RU2638855C1 - Method of producing sorbent for water surface purifying from oil and oil products - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: fibrous cellulosic material is subjected to preliminary vacuum degassing and dehydration in vacuum impregnated with a prepared solution of tetrachloroethylene with 0.4-0.5 wt % of oxidized atactic polypropylene. Atactic polypropylene is oxidized for 4 to 6 hours at 180-250°C and dissolved in tetrachlorethylene. After impregnation, the rest of the solution is drained and returned to the recycling of the impregnation process. The impregnated material is vacuum dried to a constant weight. The pumped vapours are passed through a water seal filled with the solution used for the impregnation, condensed and recycled to the impregnation process.

EFFECT: producing a hydrophobic sorbent with improved performance properties.

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Description

The invention relates to a technology for the production of sorbents for cleaning the aquatic environment from oil and oil products during their accidental or emergency spills, as well as for the treatment of wastewater contaminated with oil and oil products.

A known method of producing a sorbent of petroleum products (RF patent No. 2071828, B01J 20/22, publ. 01/20/1997), including processing the carrier with a solution of active organic substances. Fibrous natural or synthetic material is used as a carrier, and solutions of alkyl carboxylic acids, higher aliphatic alcohols, their esters, polyolefins or paraffins in an organic low-boiling solvent selected from the class of hydrocarbons, halogenated hydrocarbons, ethers, sulfoxides are used as a solution of organic matter. The treatment is carried out at room temperature for 10-60 minutes at a concentration of active organic matter in solution from 0.1 to 1.0 wt. %, and after processing the sorbent is dried to constant weight at room temperature. This method does not provide repeated use of the sorbent in the collection of petroleum products, since the active substance applied to the carrier is easily washed off with oil and petroleum products.

A known method of producing a sorbent for water purification from oil products and heavy metals (RF patent No. 2132226, B01J 20/06, B01J 20/22, publ. 06/29/1999), including processing the fibrous carrier with titanium tetrachloride, followed by hydrolysis with water and drying. As the fibrous carrier use cellulose-containing material. Titanium tetrachloride is used in the form of its 2-7% solution in hydrocarbons C5-C7. The process is carried out to the content of titanium dioxide in the sorbent from 5 to 15 wt. % In this method, a combustible solvent is used. The process of obtaining the sorbent is complicated, since it is multi-stage. The resulting sorbent does not have buoyancy and therefore is not suitable for collecting oil from water surfaces.

Closest to the proposed technical solution is a method of producing a sorbent for collecting oil and oil products from the water surface (RF patent 2463106, B01J 20/30, publ. 10.10.2012), which consists in hydrophobization of fibrous cellulosic material with a solution of oxidized atactic polypropylene in tetrachlorethylene and subsequent drying hot air to constant weight. The presence of carboxyl groups in oxidized atactic polypropylene makes it possible to create a strong bond with cellulose due to the formation of a hydrogen bond between the carbonyl groups of the cellulose and the carboxyl groups of the polymer, which ensures high resistance of the sorbent to washing out the polymer from it with oil products and high hydrophobicity of the sorbent. In addition, oxidized atactic polypropylene forms cluster-type compounds with the cellulose surface, which significantly increases the sorption properties of natural fibers. These properties make it possible to ensure multiple use of the sorbent. In this method of producing the sorbent, the conditions for the preparation of fibrous cellulosic material for impregnation are not defined. Prior to processing, the fibrous cellulosic material has hydrophilic properties. During storage and transportation, it retains water, which closes micropores in the cellulosic material and does not allow to ensure the maximum quality of impregnation of the material with tetrachlorethylene modified with oxidized atactic polypropylene. Due to the low degree of solubility of tetrachlorethylene in water - 0.04 wt. %, tetrachlorethylene during the impregnation process cannot penetrate into micropores blocked by water. In this method of manufacturing the sorbent, a method of drying the treated cellulosic material with hot air at a temperature of 80-100 ° C, followed by condensation in the heat exchangers of the exhaust vapors of tetrachlorethylene with the oxidized atactic polypropylene dissolved in it, is used. The specified method for trapping the vapor of a solution of oxidized atactic polypropylene in tetrachlorethylene from a stream of hot air cannot prevent the emission of tetrachlorethylene into the atmosphere, which decomposes under the influence of sunlight to produce toxic phosgene.

The objective of the invention is to increase the safety of non-waste technology for the production of hydrophobic fibrous sorbent, increase the hydrophobic properties of the sorbent, increase the sorption properties of the sorbent in relation to oil and oil products, improve the regenerative properties of the sorbent to maintain its high sorption ability in relation to sorbed products.

The problem is solved due to the fact that in the proposed method for producing a sorbent for cleaning water and the earth’s surface and underwater environment, as well as in the prototype, hydrophobization of the fibrous cellulosic material with a solution of atactic polypropylene in tetrachlorethylene is carried out, while the cellulose material is preliminarily prepared by vacuum degassing and dehydration, impregnate the cellulosic material and subsequent vacuum drying the resulting sorbent to its constant weight, trap idrozatvore exhaust during vacuum drying a solution of vapors and return them to the recycle of the impregnation process.

According to the invention, atactic polypropylene is oxidized at a temperature of from 180 to 250 ° C. for 4 to 6 hours, dissolved in tetrachlorethylene and 0.4-0.5 wt. % solution of atactic polypropylene in tetrachlorethylene. The fibrous cellulosic material is subjected to preliminary vacuum degassing and dehydration for 10-60 minutes under vacuum of 0.01-0.15 bar in a sealed container. In the same tank, subsequent impregnation of the material is carried out with a prepared solution of atactic polypropylene in tetrachlorethylene. After impregnation, the excess solution is drained and returned to the recycling of the impregnation process. The impregnated material is subjected to vacuum drying for 10-60 minutes under vacuum with a depth of 0.01-0.15 bar. Vacuum-dried vapors are passed through a water trap, which is filled with a solution of atactic polypropylene in tetrachlorethylene intended for impregnation of cellulosic material, the vapors are condensed in a water trap and returned to the recycling of the impregnation process.

As fibrous cellulosic material, batting, cotton wool or cotton waste can be used.

This method of producing a sorbent for cleaning the water and the earth’s surface and the underwater environment allows one to obtain a sorbent that has a high sorption ability with respect to oil and oil products in the presence of water and a high ability to retain absorbed oil and oil products. Such a sorbent has high hydrophobicity and buoyancy, is capable of multiple mechanical and mechanical-vacuum regeneration (up to 50 or more regeneration cycles) and retains high sorption qualities after the regeneration process.

The hydrophobic properties of the sorbent allow it to be used to collect oil and oil products under water. Oil and oil products removed during sorbent regeneration can be returned to their consumers.

The sorbent can be disposed of by biodegradation methods, burning in furnaces and other known methods.

Based on the sorbent, special oil-absorbing products can be made - mats, napkins, booms. The main technological element for the production of these products is our proposed method for producing the sorbent.

The listed set of sorption-protective products provides nature users with a practical opportunity to provide preventive measures to protect the environment, quickly and timely respond to both standard and possible emergency situations that arise during the production, transportation, processing and use of oil and oil products, and provides the opportunity the use of the listed products from the sorbent in technological complexes for wastewater treatment from oil and oil products pollution with return the consumer of sorbed products.

Table 1 presents data on the effect of temperature and duration of oxidation of atactic polypropylene on the capacity of the sorbent.

Table 2 shows the values of the sorbent capacity depending on the number of regeneration cycles for two types of regeneration - mechanical extraction of absorbed oil in a centrifuge and mechanical extraction of absorbed oil in a centrifuge with final vacuum drying of the sorbent.

Example

10 g of atactic polypropylene are heated in a reactor to 240 ° C and air is passed through the polymer melt with stirring for 4-6 hours. Then the air supply is stopped, the reaction mass is cooled to 80 ° C and dissolved with 2500 g of tetrachlorethylene with stirring. The solution was cooled to room temperature.

Cotton batting, in the amount of 200 g, is dehydrated and degassed for 20 minutes under a vacuum of 0.1 bar in an airtight steel container. Further, without violating the tightness of the tank, a prepared solution of oxidized atactic polypropylene in tetrachlorethylene is poured into it until the pressure in the tank is equalized to normal conditions. Impregnation is carried out at normal temperature for 10-15 minutes. After the impregnation is completed, the solution of atactic polypropylene in tetrachlorethylene is drained from the sealed container.

In a sealed container with impregnated batting in it, a vacuum of 0.1 bar depth is created and the batting is vacuum dried at normal temperature for 20 minutes.

The vented vapors of tetrachlorethylene with atactic polypropylene dissolved in it are passed through a water trap which is filled with a solution of atactic polypropylene in tetrachlorethylene identical in composition to the trapped vapors and ensure complete dissolution of the exhaust vapors in this solution to prevent the emission of solution vapors into the atmosphere.

The obtained sorbent after the end of vacuum drying in an amount of 100 g was examined for oil sorption. The remaining 100 g of the sorbent is examined for the influence of the method of regeneration of the sorbent on its indicators of oil sorption. To do this, 5 liters of water and 5 liters of oil are poured into a container of 12 liters and mix them. 2 samples of sorbent are placed on the surface - sample No. 1 and sample No. 2 of 50 g each and incubated for 10 minutes, the sorbent is removed, the excess oil is drained for 1 minute. Both samples of the absorbed oil sorbent are weighed. The weight difference for each sample of the sorbent before and after oil sorption determines the weight of oil sorbed by each sample. Sample No. 1 of the sorbent is squeezed by centrifugation in a laboratory centrifuge and used for further tests to collect oil. Sample No. 2 of the sorbent is squeezed out by centrifugation in a laboratory centrifuge and vacuum dried in a separate container for 15 minutes under a vacuum of 0.1 bar depth.

Then, after each regeneration of the samples, performed for the samples by pressing or spinning followed by vacuum drying, repeat the entire described cycle of the process of collecting and determining the weight of sorbed oil for each sample.

The process of regeneration of the sorbent samples is carried out before each subsequent study of the sorption ability of the samples, preserving for sample No. 1 the method of regeneration by mechanical extraction of the sorbent, and for sample No. 2, the method of regeneration by mechanical extraction followed by vacuum drying of the sorbent.

The results of the influence of the oxidation conditions of atactic polypropylene and its content in a tetrachlorethylene solution on sorption by an oil sorbent are shown in Table 1.

The results of the effect on the sorption capacity of the sorbent during its multiple regeneration (batting is impregnated with a 0.4 wt.% Solution of atactic polypropylene oxidized at 240 ° C for 4 hours) for two different methods of sorbent regeneration: by mechanical extraction of the absorbed oil in a centrifuge and by mechanical extraction of the absorbed oil in a centrifuge with the final vacuum drying of the sorbent are shown in table 2.

The proposed method for producing the sorbent is implemented on standard equipment for chemical production. For the stage of oxidation of atactic polypropylene, a stainless steel reactor was used, equipped with a mechanical stirrer and heated to 300 ° C. Obtaining a solution of oxidized atactic polypropylene in tetrachlorethylene is carried out in the same reactor with mechanical stirring in tetrachlorethylene of the polypropylene oxidation product after it has been cooled.

The stock of the solution of oxidized atactic polypropylene in tetrachlorethylene, intended for the impregnation of cellulosic material, is stored in a sealed container made of stainless steel.

Degassing and dewatering of fibrous cellulosic material, its impregnation and final vacuum drying of the material are carried out in the same sealed stainless steel tank, which can withstand repeated depression up to 1-2 bar. To create a vacuum in the tank during vacuum degassing and dehydration of the fibrous cellulosic material and during the final vacuum drying of the obtained sorbent, a standard vacuum pump is used.

The water trap is made of stainless steel and filled with a solution of oxidized atactic polypropylene in tetrachlorethylene, which is used to impregnate fibrous cellulosic material. It is possible to divert part of the liquid sealant fluid into the recycling of the impregnation process.

A standard liquid pump is used to pump a solution of oxidized atactic polypropylene in tetrachlorethylene between containers.

Claims (1)

A method of producing a sorbent for purifying an aqueous medium by hydrophobizing a fibrous cellulosic material by impregnating it with a 0.4-0.5 wt.% Solution of atactic polypropylene, oxidized at a temperature of from 180 to 250 ° C for 4 to 6 hours, in tetrachlorethylene, characterized in that the used fibrous cellulosic material is subjected to preliminary vacuum degassing and dehydration for 10-60 minutes under vacuum with a depth of 0.01-0.15 bar in a sealed container in which subsequent impregnation of the material is carried out, after impregnation the solution is drained and returned to the recycling of the impregnation process, the impregnated fibrous cellulosic material in the same sealed container is vacuum dried for 10-60 minutes under a vacuum of 0.01-0.15 bar in depth, the vapors leaving during vacuum drying are passed through a water seal, which is filled with the solution used for impregnation, the exhaust vapors are condensed and returned to the recycling of the impregnation process.