Common Anode Eletro-fenton System To Treat MTBE Contaminated Ground Water

Based on Electro-Fenton theory,the paper was to build a common anode Electro-Fenton system for MTBE degradation in groundwater.Comparing the new Fenton system with traditional one,demonstrating the advantages of common anode Electro-Fenton system for automatically generating H O,? OH,Fe without any chemical additives,revealed Fe accumulation mechanism and kinetics,and the industrialized potential of the common anode Electro-Fenton system.The common anode Electro-Fenton experimental system,single Anode and Cathode Electro-Fenton experimental system were introduced separately in to different trough accompanied with MTBE simulated groundwater,running under different experimental conditions,test the residue MTBE in the water separately.The testing results showed that the common anode Electro-Fenton system enable to adjust the current ratio passing through both iron cathode and MMO cathode due to its unique electrode and current setting: MMO Anode(Titanium Coating Inert Anode)?Iron Cathode?MMO Cathode,connecting to dual DC power supply.The system itself generates the electro-fenton reaction to produce ? OH to degrade MTBE without external iron source or H O added.In addition,the accumulation of ? OH conforms to the Quasi-Zero Order Reaction Kinetics,and the accumulation rate constant of ? OH showed a good linear relationship with MTBE degradation rate constant.The accumulation of Fe conforms to First-Order Kinetics.A small scale of common anode Electro-Fenton experimental system was built for MTBE simulated contaminated groundwater remediation: put 3 electrodes as described above into MTBE simulated groundwater,water electrolyzes to produce O at MMO anode and produce H at Iron and MMO cathode,while Fe is produced by chemical corrosion at Iron cathode.In the system,palladium catalyst(Pd/Al O,5%wt)which help to produce H O through catalytic reaction was placed in the system.Because the current imbalance between MMO anode and Iron cathode,form a partial acid condition near the cathode to ensure the system running under self-sufficient fenton reaction.Different current ratios,pole spacing,MTBE initial concentration and catalyst concentration conditions were set respectively to study the effects of commen anode electro-fenton system on water quality(pH,DO,ORP)and MTBE degradation efficiency.With the orthogonal experiment of the above four conditions,the optimal trough experimental conditions were C initial MTBE : 40 mg/L,the current ratio: 500:300,the pole spacing between MMO anode and iron cathode: 24 mm,C catalyst:1 g/L,and the MTBE removal rate: 81.2%.A column common anode Electro-Fenton experiment equipment was designed and built based on optimized research results.The equipment was applied to the simulation scenarios of different groundwater conditions,such as groundwater flow rate,pH,oxygen-containing,ions and inorganic salts etc.,to investigate the changes of groundwater quality and efficiency of MTBE degradation.In the column common anode Electro-Fenton experiment,the MTBE removal rate was above 65% when the groundwater flow rate laying among 3-6 mL/min,the flow rate less than 3 mL/min or the flow rate bigger tan 6 mL/min would significantly influence the pH and ORP in the water system,which was reflected as the degradation efficiency of the Electro-Fenton reaction;the MTBE removal rate was above 75% while groundwater's pH was at 7;the low oxygen content in groundwater did matter in terms of the pH and ORP of the system other than the MTBE removal rate;the common anode Electro-Fenton system suffered a significantly lower MTBE removal rate on condition of Ca concentration above 0.01mol/L.Cl quenched the hydroxyl radicals,thereby decreasing MTBE degradation rate.Based on the laboratory data,an MTBE contaminated groundwater sample from a Shanghai gas station was applied to the column common anode ElectroFenton device,in which the MTBE removal rate met requirement of relevant groundwater regulations,and the content of MTBE was lowered to 0.01mg/L.The device can be run automatically in long time,easy to operate and management,indicating the study was of high practical value.