RU2352388C1 - Method of obtaining sorbent for water purificaion - Google Patents

Abstract

FIELD: environment protection.

SUBSTANCE: invention relates to environment protection and can be used for water and soil purification from phenol, oil and oil products, metal ions. Claimed is method of obtaining sorbent for water purification based on natural polymer, water processing being carried out with polymer-colloid complex, obtained by mixing chitosan solution with diluted acetic acid and 5-10% water solution of gelatin, with their weight ratio to chitosan to gelatin 1:(1.8-2.2) with further filtration and drying.

EFFECT: increase of sorptive characteristics and obtaining non-toxic, biodegradable sorbent.

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Description

The invention relates to environmental protection and can be used to purify water and soil from phenol, oil and oil products, metal ions (copper, zinc, etc.).

Currently, there are a large number of methods for producing sorbents for purifying water and soil from phenol, oil and oil products, metal ions.

A known method of producing a sorbent for wastewater treatment simultaneously from suspended solids, petroleum products, colloidal dissolved forms of salts and ions of heavy metals, from organic pollution. The method consists in the fact that the crushed wood obtained from pneumatic wood extracted from the peat deposit is divided into fractions and treated with a solution of mineral acid, followed by laying the processed crushed wood in a filter unit, while the size of the wood fractions increases in the direction of the flow of filtration [patent] RU 2251449, MKP B01J 20/24, 05/10/2005].

The disadvantages of this method are the complex technology for producing the sorbent, the duration of soaking the crushed wood in a solution of mineral acid, a low degree of sorption of oil products.

A known method of producing a sorbent for cleaning the surface of water and soil from oil and oil products, including mechanical grinding of partially dehydrated sludge-osprey - waste pulp and paper production, aerial drying at 120-140 ° C and additional heat treatment of the obtained fiber at a temperature of 174-178 ° C within 60-100 min [patent RU 2279309, MCP B01J 20/24, 07/10/2006].

The disadvantages of this method are the high heat treatment temperatures and the duration of the process.

A known method of producing a sorbent for collecting oil and oil products from water and solid surfaces during the alkaline treatment of hydrolytic lignin, solid particles of impurities are separated, the suspension is subjected to grinding and filtration to obtain a precipitate with a moisture content of not more than 70%, granulating it, drying the granules to moisture no more than 8% and their grinding to obtain the target product [patent RU 2277437, MKP B01J 20/24, 06/10/2006].

The disadvantages of this method are the multi-stage process, the use of aggressive alkaline environments, requiring the use of expensive corrosion-resistant equipment, as well as the toxicity of the lignin used.

A known method of producing a sorbent from husks of buckwheat to remove oil and oil products from liquid media, carried out at a temperature of 460-700 ° C in a drum, shaft or chamber furnaces at atmospheric pressure; in a plasma of a high-frequency discharge of low pressure, in a plasma of a high-frequency or arc discharge of atmospheric pressure [patent RU 2259874, MCP B01J 20/24, 09/10/2005]. Also, a method is known for producing a sorbent for cleaning water bodies and industrial wastes from various chemical contaminants, in particular oil and oil products, by utilizing rice husk, including obtaining a sorbent from a fraction of rice husk up to 3 mm, its heat treatment by pyrolysis at a temperature of 350-500 ° C for 10 to 30 minutes. The remaining volume of rice husks with a fraction of more than 3 mm is used to obtain highly pure silicon dioxide. In the heat treatment process, a reactor is used, which is purged with gaseous pyrolysis products sucked from it. Gaseous pyrolysis products are cleaned of soot. In addition, at least a portion of the rice husk fraction above 3 mm is subjected to grinding [patent RU 2304559, MCP СВВ 33/12, 07/10/2006].

The disadvantages of these methods are the complexity of the sorbent production process, high heat treatment temperatures, significant energy costs, low sorption capacities for copper and cadmium.

A known method of producing a sorbent for cleaning aqueous solutions from contaminants based on a natural polymer in the form of a nutshell, including grinding them to particles up to 10 mm in size, treating with an aqueous solution a mixture of concentrated acetic and nitric acids in a ratio of 9.5-10: 1 for 1 , 5-2.0 hours in a boiling water bath, separation of the solid residue, washing and drying in stages at temperatures of 60-65, 100-105 and 125-130 ° C, grinding to particles up to 3 mm in size [patent RU 2302896, INC B01J 20/24, 07.20.2007].

The disadvantages of this method are the duration of the processes of obtaining and drying, the use of high concentrations of acids.

A known method of producing a sorbent based on manganese oxides for the extraction of metals from solutions, in particular strontium, comprising mixing a solution of alkali metal permanganate with a reducing agent in an alkaline medium to obtain a suspension of a precipitate of manganese oxides, aging the suspension, introducing an organic binder in the amount of 0 during the suspension, 5-10% of the mass of the formed precipitate of manganese oxides, separation of the precipitate, its drying on the working surface, calcination, decription and isolation of granules. As an organic binder, substances selected from the group are used: polyvinyl alcohol, polyacrylamide, polyvinyl acetate, carboxymethyl cellulose, gelatin, casein [patent RU 2263536, MKP B01J 20/06, 10.11.2005].

The disadvantages of this method are the complexity of the technology, poor reproducibility of the sorption-selective properties of sorbents of different batches, the inability to use this sorbent for sorption of polar and non-polar compounds.

A known method of synthesizing a sorbent for cleaning solutions and wastewater of cesium radionuclides by reacting a transition metal salt with ferrocyanide ions on the surface of bentonite particles in an environment of wine material / wine, juices / at pH 2-4 in the presence of gelatin, fish glue. The obtained composite sorbent KhZh-90 contains 1-10 wt.% Transition metal ferrocyanide. The basis for the sorbent is waste from the demetallization and clarification of wine materials [patent RU 2007211, MCP B01J 20/02, 02.15.1994].

The disadvantages of this method are the complexity of the technology for producing the sorbent and the narrow profile of its use - only for sorption of cesium radionucleides.

The closest is a method of producing a sorbent for purification of water from heavy metals, polar organic substances (dyes, phenol, etc.) based on natural aluminosilicate (zeolite, expanded vermiculite or a mixture thereof) modified with chitosan, treatment of aluminosilicate with a solution of chitosan in diluted acetic acid with the mass ratio of aluminosilicate to a solution of chitosan, equal to 1: 1, and the final pH of the solution over the precipitate, equal to 8-9. The formed plastic mass is granulated by extrusion through dies of a given size, the obtained granules are dried, then treated with a solution of humic acids taken in an amount that ensures complete binding of the chitosan amino groups, the sorbent granules are separated from the solution and the polymer layer is cured on the surface of the granules [patent RU 2277013, MKP B01J 20/16, 05.27.2006].

The disadvantages of this method are the low degree of sorption of metal ions, the inability to use a sorbent to collect oil and oil products, its extremely low biodegradability, which does not meet environmental safety.

The objective of the proposed technical solution is to develop a technologically advanced method for producing a sorbent based on a polymer-colloidal complex of chitosan-gelatin, which can be used for sorption of metal ions (copper, zinc, etc.), for collection as polar organic substances (phenol, etc.) and non-polar organic compounds - oil and oil products from the surface of water and soil. This reduces the consumption of chitosan used to obtain the sorbent, which leads to a decrease in the cost of the product and improve the sorption characteristics of the sorbent.

The technical result is to increase the sorption characteristics of the sorbent in relation to metal ions and the possibility of using the proposed sorbent for the purification of water and soil from phenol, oil and oil products. Moreover, the sorbent is non-toxic, biodegradable and environmentally friendly.

The technical result is achieved in a method for producing a sorbent for water purification based on a natural polymer, and the water is treated with a polymer-colloidal complex obtained by mixing a solution of chitosan in dilute acetic acid with 5-10% aqueous gelatin solution in a mass ratio of 1: (1 , 8-2,2) followed by filtration and drying.

Gelatin and chitosan are good complexing agents with ions of various metals; upon the formation of the gelatin-chitosan polymer-colloidal complex, centers of ion-coordination interactions are formed between the positively charged protonated amino groups of chitosan ~ NH ³⁺ and the carboxyl anion - amino acid residues of the protein ~ СОО ^- ; due to these centers and binding occurs with metal ions.

The polymer-colloidal complex has both a hydrophilic and branched structure, contains a sufficient number of functional amino groups capable of complexation with phenol, oil and oil products.

The claimed mass ratio of chitosan and gelatin 1: (1.8-2.2) to obtain a sorbent is optimal, since in this ratio an equivalent ratio of reactive groups of chitosan and gelatin is observed, which leads to the formation of a polymer-colloidal complex with the best sorption characteristics. When using gelatin less than 1.8, the degree of extraction of oil and oil products decreases, and above 2.2 the solubility of the complex in water increases, gelatin begins to leach.

The use of a 5-10% aqueous solution of gelatin favorably affects the formation of a polymer-colloidal complex with chitosan. At a gelatin concentration in an aqueous solution of less than 5%, the complex is obtained in a very dilute form, which increases the cost of extracting contaminants, and at a concentration of more than 10%, a very high viscosity of the reaction mixture is obtained, it becomes difficult to obtain a homogeneous homogeneous product, and the power consumption of the mixer increases.

The method of obtaining the sorbent is as follows.

A weighed portion of chitosan weighing 2 g is dissolved in an aqueous solution of acetic acid, stirred and left to swell for 30 minutes at a temperature of 20-25 ° C.

A portion of gelatin weighing 5-10 g is dissolved in 95-90 ml of water, respectively, and left to swell for 20-30 minutes at a temperature of 20-25 ° C. Next, the swollen gelatin is brought to complete dissolution in a water bath with stirring at a temperature of 55-60 ° C.

To form a polymer-colloidal complex, the resulting solutions are thoroughly mixed on a magnetic stirrer for 20-30 minutes at a temperature of 20-25 ° C, filtered and dried under vacuum to constant weight.

As a result, a dehydrated polymer-colloidal chitosan-gelatin complex is obtained, which, depending on the requirements, is subsequently either formed or crushed and used as a sorbent for purifying water and soil from phenol, oil and oil products, metal ions.

Example 1. In 100 ml of a 2% solution of chitosan in an aqueous solution of acetic acid, 80 ml of a 5% aqueous solution of gelatin (ratio 1: 2.0) is introduced at a temperature of 20-25 ° C and stirred for 20-30 minutes on a magnetic stirrer until complete distribution of the volume of the reaction mixture. The mixture is then filtered and dried under vacuum to constant weight.

Example 2. In 100 ml of a 2.5% solution of chitosan in an aqueous solution of acetic acid, 70 ml of a 7% aqueous solution of gelatin (ratio 1: 2.2) is introduced at a temperature of 20-25 ° C and stirred for 20-30 minutes on magnetic stirrer until complete distribution of the volume of the reaction mixture. The mixture is then filtered and dried under vacuum to constant weight.

Example 3. In 100 ml of a 3% solution of chitosan in an aqueous solution of acetic acid, 55 ml of a 10% aqueous solution of gelatin (ratio 1: 1.8) is introduced at a temperature of 20-25 ° C and stirred for 20-30 minutes on a magnetic stirrer until complete distribution of the volume of the reaction mixture. The mixture is then filtered and dried under vacuum to constant weight.

Table 1 shows the comparative characteristics of the sorbent obtained in examples 1-3, and the sorbent from the prototype. It has been experimentally shown that the obtained sorbent based on the polymer-colloidal complex chitosan-gelatin has high sorption characteristics not only for various metal ions, but also for phenol and oil products.

Table 1 Comparative characteristics of sorbents No. p / p Characteristics of the sorbent Polymer-colloidal complex chitosan-gelatin A mixture of vermiculite with chitosan (prototype) one Bulk specific gravity, g / cm ³ 1.10 0.7-0.75 2 Oil capacity, cm ³ / cm ³ 4,5 - 3 Static exchange capacity, mg / g for Cu ^{2+ ions} 6.0 5.85 by ions of Fe ³⁺ 7.1 6.90 by ions of Zn ²⁺ 5.1 - by ions Cd ²⁺ 5.7 - by ions of Ni ²⁺ 4.2 -

Bulk specific gravity was determined by the gravimetric method according to the method described in the book "Production of products from polymeric materials: Textbook. V.K. Kryzhanovsky, M. L. Kerber, V. V. Burlov, A. D. Panimatchenko. - St. Petersburg. : Profession, 2004. - 464 p. "

Oil intensity was determined by the degree of swelling of the sorbent in a solution with phenol and oil products according to the method described in the book [Workshop on the chemistry and physics of polymers: Textbook. ed. "Under the editorship of V.F. Kurenkov. - M.: Chemistry, 1990. - 304 p."

The static exchange capacity of the polymer-colloidal complex of chitosan-gelatin by metal ions was determined according to GOST 20255.1-89. Method for determining the static exchange capacity. Publishing house of standards. 1989 .-- 112 p.

Example 4. To determine the degree of purification of wastewater from oil products, 500 ml of oil-containing wastewater is poured into the column and a sorbent based on a polymer-colloidal complex of chitosan-gelatin weighing 2 g is passed through it, after which the solution is filtered and the degree of purification of water from contaminants on the analyzer Fluorat-02 fluid [Method for measuring the mass concentration of phenol and oil products in wastewater samples using the Fluorat-02 fluid analyzer TU 4321-001-20506233-94]. Phenol containing wastewater is treated in a similar manner. As a result, the degree of water purification from oil products is 98.5%, from phenol - 96.8%.

Thus, the use of a sorbent based on the polymer-colloidal complex chitosan-gelatin allows one to increase its sorption characteristics in relation to various metal ions, and to purify water and soil from phenol, oil, and oil products. This seems promising, since the resulting sorbent is non-toxic, biodegradable, environmentally friendly. The manufacturing process is very simple, does not require expensive chemical equipment and large energy costs.

Claims (1)

A method of producing a sorbent for water purification, comprising the interaction of chitosan in a solution of diluted acetic acid with a reagent capable of forming a polymer-colloidal complex, characterized in that a solution of chitosan in diluted acetic acid and a 5-10% aqueous gelatin solution are fed to the interaction the mass ratio of chitosan to gelatin equal to 1: (1.8-2.2).