Activation of peracetic acid by RuO2/MWCNTs to degrade sulfamethoxazole at neutral condition

Abstract

• MWCNTs supported RuO 2 catalysts were synthesized. • RM can effectively activate PAA under neutral pH. • SMX was oxidized by CH 3 C(O)O· and CH 3 C(O)OO· in the RM/PAA system. • The electron transfer of ≡Ru 3+ /≡Ru 4+ involved in the PAA activation. Peracetic acid (PAA) as an emerging disinfectant has raised extensive concern due to its high oxidation capacity and low byproducts formation potential. In this work, RuO 2 supported multi-walled carbon nanotube (MWCNTs) was synthesized and applied to activate PAA to degrade sulfamethoxazole (SMX). PAA could be effectively activated by RuO 2 /MWCNTs (RM). Increasing RM loadings (0.03–0.3 g/L) or PAA dosages (0.25–1.5 mM) generally enhanced the degradation efficiency, the excellent performance in SMX degradation (100%) was achieved at 1 mM PAA, 0.2 g/L RM and neutral conditions. Electron paramagnetic resonance (EPR) techniques and radical scavenging experiments indicated acetylperoxy radical (CH 3 C(O)OO·) and acetoxyl radical (CH 3 C(O)O·) as the major reactive radicals responsible for SMX degradation. X-ray photoelectron spectroscopy (XPS) analysis indicated that the electron transfer of ≡Ru 3+ /≡Ru 4+ involved in the PAA activation. The effect of water matrices was also investigated, HCO 3 – and natural organic matter (NOM) slightly inhibited SMX degradation, while Cl - had little impact on SMX degradation. For the reusability of RM, the SMX removal was still achieved 90% after three consecutive tests. This work provides the potential application of RM/PAA in destructing emerging pollutants.