Fe(II), Ag(I), and sulfate were detected on a Windsorboron-dopped diamond (BDD) electrode in 1 M Na 2 SO 4 . The AP degradation performance using a singlemediator was in the following order: Ce(IV) (from Ce(SO 4 ) 2 ) > Fe(III) (from Fe(NO 3 ) 3 or FeCl 3 ) > Co(II)(from CoCl 2 ) ≈ Ag(I) (from AgNO 3 ). p-BQ due to AP degradation was observed in 1 M Na 2 SO 4 in thepresence of Ce(IV) and Fe(III), while the former exhibited more and faster p-benzoquinone (p-BQ)generation than the latter. In the presence of individual mediators in 1 M Na 2 SO 4 or NaNO 3 , theperformance of electrochemical AP degradation, p-BQ removal, and TOC mineralization on a DiachemBDD anode occurred in the following order: Fe(III) > Ce(IV) > Fe(II) ≈ Co(II) > Ag(I), but theperformance decreased when replacing Na 2 SO 4 with NaNO 3 as the electrolyte. The Cl 2 /Cl – redoxmediator could also enhance AP degradation and TOC mineralization. The apparent pseudo first-orderrate constants for AP electrochemical degradation in these solutions ranged from 2.92×10 -4 ?4.34×10 -21/s. An Fe(III) dosage of 100 ppm (Fe(III)/AP mole ratio = 2.7) at 0.25 A/cm 2 is suggested for thiselectrochemical process although Fe(III) dosage in the range of 50?500 ppm could be considered. Fe(III)has good potential for use in the elctrochemical advanced oxidation process (EAOP) to significantlyimprove organic pollutant degradation performance.