RU2321600C2 - Cross-linked copolymers of 1-vinyl-1,2,4-triazole with divinyl sulfide as sorbents of precious metals and method for their preparing - Google Patents

Abstract

FIELD: chemistry of high-molecular compounds, chemical technology.

SUBSTANCE: invention relates to novel nitrogen- and sulfur-containing cross-linked copolymers of 1-vinyl-1,2,4-triazole with divinyl sulfide that can be used for extraction of gold, silver and platinum from acid solutions. Invention relates to a method for synthesis of cross-linked copolymer of 1-vinyl-1,2,4-triazole with divinyl sulfide for a single step and without using a solvent. Method involves the copolymerization reaction of divinyl sulfide being both as a second monomer and as a cross-linking agent. Synthesized copolymers show high chemical stability, multiple using in cycles sorption-desorption, effective chelating capacity and high values of sorption capacity with respect to ions of precious metals, possibility for extraction of precious metals from complex solution and high values of the partition coefficients that allows their using for extraction of low concentrations of precious metals. Above indicated copolymer comprising triazole cycles is synthesized by the copolymerization reaction of 1-vinyl-1,2,4-triazole and divinyl sulfide without solvent under condition of radical initiating with azobis-isobutyric acid dinitrile (2% of monomers mixture mass) at temperature 60°C for 0.25-2 h, in argon atmosphere followed by washing out copolymer with ethyl alcohol. Synthesized copolymer has the general formula given in the invention description wherein n = 35-81 mole%; m = k = 19-65 mole%.

EFFECT: improved method of synthesis.

3 cl, 5 tbl, 9 ex

Description

The invention relates to the field of macromolecular compounds, in particular to new nitrogen- and sulfur-containing network copolymers of 1-vinyl-1,2,4-triazole with divinyl sulfide, which can be used to extract gold, silver and platinum from acidic solutions.

A well-known sorbent based on aminopolystyrene of linear structure, where polystyrene-azorodanine acts as complexing groups, for the selective concentration of noble metals: gold and platinum (NN Basargin, Yu.G. Rozovsky, V.N. Zharova and others. Organic reagents and chelating sorbents in the analysis of mineral objects. M: Nauka, 1980. P.82-116). A complex-forming sorbent is known that contains 2-mercaptobenzthiazole groups (POLIORGS XII) for the selective concentration of gold and silver (N.I. Shcherbinina, G.V. Myasoedov, G.A. Khabadov et al. Journal of Analytical Chemistry, 1990. T. 45. Issue 11. S.2137-2144).

Closest to the claimed invention is a method for producing copolymers containing in their structure 1-vinylbenzimidazole and acrylonitrile, which can be used in the sorption of gold from acidic solutions (A.I. Skushnikova, L.P. Shaulina, E.S. Domnina, M .P. Zverev, A.N. Barash, E.D. Soloviev, G.S.Kholodnaya, N.F. Kalyanova, I.P. Golentovskaya, E.Tundeviyn Auth. SU 1735310 A1, 23.05. 1992 ) These copolymers are prepared by copolymerization of 1-vinylbenzimidazole with acrylonitrile in the presence of ammonium persulfate in dimethyl sulfoxide.

The fundamental difference of the present invention is that for the first time new complex-forming polymer sorbents from the class of heterocyclic compounds have been developed, which include copolymers containing vinyl triazole rings in their structure, as well as a divinyl sulfide fragment, which is simultaneously a comonomer and a crosslinking agent due to the presence of two vinyl groups .

Copolymers based on 1-vinyl-1,2,4-triazole and divinyl sulfide have not been known to date.

This goal is achieved by developing a method for producing new network copolymers based on 1-vinyl-1,2,4-triazole and divinyl sulfide with a ratio of the starting components (30-97) :( 70-3) (mol.%), Respectively, and using them in as sorbents of gold, silver, platinum. The proposed mesh copolymers allow the extraction of noble metals in a wide range of medium acidity (1-7 M) with a distribution coefficient of the order of 10 ³ -10 ⁴ cm ³ / g depending on the structure of the copolymers.

Mesh copolymers containing triazole rings in the macrochain were synthesized by radical copolymerization of 1-vinyl-1,2,4-triazole with divinyl sulfide in the presence of azobisisobutyric acid dinitrile (2 wt.%) In the mass of comonomers at 60 ° C for 0.25-2 h, their structure can be represented by the general formula

where n = 81-35 mol.%; m + k = 19-65 mol%.

The synthesized copolymers are a non-melting glassy mass of light yellow color, the polymers are insoluble in water and in organic solvents, but swell in water up to 100%.

The network structure of the obtained copolymers was established according to the data of IR spectroscopy, elemental analysis, and is also confirmed by a complete loss of solubility, which is typical for polymers of precisely the network structure [E.B. Trostyanskaya, P.G. Babaevsky. The formation of cross-linked polymers // Advances in Chemistry. 1971.V.40. Issue 1. S.115-141]. Since the copolymers are a glassy mass, they can be attributed to densely cross-linked network polymers in which the crosslinking units (branching units) are formed by transverse chemical bonds due to the involvement of the second double bond of the divinyl sulfide molecule in the copolymerization reaction. Thus, divinyl sulfide is both a comonomer and a crosslinking agent. According to the IR spectra, the thiovinyl group (residual double bonds) in the structure of the copolymers synthesized by us is present in trace amounts, as reflected in the above formula.

The proposed mesh copolymers containing heteroatoms of nitrogen and sulfur in the macromolecules are used for sorption extraction of gold, silver, platinum and have the following advantages:

- the simplicity of the method for producing cross-linked copolymers (in one step, without the use of a solvent);

- divinyl sulfide acts in the copolymerization reaction simultaneously as a second comonomer and as a crosslinking agent;

- high chemical resistance of the copolymers, the possibility of multiple (4-5 cycles) of their use in the sorption - desorption cycles;

- effective complexing ability and high sorption capacities with respect to noble metal ions;

- the ability to extract precious metals from complex compositions of solutions containing 10 ^3- fold excess of ions of iron, nickel, cobalt, zinc and lead;

- high distribution coefficients, which allows us to recommend sorbents for the extraction of low concentrations of precious metals.

The following non-limiting examples illustrate the invention.

Synthesis of copolymers of 1-vinyl-1,2,4-triazole with divinyl sulfide.

Example 1

3.89 g (41 mmol) of 1-vinyl-1,2.4-triazole, 0.11 g (1.3 mmol) of divinyl sulfide, 0.08 g (0.5 mmol) of azobisisobutyric acid dinitrile were placed in a glass ampoule. The reaction mixture was kept in a mass of comonomers in an argon atmosphere at a temperature of 60 ° С for 0.25 h. After synthesis, the copolymer (I) was washed with ethanol in a Soxhlet apparatus and dried in vacuum to constant weight. The copolymer yield is 2.52 g (63%). The copolymer is a light yellow glassy mass, which is ground into a powder, insoluble in organic solvents. The copolymer I contains in the macromolecule 1-vinyl-1,2,4-triazole 81 mol.%, Divinyl sulfide 19 mol.% (For the ratio of monomers in the initial mixture 97: 3 mol.%), Which is confirmed by the data of elemental analysis (found, wt. .%: N 35.83; S 2.81).

Example 2. Under conditions similar to those described in example 1, but with a ratio of the starting components in the mixture of 3.6 g (37 mmol) of 1-vinyl-1,2,4-triazole, 1.4 g (16 mmol) of divinyl sulfide, 0.1 g (0.5 mmol ) of azobisisobutyric acid dinitrile and a reaction time of 2.5 hours, a copolymer (II) was obtained. The resulting copolymer in the form of a yellowish glassy block was washed with ethanol in a Soxhlet apparatus and dried in vacuum to constant weight. The copolymer yield is 3.55 g (71%). The synthesized copolymer II contains 1-vinyl-1,2,4-triazole 54 mol. %, divinyl sulfide 46 mol.% (for the ratio of monomers in the initial mixture 70:30 mol.%), which is confirmed by the data of elemental analysis (found, wt.%: N 25.01; S 10.97).

Example 3. Under conditions similar to those described in example 1, but with a ratio of the starting components in the mixture of 2.1 g (22 mmol) of 1-vinyl-1,2,4-triazole, 1.9 g (21 mmol) of divinyl sulfide, 0.08 g (0.49 mmol ) dinitrile of azobisisobutyric acid and a reaction time of 3 hours, copolymer (III) was obtained. The resulting copolymer in the form of a yellowish glassy block was washed with ethanol in a Soxhlet apparatus and dried in vacuum to constant weight. The yield of copolymer 2.91 g (73%). The synthesized copolymer III contains 1-vinyl-1,2,4-triazole 35 mol.%, Divinyl sulfide 65 mol.% (For the ratio of monomers in the initial mixture 50:50 mol.%), Which is confirmed by the data of elemental analysis (found, wt. %: N 16.39; S 19.37).

In the IR spectra of copolymers I, II, and III, there is no absorption band at 1654 cm ^–1 , corresponding to stretching vibrations of the double bond of the vinyl group in 1-vinyl-1,2,4-triazole, but the absorption bands of bending and stretching vibrations of the triazole ring at 650, 880, 1120, 1430, 1500 cm ^-1 . The absorption band of the thiovinyl groups (CH ₂ = CH) ₂ S of divinyl sulfide does not completely disappear, a weak absorption peak remains at 1585 cm ^-1 , which corresponds to stretching vibrations of the double bonds of the residual thio vinyl group. The absorption band at 660 cm ⁻¹ refers to stretching vibrations of the CSC bond.

Example 4. The extraction of gold depending on the concentration of acids.

A portion of the copolymer of 10 mg (when using copolymer II) under static conditions at room temperature was contacted with 20 ml of a solution containing 2 mg of gold in various concentrations of hydrochloric or sulfuric acids. Sorption was carried out with vigorous stirring for 1 h. The copolymer was filtered on a white ribbon paper filter. In the filtrate, the residual gold concentration was determined by the atomic absorption method and the percentage recovery was calculated (Table 1).

Example 5. Extraction of silver depending on the concentration of acids.

A weighed portion of the 10 mg copolymer (using copolymer II) in static mode was contacted for 20 min with 20 ml of a solution of nitric or sulfuric acids of various concentrations containing 2 mg of silver. The copolymer was separated from the solution by filtration through a white ribbon filter. In the filtrate, the residual silver concentration was determined by the atomic absorption method and percent recovery was calculated (Table 1).

Example 6. The recovery of platinum depending on the concentration of acids.

A portion of the copolymer of 10 mg (using copolymer II) under static conditions at room temperature was contacted with 20 ml of a solution containing 4 mg of platinum in hydrochloric or sulfuric acids of various concentrations. Sorption was carried out with vigorous stirring for 1 h. The copolymer was filtered on a white ribbon paper filter. In the filtrate, the residual platinum concentration was determined by the photometric method according to the reaction of the formation of platinum-tin complexes and the percentage recovery was calculated (Table 1).

Example 7. The effect of the phase contact time on the extraction of metal from 1 M acid solutions.

A portion of the copolymer of 10 mg (using copolymer I) was contacted with a certain amount of metal with stirring for the required period of time. The copolymer was separated by filtration, the residual metal concentration in the solution was determined, and percent recovery was calculated. The dependence of metal recovery on the phase contact time is presented in Table 2. The extraction is characterized by high speed, the time to establish equilibrium is 15-20 minutes for gold and silver and 60 minutes for platinum; when using a larger sample, complete metal recovery can be achieved.

Example 8. The dependence of the extraction of metals from their concentration in solution.

10 mg of the copolymer was contacted in static mode for 60 min with 1 M acid solutions containing various amounts of metals. The solid phase was separated from the solutions by filtration, the residual concentrations of metals were determined in the solutions, and their content in the solid phase was calculated. The results obtained are presented in table.3.

The static sorption capacity of the copolymer was calculated by the ratio of metal recovery by the copolymer (mg) to the mass of the copolymer (g). The values of the static sorption capacity for copolymers relative to noble metals are given in table 4.

Copolymer I has a high sorption capacity for silver (in H ₂ SO ₄ sorption is 1187 mg / g); for gold - copolymers II and III (in HCl, sorption is 1100-1170 mg / g, in H ₂ SO ₄ 1560 mg / g); for platinum - copolymer III (sorption in HCl is 940 mg / g, in H ₂ SO ₄ 810 mg / g).

Example 9. The study of the possibility of regeneration of copolymers.

A portion of a copolymer of 10 mg was contacted in a 1 M solution of sulfuric acid with 0.1 mg of gold (silver). The solution was separated from the precipitate and the concentrate was treated with 10 ml of thiourea at temperatures of 24 and 70 ° C. After a certain period of time, the thiourea solution was filtered off and the gold (silver) content was determined (Table 5).

Almost complete extraction of gold and silver from the phase of copolymer II with a 1 M solution of thiourea in 1 M H ₂ SO _{4 was} observed at 70 ° C for one hour.

Table 1 Extraction of noble metals by copolymer depending on acid concentration The concentration of acids, mol / l Extraction of precious metals,% Silver Gold Platinum HNO ₃ H ₂ SO ₄ Hcl H ₂ SO ₄ Hcl H ₂ SO ₄ 1.0 94.2 95.2 82.0 96.0 70.0 61.0 2.0 92.1 95.1 81.5 96.0 68.9 58.5 3.0 92.0 94.8 81.0 95.5 67.0 50.0 4.0 92.0 93.0 80.8 94.0 64.9 46.2 5.0 92.0 93.0 80.0 91.2 60.0 38.5 6.0 92.0 93.0 79.0 89.5 59.1 29.8 Note: solution volume = 20 ml, _nozzle mass = 10 mg, _nozzle time = 2 hours; mass _Ag = 2 mg; mass _Au = 2 mg; mass _Pt = 4 mg.

table 2 The dependence of the extraction of precious metals from the contact time of the phases
copolymer Sorption time, min Recovery% Gold, (1 M HCl) Silver, (1M HNO ₃ ) Platinum, (1 M HCl) 10 77 59 35 thirty 79 73 fifty 60 82 75 67 120 82 75 70 Note: solution volume = 20 ml, mass _Ag = 2 mg; mass _Au = 2 mg; mass _Pt = 4 mg.

Table 3 The dependence of the extraction of precious metals on their concentration in solution (solution volume 20 ml) The amount of metal in the initial solution, mg Found metal in the copolymer, mg / g Sorption from 1 M HCl Sorption of 1 MH ₂ SO ₄ Gold 0.66 61 61 1.32 127 128 5.29 513 462 10.58 990 933 15.87 1038 1302 21.16 1150 1590 32.00 1175 1530 Platinum 1.00 131 86 2.00 404 259 6.24 480 486 12.49 515 474 18.74 624 536 21.86 680 573 24.98 920 822 31.22 950 815 Silver 1 M HNO ₃ 1 MH ₂ SO ₄ 0.50 88 44 1.00 170 91 4.00 265 178 6.00 340 282 11.00 - 395 12.00 487 490 13.00 500 527 5 p.m. 540 -

Table 4 Static tanks of copolymers in 1 M acid solutions Metal Acid Static tanks, mg / g Copolymer I Copolymer II Copolymer III Silver HNO ₃ 325 180 560 H ₂ SO ₄ 1187 325 520 Gold Hcl 860 1100 1170 H ₂ SO ₄ - - 1560 Platinum Hcl 503 - 940 H ₂ SO ₄ 553 - 810

Table 5 The effect of the time factor on the elution of metal ions from a concentrate with a thiourea sulfate solution
mass of nozzles. = 10 mg; mass of _Au , _Ag = 100 μg; V _thiourea = 10 ml T _desorption , ° C τ _desorption , min Desorption,% 24 Silver Gold 5 fifteen 12 10 28 thirty twenty 49 45 thirty 59 55 40 63 58 60 66 62 80 67 63 120 72 82 70 5 16 twenty 10 29th 32 twenty 62 71 thirty 78 82 40 83 85 60 92 88 80 93 90 120 99 99

Claims (3)

1. Net copolymer of 1-vinyl-1,2,4-triazole divinyl sulfide of the General formula

where n = 81-35 mol.%; m + k = 19-65 mol.% as an effective sorbent of gold, silver, platinum from acidic solutions. 2. The method of producing a network copolymer according to claim 1, characterized in that the above copolymer containing triazole rings in its structure is synthesized by copolymerization of 1-vinyl-1,2,4-triazole and divinyl sulfide in bulk, without solvent under conditions of radical initiation with dinitrile azobisisobutyric acid (2% by weight of the mixture of monomers), at 60 ° C, for 0.25-2 hours, in an argon atmosphere, followed by washing the copolymer with ethyl alcohol. 3. The method according to claim 2, characterized in that the network copolymers are obtained using divinyl sulfide, simultaneously as a second comonomer and as a crosslinking agent.