| With the continuous improvement of modernization,the production and discharge of waste water,waste gas and solid waste in industrial production and production processes are increasing,and the problem of heavy metal pollution in soil is becoming increasingly prominent.Soil remediation technologies mainly include chemical oxidation technique,biotechnology,and electrokinetic remediation(EKR).Electxokinetic remediation is widely used in in-situ remediation of soil heavy metal pollution because of its low investment,easy accessibility,environmental friendliness and less secondary pollution[1].However,there are still some problems such as low removal efficiency of pollutants and large energy consumption in practical application of electrokinetic remediation.Based on the synthesis and properties of polyaniline/nonwoven(PANI/NF)composites,PANI auxiliary electrodes were prepared and applied to the electrokinetic remediation of heavy metal contaminated soils.The main-auxiliary electrodes system was repaired in the soil with chromium pollution.The effectiveness of the migration behavior and removal mechanism were studied.The main-auxiliary electrodes system based on polyaniline auxiliary electrode was optimized by combining energy consumption and remediation efficiency analysis.In this study,the removal mechanism of PANI/NF composites for hexavalent chromium was revealed by the morphology analysis,infrared characterization and adsorption characteristics of the synthesized PANI/NF composites in chromium aqueous solution.Through the study on the current,pH,conductivity and remediation effect of soil during conventional electrokinetic remediation and multi-electrodes electrokinetic remediation,the role of auxiliary electrode in the multi-electrodes system and its influence on pollutant removal were analyzed.Contribution to the removal of contaminants.The electrokinetic remediation of the main-auxiliary multi-electrode system was optimized by comparing the energy consumption and repair efficiency of the electrokinetic remediation experiment with multiple configurations of the auxiliary electrode.The experimental results show that PANI is successfully loaded onto the surface of the carrner maternal nonwoven fabric.In an aqueous solution of pH 6,it achieves a maximum removal rate of 82%.So it is a good adsorbent for heavy metal chromium.In addition,the ability of PANI/NF composites to remove Cr(?)is greatly affected by pH.The study also showed that the removal rate is the highest at pH 2 and the removal effect of Cr(?)gradually decreases with the increasing of pH.In the electrokinetic remediation experiment,under the experimental conditions(EK2)where the anode and cathode are placed with PANI auxiliary electrode,the removal rate of Cr(?)can reach 60%,which is 20%higher than the traditional electrokinetic remediation(EK1).The initial current can reach about 62mA,which is 5 times higher than the traditional electrokinetic remediation.In the multi-electrode system optimization,the expernment(EK4)with the auxiliary electrode on the cathode side achieved a removal efficiency of 58%,which is equivalent to the repair efficiency of EK2 but achieves a smaller energy consumption(115 kW·h/g).The results of the study on the treatment of chromium by PANI/NF composites show that the removal mechanism of Cr(?)in multi-electrode system is the synergistic effect of electromigration under the applied electric field and PANI adsorption.The PANI auxiliary electrode acts not only as an adsorbent,but also as an accelerator in the migration of Cr(?)to the anode,which means that it can intercept and adsorb some of the heavy metal ions passing through while strengthening the electrolysis process.In addition,the experimental data show that the acidic environment of the soil near the anode is more favorable to the adsorption process of the PANI auxiliary electrode.When the auxiliary electrode is placed in the cathode side,its operating energy consumption is the lowest. |
PDF Full Text Request