METHOD FOR THE DEMOLITION AND THE REMOVAL OF HALOGENATED AND AROMATIC HYDROCARBONS FROM MATERIALS THAT CONTAIN THEM

Abstract: Method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that contain them, characterised in that the material to be treated is made to react - in an acid and/or alkaline environment, or vice versa - with a reagent selected from the group comprising zinc, iron, iron disulphide, ferrous sulphide, ferrous sulphate and mixtures thereof.

Description: Method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that contain them. The present invention relates to the field of the processing of wastes, both of aqueous and of solid matrix, contaminated by halogenated and aromatic hydrocarbons. As it is known, according to current laws such wastes must be destroyed by thermal way or, alternatively, may be incorporated in semisolid materials and dumped in specially provided dangerous waste dumps. The latter technique, whose safety however, from the point of view of the guarantee of stability over time, has not been proved once and for all, presents the drawback of utilising dumps, in case usable for more suitable materials, and to postpone the natural transformation, essential to avoid negative effects on our planet. On the contrary, thermal destruction technique constitutes the most widely encouraged solution for a radical and final elimination of the disposal problem. However, given the delicacy of the treatment (formation of demolition intermediates and/or of highly toxic substances) this technique requires a particular care, thereby making essential the resorting to sophisticated plants with very high costs. Therefore, in this specific field the demand exists for the availability of a simple and low-cost method capable of transforming halogenated and aromatic hydrocarbons present in wastes into atoxic materials, without thereby causing negative environmental impacts. The present invention allows to meet this demand thoroughly, further showing other advantages that shall be evident hereinafter. Therefore, the subject of the present invention is a method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that contain them, characterised in that the materials to be treated is made to react - in an acid and/or alkaline environment, or viceversa - with a reagent selected from the group comprising zinc, iron, iron disulphide, ferrous sulphide, ferrous sulphate and mixtures thereof. Treatment in acid invironment is preferably carried out at a pH lesser than 6. The acid environment may be obtained with the addition of a mineral acid, preferably selected from the group comprising sulphuric acid, hydrochloride acid and combinations thereof. Treatment in alkaline environment is preferably carried out at a pH greater than 8. The alkaline environment may be obtained with the addition of an alkaline or an alkaline earth base, preferably selected from the group comprising sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) 2 ) and combinations thereof. The duration of the acid environment treatment is greater than one hour, and is usually comprised within the range 1-1.5 hours. The temperature of the acid environment treatment is higher than 0°C and is usually comprised within the range 10- 50°C, room temperature being preferable. The duration of the alkaline environment treatment is greater than one hour, and is usually comprised within the range 1-1.5 hours. The temperature of the alkaline environment treatment is higher than 0°C and is usually comprised within the range 10- 50°C, room temperature being preferable. Iron disulphide may be the one contained in the mineral pyrite. The reagent can be utilised in a dispersed form to be admixed to the material to be treated, or placed inside a column or container wherein the material to be treated is circulated forcibly. The method according to the present invention presents, besides the advantages explicitly and implicitly aforementioned, the advantage of preventing the formation of new toxic substances and above all, not being a thermodistructive method, of not generating new emissions, containing hydrochloric acid and carbon dioxide among other things. The method of the present invention can be advantageously adopted in the treatment of wastes of different origin, among which the ones hereinafter are indicated by way of explanation: - petrochemical industry tailings; - tailings deriving from craft and tertiary activities that imply the utilisation of chloroalkyls and chloroaromatics; - pitches and distillation tails of chlorinated solvents; - production wastes contaminated by polychlorodicoumarones, polychlorodibenzodioxins, active principles made of organic aliphatic and aromatic molecules chemically bound with halogens (chlorine, bromine, iodine). So far, only a general disclosure of the present invention was given. With the aid of the examples hereinafter, a more detailed description will now be given of its embodiments, directed towards making the objects, features, advantages and operative modalities of the present invention better understood. Example 1 An oily emulsion originated from a petrochemical plant with the composition hereinafter expressed as mg/1: Trans 1-2 dichloroethyl 0.96 Cis l-2 dichloroethyl 0.81 Chloroform 3.60 1-2 Dichloroethane 313.92 Trichloroethylene 0.16 1-1-2 Trichloroethane 2.40 is treated according to the invention with a mixture constituted of 33.3 % by weight Fe, 16.7 % Zn and 50 % FeS in a ratio of 3 g of mixture per 100 ml of oily emulsion. The post-treatment aqueous phase contains 0,18 mg/1 chloroform and 0.05 mg/1 1-2 dichloroethane. The post-treatment solid phase contains only 0.37 mg/1 1-2 dichloroethane. Therefore it is observed that in the aqueous phase the chlorinated products were abated from 321.85 mg/1 to 0.23 mg/1 (with a 99.93 % yield), whereas in the solid phase the chlorinated products were abated from 321.85 to 0.71 mg/1 (with a 99.88 % yield). Example 2 An oily emulsion originated from a petrochemical plant with the composition hereinafter expressed as mg/1: Trans 1 -2 dichloroethyl 2.30 Chloroform 6.00 1-2 Dichloroethane 470.00 Trichloroethylene 0.31 1-2-3 Trichloroethane 4.02 Perchloroethylene 0.24 o-xylene 0.43 is treated according to the invention with a mixture constituted of 75 % by weight Fe, 25 % Zn in a ratio of 3 g of mixture per 100 ml of oily emulsion. The post-treatment aqueous phase contains only 0,17 mg/1 chloroform and 0.13 ml/1 1-2 dichloroethane. The post-treatment solid phase contains only 0.31 mg/1 chloroform and 0.25 mg/1 1-2 dichloroethane. Therefore it is observed that in the aqueous phase the chlorinated and aromatic products were abated from 482.87 to 0.30 (with a 99.94 % yield) and from 0.43 to 0.00 mg/1 (with a 100 % yield), respectively, whereas in the solid phase the chlorinated and aromatic products were abated from 482.87 mg/1 to 0.56 mg/1 (with a 99.88 % yield) and from 0.43 mg/1 to 0.00 mg/1 (with a 100 % yield), respectively. Example 3 An artificial mix prepared in laboratory with water and solid sludge (about 70 %) and having the composition in mg/1 hereinafter: 1-2 Dichloroethane 729.94 Benzene 370.90 Trichloroethylene 825.47 Toluol 698.08 Perchloroethylene 1358.27 o-xylene 854.04 is treated according to the invention with a mixture constituted of 25 % by weight FeSO and 75 % FeS in a ratio of 3 g of mixture per 100 ml of the artificial mix to be treated. The post-treatment aqueous phase contains only 0.17 mg/1 1-2 dichloroethane. The post-treatment solid phase contains only 0.43 mg/1 1-2 dichloroethane, 0.01 mg/1 benzene and 0.18 mg/1 o-xylene. Therefore it is observed that in the aqueous phase the chlorinated and aromatic products were abated from 2913.68 mg/1 to 0.17 mg/1 (with a 99.99 % yield) and from 1923.02 to 0.00 mg/1 (with a 100 % yield), respectively, whereas in the solid phase the chlorinated and aromatic products were abated from 2913.68 mg/1 to 0.43 mg/1 (with a 99.99 % yield) and from 1923.02 mg/1 to 0.19 mg/1 (with a 99.99 % yield), respectively. Example 4 An artificial mix prepared in laboratory with water and solid sludge (about 70 %) and having the composition expressed in mg/1 hereinafter: Trans 1 -2-dichloroethyl 0.92 Cis 1-2 dichloroethyl 1.24 Chloroform 4.16 1-2 Dichloroethane 11.66 Benzene 0.76 Trichloroethylene 3.72 1-1-2 Trichloroethane 3.28 Toluol 0.70 Perchloroethylene 5.58 Ethylbenzol 0.98 p-xylene 0.91 o-xylene 0.99 is treated according to the invention with a mixture constituted of 16.7 % by weight Zn, 33.33 % by weight FeSO 4 , and 50 % FeS in a ratio of 3 g of mixture per 100 ml of the artificial mix. The post-treatment aqueous phase contains only 0.07 mg/1 trans 1-2 dichloroethyl, 0.13 mg/1 1-2 dichloroethane and 0.02 mg/1 trichloroethane. The post- treatment solid phase contains only 0.43 mg/1 trans 1-2 dichloroethyl, 0.86 mg/1 cis 1-2 dichloroethyl and 1.07 mg/1 1-1-2 dichloroethane. Therefore it is observed that in the aqueous phase the chlorinated and aromatic products were abated from 30.58 mg/1 to 0.22 mg/1 (with a 99.27 % yield) and from 4.34 mg/1 to 0.00 mg/1 (with a 100 % yield), respectively, whereas in the solid phase the chlorinated and aromatic products were abated from 30.58 mg/1 to 2.36 mg/1 (with a 96.28 % yield) and from 4.34 mg/1 to 0.00 mg/1 (with a 100 % yield), respectively.

Claims: C L A I M S 1. Method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that contain the, characterised in that the material to treat is made reacting - in an acid and/or alkaline environment, or viceversa - with a reagent selected from the group comprising zinc, iron, iron disulphide, ferrous sulphide, ferrous sulphate and mixtures thereof. 2. Method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that comprise them according to claim 1, wherein the acid environment treatment is carried out at a pH lesser than 6. 3. Method according to claim 1 or 2, wherein the acid environment is obtained by the addition of a mineral acid. 4. Method according to claim 3, wherein the mineral acid is selected from the group comprising sulphuric acid, hydrochloric acid and combinations thereof. 5. Method according to any one of the preceding claims, wherein the alkaline environment treatment is carried out at a pH greater than 8. 6. Method according to claim 5, wherein the alkaline environment is obtained with the addition of an alkaline or an alkaline earth base. 7. Method according to claim 6, wherein the alkaline or alkaline earth base is selected from the group comprising sodium hydroxide, potassium hydroxide, calcium hydroxide and combinations thereof. 8. Method according to any one of the preceding claims, wherein the treatment duration in an acid as well as in an alkaline environment is above one hour. 9. Method according to claim 8, wherein the treatment duration in an acid as well as in an alkaline environment is comprised within the range 1-1.5 hours. 10. Method according to any one of the preceding claims, wherein the treatment temperature in an acid as well as in an alkaline environment is higher than 0°C. 11. Method according to claim 10, wherein the treatment temperature in an acid as well as in an alkaline environment is comprised within the range 10-50°C. 12. Method according to claim 11, wherein the treatment temperature in an acid as well as in an alkaline environment is room temperature. 13. Method according to any one of the preceding claims, wherein the reagent is in dispersed form and is mixed to the material to be treated. 14. Method according to any one of the claims from 1 to 12, wherein the reagent is placed inside a column or container wherein the material to be treated is circulated forcibly. 15. Method according to any one of the preceding claims, wherein the iron disulphide is the one contained in the mineral pyrite. 16. Method for the demolition and the removal of halogenated and aromatic hydrocarbons from materials that contain them, as previously described, exemplified and claimed.

Inventors: BENNINI ALDO, BENNINI, ALDO
Applicants: BENNINI ALDO, KIROR B V, BENNINI, ALDO, KIROR B.V.
Application year: 2000
Main classification: A62D3
IPC codes: A62D3, A62D101