BG856Y1 - Means of rendering harmless of heavy metals, pesticides and organic pollutantsin the soil - Google Patents

Abstract

The invention relates to a method and means for rendering harmless of heavy metals, pesticides and organic pollutants in the soil by their binding in products not assimilated by the plants. By them reduction or an absence of heavy metals in the plants cultivated in polluted soils and the neutralization of the harmful effect of pesticides and other organic pollutants on the development of agricultural crops is ensured. The means is in the form of symmetrical or non-symmetrical block copolymers of the ethylene and propylene oxide of linear or branching chain and molecular mass from 1000 to 20000. They are surfactants of specific hydrophilic-hydrophobic balance. Due to their solubilization properties they interact with the organic pollutants in the soil, forming products not assimilated by the plants. Applied individually or in particular in combination with dithiooxamide or its derivatives, they sharply reduce or in practice stop the transition of heavy metals or polluted soils into the plants due to the formation of insoluble metal complexes. The process comprises the preparation of aqueous solutions of the said means of specified concentration which are introduced by single application in the soil by the methods of irrigation used in farming.

Description

Heavy metals, pesticides and organic pollutants in soil are used in agriculture to reduce the rate of passage of these harmful pollutants from soil to plants and from there to the entire food chain. Heavy metals and toxic organic compounds accumulate in humans and cause serious diseases, and some of the pollutants are carcinogenic and mutagenic.

BACKGROUND OF THE INVENTION

There are methods and means for purifying soils of heavy metals and organic pollutants, but most of them are only applicable under laboratory conditions or for small volumes of contaminated soil - for example, by acid washing the soil or by treating it with aqueous solutions of chemicals and following. liquid phase removal [1]. An aqueous solution containing two components - an acid and a salt (ammonium or an alkali metal or alkaline earth metal salt) is used as a heavy metal soil purification agent [2]. Electrochemical and electrokinetic methods for extracting lead from soil are known [3,4]. Phytoremediation is of practical importance for the recovery of heavy metals from contaminated soils [5]. This method is time-consuming and therefore more applicable to non-agricultural land.

Soil purification from organic pollutants can be carried out by microbiological methods [6]. There is a known method for the degradation of dioxins upon heating with polyethers or polyesters [7].

There is a method for bioelectrokinetic remediation of soils containing organic pollutants and heavy metals [8].

Due to the lack of a fast, efficient and accessible method and means of purification of soils from heavy metals and organic pollutants, there is a need to limit their harmful effects on humans and nature. This can be achieved by converting the pollutants into inert and insoluble in soil conditions that are not absorbed by the plants and do not pass into the groundwater.

The immobilization of heavy metals in soil can be accomplished by the addition of a sufficient amount of suitable anions (eg oxides, chlorides, sulfates, sulfides, phosphates, molybdates, etc.) to form insoluble salts with the metal ions. A major problem with this method is that in each soil there are competing cations other than contaminants that can react with the anions. Other means of immobilizing heavy metals and organic pollutants include solid adsorbents or reagents that are introduced into the soil - zeolites, bentonites, calcium oxide or hydroxide, and others [9,10]. In these cases, additional mechanical treatment of the treated earth sections is usually required. However, there is no information in the literature on the content of heavy metals or organic pollutants in cultivated plants grown on so treated soils.

Laboratory tests have shown that organic compounds (eg myoinositol-hexaphosphoric form) can be successfully used to immobilize lead, uranium, copper and nickel in soil [11], but there is also no indication of the content of metals in plants grown on these soils.

A method [12] known and known for the immobilization of heavy metals in soils and groundwater by a redox process. The method involves the application of two solutions - the first, with a pH of 3 to 5, containing ferrosulfate and sulfuric or phosphoric acid, destroying the metal complexes and converting the pollutants into insoluble compounds. The second solution, having a pH of 3 to 7 containing hydrogen peroxide and sulfuric or phosphoric acid, destroys the organic ligands. In this way, the pollutants are immobilized in the soil and do not pass into the groundwater. There are no data on the effect of this agent on soil organisms and plants.

There are no known means and methods of reducing the rate of passage of heavy metals, pesticides and other organic pollutants from soil into plants, as well as those that allow the cultivation of harmless agricultural produce on contaminated soil.

The technical nature of the utility model

The disposal of heavy metals, pesticides and organic pollutants in the soil is done by linking them to non-digestible plant products. Heavy metals are bound together in insoluble high molecular weight complexes, and the passage of pesticides and other organic pollutants is prevented from solubilizing them into micelles of polymers with specific surfactant properties.

The problem to be solved with the utility model is to reduce the rate of passage or practically stop the passage of heavy metals, pesticides and organic compounds from soil into plants.

This problem is solved by the agent of the present utility model, which comprises as active components symmetric or asymmetric block copolymers of ethylene 10 and propylene oxides, with a molecular weight of 1000 to 20 000 having the following general formulas:

wherein X and Y are -H or -CH ₃ , with XF Y, m and η being integers from 4 to 20 and p being an integer from 1 to 9; each of these copolymers being used alone or in combination with dithioxamides of the following general formula

in which R _p R-, R, and R ₄ may be different or identical substituents selected from hydrogen, acyclic (C 1 -C ₂ ) and cyclic (C _3-7 ) alkyl, aryl, alkylaryl substituents or derivatives thereof, and and nitrogen, sulfur and oxygen containing heterocycles and their derivatives, in aqueous solution.

The utility, according to the utility model, allows heavy soils and organic soil pollutants to be used for the production of harmless agricultural products.

The advantage of the agent is that it is introduced into the soil in the form of an aqueous solution, with a concentration of 0.1 to 1%, by the methods of irrigation used in agriculture alone or simultaneously is irrigation water.

Other advantages of the agent are its non-toxicity, its stimulating effect on plant development, as well as its properties to preserve the original structure of the soil and to retain moisture in it for a long period [13]. According to the utility model, the soil does not affect the soil microorganisms.

The degree of decrease in the passage of heavy metals from soil into plants depends on the concentration of dithioxamides and at the stoichiometric ratio the heavy metals are quantitatively retained in the soil. The degree of reduction of the passage of organic compounds and pesticides from soil into plants depends on the type of soil pollutants, on the composition and structure of the multiblock polyethers and on their concentration calculated per kilogram of soil.

Examples of implementation of the utility model

The following examples illustrate the utility model without limiting it.

Example 1.

The content of heavy metals in plants grown on highly polluted soils treated differently was investigated. For each of the vessel experiments, 200 g of contaminated with heavy metals was used in screened and fractionated soil. Immediately after planting the soil is irrigated once with 0.2%

NO- (CH ₂ -CH ₂ O) ₈ - (CH-CH, O) ₁₅ - (CH ₂ -CH ₂ O) ₈ - (CH-CH ₂ O) ₁₅ - (CH ₂ -CH ₂ O) ₇ - CH ₂ CH ₂ OH CH ₃ or with water containing the same multiblock polyether at the same concentration and 0.5 g.dnr ³ dithioxamide (100 mg dithioxamide per 1 kg of soil). Irrigation after sowing a control solution (400 mg of polyether per 1 kg of soil) on a symmetric 5-block copolymer of ethylene and propylene oxides with a molecular weight of about 3000 and formula

CH ₃ samples as well as subsequent waterings of all plants are carried out with water. The results of the study of the heavy metal content of plants are presented in Table 1.

Table 1. Content of heavy metals in plants grown on soil contaminated with heavy metals and treated as described in Example 1.

Metal Metal content (mg / kg) in untreated soil and plants Metal content (mg / kg) in plants in treated multiblock polyether (400 mg per 1 kg soil) Metal content (mg / kg) in plants when treated with multiblock polyether (400 mg per 1 kg soil) and dithiooxamide (lOOrng per 1 kg soil) soil plant Zn 166,0 79.3 35,7 1 Cd 2.38 1.84 0.72 follow Pb 1,25 1,05 0.82 follow

EXAMPLE 2 Lenin Oxides with a Molecular Weight of 2840 and Following the Effect of the 6-block Formula Asymmetric Copolymer of Ethylene and Propylene CH ₃ O- (CH-CH ₂ O) ₁₂ - (CH ₂ -CH ₂ O) ₈ - (CH- CH ₂ O) ₁₂ - (CH ₂ -CH ₂ O) ₈ - (CH-CH ₂ O) ₈ - (CH ₂ -CH ₂ O) ₆ -H

I I I

CH, CH, CH, on the development of tomatoes and eggplants grown in soil containing the pesticide Dicotex (MCPA) at a concentration of 50 mg per 1 kg of soil.

For vascular testing, sifted and fractionated soil, of alluvial-meadow type, weighing 200 and 500 g, containing Dicotex at the indicated concentration was used. Immediately after sowing the plants, the soil is watered with 0.2% aqueous six-block polyether solution (400 mg per 1 kg of soil). The next waterings are with water.

Plants grown in soil treated in this way develop normally.

In plants grown in soil containing Dicotec and watered with water alone, chlorosis is observed, which develops into leaf necrosis, followed by complete plant death.

Example 3.

Under the conditions of Example 2, phytotoxicity was investigated in wheat causing residues of the pesticide Afalon. Irrigation of contaminated soils with 0.3% aqueous solution (600 mg per 1 kg soil) of a four-block asymmetric copolymer of ethylene and propylene oxides with molecular weight 2650 and formula

CH ₃ -O- (CH-CH ₂ O) _{| 5} - (CH ₂ -CH ₂ O) _{| 0} - (CH-CH ₂ O) ₁₅ - (CH ₂ -CH ₂ O) ₁₀ -H

CH ₃ CH ₃ has been shown to significantly stimulate the development of wheat by non-digestible plants, in comparison with counterparts, characterized by premature untreated polyether samples. symmetrical or asymmetrical multibeam 1 <linear polyethers with linear or branched

Claims (4)

Pateite claims ^1J """molecular chain, molecular weight from 1000 to 1. A means of disposal for the heavy 20,000 having the following general formulas: metals, pesticides and organic pollutants HO- (CHCHzO) m - {(CHCH ₂ O) n- (CHCH ₂ O) m] p-H I II x γx CH3O - {(CHCH ₂ O) m- (CHCH ₂ O) Jp-H II xY XY II H - [(OCHCH ₂ ) n- (OCHCH ₂ ) _n Jp \ YX II [(CH 2 CHNOCH CH 2 OH ^ rH / NCHjCHzN / H-COSH-N-H-N-H-p II xY \ [(CH ₂ CHO) m- (CH ₂ CHO) n] pH II XY where X and Y are -H or -CH ₃ , with X * Y, m and η being integers from 4 to 20 and p being an integer from 1 to 9; each being used alone or in combination with dithiooxamide or its derivatives of the following general formula wherein R _p Rj, R ₃ and R ₄ may be the same or different substituents selected from hydrogen, acyclic (C, ₁₂ ) or cyclic ( C _{3 7} ) alkyl, aryl, alkylaryl substituents or derivatives thereof, as well as nitrogen-, sulfur- or oxygen-containing heterocycles or derivatives thereof, in aqueous solution. Method for introducing the agent according to claim 1 into the soil, characterized in that a 0.1 to 1% aqueous solution of the agent is introduced into the soil by any of the agricultural irrigation methods used. An agent according to claim 1, characterized in that it is introduced into the soil in an amount stoichiometric to that of the heavy metals therein. An agent according to claim 1, characterized in that it is introduced into the soil in amounts corresponding to its solubilizing capacity with respect to pesticides and other organic pollutants, most commonly from 300 to 500 mg per 1 kg of soil.