Insight into reactive oxygen species and synergistic mechanism in Fenton-like system using Cu(0) and Fe(III) as the activator

Abstract

Zero-valent copper (Cu(0))-triggered hydrogen peroxide (Cu(0)/H2O2) process was used to eliminate and mineralize contamination, while its oxidation efficacy was limited by the reaction of Cu(I) with O2. In this study, ferric ion (Fe(III)) was spiked into the Cu(0)/H2O2 (Fe(III)/Cu(0)/H2O2) system, and the degradation rate of paracetamol decreased from 24.9% to 95.4%. In the Fe(III)/Cu(0)/H2O2 system, the reaction of Cu(0) and Cu(I) with Fe(III) expedited the conversion from Fe(III) to Fe(II). The reaction of Cu(I) with O2 was weakened by the competition reaction between Cu(I) and Fe(III), promoting the generation of reactive oxygen species and increasing the utilization of Cu(0). The main reactive oxygen species for pH 4.0 was •OH and Fe(IV) with the contribution rate of •OH and Fe(IV) being 92.3% and 7.7%, but the dominant reactive oxygen species at pH 3.0 was only •OH in the Fe(III)/Cu(0)/H2O2 process. Especially, the contribution of Fe(IV) rose and the contribution of •OH decreased, when the concentrations of 20–80 μmol/L Fe(III), 0.05–0.3 g/L Cu(0) and 50–300 μmol/L H2O2 incremented. In the Fe(III)/Cu(0)/H2O2 process.After we increased the pH of end solution to 7.0/7.5/8.0 and leaching, the total copper in reaction solution was under 6.4/3.3/1.5 μmol/L. In addition, Ni(II) (57.7%), Fe(II) (100%) and Mn(II) (72.4%) obviously enhanced the degradation of paracetamol in the Cu(0)/H2O2 process.