CN102019167A - Functionalized mesoporous molecular sieve and application of functionalized mesoporous molecular sieve in recovering noble metal - Google Patents

Abstract

The invention discloses a functionalized mesoporous molecular sieve and its application in precious metal recovery. The functionalized mesoporous molecular sieve is a silicon-based mesoporous molecular sieve grafted with amino groups or mercapto groups, and its application in recovering precious metals from waste electronic circuit boards includes the following steps: processing waste electronic circuit boards to obtain a metal solution, First adjust the pH value of the metal solution to about 1, and use functionalized mesoporous molecular sieves to selectively adsorb palladium ions and/or platinum ions; then adjust the pH value of the metal solution to about 2.5, and use functional molecular sieves to selectively adsorb them gold; wash the molecular sieves loaded with palladium ions and/or platinum ions and gold-loaded molecular sieves with 3-6M hydrochloric acid, respectively, so that the precious metals can be desorbed into the solution, and the molecular sieves can be reactivated at the same time. The method for recovering precious metals in the present invention has simple process, high adsorption rate of precious metals and environmental protection advantages.

Description

A functionalized mesoporous molecular sieve and its application in recovery of precious metals

1. Technical field:

The invention specifically relates to a mesoporous molecular sieve grafted with functional group amino or mercapto and its application in recovering precious metals such as gold, palladium, platinum and the like from waste electronic circuit boards. the

3. Background technology:

According to relevant statistical data, the discarded electronic circuit boards contain quite high metals, generally 20-40%, especially precious metals, which are dozens or even hundreds of times that of natural mineral deposits. It contains 3-8% gold, 0.1-1% platinum and palladium, and of course copper, tin, aluminum, nickel, lead and other metals with varying contents. Judging from the content of precious metals such as gold, platinum and palladium, the recovery of precious metals from waste electronic circuit boards has great economic benefits. The key to the recovery is how to separate and enrich precious metals from other metals. the

Common molecular sieves (such as SBA-15, MCM-41) are new nano-functional materials with ordered mesoporous structures. The BET specific surface area can generally reach about 1000m ² /g. These characteristics make mesoporous molecular sieves have good application prospects in the fields of macromolecule adsorption, catalytic reaction, and drug delivery. However, these molecular sieves have no adsorption effect on noble metal ions in aqueous solution.

Therefore, it is meaningful to design a molecular sieve that can selectively adsorb noble metal ions in aqueous solution to achieve the separation and enrichment of noble metals from common metals. the

3. Contents of the invention:

The primary technical problem to be solved by the present invention is to provide a functionalized mesoporous molecular sieve capable of highly selectively adsorbing precious metals. the

In view of the above-mentioned technical problems, the research idea of the present invention is: make full use of the advantages of the large specific surface area of mesoporous molecular sieves such as SBA-15 and MCM-41, and graft some functional groups (such as -NH ₂ or -SH), thus having the function of selectively adsorbing noble metals.

The present invention specifically adopts the following technical solutions:

A functionalized mesoporous molecular sieve, prepared by the following method: placing a silicon-based mesoporous molecular sieve in anhydrous toluene containing 0.1-0.5 mol/L aminopropane or propanethiol at 100-120°C for 12-24 hours under reflux , and then filtered and dried at a temperature of 150-180° C. to evaporate toluene to obtain amine- or mercapto-functionalized mesoporous molecular sieves. the

The silicon-based mesoporous molecular sieve is preferably SBA-15 or MCM-41 mesoporous molecular sieve, more preferably MCM-41 mesoporous molecular sieve. the

The functionalized mesoporous molecular sieve prepared by the present invention can highly selectively adsorb gold ions, platinum ions and palladium ions under acidic conditions, and the adsorption capacity of the amino functionalized mesoporous molecular sieve is higher than that of the sulfhydryl functionalized mesoporous molecular sieve Be better. the

The second technical problem to be solved by the present invention is to apply the functionalized mesoporous molecular sieve to recover precious metals such as gold, platinum and palladium from waste electronic circuit boards. the

In view of the above-mentioned technical problems, the research idea of the present invention is: utilize mesoporous molecular sieve grafted with functional groups (such as _-NH2 or -SH) capable of adsorbing noble metal ions to selectively adsorb noble metal ions in acidic solution, under certain conditions The characteristics of not adsorbing other metal ions can effectively separate noble metal ions from common metal ions; at the same time, by adjusting the pH value of the solution, the noble metal ions adsorbed on the molecular sieve can be desorbed to achieve the enrichment of noble metal ions and the reactivation of molecular sieves. .

The technical scheme of recovering precious metals such as gold, platinum and palladium from waste electronic circuit boards of the present invention is specifically as follows:

Described recovery method comprises the steps:

(a) Pulverizing and separating the waste electronic circuit board to obtain non-metallic powder and metal powder, dissolving the metal powder with strong acid, and containing one or both of platinum ions and palladium ions and gold ions in the metal solution obtained;

(b) adjust the pH value of the metal solution to about 1, put the functionalized mesoporous molecular sieve into the metal solution, stir at room temperature for 8 to 12 hours, and filter to obtain the corresponding platinum ion and/or palladium ion Molecular sieve and filtrate A; the functionalized mesoporous molecular sieve prepared by the application has a pH of about 1, and can highly selectively adsorb platinum ions and palladium ions, while gold ions and other metal ions continue to remain in filtrate A, so According to the different components of noble metal ions in the metal solution, corresponding molecular sieves loaded with platinum ions or palladium ions or platinum ions and palladium ions are obtained. the

(c) wash the molecular sieve loaded with platinum ions and/or palladium ions with 3-6M hydrochloric acid (preferably 5M hydrochloric acid), filter to obtain platinum chloride and/or palladium chloride solution and reactivated functionalized mesoporous molecular sieve;

(d) Adjust the pH value of the filtrate A to about 2.5, put the functionalized mesoporous molecular sieve into the filtrate A, stir at room temperature for 8-12 hours, filter to obtain the gold-loaded molecular sieve, and use 3-6M hydrochloric acid (preferably 5M hydrochloric acid) The gold-loaded molecular sieve is cleaned, and the gold chloride solution and the reactivated functionalized mesoporous molecular sieve are obtained by filtering. The functionalized mesoporous molecular sieve prepared by the invention can selectively adsorb gold ions when the pH value is about 2.5, while other metal ions remain in the filtrate, thereby realizing the separation of noble metal ions from other common ions. the

In the above recovery method, after the waste electronic circuit board is crushed, it can be pulverized by an ultra-fine pulverizer, and then separated by a high-voltage electrostatic separator to obtain non-metallic powder mainly composed of glass fiber and resin and copper, tin, lead, Gold, platinum, palladium (for platinum and palladium, some electronic circuit boards may only contain platinum or only palladium) and other metal powders. the

In the above solution for recovering precious metals, the strong acid described in step (a) is used to dissolve the metal powder, preferably a mixed acid of concentrated nitric acid and concentrated hydrochloric acid or aqua regia with a volume ratio of 2:1. Common lyes such as sodium hydroxide solution can be used to adjust the pH value in step (b) and step (d). Molecular sieves and gold-loaded molecular sieves loaded with platinum ions and/or palladium ions are treated with 3-6M hydrochloric acid solution, preferably 5M hydrochloric acid solution, so that the precious metals adsorbed on the molecular sieves can be desorbed and enter the solution, while the molecular sieves are reactivated ,reusable. As for the palladium chloride solution obtained, the platinum chloride solution or the mixed solution of palladium chloride and platinum chloride, the corresponding precious metal platinum and palladium can be produced by existing processes such as electrolysis; In the mixed solution of platinum, palladium and platinum can be obtained respectively by controlling the difference in potential during the electrolysis process. The gold chloride solution can be electrolyzed by hydrometallurgy technology to obtain gold with a purity of 99.99%. the

In addition, since the functionalized mesoporous molecular sieve prepared by the present invention has its adsorption capacity for noble metal ions under different conditions, those skilled in the art can, according to the content of noble metal ions in the ore slurry and the functionalized mesoporous molecular sieve The adsorption capacity determines the dosage ratio of the two. the

Compared with the prior art, the present invention adopts the functionalized mesoporous molecular sieve capable of selectively adsorbing precious metals to recover precious metals, the process is simple, and the purpose of separation, analysis and enrichment of precious metal ions can be achieved only by simply adjusting the acidity of the solution; the function The adsorption efficiency of the mesoporous molecular sieve is high, and its adsorption efficiency of gold ions is over 98%, and the efficiency of adsorption of palladium ions and platinum ions is also over 90%. The recovery process of the present invention does not involve highly toxic substances, and has the advantage of environmental protection. the

4. Description of drawings

Fig. 1 is the process flow diagram of utilizing SH-MCM-41 to reclaim precious metals from waste electronic circuit boards in the third embodiment of the present invention. the

5. Specific implementation

Technical scheme of the present invention will be further described below with specific embodiment, but protection scope of the present invention is not limited to this:

Embodiment one:

1. Grafting of functional groups

Put 2.5g of MCM-41 powder into 250ml of anhydrous toluene containing 0.1mol/L aminopropane (C ₃ H ₇ NH ₂ ), reflux at 120°C for 18 hours, and graft functional groups on molecular sieves- NH ₂ , then filter the MCM-41 powder, and dry the powder at 110° C. for 12 hours to evaporate the toluene completely to obtain the NH ₂ -MCM-41 selective adsorption noble metal functional molecular sieve. Using the same method to graft the functional group -SH, the SH-MCM-41 selective adsorption noble metal functional molecular sieve was obtained. The physical and chemical properties of the prepared NH ₂ -MCM-41 and SH-MCM-41 are shown in Table 1.

2. Selective adsorption and desorption of precious metals

Put 50g NH ₂ -MCM-41 selective adsorption noble metal functional molecular sieve into 2.5 liters of solutions containing 276g gold chloride (AuCl ₃ ) and 59g palladium chloride (PdCl ₃ ), adjust the pH value of the solution to 1.0, and After stirring at room temperature for 2 hours, filter out the molecular sieve loaded with noble metal ions, and measure the content of gold and palladium ions in the solution. Then the molecular sieve loaded with noble metal ions was washed with 5M HCl solution to obtain a solution containing only _PdCl3 and the resolved molecular sieve. Put the functional molecular sieve into the solution containing the last filtration again, adjust the pH value of the solution to 2.5, filter the molecular sieve loaded with gold ions after stirring at room temperature for 2 hours, and measure the content of gold and palladium ions in the solution . And wash the molecular sieve loaded with gold ions with 5M HCl solution to obtain AuCl ₃ solution and molecular sieve, the molecular sieve can be used again.

Similarly, SH-MCM-41 is used as a functional molecular sieve for selective adsorption of noble metals for selective adsorption and separation of noble metals. the

The adsorption properties of NH ₂ -MCM-41 and SH-MCM-41 are shown in Table 1.

Table 1: Physical, chemical and adsorption properties of mesoporous molecular sieves before and after grafting functional groups

Table 1 shows the physical, chemical and adsorption properties of noble metal ions of three different molecular sieves. From the results of N ₂ low temperature adsorption test, it can be seen that while -NH ₂ or -SH groups are grafted on the surface of the molecular sieve, they are also successfully grafted on the inner wall of the mesoporous molecular sieve, making the inner diameter of the mesoporous molecular sieve smaller, such as grafting on the - After adding NH ₂ groups, the inner diameter decreases from 3.09nm to 2.92nm, so that the specific surface area of molecular sieves before and after grafting functional groups decreases, and the BET specific surface decreases from 1140m ² /g to 774m ² /g, but there is no grafting of functional groups Molecular sieves with agglomerates do not have the effect of adsorbing noble metal ions, but molecular sieves grafted with functional groups have a strong selective and efficient ability to adsorb noble metals in acidic solutions. As can be seen from the adsorption test results, the NH ₂ -MCM-41 molecular sieve can almost adsorb all noble metal ions in the solution, and 100% of the gold ions and 99.2% of the palladium ions in the solution are adsorbed; and simply adjust the pH of the solution from 1.0 to 2.5, the separation of gold and palladium ions can be achieved better. Compared with NH ₂ -MCM-41 molecular sieve, the adsorption capacity of SH-MCM-41 molecular sieve is slightly worse. Using SH-MCM-41 molecular sieve, 99.3% of gold ions and 91.9% of palladium ions in the solution can be effectively adsorbed and separated.

Example 2: Using SBA-15 molecular sieve to graft functional groups and its application in separating gold and platinum

1. Grafting of functional groups

Put 2.5g of SBA-15 powder into 250ml of anhydrous toluene containing 0.1mol/L aminopropane (C ₃ H ₇ NH ₂ ), reflux at 120°C for 18 hours, and graft functional groups on molecular sieves- NH ₂ , then filter the SBA-15 powder, and dry the powder at 110° C. for 12 hours to evaporate the toluene completely to obtain the NH ₂ -SBA-15 selective adsorption noble metal functional molecular sieve.

2. Selective adsorption and separation of gold and platinum

Put 25g NH ₂ -SBA-15 selective adsorption precious metal functional molecular sieve into 2 liters of solutions containing 76g gold chloride (AuCl ₃ ) and 24g platinum chloride (PtCl ₃ ), adjust the pH value of the solution to 1.0, and After stirring at room temperature for 2 hours, the functional molecular sieve loaded with gold and platinum ions was filtered out, and the content of gold and platinum ions in the solution was measured. Then the molecular sieve loaded with noble metal ions was washed with 5M HCl solution to obtain a solution containing only _PtCl3 and the molecular sieve that was resolved. Put the functional molecular sieve into the solution containing the last filtration again, adjust the pH value of the solution to 2.5, also filter the molecular sieve loaded with gold ions after stirring at room temperature for 2 hours, and measure the content of gold and platinum ions in the solution , and the molecular sieve loaded with gold ions was washed with 5M HCl solution to obtain AuCl ₃ solution and molecular sieve. The adsorption results are shown in Table 2. The results show that NH ₂ -SBA-15 achieves the purpose of separating and enriching gold and platinum by adjusting the pH value of the solution. The molecular sieves washed with 5M HCl solution can be reused.

Table 2: Physical properties and adsorption separation of SBA-15 before and after grafting functional groups

Embodiment three:

Selective adsorption of precious metal functional molecular sieves for recovery of precious metals from waste electronic circuit boards. Discarded mobile phone electronic circuit boards are pulverized, superfinely pulverized and separated by high-voltage electrostatics, and the obtained metal powder is dissolved in concentrated hydrochloric acid:concentrated nitric acid with a volume ratio of 1:2 to obtain a solution containing metal ions. The solution contains 0.015mol of gold; 0.009mol of platinum; 0.47mol of copper; 0.21mol of tin; 0.077mol of lead; 0.27mol of iron; Use sodium hydroxide solution to adjust the pH value of the solution to about 1.0, put 5g SH-MCM-41 molecular sieve into the metal solution, and stir at room temperature for 12 hours to allow the molecular sieve to fully absorb noble metal ions. After filtering the solution, molecular sieves loaded with precious metal ions and a solution containing unadsorbed metals are obtained. the

Adopt 5M HCl to wash loaded noble metal molecular sieve, obtain 0.009 platinum chloride (being 100% platinum ion) and the gold chloride of 0.0002mol (1.3% gold ion). There are no platinum ions in the solution containing unadsorbed metals, indicating that the platinum ions have been adsorbed and separated by the functional molecular sieve, while most of the gold ions and other metals remain in the solution. the

Adjust the pH value of the solution obtained after filtration to about 2.5, put the molecular sieve washed with 5M HCl into the metal solution again, and stir at room temperature for 12 hours to allow the molecular sieve to fully absorb metal ions. After filtering, a molecular sieve loaded with 0.0148 mol of gold chloride (AuCl ₃ ) and trace amounts of other metals (Cu and Ni) and a solution containing unadsorbed metals are obtained, thereby realizing the separation of gold ions from other metal ions. Then, the gold-loaded functional molecular sieve is washed with 5M HCl to obtain a gold chloride solution, and the functional molecular sieve obtained after filtration can be reused for adsorbing precious metals. Figure 1 shows the process of recovering precious metals from waste electronic circuit boards using SH-MCM-41 and the experimental data of Example 3.

Claims (5)

1. functional mesoporous molecular sieve, make by the following method: with silicon is that mesopore molecular sieve places the dry toluene that contains 0.1～0.5mol/L aminopropane or propanethiol to reflux 12～24 hours in 100～120 ℃, filtration and dry under 150～180 ℃ of temperature obtains amido or mercapto-functionalized mesopore molecular sieve then.

2. functional mesoporous molecular sieve as claimed in claim 1 is characterized in that described silicon is that mesopore molecular sieve is SBA-15 or MCM-41 mesopore molecular sieve.

3. functional mesoporous molecular sieve as claimed in claim 1 or 2 is in the application of reclaiming from the waste electronic wiring board in the noble metal, described noble metal is one or both and the gold in platinum and the palladium, and the described noble metal that reclaims from the waste electronic wiring board comprises the steps:

(a) the waste electronic wiring board pulverized, separated and obtain non-metal powder and metal dust, metal dust is dissolved with strong acid, contain one or both and gold ion in platinum ion and the palladium ion in the gained dissolving metal liquid;

(b) regulate about the pH value to 1 of dissolving metal liquid, functional mesoporous molecular sieve is put into dissolving metal liquid, at room temperature stirred 8～12 hours, filter the molecular sieve and the filtrate A that obtain being loaded with platinum ion and/or palladium ion;

(c) clean the molecular sieve be loaded with platinum ion and/or palladium ion with 3～6M hydrochloric acid, filter the functional mesoporous molecular sieve that obtains platinum chloride and/or palladium chloride solution and reactivate;

(d) regulate about the pH value to 2.5 of filtrate A, functional mesoporous molecular sieve is put into filtrate A, at room temperature stirred 8～12 hours, filter and obtain carrying golden molecular sieve, clean a year golden molecular sieve with 3～6M hydrochloric acid, filter the functional mesoporous molecular sieve that obtains chlorogold solution and reactivate.

4. functional mesoporous molecular sieve as claimed in claim 3 is characterized in that in the application of reclaiming in the noble metal the described strong acid of step (a) is the nitration mixture or the chloroazotic acid of 2: 1 red fuming nitric acid (RFNA) of volume ratio and concentrated hydrochloric acid from the waste electronic wiring board.

5. functional mesoporous molecular sieve as claimed in claim 3 is characterized in that the molecular sieve or year golden molecular sieve that adopt the cleaning of 5M hydrochloric acid to be loaded with platinum ion and/or palladium ion in the application of reclaiming in the noble metal from the waste electronic wiring board.