| Recently,Electrocatalytic Oxidation?ECO?method for treating organic industrial wastewater has been widely used.There are many reasons lead to this result.Firstly,this method can hardly produce toxic and harmful intermediate products.Furthermore,it also has the advantages of simple equipments and environmental-friendly.However,at the same time,Electrocatalytic Oxidation?ECO?method has drawbacks as well.For instance,this technology is still in the laboratory stage.More specifically,it is difficult to be applied on a larger scale due to its high energy consumption.Therefore,at present,the focus of research is to explore new methods which can meet the requirements of low energy consumption and high efficiency.For this report,the main research is to combine pulse power supply with ECO technology to achieve the goal of reducing energy consumption.First of all,the system capacitance was determined by electrochemical test and the optimum duty cycle of pulse power supply was calculated according to the capacitance value.Then the effects of electrolyte,current density and inlet velocity on the pulse electrocatalytic oxidation of organic compounds were investigated.After that,the degradation intermediates were analyzed by UV and GC-MS.What's more,the energy consumption of DC electrocatalytic oxidation and pulse electrocatalytic oxidation were researched as well.Finally,the change rule of pH value in pulse electrocatalytic oxidation process was explored.The specific research contents are as follows:?1?The capacitance of the system was determined by cyclic voltammetry,polarization and electrochemical impedance measurements:the existence of system capacitance was basically determined by CV curve analysis;the exchange current density was 2.82×10-5 mA/cm2 measured by polarization curve and the resistance was calculated to be 0.023?;According to the Bode diagram of electrochemical impedance EIS test,the peak characteristic frequency?*=5.49 Hz was obtained and the capacitance C value was calculated to be about 8.00 F.Finally,combined with on-discharge formula,the on-off time was calculated to be 79 s and 38 s respectively which means the duty cycle was 0.6.?2?IrO2-Ta2O5/Ti electrode was used as the anode and Ti electrode as the cathode.Under the condition of feeding water circularly and pulse power supply?duty cycle is0.6?,the phenol and COD removal rate were explored under the condition of changing electrolyte,current density and inlet water velocity.The experimental results show that when sodium sulfate was used as an electrolyte,current density was 5 mA/cm2,inlet flow rate was 3 L/h,the removal efficiency of COD and phenol were 57%and 100%respectively which was the best point.?3?The energy consumption of water treatment under impulse and direct current conditions were compared and analyzed.The results show that the energy consumption per unit COD treatment and per unit volume wastewater treatment under DC power supply is higher than that under different pulse conditions,and the energy consumption per unit COD treatment and per unit volume wastewater treatment under the same condition is almost 15 and 20 times of that under pulse condition.Obviously,the pulse power supply mode greatly reduces the energy consumption and achieves the effect of energy saving.?4?The variation of solution pH value during pulse electrocatalytic oxidation was investigated.The results show that the exchange of Na+/H+occurs at the solid-liquid interface due to the existence of system capacitance,which makes the solution pH fluctuate up and down.Moreover,because of the particularity of energy storage materials for system capacitors,this rule has been maintained without the influence of other factors.In the presence of organic matter,the acidity accumulation increases and the range of fluctuation decreases gradually.The reason is that the degradation of organic matter produces anionic intermediates.In a word,the degradation efficiency of organic matter is improved because the solution is always in the acidic state. |
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