High-adsorption-capacity precious metal adsorbent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of precious metal recovery, and particularly relates to a high-adsorption-capacity precious metal adsorbent and a preparation method and application thereof. The invention provides a high-adsorption-capacity precious metal adsorbent. The high-adsorption-capacity precious metal adsorbent is prepared by crosslinking polyethyleneimine and carbon disulfide, the high-adsorption-capacity precious metal adsorbent is insoluble in water and has a porous structure. The adsorbent disclosed by the invention has relatively high adsorption capacity on trivalent gold ions and divalent palladium ions at the same time; meanwhile, the adsorbent has excellent adsorption selectivity on trivalent gold ions and divalent palladium ions. The adsorbent disclosed by the invention can be recycled after desorption, and is a saving type material; and the preparation method is simple, mild in synthesis condition, low in raw material cost and easy to industrialize.

Description

Technical Field

[0001] The present invention belongs to the technical field of precious metal recovery, and particularly relates to a precious metal adsorbent with a high adsorption capacity, a preparation method thereof, and an application thereof. Background Art

[0002] Precious metal resources are scarce and non-renewable, while the content of precious metals in secondary resources is often higher than that in primary ores. The gold content in one ton of waste smartphones can reach 280 grams, which is 60 times that of the original ore. Electronic waste contains rich precious metal resources. By recycling, it can turn waste into treasure and open up the "second mine"; moreover, the recycling of precious metal secondary resources can reduce the emission of waste and avoid environmental pollution. For example, recovering precious metals from secondary resources such as electronic waste and waste catalysts can effectively reduce the potential harm of these wastes to the environment.

[0003] Currently, there are many methods for recovering precious metals from electronic waste or waste catalysts, such as solvent extraction, ion exchange, chemical precipitation, adsorption, etc. Adsorption is considered the most reliable method for extracting metal ions, and organic polymers are considered an optimal candidate adsorbent, with characteristics such as diverse structures and easy modification. Functionalized organic polymers can introduce specific functional groups to enhance the adsorption capacity for target pollutants. For example, nitrogen-containing group-functionalized organic polymers and oxygen-containing group-functionalized organic polymers. However, when using the current functionalized organic polymers as precious metal adsorbents, there is still a problem of low adsorption capacity for precious metals. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a precious metal adsorbent with a high adsorption capacity, a preparation method thereof, and an application thereof. The precious metal adsorbent of the present invention has a high adsorption capacity for precious metals.

[0005] The present invention provides a precious metal adsorbent with a high adsorption capacity, which is cross-linked by polyethyleneimine and carbon disulfide; the precious metal adsorbent with a high adsorption capacity is insoluble in water and has a porous structure.

[0006] Preferably, the molar ratio of carbon disulfide to amino groups in polyethyleneimine is 10:1.

[0007] Preferably, the adsorption capacity of the precious metal adsorbent with a high adsorption capacity for gold is 0.1 - 6 g / g, and the adsorption capacity for palladium is 0.1 - 2 g / g.

[0008] The present invention also provides a preparation method of the precious metal adsorbent with a high adsorption capacity as described in the above technical solution, including the following steps:

[0009] Mix polyethyleneimine, carbon disulfide, and a polar organic solvent for cross-linking reaction to obtain the precious metal adsorbent with a high adsorption capacity.

[0010] Preferably, the temperature of the cross-linking reaction is 40 to 60 °C, and the time is 4 to 6 h.

[0011] Preferably, the polar organic solvent is N,N-dimethylformamide.

[0012] Preferably, the mixing of polyethyleneimine, carbon disulfide and polar organic solvent is as follows: first dissolve polyethyleneimine in the polar organic solvent to obtain a polyethyleneimine solution, and then dropwise add carbon disulfide.

[0013] The present invention also provides the application of the high-adsorption-capacity noble metal adsorbent described in the above technical solution or the high-adsorption-capacity noble metal adsorbent obtained by the above preparation method in noble metal recovery, and the noble metals include gold and / or palladium.

[0014] The present invention also provides a method for recovering noble metals, comprising the following steps:

[0015] Mix the noble metal-containing system and the adsorbent for adsorption to obtain an adsorbent adsorbed with noble metals; the noble metals include gold and / or palladium; the adsorbent is the high-adsorption-capacity noble metal adsorbent described in the above technical solution or the high-adsorption-capacity noble metal adsorbent obtained by the above preparation method;

[0016] Mix the adsorbent adsorbed with noble metals with an acidic thiourea solution for desorption to obtain a recovered adsorbent and noble metals respectively.

[0017] Preferably, the temperature of the adsorption is 5 to 50 °C.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a high-adsorption-capacity noble metal adsorbent, which is cross-linked by polyethyleneimine and carbon disulfide; the high-adsorption-capacity noble metal adsorbent is insoluble in water and has a porous structure.

[0020] For the adsorbent of the present invention, polyethyleneimine and carbon disulfide cross-link to form a thioamide group -NH-C(=S)-NH-, and the sulfur (S) and nitrogen (N) therein act as electron donors, which can form a stable chelate structure with soft-acid metal ions Au(III) and Pd(II), improving the maximum equilibrium adsorption capacity and adsorption selectivity for Au(III) and Pd(II). Under the condition of the existence of other potential interfering ions, the high-efficiency adsorption rate for Au(III) and Pd(II) can still be maintained. Moreover, cross-linking expands the molecular chain of polyethyleneimine to form a porous structure, and the water-soluble polyethyleneimine becomes a water-insoluble and acid- and alkali-resistant white solid powder material, which can be directly used as a noble metal adsorbent, and the water-insoluble property makes the cross-linked polyethyleneimine easier to recycle.

[0021] The present invention also provides a method for preparing a precious metal adsorbent with a high adsorption capacity, which has mild synthesis conditions, a simple method, low raw material costs, and is easy to industrialize.

[0022] The present invention also provides a method for recovering precious metals. The adsorbent of the present invention has a large adsorption capacity for both trivalent gold ions and divalent palladium ions; and has excellent adsorption selectivity for both trivalent gold ions and divalent palladium ions. The adsorbent of the present invention can be recycled after desorption, is a kind of material that saves resources, can reduce waste pollution, and brings higher economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic diagram of the recovery of gold or palladium by the adsorbent of the present invention;

[0025] Figure 2 It is a graph of the adsorption rate results in the simulated gold-palladium coexisting solution in Application Example 7 when containing different proportions of impurity ions;

[0026] Figure 3 It is the recovery rate result after dissolving electronic waste with aqua regia in Application Example 8;

[0027] Figure 4 It is the recovery rate result after dissolving waste palladium catalyst with aqua regia in Application Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention provides a precious metal adsorbent with a high adsorption capacity, which is cross-linked by polyethyleneimine and carbon disulfide; the precious metal adsorbent with a high adsorption capacity is insoluble in water and has a porous structure.

[0029] In the present invention, the molar ratio of the carbon-sulfur double bond in carbon disulfide to the amino group in polyethyleneimine is preferably 10:1.

[0030] In the present invention, the adsorption capacity of the precious metal adsorbent with a high adsorption capacity for gold is preferably 0.1 - 6 g / g (the amount of gold adsorbed per g of adsorbent is 0.1 - 6 g), and the adsorption capacity for palladium is preferably 0.1 - 2 g / g (the amount of palladium adsorbed per g of adsorbent is 0.1 - 2 g).

[0031] The present invention also provides a method for preparing the precious metal adsorbent with a high adsorption capacity described in the above technical solution, including the following steps:

[0032] Mix polyethyleneimine, carbon disulfide, and a polar organic solvent for a cross-linking reaction to obtain the high-adsorption-capacity noble metal adsorbent.

[0033] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0034] In the present invention, the weight-average molecular weight of the polyethyleneimine (PEI) is preferably 10,000, the manufacturer is Shanghai Titan Technology Co., Ltd., the purity is 99%, and the structural formula is as follows. Each molecule of polyethyleneimine contains 80 amino groups.

[0035]

[0036] In the present invention, the molar ratio of carbon disulfide to the amino groups in polyethyleneimine is preferably 10:1, and the carbon disulfide is a cross-linking agent. The molar ratio described in the present invention results in a high adsorption capacity of the cross-linked polyethyleneimine for noble metals.

[0037] In the present invention, the polar organic solvent is preferably N,N-dimethylformamide.

[0038] In the present invention, the temperature of the cross-linking reaction is preferably 40 - 60 °C, specifically it can be 40 °C, 50 °C, or 60 °C, and the time is preferably 4 - 6 h, specifically it can be 4 h, 5 h, or 6 h. The cross-linking reaction temperature and time described in the present invention result in a high adsorption capacity of the noble metal adsorbent for noble metals.

[0039] In the present invention, the cross-linking reaction is preferably carried out under stirring, and the stirring speed is preferably 200 - 500 r / min, more preferably 300 r / min. The reaction formula of the cross-linking reaction is as follows (showing a partial amino group reaction):

[0040]

[0041] In the formula, the connection site (-NH end, wavy line) indicates connection to the PEI main body. During the cross-linking reaction (nucleophilic substitution reaction), the carbon-sulfur double bond cross-links with the amino group, the polyethyleneimine molecular chain expands, forming a porous structure, making the water-soluble polyethyleneimine become a water-insoluble and acid- and alkali-resistant solid powder material, which can be directly used as an adsorbent; at the same time, the functionalized atom S on the cross-linking agent carbon disulfide further increases the adsorption sites and adsorption capacity of the adsorbent, improving the adsorption effect of the adsorbent.

[0042] In the present invention, the mixing of polyethyleneimine, carbon disulfide and polar organic solvent is preferably as follows: first dissolve polyethyleneimine in polar organic solvent to obtain a polyethyleneimine solution, and then dropwise add carbon disulfide. The dropping rate is preferably 1 drop / s. After dissolving polyethyleneimine first in the present invention, it can effectively crosslink with carbon disulfide, thereby enhancing the yield of the adsorbent and improving the adsorption effect of the adsorbent.

[0043] In the present invention, after the crosslinking reaction, it preferably further includes: solid-liquid separation, and the obtained solid is subjected to impurity removal and drying. The solid-liquid separation method is preferably filtration. The impurity removal preferably includes: mixing the obtained solid with ethanol for vacuum distillation, and then mixing the obtained solid with water for vacuum distillation. The impurity removal includes removing unreacted carbon disulfide. The drying is preferably vacuum freeze-drying, preferably drying to constant weight, and the specific time can be 24 h. The impurity removal and drying in the present invention can remove impurities and moisture in the adsorbent, thereby improving the thermal stability and chemical stability of the adsorbent, and enabling it to maintain good adsorption performance under different environmental conditions.

[0044] The present invention also provides the application of the high-adsorption-capacity noble metal adsorbent described in the above technical solution or the high-adsorption-capacity noble metal adsorbent obtained by the above preparation method in noble metal recovery; the noble metal includes gold and / or palladium.

[0045] The present invention also provides a method for recovering noble metals, comprising the following steps:

[0046] Mix a noble metal-containing system and an adsorbent for adsorption to obtain an adsorbent adsorbed with noble metals; the noble metal includes gold and / or palladium; the adsorbent is the high-adsorption-capacity noble metal adsorbent described in the above technical solution or the high-adsorption-capacity noble metal adsorbent obtained by the above preparation method;

[0047] Mix the adsorbent adsorbed with noble metals with an acidic thiourea solution for desorption to obtain a recovered adsorbent and noble metals respectively.

[0048] In the present invention, the adsorption temperature is preferably 5-50 °C, and specifically can be 5 °C, 15 °C, 25 °C, 30 °C, 35 °C or 45 °C. The adsorption is preferably carried out in a constant temperature water bath shaker.

[0049] In the present invention, the mass ratio of gold to the adsorbent is preferably 0.1 - 6:1, and the mass ratio of palladium to the adsorbent is preferably 0.1 - 2:1. The dosage ratio of the noble metal-containing system to the adsorbent is preferably 20 mL:5 mg or 100 mL:50 mg. The noble metal-containing system preferably includes an aqueous solution containing trivalent gold ions and / or divalent palladium ions. The concentration of the aqueous solution containing trivalent gold ions is preferably 10 - 1500 mg / L, and the pH value is preferably 1 - 13, more preferably 1 - 10, specifically 1, 2, 3, 4, 5, 6, or 7; the concentration of the aqueous solution containing divalent palladium ions is preferably 10 - 1000 mg / L, and the pH value is preferably 1 - 6, more preferably 1 - 5, specifically 1, 2, 3, 4, or 5.

[0050] In the present invention, the adsorption time is preferably 5 min - 72 h, specifically 5 min, 10 min, 12 h, 24 h, or 72 h.

[0051] In the present invention, after adsorption, solid-liquid separation is preferably further included. The solid-liquid separation is preferably filtration, and the filtration preferably uses a 0.22 μm microporous membrane.

[0052] In the present invention, the concentration of HCl in the acidic thiourea solution is preferably 0.1 - 1 mol / L, more preferably 0.5 mol / L, and the concentration of thiourea is preferably 0.1 - 1 mol / L, more preferably 0.5 mol / L.

[0053] In the present invention, the desorption time is preferably 8 - 14 h, more preferably 12 h.

[0054] The noble metal adsorbent of the present invention has a large adsorption capacity for noble metals, good selectivity, and good reusability.

[0055] To further illustrate the present invention, the high-adsorption-capacity noble metal adsorbent provided by the present invention, its preparation method, and its application will be described in detail below in conjunction with the drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

[0056] In the examples of the present invention, the polyethyleneimine used is from Shanghai Titan Scientific Co., Ltd., with a weight-average molecular weight of 10,000, and each polyethyleneimine molecule contains 80 amino groups.

[0057] Example 1

[0058] Use a pipette to take 200 mL of N,N-dimethylformamide and put it into a three-necked flask (equipped with a condenser) containing 6 g of polyethyleneimine (containing 48 mmol of amino groups), and ultrasonically dissolve the polyethyleneimine. Slowly add carbon disulfide dropwise (1 drop per second, a total of 28.9 mL) to the above three-necked flask using a constant-pressure dropping funnel. At a temperature of 50 °C, stir with a magnetic stirrer for 5 h at a stirring speed of 300 r / min, and solid substances appear in the three-necked flask.

[0059] Filter out the solid in the three-necked flask, wash the filter cake by suction filtration with N,N-dimethylformamide, mix the obtained solid with ethanol and perform vacuum distillation, then mix the obtained solid with ultrapure water and perform vacuum distillation. Dry the solid substance after removing impurities in a vacuum freeze dryer until it reaches a constant weight. The dried solid substance is the adsorbent (CS2PEI).

[0060] Next, use the adsorbent prepared in Example 1 to adsorb gold and palladium:

[0061] Application Example 1

[0062] Prepare an aqueous solution of trivalent gold ions with a concentration of 619.25 mg / L and adjust the pH value to 1 to 13. Prepare an aqueous solution of divalent palladium ions with a concentration of 221.98 mg / L and adjust the pH value to 1 to 5. Respectively transfer 20 mL of the aqueous solution of trivalent gold ions into 13 centrifuge tubes with a capacity of 50 mL; respectively transfer 20 mL of the aqueous solution of divalent palladium ions into 5 centrifuge tubes with a capacity of 50 mL; add 5 mg of the adsorbent from Example 1 to all centrifuge tubes, seal the tube mouths, and place them in a constant-temperature water bath shaker at 25 °C for oscillating adsorption for 24 h. After the adsorption is completed, filter the samples, dilute the filtrate, and analyze it using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer. The results are shown in Table 1:

[0063] Table 1 Effects of different pH values on the adsorption of gold and palladium

[0064] pH value Gold adsorption capacity, mg / g Palladium adsorption capacity, mg / g 1 2164.26 806.52 2 2240.38 772.19 3 2313.97 749.99 4 2350.70 640.07 5 2400.19 568.45 6 2467.66 / 7 2423.50 / 8 1831.57 / 9 1577.89 / 10 1251.82 /

[0065] The results show that gold has good adsorption within pH = 1.0 - 7.0, the adsorption rate is above 92.54%, up to 97.94%, and the adsorption capacity is above 2164.26 mg / g; the adsorption capacity of palladium at pH = 1.0 is 806 mg / g.

[0066] Application Example 2

[0067] Prepare a trivalent gold ion solution with a concentration of 9.62 mg / L and adjust the pH value to 6, and prepare a divalent palladium ion solution with a concentration of 12.22 mg / L and adjust the pH value to 1. Measure 20 mL and add it to several 50-mL centrifuge tubes. Add 5 mg of adsorbent to the centrifuge tubes, and place them in a constant temperature water bath shaker at 25 °C for oscillating adsorption. Take samples at regular intervals, filter and dilute the samples, and analyze them using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer.

[0068] The results show that: as time increases, the adsorption capacity continuously increases. Under 9.62 ppm Au(III), the adsorption of gold reaches equilibrium at 40 min, and the adsorption rate is 92% at this time. Under 12.22 ppm Pd(II), it can reach 83.57% in 1 min, and the adsorption of palladium basically reaches equilibrium at 10 min, and the adsorption rate is 99% at this time. Subsequently, the adsorption rate reaches 100%. At low concentrations, the adsorption rate of CS2@PEI for Pd(II) can quickly reach 99%.

[0069] Application Example 3

[0070] Prepare a trivalent gold ion solution with a concentration of 505.87 mg / L and adjust the pH value to 6, and prepare a divalent palladium ion solution with a concentration of 198.55 mg / L and adjust the pH value to 1. Measure 20 mL of each aqueous solution and add it to several 50-mL centrifuge tubes. Add 5 mg of adsorbent to the centrifuge tubes, and place them in a constant temperature water bath shaker at 25 °C for oscillating adsorption. Take samples at regular intervals, filter and dilute the samples, and analyze them using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer.

[0071] The results show that: as time increases, the adsorption capacity continuously increases. The adsorption of gold basically reaches equilibrium at 16 h, and the adsorption rate is 99%; the adsorption of palladium reaches equilibrium at 6 h, and the adsorption rate is 83% at this time.

[0072] Application Example 4

[0073] Prepare multiple trivalent gold ion solutions with concentrations ranging from 52 mg / L to 1979 mg / L, adjust the pH value of the solutions to 6, and prepare multiple divalent palladium ion solutions with concentrations ranging from 10 mg / L to 626 mg / L, adjust the pH value of the solutions to 1. Transfer 20 mL of all the prepared solutions into 50-mL centrifuge tubes respectively. After adding 5 mg of adsorbent to all the centrifuge tubes, seal their tube mouths, and place the centrifuge tubes in a constant temperature water bath shaker at 25 °C for oscillating adsorption for 72 h. After the adsorption is completed, filter the samples, take the filtrate and dilute it, and analyze it using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer.

[0074] The results show that: with the increase of the initial concentration, the adsorption capacity also increases. The maximum adsorption equilibrium value of Au(III) can reach 5999 mg / g, and the maximum adsorption equilibrium value of Pd(II) can reach 1041 mg / g. When the concentration of Au(III) is less than 1256.96 mg / L and the concentration of Pd(II) is less than 158.90 mg / L, the adsorption rate of CS2@PEI can reach more than 90%.

[0075] Application Example 5

[0076] Prepare a gold(III) ion solution with a concentration of 1378 mg / L and adjust the pH value of the solution to 6, and prepare an aqueous palladium(II) ion solution with a concentration of 308 mg / L and adjust the pH value of the solution to 1. Transfer 20 mL of the prepared solutions into centrifuge tubes with a capacity of 50 mL respectively, add 5 mg of the adsorbent to the centrifuge tubes, and place the centrifuge tubes in a constant temperature water bath shaker at 5, 15, 25, and 35 °C for oscillating adsorption for 72 h. After the adsorption is completed, filter the samples, dilute the filtrate, and analyze it using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer. The results are shown in Table 2:

[0077] Table 2 Influence of adsorption temperature on the adsorption of gold and palladium

[0078] Temperature, °C Gold adsorption capacity, mg / g Palladium adsorption capacity, mg / g 5 2134.41 654.61 15 3432.86 725.71 25 4185.65 767.06 35 4724.42 805.80

[0079] The results show that: for gold(III) ions and palladium(II) ions, with the increase of temperature, the adsorption capacity increases.

[0080] Application Example 6

[0081] Prepare a gold(III) ion solution with a concentration of 108 mg / L and adjust the pH value of the solution to 6. Measure 100 mL and place it in a 250 mL conical flask. Add 50 mg of the adsorbent to the conical flask, and place the conical flask in a constant temperature water bath shaker at 25 °C for oscillating adsorption for 12 h. After the adsorption is completed, filter the samples, dilute the filtrate, and analyze it using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer.

[0082] Filter the adsorbent after adsorption by suction filtration and wash it three times with water. Put the washed adsorbent after adsorption into 100 mL of acidic thiourea solution (HCl concentration 0.5 mol / L, thiourea concentration 0.5 mol / L) for desorption for 12 h. After the desorption is completed, filter the supernatant, dilute the filtrate, and analyze it using an atomic absorption spectrophotometer and an Agilent 7800 inductively coupled plasma mass spectrometer. Filter the desorbed adsorbent by suction filtration, wash it 3 times with deionized water, and obtain the first recycled sample. Repeat for multiple cycles.

[0083] The results show that after 4 times of repeated use, the gold adsorption rate decreases from 99.83% to 83%.

[0084] The recycling experiment of divalent palladium ions was the same as above. After being reused 10 times, the adsorption rate remained at 99.9%, indicating that the adsorbent could be recycled multiple times.

[0085] Application Example 7

[0086] Examine the adsorption rates of CS2PEI under different coexistence ratios of Au(III), Pd(II) and base metals:

[0087] Since the leaching solution obtained by leaching waste secondary resources with aqua regia is acidic, the pH value of the simulated solution is 1. The simulated solution system includes Au(III) and Pd(II), as well as various coexisting impurity ions, including Cu, Zn, Co, Cd, Pb, Fe, Ni.

[0088] The concentrations of Au(III) and Pd(II) are both 0.1 mmol / L. The adsorption rate results when the molar ratio of Au(III) (or Pd(II)) to each other metal ion in the simulated solution system is 1:10 and 1:100 are shown in Table 3:

[0089] Table 3 Adsorption rate results when the molar ratio of Au(III) (or Pd(II)) to each other metal ion is 1:10 and 1:100

[0090] Adsorption rate (%) at molar ratio of 1:10 Adsorption rate (%) at molar ratio of 1:100 Au 98.04 96.98 Pd 93.19 93.75 Cu 2.30 2.92 Co 2.54 0 Pb 2.85 0.64 Fe 0 0.030 Ni 0.80 0.40 Zn 0 0 Cd 0 0.34

[0091] It can be seen that the adsorbent CS2PEI of the present invention shows high selectivity for Au(III) and Pd(II), the adsorption rate for Au(III) is greater than 96%, the adsorption rate for Pd(II) is greater than 93%, while the adsorption rates for other impurity ions are all lower than 3%.

[0092] Figure 1 This is a schematic diagram of the recovery of gold or palladium by the adsorbent of the present invention. The PEI-based adsorbent prepared by the present invention can selectively adsorb gold or palladium.

[0093] Figure 2 This is a graph of the adsorption rate results in the simulated gold-palladium coexisting solution in Application Example 7, with different proportions of impurity ions.

[0094] Application Example 8

[0095] Dissolve a piece of waste PCBs circuit board in 80 mL of aqua regia, filter after dissolving for 24 hours, dilute it 10 times with distilled water, adjust the pH value of the solution to 1, and add 5 mg of the adsorbent to 20 mL of the leaching solution. The results are as Figure 3(The small figures therein represent the concentrations of various ions in the leachate). As shown in Table 4, the CS2@PEI adsorbent achieved an adsorption rate of 93.46% for Au(III) in the leachate, while the adsorption rates for other metal ions were less than 1%.

[0096] Similarly, the adsorption effect on Pd(II) in practice was evaluated. After dissolving 20 g of waste palladium catalyst in 40 mL of aqua regia for 24 hours, it was filtered and diluted 5 times with distilled water. The results are as Figure 4 (The small figures therein represent the concentrations of various ions in the leachate). As shown in Table 4, CS2@PEI achieved an adsorption effect of 98.79% for Pd(II) in the leachate.

[0097] Table 4 Results of precious metal recovery from e-waste and waste palladium catalyst

[0098] Recovery rate of waste PCBs (%) Recovery rate of waste catalyst (%) Au 93.46 - Pd 98.79 Cu 0.27 0 Zn 0 11.34 Fe 0 0 Ni 0 0 Mg 0 0 Mn 0.92 0

[0099] The results show that CS2@PEI has significant practicality and selectivity for the recovery of Au(III) and Pd(II) in aqua regia leachate.

[0100] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments according to the embodiments of the present invention without creative labor, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A noble metal adsorbent with a high adsorption capacity, characterized in that, It is cross-linked by polyethyleneimine and carbon disulfide; the high-adsorption-capacity noble metal adsorbent is insoluble in water and has a porous structure.

2. The high-adsorption-capacity noble metal adsorbent according to claim 1, wherein The molar ratio of carbon disulfide to amino groups in polyethyleneimine is 10:

1.

3. The high-adsorption-capacity noble metal adsorbent according to claim 1 or 2, characterized in that, The adsorption capacity of the high-adsorption-capacity noble metal adsorbent for gold is 0.1 - 6 g / g, and the adsorption capacity for palladium is 0.1 - 2 g / g.

4. The preparation method of the high-adsorption-capacity noble metal adsorbent according to any one of claims 1 to 3, characterized in that, It includes the following steps: Mix polyethyleneimine, carbon disulfide and a polar organic solvent for cross-linking reaction to obtain the high-adsorption-capacity noble metal adsorbent.

5. The preparation method according to claim 4, characterized in that, The temperature of the cross-linking reaction is 40 - 60 °C, and the time is 4 - 6 h.

6. The preparation method according to claim 4, characterized in that, The polar organic solvent is N,N-dimethylformamide.

7. The preparation method according to claim 4, characterized in that, The mixing of polyethyleneimine, carbon disulfide and the polar organic solvent is as follows: first dissolve polyethyleneimine in the polar organic solvent to obtain a polyethyleneimine solution, and then dropwise add carbon disulfide.

8. Application of the high-adsorption-capacity noble metal adsorbent according to any one of claims 1 - 3 or the high-adsorption-capacity noble metal adsorbent obtained by the preparation method according to any one of claims 4 - 7 in noble metal recovery, wherein the noble metal includes gold and / or palladium.

9. A method for recovering a precious metal, characterized in that, It includes the following steps: Mix the noble metal-containing system and the adsorbent for adsorption to obtain the adsorbent adsorbed with noble metal; the noble metal includes gold and / or palladium; the adsorbent is the high-adsorption-capacity noble metal adsorbent according to any one of claims 1 - 3 or the high-adsorption-capacity noble metal adsorbent obtained by the preparation method according to any one of claims 4 - 7; Mix the adsorbent adsorbed with noble metal with an acidic thiourea solution for desorption to obtain the recovered adsorbent and noble metal respectively.

10. According to the recovery method of claim 9, the temperature of the adsorption is 5 - 50 °C.

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