A synergistic system of electrocatalytic-anode/α-MnO2/peroxymonosulfate for removing combined pollution of tetracycline and Cr(VI)

A novel electrocatalytic anode (ECA)/alpha-MnO2/peroxymonosulfate (PMS) synergistic system was developed and evaluated for the removal of combined tetracycline (TC) and hexavalent chromium (Cr(VI)) pollution from waste waters. The factors affecting the efficiency of the removal of the combined pollutants, such as the synthesis time of the electrode, the amounts of raw materials, the PMS dose, the voltage, the initial pH and the coexisting ions were investigated. The breakdown products of PMS in the ECA/alpha-MnO2/PMS system improved the conductivity of the solution and the electrical current promoted the conversion of the valence state of Mn ions, resulting in a synergistic effect between the ECA and PMS activation processes, which improved the efficiency of removal of TC. The cathode chamber was fully utilized to simultaneously reduce Cr(VI). Synergistic effects occur in the ECA/ alpha-MnO2/PMS system in appropriate ranges of the voltage or PMS dose, although the efficiency of the removal of TC depends mainly on the electrical current in the system. Both hydroxyl (center dot OH) and sulfate (SO4 center dot- ) radicals played important parts in the degradation of TC. The main degradation products of TC were identified and degradation pathways proposed. The synergistic effects between the ECA process and a Fenton-like process was studied, providing a new approach for the study of electro-Fenton technology and the removal of combinations of TC and Cr(VI) from waste waters.

Automated summary

The novel ECA/alpha-MnO2/PMS system showed synergistic effects in the removal of TC and Cr(VI), with the breakdown products of PMS enhancing the solution conductivity and electrical current promoting the conversion of Mn ions. The efficiency of TC removal mainly depends on the electrical current, while synergistic effects occur within appropriate ranges of voltage or PMS dose. Both hydroxyl and sulfate radicals play important roles in TC degradation, with identified degradation products and proposed pathways. The study also explored the synergistic effects between ECA process and a Fenton-like process, offering a new approach for the study of electro-Fenton technology and removal of TC and Cr(VI) from waste waters.