CS270844B1 - Method of metallic iones cu(ii),pb(ii),hg(ii),cd(ii),ni(ii),zn(ii),sr(ii),la(iii),uo2 2+, th(iv) removal from aqueous solutions - Google Patents

Abstract

The method applies to the removal of metallic ions such as Cu(II), Pb(II), Hg(II), Cd(II), Ni(II), Zn(II), Sr(II), La(III), UO2<2+>, Th(IV) from aqueous solutions with the subsequent regeneration of used tenside is that the tensides of type C-alkyl amide of ethylenediaminetetraacetic acid with alkyl C6 to C20 act on the aqueous solutions of metals so that a ratio of tenside and metal is 1:1 to 3 in the extent of pH 1 to 7, while a separable precipitate of the metal complex with tenside arises either directly, or the pH necessary for the creation of precipitate is achieved by adding mineral acids, such as sulphuric acid, nitric acid, hydrochloric acid (hydrogen chloride), and subsequently by adding the foresaid mineral acids in a concentration of 1 to 5 moles x dm<-3> to the isolated precipitate of the complex. Metallic ion is isolated in the form of a soluble inorganic salt under simultaneous precipitation of the original tenside. By the method described, 80 to 99.9 mass % of metal is removed from the aqueous solutions, and by a subsequent regeneration of tenside, 90 to 99 mass % of the original tenside is possible to obtain for repetitive use.

Description

The invention relates to a method for removing metal ions such as Cu (II), Pb (II), Hg (II), Cd (II), Ni (II), Zn (II), Sr (II), La (III), U0. ₂ ²⁺ , Th (IV) from aqueous solutions.

Currently, several methods are used to remove metal ions from aqueous solutions: extraction methods - Morrison G.H., Freiser H .: Extraction Methods in Analytical Chemistry, SNTL, Prague (1962); Calligaro L., Mantovani A., Belluco U., Acampora M., Polyhedron 2, 1189 (1903); Malát M .: Fresenius Z. Anal. Chem. 297, 497 (1979); Pakalns P .: Water Res. 15, 7 (1981); Chakravotty V., Dash K. G., Mohanty S. R., Radiochem. Acta, 40, 89 (1986); Grimm R., Kolarik Z .: Inorg. Nucl. Chem. 36, 189 (1974); Schepper A .: Hydrometallurgy 4, 285 (1979). In classical extraction, the presence of surfactants affects the properties of the interfacial surface, thereby negatively affecting the extraction rate and extraction efficiency. Huttinger K.J., Schegk J.R .: Chem. Ing.Těch. 53, 574 (1981); Ossec - Asare K .: Why. Int. Solv. Extr. Conf. ISEC '83, Denver 278 (1983). When using a surfactant as part of the aqueous phase in extraction, the surfactant interferes with both phases to form emulsions, which negatively affects the whole process - Pakalns P .: Water Res. 15, 7 (1981). the ion flotation process involves the addition of an ionic surfactant to the counterion ions solutions. By bubbling the system through air or nitrogen, the surfactant is adsorbed along with the separated component on the surface of the bubbles and is thus separated from the solution - Berg E.W., Downey D.M .: Anal. Chim. Acta 120,237 (1980); 121, 239 (1980); 123, 1 (1981); Lieam-Fang-Wu, Rui-Chim-Kuo, Shang-0, and Huang: J. Chines. Chem. Soc. 27, 165 (1980). Chelating agents were used to isolate many metals: Kálalová E., Radová Z., Ulbert K., Kálal J., Švec F .: Europ. Polym. 13, 299 (1977); Radová Z., Kálalová E., Kálal J., Kukuškin 3u.N., Simanová S.A., Konovalov L.V., Then V.H .: Angew. Dep. Chem. 81, 55 (1979); Kálalová E .: Chem. Avg. 31, 70 (1981). In many cases, the irreversibility of the sorption process, the use of high-concentration eluting acids or the heating of the colonies to increase the metal desorption effect prevent the economic use of these methods:

I

Kanert, G. A., Chow A., Anal. Chim. Acta 78: 375 (1975). Ion exchange techniques are also used to obtain metals: Brajter K., Slonawska K .: Talanta 27, 745 (1980); Korkisch J .: Analytical techniques in environmental chemistry, Pergamon Press, 449 (1981). In multi-stage separation, the ion exchange process is combined with other preconcentration techniques such as evaporation or extraction.

The above deficiencies are eliminated by the removal of metal ions such as Cu (II), Pb (II), Hg (II), Cd (II), Ni (II), Zn (II), Sr (II), La (III). ), U0 ^{2 +} _2, Th (IV) from an aqueous solution, followed by regeneration of the used surfactant, which is characterized in that the aqueous solution containing metal ions is treated with the surfactants of C-alkylamides of ethylenediaminetetraacetic acid with C ^ alkyl and C ₂ q in a molar a surfactant-to-metal ratio of 1: 1 to 3 in the pH range of 1 to 7 to form a separable precipitate of the metal-surfactant complex to which up to 5 mol.dm of mineral acid such as sulfuric acid, nitric acid, hydrochloric acid is added; The ion is isolated as a soluble inorganic salt and the surfactant is collected as a precipitate. The pH of the aqueous metal solution can be adjusted by the addition of a mineral acid such as sulfuric, nitric or hydrochloric acid.

The process according to the invention is demonstrated by examples.

Example 1

To water containing 3.75 * 10 mol / cm @ 2 Cu (II), 2.5 * 10 mol / cm @ 2 of the sodium salt of the surfactant ethylenediaminetetraacetic acid are added. In the thus prepared solution at pH 6.4, a precipitate of the metal-surfactant complex is formed directly, which is separated in a sedimentation tank. The period of sedimentation is 5 to 30 minutes. After separation of the precipitate, the Cu (II) in water is reduced to 98 wt .. 4 from the precipitate can be isolated by addition of sulfuric acid c / H ₂ S0 ₄ / = mol.dm regenerated by 99 weight, of the original surfactant to be collected as a precipitate from the metal salt obtained simultaneously and can be reused for further metal ion precipitation process. .

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Example 2

Water contaminated with 2.5. An equivalent amount of ethylenediaminetetraacetic acid sodium dodecylamide surfactant is added equivalently to ⁵ mol.dm ^{5 of} Cd (II). Upon acidification with HNO 2 to pH 2.7, a filterable precipitate of a metal-surfactant complex is formed. The sedimentation time of the precipitate is 5 to 15 minutes. After separation of the precipitate (filtration, respectively. Centrifugation) metal content of the water-·· is reduced by 80-91% by weight .. The obtained precipitate can be acidified by the addition of HC1 at 5 mol.dm ^"5, wherein the surfactant is to regenerate 90-98% %, and separated from the solution of the co-obtained inorganic metal salt in the form of a precipitate. The separated surfactant precipitate can be used repeatedly to further the metal ion precipitation process.

Example 3

Water containing 5. 10 ^{4 4} mol.dm ^{5 5} Th (IV) is added 2.0. 10 ^{"4 5} mol.drn dodecylamide sodium EDTA. At pH 2.9 a filterable metal precipitate with a surfactant is formed upon acidification with HNO 3, which settles over 5 to 15 minutes. After separation of the precipitate, the metal content in the water is reduced by 80 to 85% by weight. From the isolated precipitate, 90 to 98% by weight of the original surfactant can be recovered by the addition of sulfuric acid c / H ₂ SO 4 = 3 mol.dm ⁵ . which is separated as a precipitate from the presently obtained metal salt and can be reused for another metal ion precipitation process.

Example 4

Water containing 5. 10 &^lt; ⁴ &gt; mol.m &^lt; ^{5 &gt;} Hg (II) is added enough sodium salt of ethylenediaminetetraacetic acid dodecylamide to a surfactant to metal ratio of 1: 1 to 2. After adjusting the pH of the solution with surfactant. After separation of the precipitate by filtration, the Hg (II) content of the solution is reduced by a maximum of 91% by weight.

Example 5

Water containing 3. 10 ^"5 mol.dm" ⁵ Pb (II) was added equivalent amount of a sodium salt of ethylenediaminetetraacetic acid dodecylamide. Upon acidification with HNO 2, a precipitate of Pb (II) with a surfactant is formed at pH 1.9. After separation of the precipitate by filtration, the Pb (II) content of the solution is reduced by 90% by weight.

Separation of metal ions using C-alkyl chelates of ethylenediaminetetraacetic acid C-alkylamides with simple metal chelate isolation, high interconnection process yield with the possibility of a high degree of regeneration of the original components can be used as a simple and economically advantageous method in decontamination of waste conduits and contaminated surfaces to protect the environment and as a method of recovering metals from industrial waste.

Claims (2)

1. Removal of metal ions Cu (II), Pb (II), Hg (II), Cd (II), Ni (II), Zn (II), Sr (II), La (III), U ₂ ²⁺ , ^from aqueous solutions followed by recovery of the usable surfactant, characterized in that the aqueous solution containing the metal ions is treated with a C 1-6 alkylenediaminetetraacetic acid-type surfactant with a C 1-4 alkyl. _Q2 C in a molar ratio of surfactant: metal = 1: 1 to 3 in the range of pH 1-7 to form a precipitate peelable metal complex with a surfactant, to which is added 1 to 5 mol.dm ⁵ of a mineral acid such as sulfuric acid, nitric acid, hydrochloride wherein the metal ion is isolated as a soluble inorganic salt and the surfactant is collected as a precipitate. 2. The method according to claim 1, wherein the pH is adjusted by the addition of mineral acids such as sulfuric acid, hydrochloric acid, nitric acid.