An innovative approach to the application of electrochemical processes based on the in-situ generation of H2O2 for water treatment

Abstract

This study presents an innovative strategy for the implementation of electrochemical treatment systems based on the in-situ generation of H2O2 targeted at the removal of organic contaminants in aqueous matrices. Unlike the studies based on the continuous application of electric current, in the present work, the electric power supply was interrupted once desired concentrations of H2O2 were accumulated in solutions previously spiked with the contaminant. The accumulated H2O2 was then activated by illuminating the solution with UVC light, which gave rise to the process called UVC/¢-H2O2. The application of current densities of 10 and 25 mA cm−2 for only 10 min led to the efficient production of H2O2 in concentrations ranging from ∼48 to 112 mg L−1, which resulted in the complete degradation of the antibiotic norfloxacin (NOR; 60 μmol L−1) and high mineralization rates in the UVC/¢-H2O2@10 mA cm−2 and UVC/¢-H2O2@25 mA cm−2 processes. Moreover, no residual H2O2 was detected within 90 min of treatment in both conditions. Although similar results in terms of NOR degradation/mineralization were obtained from the application of the UVC/c-H2O2@25 mA cm−2 process (i.e., based on the continuous application of 25 mA cm−2), a significant residual concentration of H2O2 (∼100 mg L−1) was detected after treatment. Noticeably, the application of the UVC/¢-H2O2@25 mA cm−2 method led to ∼26% reduction in overall energy consumed in the mineralization process compared to the conventional system using the continuous application of electric current.