Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Solid
Patent
1995-03-14
1997-01-21
Phasge, Arun S.
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Solid
588204, C02F 1461
Patent
active
055956440
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for removing harmful substances, particularly in the earth's surface (hereinafter, "soil"); and an apparatus for carrying out this method.
BACKGROUND OF THE INVENTION
Ger. Pat. 3,920,342 discloses a method of decontaminating a contaminated soil region wherein a contaminant which is electrokinetically transportable and is contained in a soil region which contains an electrically conducting liquid is collected electrophoretically at at least one predetermined location of the soil region. For this purpose, a well is sunk in the soil region, wherewith the well tubing extends through the aquifer layer. An underpressure is applied to this well, whereby the soil gases contained in the soil, along with the harmful substance[s] therein, are removed by suction. In the middle of the well a lance-shaped central cathode is disposed which extends through the aquifer layer and the non-aquifer layer thereabove. At a small distance from the well, e.g. 6 m, a plurality of lance-chaped anodes are disposed. By applying a voltage between the anodes and the central cathode, an electric field directed radially toward the cathode is produced in the aquifer layer and the non-aquifer layer thereabove. The electric current produced in the aquifer layer, and the non-aquifer layer thereabove, by the applied voltage, causes ions of the harmful substance[s] to be produced by thermal ionization and to migrate toward the well. The known method is used exclusively in connection with electrokinetically transportable harmful substances.
The underlying problem of the present invention is to devise a method and apparatus for electrochemical removal of harmful substances, particularly in the earth's surface, whereby harmful substances can be removed, particularly in the earth's surface, in place (in situ), without local displacement or excavation.
SUMMARY OF THE INVENTION
The essential advantage consists of the fact that the invention enables one, for the first time, to break down harmful substances in situ in the earth's surface, without local displacement or excavation, even if such substances are not electrophoretically transportable, and even if ground water is not available as a transport medium (due to the soil not being saturated with water, i.e. in a non-aquifer region of the soil). Thus the invention makes it possible for the first time to remove nearly all organic substances and convert them essentially to the non-harmful substances carbon dioxide and water. The treatable substances include all organic compounds which can be decomposed by oxidation, even including nonpolar compounds, and including polar compounds which are first rendered nonpolar in the use of the inventive method (e.g. phenols, which are converted to benzenes after removal of the OH group). The invention is effective for organic harmful substances in solid, liquid, or gaseous form. Long-chain compounds, for example, are first broken down and are converted to progressively shorter-chain compounds, until the oxidation stage to produce carbon dioxide. E.g., by application of the method heptacosane (C.sub.27 H.sub.56) and triacontane (C.sub.30 H.sub.62) are degraded in a series of steps, to, e.g. , octane, propane, and butane, and eventually are oxidized to carbon dioxide. In the case of organic compounds with more complex structures, e.g. salicylic acid, first the substituent groups ("radicals") (OH and COOH groups) are removed and then the benzene nucleus is degraded by electrochemical action, to yield carbon dioxide and water. Polycyclic compounds, e.g. anthracene, are first cleaved to form individual benzene rings, and these are subjected to electrochemical oxidation. In contrast to electrophoresis, in these processes the harmful substances do not migrate in the soil. In other words, the decomposition and oxidation of the harmful substances occurs where said substances lie. Similar processes take place when the invention is applied to non-ionizable in organic materials. Thus, e.g., the molecular structur
REFERENCES:
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patent: 5256264 (1993-10-01), Hundenborn et al.
Land & Water-nu/Milieutechniek Nr. 5 (1988), (no month) "Elektro-reclamatie, een nieuwe techniek voor in-situ reiniging".
Doring Falk R.
Doring Niels
P + P Geotechnik GmbH
Phasge Arun S,.
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