A Study On The Relationship Between The Polarization Characteristics Of Activated Carbon Particle Electrode And The Degradation Of Pollutants In A Three Dimensional Electrochemical Reactor(3DER)

Three-dimensional electrochemical reactor(3DER)is a novel electrochemical wastewater treatment technology by filling the conductive particles into the electrolytic cell of traditional two-dimensional electrolysis.These particles are polarized by the external electric field to form numerous microelectrodes,thus greatly improving the current efficiency and treatment efficiency of the reactor.The performance of the 3DER in wastewater treatment is highly dependent on the polarization of the particles.However,related research on the polarization of particle electrodes in 3DER is very limited until now.In this work,a microprobe device was developed to monitor the polarization potential of activated carbon particles in 3DER;The effects of different reaction conditions(cell voltage,electrolyte concentration,initial pH of electrolytic solution)on particle polarization(particle potential,solution potential,driving force for electrode reaction,induced potential of the particle)were investigated.The correlation among reaction conditions,particle polarization and decolorization rate was analyzed based on statistical method using Acid orange 7(AO7)and Rhodamine B(RhB)dying wastewater as the target pollutants.The results were as follows:(1)The novelty of this work is the development of the microprobe device,comprising platinum wire,calomel electrode,Luggin capillary and salt bridge.By connecting the microprobe device to a multimeter,the potential measurement system for particle electrodes of the 3DER was constructed.The results showed that the developed microprobe device can accurately determine the potential of particle electrodes,facilitating to explore the polarization behavior of particle electrodes in a 3DER.(2)The potential on the same particle electrode was equal everywhere,while the solution potential was different for different locations.Thus,different driving force for electrode reaction appeared at different locations of the particle electrode.The applied voltage significantly affected the driving force of electrode reaction on the particle electrodes,as well as the particle polarization.The concentration of electrolyte and the initial pH of the electrolytic solution showed no significant influence on the driving force of electrode reaction.Under the experimental conditions of this work,both the driving force of electrode reaction and decolorization rate of the contaminants in the 3DER were significantly improved by applying 4 V voltage.This was because that the particle electrodes in 3DER were effectively polarized when the voltage reached 4 V.The particle induced potential further proved that the particle electrodes were effectively polarized at 4 V cell voltage.(3)The decolorization rate of AO7 highly depended on the driving force of particle electrode reaction with the correlation coefficient up to 0.9(95% confidence level).The degradation experiments of two dyes were carried out in a 3DER packed with regular particle electrodes and disordered particle electrode,respectively.The results indicated that the decolorization rate of AO7 in 3DER packed with regular particle electrodes(filling 10 g particle electrodes)was 9.5% higher than that in the other 3DER system.Similarly,the value was 15.8% for RhB(filling 13 g particle electrodes).Based on potential analysis,the polarization of regular particle electrodes in a 3DER was superior than that of disordered particle electrodes.In this work,a microprobe system for measuring the potential of particle electrodes in 3DER was established.The polarization characteristics of particle electrode and their correlations with pollutants degradation were explored.The results were helpful to understand the polarization mechanisms of particle electrodes in 3DER,providing theoretical reference for the optimization of reaction conditions in 3DER.