Improved degradation of iohexol using electro-enhanced activation of persulfate by a CuxO-loaded carbon felt with carbon nanotubes as an interlayer

Li, H.X.; Li, Y.; Wang, C.B.; Han, C.X.; Xu, K.F.; Zhang, Z.W.; Zhong, Q.; Shi, K.P.; Xu, Z.; Yang, S.G.; Li, S.Y.; He, H.; Song, H.O.*; Zhang, S.P.*

Abstract

  Persulfate (PS) activation by means of transition metals has been extensively applied to eliminate persistent organic pollutants, but the slow rate of metal redox cycling between high-valence and low-valence states inhibits the degradation reaction. Here, a CuxO-loaded carbon felt with carboxylated multi-walled carbon nanotubes (MWCNT-COOH) as an interlayer (CuxO/CNT/CF) has been successfully prepared. This assembly was then employed in a process of peroxymonosulfate (PMS) activation with the assistance of an electric field (CuxO/CNT/CF-PMS-EC). PMS could be effectively activated by the electrically enhanced CuxO/CNT/CF due to faster metal redox cycling, and the system could be applied over a broad pH range (3.0–11.0). The degradation efficiency of iohexol (IOH) could reach 100% within 25 min, and around 62.7% of total organic carbon (TOC) was removed within 120 min in the CuxO/CNT/CF-PMS-EC system. Both non-radical (1O2)- and radical-mediated (·SO4-, ·O2-, and ·OH) PS activation are involved in the degradation process. According to the results of DFT calculations and LC-MS, the degradation of IOH involves deiodination, amide hydrolysis, amine oxidation, C-OH oxidation, addition of -OH, hydrogen abstraction, and elimination reactions. The present study shows electrocatalysis coupled with transition-metal-activated PS to be a highly efficient technique for the removal of iodinated contrast media (ICMs).

原文链接：https://www.sciencedirect.com/science/article/abs/pii/S1383586623002447