Mechanism of tartaric acid promoting CuO/H2O2 Fenton-like degradation of sarafloxacin

Abstract

Tartaric acid (TA) as an organic assistant was investigated to degrade sarafloxacin (SARA) in an advanced oxidation process (AOP) with CuO catalyst. The promotional effect of TA is to activate H2O2 decomposition to •OH and HO2•/O2•- by accelerating the Cu(II)/Cu(I) redox cycle on the CuO surface while inhibiting 1O2 generation. TA could increase the conversion percentage of H2O2 to •OH from 18.47 % to 46.23 % and decrease the conversion percentage of H2O2 to O2 from 71.98 % to 45.64 % on CuO in 60 min. In addition, TA was further demonstrated to coordinate with the surface Cu(II) by forming Cu(II)-TA, which leads to an acidic environment and exposing more Cu active sites on the surface and releasing Cu2+ into aqueous solution, thus boosts the AOP. Adding TA into the reaction system not only improves the heterogeneous Fenton-like process (HFLP) but also promotes homogeneous Fenton-like process. In the SARA/TA/CuO/H2O2 system, •OH, HO2•/O2•- and 1O2 are the primary oxide species for SARA degradation. Plausible mechanisms for the degradation of TA and SARA were proposed as well.