A New Technology Of Electrokinetic Remediation And The Research On Removal Cu In Red Soils

Soil contaminated by heavy metals is one of the environmental problems that should be resolved urgently. Soil pollution is accumulative, lagging, dormant, and irreversible, therefore, soil pollution is usually difficult to be remedied and treated. Based on the researches of at home and abroad and combined actual conditions, this paper mainly studied the technic of electrokinetic remediation.Electrokinetic remediation technique is an advancing task of global environment science and technology. Its principle is that: electrodes are installed vertically or horizontally in a contaminated soil and a low direct urrent voltage gradient or current is applied across the electrodes, results in oxidation at the anode, generating an acid front that cause desorption and dissolution of heavy metals. The desorped and dissoluted heavy metals are migrated toward cathode reservoir by electric field and ions concentration grads by the means of electromigration, electroosmosis and diffusing.Based conventional electrokinetic remediation, combined some soil remediation technics such as: soil leaching and soil liquid extraction, a new electrokinetic remediation technology for removing heavy metal from soil was invented. And it was studied that the new technology was applied to remove Cu in unsaturated soil. The results show that the new technology was applicable to romoving Cu from the Cu contaminated red soil; there would be electroosmosis in unsaturated soil when a low level direct electric current is applied across it, electroosmotic solution containing heavy metal ions, heavy metal ions would be removed with the electroosmosis solution flowing out from soil; compared with the conventional electrokinetic remediation, the change of the soil near the electrodes weakened, concentration of Cu in cathode region is lower after experiment, as the leaching liquor was constantly drawn out, that is to say, the solution of soil was constantly updated; the soil temperature increment proportional to the current density in the incipient stage of this experiment, but in the metaphase and anaphase, the soil temperature kept at a relatively low level insteat of rise gradually; in the incipient stage of this experiment, the homogenization of soil moisture is more different with the greater of the current strength, but in the metaphase and anaphase, the soil moisture had no significant change; after the initial increasing, the cell voltage tended to stabilization in the metaphase and anaphase. It should choose a lower level of current when using the new technology, for removal efficiency of copper is not strictly proportional with the current intensity; in the meantime, the pH of the leaching liquor should be at about 3.5, heavy metal would infiltrate into underlayer soil if the pH is too low, the soil near the cathode would not always be acidic if pH is too high, as a result it would affect removal efficiency; the soil temperature decreased in the metaphase and anaphase compared to the incipient stage, therefore, it could avoide the soil temperature going up too high when applying the new technology into remedying the red soil contaminated with Cu; it could shorten the experimental period and improve the remediation efficiency when we use the new electrokinetic remediation technology for remedying the contaminated soil.