EP1027109B1 - Method for reductive dehalogenation of halogen-organic substances - Google Patents

Abstract

The invention relates to a method for reductive dehalogenation of halogen-organic substances which can be used in solid or liquid mixtures of substances. When the parameters of the inventive method are correspondingly adapted, liquids and halogen-organic contaminated soils can be mechanically treated and consequently reductively dehalogenated by applying mechanical energy and adding elementary alkali metal, earth-alkaline metal, aluminum or iron as a reducing agent and at least one reactant with slightly activated hydrogen as a hydrogen source.

Description

The invention relates to a method for reductive dehalogenation of halogenated organic substances in solid and liquid Mixtures of substances in which the substance or mixture of substances under Addition of elemental alkali metal, alkaline earth metal, aluminum or iron as a reducing agent and at least one Reagent with at least slightly activated hydrogen as a hydrogen source is treated. It is particularly useful for detoxification of organically contaminated soils and others complex materials, but also for decontamination and optionally recycling liquid or predominantly liquid halogen organically contaminated substances.

Toxic polyhalogenated organic pollutants can be So far under economically and ecologically equally advantageous and forward-looking terms with none of the nowadays known detoxification technologies. Frequently are these substances as impurities, also in large quantities, in soils, river or marine sediments, sewage sludge, filter dust, Building materials, seepage oils, waste oils etc. before, i.e. associated with an indefinable number of foreign and Accompanying substances with different properties. The detoxification and remediation of such complex, heterogeneous, solid, solid-liquid or liquid materials and contaminated sites poses particularly extensive problems.

There are a number of thermal and other high energy ones Process for the destruction of dangerous hydrocarbons of the type mentioned above, even for those that are special in complex built materials are distributed. This includes u. a. the high temperature combustion and the combustion in Glass or salt baths. However, each of these methods points some specific disadvantages, so that development needs for alternative technologies exist.

For example, high temperature combustion is not just extreme costly, but also poses new problems. With polychlorinated compounds it leads to the formation of PCDD / PCDF, which are in complex downstream process steps removed from the flue gas and filter dust and eventually need to be disposed of. The current type of There is often "disposal" of these highly toxic dusts in a deposit on so-called hazardous waste landfills.

Biological methods to break down toxic organic compounds in complex matrices also have method-specific ones Disadvantages that limit their general applicability.

Processes based on alkali metals have a certain spread found in which finely divided metal suspensions or -Dispersions in indifferent liquid media, such as. B. White oil, are used; however, they are in their applicability mostly limited to a few special problems, i.e. the detoxification of relatively pure, liquid pollutants or mixtures of pollutants or practically homogeneous, contaminated, water-free liquids, such as B. PCB-containing transformers or used engine oils.

Other processes in which other base metals with low reducing power are used alone, such as. B. aluminum, zinc, or iron are not for detoxification of important special groups of substances, for. B. polychlorinated aromatics, suitable because the latter can not be fully dechlorinated with these metals. Not all chlorine atoms of a polychlorinated molecule are removed in this way, and detoxification is not achieved or only in the presence of toxic catalysts or promoters, for example triphenylphosphine, nickel or nickel compounds, which also causes major problems for toxicological reasons. The use of toxic substances for dehalogenation of organohalogen in soils, sediments etc.
means only the replacement of existing contamination by another and does not offer a solution to the problem.

The processes known for liquids or liquid mixtures cannot be easily transferred to solids. In Halogenated organics contained in solids can be due to the high Transport inhibitions common in solid-solid reactions difficult to be reached by reagents. In particular can be polyhalogenated organic matter in the environment as impurities z. B. in soils, river or marine sediments, Sewage sludge, filter dust, building materials or Seepage oils, therefore solid or liquid, without exception very much heterogeneous materials can be found in large quantities, due to the complex state forms of these matrices and the resulting diverse transport inhibitions in particular difficult to attack and therefore only incomplete or not at all Bring reaction.

The problem underlying the invention is therefore a process for the reductive dehalogenation of organic halogen Design fabrics so that it is possible to create different ones heterogeneous solid and liquid mixtures, in particular also complex mixtures and contaminated soils with partially unknown other ingredients in one to dehalogenate universal processes as far as possible, whereby no new harmful by-products should arise.

The method should be as easy to use as possible Own process flow and work relatively quickly.

To solve this problem is according to the invention in one Process of the type mentioned provided that the halogen organic Substance or the mixture of substances in one all Grinding material with mechanical activation in reductively practically completely dehalogenated in one step becomes.

The invention is applicable to organohalogen compounds which in solid or liquid foreign substances or foreign substance mixtures are included, but also as solid or liquid pure substances or can be present in mixtures of these. These substances or mixtures of substances, as far as the basic process is concerned, in dealt with in a single process step, i.e. it will all components including mild reaction conditions at least one reducing agent and one hydrogen source, intimate mixed.

The process includes grinding the reactants under Entry of a more or less large amount of mechanical Energy. As a result, at least a fine distribution in very small particles and therefore an intensive mixing of all Components of the mixture causes so that between the used reagents and the organohalogen in time Intensive contact is established and this means be brought to the desired reaction. In addition, the reactivity of the solid components through the fine distribution increased due to surface physical effects.

In addition, the reactivity becomes with sufficient energy input greatly increased. The mechanically activated treatment in solid or solid-liquid phase seems particularly suitable for ' the complete or almost complete degradation of polyhalogenated Compounds using hydrogen donors.

By increasing the reactivity of solids as a result special mechanical activation, can also substances in complex solid or solid-liquid materials are distributed, are attacked chemically and implemented efficiently. consequently organic pollutants can also be found in solid matrices such as soils, sediments, etc., by means of mechanical Activation of targeted degradation reactions.

Compared to high temperature combustion and other high energy The method according to the invention has the Advantage that under mild reaction conditions, i.e. in general at room temperature and under normal pressure, feasible and is technically far less complex. It is therefore also can be designed for small mobile systems. Another advantage is there in the fact that there may be recycling or reuse of the materials to be decontaminated is possible with a Combustion would be destroyed in principle.

The process basically works at low temperatures, preferably at room temperature under normal pressure. there it is possible, however, that due to the intensive mechanical input Energy and / or that released during dehalogenation Heat of reaction in the course of the process a warming entry.

The metallic reducing agent is advantageously at least in little excess used. The required amount of reducing agent can be carried out in preliminary tests on samples of the specific decontamination object be determined.

Common metals are reducing agents, namely in particular alkali metals, alkaline earth metals, aluminum and Iron provided. Among the alkali metals are sodium and potassium preferred, among the alkaline earths magnesium and calcium. However, using the principles of this invention other base metals can also be used, taking into account is that the formation of toxic products should be avoided.

Reductive removal of halogens from organic halogen Fabrics using base metals, in particular In principle, alkali metals have long been known and mechanistic well examined. To date, however, has been insufficient It has been recognized that some of these reactions can also be used for elimination of toxic organic matter in our environment let use. According to the invention, the reduction with Metal 'by the addition of mechanical energy and Supported addition of at least one hydrogen donor.

It is surprising that polychlorinated aromatics in liquid, solid or solid-liquid substances also with magnesium in one One-pot reaction can be completely dechlorinated at room temperature are. Et al Magnesium chips were used, which in the Laboratory as well as in industry for decades on a large scale Scope used to generate Grignard reagents. Contrary to popular belief that Grignard reactions practically only in special, highly cleaned, toxicologically questionable and highly flammable solvents, such as As diethyl ether or tetrahydrofuran, to this under strict Exclusion of moisture, with protective gas and under use special catalysts are feasible, for example, that in a purely liquid phase by itself Dissolution of the metal in methanol, in a solid matrix Application of ball milling with the slight addition of methanol, Performing ethanol or low molecular weight primary amines of coupled Grignard and Zerewitinoff reactions succeeded in a solid sand matrix.

As a hydrogen source with at least slightly activated hydrogen are preferably alcohols, ethers, polyethers, amines or hydroxides, such as. As calcium hydroxide, or metal or Non-metal hydrides such as Calcium hydride, sodium hydride, sodium boranate, Lithium alanate, trialkylsilanes, polyalkylhydrogensiloxanes, used individually or in combination.

From the group of alcohols, for example, low molecular weight aliphatic alcohols can be used. Under Low molecular weight alcohols are, for example, aliphatic To understand alcohols with 1 to 7 carbon atoms such as methanol, Ethanol, propanol, isopropanol, butanol, sec- and tert-butanol, Pentanol, hexanol, heptanol, cyclopropanol, cyclobutanol, Cyclopentanol, cyclohexanol, cycloheptanol, 2-methylcyclopropanol, Cyclopropylmethanol, polyalkylene glycols, simply etherified polyalkylene glycols, amino alcohols, polyols, such as. Ethylene glycol, glycerin, pentaerythritol, etc.

Simple symmetrical groups, for example, can be selected from the ether group or asymmetric aliphatic ethers, cyclic ethers or polyether can be used. Examples include diethyl ether, Propyl ether, isopropyl ether, n-butyl ether and dimers or trimeric polyethers, coronands, cryptands, spherands, Ether amines, e.g. 2-methoxyethylamine etc.

From the group of amines are aliphatic amines and below lower primary or secondary aliphatic amines are preferred. Examples of suitable amines are: primary, secondary or tertiary aliphatic and alicyclic mono- or polyamines, Methylamine, ethylamine, 1- and 2-propylamine, 1- and 2-butylamine, Ethylenediamine, tri-, tetra-, penta-, hexamethylenediamine, dimethylamine, Diethylamine, di-n-propylamine, cyclopentylamine and cyclohexylamine, Nitrogen heterocycles and perhydro nitrogen heterocycles, e.g. Piperidine, 1- (2-aminoethyl) piperazine, 1- (2-aminoethyl) pyrrolidine and 1- (2-aminoethyl) piperidine, 4- (2-aminoethyl) morpholine. It is also suitable for the same purpose liquid ammonia.

As an alternative to the amines, certain amides can also be considered. For example: 1,3 dimethyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidone can be used (Dimethylpropylene, DMPU), 1,3-dimethyl-2-imidazolidinone (N, N-dimethylethylene urea, DMEU), 1-methyl-2-pyrrolidone (NMP), 1-ethyl-2-pyrrolidone, N, N-diethylacetamide, N, N-diethylpropionamide, N, N-diethylisobutyramide.

There is no need to add a hydrogen source separately if it is known that the subject to be treated Mixture already a substance suitable as a hydrogen source is in sufficient quantity.

The mechanical preparation according to the invention can be carried out in one Ground in a mechanical mill, for example a ball mill, hammer mill or vibrating mill. Additional grinding aids can be used for this grinding become. Substances are generally used as grinding aids the surface energy and / or the plastic deformation of Can reduce solids when exposed to mechanical energy. These include, for example: Surface-active substances in various forms of condition or preparation, e.g. quaternary ammonium compounds that are not only in pure substance can be used, but also immobilized on inert, surface-active carriers, such as layered silicates, clays (so-called "organophilic bentonites") also substituted alkylimidazolines and sulfosuccinamides, fatty acids, fatty acid esters and - amides, primary, secondary and tertiary alkyl and fatty amines with one or more amine groups, alicyclic amines, such as, for example Cyclohexylamine, polyhydrogen nitrogen heterocycles, such as. Piperidine (hexahydropyridine) mono-, di- or trialkanolamines, simple glycols, polyalkylene glycols, e.g. polyethylene and polypropylene glycols, and their mono- or diether, Organosilicon compounds, especially silicones, special for inorganic salts suitable for the purpose, e.g. Aluminum chloride.

The mechanically activated reaction process can be carried out by the additional use of reaction accelerators be reinforced or accelerated. As a reaction accelerator can be used fabrics that are able to base Metals, especially alkali and alkaline earth metals, partially or completely dissolve and / or dissociate them in metal cations and anions and / or the formation of solvated To transport electrons and / or organometallic compounds, such as. alkali or alkaline earth metal organic compounds, to solvate and / or stabilize, e.g. liquid Ammonia, primary, secondary or tertiary aliphatic and alicyclic mono- or polyamines, polyhydrogen nitrogen heterocycles, aliphatic and cyclic monoethers, podands, coronands, Cryptands, spherands, ether amines, e.g. 2-methoxyethylamine, Amides such as -pyrimidone, 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) (Dimethyl propylene urea, DMPU), 1,3-dimethyl-2-imidazolidinone (N, N-dimethylethylene urea, DMEU), 1-methyl-2-pyrrolidone (NMP), 1-ethyl-2-pyrrolidone, N, N-diethylacetamide, N, N-diethylpropionamide, N / N-diethylisobutyramide.

The grinding aid (s) and / or reaction accelerator can Substance or mixture of substances in a subsequent step, i.e. separately after adding the reactants, added and mechanically be incorporated.

The metallic reducing agent can on the one hand be mixed can be added directly in pure form. This is particularly useful alkaline earth metals, less in the air are more reactive than the alkali metals, e.g. with magnesium chips.

Alternatively, the metallic reducing agent can be in a preparation are dispersed or suspended, for example dispersed in a non-oxidizing liquid or the liquid hydrogen source. Dispersions are advantageous to use from the selected metal in white oil, paraffin or in Ethers, including polyethers such as diglyme, triglyme, tetraglyme, polyethylene glycol and polyethylene glycol derivatives, etherified diund Polyglymen.

Furthermore, the metallic reducing agent can be mixed with a solid Carrier mixed or applied to this. As advantageous preparation has e.g. a mixture of alkali metal, especially sodium, with calcium silicate or Calcium oxide proven.

It has been found that ball milling is also used to increase reactivity of the metals alone in an isolated step suitable by mechanical fine distribution, in particular for the fine distribution of alkali metals on surface-active solid inert carriers. Compared to conventional procedures, in which in a special apparatus with stirring high temperature molten alkali metal on solid inert carriers applied, the new method offers the advantage that you work at room temperature and the procedure is easier and faster by using the alkali metal and the carrier material simply together in a grinding vessel or the mill fills and within a few minutes to a homogeneous, finely powdered dispersion.

The method can thus also be designed in two stages , e.g. by ball milling in a first step pre-produced finely divided metal only in a second Step with the addition of reaction accelerators and if necessary other additives are ground. It is also possible also alkali metal dispersions obtained by conventional means, i.e. both dispersions in inert fluids as well on inert solid supports, with reaction accelerators and If necessary, other additives in an organohalogenous Solid grinding or mixing and thereby dehalogenation to effect.

The method can also be used to complement other methods, e.g. of washing processes, used or combined with these become. A previous treatment of contaminated soils with Calcium oxide (quicklime or quicklime), which is also found in others Preparation process is known and among other things to dry the Mixture can be useful in some cases.

The process can be carried out batchwise, batchwise or continuously be performed.

In the discontinuous mode of operation, first of all Reaction partner, i.e. at least the substance to be treated or the mixture / mixture, the metallic reducing agent and the Hydrogen donor, placed in a device that is mechanical Machining enables, like a mill or a (dynamic) Mixer. When decontaminating in solid or solid-liquid Media becomes more of a mill, e.g. a ball mill, a hammer mill or a vibratory mill can be used while at a mixer can be sufficient for liquid systems. As a mixer For example, friction, screw or roller mixers are suitable.

It is an advantage of the invention that the machining in only one step can take place, the reactants being sequential or can be added gradually. A continuous one Procedures could, for example, in a Screw mill or a screw mixer.

In the following, the process is illustrated using a few examples explained.

example 1 Chlophen-contaminated model floor / Na-Ca silicate / n-butylamine

In an eccentric vibratory mill "ESM 234", from Siebtechnik, Mülheim a. d. Ruhr, 80% with steel balls (diameter 20 each mm) is filled, 3.8 kg quartz sand (bulk density 1.27 g / ml) with 180 g calcium oxide for drying for ten minutes mixed by grinding. You mix, also by grinding, 10.2 g of n-butylamine for one minute. Last will be 156.7 g of a 26% sodium calcium silicate dispersion were added and ground for 30 minutes with the contaminated model floor.

The model floor was artificial by adding a mixture of 5 g of Chlophen A30 and 150 g of calcium oxide / calcium hydroxide, the five Minutes, were contaminated.

GC-ECD analysis (internal standard: decachlorobiphenyl) of one Model soil sample after this treatment shows that the PCB by 99.7%. Furthermore, the presence may be due to the GC findings or formation of other halogenated substances excluded become.

Production of the 25% sodium calcium silicate dispersion : 150 g of surface-active calcium silicate (in a centrifugal ball mill S1, Retsch, Haan, 500 ml stainless steel grinding bowl with 3 stainless steel balls (diameter 20 mm each) and stainless steel sealing cap with rubber sealing ring. e.g. "Cape-Boards Siborit" GmbH, Lüneburg, or Xonolit, "Eternit" SA, Kapelle Op den Bor, Belgium), mixed with 50 g sodium pieces and covered with argon for 5 to 15 minutes at high speed (≈ 500min ^-1 ) grind. A dark gray, homogeneous, highly reactive powder is obtained. Anhydrous clays, for example Tixogel or Tixosorb from Südchemie, Moosburg, have proven to be particularly favorable carrier materials.

Example 2 Chlophen-contaminated model soil / Mg / tetraglyme / n-butylamine

In an eccentric vibratory mill "ESM 234" (data see example 1) 3.8 kg quartz sand (bulk density 1.27 g / ml) with 200g calcium oxide mixed by grinding for drying for ten minutes. A mixture is mixed, likewise by grinding from 5 g of Chlophen A30 and 150 g of calcium oxide / calcium hydroxide, 18.2 g n-butylamine and 51.1 g tetraethylene glycol dimethyl ether (Tetraglyme) for two minutes. Finally, 102 g of magnesium shavings ground in for two hours.

The GC-ECD analysis (internal standard: decachlorobiphenyl) confirms a 99.7% reduction in PCB. The presence or education other halogenated substances can be excluded.

Example 3

Pretreated PCB contaminated soil / Na / n-propylamine Treated is a PCB-contaminated, cohesive soil that previously was subjected to a washing process with water and surfactants. From the suspended fraction of this process, which is carried out with the help of Flocculants based on polyamide was precipitated do not remove residual contamination of approx. 250 ppm PCB. In an eccentric vibratory mill "ESM 234" (for data see Example 1). 3 kg of this PCB-contaminated soil fraction, residual moisture after thermal predrying approx. 2%, with 200 g calcium oxide mixed by grinding for drying for 30 minutes. you mixes, likewise by grinding, 150 g of n-propylamine Minute and waits 5 minutes. Finally, 200 g Sodium in the form of cylindrical pieces (each 1 to 2 cm long and thick) ground in for 45 minutes.

The GC-ECD analysis (internal standard: decachlorobiphenyl) confirms a 98.5% reduction in PCB. The presence or education other halogenated substances can be excluded.

Due to the high polyamide admixtures, one had to be clear higher sodium portion than are used for the complete dechlorination of the PCB alone was required would.

Example 4

Pretreated PCB contaminated soil / Na / tetraglyme In an eccentric vibratory mill "ESM 234" (data see example 1) 3 kg of the PCB-contaminated soil fraction used in Example 4 from a washing process, residual moisture after thermal Predrying approx. 2%, with 200 g calcium oxide for drying mixed by grinding for 30 minutes. You mix likewise by grinding, 100 g of tetraglyme for one minute on. Finally, 200 g of sodium (cylindrical pieces, 1 to 2 cm long and thick) ground in for 90 minutes and allowed to then the contents of the mill overnight without further action stand.

The GC-ECD analysis (internal standard: decachlorobiphenyl) confirms 92% degradation of the PCB after 90 minutes after standing over 99.9% overnight. The presence or The formation of other halogenated substances can be excluded.

Example 5 Chlophen-contaminated sea sand / Na-CaO / ECOH triglyme

0.05 g Chophen A30 are mixed with 10 g sea sand pA, 0.25 g triglyme and 0.52 g ethanol (= 19.1 equivalents per total chlorine) in a centrifugal ball mill S1, from Retsch, Haan, 50 ml stainless steel grinding bowl with 3 stainless steel balls (diameter 10 mm each) and stainless steel sealing cap with rubber sealing ring, grind for one minute at maximum speed (≈500 min ^-1 ). After 1 minute of grinding, the grinding vessel is removed from the mill, opened and rinsed with argon (5.0, Linde) under an inverted funnel. Then sodium calcium oxide dispersion (52% Na) is quickly added under an argon shower, briefly gassed with argon and finally the grinding bowl lid is replaced. The grinding time is one hour at the highest speed.

The GC-MS analysis shows that the PCB has been completely degraded (Main degradation product phenylcyclohexane). The presence or education other halogenated substances can be excluded.

Preparation of a 52% Sodium Calcium Oxide Dispersion : One way to dryly distribute sodium onto calcium oxide is to grind small pieces of sodium with calcium oxide in a centrifugal ball mill for 5 to 15 minutes, as described for surface-active materials (see above). In this way, 5% of the alkali metal can be homogeneously distributed on the support. Useful sodium-calcium oxide dispersions are obtained if the alkali metal is first allowed to act on calcium oxide in the presence of toluene under reflux conditions and then the mixture is mixed at high speed with a high-speed stirrer or dispersant, for example Ultra-Turrax from "Janke &Kunkel" mixed. After the toluene has been distilled off, a dark gray, finely powdered solid which remains completely homogeneous on visual inspection remains. According to this procedure, different concentrations of the alkali metal in the dispersion can be realized practically continuously. In addition to the sodium calcium oxide system, the method can be used very flexibly: for example, it can also be used to prepare a 25% potassium calcium oxide dispersion that looks like the sodium dispersion. A dark gray, completely homogeneous powder is obtained. However, it is pyrophoric in air and therefore cannot be used for the dechlorination of polychloroaromatics in solid or solid-liquid matrices. Such a potassium-calcium oxide dispersion would, however, have interesting applications for organic-chemical implementations on the laboratory scale with suitable protective gas and security technology.

Example 6 Chlophen, contaminated sea sand (model) / Mg / MeOH

In a centrifugal ball mill S 1 (see Example 5), 15 g of sea sand (pA), 0.5 g of calcium oxide-calcium hydroxide mixture, produced by partially quenching 56 g of CaO with 14 g of H ₂ O, 0.5 g of triglyme 0.11 g of Chlophen A30, 0.3544 g of methanol and 0.51 g of magnesium powder, after the mixture has been covered with argon in an open grinding bowl, milled for 5 hours at high speed.

The GC-MS analysis shows that the PCB has been completely degraded (Main breakdown product: biphenyl, little phenylcyclohexane in addition). The presence or formation of other halogenated substances can be excluded.

Example 7 Chlophen-contaminated sea sand (model) / Mg / n-propylamine

In a centrifugal ball mill S 1 (see example 5), 15 g of sea sand (p.A.), 1 g calcium oxide-calcium hydroxide mixture, 0.25 ml n-propylamine, 0.1 g Chlophen A30, and 0.76 g magnesium shavings grind for 1 hour at maximum speed.

The GC analysis shows that the PCB has been completely degraded (Main breakdown product: biphenyl, alongside 1-phenylcyclohexene, little Phenylcyclohexan). The presence or formation of other halogenated Substances can be excluded.

Example 8 Dehalogenation of polychloroaromatics in solution with addition of small amounts of low-chain aliphatic amines.

It is surprisingly found that polychloroaromatics such as 1,3,5-TCB can be dechlorinated much better with sodium in the presence of even small amounts of n-butylamine than in other systems investigated. Dechlorination of 1,3,5-trichlorobenzene in dodecylbenzene (3 ml each) ^a) by the action of approx. 2 equivalents each sodium with the addition of various polyethers (5 ml each) at room temperature after 2 hours. Na eq. 1.99 2:05 2.11 2.02 2.05 additions - diglyme triglyme PEGDM 500 TEGM n _rel (Cl ^- ) [Mol%] 3.7 59.0 58.9 69.6 44.1 Dechlorination of 1,3,5-trichlorobenzene in dodecylbenzene (3 ml each) with ≈2 equivalents each sodium in the presence of various aliphatic amines under changing conditions after 2 hours at room temperature. Na eq. 2:03 2:07 1.97 Amin Et ₃ N Et ₂ NH n-BuNH ₂ Amine Volume [ml] / eq. 2 / 3.5 2 / 4.6 1 / 2.4 n _rel (CL ^- ) [mol%] 2.3 31.4 94.2 Dechlorination of 1,3,5-trichlorobenzene in dodecylbenzene (3 ml each) with ≈2 eq. Sodium in n-butylamine-diglyme mixtures, reduction of the amine content after 2 hours at room temperature. Na eq. 2:04 2:04 2:01 2:02 n-BuNH ₂ [ml] / eq. 2 / 4.88 0.4 / 0.98 0.2 / 0.49 0.05 / 0.12 Diglyme [ml] 0.5 4 4 4 n _rel (Cl ^- ) [mol%] 95.5 91.7 91.3 91.4

The mechanical processing can be done by stirring in a reactor or done in a suitable mixer.

Example 9 Clophen-contaminated sea sand (model) / Mg / DMPU

In a centrifugal ball mill S 1 (see Example 5) 7.5 g of sea sand (p.A.) and 2.0 g of magnesium shavings under argon for five minutes ground. Then add 0.1 g of Chlophen A30. 7.5 g sea sand (p.A.) and 0.5 g of 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) pyrimidone (Dimethylpropylene urea, DMPU) added, rinses with Argon and ground at maximum speed for 30 minutes. The GC analysis shows a complete degradation of the PCB (Main breakdown product: biphenyl). The experiment can be done with others special amides instead of DMPU, e.g. 1,3-dimethyl-2-imidazolidinone (N-N-dimethylethylene urea, DMEU) or 1-methyl-2-pyrrolidone (NMP), in a very similar form with perform the same result.

Example 10 Dehalogenation in pure liquids

In a centrifugal ball mill S 1 (see Example 6), 7.0 g of decane, in which 0.8 g of Chlophen A 30 were dissolved and still Contain 2g n-propylamine, with 9.4g magnesium shavings at the highest Grind speed for 30 minutes.

The GC-FID analysis then shows an almost complete breakdown the PCB (degradation product: biphenyl, next to it only subordinate three mono- or dichlorobiphenyls).

Untreated and treated according to the inventive method Samples were examined by gas chromatography. pictures 1 through 6 show the results of some exemplary gas chromatographic analyzes before and after treatment. The analyzes show that it is possible to do even complex ones Treat mixtures effectively in a short time (see Fig. 3 until 6)

With the help of the method according to the invention, it is possible to use polychlorinated organic pollutants, even with an abundance of foreign substances and accompanying substances in complex solid or solid-liquid Materials are available and even distributed can be strongly adsorptively bound, selectively by complete reductive dechlorination at room temperature within Minutes completely. Of course, Pollutants that are found in relatively pure form, such as e.g. highly concentrated PCB oils or insecticidal HCH isomers, e.g. in the order of several 10,000 tons were deposited in open pits in the Bitterfeld area (Purity up to 95%), particularly effective detoxification.

In the case of transformer oils, the process according to the invention offers itself as an alternative to existing processes (Degussa sodium, NaPEG, KPEG, KPEG-PLUS), since it has a simpler and safer design and can be implemented with simple means under mild conditions. This offers the possibility of recycling contaminated oils to a large extent instead of having to burn them. Especially have transformer oils
a high material and thus reuse value, which would, however, be completely written off if incinerated.

The organic pollutants can be classified under ecological and economically favorable conditions at room temperature and in a short time Time, especially when it is in different Mixtures occur, completely eliminate them.

The pollutants are directly in the matrix in which they are distributed are degraded by simply structured reagents. For example, these can be materials that elsewhere in large quantities as residues, and thereby lead to a meaningful utilization to let.

There are only a few, non- or less toxic and biological degradable products formed. The special environmental compatibility results from the complete implementation of the reducing agent with all organically bound halogen to a harmless, inorganic halide. At the same time, the halogen-free base body of the polyhalogenated compounds.

Detoxified materials such as Building materials or waste oils can be fed into useful recycling measures or recycled become.

For cumbersome and costly post-treatments, such as removing and eliminating excess reagents or toxic breakdown products can usually be dispensed with.

The new process consequently eliminates the disadvantages of today practiced on a larger scale during the remediation of contaminated sites Processes such as high temperature combustion avoided.

Halogenorganisch belastete Böden und Sedimente;

PCB-kontaminierte Baumaterialien und Gebäudeeinrichtungen (Wandanstriche, Feinputz, elastische Dehn- und Fensterfugenmassen in Gebäuden unterschiedlicher Art);

PCB-belastete Klärschlämme;

Detoxifizierung von halogenorganisch kontaminierten Filterstäuben, beispielsweise aus der Stahlindustrie oder Müllverbrennungsanlagen;

Entsorgung von Produktionsrückständen aus der chemischen Industrie, etwa aus der Lindanherstellung (HCH-Isomere in der Größenordnung von mehreren 10.000 t im Raum Bitterfeld);

Dioxin-haltiger Rotschlamm;

Dekontaminierung von PCB-belasteten Transformatoren- und Motorölen;

Dekontaminierung von halogenorganisch kontaminierten Filtermaterialien, z.B. Adsorbentien zur Reinigung von Abgasen, Abwasserströmen, wie etwa Aktivkohle, Tone etc.

Areas of application for the method according to the invention are in particular:

Halogen-organic soils and sediments;

PCB-contaminated building materials and building equipment (wall coatings, fine plaster, elastic expansion and window joint compounds in buildings of different types);

PCB-contaminated sewage sludge;

Detoxification of organically contaminated filter dusts, for example from the steel industry or waste incineration plants;

Disposal of production residues from the chemical industry, for example from lindane production (HCH isomers in the order of magnitude of several 10,000 t in the Bitterfeld area);

Red mud containing dioxins;

Decontamination of PCB-contaminated transformer and motor oils;

Decontamination of organically contaminated filter materials, e.g. adsorbents for cleaning exhaust gases, waste water streams, such as activated carbon, clays, etc.

Claims (12)

1. Process for the reductive dehydrogenation of organohalogen compounds in solid and liquid mixtures, in which the compound or the mixture is treated with addition of elemental alkali metal, alkaline earth metal, aluminium or iron as reducing agent and at least one reagent containing at least slightly activated hydrogen as hydrogen source, characterized in that the organohalogen compound or the mixture is reductively dehalogenated virtually completely with mechanical activation in one step in a grinding comprising all materials.
2. Process according to Claim 1, characterized in that the reducing agent is preferably Na, K, Mg, Ca or Al.
3. Process according to Claim 1 or 2, characterized in that the hydrogen source is alcohols, ethers, polyethers, amines, hydroxides or hydrides, individually or in combination.
4. Process according to Claim 3, characterized in that the amine is at least one aliphatic amine, preferably primary or secondary aliphatic amine.
5. Process according to one of Claims 1 to 4, characterized in that grinding aids and/or reaction accelerators are additionally used.
6. Process according to Claim 5, characterized in that the grinding aids are substances which can reduce or prevent possible plastic deformation and/or agglomeration of solids under the action of mechanical energy, for example certain surface-active substances.
7. Process according to Claim 5, characterized in that reaction accelerators are used which at least partially dissolve base metals and/or promote their dissociation into metal cations and metal anions and/or promote the formation of solvated electrons and/or solvate and/or stabilize organometallic compounds.
8. Process according to one of Claims 5 to 7, characterized in that the grinding aid(s) and/or reaction accelerator(s) are added to the compound or mixture in an upstream or downstream step and are mechanically incorporated or ground.
9. Process according to one of Claims 1 to 8, characterized in that the metallic reducing agent is present in a preparation, for example dispersed in a non-oxidizing liquid or the liquid-hydrogen source or an inert solid support.
10. Process according to Claim 9, characterized in that the reducing agent is present in the form of a paraffin suspension, an ether dispersion or a polyether dispersion.
11. Process according to one of Claims 1 to 10, characterized in that the mixture is treated and/or dried in an upstream process step with calcium oxide and/or other additives.
12. Process according to one of Claims 1 to 11, characterized in that the mechanical treatment is performed in a mill, for example a ball mill, a hammer mill or a vibratory mill, or in a mixer which adequately transmits mechanical energy, preferably a dynamic mixer, for example a friction mixer, screw mixer or roller mixer.

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