Study On The Effect Of Activated Carbon Fiber (ACF) Enhanced Electrokinetic For Remediation Of Cr(Ⅵ) In Soil

The problem of soil pollution in our country is increasingly serious,and the remediation of heavy metal-contaminated soil is imminent.In this study,Cr（Ⅵ）-contaminated soil was reconstructed using the technique of activated carbon fiber（ACF）-electrokinetic reconditioning,and the effects of anolyte p H,voltage,and electrode spacing on the electrokinetic repair process and repair efficiency were studied.In this study,a citric acid-sodium citrate buffer solution was used as the anolyte,and a cation exchange membrane was placed in the cathode chamber.The two combined to jointly control the pH of the soil system,the current and the electric conductivity of the cathodic and anodic electrolytes were analyzed over time.,Changes in soil moisture content,pH and conductivity before and after repair,change in total chromium content and morphology in the soil before and after the restoration,and the relationship between removal rate and energy consumption,and reached the following conclusions:（1）In the study of different pH of anode electrode solution for electrokinetic repair of Cr（Ⅵ）contaminated soil,the pH of each zone in the soil was basically controlled between 5.89-8.9.The lower the initial pH of the anolyte,the higher the moisture content in the soil after the restoration,and the lower the conductivity of the soil.With the increase of the standard distance from the anode,the content of chromium in the soil gradually decreased.When the p H of the anode electrode solution was 3,4 and 5,the corresponding maximum removal rates were:98.01%,90.11%,and 82.22%,respectively.The total removal rate of medium chromium was:73.18%,68.98%,57.69%,respectively.（2）In the study of different voltages for electrokinetic repair of Cr（Ⅵ）contaminated soil,the higher the voltage,the greater the current value,and the soil moisture content of the same soil area was also greater.The conductivity of the soil gradually decreases from the anode to the cathode.With increasing standard distance from the anode,the chromium content in the soil gradually decreases.When the applied voltage was 28 V,18 V,and 8 V,the corresponding maximum removal rates were:98.01%,98.01%,45.07%,respectively.The total removal rate of chromium in soil was:73.18%,67.60%,27.05%,respectively.（3）In the study of different electrode spacings for electrokinetic repair of Cr（Ⅵ）contaminated soil,the current change is faster when the distance was31.5 cm than when the current changes was 34.8 cm or 38.3cm.The smaller the electrode spacing,the higher the soil moisture content after repair.When the electrode spacing was 31.5 cm,34.8 cm and 38.3 cm,respectively,the corresponding maximum removal rate is above 98%.The total removal rate of chromium in soil was:73.18%,68.18%,63.15%,respectively.（4）The effect of three different factors on the removal efficiency of chromium in soil is as follows:electric field voltage>anode electrode solution pH>electrode spacing.（5）In the analysis of the relationship between chromium removal efficiency and energy consumption,the higher the removal efficiency of electric repair,the greater the energy consumption.The two are basically positively correlated;when the anolyte pH was 3,the voltage was 28 V,and the electrode spacing was 31.8 cm,the condition was determined as the best reaction condition,the total chromium removal rate was 73.18%in the soil,and the corresponding energy consumption was 4.25 kW·h·g^-1.（6）By analyzing the morphology of chromium in the soil before restoration and the form of chromium in the soil after the optimal reaction conditions,it can be known that the chromium content in the weak acid extractable state was the highest and the oxidizable chromium content was the highest in the simulated contaminated soil before electric restoration.The percentage of weak acid extractable chromium in each group of soil after electric repair was significantly reduced,and the chromium in the soil near the cathode was mainly in the form of residual chromium,indicating that the weak acid in the soil can extract chromium.Not only did the soil migrate out,but there was also a partial conversion to chromium in the form of a low-toxicity residue.