RU2581402C2 - Method of producing fine sorbent for oil and oil products from low- and high-density polyethylene wastes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing fine sorbent for oil and oil products includes preparing a solution of polyethylene wastes while heating and mixing in toluene; adding cold water to the hot solution to cool the solution to 30-50°C; simultaneously crushing the formed wax-like mass and evacuating; filtering and drying the sorbent after distilling toluene.

EFFECT: high sorbent output, simple method, shorter duration of the method and low power consumption.

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Description

The invention relates to the field of environmental protection and is intended to solve two major environmental problems: recycling of polymer waste, as well as the elimination of emergency oil and oil product spills and the treatment of industrial effluents of oil refining enterprises.

It is known that the use of synthetic (polymer) sorbents (Arena V.Zh., Gridin OM, Effective sorbents for the elimination of oil spills. // Ecology and industry of Russia. - 1997. - is the most effective for the elimination of oil spills from the surface of water areas. No. 2. - S. 32-37). These sorbents, in comparison with inorganic and natural sorbents, have a higher sorption capacity, and the possibility of their production from secondary raw materials allows solving the problem of recycling polymer waste. Such sorbents include non-woven fabrics formed from polypropylene, polyethylene, polyethylene terephthalate, polystyrene, etc. fibers; sponge or granular polyurethane; crumb rubber obtained from the processing of worn-out car tires; hollow polymer microspheres; compositions consisting of crumb rubber, powdered polyethylene and crushed cellulose.

The main disadvantages of these sorbents are their high cost, due to the multi-stage process of their production, and the use, in some cases, of primary polymer raw materials.

There is also a known method of isolating a powder from solutions of polyolefins in organic solvents, which is obtained by environmentally friendly technology, which excludes, in contrast to the traditional use of large quantities of an expensive precipitant (RF Patent No. 2194719, publ. 2002).

This method involves cooling the polyolefin solution to room temperature, grinding the resulting paraffin-like mass, mixing it with water, heating the resulting mixture to a temperature not exceeding the melting temperature of the polymer in the presence of an organic solvent. The polymer is isolated by evacuating the mixture until the solvent is completely distilled off, which is removed from the system along with water vapor. Then the powder is filtered off from water and dried. The organic solvent and water collected in the condensate collector are separated by settling and decantation.

However, the powder obtained by this method has a relatively large particle size of 1000 μm or more, which reduces its sorption capacity, which is only 1-2 g / g and, consequently, the effectiveness of its use as a sorbent. In addition, the method does not provide for the possibility of obtaining powdered sorbents from waste.

There is also a method of producing a sorbent for cleaning various surfaces from spills of oil and oil products (RF patent 2107034, publ. 1998). According to this method, the sorbent is obtained from waste generated during the combustion of pulverized coal, followed by treatment with a water repellent. As a water-repellent agent, high-molecular-weight wastes from the production of the wood chemical or petroleum industry, such as rosin, tall oil, latex, paraffin, ceresin, are used. The treatment is carried out with an aqueous emulsion or an aqueous solution of a hydrophobizing agent at a temperature of 40-96 ° C, followed by drying at a temperature of 100-120 ° C to constant weight.

The disadvantages of this method are the complexity of the technology and its hardware design. In addition, for the manufacture of water repellents it is necessary to use special emulsifiers - surfactants. In addition, there is a large spread in xenosphere size (from 30 to 400 microns), which requires their separation into fractions.

The closest technical solution to the claimed is a method for producing a finely dispersed sorbent of oil and oil products from high molecular weight production waste (RF Patent 2252071, publ. 2005).

The method consists in carrying out the following operations.

1. Preparation of the solution. For this purpose, waste of low or high density polyethylene (LDPE or HDPE) is used, for example, pre-crushed agricultural or packaging film, used bottles, used bottles, waste from the cable industry, runners and grooves. This waste is dissolved in an organic solvent, for example toluene, n-xylene, heptane at a temperature of 90 ° C and vigorous stirring for 30 minutes. This solution is prepared with a polymer concentration of 20-35% of the mass.

2. Cooling the solution.

It is carried out in air to room temperature. In this case, a mixture of a paraffin-like substance with insignificant mechanical strength and an organic solvent is formed.

3. Adding to the resulting mixture of water in a ratio of 1: 1.

4. Grinding paraffin-like substance.

This is carried out in the presence of water and an organic solvent by high-speed stirring for 3-5 minutes at a stirrer speed of 2500-3000 rpm.

5. Heating the mixture.

Heating is carried out to a temperature not exceeding more than 10 ° C the melting temperature of the polymer in the presence of a large amount of solvent used to prepare the solution. For example, when using toluene, the mixture is heated to 52 ° C in relation to LDPE, to 62 ° C in relation to HDPE.

6. Evacuation of the mixture.

It provides a lower boiling point of the solvent and lasts until it is completely distilled. In this case, the residual pressure in the reactor is 15-40 mm Hg.

7. Filtration of the sorbent powder from the remaining water.

8. Dry the powder at 100 ° C to constant weight.

The presence of water intensifies the process by increasing the evaporation surface of the crushed paraffin-like mass, caused by the bubbling of water vapor through its layer, and makes it fire and explosion safe.

The condensation of the vapors of the jointly distilled off solvent and water at the stage of evacuation is carried out in a refrigerator at a temperature of 0 ° C. The same temperature is maintained in the vapor condensate collector. Maintaining the indicated temperature in the refrigerator and vapor condensate collector is necessary to prevent irretrievable loss of solvent.

The water and solvent collected in the condensate collector are sedimented and separated by decantation. The recovered solvent is reused in the process, and the recovered water is consumed for technological needs.

Thus obtained polymer powder is used as a sorbent of oil and oil products.

However, the method is not effective enough, since:

- the sorbent yield is small - not higher than 60% of the amount of polymer waste used;

- the method is long and complicated due to multi-stage;

- characterized by high energy consumption spent at the stages of cooling the solution and subsequent heating of the mixture of paraffin-like substances, solvents and water;

- the sorbent has a limited scope due to a fixed particle size of 35 ± 10 microns.

SUMMARY OF THE INVENTION

The objective of the invention is to increase the efficiency of the method by increasing the yield of the target product, simplifying the method, reducing energy costs and obtaining a sorbent with the desired particle size.

The problem is solved by a method of producing a finely dispersed sorbent of oil and oil products from low and high density polyethylene wastes, including the preparation of a solution of polyethylene wastes in toluene by heating and stirring, cooling it, adding cold water, grinding the resulting paraffin-like mass, evacuating, ensuring solvent distillation at a low temperature , filtration and drying, in which water is added directly to the hot prepared solution until it is cooled to 30-50 ° C , grinding the paraffin-like mass and evacuation begin at the same time, and the crushed polymer is filtered off after the final distillation of toluene.

The invention can significantly increase the efficiency of the method, since:

- provides 100% sorbent yield of the amount of polymer waste used;

- the method has become simpler and less lengthy by reducing the number of stages - from 8 to 5;

- significantly reduced energy costs;

- it became possible to obtain a powder with the required particle size. This greatly expands the scope of the obtained powders, for example, in the following areas:

- in the manufacture of powder paints (50-100 microns);

- as a binder in the manufacture of finishing construction (particleboard, fiberboard, lining) materials (100-200 microns);

- in the clothing industry as hot melt adhesive (100-300 microns);

- for lining pipes (100-300 microns);

- in the cosmetic industry in the manufacture of scrubs (200-400 microns);

- in the construction industry in the manufacture of road bitumen mastics (200-800 microns).

Information confirming the reproducibility of the invention

To implement the method, the following materials can be used.

Agricultural waste, packaging and cling film, waste from the cable industry, sprues and grooves generated in the plastics processing industry can be used as polyethylene waste.

Toluene TU 2631-002-29483781-2005 is used as an organic solvent.

The method is implemented by sequentially carrying out the following operations:

1. Preparation of the solution. To do this, the waste polyethylene is dissolved in toluene at 85-95 ° C and vigorous stirring at a speed of rotation of the mixer 560 rpm The working solution is prepared with a polymer concentration of 10-30% of the mass.

2. Cooling the solution.

This stage is carried out by adding to the hot solution of cold water in an amount that ensures its cooling to 30-50 ° C. This forms a mixture of paraffin-like mass, toluene and water.

3. Grinding and evacuation.

These operations are carried out simultaneously by high-speed stirring for 3-5 minutes at a stirrer rotation speed of 2500-2800 rpm and lowering the pressure in the reactor to 40-100 mm Hg. until the solvent is completely distilled from the mixture.

4. Filtration of the sorbent powder from the remaining water.

5. Drying the powder at 90-100 ° C to constant weight. The powder is also of high quality, since the sorption capacity of the powder with a particle size of 35-50 μm corresponds to the value of this parameter for the powder obtained by the method described in the prototype, and is 3.5-4.0 g / g

Example 1. The crushed waste packaging plastic film in the amount of 216 g is dissolved in 1 l of toluene at a temperature of 85 ° C with stirring at 560 rpm The concentration of the solution is 20% of the mass.

3.3 liters of cold water are added to the hot solution. The temperature of the mixture drops to 30 ° C. A mixture of paraffin-like mass, toluene and water was formed. The pressure in the reaction apparatus is lowered to 80 mm Hg. and at the same time turn on a high-speed mixer (2800 rpm) and continue stirring for 4 minutes, and evacuation until complete distillation of toluene. After that, the resulting powder is filtered off from water and dried at a temperature of 90 ° C. Got a powder in an amount of 216 grams with a particle size of 35-45 microns. The sorption capacity of the obtained powder is 3.5 g / g.

Example 2. The crushed waste packaging plastic film in an amount of 371 g is dissolved in 1 l of toluene at a temperature of 85 ° C with stirring at 560 rpm The concentration of the solution is 30% of the mass.

2.5 liters of cold water are added to the hot solution. The temperature of the mixture drops to 50 ° C. A mixture of paraffin-like mass, toluene and water was formed. The pressure in the reaction apparatus is reduced to 80 mm. Hg and at the same time turn on a high-speed stirrer (2500 rpm) and continue stirring for 4 minutes, and evacuation to complete distillation of toluene. After that, the resulting powder is filtered off from water and dried at a temperature of 90 ° C. Received a powder in an amount of 371 g with a particle size of 200-300 microns.

This powder can be used in the clothing industry as a hot glue; for lining pipes; in the cosmetic industry in the manufacture of scrubs; in the construction industry in the manufacture of road bitumen mastics.

Claims (1)

A method of producing a finely dispersed sorbent of oil and oil products from low and high density polyethylene wastes, including preparing a solution of polyethylene wastes in toluene by heating and stirring, cooling it, adding cold water, grinding the resulting paraffin-like mass, evacuating to distill off the solvent at a low temperature, filtering and drying, characterized in that the water is added directly to the hot prepared solution until it is cooled to 30-50 ° C, grinding steam fin-like mass and evacuation begin at the same time, and the crushed polymer is filtered off after the final distillation of toluene.