A high ionic density polyionic liquid adsorbent and a method for its preparation and recovery of platinum (IV)

Abstract

The application belongs to the technical field of noble metal separation, and particularly relates to a high-ionic-density polyionic liquid adsorbent and a method for recovering platinum (IV). The application first synthesizes a double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions through a quaternary ammonium reaction of triethylene diamine with 1,3-dichloropropane and 4-chloromethylstyrene. Then, the high-ionic-density polyionic liquid is further synthesized as a platinum (IV) adsorbent through a free radical polymerization reaction. The application has simple preparation process and low raw material cost. The obtained adsorbent has high ionic density and good swelling performance, can efficiently and quickly recover platinum (IV) in a solution, and exhibits excellent adsorption effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of noble metal separation, and particularly relates to a high-ionic-density polyionic liquid adsorbent and a method for recovering platinum (IV). BACKGROUND

[0002] Platinum is widely used in industrial catalysis, fuel cells, biological medicine, jewelry and other fields due to its excellent catalytic activity, chemical stability and excellent electrical and thermal conductivity. However, the global platinum metal reserves are extremely low and extremely unevenly distributed, mainly concentrated in two regions of South Africa and Russia. China is extremely short of platinum resources, accounting for only 0.4% of the world. At present, the supply and demand relationship of platinum resources in China is unbalanced, and more than 90% of platinum resources need to rely on imports. Therefore, in order to reduce the dependence on limited natural resources and improve the utilization rate of metal resources, it is of great significance to actively develop the recovery of platinum metal from secondary resources.

[0003] So far, researchers have reported a variety of recovery technologies for recovering platinum (IV), including ion exchange, chemical precipitation, membrane filtration, electrochemistry, adsorption and other methods. Among these methods, the adsorption method is highly praised by the industry due to its wide range of applications, simple operation, significant economic benefits and environmental protection. Today, many adsorbents have been used to recover platinum (IV), such as porous organic polymers, nanomaterials, graphene oxide, metal-organic framework materials, membrane materials, etc. Although significant progress has been made in this field, unfortunately, most of the adsorbents have the disadvantages of poor acid stability, complicated synthesis steps, high cost and possible secondary pollution, which limits their industrial application. Therefore, there is an urgent need to develop a new type of adsorbent that integrates super strong acid resistance, low cost, simple synthesis and green environmental protection.

[0004] Due to its strong stability, green environmental protection and structure adjustment, polyionic liquid is widely used in the field of environment and is expected to solve the above problems. It is particularly noteworthy that there are various interaction forces between polyionic liquid and noble metal ions, such as electrostatic interaction and van der Waals force, which make polyionic liquid a promising and extremely attractive candidate material in the field of noble metal adsorption. Although great progress has been made in the field of polyionic liquid recovery of platinum (IV), however, there are two problems to be solved at present: (1) the ion density of the prepared polyionic liquid adsorbent is generally small, which leads to relatively low adsorption capacity of platinum (IV); (2) the adsorption kinetics of the prepared polyionic liquid adsorbent for platinum (IV) is relatively slow, and the equilibrium time is relatively long. If the above problems can be effectively solved, it will further promote the development of polyionic liquid in this field. SUMMARY

[0005] In order to solve the problems in the prior art, the purpose of the present application is to provide a high ionic density polyionic liquid adsorbent and a method for recovering platinum (IV). The present application first synthesizes a double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions through quaternization reaction of triethylene diamine with 1,3-dichloropropane and 4-chloromethylstyrene. Then, the high ionic density polyionic liquid is further synthesized as an adsorbent for platinum (IV) through free radical polymerization reaction. The present application has simple preparation process and low raw material cost. The obtained adsorbent has high ionic density and good swelling performance, can efficiently and quickly recover platinum (IV) in solution, and exhibits excellent adsorption effect.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] In the first aspect, the present application provides a high ionic density polyionic liquid adsorbent. The polyionic liquid is a double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions, which is synthesized through free radical polymerization reaction. The high ionic density polyionic liquid adsorbent has the following formula I:

[0008]

[0009] Formula I.

[0010] In the formula, n represents the degree of polymerization.

[0011] In the second aspect, the present application provides a preparation method of the high ionic density polyionic liquid adsorbent of the first aspect, which comprises the following steps:

[0012] S1. Under stirring, triethylene diamine and 1,3-dichloropropane are added into acetonitrile solution to perform quaternization reaction. After the reaction is completed, the product is washed with ethyl acetate and diethyl ether, and then vacuum dried to obtain propane-bridged double triethylene diamine ionic liquid.

[0013] S2. The above double triethylene diamine ionic liquid is dissolved in methanol, and heated to reflux under nitrogen atmosphere to perform quaternization reaction. After the reaction is completed, the solvent is removed by rotary evaporation, and then washed with ethyl acetate and diethyl ether. The product is vacuum dried to obtain double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions.

[0014] S3. The double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions is dissolved in ethanol, and azobisisobutyronitrile is added to initiate free radical polymerization. After the reaction is completed, the product is repeatedly washed with anhydrous ethanol and deionized water. Finally, the product is dried in a freeze dryer to obtain the high ionic density polyionic liquid adsorbent.

[0015] Further, the molar ratio of triethylenediamine and 1,3-dichloropropane in step S1 is 3.8-4.2:1, which ensures the excess of triethylenediamine to obtain high-purity dichloropropane substitution product.

[0016] Further, the temperature of the quaternization reaction in step S1 is between 15-30℃, and the reaction time is 10-14h.

[0017] Further, the temperature of the vacuum drying in step S1 is set at 55-65℃, and the duration is 6-10h.

[0018] Further, the molar ratio of bis-triethylenediamine ionic liquid and 4-chloromethylstyrene in step S2 is 1:2.1-2.5, and after the reaction is completed, only the excess 4-chloromethylstyrene needs to be removed by washing to facilitate subsequent processing.

[0019] Further, the temperature of the quaternization reaction in step S2 is set at 70-80℃, and the reaction time is 45-48h.

[0020] Further, the mass ratio of azobisisobutyronitrile and bis-triethylenediamine ionic liquid monomer containing four high-activity nitrogen positive ions in step S3 is 0.02:1.

[0021] Further, the temperature of the radical polymerization reaction in step S3 is maintained at 75℃, and the reaction time is 22-26h.

[0022] Further, the time of freeze-drying in step S3 is set at 22-26h.

[0023] In a third aspect, the application provides the use of the high-ionic-density polyionic liquid adsorbent of the first aspect in the efficient and rapid recovery of platinum(IV). The maximum adsorption capacity of the polyionic liquid adsorbent for platinum(IV) is 603.2mg / g, and the adsorption equilibrium time for platinum(IV) is 2min. After the adsorption is completed, the polyionic liquid adsorbent can realize the desorption and regeneration of the polyionic liquid.

[0024] In a fourth aspect, the application provides a method for recovering platinum(IV) using the high-ionic-density polyionic liquid adsorbent, comprising the following steps:

[0025] The high-ionic-density polyionic liquid adsorbent of the first aspect is dispersed in a solution containing platinum(IV) and placed in a constant-temperature oscillator to shake and mix them thoroughly, thereby realizing the adsorption of platinum(IV). After the adsorption is completed, the loaded platinum(IV) polyionic liquid adsorbent is separated from the solution by centrifugation. The concentration of platinum(IV) in the solution is detected by inductively coupled plasma emission spectrometry, and the adsorption efficiency and adsorption capacity are calculated.

[0026] Further, the high ionic density polyionic liquid is added in an amount of 3-15 mg, the volume of the metal solution is in the range of 3-6 mL, and the concentration of hydrochloric acid in the metal solution is in the range of 0.1-4.0 mol / L.

[0027] Further, the temperature of the constant temperature oscillator is in the range of 25-65 DEG C, and the adsorption time is in the range of 0.5-15 min.

[0028] Finally, an acidic thiourea solution is added to the platinum (IV) loaded polyionic liquid to achieve desorption and regeneration of the polyionic liquid. At this time, platinum forms a complex with thiourea to return to the solution, achieving desorption of the polyionic liquid. The desorbed polyionic liquid and the complex solution of platinum and thiourea are separated by centrifugal separation. Finally, the desorbed polyionic liquid is washed with deionized water to remove residual acidic thiourea solution, and the next round of adsorption-desorption-circulation process can be carried out.

[0029] Further, the concentration of thiourea in the acidic thiourea solution is controlled in the range of 45-55 mmol / L, the concentration of hydrochloric acid is maintained in the range of 0.15-0.25 mol / L, and the volume of the acidic thiourea solution is controlled in the range of 5-7 mL.

[0030] The beneficial effects of the present application are:

[0031] (1) The structure unit of the polyionic liquid adsorbent disclosed by the present application has high nitrogen cation density, and the ion exchange capacity reaches 6.21 mmol / g, providing abundant adsorption sites for the adsorbent. This makes the adsorbent exhibit excellent adsorption capacity for platinum (IV), reaching 603.2 mg / g. Compared with the polyionic liquid adsorbents reported in the previous literature, the adsorbent of the present application exhibits significantly improved adsorption capacity.

[0032] (2) In the present application, the structure unit of the polyionic liquid adsorbent is rich in triethylene diamine, which endows the polyionic liquid with good hydrophilicity and swelling property. This helps to make the active sites of the adsorbent fully contact with metal ions during the adsorption process, thereby improving the adsorption rate and achieving adsorption equilibrium in only 2 minutes. Compared with the previously reported polyionic liquids, the polyionic liquid of the present application exhibits significantly improved adsorption rate.

[0033] (3) The polyionic liquid disclosed by the present application has excellent anti-interference ability. In the presence of high concentrations of competitive anions and cations, it still maintains good adsorption performance for platinum.

[0034] (4) The raw materials used in the present application are cheap and easy to obtain, green and environmentally friendly, and the synthesis steps of the polyionic liquid are simple, easy to popularize, and have broad application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of the application, and their

[0036] Figure 1 Fourier transform infrared spectrum of high ionic density poly ionic liquid adsorbent prepared in Example 1 of the present application.

[0037] Figure 2 EDS spectrum of high ionic density poly ionic liquid adsorbent prepared in Example 1 of the present application.

[0038] Figure 3 Water contact angle of high ionic density poly ionic liquid adsorbent prepared in Example 1 of the present application.

[0039] Figure 4 Fourier transform infrared spectrum of high ionic density poly ionic liquid adsorbent prepared in Example 1 of the present application before acid treatment, after 6 mol / L HCl treatment and after 12 mol / L HCl treatment.

[0040] Figure 5 Adsorption isotherm of high ionic density poly ionic liquid adsorbent in Example 6 of the present application for platinum (IV).

[0041] Figure 6 Cyclic stability of high ionic density poly ionic liquid in Example 9 of the present application. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0043] A high ionic density poly ionic liquid adsorbent, which is synthesized by free radical polymerization of a bistrivinyldiamine ionic liquid monomer containing four high active nitrogen cations. The structure of the high ionic density poly ionic liquid adsorbent is shown in Formula I as follows:

[0044]

[0045] Formula I.

[0046] wherein n represents the degree of polymerization.

[0047] The method for preparing the high ionic density poly ionic liquid adsorbent comprises the following steps:

[0048] S1, under stirring, triethylenediamine and 1,3-dichloropropane were added into acetonitrile solution to carry out quaternary ammonium reaction. After the reaction was completed, it was washed by ethyl acetate and diethyl ether, and vacuum dried to obtain propane-bridged double triethylenediamine ionic liquid.

[0049] S2, the above double triethylenediamine ionic liquid and 4-chloromethylstyrene were dissolved in methanol, and heated to reflux under nitrogen atmosphere to carry out quaternary ammonium reaction. After the reaction was completed, the solvent was removed by rotary evaporation, and then washed with ethyl acetate and diethyl ether. After vacuum drying, the double triethylenediamine type ionic liquid monomer containing four high-activity nitrogen positive ions was obtained.

[0050] S3, the above double triethylenediamine type ionic liquid monomer containing four high-activity nitrogen positive ions was dissolved in ethanol, and azobisisobutyronitrile was added to initiate free radical polymerization. After the reaction was completed, it was washed repeatedly with deionized water and anhydrous ethanol. Finally, the product was dried in a freeze dryer to obtain a high ionic density polyionic liquid adsorbent.

[0051] In some embodiments, the molar ratio of triethylenediamine and 1,3-dichloropropane in step S1 is 3.8-4.2:1, ensuring an excess of triethylenediamine to ensure obtaining a high-purity dichloropropane substitution product.

[0052] In some embodiments, the temperature of the quaternary ammonium reaction in step S1 is room temperature, between 15-30°C, and the reaction time is 10-14h.

[0053] In some embodiments, the temperature of the vacuum drying in step S1 is set to 55-65°C for 6-10h.

[0054] In some embodiments, the molar ratio of double triethylenediamine ionic liquid and 4-chloromethylstyrene in step S2 is 1:2.1-2.5, and only the excess 4-chloromethylstyrene needs to be removed after the reaction is completed to facilitate subsequent processing.

[0055] In some embodiments, the temperature of the quaternary ammonium reaction in step S2 is set to 70-80°C, and the reaction time is 45-48h.

[0056] In some embodiments, the mass ratio of azobisisobutyronitrile and double triethylenediamine type ionic liquid monomer containing four high-activity nitrogen positive ions in step S3 is 0.02:1.

[0057] In some embodiments, the temperature of the free radical polymerization reaction in step S3 is maintained at 75°C, and the reaction time is 22-26h.

[0058] In some embodiments, the time of freeze drying in step S3 is set to 22h-26h.

[0059] The application of the above high ionic density polyionic liquid as an adsorbent for recovering platinum (IV) in an aqueous solution includes the following specific steps:

[0060] An appropriate amount of high ionic density polyionic liquid is dispersed into a metal solution, and the two are fully contacted by being placed in a constant temperature oscillator for a period of time. Subsequently, after adsorption equilibrium, centrifugal separation is performed. The concentration of platinum in the aqueous phase is tested by an inductively coupled plasma emission spectrometer, and the adsorption efficiency and the adsorption capacity are calculated.

[0061] In some embodiments, the amount of the high ionic density polyionic liquid added is between 3 and 15 mg, the volume of the metal solution is in the range of 3 to 6 mL, and the concentration of hydrochloric acid in the metal solution is between 0.1 and 4.0 mol·L -1

[0062] In some embodiments, the temperature of the constant temperature oscillator is between 25 and 65°C, and the adsorption time is between 0.5 and 15 min.

[0063] Finally, an acidic thiourea solution is added to the platinum (IV) loaded polyionic liquid to achieve desorption and regeneration of the polyionic liquid. At this time, platinum forms a complex with thiourea to return to the solution, achieving desorption of the polyionic liquid. The desorbed polyionic liquid and the complex solution of platinum and thiourea are separated by centrifugal separation. Finally, the desorbed polyionic liquid is washed with deionized water to remove residual acidic thiourea solution, and the next adsorption-desorption cycle process can be performed.

[0064] In some embodiments, the concentration of thiourea in the acidic thiourea solution is controlled to be between 45 and 55 mmol / L, the concentration of hydrochloric acid is maintained in the range of 0.15 to 0.25 mol / L, and the volume of the acidic thiourea solution is controlled to be 5 to 7 mL.

[0065] The application will be further described in detail below with reference to specific embodiments, and it should be pointed out that the specific embodiments are an explanation of the application rather than a limitation.

[0066] In the following examples, the experimental methods are conventional methods unless otherwise specified.

[0067] After the adsorption and desorption processes are completed, the concentration of the metal in the solution is determined by an inductively coupled plasma emission spectrometer, and the corresponding adsorption efficiency E ), adsorption capacity q e ), and desorption efficiency S% ) are obtained according to the following formulas:

[0068]

[0069] wherein,​C in and C eq (mmol / L) respectively represent the concentration of metal in aqueous solution before and after adsorption, m represents the mass of polyionic liquid adsorbent, V represents the volume of metal solution. n aq and n PIL respectively represent the molar amount of platinum on polyionic liquid before desorption and in acidic thiourea solution after desorption.

[0070] The reagents and materials used in the following examples, unless otherwise specified, can be obtained commercially.

[0071] Example 1

[0072] 1. Synthesis of polyionic liquid adsorbent with high ionic density

[0073] 0.088 mol of triethylenediamine and 0.022 mol of 1,3-dichloropropane were added to 50 ml of acetonitrile solution and stirred at 25°C for 12 h. After the reaction was completed, it was washed with ethyl acetate and diethyl ether for several times, and then dried under vacuum at 65°C for 6 h to obtain propane-bridged bis-triethylenediamine ionic liquid. Next, 0.015 mol of bis-triethylenediamine ionic liquid and 0.031 mol of 4-chloromethylstyrene were dissolved in 50 ml of methanol, and the quaternary ammonium reaction was carried out under a nitrogen atmosphere with a reaction temperature of 80°C and a reaction time of 45 h. After the reaction was completed, the solvent was removed by rotary evaporation, and then washed with ethyl acetate and diethyl ether. After vacuum drying, the monomer of bis-triethylenediamine type ionic liquid containing four high-activity nitrogen cations, referred to as [2DVB-C3DABCO]Cl4, was obtained. 1.0 g of the obtained monomer was dissolved in ethanol, 20 mg of azobisisobutyronitrile was added, and radical polymerization was initiated at 75°C for 24 h. After the reaction was completed, ethanol and deionized water were used for repeated washing. Finally, the product was placed in a freeze dryer for drying for 24 h to obtain a polyionic liquid adsorbent with high ionic density, referred to as P(2DVB-C3DABCO)s.

[0074] The P(2DVB-C3DABCO)s prepared in Example 1 was characterized in detail. By Figure 1 the characteristic peaks of the Fourier transform infrared spectrum, it was proved that the polyionic liquid adsorbent P(2DVB-C3DABCO)s with high ionic density was successfully synthesized. In Figure 2The middle EDS spectrum shows that the nitrogen content of the high ionic density poly-ionic liquid adsorbent is 8.71%. The ion exchange capacity of the poly-ionic liquid adsorbent is 6.21 mmol / g, which is determined by the Mohr titration method. The above high content of nitrogen element and high ion exchange capacity are conducive to improving the adsorption capacity in the adsorption process. In addition, by Figure 3 The results of the water contact angle confirm that the poly-ionic liquid adsorbent prepared by the present application has excellent hydrophilicity and swelling performance. Further experiments show that the swelling ratio of the adsorbent is 5.2 g / g. The above excellent hydrophilicity and swelling are conducive to improving the adsorption rate. In addition, Figure 4 The infrared spectrum shows that the poly-ionic liquid adsorbent treated by high-concentration inorganic acid still maintains good chemical stability.

[0075] Example 2

[0076] 0.085 mol of triethylenediamine and 0.022 mol of 1,3-dichloropropane were added to a 50 ml acetonitrile solution, and stirred at 30°C for 10 h. After the reaction was completed, it was washed with ethyl acetate and diethyl ether for several times, and then dried under vacuum at 60°C for 8 h to obtain a propane-bridged double triethylenediamine ionic liquid. Next, 0.015 mol of double triethylenediamine ionic liquid and 0.036 mol of 4-chloromethylstyrene were dissolved in 50 ml of methanol, and the quaternary ammonium reaction was carried out under a nitrogen atmosphere, with a reaction temperature of 70°C and a reaction time of 48 h. After the reaction was completed, the solvent was removed by rotary evaporation, and then washed with ethyl acetate and diethyl ether. After vacuum drying, a double triethylenediamine type ionic liquid monomer containing four high-activity nitrogen positive ions was obtained, which was referred to as [2DVB-C3DABCO]Cl4. 1.0 g of the obtained monomer was dissolved in ethanol, 20 mg of azobisisobutyronitrile was added, and the reaction was initiated at 75°C for 22 h to initiate free radical polymerization. After the reaction was completed, ethanol and deionized water were used for repeated washing. Finally, the product was placed in a freeze dryer for drying for 22 h to obtain a high ionic density poly-ionic liquid adsorbent, which was referred to as P(2DVB-C3DABCO)s.

[0077] Example 3

[0078] To 50 ml of acetonitrile solution, 0.092 mol of triethylenediamine and 0.022 mol of 1,3-dichloropropane were added, and stirred at 15°C for 14 h. After the reaction was completed, it was washed with ethyl acetate and diethyl ether several times, and then dried under vacuum at 55°C for 10 h to obtain propane-bridged bis-triethylenediamine ionic liquid. Next, 0.015 mol of bis-triethylenediamine ionic liquid and 0.034 mol of 4-chloromethylstyrene were dissolved in 50 ml of methanol, and the quaternary ammonium reaction was carried out under a nitrogen atmosphere by heating to reflux, with a reaction temperature of 75°C and a reaction time of 46 h. After the reaction was completed, the solvent was removed by rotary evaporation, and then washed with ethyl acetate and diethyl ether. After vacuum drying, a monomer of bis-triethylenediamine type ionic liquid containing four high-activity nitrogen positive ions, referred to as [2DVB-C3DABCO]Cl4, was obtained. 1.0 g of the obtained monomer was dissolved in ethanol, 20 mg of azobisisobutyronitrile was added, and radical polymerization was initiated at 75°C for 26 h. After the reaction was completed, it was washed repeatedly with ethanol and deionized water. Finally, the product was dried in a freeze dryer for 26 h to obtain a high ionic density poly-ionic liquid adsorbent, referred to as P(2DVB-C3DABCO)s.

[0079] Example 4

[0080] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0081] A 5 mmol / L aqueous solution of chloroplatinic acid was prepared, and the concentration of hydrochloric acid was adjusted to 0.1 mol / L. 6 mL of the above platinum (IV) solution was taken in a 7 ml centrifuge tube. 3 mg, 6 mg, 9 mg, 12 mg, 15 mg of high ionic density poly-ionic liquid adsorbent prepared in Example 1 was added, respectively, and then placed in a constant temperature oscillator at 25°C for 15 min. After the adsorption reached equilibrium, the poly-ionic liquid adsorbent and the metal solution were separated into two phases by centrifugation for 3 min using a centrifuge. Finally, the concentration of platinum (IV) in the upper aqueous solution was detected by inductively coupled plasma emission spectrometry, and the adsorption efficiency was calculated. As shown in Table 1, with the addition of high ionic density poly-ionic liquid adsorbent, the adsorption efficiency of platinum showed an upward trend, and finally gradually stabilized.

[0082] Table 1 Adsorption efficiency of different mass of poly-ionic liquid adsorbent on platinum (IV)

[0083] .

[0084] Example 5

[0085] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0086] A 5 mmol / L aqueous solution of chloroplatinic acid was prepared, and the concentration of hydrochloric acid was adjusted to 0.1 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, and 4.0 mol / L, respectively. Next, 6 mL of the above platinum (IV) solution was taken in a 7 ml centrifuge tube. 6 mg of the high ionic density polymeric ionic liquid adsorbent prepared in Example 1 was added, and then placed in a constant temperature oscillator at 25°C for oscillation for 15 min. After the adsorption reached equilibrium, the polymeric ionic liquid adsorbent and the metal solution were separated into two phases by centrifugation for 3 min using a centrifuge. Finally, the concentration of platinum (IV) in the upper aqueous solution was detected by inductively coupled plasma emission spectrometry, and the adsorption capacity was calculated. As shown in Table 2, with the increase of the concentration of hydrochloric acid, the adsorption capacity of platinum gradually decreased. Therefore, in order to optimize the adsorption capacity, the concentration of hydrochloric acid in the platinum solution was maintained at 0.1 mol / L in the subsequent experiments.

[0087] Table 2 Adsorption capacity of polymeric ionic liquid adsorbent for platinum (IV) at different concentrations of hydrochloric acid

[0088] .

[0089] Example 6

[0090] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0091] A 5 mmol / L aqueous solution of chloroplatinic acid was prepared, and the concentration of hydrochloric acid was adjusted to 0.1 mol / L. Next, 6 mL of the above platinum (IV) solution was taken in a 7 ml centrifuge tube. 6 mg of the high ionic density polymeric ionic liquid adsorbent prepared in Example 1 was added, and then placed in a constant temperature oscillator at 25°C for oscillation for 0.5 min, 1 min, 2 min, 3 min, 5 min, 7 min, and 10 min, respectively

[0092] , 15 min. After the adsorption was completed, the polymeric ionic liquid adsorbent and the metal solution were separated into two phases by centrifugation for 1 min using a centrifuge. Finally, the concentration of platinum (IV) in the upper aqueous solution was tested, and the adsorption capacity was calculated. According to Table 3, the adsorption reached equilibrium in 2 min, and such a rapid adsorption rate can be attributed to the good swelling performance of the polymeric ionic liquid adsorbent prepared in the present application, which facilitates the full contact of the adsorption sites with metal ions. Compared with other polymeric ionic liquid adsorbents reported in the literature, the adsorbent prepared in the present application has a significant advantage in terms of adsorption rate.

[0093] Table 3 Adsorption capacity of polymeric ionic liquid adsorbent for platinum (IV) at different adsorption times

[0094] .

[0095] Example 7

[0096] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0097] An aqueous solution of chloroplatinic acid with an initial concentration of 5 mmol / L was prepared and adjusted to a hydrochloric acid concentration of 0.1 mol / L. Next, 6 mL of the above platinum (IV) solution was taken in a 7 mL centrifuge tube. 6 mg of the high ionic density poly-ionic liquid adsorbent prepared in Example 1 was added, followed by placing in a constant temperature shaker at 25 °C, 35 °C, 45 °C, 55 °C, 65 °C, respectively, and shaken for 15 min. After the adsorption reached equilibrium, the poly-ionic liquid adsorbent and the metal solution were separated into two phases by centrifugation for 3 min using a centrifuge. Finally, the concentration of platinum (IV) in the upper aqueous solution was tested to calculate the adsorption capacity. As shown in Table 4, the adsorption capacity of platinum (IV) gradually increased with the increase of the adsorption temperature, which indicated that the adsorption process described in the present application was a typical endothermic process.

[0098] Table 4 Adsorption capacity of platinum (IV) by the poly-ionic liquid adsorbent at different adsorption temperatures

[0099] .

[0100] Example 8

[0101] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0102] An aqueous solution of chloroplatinic acid with an initial concentration of 5 mmol / L was prepared and adjusted to a hydrochloric acid concentration of 0.1 mol / L. Next, 6 mL of the above platinum (IV) solution was taken in a 7 mL centrifuge tube. 6 mg of the high ionic density poly-ionic liquid adsorbent prepared in Example 1 was added, followed by placing in a constant temperature shaker at 25 °C, 35 °C, 45 °C, 55 °C, 65 °C, respectively, and shaken for 15 min. After the adsorption reached equilibrium, the poly-ionic liquid adsorbent and the metal solution were separated into two phases by centrifugation for 3 min using a centrifuge. Finally, the concentration of platinum (IV) in the upper aqueous solution was tested to calculate the adsorption capacity. As shown in Table 4, the adsorption capacity of platinum (IV) gradually increased with the increase of the adsorption temperature, which indicated that the adsorption process described in the present application was a typical endothermic process. Figure 5 As shown in Table 4, the adsorption capacity of platinum (IV) gradually increased with the increase of the adsorption temperature, which indicated that the adsorption process described in the present application was a typical endothermic process. 20.972 and 0.937, respectively, indicating that the adsorption process followed the Langmuir model, and the process was monolayer adsorption on a uniform surface. According to the fitting parameters of the Langmuir adsorption isotherm, the maximum adsorption capacity of the polymeric ionic liquid adsorbent prepared in the application for platinum (IV) was 603.2 mg / g. Compared with other polymeric ionic liquid adsorbents reported in the literature, the adsorbent prepared in the application had a significant advantage in the adsorption capacity for platinum (IV).

[0103] Example 9

[0104] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0105] An aqueous solution of chloroplatinic acid with an initial concentration of 5 mmol / L was prepared, and the hydrogen ion concentration was fixed at 0.1 mol / L. Subsequently, different amounts of NaCl, NaNO3, Na2SO4 were gradually added to the above solution to adjust the Cl - , NO3 - , SO4 2- concentrations to 0.1, 0.45, 0.8, 1.15, 1.5 mol / L, respectively. Next, 6 mL of the above platinum (IV) solution was taken into a 7 ml centrifuge tube. 15 mg of the high ionic density polymeric ionic liquid adsorbent prepared in Example 1 was added, and then placed in a constant temperature oscillator at 25°C for 15 min. After the adsorption reached equilibrium, the polymeric ionic liquid adsorbent and the metal solution were separated by centrifugation for 3 min using a centrifuge. Finally, the upper aqueous solution was taken to test the concentration of platinum (IV), and the adsorption capacity was calculated. As shown in Table 5, NO3 - had the most significant effect on the adsorption capacity of the adsorbent, followed by Cl - , and SO4 2- had the least effect.

[0106] Table 5 Adsorption capacity of polymeric ionic liquid adsorbent for platinum (IV) under different anion concentrations

[0107] .

[0108] Example 10

[0109] Adsorption of platinum (IV) using P(2DVB-C3DABCO)s prepared in Example 1

[0110] A multi-metallic mixed solution containing platinum (IV), copper (II), iron (III), and manganese (II) was prepared, with a platinum concentration of 50 mmol / L and the concentration of other coexisting metal ions of 200 mmol / L. The hydrochloric acid concentration was adjusted to 0.1 mol / L. Next, 6 mL of the above platinum (IV) solution was placed in 7 mL centrifuge tubes. 15 mg of the high ion density polyionic liquid adsorbent prepared in Example 1 was added to each tube, and then the tubes were shaken in a constant-temperature shaker at 25°C for 15 min. After adsorption equilibrium was reached, the tubes were centrifuged for 3 min to achieve two-phase separation of the polyionic liquid adsorbent and the metal solution. Finally, the concentration of platinum (IV) in the supernatant was measured, and the adsorption efficiency was calculated. As shown in Table 6, the adsorption efficiency of the polyionic liquid adsorbent for platinum (IV) was 98.73%, while the adsorption efficiencies for other interfering metals were all below 2%. Therefore, the polyionic liquid adsorbent prepared in this invention exhibits excellent selectivity for platinum (IV).

[0111] Table 6. Selectivity of polyionic liquid adsorbents for different metal ions

[0112] .

[0113] Example 11

[0114] Desorption and regeneration of high ion density polyionic liquid adsorbents

[0115] Six mL of acidic thiourea solution (45 mmol / L thiourea, 0.2 mol / L hydrochloric acid) was added to a platinum (IV)-loaded polyionic liquid adsorbent to achieve desorption and regeneration of the polyionic liquid. During this process, platinum forms a complex with thiourea and returns to the solution, thus achieving desorption of the polyionic liquid. The desorbed polyionic liquid and the platinum-thiourea complex solution were separated by centrifugation. Finally, the desorbed polyionic liquid was washed with deionized water to remove residual acidic thiourea solution, allowing for the next adsorption-desorption-cycle process. The calculated desorption efficiency of platinum (IV) was 99.6%.

[0116] The above adsorption-desorption-cycling process was repeated five times consecutively, and the adsorption capacity of each cycle was tested. Figure 6 As shown, after five consecutive uses, its adsorption capacity remained above 535 mg / g. These results demonstrate that the polyionic liquid adsorbent prepared in this invention exhibits excellent cyclic stability.

[0117] Example 12

[0118] Desorption and regeneration of high ion density polyionic liquid adsorbents

[0119] In the platinum (IV) loaded polyionic liquid adsorbent, 5 mL of acidic thiourea solution was added to achieve the desorption and regeneration of the polyionic liquid. The concentration of thiourea was 55 mmol / L and the concentration of hydrochloric acid was 0.15 mol / L. In this process, platinum formed a complex with thiourea and returned to the solution, achieving the desorption of the polyionic liquid. The desorbed polyionic liquid and the complex solution of platinum and thiourea were separated by centrifugal separation. Finally, the desorbed polyionic liquid was washed with deionized water to remove the residual acidic thiourea solution, and the next adsorption-desorption-cycle process could be carried out. The desorption efficiency of platinum (IV) was calculated to be 99.4%.

[0120] Example 13

[0121] Desorption and regeneration of polyionic liquid adsorbent with high ion density

[0122] In the platinum (IV) loaded polyionic liquid adsorbent, 7 mL of acidic thiourea solution (the concentration of sulfuric acid was 50 mmol / L and the concentration of hydrochloric acid was 0.25 mol / L) was added to achieve the desorption and regeneration of the polyionic liquid. In this process, platinum formed a complex with thiourea and returned to the solution, achieving the desorption of the polyionic liquid. The desorbed polyionic liquid and the complex solution of platinum and thiourea were separated by centrifugal separation. Finally, the desorbed polyionic liquid was washed with deionized water to remove the residual acidic thiourea solution, and the next adsorption-desorption-cycle process could be carried out. The desorption efficiency of platinum (IV) was calculated to be 99.1%.

Claims

1. A high ionic density polyionic liquid sorbent, characterized in that: The polyionic liquid adsorbent is synthesized by free radical polymerization of a double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions, and the high-ionic-density polyionic liquid adsorbent has a structural formula as shown in the following formula I: Formula I, wherein n represents a polymerization degree; The preparation method of the high-ionic-density polyionic liquid adsorbent comprises the following steps: S1. Under stirring, triethylene diamine and 1,3-dichloropropane are added into an acetonitrile solution to perform a quaternary ammonium reaction, after the reaction is completed, the product is washed by ethyl acetate and diethyl ether, and then vacuum drying is performed to obtain a propane-bridged double triethylene diamine ionic liquid; S2. The double triethylene diamine ionic liquid is dissolved in methanol together with 4-chloromethylstyrene, and a quaternary ammonium reaction is performed under heating reflux in a nitrogen atmosphere, after the reaction is completed, the solvent is removed by rotary evaporation, and then the product is washed by ethyl acetate and diethyl ether to obtain a double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions; S3. The double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions is dissolved in ethanol, and azobisisobutyronitrile is added to initiate free radical polymerization, after the reaction is completed, the product is repeatedly washed by anhydrous ethanol and deionized water, and finally the product is dried in a freeze dryer to obtain a high-ionic-density polyionic liquid adsorbent.

2. The high ionic density polyionic liquid sorbent of claim 1, wherein: In step S1, the molar ratio of triethylene diamine and 1,3-dichloropropane is 3.8-4.2:1, the quaternary ammonium reaction is performed at a temperature of 15-30℃ for 10-14h, and the vacuum drying is performed at a temperature of 55-65℃ for 6-10h.

3. The high ionic density polyionic liquid sorbent of claim 1, wherein: In step S2, the molar ratio of the double triethylene diamine ionic liquid and 4-chloromethylstyrene is 1:2.1-2.5, and the quaternary ammonium reaction is performed at a temperature of 70-80℃ for 45-48h.

4. The high ionic density polyionic liquid sorbent of claim 1, wherein: In step S3, the mass ratio of azobisisobutyronitrile and the double triethylene diamine ionic liquid monomer containing four high-activity nitrogen positive ions is 0.02:1, the free radical polymerization is performed at a temperature of 75℃ for 22-26h, and the freeze drying is performed for 22-26h.

5. Application of the high-ionic-density polyionic liquid adsorbent of claim 1 to high-efficiency and rapid recovery of platinum (IV).

6. Use of the high ionic density polyionic liquid adsorbent according to claim 5 for efficient and fast recovery of platinum (IV), characterized in that: The maximum adsorption capacity of the polyionic liquid adsorbent for platinum (IV) is 603.2mg / g, the adsorption equilibrium time of the polyionic liquid adsorbent for platinum (IV) is 2min, and after the adsorption is completed, the polyionic liquid adsorbent can also realize desorption and regeneration of the polyionic liquid adsorbent.

7. A method of recovering platinum (IV) using the high ionic density polyionic liquid adsorbent of claim 1, characterized by: The method comprises the following steps: S1. The high-ionic-density polyionic liquid adsorbent is dispersed in a solution containing platinum (IV) and placed in a constant-temperature oscillator to shake and mix the two to realize adsorption of platinum (IV); S2. After the adsorption is completed, the loaded platinum (IV) polyionic liquid adsorbent is separated from the solution by centrifugation; S3, adding acidic thiourea solution in the platinum (IV) loaded polyionic liquid adsorbent, at this time platinum and thiourea form complex back to the solution, achieve desorption of polyionic liquid adsorbent; then through centrifugation to separate the desorption of polyionic liquid adsorbent and platinum and thiourea form complex solution; finally, the desorption of polyionic liquid adsorbent is washed with deionized water to remove residual acidic thiourea solution, that is, the next round of adsorption-desorption-cycle process can be carried out.

8. The method of claim 7, wherein the polyionic liquid adsorbent with high ionic density is used to recover platinum (IV). In step S1, the amount of the polyionic liquid adsorbent with high ionic density is between 3-15 mg, the volume of the metal solution is in the range of 3-6 mL, the concentration of hydrochloric acid in the metal solution is between 0.1-4.0 mol / L; the temperature of the constant temperature oscillator is between 25-65℃, and the adsorption time is between 0.5-15 min.

9. The method of claim 7, wherein the polyion liquid adsorbent has a high ionic density. In step S3, the concentration of thiourea in the acidic thiourea solution is controlled between 45-55 mmol / L, the volume of the acidic thiourea solution is controlled between 5-7 mL, and the concentration of hydrochloric acid is maintained in the range of 0.15-0.25 mol / L.

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