Research On The Migration/transformation Mechanism Of POPs In Soil By EK Combined With Fe/C-PRB Technique

Persistent organic pollutants are toxic pollutants,which have potential threats to human health.In this paper,phenanthrene and 2,4-dichlorophenol are selected as target pollutants to construct electrodynamic and permeable reflection barrier technology(using iron-carbon mixture as Filling)joint remediation system,firstly studied the effect of initial pH and Fe/C mass ratio on the removal of pollutants in the micro-electrolysis reaction,and compared the adsorption of individual activated carbon with microelectrolysis technology;The effects of different voltages and repair time on the removal of phenanthrene and 2,4-DCP;finally,the interaction mechanism of EK and Fe/C-PRB in the combined system was studied,and phenanthrene and 2,were analyzed by GCMS.4-DCP degradation pathway.The main conclusions are as follows:(1)In aqueous solution,the research found that the initial pH and Fe/C ratio can significantly affect the removal efficiency of pollutants.The optimal conditions are as follows: When the initial pH is 5 and the Fe/C ratio is 1.5: 1,the removal effect on PHE is the best.When the initial pH is 3 and the Fe/C ratio is 1: 2,the removal effect of 2,4-DCP is the best.When comparing the micro-electrolysis and the removal effect of activated carbon adsorption,it was found that the micro-electrolysis was more significant in the removal of PHE.The activated carbon has a strong adsorption effect on 2,4-DCP,which can absorb 76% of 2,4-DCP in the solution.(2)When constructing a joint repair system of EK and Fe/C-PRB,it was found that the use of surfactants can promote electroosmotic flow,and it is more efficient to install PRB near the cathode.When the system was applied to soil organic pollution remediation,it was found that as the potential gradient increased from 1V/cm to 2V/cm,the migration effects of PHE and 2,4-DCP were significantly improved.After 10 days of repair,the total removal rates of PHE and 2,4-DCP reached 65.6% and 80.3%,respectively.(3)When studying the interaction mechanism between EK and Fe/C-PRB in the combined system,it was found that filling activated carbon or Fe/C mixture in PRB had no effect on the growth trend of cumulative electroosmotic flow,which indicates that the Fe/C micro-electrolysis reaction does not affect the electricity Seepage effect.Therefore,EK can coexist with Fe/C-PRB in the same system.Through SEM,XRD and XPS characterization,it was found that energization can accelerate the oxidation of iron and promote the efficiency of the micro-electrolytic reaction.(4)After the combined technique treatment,GC-MS was used to analyze the degradation pathways of PHE and 2,4-DCP in the soil.It was found that PHE was opened by a series of different pathways until a carbon chain was formed.Under acidification,2,4-DCP is dechlorinated and oxidized to p-benzoquinone until it is completely degraded.