A protein-based adsorbent for selectively adsorbing metal rhenium ions and its application

Abstract

The invention discloses a protein-based adsorbent for selectively adsorbing metal rhenium ions and its application. The adsorbent is obtained by encapsulating alkylamine or ammonium salt in a phase transition aggregate formed by reducing protein with a reducing agent. The method of using the adsorbent is to put the adsorbent into a mixed solution containing rhenium and molybdenum to achieve selective adsorption of rhenium. The preparation and use methods of the adsorbent are simple, environmentally friendly, recyclable, and have a high selective adsorption capacity for rare metal rhenium. The adsorbent can be used for the separation of rhenium and molybdenum in industrial wastewater and ore leachate, and after adsorption-desorption cycles, it still has a high adsorption ratio.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorbents, and in particular relates to a protein-based adsorbent for selectively adsorbing metal rhenium ions formed by doping alkylamine or ammonium salt in phase transition protein. Background Art

[0002] Rhenium is a rare metal with a high melting point. It is widely used in high-temperature alloy production and catalysts in refineries, as well as in high-tech fields such as electronics, astrogeology, and radio medical diagnosis. The market demand for rhenium is increasing worldwide, but its content in the earth's crust is very low (only 10 -7 %). Rhenium minerals are mainly derived from molybdenite, but molybdenite contains metallic molybdenum, which has similar chemical properties and atomic radius to rhenium, and rhenium only contains 200-800 ppm in molybdenite. Therefore, it is very difficult to recover and separate low-concentration (10-100 ppm) rhenium from complexes containing coexisting metal ions, especially when molybdenum is also contained therein.

[0003] There are many technologies for extracting and separating rhenium from molybdenum, such as pyrometallurgy, hydrometallurgy, solvent extraction and ion exchange. However, solvent extraction releases a large amount of organic solvents; pyrometallurgy / hydrometallurgy usually has the problems of high cost and secondary pollution. Adsorption, as another method for extracting and separating rhenium from molybdenum, has gradually been used. Among them, biomass materials are favored because of their sustainability, environmental safety and low cost. For example, aminated corn straw gel, brown algae-based materials and anion exchange resins have been reported for the adsorption of rhenium, but their separation of rhenium and molybdenum in aqueous solution is rarely mentioned. Therefore, it is of great significance to develop new biosorbents with adsorption capacity comparable to that of commercial synthetic adsorbents to overcome the difficulty of effectively separating rhenium in the presence of a large amount of molybdenum, which will also bring great value to rhenium-related industries and materials. Summary of the invention

[0004] The purpose of the present invention is to provide a protein-based adsorbent which has a simple preparation method, is environmentally friendly, has high adsorption efficiency and selectivity for adsorbing metallic rhenium, and provides the application of the adsorbent.

[0005] To achieve the above-mentioned purpose, the protein-based adsorbent used in the present invention is obtained by encapsulating alkylamine or ammonium salt in a phase transition aggregate formed by reducing protein with a reducing agent.

[0006] The alkylamine is any one of di-n-octylamine, n-octylamine, tri-isooctylamine, etc., and the ammonium salt is any one of trimethyltrioctylammonium chloride, octyltrimethylammonium chloride, and dodecyltrimethylammonium chloride.

[0007] The above-mentioned protein is any one of lysozyme, lactalbumin, insulin, serum albumin (human, horse, cattle, rabbit, mouse, sheep), serum, thyrolactoglobulin, transferrin, lactoferrin, fibrinogen, albumin, collagen, keratin, pepsin, β-lactoglobulin, and myoglobin; the reducing agent is any one of tris(2-carboxyethyl)phosphine hydrochloride, cysteine, and glutathione.

[0008] The preparation method of the protein-based adsorbent of the present invention is as follows: dissolving the protein in trifluoroethanol, standing for more than 24 hours, then adding alkylamine or ammonium salt, mixing evenly, then adding reducing agent solution, stirring the obtained mixed solution at 30-40°C until the protein changes from a dissolved state to a phase transition aggregate and wraps the alkylamine or ammonium salt, washing by centrifugation with deionized water, and freeze-drying to obtain the protein-based adsorbent.

[0009] In the above preparation method, the reducing agent concentration in the mixed solution is 0.1-20 mg / mL, the protein concentration is 30-140 mg / mL, and the alkylamine or ammonium salt concentration is 5-80 mg / mL.

[0010] In the above preparation method, it is further preferred that the reducing agent concentration in the mixed solution is 0.4-10 mg / mL, the protein concentration is 50-80 mg / mL, and the alkylamine or ammonium salt concentration is 10-50 mg / mL.

[0011] In the above preparation method, the reducing agent solution is prepared by adding the reducing agent into water and adjusting the pH value to 7 with NaOH.

[0012] The protein-based adsorbent of the present invention is used in the selective adsorption of metal rhenium ions, wherein the metal rhenium ions are derived from any one of copper ore smelting smoke and waste slag, platinum group ore smelting smoke and waste slag, niobium ore smelting smoke and waste slag, zinc ore smelting smoke and waste slag, and low-grade molybdenum ore waste liquid.

[0013] The beneficial effects of the present invention are as follows:

[0014] The present invention dopes alkylamine or ammonium salt into protein, and uses a reducing agent to effectively reduce the disulfide bonds of the protein to induce rapid self-assembly of the protein, thereby obtaining a protein-based adsorbent. The adsorbent can adsorb metal rhenium ions in aqueous solution through the adsorption of metal rhenium ions by the functional adsorption sites of amino residues on amyloid protein aggregates, or the selective action of the quaternary ammonium group of the ammonium salt on metal rhenium ions, and has good selectivity and recyclability, and realizes the separation of rhenium ions and molybdenum ions at low concentrations. Compared with the prior art, the protein-based adsorbent has high selectivity for rhenium ions, and the preparation and use methods are simple and green, and the obtained adsorbent can be recycled, which can solve the problem of separating rhenium ions and molybdenum ions in industrial wastewater and ore leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a digital photograph of the protein-based adsorbent prepared in Example 1.

[0016] Figure 2 is a scanning electron micrograph of the protein-based adsorbent prepared in Example 1.

[0017] Figure 3 is the adsorption rate of rhenium ions and molybdenum ions by the protein-based adsorbent in Example 1 at different pH values.

[0018] Figure 4 It is the adsorption rate of rhenium ions and molybdenum ions at different dosages of the protein-based adsorbent in Example 1.

[0019] Figure 5 It is the adsorption amount of rhenium ions by different dosages of the protein-based adsorbent in Example 1.

[0020] Figure 6 It is a pseudo-second-order fit of the adsorption behavior of the protein-based adsorbent in Example 1.

[0021] Figure 7 is the Freundlich isotherm fit of the adsorption behavior of the protein-based adsorbent in Example 1.

[0022] Figure 8 It is the selective adsorption rate of rhenium ions by the protein-based adsorbent in Example 1 in rhenium / molybdenum binary solutions with different rhenium:molybdenum ratios.

[0023] Fig. 9 It is the adsorption rate of rhenium ions by the protein-based adsorbent in Example 1 in industrial waste liquids with different dilution multiples.

[0024] Fig.10 It is the adsorption ratio of the protein-based adsorbent in Example 1 to rhenium ions and other competing metal ions in industrial wastewater. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0026] Example 1

[0027] 300 mg of lysozyme was dissolved in 3 mL of trifluoroethanol and placed in a 10 mL glass bottle for 24 hours to prepare a 100 mg / L lysozyme solution; then 1 mL of a 180 mg / mL methyl trioctyl ammonium chloride aqueous solution was added to the lysozyme solution, and the solution was shaken at 160 rpm for 30 minutes, and then 0.3 mL of a 129 mg / mL tri(2-carboxyethyl) phosphine hydrochloride solution with a pH of 7 (prepared by dissolving tri(2-carboxyethyl) phosphine hydrochloride in deionized water and adjusting the pH to 7 with a 5 mol / L sodium hydroxide aqueous solution) was added, and the resulting mixed solution was stirred and reacted at 35° C. for 4 hours to transform the lysozyme from a dissolved state to a phase transition aggregate encapsulating the methyl trioctyl ammonium chloride, and then the solution was centrifuged 3 times at a speed of 5000 rpm for a total of 5 minutes with deionized water at room temperature to remove the tri(2-carboxyethyl) phosphine hydrochloride, and then freeze-dried for 24 hours to obtain a dry white powdery protein-based adsorbent.

[0028] Example 2

[0029] 300 mg of lysozyme was dissolved in 3 mL of trifluoroethanol and placed in a 10 mL glass bottle for 24 hours to prepare a 100 mg / L lysozyme solution; then 1 mL of 180 mg / mL methyl trioctyl ammonium chloride aqueous solution was added to the lysozyme solution and shaken at 160 rpm for 30 minutes, and then 0.3 mL of 6 mg / mL tri(2-carboxyethyl) phosphine hydrochloride solution with a pH of 7 (tri(2-carboxyethyl) phosphine hydrochloride was dissolved in deionized water and adjusted to pH 7 with 5 mol / L sodium hydroxide aqueous solution) was added, and the resulting mixed solution was stirred at 35°C for 4 hours to make the lysozyme change from a dissolved state to a phase transition aggregate wrapped with methyl trioctyl ammonium chloride, and then centrifuged 3 times at 5000 rpm for 5 minutes at room temperature with deionized water to remove tri(2-carboxyethyl) phosphine hydrochloride. After centrifugation, the material was freeze-dried for 24 hours to obtain a dry white powder protein-based adsorbent.

[0030] Example 3

[0031] 600 mg of bovine serum albumin is dissolved in 3 mL of trifluoroethanol, and the solution is placed in a 10 mL glass bottle for 24 hours to prepare a 200 mg / L bovine serum albumin solution; then 1 mL of a 180 mg / mL methyl trioctyl ammonium chloride aqueous solution is added to the bovine serum albumin solution, and the solution is shaken at 160 rpm for 30 minutes, and then 0.3 mL of a 129 mg / mL tri(2-carboxyethyl) phosphine hydrochloride solution with a pH of 7 (prepared by dissolving tri(2-carboxyethyl) phosphine hydrochloride in deionized water and adjusting the pH to 7 with a 5 mol / L sodium hydroxide aqueous solution) is added, and the resulting mixed solution is stirred and reacted at 35° C. for 4 hours to transform the bovine serum albumin from a dissolved state into a phase transition aggregate encapsulating the methyl trioctyl ammonium chloride, and then the solution is centrifuged 3 times at a speed of 5000 rpm at room temperature for a total of 5 minutes with deionized water to remove the tri(2-carboxyethyl) phosphine hydrochloride, and then freeze-dried for 24 hours to obtain a dry white powdery protein-based adsorbent.

[0032] Example 4

[0033] 300 mg of lactalbumin was dissolved in 3 mL of trifluoroethanol and placed in a 10 mL glass bottle for 24 hours to prepare a 100 mg / L lactalbumin solution; then 1 mL of a 180 mg / mL methyl trioctyl ammonium chloride aqueous solution was added, and the solution was shaken at 160 rpm for 30 minutes, and then 0.3 mL of a 6 mg / mL tri(2-carboxyethyl) phosphine hydrochloride solution with a pH of 7 was added (tri(2-carboxyethyl) phosphine hydrochloride was dissolved in deionized water and the pH was adjusted to 7 with a 5 mol / L sodium hydroxide aqueous solution), and the resulting mixed solution was stirred and reacted at 35° C. for 4 hours to transform the lactalbumin from a dissolved state into a phase transition aggregate encapsulating the methyl trioctyl ammonium chloride, and then the solution was centrifuged 3 times at a speed of 5000 rpm for a total of 5 minutes with deionized water at room temperature to remove the tri(2-carboxyethyl) phosphine hydrochloride, and then freeze-dried for 24 hours to obtain a dry white powdery protein-based adsorbent.

[0034] Example 5

[0035] 300 mg of lysozyme was dissolved in 3 mL of trifluoroethanol and placed in a 10 mL glass bottle for 24 hours to prepare a 100 mg / L lysozyme solution; then 1 mL of a 60 mg / mL n-octylamine aqueous solution was added to the lysozyme solution, and the solution was shaken at 160 rpm for 30 minutes, and then 0.3 mL of a 129 mg / mL tris(2-carboxyethyl)phosphine hydrochloride solution with a pH of 7 (prepared by dissolving tris(2-carboxyethyl)phosphine hydrochloride in deionized water and adjusting the pH to 7 with a 5 mol / L sodium hydroxide aqueous solution) was added, and the resulting mixed solution was stirred and reacted at 35° C. for 4 hours to transform the lysozyme from a dissolved state to a phase transition aggregate encapsulating n-octylamine, and then the solution was centrifuged 3 times at a speed of 5000 rpm at room temperature for a total of 5 minutes with deionized water to remove the tris(2-carboxyethyl)phosphine hydrochloride, and then freeze-dried for 24 hours to obtain a dry white powdery protein-based adsorbent.

[0036] Example 6

[0037] Application of the protein-based adsorbent prepared in Example 1 in the selective adsorption of metal rhenium ions

[0038] 1. Effect of pH value on the selective adsorption of metal rhenium ions by protein-based adsorbents

[0039] After 5 mL of 1 mg / mL rhenium standard solution and 5 mL of 1 mg / mL molybdenum standard solution were mixed evenly, they were diluted with deionized water to a total concentration of rhenium ions and molybdenum ions of 0.01 mg / mL. Then, the diluted solution was adjusted to pH = 1, pH = 6, pH = 10, and pH = 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution. Then, 40 mg of protein-based adsorbent was added to each 10 mL of solution, and adsorbed at 298 K for 24 hours. Figure 3 It can be seen that when pH = 12, the separation effect of rhenium ions and molybdenum ions is best.

[0040] 2. Effect of the amount of protein-based adsorbent added on the selective adsorption of metal rhenium ions

[0041] After 5 mL of 1 mg / mL rhenium standard solution and 5 mL of 1 mg / mL molybdenum standard solution were mixed evenly, they were diluted with deionized water to a total concentration of rhenium ions and molybdenum ions of 0.01 mg / mL. Then, the diluted solution was adjusted to pH = 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution. Then, 5 mg, 10 mg, 20 mg, 40 mg, 60 mg, 80 mg, and 100 mg of protein-based adsorbent were added per 10 mL of solution, respectively, and adsorbed at 298 K for 24 hours. Figure 4 , Figure 5 It can be seen that when the addition amount of protein-based adsorbent is 10 mg, the adsorption effect of rhenium ions is the best.

[0042] 3. Effect of rhenium and molybdenum concentrations on the adsorption performance of protein-based adsorbents

[0043] After 5 mL of 1 mg / mL rhenium standard solution and 5 mL of 1 mg / mL molybdenum standard solution were mixed evenly, they were diluted with deionized water to a total concentration of rhenium ions and molybdenum ions of 0.001 mg / mL, 0.01 mg / mL, 0.02 mg / mL, and 0.05 mg / mL, respectively. Then, the diluted solution was adjusted to pH = 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution, and 10 mg of protein-based adsorbent was added per 10 mL of solution, and adsorbed at 310 K for 24 hours. Figure 6 It can be seen that when the total concentration of rhenium and molybdenum is 0.01 mg / mL, the adsorption amount of rhenium ions by the protein-based adsorbent is the highest.

[0044] 4. Effect of temperature on the selective adsorption of rhenium ions by protein-based adsorbents

[0045] After 5 mL of 1 mg / mL rhenium standard solution and 5 mL of 1 mg / mL molybdenum standard solution were mixed evenly, they were diluted with deionized water to a total concentration of rhenium ions and molybdenum ions of 0.01 mg / mL. Then, the diluted solution was adjusted to pH = 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution. Then, 10 mg of protein-based adsorbent was added per 10 mL of solution, and adsorbed at 298K, 310K, and 333K for 24 hours. Figure 7 It can be seen that when the temperature is 298-333K, the protein-based adsorbent has a good adsorption effect on rhenium ions.

[0046] 5. Effect of Mo concentration on the selective adsorption of metal rhenium ions by protein-based adsorbents

[0047] 5 mL of 1 mg / mL rhenium standard solution was diluted with deionized water to a rhenium ion concentration of 0.001 mg / mL, and 5 mL of 1 mg / mL molybdenum standard solution was diluted with deionized water to molybdenum ion concentrations of 0.001 mg / mL, 0.1 mg / mL, 0.2 mg / mL, 0.5 mg / mL, 0.8 mg / mL, and 1 mg / mL, respectively; then 5 mL of the diluted rhenium standard solution was mixed evenly with 5 mL of molybdenum standard solution diluted to different molybdenum ion concentrations to obtain solutions with a mass ratio of rhenium ion to molybdenum ion of 1:1, 1:100, 1:200, 1:500, 1:800, and 1:1000, respectively, and the solution was adjusted to pH = 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution, and then 10 mg of protein-based adsorbent was added per 10 mL of solution, and adsorbed at 310K for 24 hours. Figure 8It can be seen that the adsorption rate of rhenium ions by the protein-based adsorbent is about 90%, while the adsorption rate of molybdenum ions only increases from 5% at 0.001 mg / mL to 15% at 1 mg / mL.

[0048] 6. Practical Application

[0049] Industrial wastewater containing molybdenum ions and rhenium ions was diluted with deionized water by 0, 100, 500, 1000, 2000, 5000, and 10000 times, and the pH was adjusted to 12 with 10 mg / mL HNO3 aqueous solution and 5 mol / L NaOH aqueous solution, and then 10 mg of protein-based adsorbent was added per 10 mL, and adsorbed at 310 K for 24 hours. Fig. 9 It can be seen that after the rhenium ion was diluted from 0 to 1000 times in industrial wastewater, the adsorption rate of the protein-based adsorbent increased from 83% to 95%, and after the dilution multiple was greater than 1000, the adsorption rate was close to 100%, while the adsorption rate of molybdenum ion gradually decreased from 20% to 10% when it was diluted from 0 to 1000 times, and further reached less than 5% after dilution of 1000 times; Fig.10 It can be seen that the adsorption rate of rhenium ions by protein-based adsorbents is significantly higher than that of other metal ions, especially molybdenum ions.

[0050] 1 mg / mL rhenium standard solution and 1 mg / mL molybdenum standard solution were mixed uniformly at a volume ratio of 1:1 to obtain a rhenium and molybdenum standard solution. 10 mg of the protein-based adsorbent of Example 1 was directly put into 10 mL of the rhenium and molybdenum standard solution for adsorption. The maximum amount of rhenium adsorbed per gram of adsorbent was 124 mg / g, and the separation coefficient (β) of the metal rhenium ion was 1. Re / Mo ) is 2.78×10 3 The adsorption capacity per unit area is 57.2 mg g -1 ·m -2 .

Claims

1. A protein-based adsorbent for selectively adsorbing metallic rhenium ions, characterized in that: The protein-based adsorbent is obtained by encapsulating alkylamine or ammonium salt in the process of reducing protein to form phase transition aggregates by a reducing agent. The preparation method is as follows: dissolving the protein in trifluoroethanol, standing for more than 24 hours, then adding the alkylamine or ammonium salt, mixing evenly, then adding the reducing agent solution, stirring the obtained mixed solution at 30-40° C. until the protein changes from a dissolved state to a phase transition aggregate encapsulating the alkylamine or ammonium salt, washing with deionized water by centrifugation, and freeze-drying to obtain the protein-based adsorbent; The alkylamine is any one of di-n-octylamine, n-octylamine, and tri-isooctylamine, and the ammonium salt is any one of trimethyltrioctylammonium chloride, octyltrimethylammonium chloride, and dodecyltrimethylammonium chloride; The protein is any one of lysozyme, lactalbumin, insulin, bovine serum albumin, thyrolactoglobulin, lactoferrin, fibrinogen, collagen, keratin, β-lactoglobulin, and myoglobin; The reducing agent is any one of tris(2-carboxyethyl)phosphine hydrochloride, cysteine, and glutathione; The reducing agent concentration in the mixed solution is 0.1-20 mg / mL, the protein concentration is 30-140 mg / mL, and the alkylamine or ammonium salt concentration is 5-80 mg / mL.

2. The protein-based adsorbent for selectively adsorbing metallic rhenium ions according to claim 1, characterized in that: The reducing agent concentration in the mixed solution is 0.4-10 mg / mL, the protein concentration is 50-80 mg / mL, and the alkylamine or ammonium salt concentration is 10-50 mg / mL.

3. The protein-based adsorbent for selectively adsorbing metallic rhenium ions according to claim 1, characterized in that: The reducing agent solution is prepared by adding a reducing agent into water and adjusting the pH value to 7 with NaOH.

4. The use of the protein-based adsorbent according to claim 1 in the selective adsorption of metal rhenium ions, characterized in that: The metal rhenium ions are derived from any one of copper ore smelting smoke and waste slag, platinum group ore smelting smoke and waste slag, niobium ore smelting smoke and waste slag, zinc ore smelting smoke and waste slag, and low-grade molybdenum ore waste liquid.

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