Insights into bicarbonate enhanced heterogeneous Fenton catalyzed by Co/Cu/zeolite for degradation of rhodamine B

Most of previous studies proved bicarbonate (HCO3-) was free radical scavenger in advanced oxidation processes, however, in this study, the positive influence of HCO3- was confirmed in heterogeneous Fenton. The results showed that the degradation efficiency of Rhodamine B increased from 13.7% to 95.3% by adding appropriate concentration of HCO3-, and the zeolite supported Co and Cu oxides (Co/Cu/zeolite) could catalyze the HCO3- enhanced Fenton process. The response surface method was employed to optimize the concentration of HCO3- needed in the heterogeneous Fenton system. Radicals quenching results showed that 1O2 and O2 center dot-rather than center dot OH played important roles in the degradation of Rhodamine B. Mechanism studies indicated that carbonate radical (CO3 center dot-) was the key intermediate in the formation of 1O2 and O2 center dot-, and CO3 center dot-could be generated through the reaction between HCO3- and center dot OH. In addition, peroxymonocarbonate (HCO4 -), which further produced CO3 center dot-, was also generated in the bicarbonate enhancement system. The electron transfer between Cu and Co promoted the heterogeneous Fenton process in generating center dot OH that reacted with HCO3-, or catalyzed HCO4- to generate CO3 center dot-.