Electro-peroxone Treatment Of Orange Ⅱ And P-nitrophenol Containing Wastewaters

Electro-peroxone is a novel advanced oxidation technology that has recentlydeveloped by our group for water and wastewater treatment. In the E-peroxonetreatment, an ozone generator was used to generate ozone from pure oxygen. The O2and O3gas mixture from the ozone generator was then sparged into an electrochemicalreactor that had a carbon–polytetrafluorethylene (carbon–PTFE) cathode, which canconvert O2to H2O2effectively. The in-situ generated H2O2then reacted with the spargedO3(i.e., peroxone reaction) to produce OH, which is a very powerful oxidant and candegrade organic pollutants effectively. An azo dye Orange II was selected as modelcompound and its mineralization and decolorization by electro-peroxone (E-peroxone)process were investigated. The E-peroxone process mineralized Orange II much moreeffectively than the O3alone and electrolysis alone. Complete decolorization and95.7%of the initial total organic carbon (TOC) removal was achieved after4and45min of theE-peroxone, respectively. In comparison, only15.3and55.6%of the initial TOC weremineralized after90min of individual electrolysis and ozonation treatments,respectively. In addition to the high efficiency, the E-peroxone process, operatedeffective over a wide range of solution pH (3-10).This work also investigated the degradation of4-nitrophenol (PNP) byelectrolysis, ozonation, E-peroxone, electrolysis combined with ozonation(electrolysis-O3). Electrolysis removed the original PNP completely after6h, however,it generated polymeric by-products accounted to~20%of the initial TOC. Bycomparison, E-peroxone, electrolysis-O3, ozonation processes removed PNP muchfaster (after~30min) and did not produce any amount of detectable polymers.Additionally,98%of initial TOC was mineralization by E-peroxone process after75min,98%by eletrolysis-O3after90min, and58%by ozonation after6h.Results from these two studies indicate that E-peroxone did not produce anysecondary pollutants. But also can provide a very effective and environmentally-friendlyalternative technology for dye wastewater and phenolic compounds treatment.