Sulfide-containing diammonium cationic ionic liquid and preparation method thereof and use thereof in aqueous solution containing Cd 2+ and Pb 2+ Separation method

Abstract

The present invention relates to a diammonium cationic ionic liquid containing thioether and a preparation method thereof and a cation ionic liquid for use in aqueous solution containing Cd 2+ and Pb 2+ A separation method; a diammonium cation ionic liquid containing a thioether, comprising a diammonium cation and a thioether anion; a halide C containing a target cation 19 H 44 N2Br2 and a thioether-containing acid are stirred for reaction, and anhydrous methanol is selected as the reaction atmosphere. The halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with the thioether-containing compound dissolved or dispersed in anhydrous methanol; the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain an ionic liquid. The thioether-containing diammonium cation ionic liquid of the present invention is used to extract Cd from an aqueous solution. 2+ and Pb 2+ Ions; Ionic liquids to Cd 2+ and Pb 2+ The highest extraction efficiencies reached 94.84% and 99.77% respectively, realizing the recycling of ionic liquids.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy metal separation and purification, and more specifically, relates to a diammonium cationic ionic liquid containing thioether and a preparation method thereof and a method for extracting Cd from an aqueous solution. 2+ and Pb 2+ Methods for separation of ions. Background Art

[0002] With the rapid development of modern industrialization, the large-scale mining, smelting, processing and utilization of ferrous and non-ferrous metal ores have led to an increasing amount of wastewater containing heavy metal elements, which seriously threatens the ecological environment and the health of animals and plants. There are many types of heavy metal ions commonly found in wastewater, such as cadmium, lead, copper, cobalt, iron, manganese, molybdenum and zinc, among which cadmium and lead are particularly harmful and are the two heavy metal ions with the lowest water supply and wastewater discharge limits in countries around the world.

[0003] Common methods for removing heavy metal ions from wastewater include chemical precipitation, coagulation, membrane separation, ion exchange, electrolysis and extraction. Chemical precipitation, coagulation, membrane separation, ion exchange and electrolysis are not ideal for treating wastewater containing heavy metal ions, and may also generate intermediate pollutants. The extraction method has the advantages of high separation efficiency, low consumption of extractants, high recovery rate, large production capacity, simple equipment, easy automation and continuity, but it has the disadvantage that heavy metal ions are not easy to separate from the extractants.

[0004] Based on the problems existing in traditional heavy metal ion extraction technology, researchers try to find a new reversible extractant with excellent performance to achieve the extraction of Cd from wastewater. 2+ and Pb 2+ Efficient extraction and recovery of heavy metal ions such as Cd and d-Cd. Ionic liquids have the characteristics of low vapor pressure, good thermal and chemical stability, and easy to control functions. They have broad application prospects in heavy metal wastewater treatment and extraction and recovery of heavy metal elements. They are a new type of green environmental purification material. Ionic liquids can be divided into monocationic and dicationic ionic liquids according to the number of cations and anions they contain. Most of the reported research work focuses on monocationic ionic liquids (ILs), which are very effective for the extraction and recovery of high concentrations of Cd. 2+ and Pb 2+ The extraction effect is good, but it is not suitable for low concentration Cd 2+ and Pb 2+The extraction effect is poor. In the process of treating wastewater, heavy metal ions must be enriched first, and then separated by ionic liquid extraction, which is a complicated and cumbersome process. Dicationic ionic liquids (DILs) have the advantages of more flexible functional adjustment, good thermal stability, larger extraction capacity and faster extraction speed. These characteristics make it more advantageous in application than monocationic ionic liquids. However, the dicationic ionic liquids reported in the literature generally have the problem of difficulty in separating the extractant and heavy metals during the extraction process, and the extraction efficiency needs to be further improved. Therefore, it is necessary to fully design the ionic liquid to develop a method that can maintain low concentration Cd 2+ and Pb 2+ A novel dicationic ionic liquid having both physical and quasi-chemical absorption effects, which has a high absorption capacity and is convenient for subsequent separation and recovery from heavy metal ions. Summary of the invention

[0005] The purpose of the present invention is to overcome the existing ionic liquids to low concentration Cd 2+ and Pb 2+ The disadvantages of low extraction capacity and slow extraction speed are that the extractant and Cd 2+ , Pb 2+ The invention provides a novel diammonium cationic ionic liquid containing thioether and its preparation and use for extracting Cd 2+ and Pb 2+ method.

[0006] The technical purpose of the present invention is achieved through the following technical solutions.

[0007] The diammonium cation ionic liquid containing thioether is composed of diammonium cation and thioether anion; wherein the diammonium cation molecular formula is C 19 H 44 N2 2+ , referred to as HxPrHx, the structural formula is as follows

[0008]

[0009] The sulfur-containing ether anion is one of 2-mercaptobenzoate (TS), S-benzyl-benzoate (BTB), S-methyl-benzoate (MTBA), 2,2'-dithiodibenzoate (DTSA) or 5,5'-dithiobis(2-nitrobenzoate) (DTNB).

[0010] The preparation method of the thioether-containing diammonium cationic ionic liquid of the present invention comprises the following steps:

[0011]

[0012] Step 1: Add the halide C containing the target cation19 H 44 N2Br2 and a thioether-containing acid are stirred to react, anhydrous methanol is selected as the reaction atmosphere, a halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with a thioether-containing compound dissolved or dispersed in anhydrous methanol; the reaction temperature is 40-60°C, and the stirring reaction is performed for 12-24 hours;

[0013] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain an ionic liquid.

[0014] In the above technical solution, the halide C containing the target cation 19 H 44 The molar ratio of N2Br2 to the thioether-containing acid R1-H is 1:(2-2.5), the thioether-containing acid R1-H includes 2-mercaptobenzoic acid, S-benzyl-benzoic acid or S-methyl-benzoic acid; the halide C containing the target cation 19 H 44 The molar ratio of N2Br2 to the thioether-containing acid H-R3-H is 1:(1-1.5), and the thioether-containing acid H-R3-H includes 2,2'-dithiodibenzoic acid or 5,5'-dithiobis(2-nitrobenzoic acid).

[0015] In the above technical solution, the halide containing the target diammonium cation (molecular formula C 19 H 44 N2Br2) has the following structural formula:

[0016]

[0017] The halide of the diammonium cation has two bromide ions and is named N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanediammonium bromide ([HxPrHx][Br]2).

[0018] The sulfide-containing diammonium cationic ionic liquid of the present invention is used to extract Cd from aqueous solution 2+ and Pb 2+ ion.

[0019] The sulfide-containing diammonium cationic ionic liquid of the present invention is used to extract Cd from aqueous solution 2+ and Pb 2+ The ion extraction method comprises the following steps:

[0020] (1) Cd 2+ and Pb 2+ The aqueous solution is placed in a container, and a diammonium cation ionic liquid containing a thioether is added to extract Cd from the aqueous solution using the ionic liquid. 2+ and Pb 2+ .

[0021] (2) Filter the ionic liquid after the extraction is completed.

[0022] In the above technical solution, the diammonium cationic ionic liquid separated by filtration is washed and regenerated and then returned to step (1) for secondary utilization.

[0023] In the above technical solution, the diammonium cationic ionic liquid separated by filtration is regenerated by flushing with HNO3 and NaHCO3 in sequence.

[0024] In the above technical solution, the concentration of the HNO3 solution used is controlled at 0.1-0.5 mol / L, and NaHCO3 is a saturated solution.

[0025] In the above technical solution, the mass M of the ionic liquid used for extraction is IL (Unit: g) and Cd 2+ and Pb 2+ Heavy metal simulated wastewater volume V 水 (Unit L) Ratio Preferred M IL :V 水 =(8~40):1.

[0026] In the above technical solution, the container is shaken by a shaker, and the shaking process is the ionic liquid to the Cd 2+ and Pb 2+ The extraction process of ions.

[0027] In the above technical solution, the extraction temperature is room temperature, the extraction pH is controlled to pH=3.5-13.5 by HNO3 and NaOH solution, and the extraction time is controlled to 1-240 min.

[0028] The novel diammonium cation ionic liquid containing thioether of the present invention has the following characteristics compared with the ionic liquid reported in the literature: (1) diquaternary ammonium salts are used as dications, which have good thermal stability and are solid at room temperature and pressure, which is conducive to the rapid separation of the extraction phase and the residual phase after the extraction is completed; (2) the introduction of dications increases the number of anions per unit mass, thereby increasing the number of thioethers or thiol groups, increasing the adsorption sites for metal ions, and improving the extraction capacity and rate; (3) the leaching rate of the ionic liquid is low, which avoids the leaching of metal ions into water after the ionic liquid extracts the metal ions, thereby reducing the risk of secondary pollution; (4) the ionic liquid has good thermal stability and is solid at room temperature and pressure, which is conducive to the rapid separation of the extraction phase and the residual phase after the extraction is completed; (5) the ionic liquid has good thermal stability and is solid at room temperature and pressure, which is conducive to the rapid separation of the extraction phase and the residual phase after the extraction is completed; (6) the introduction of dications increases the number of anions per unit mass, thereby increasing the number of thioethers or thiol groups, increasing the adsorption sites for metal ions, and improving the extraction capacity and rate; (7) the ionic liquid has a low leaching rate, which avoids the leaching of metal ions into water after the ionic liquid extracts the metal ions, and reduces the risk of secondary pollution; (8) the ionic liquid has good thermal stability and is easy to be used in the extraction of Cd 2+ and Pb 2+ When the concentration is low, the extraction efficiency is still maintained at a high level. Under the conditions of room temperature, extraction concentration of 5 mg / L and extraction time of 1 min, the ionic liquid has a high extraction efficiency for Cd 2+ and Pb 2+The highest extraction efficiency reached 94.84% and 99.77% respectively, which is the highest level at present; (5) The strong interaction between the electronegative S atoms in the sulfide group and the metal ions makes the ionic liquid have a strong affinity for Cd 2+ and Pb 2+ The extraction capacity of -1 and 0.53mg / g·min -1 , which is at the highest level at present; (6) Cd is stripped by washing with HNO3 and NaHCO3 in sequence 2+ and Pb 2+ The regeneration of the ionic liquid is realized, and the regeneration and utilization of the ionic liquid is realized. DETAILED DESCRIPTION

[0029] The present invention is described in detail through the following embodiments, but is not limited to the following embodiments. All technologies realized based on the above contents of the present invention belong to the technical scope of the present invention.

[0030] Example 1

[0031] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate ([HxPrHx][BTB]2) preparation process, the specific method is as follows:

[0032]

[0033] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanediammonium bromide, 0.01 mol S-benzyl-benzoic acid and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with S-benzyl-benzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 40°C, and the stirring reaction is performed for 12 hours;

[0034] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate. Its structural formula is as follows:

[0035]

[0036] Its nuclear magnetic resonance hydrogen spectrum data is: 1 H NMR (400MHz, MeOD) δ7.67 (dd, J=7.6, 1.2Hz, 1H, H arom ),7.42(d,J=7.3Hz,2H,H arom ),7.38–7.10(m,6H,H arom ),4.87(s,1H),3.09(s,5H,–CH2–),2.50–2.21(m,1H,–CH2–),1.73(s,2H,–CH2–),1.36(d,J=3.2Hz,6H,–CH3),1.03–0.79(m,3H,–CH3). 13 C NMR(101MHz,MeOD)δ173.54,167.18,137.85,137.45,136.80,136.62,132. 11,130.53,129.12,128.86,128.77,128.64,128.21,128.17,128.12,127. 95,127.92,127.81,126.93,126.85,126.84,126.76,126.60,124.90,124.30,124.11,66.53,66.07,65.03,63.83,60.33,51.18,49.96,49.37,48.26 ,48.04,47.83,47.80,47.78,47.77,47.75,47.74,47.72,47.71,47.70,47.67,47.62,47.54,47.53,47.51,47.50,47.48,47.47,47.41,47.37,47.36 ,47.33,47.31,47.30,47.28,47.27,47.25,47.24,47.19,46.98,37.24,36.81,31.03,30.97,25.67,22.20,22.14,22.08,22.03,16.85,12.88,12.85. Its infrared data is: (4000-400cm -1 )3740,3423,3025,2955,2862,1722,1596,1555,1488,1460,1399,1278,1241,1156,1109,1059,1032,977,917,781,737,697.

[0037] Example 2

[0038] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-2,2'-dithiodibenzoate ([HxPrHx][DTSA]), the specific method is as follows:

[0039]

[0040] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.005 mol 2,2'-dithiodibenzoic acid and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with 2,2'-dithiodibenzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 40°C, and the stirring reaction is performed for 16 hours;

[0041] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-2,2'-dithiodibenzoate. Its structural formula is as follows:

[0042]

[0043] Its nuclear magnetic resonance hydrogen spectrum data is: 1 H NMR(400MHz,MeOD)δ7.95–7.83(m,1H,H arom ),7.71(d,J=7.9Hz,1H,H arom ),7.38–7.24(m,1H,H arom ),7.19(t,J=7.2Hz,1H,H arom),3.53–3.35(m,5H,–CH2–),3.34–3.30(m,2H,–CH2–),3.16(s,4H,–CH2–),2.34( s,1H,–CH2–),1.77(s,2H,–CH2–),1.35(s,5H,–CH3),0.91(t,J=6.5Hz,3H,–CH3). 13 C NMR(101MHz,MeOD)δ173.01,137.39,136.50,129.84,129.76,124.96,124.88,65.03,60.34,50.03,48.2 4,48.10,48.03,47.98,47.95,47.89,47.81,47.78,47.76,47.75,47.74,47.72,47.71,47.69,47.68,47. 66,47.65,47.60,47.52,47.51,47.49,47.48,47.47,47.45,47.44,47.39,47.32,47.31,47.29,47.28,47.27,47.25,47.24,47.22,47.17,47.14,47.13,47.11,46.96,31.01,25.67,22.23,22.11,16.91,12.86. Its infrared data is: (4000-400cm -1 )3893,3744,3414,2955,2863,2355,1594,1551,1464,1374,1239,1040,834,751,698,650.

[0044] Example 3

[0045] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(methylthio)benzoate ([HxPrHx][MTBA]2) preparation process, the specific method is as follows:

[0046]

[0047] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.01 mol S-methyl-benzoic acid and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with S-methyl-benzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 50°C, and the reaction is stirred for 20 hours;

[0048] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(methylthio)benzoate. Its structural formula is as follows:

[0049]

[0050] Its infrared data is: (4000-400cm -1 )3897,3745,3650,3417,3161,3013,2956,2863,2450,2362,2450,2362,1691,1590,1464,1398,1250,1144,1041,916,798,750,694,646,537.

[0051] Example 4

[0052] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-mercaptobenzoate ([HxPrHx][TS]2) preparation process, the specific method is as follows:

[0053]

[0054] Step 1: Stir 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanediammonium bromide, 0.01 mol 2-mercaptobenzoic acid and 2 mL sodium methoxide to react, select anhydrous methanol as the reaction atmosphere, dissolve or disperse the halide containing the target diammonium cation in anhydrous methanol, and react with 2-mercaptobenzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 60°C, and the stirring reaction is performed for 24 hours;

[0055] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-mercaptobenzoate. Its structural formula is as follows:

[0056]

[0057] Its infrared data is: (4000-400cm -1 )3621,3443,3356,2956,2928,2861,1694,1586,1564,1465,1439,1416,1375,1316,1288,1258,1215,1145,1045,890,791,742,688,642,557,494.

[0058] Example 5

[0059] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-5,5'-dithiodicarboxylate bis(2-nitrobenzoate) ([HxPrHx][DTNB]) preparation process, the specific method is as follows:

[0060]

[0061] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.005 mol 5,5'-dithiobis(2-nitrobenzoic acid) and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with 5,5'-dithiobis(2-nitrobenzoic acid) dissolved or dispersed in anhydrous methanol; the reaction temperature is 60°C, and the stirring reaction is performed for 12 hours;

[0062] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-5,5'-dithiodiol bis(2-nitrobenzoate). Its structural formula is as follows:

[0063]

[0064] Its infrared data is: (4000-400cm -1 )3897,3745,3444,3185,3013,2954,2925,2862,2362,1762,1622,1563,1527,1466,1350,1239,1150,1098,968,875,853,737.

[0065] Example 6

[0066] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(methylthio)benzoate ([HxPrHx][MTBA]2) preparation process, the specific method is as follows:

[0067]

[0068] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.011 mol S-methyl-benzoic acid and 2 mL sodium methoxide are stirred to react, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with S-methyl-benzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 50°C, and the reaction is stirred for 20 hours;

[0069] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(methylthio)benzoate. Its structural formula is as follows:

[0070]

[0071] Its infrared data is: (4000-400cm -1 )3897,3745,3650,3417,3161,3013,2956,2863,2450,2362,2450,2362,1691,1590,1464,1398,1250,1144,1041,916,798,750,694,646,537.

[0072] Example 7

[0073] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-mercaptobenzoate ([HxPrHx][TS]2) preparation process, the specific method is as follows:

[0074]

[0075] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanediammonium bromide, 0.0125 mol 2-mercaptobenzoic acid and 2 mL sodium methoxide are stirred to react, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with 2-mercaptobenzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 60°C, and the reaction is stirred for 24 hours;

[0076] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-mercaptobenzoate. Its structural formula is as follows:

[0077]

[0078] Its infrared data is: (4000-400cm -1 )3621,3443,3356,2956,2928,2861,1694,1586,1564,1465,1439,1416,1375,1316,1288,1258,1215,1145,1045,890,791,742,688,642,557,494.

[0079] Example 8

[0080] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-5,5'-dithiodicarboxylate bis(2-nitrobenzoate) ([HxPrHx][DTNB]) preparation process, the specific method is as follows:

[0081]

[0082] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.006 mol 5,5'-dithiobis(2-nitrobenzoic acid) and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with 5,5'-dithiobis(2-nitrobenzoic acid) dissolved or dispersed in anhydrous methanol; the reaction temperature is 60°C, and the stirring reaction is performed for 12 hours;

[0083] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-5,5'-dithiodiol bis(2-nitrobenzoate). Its structural formula is as follows:

[0084]

[0085] Its infrared data is: (4000-400cm -1 )3897,3745,3444,3185,3013,2954,2925,2862,2362,1762,1622,1563,1527,1466,1350,1239,1150,1098,968,875,853,737.

[0086] Example 9

[0087] This embodiment relates to a diammonium-based cationic ionic liquid N containing a thioether 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-2,2'-dithiodibenzoate ([HxPrHx][DTSA]), the specific method is as follows:

[0088]

[0089] Step 1: 0.005 mol N,N'-dihexyl-N,N,N',N'-tetramethyl-1,3-propanedibromide, 0.0075 mol 2,2'-dithiodibenzoic acid and 2 mL sodium methoxide are stirred for reaction, anhydrous methanol is selected as the reaction atmosphere, the halide containing the target diammonium cation is dissolved or dispersed in anhydrous methanol, and reacted with 2,2'-dithiodibenzoic acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 40°C, and the stirring reaction is carried out for 16 hours;

[0090] Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain ionic liquid N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-2,2'-dithiodibenzoate. Its structural formula is as follows:

[0091]

[0092] Its infrared data is: (4000-400cm -1 )3893,3744,3414,2955,2863,2355,1594,1551,1464,1374,1239,1040,834,751,698,650.

[0093] Embodiments 10 to 14

[0094] (1) Add 5 mL of 5.00 mg / L Cd 2+ and Pb 2+ The aqueous solution is placed in a container, 100 mg of the ionic liquids in Examples 1 to 5 are added, the pH value is adjusted to 7.5, and the sample is placed in a shaker and shaken for 1 to 240 minutes.

[0095] (2) Filter the ionic liquid after shaking.

[0096] The final Cd 2+ and Pb 2+ The extraction effects are shown in Table 1.

[0097] Table 1 Effects of different sulfide-containing dicationic ionic liquids on Cd 2+ , Pb 2+ Extraction effect

[0098]

[0099]

[0100] Examples 15 to 20

[0101] (1) Add 5 mL of 5.00 mg / L Cd 2+ and Pb 2+ The aqueous solution was placed in a container and 100 mg of ionic liquid N was added. 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate, the extraction pH is controlled to pH = 3.5-13.5 by HNO3 and NaOH solution, and placed in a shaker for 60 minutes.

[0102] (2) Filter the ionic liquid after shaking.

[0103] The final ionic liquid has a strong affinity for Cd at different pH values. 2+ and Pb 2+ The extraction effects are shown in Table 2.

[0104] Table 2N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate 2+ and Pb 2+ Extraction effect

[0105]

[0106] Examples 21 to 25

[0107] (1) 2.5, 5, 7.5, 10, and 12.5 mL of 5.00 mg / L Cd 2+ and Pb 2+ The aqueous solution was placed in a container and 100 mg of ionic liquid N was added. 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylsulfide)

[0108] Benzoate, pH adjusted to 7.5, placed in a shaker for 60 min.

[0109] (2) Filter the ionic liquid after shaking.

[0110] Finally, the ionic liquid was obtained to determine the effect of different initial volumes of heavy metal solutions on Cd 2+ and Pb 2+ The extraction effects are shown in Table 3.

[0111] Table 3N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate 2+ and Pb 2+ Extraction effect

[0112]

[0113] Embodiment 26

[0114] This embodiment involves N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 Effect of -tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate on Cd in heavy metal aqueous solution 2+ and Pb 2+ The extraction process and secondary utilization of the product are as follows:

[0115] (1) Add 5 mL of 5.00 mg / L Cd 2+ and Pb 2+ The aqueous solution was placed in a container and 100 mg N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate, the pH value was adjusted to 7.5, and the sample was placed in a shaker for extraction for 60 min.

[0116] (2) Filter the ionic liquid after shaking.

[0117] After filtration, N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3-tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate was washed with 0.1-0.5 mol / L HNO3 solution and saturated NaHCO3 solution respectively and then returned to step (1) for secondary utilization. 2+ and Pb 2+ The extraction efficiency is shown in Table 4.

[0118] Table 4 The effects of ionic liquids on the Cd content in heavy metal solutions during secondary utilization 2+ and Pb 2+ The extraction efficiency

[0119]

[0120]

[0121] Embodiment 27

[0122] N was analyzed by Multiwfn software 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -tetramethylpropane-1,3-diamino-2-(benzylthio)benzoate ([HxPrHx][BTB]) and N 1 ,N 3 -Dihexyl-N 1 ,N 1 ,N 3 ,N 3 -Tetramethylpropane-1,3-diamine-2,2'-dithiodibenzoate ([HxPrHx][DTSA]) extraction of Cd 2+ The structure after extraction shows that heavy metal Cd 2+ The mechanism of absorption includes both physical and quasi-chemical absorption, as shown in Table 5.

[0123] Table 5 Topological parameters at the BCP of ionic liquid MO and MS bonds (unit: au)

[0124]

[0125] According to the present invention, the preparation of the ionic liquid of the present invention can be achieved by adjusting the parameters, and the ionic liquid exhibits the same performance as the present invention, that is, it exhibits the same performance as the ionic liquid of the present invention. 2+ and Pb 2+ The above is an exemplary description of the present invention. It should be noted that any simple deformation, modification or other equivalent replacement that can be made by a person skilled in the art without inventive labor without departing from the core of the present invention falls within the protection scope of the present invention.

Claims

1. A sulfide-containing diammonium cationic ionic liquid, characterized in that: It is composed of diammonium cations and sulfur-containing ether anions, where the diammonium cation molecular formula is C 19 H 44 N2 2+ , the structural formula is as follows: The sulfur-containing ether anion is one of 2-mercaptobenzoate, S-benzyl-benzoate, S-methyl-benzoate, 2,2'-dithiodibenzoate or 5,5'-dithiobis(2-nitrobenzoate).

2. The method for preparing a sulfide-containing diammonium cationic ionic liquid according to claim 1, characterized in that The steps include: Step 1: Select anhydrous methanol as the reaction atmosphere and react the halide C containing the target diammonium cation 19 H 44 N2Br2 is dissolved or dispersed in anhydrous methanol, and stirred to react with the thioether-containing acid dissolved or dispersed in anhydrous methanol; the reaction temperature is 40-60°C, and the stirring reaction is carried out for 12-24 hours; Step 2: After the reaction is completed, the reaction system is subjected to rotary evaporation, washing and vacuum drying to obtain an ionic liquid.

3. The method for preparing the sulfide-containing diammonium cationic ionic liquid according to claim 2, characterized in that Halide C containing the target cation 19 H 44 The molar ratio of N2Br2 to the thioether-containing acid R1-H is 1:(2-2.5), the thioether-containing acid R1-H includes 2-mercaptobenzoic acid, S-benzyl-benzoic acid or S-methyl-benzoic acid; the halide C containing the target cation 19 H 44 The molar ratio of N2Br2 to the thioether-containing acid H-R3-H is 1:(1-1.5), and the thioether-containing acid H-R3-H includes 2,2'-dithiodibenzoic acid or 5,5'-dithiobis(2-nitrobenzoic acid).

4. The sulfide-containing diammonium cationic ionic liquid according to claim 1 is used to extract Cd from aqueous solution 2+ and Pb 2+ ion.

5. The diammonium cation ionic liquid containing thioether as claimed in claim 4 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that The following steps are involved: (1) Cd 2+ and Pb 2+ The aqueous solution is placed in a container, and a diammonium cation ionic liquid containing a thioether is added to extract Cd from the aqueous solution using the ionic liquid. 2+ and Pb 2+ ; (2) Filter the ionic liquid after the extraction is completed.

6. The diammonium cation ionic liquid containing thioether as claimed in claim 5 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that filtering The separated diammonium cationic ionic liquid is washed and regenerated with HNO3 and NaHCO3 in sequence and then returned to step (1) for secondary utilization.

7. The diammonium cation ionic liquid containing thioether as claimed in claim 6 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that The concentration of the HNO3 solution used is controlled at 0.1-0.5 mol / L, and the NaHCO3 is a saturated solution.

8. The sulfide-containing diammonium cationic ionic liquid according to claim 5 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that The mass of ionic liquid used for extraction is M IL The unit is g, and the Cd content 2+ and Pb 2+ Heavy metal simulated wastewater volume V 水 Unit is L ratio M IL :V 水 =8~40:

1.

9. The sulfide-containing diammonium cationic ionic liquid according to claim 5 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that The extraction temperature is controlled within the range of 10 to 35°C from room temperature, and the extraction pH is controlled to pH 3.5 to 13.5 by HNO3 and NaOH solution. The extraction process uses a shaker to shake the container. The shaking process is the ionic liquid to Cd in the aqueous solution. 2+ and Pb 2+ The extraction time of the ions is controlled to be 1 to 240 minutes.

10. The diammonium cation ionic liquid containing thioether as claimed in claim 5 is used to extract Cd from aqueous solution 2+ and Pb 2+ The method is characterized in that The extraction mechanism combines physical and quasi-chemical absorption effects.

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