Method for removing trichloroethylene from groundwater through electroreduction

Abstract

The invention relates to a method for removing trichloroethylene from groundwater through electroreduction. The method includes the following steps that firstly, a trichloro ethylene containing water body is introduced into a cathode chamber of a double-chamber double-electrode electrochemical removal device, and the pH of the cathode chamber is adjusted to be 5.8-6.4; the electrolyte of an anode chamber is a 8-10 g / L sodium sulfate solution; after powering on, the voltage is kept at 2.5 V for chemical treatment, and according to an existing government standard, the chemical treatment stop time is determined. Through molecular imprinting technical process, and the side, at a cation membrane, of a bipolar membrane has selective adsorption performance for TCE so as to improve the reduction efficiency of the TCE by electrodes. Elemental palladium is deposited on Ti-mesh, and the hydrochlorination performance of the TCE by the electrodes is improved. Pd@Ti-mesh is compounded on the side, at the anode membrane, of the bipolar membrane to achieve a zero polar distance between the electrodes and the membrane. H+ produced by hydrolysis can directly reach a cathode, the content of H+ on the electrode surfaces is improved, and the reduction speed of the TCE by the electrodes is promoted.

Description

technical field [0001] The invention relates to the technical field of removing trichlorethylene in groundwater, in particular to a method for removing trichlorethylene (TCE) in groundwater by electroreduction. Background technique [0002] Trichlorethylene (TCE) is a typical chlorinated organic compound (COCs), often used as a degreasing agent, cleaning agent, synthetic intermediate and cleaning agent, etc. . It has high permeability and persistence, and can gradually penetrate into groundwater from the surface, and is frequently detected in groundwater in my country and other countries. In addition, animal experiments and epidemiological investigations have shown that TCE has "three effects" and can strongly inhibit the central nervous system of the human body, which poses a great threat to the safety of underground drinking water and human health. It has been approved by many countries including China Included in the list of priority monitoring and control pollutants. ...

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Problems solved by technology

[0008] According to literature reports, since the 1980s to the present, titanium mesh electrodes loaded with metal oxides, nickel foam electrodes, and electroreduction systems with iron as the anode and copper foam and nickel foam as the cathode have been studied on the removal of TCE-containing groundwater. , achieved a good removal effect, but the residual TCE concentration in groundwater is difficult to meet the TCE content standard (70μg / L) in my country's underground drinking water, and there are problems such as low current efficiency and high energy consumption.

The main reasons are: 1) Trace TCE is difficult to enrich on the electrode surface: TCE mass transfer from water body to electrode is a key process of electroreduction, and low concentration substances have lower mass transfer rate. When it drops to 1mg / L, its mass transfer rate will also change from 1g / s·m 2 down to 0.05g / s m 2 , which makes it difficult for trace TCE to be enriched on the surface of the electrode, and thus cannot effectively remove TCE; 2) The electrode has no selective adsorption performance: the above-mentioned electrode has no selective adsorption performance for TCE, so that a large amount of coexisting substances (such as humic acid) are adsorbed to Electrode surface, direct consumption of electrons or H ads , resulting in decreased TCE removal rate and current efficiency

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