RU2297270C1 - Method of manufacture of filtering material and filtering material manufactured by this method - Google Patents

Abstract

FIELD: water treatment; production of cation-exchange filters of spatial-globular structure used for complex cleaning of water from cations of heavy metals.

SUBSTANCE: proposed method includes condensation of formaldehyde with sulfo-resorcine followed by hardening; resorcine is added to aqueous solution of formaldehyde and sulfo-resorcine at pH=10-12; mixture thus obtained is kept under conditions ensuring simultaneous pre-condensation of sulfo-resorcine and resorcine with formaldehyde; poly-condensation of preoligomers thus obtained and subsequent hardening are performed in acid medium. Filtering material includes product of condensation of formaldehyde with resorcine in acid medium having spatial globular structure; filtering material contains product of condensation of formaldehyde with sulfo-resorcine and resorcine and additionally it contains functional groups SO₃H characterized on infrared spectrum by absorption of material specimen by bands at minima of 1040 cm^-1 (clearly defined band) and 1190 cm^-1 (slightly pronounced band).

EFFECT: enhanced efficiency of removal of heavy materials from water.

6 cl, 1 dwg, 1 tbl, 4 ex

Description

The invention relates to water treatment and can be used to obtain cation-exchange filters of a spatially globular structure, providing complex water purification, including cations of heavy metals.

The prior art polymers of a spatially globular structure (ASG polymers) with high filtration ability and used for the manufacture of filter elements are known.

PGS-polymer is a highly permeable product, non-melting and insoluble in ordinary solvents, the structure of which is formed by microglobules ranging in size from 25-30 Å to 10-14 microns. PGS material with globules of 3-7 microns in size is used for sorption processes at high transmission rates of solutions. Since the size of the PGS ion exchanger microglobules is 2 orders of magnitude smaller than that of standard granite ion exchangers (5–7 μm versus 0.5–0.7 mm), the volumetric transmission rates of solutions can reach values that are 100 times or more higher than the transmission rates of solutions through a fixed ionite layer conventional granulation (1000-2000 versus 10-15 beats per hour, respectively). Microglobules in PGS ion exchanger form a regular highly permeable structure, which is due to the spontaneous self-regulating mechanism of polymer formation. The average pore size is 3-5 microns, a large unfolded surface (up to 100-150 m ² / g), a narrow range of pore size distribution (usually ± 10%) give these materials high technological properties and allow their use as filter baffles. The structure and properties of PGS ion exchanger are known, for example, from the Encyclopedia of Polymers. M .: Publishing house Soviet Encyclopedia, 1972, p. 652-658. Various modifications of the method for producing ASG material, for example, in accordance with A.S. USSR 1378319 dated 05.23.1985, C 08 J 5/20, C 08 G 8/22), A.S. The USSR 1023788 from 10.24.1980, C 08 J 9/10 and others can significantly expand the range of sizes of its pores and thereby increase the permeability of the sorbent.

In such a system, most of the exchange groups are located on the surface of microglobules; mass transfer is achieved not due to the diffusion of ions from the solution into the interior of the polymer body (as is the case in ordinary ion exchangers, including macroporous ones), but due to the forced leakage of solutions through the micropores of the polymer body. The exchange rate obeys the laws of film kinetics, and therefore the ion exchange on ASO-ion exchangers proceeds the more efficiently, the faster the solution is renewed in micropores, i.e. the exchange rate increases with increasing rate of transmission of the solution.

ASG filtering materials and methods for their preparation are known, in particular, from US Pat. No. 4,567,207, C 08 G 12/00. The patent protects a wide range of materials obtained by polycondensation of formaldehyde with a monomer capable of forming an ASG structure with formaldehyde in an acidic medium at pH 0.1 ... 4. The concentration of the polymer is 20 ... 65 wt.%. The pore diameter of the polymer is 0.0025 ... 10 μm, the permeability coefficient is 2 × 10 ^-7 ... 2 × 10 ^-2 cm / sec.

According to examples 5 and 6 of the known solution for the manufacture of an ASG polymer with a high filtering ability, aqueous solutions of resorcinol and formaldehyde are mixed, hydrochloric acid catalyst is introduced, and it is held for a time sufficient to form 38-40 wt.% Of the polymer. Then the suspension is poured into molds for curing and kept at room T, after which it is heated to T = 80 ... 82 ° C.

Despite the high filtration properties, materials manufactured according to the technology of US Pat. No. 4,567,207 exhibit weak ion-exchange properties in neutral and slightly alkaline environments. In acidic media, ion exchange is practically absent. These features of the behavior of the known material do not allow it to effectively remove heavy metals from aqueous media.

The ASG-polymer known from US 4,567,207, which contains the condensation product of resorcinol and formaldehyde in the presence of acid, is the closest to the claimed solution of the filter material.

The prior art method for producing sulfophenol cation exchangers of high capacity, chemical resistance and mechanical strength (AS USSR 108258, 39b, 22, 12q, 20 ₀₁ ). According to the known solution, sulfophenol cation exchangers are obtained by condensation of monohydric or polyhydric phenols or sulfophenols, first with sulfonic acids of aliphatic or aromatic carbonyl compounds, and then with formaldehyde, in order to increase the number of sulfo groups introduced into the cation exchange resin without increasing the amount of sulfonated carbonyl compound in the first stage of the process, for condensations with phonols or sulfophenols apply aliphatic or aromatic ketone sulfonic acids.

The known method, which is the closest to the claimed method of manufacturing a filter material (prototype), does not provide the ASG polymer with sulfo groups.

The task of the invention is to increase the operational properties of the filter material by purposefully changing its structure, which allows for the removal of heavy metals from water.

The problem is solved due to the fact that in the method of manufacturing the filter material, including the condensation of formaldehyde with sulforesorcinol and curing, the process is as follows:

- sulforesorcinol and resorcinol are added to an aqueous solution of formaldehyde and the mixture is kept at a pH of 10 ... 12 under conditions ensuring the simultaneous occurrence of precondensation of sulforezorcin and resorcinol with formaldehyde;

- polycondensation and curing of the obtained foroligomers is carried out in an acidic environment. This results in the formation of sulforesorcin formaldehyde ASG polymer. Special cases of the implementation of the proposed solutions are characterized by the following parameters:

- polycondensation of foroligomers is carried out at T = 17 ... 33 ° C, for a time of 0.6 ... 2 hours;

- curing is carried out in two stages - first at T = 30 ... 40 ° C for 1-2 hours, and then at T = 85 ... 95 ° C for 16-24 hours.

The resulting filter material containing the condensation product of sulforesorcinol and resorcinol with formaldehyde is characterized by a spatially globular structure, as evidenced by its permeability with respect to water and aqueous solutions. On the IR absorption spectrum of the material sample (drawing), bands with minima of 1040 cm ^-1 (characteristic band) and 1190 cm ^-1 (weakly pronounced band) are clearly distinguishable, corresponding to stretching vibrations of the groups — SO ₃ N. At the same time, IR the absorption spectrum of the ASG material based on resorcinol-formaldehyde polymer such bands are absent (drawing). These features of the infrared absorption spectrum indicate the presence in the claimed material of related functional groups - SO ₃ N.

The essence of the method lies in the fact that the inventive sulfonated strongly acidic cation exchange resin is obtained as a result of three-dimensional polycondensation of sulfonated resorcinol with resorcinol and formaldehyde.

The reaction involves several stages:

1. First, the reactor conducts the reaction of precondensation of resorcinol and sulforesorcinol with formaldehyde in an alkaline environment.

2. After the formation of foroligomers in the same reactor, the reaction of their condensation with formaldehyde in an acidic medium is carried out to obtain oligomers of higher molecular weight.

3. At stage 3 of the synthesis, when the formation of a water-insoluble product begins, the reaction solution (emulsion) is poured into pre-prepared forms, where gelation proceeds, and then (when heated) and the mixture is completely cured to obtain a three-dimensional polymer of a spatially globular structure in the form ready for practical use of cation exchanger. By controlling the synthesis parameters, it is possible to vary the pore diameter of the obtained polymer in the range of 0.1 ... 3 μm.

It should be noted that in order to obtain the product of the ASG structure with the specified properties, it is necessary to change the parameters of the known process in a substantial way, which is not obvious to a person skilled in the art:

- the synthesis reaction is carried out in two stages - first in an alkaline (pH 10 ... 12), and then in an acidic medium (1≤pH≤3), while in the second stage (acid condensation) by adjusting the pH value, products with pore size. The largest porous polymers (average pore size 3 microns) are obtained in the most acidic medium.

- In the particular case of implementation, the ratio of resorcinol / sulforezorcin is advisable at least 3 mol / mol.

- The concentration of resorcinol in the total volume of the reaction mixture is optimal in the range of 18 ... 20 wt.%.

- The reaction temperature at all stages of the synthesis should be kept within strictly specified limits. So, its increase above 50 ° С at the alkaline stage, as well as going beyond 28 ÷ 33 ° С at the stage of formation of insoluble oligomers, leads to the production of extremely low or nonporous polymers (pore size ≪0.1 μm). In the particular case of the implementation of the solution, the stage of synthesis of the sulfonating agent from excess formaldehyde and sodium sulfite is preliminarily carried out according to the reaction

(the optimal ratio of formaldehyde: sulfite is in the range 4.7 ... 4.9 mol / mol)

Then, in the reactor, the synthesis of sulforesorcinol by reaction (2) and its precondensation with resorcinol and formaldehyde in an alkaline medium at T = 17 ... 33 ° C occur simultaneously.

Further, the process is carried out in the usual sequence.

The invention is illustrated by the following examples.

Example 1

The molar ratio of resorcinol / formaldehyde / sulforezorcinol = 1 / 1.17 / 0.33 mol / mol; [resorcinol] = 17.5 wt.%.

In a reactor containing a solution of 135 g of resorcinol (1.23 mol), 90 g of sulforesorcinol (0.4 mol) and 15 g of caustic soda (0.4 mol of NaOH) in 290 ml of water, 108 ml of a 37% formalin solution (1.44 mol of CH ₂ O) and mix until the smell of formaldehyde disappears completely. The temperature of the mixture is maintained in the range of 46 ÷ 31 ° C. The solution is cooled to room temperature and then a solution of hydrochloric acid (34 ml of concentrated hydrochloric acid in 85 ml of water) is poured into it. Then the reaction mixture (pH ≈ 1) is stirred until cloudy at T = 33 ° C (the beginning of the formation of insoluble oligomers), and then poured into a mold from two coaxially arranged polymer pipes with a framework in the middle, where the polymer solidifies for 1 hour at T = 30 ... 40 ° C. After this, the mold with the hardened polymer is placed in the oven for 24 hours at T = 85 ... 90 ° C for the final formation of a three-dimensional ASG structure in the form of a finished product (filter cartridge). The average pore size of the polymer is 3 microns.

Cation exchange resin in the form of such a cartridge, when used in an acidic medium, is capable of absorbing 2.5 g of calcium cations from a solution with [Ca ²⁺ ] _ref = 1400 mg / L at pH 3.5.

Example 2

The molar ratio of resorcinol / formaldehyde / sodium sulfite = 1 / 2.4 / 0.33 mol / mol; [resorcinol] = 18 wt.%.

51 g of sodium sulfite (0.4 mol) are loaded into a 500 ml container containing 138 ml of 37% formalin (1.87 mol of CH ₂ O) and 142 ml of water and stirred until the latter is completely dissolved for 1 hour, while the formaldehyde: sulfite ratio is 4.7 mol / mol.

In a reactor containing a solution of 135 g of resorcinol (1.23 mol) in 150 ml of water, the resulting solution of a sulfonating agent is poured at room temperature and stirred until the formaldehyde smell disappears completely. The temperature of the mixture is maintained in the range of 35 ... 42 ° C. The solution was cooled to room temperature and an acid solution of formalin (82 ml of 37% formalin (1.11 mol of CH ₂ O) and 35 ml of concentrated hydrochloric acid) was poured into it. Then the reaction mixture (pH ≈ 2) is stirred until cloudy at T = 28 ° C (the beginning of the formation of insoluble oligomers), and then poured into a mold from two coaxially arranged polymer pipes with a framework in the middle, where the mixture solidifies for 1 hour at T = 30 ... 40 ° C. After that, the mold with the hardened polymer is placed in the oven for 24 hours at T = 90 ... 95 ° C for the final formation of the polymer of a three-dimensional ASG structure in the form of a finished product (filter cartridge). The average pore size of the polymer is 1 μm.

After conversion to the Na form, cation exchange resin in the form of such a cartridge, when used in neutral or alkaline media, is able to absorb 6.1 g of nickel cations from a solution with [Ni ²⁺ ] _ref = 340 mg / l.

Example 3

The molar ratio of resorcinol / formaldehyde / sodium sulfite = 1 / 1.6 / 0.33 mol / mol; [resorcinol] = 18 wt.%.

In a 500 ml container containing 146 ml of 37% formalin (1.95 mol of CH ₂ O) and 135 ml of water, a sulfonating agent is preliminarily obtained, for which 51 g of sodium sulfite (0.4 mol) is charged and stirred until the latter is completely dissolved for 0.3 hour, while the ratio of formaldehyde: sulfite is 4.9 mol / mol.

Then, in a reactor containing a solution of 135 g of resorcinol (1.23 mol) in 150 ml of water, a solution of a sulfonating agent is poured at room temperature and stirred until the formaldehyde smell disappears completely. The temperature of the mixture is maintained in the range of 35 ... 42 ° C. The solution is cooled to room temperature, and then a solution of phosphoric acid (34 ml of 78% in 56 ml of water) is poured into it. Then the reaction mixture is stirred (pH≈3) until cloudy at T = 33 ° C (the beginning of the formation of insoluble oligomers), and then poured into a mold from two coaxially arranged polymer pipes with a framework in the middle, where the polymer solidifies for 1 hour at T = 30 ... 40 ° C. After that, the mold with the hardened polymer is placed in the oven for 16 hours at T = 85 ... 90 ° C for the final formation of a three-dimensional ASG structure in the form of a finished product (filter cartridge). The average pore size of the polymer is 0.1 ... 0.3 μm. After conversion to the Na form, cation exchange resin in the form of such a cartridge, when used in an alkaline or neutral medium, is able to absorb 6.5 g of iron cations from a solution with [Fe ²⁺ ] _ref = 290 mg / l.

Example 4

The molar ratio of resorcinol / formaldehyde / sodium sulfite = 1 / 1.5 / 0.33 mol / mol; [resorcinol] = 18 wt.%.

In a 500 ml container containing a solution of 51 g of sodium sulfite (0.4 mol) in 142 ml of water, a sulfonating agent is preliminarily obtained by pouring 138 ml of 37% formalin (1.87 mol of CH ₂ O) and stirring for 20 minutes for 0.3 hour the ratio of formaldehyde: sulfite is 4.7 mol / mol.

Then, in a reactor containing a solution of 135 g of resorcinol (1.23 mol) in 150 ml of water, a solution of a sulfonating agent is poured at room temperature and stirred until the formaldehyde smell disappears completely. The temperature of the mixture is maintained in the range of 46 ... 31 ° C. The solution is cooled to room temperature and then a solution of hydrochloric acid (34 ml of concentrated hydrochloric acid in 85 ml of water) is poured into it. Then the reaction mixture (pH ≈ 1) is stirred until cloudy at T = 28 ° C (the beginning of the formation of insoluble oligomers), and then poured into a mold from two coaxially arranged polymer pipes with a framework in the middle, where the polymer solidifies for 1.5 hours at T = 30 ... 40 ° C. After that, the mold with the hardened polymer is placed in the oven for 24 hours at T = 85 ... 90 ° C for the final formation of a three-dimensional ASG structure in the form of a finished product (filter cartridge). The average pore size of the polymer is 3 microns.

Cation exchange resin in the form of such a cartridge, when used in an acidic medium, is capable of absorbing 2.5 g of calcium cations from a solution with [Ca ²⁺ ] _ref = 1400 mg / l at pH = 3.5.

The synthesis conditions in examples 5 ÷ 7 (with the exception of the parameters listed in the table) are similar to example 4.

Table Example No. The ratio of resorcinol / formaldehyde / sulfonating agent The time to obtain sulfonating agent, min Cure time The average pore size, microns The amount of sorbed Ca ²⁺ , g At +30 ... + 40 ° С When temperature controlled Etc. 5 1 / 1.5 / 0.33 60 2 eighteen 3 2.8 Etc. 6 1 / 1.5 / 0.33 thirty one eighteen 3 2.5 Etc. 7 1 / 1.5 / 0.33 twenty 2 16 3 2.5

To implement the complex invention, which includes two objects - the method and material connected by a single inventive concept, according to the examples disclosed above, the following reagents were used:

Resorcinol brand "Mitsubishi";

Formalin 37% GOST 1625-98;

Sodium sulfite GOST 246-41;

Hydrochloric acid GOST 3118-77;

Phosphoric acid GOST 6552-80.

Claims (6)

1. A method of manufacturing a filter material, including condensation of formaldehyde with sulforesorcinol and curing, characterized in that resorcinol is added to an aqueous solution of formaldehyde and sulforesorcinol at pH = 10-12, the resulting mixture is kept under conditions ensuring the simultaneous course of the condensation of sulforesorcinol and resorcinol with formaldehyde, and the polycondensation of the obtained foroligomers and subsequent curing is carried out in an acidic environment. 2. The method according to claim 1, characterized in that the polycondensation of foroligomers is carried out over a period of 0.6-2 hours 3. The method according to claim 1, characterized in that the curing is carried out in two stages - first for 1-2 hours at T = 30-40 ° C, and then for 16-24 hours at T = 85-95 ° C . 4. The method according to claim 1, characterized in that the mixture of excess formaldehyde with sodium or potassium sulfite is pre-conditioned under conditions that ensure the synthesis of a sulfonating agent in the absence of formaldehyde polymerization, after which resorcinol is added to the resulting solution at pH = 10-12. 5. The method according to claim 4, characterized in that the mixture of excess formaldehyde with sodium or potassium sulfite is kept for 0.3-1 hours at T = 20-30 ° C, while the ratio of formaldehyde: sulfite is 4.7-4, 9 mol / mol. 6. A filter material comprising a condensation product of formaldehyde with resorcinol in an acidic medium having a spatially globular structure, characterized in that the material contains a condensation product of formaldehyde with sulforesorcinol and resorcinol and additionally functional groups — SO ₃ H, characterized on the IR absorption spectrum of the material sample stripes with minima of 1040 cm ^-1 (characteristic band) and 1190 cm ^-1 (mild band).

Images