Study On The Electro-catalytic Oxidation Degradation Of Organic Wastewater With Three-dimensional Electrodes

With the rapid development of society, human beings are sufferingfrom the damage of serious environmental problems. Water pollution hasbecome the focus of environmental pollution. Azo dyes are in the80%percent of dyes, leading to the higher chroma, higher concentration oforganics of the water and the difficulty to degradate which results inserious environmental pollution. In recent years, electrochemical catalyticoxidation method can be used to degradate the non-biodegradablewastewater without adding the oxidant, and with small volume of theequipment to operate simple. Because of small ratio of electrode surface'sarea and volume, two-dimensional electrodes cause low current efficiencyand poor effect of degradation. However, the current efficiency can beincreased by three-dimensional electrodes which provide higher ratio ofelectrode surface's area and volume. Therefore, the effect of degradation can be improved greatly and paid more attention by researchers.The degradation of azo dye wastewater such as o-chloronitrobenzene,o-chloroaniline, azobenzene cathode solution was experimentallyinvestigated using three-dimensional electrodes reactor with granularactivated carbon as the particle electrode, graphite as the anode, andstainless steel plates as the cathode. The effects of concentration ofsolution and electrolyte, pH value, voltage, particle electrode dose,anode-cathode distance, electrolysis time on degradation of concentrationand chemical oxygen demand (COD) of azo dye wastewater wereanalyzed to determine the optimum operating conditions. Because of poorbiodegradability of azobenzene cathode solution, the effect of degradationwas not so well only by using three-dimensional electrodes reactor.Therefore, the azobenzene cathode solution was treated bythree-dimensional electrodes reactor combining activated carbonadsorption, power ultrasonic and aeration methods. The degradation ofazo dye wastewater through the oxidation progress had been monitoredby UV–visible absorption, and high performance liquidchromatographic(HPLC) measurements. Activated carbon was used asparticle electrode of three-dimensional electrodes. The electrochemicalstability of activated carbon for degradation of o-chloronitrobenzene ando-chloroaniline solutions were tested by doing repeat cyclic experiments.Meanwhile, the kinetics of COD removal of o-chloronitrobenzene solution with reaction time was investigated in the experiments.The results showed, at the optimum conditions, the degradationefficiency and COD removal of o-chloronitrobenzene solution reached99.7%and98.5%, respectively. After40repeat cyclic experiments, theCOD removal of o-chloronitrobenzene solution was94.4%; Thedegradation efficiency and COD removal of o-chloroaniline solutionachieved99.0%and97.5%, respectively. After40repeat cyclicexperiments, the COD removal of o-chloroaniline solution was93.9%;The COD removal of azobenzene cathode solution was73.5%only byusing three-dimensional electrodes reactor. When combiningthree-dimensional electrodes reactor with power ultrasonic method, TheCOD removal of azobenzene cathode solution arrived at77.4%.