Method for neutralisation of soil pollutants

FIELD: chemistry.

SUBSTANCE: invention relates to agriculture. According to the disclosed method, a decomposer which is susceptible to electromagnetic waves is first dispersed on the soil surface, followed by exposure of the treated area to microwave radiation. The decomposer used is a substance in liquid form or solutions which release atomic oxygen under the effect of microwave radiation, specifically hydrogen peroxide or sodium peroxydisulphate solution.

EFFECT: method enables to neutralise chemical compounds of different classes, including low-polarity compounds, as well as weeds and pests, owing to chemical destruction of pollutants when the soil is exposed to microwave radiation.

2 cl, 5 ex

The invention relates to the field of decontamination of soil pollutants of different nature and can be used for reclamation works for elimination of consequences of environmental accidents associated with the leakage of toxic compounds, as well as in agriculture for weed control and different pests.

To delaborated substances include inorganic compounds such as nitrates, chromates and dichromate; organic compounds, such as oil, pesticides, herbicides, fungicides and so on; combat toxic substances - esters Ferapontovo acid and similar compounds.

The traditional way of neutralizing soil pollutants is the removal of topsoil and subsequent high-temperature processing in kilns (RF 2007132141).

This method has the following disadvantages. The removal of soil and subsequent arrival at the sampling location is very unprofitable and sell only in areas with developed infrastructure, that is, where there are roads and kiln. In addition, the slag is not fertile and must be disposed of, which is associated with additional costs.

There is a method of microwave treatment of soil contaminated with PCBs, consisting of sublimation of pollutant (in particular, polychlorbiphenil) with subsequent is the vapor pressure of (CN 1850371, VS 1/06).

This method has the following disadvantages:

1) during exposure to contaminated soil by microwave radiation of water evaporation, the pairs which carry the PCBs from the soil without any destruction. Chilled pair of contaminant deposited and penetrate back into the soil;

2) is processed only from PCBs and there is no neutralization of other pollutants, both organic and inorganic nature.

Also there is a method of decontamination of soils contaminated residues of toxic substances in the form of arsenic compounds by heating the soil microwave energy with a frequency of 915 MHz radiation (EN 2308104, G21F 9/32).

The disadvantages of the method include the following:

1) during exposure to contaminated soil by microwave radiation evaporation of arsenic compounds, the vapors of which, after cooling, deposited and penetrate back into the soil.

2) the method involves processing only from arsenic compounds without affecting the other, not less dangerous pollutants, both organic and inorganic nature.

Known methods closest to the proposed to the technical essence and the achieved result is a method of decontamination of soil pollutants, namely, that previously in the soil making and evenly distribute MOSPRIME is output to electromagnetic waves in matter, then make the exposure of the treated area with microwave radiation - electromagnetic waves with a frequency of 2450 MHz and a power of 1 KW or more during the time necessary for transfer of the contaminants in the inactive form (CN 101513643, 2009).

However, in this decision, the energy of the microwave radiation is spent on heating of the soil containing the contaminant and the substance susceptible to microwave radiation, and the process of neutralization is thus due to evaporation, decomposition or commit substances pollutant at an elevated temperature.

In addition, using the known solution of the reagent in dry form weakens the process of chemical degradation on the reasons for the low rate of diffusion and low thermal conductivity of the environment.

These factors reduce the effectiveness of the remediation of contaminated soils, since the implementation of the chemical decomposition of pollutants requires large power consumption due to continuous processing to achieve the desired degree of neutralization.

The present invention is the task of developing a method for abatement of pollutants, providing an intensification of chemical degradation of pollutants during microwave exposure on the soil due to the generation of atomic oxygen by the decomposition of liquid reagent destructor, which is the active oxidant, and, as a consequence, the reduction of energy consumption and processing time.

This object is achieved in that in the method for abatement of pollutants in soils previously dispersed on the soil surface reagent destructor susceptible to electromagnetic waves, with subsequent exposure of the treated area with microwave radiation, and as a reagent-destructor use of the substance in liquid form or solutions that produce atomic oxygen under the action of mikrovolnovogo radiation.

And also the fact that as substances that produce atomic oxygen under the action of mikrovolnovogo radiation, use hydrogen peroxide or a solution of peroxodisulfate sodium.

The method consists in the following.

Before disposal in the soil making the reagent-destructor, spraying it into the soil in quantities depending on the content of ecotoxicants.

As reagent-destructor use chemical compound susceptible to microwave radiation at a given frequency, undergoes irreversible changes and contributing to the neutralization of the contaminant. This reagent can be, for example, a solution of hydrogen peroxide concentration of from 5 to 30% (depending on the concentration of the pollutant), that the interaction of the tvii with microwave radiation is decomposed into atomic oxygen and water. Atomic oxygen, representing the active oxidant reacts with the contaminant and translates it into an inactive form. Hydrogen peroxide can be successfully applied for the treatment of inorganic toxicants, such as dichromate. Dichromate or chromate, featuring a large redox potential under the influence of microwave radiation oxidizes hydrogen peroxide, going in low-toxic trivalent form of chromium.

After the solution will be absorbed into the soil, carry out the procedure neutralization using a mobile microwave installation. The exposure time depends on the density, moisture content, composition and dielectric properties of the soil and is determined empirically. Mobile unit is a device consisting of a magnetron, a waveguide, power supply and other accessories. The plant is assembled on the basis of the vehicle and other mobile tools to ensure a continuous process of neutralization. The power plant is operated from the generator of the vehicle. Contaminated soil can be exposed to electromagnetic waves with a frequency in the range of 2000-6000 MHz and the radiated power is not less than 1 kW. Chemical compounds containing such functional groups as hydroxyl, carboxyl, is mine, sulfona and other, as well as connections, soderjashie metals such as iron, Nickel, chromium, arsenic, tungsten, and others, are susceptible to microwave radiation. The interaction of chemical compounds containing these groups, with microwave radiation leads to the transition of the substance in the excited state and subsequent destruction. Also, chemical destruction of substances is due to thermal influence from the soil, as some of its components are susceptible to microwave radiation. When the power exceeding 1 kW, some components of the soil can be heated to a temperature greater than 1000°C.

Example 1. Neutralization neorganicheskoi pollutant - potassium dichromate

For neutralization of dichromate concentration of not less than 1 g /kg, in soil making the reagent-destructor is not less than 10 ml of hydrogen peroxide solution concentration of 10%, and then irradiated with microwave radiation of a frequency of 2450 MHz and a power of 1000 W for 3 min Dichromate quantitatively transferred to a much less toxic compounds chromium (III).

Example 2. Disposal of organic pollutant - O,O-Dimethyl-S-(1,2-diabetiker)dithiophosphate, which is an insecticide.

For neutralization of soil with O,O-Dimethyl-S-(1,2-diabetiker)dithiophosphate concentration of not less than 1 g/ kg of soil in the soil contribute reagent-destructor - at least 5 ml of 10% hydrogen peroxide solution, and then exposed to microwave irradiation frequency 5800 MHz and a power of 1200 W for 3-5 minutes. The specified connection is quantitatively decomposed into a mixture of low molecular products.

Example 3. Disposal of hydrocarbon contamination

In the soil contribute to the solution of peroxodisulfate sodium concentration of 20%. Then, for neutralization of residual oil concentration of not less than 5 g/ kg, the soil is exposed to microwave radiation of a frequency of 2450 MHz and a power of 1200 W for 3 minutes. The concentration of harmful substances is reduced in 3 times, the degradation products are nizkomolekulyarnye volatile hydrocarbons, CO₂and coke.

Example 4. The clearance of weeds

For the destruction of weeds, sprouts in the soil making the hydrogen peroxide solution concentration of 10% and then irradiated with microwave radiation with a frequency of 2450 MHz. The radiation power should not be less than 1200 watts, processing more than 3 minutes.

The examples illustrate the proposed method, but do not limit its application.

The proposed method allows to neutralize common soil pollutants due to their chemical decomposition by irradiation with microwave radiation, using liquid chemicals-destructors troop atomar the second oxygen in the irradiation process.

1. Method of decontamination of soil pollutants, namely, that pre-dispersed on the surface of the soil reagent destructor susceptible to electromagnetic waves, with subsequent exposure of the treated area with microwave radiation, and as a reagent-destructor use of the substance in liquid form or solutions that produce atomic oxygen under the action of microwave radiation.

2. The method according to claim 1, characterized in that substances that produce atomic oxygen under the action of microwave radiation using hydrogen peroxide or a solution of peroxodisulfate sodium.