Thiourea-based conjugated microporous polymer aerogel adsorbent as well as preparation method and application thereof

Abstract

The invention discloses a thiourea-based conjugated microporous polymer aerogel adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: in an inert gas atmosphere, adding an alkynyl aromatic hydrocarbon monomer, a thiourea halogenated hydrocarbon monomer, tetrakis (triphenylphosphine) palladium (0) and cuprous iodide into an organic solvent, heating to 80 DEG C in a stirring state, stopping stirring after colloid appears in a reaction solution, heating to 85 DEG C, and continuously reacting for 72 hours to obtain a reaction product; and sequentially washing and freeze-drying the reaction product to obtain the thiourea-based conjugated microporous polymer aerogel adsorbent. The adsorbent has a specific adsorption function on Au < 3 + >, and still has excellent removal efficiency on Au < 3 + > after multiple times of adsorption and desorption.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic porous aerogel materials, and in particular relates to a thiourea-based conjugated microporous polymer aerogel adsorbent and a preparation method and application thereof. Background Art

[0002] Gold (Au) plays a vital role in national defense science and technology, cutting-edge technologies, and clean energy. The current international gold market faces significant structural imbalances between supply and demand, driving the recycling of precious metal-rich electronic waste as a primary avenue for gold recovery. Adsorption, owing to its high separation efficiency and environmental friendliness, has become a core recovery technology. While mainstream adsorbents (such as porous carbon and chitosan) demonstrate potential, numerous challenges remain: (1) Poor material machinability Most of the gold adsorption materials reported so far (MOFs, COFs, biomass, etc.) are in the form of micro-nanoscale powders. They have insufficient processability and are difficult to recycle during use, which can easily cause secondary water pollution. (2) The adsorption material is not stable enough in acidic leachate Many gold adsorption materials reported so far (such as MOFs, polymers, and biomass) are prone to structural collapse, dissolution, or functional group degradation in the highly acidic and oxidizing environments of electronic waste leachates (usually containing aqua regia, cyanide, or strong oxidizing acids). This results in a short service life of the adsorption materials, and the adsorption capacity and selectivity rapidly decay in harsh environments, making them unable to meet the stability requirements of practical applications. (3) Cyclic stability needs to be improved Many adsorption materials with gold selectivity (such as materials containing thiourea, thioether, amino, etc.) often have their functional groups grafted onto the support surface or skeleton through post-synthetic modification. On the one hand, the modification process is complicated, which increases the synthesis steps and cost. On the other hand, in strong acidic or repeated adsorption-desorption processes, the grafted functional groups are easily hydrolyzed, broken or oxidized and fall off, resulting in a significant decrease in the adsorption capacity and selectivity of the material.

[0003] Conjugated microporous polymers (CMPs) are a class of organic porous materials. Their three-dimensional porous rigid network is composed of covalently linked π-conjugated structural units, resulting in a large specific surface area and permanent nanoscale pores. Their structure contains numerous rigid building blocks, such as benzene rings, acetylenic bonds, and double bonds, enabling them to maintain structural stability even under acidic conditions. However, due to the irreversible nature of the CMPs synthesis process, most synthesized CMPs are amorphous powders, limiting their practical application. Furthermore, there are currently no reports on the application of CMPs for the enrichment of precious metals from electronic waste. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a thiourea-based conjugated microporous polymer aerogel adsorbent.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned thiourea-based conjugated microporous polymer aerogel adsorbent.

[0006] Another object of the present invention is to provide an application of the above-mentioned thiourea-based conjugated microporous polymer aerogel adsorbent.

[0007] The present invention is achieved by a method for preparing a thiourea-based conjugated microporous polymer aerogel adsorbent, the method comprising the following steps: (1) Under an inert gas atmosphere, an alkynyl aromatic hydrocarbon monomer, a thiourea halide hydrocarbon monomer, tetrakis(triphenylphosphine)palladium(0), and cuprous iodide are added to an organic solvent, and the temperature is raised to 80°C while stirring. When a colloid appears in the reaction solution, stirring is stopped, and the temperature is raised to 85°C and the reaction is continued for 72 hours to obtain a reaction product; (2) The reaction product is washed and freeze-dried in sequence to obtain a thiourea-based conjugated microporous polymer aerogel adsorbent.

[0008] Preferably, in step (1), the alkynyl aromatic hydrocarbon monomer is 1,3,5-triethynylbenzene or tris(4-ethynylphenyl)amine, and the thiourea-based halogenated hydrocarbon monomer is 1-(2,4,6-trichlorophenyl)thiourea.

[0009] Preferably, in step (1), the molar ratio of the alkynyl group of the alkynyl aromatic hydrocarbon monomer to the halogen of the thiourea halocarbon monomer is 2:1.

[0010] Preferably, in step (1), the molar volume ratio of the alkynyl aromatic hydrocarbon monomer, the thiourea halogenated hydrocarbon monomer, tetrakis(triphenylphosphine)palladium, cuprous iodide, and the organic solvent is 1.11-2.34 mmol: 0.56-1.17 mmol: 152.31 mg: 50.77 mg: 14.8 mL.

[0011] Preferably, in step (1), the organic solvent is a mixture of N,N-dimethylformamide and triethylamine in a volume ratio of 1:1.

[0012] Preferably, in step (1), the inert gas in the inert atmosphere is nitrogen.

[0013] Preferably, in step (2), the washing is performed by washing with chloroform, acetone, and methanol twice in sequence and then washing with water; and the freeze-drying is performed by drying at -50°C for 12 hours.

[0014] The present invention further discloses a thiourea-based conjugated microporous polymer aerogel adsorbent prepared by the method.

[0015] The present invention further discloses the application of the above thiourea-based conjugated microporous polymer aerogel adsorbent in recycling precious metal Au from electronic waste. 3+ Application in.

[0016] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects: the present invention utilizes the permanent porosity, good chemical stability and thermal stability, controllable structural flexibility and diversity of building modules of CMPs, performs molecular design of specific functional groups on the building block units, and introduces monomers with thiourea groups into CMPs aerogels by Sonogashira-Hagihara cross-coupling reaction, so that the adsorbent of the present invention has the ability to absorb Au. 3+ In addition, the rigid unit structure of CMPs can effectively avoid structural collapse in harsh environments (such as acidic environments). In the study of recyclability, it was found that the adsorbent of the present invention has a specific adsorption function for Au after multiple adsorption and desorption experiments. 3+ Still has excellent removal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a scanning electron microscope image of CMP-1 provided in an embodiment of the present invention; Figure 2 is a scanning electron microscope image of CMP-2 provided in an embodiment of the present invention; Figure 3 is the adsorption amount-time fitting curve of CMP-1 provided in an embodiment of the present invention; Figure 4 is the adsorption amount-time fitting curve of CMP-2 provided in an embodiment of the present invention; Figure 5 is the isothermal adsorption fitting curve of CMP-1 provided in an embodiment of the present invention; Figure 6 is the isothermal adsorption fitting curve of CMP-2 provided in an embodiment of the present invention; Figure 7 is the removal efficiency in the cyclic adsorption experiments of CMP-1 and CMP-2 provided in the embodiments of the present invention; Figure 8 It is the removal efficiency of different metal ions by CMP-1 and CMP-2 provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Example 1 (1) 1,3,5-Triethynylbenzene (2.34 mmol, 351.42 mg), 1-(2,4,6-trichlorophenyl)thiourea (1.17 mmol, 298.99 mg), tetrakis(triphenylphosphine)palladium(0) (152.31 mg) and cuprous iodide (50.77 mg) were added to a glass reactor (3.6 cm in diameter, 12 cm in height); after sealing and degassing with N2 for 20 min, 7.4 mL of N,N-dimethylformamide and 7.4 mL of triethylamine were added in sequence, and then degassed under magnetic stirring for another 20 min, the temperature was slowly increased to 80°C and stirring was continued until colloid appeared and stirring was stopped. The temperature was raised to 85°C and the reaction was continued for 72 h to obtain the reaction product; (2) The obtained reaction product was washed twice with chloroform, acetone, and methanol in sequence, and then washed with water, and dried at -50°C for 12 hours to obtain a thiourea-based conjugated microporous polymer aerogel adsorbent CMP-1.

[0020] Example 2 (1) Tris(4-ethynylphenyl)amine (1.11 mmol, 351.42 mg), 1-(2,4,6-trichlorophenyl)thiourea (0.56 mmol, 141.84 mg), tetrakis(triphenylphosphine)palladium(0) (152.31 mg) and cuprous iodide (50.77 mg) were added to a glass reactor (3.6 cm in diameter, 12 cm in height); after sealing and degassing with N2 for 20 min, 7.4 mL of N,N-dimethylformamide and 7.4 mL of triethylamine were added in sequence, and then degassed under magnetic stirring for another 20 min, the temperature was slowly increased to 80°C and stirring was continued until colloid appeared, and stirring was stopped. The temperature was raised to 85°C and the reaction was continued for 72 h to obtain the reaction product; (2) The obtained reaction product was washed twice with chloroform, acetone, and methanol in sequence, and then washed with water, and dried at -50°C for 12 hours to obtain a thiourea-based conjugated microporous polymer aerogel adsorbent CMP-2.

[0021] Effect embodiment

[0022] 1. Microstructure The thiourea-based conjugated microporous polymer aerogel adsorbents CMP-1 and CMP-2 were observed by scanning electron microscopy. Figure 1 、 Figure 2 As shown in the figure, it can be clearly seen that CMP-1 and CMP-2 are network structures constructed by nanoparticles.

[0023] 2. Study on aerogel adsorption performance Au in chloroauric acid solution 3+ The following experimental determination was performed with α as the target ion.

[0024] (1) Test adsorption capacity-time curve Under acidic conditions, 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of the present invention was added to 10 mL of AuCl4 - The solution was sampled after 10 min, 20 min, 30 min, 40 min, 180 min, 360 min, 540 min, and 720 min, respectively. After separation through a 0.45 μm filter membrane, the residual gold concentration was determined by ICP-OES. The pseudo-first-order / pseudo-second-order kinetic model was fitted, and the adsorption amount-time fitting curve of CMP-1 (Q e -t curve) such as Figure 3 As shown, the adsorption amount-time fitting curve of CMP-2 is as follows Figure 4 shown.

[0025] Depend on Figure 3 、 Figure 4 It can be seen that both CMP-1 and CMP-2 reached adsorption equilibrium in 12 h, which is consistent with the pseudo-second-order kinetic model. The adsorption process is dominated by the chemical rate-controlling step, including: the thiourea group and AuCl4 - coordination bond formation (soft acid-soft base interaction), ion diffusion and chelation within the aerogel pores.

[0026] (2) Test adsorption isotherm 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of the present invention was added to 10 mL of AuCl4 - The solution (concentration gradient: 300~2000 ppm) was stirred at 150 rpm for 12 h until equilibrium. After filtration, the equilibrium concentration was determined by ICP-OES. The Langmuir and Freundlich models were used to fit the adsorption behavior. The results are shown in Figure 2. Figure 5 and Figure 6 shown.

[0027] Figure 5 、 Figure 6 The isothermal adsorption curves of CMP-1 and CMP-2 are consistent with the Langmuir adsorption model. It can be seen from the figure that the maximum adsorption capacities of CMP-1 and CMP-2 are 1589 mg / g and 2247 mg / g, respectively.

[0028] (3) Recycling performance test Take 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of the present invention to treat 10 mL of 300 ppm AuCl4 - Solution, solid-liquid separation after adsorption. 3+The adsorbent was desorbed with 40 mL of eluent (1 M thiourea / 1 M HCl, volume ratio 1:1) for 30 min and washed with deionized water until neutral. The eluted adsorbent was recycled five times (four adsorption-desorption cycles) and the removal efficiency was quantitatively evaluated by ICP-OES. The results are shown in Figure 2. Figure 7 shown.

[0029] Figure 7 The removal efficiencies of CMP-1 and CMP-2 in the adsorption-desorption cycle experiment were 88.2% and 96.3% respectively after five cycles, demonstrating the excellent cyclic stability of the thiourea-based conjugated microporous polymer aerogel adsorbent.

[0030] (4) Selective testing A discarded computer CPU chip was placed in a mixed solution consisting of 1µL of pyridine, 750mg of NBS, and 120mL of deionized water and allowed to stand for 4 days. The solution was filtered and acidified with 1M HCl to adjust the pH to 2. 10mL of the solution was then added to 10mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of the present invention. After 12 hours of adsorption, the adsorbent's removal efficiency for different metal ions was quantitatively evaluated using ICP-OES. The results are shown in Figure 2. Figure 8 shown.

[0031] CMP-1 and CMP-2 were used to selectively test gold in actual electronic waste. The results are as follows: Figure 8 As shown, the results show that in the presence of a large amount of Cu 2+ In the case of other metal ions, CMP-1 and CMP-2 have a significant effect on Au 3+ showed a removal efficiency close to 100%, while for Cu 2+ Other competing ions have almost no adsorption.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a thiourea-based conjugated microporous polymer aerogel adsorbent, characterized in that: The preparation method comprises the following steps: (1) Under an inert gas atmosphere, an alkynyl aromatic hydrocarbon monomer, a thiourea halide hydrocarbon monomer, tetrakis(triphenylphosphine)palladium(0), and cuprous iodide are added to an organic solvent, and the temperature is raised to 80°C while stirring. When a colloid appears in the reaction solution, stirring is stopped, and the temperature is raised to 85°C and the reaction is continued for 72 hours to obtain a reaction product; (2) The reaction product is washed and freeze-dried in sequence to obtain a thiourea-based conjugated microporous polymer aerogel adsorbent.

2. The preparation method according to claim 1, wherein In step (1), the alkynyl aromatic hydrocarbon monomer is 1,3,5-triethynylbenzene or tris(4-ethynylphenyl)amine, and the thiourea-based halogenated hydrocarbon monomer is 1-(2,4,6-trichlorophenyl)thiourea.

3. The preparation method according to claim 1, wherein In step (1), the molar ratio of the alkynyl group of the alkynyl aromatic hydrocarbon monomer to the halogen of the thiourea halocarbon monomer is 2:

1.

4. The preparation method according to claim 3, wherein In step (1), the molar volume ratio of the alkynyl aromatic hydrocarbon monomer, the thiourea halide hydrocarbon monomer, tetrakis(triphenylphosphine)palladium(0), cuprous iodide, and the organic solvent is 1.11-2.34 mmol: 0.56-1.17 mmol: 152.31 mg: 50.77 mg: 14.8 mL.

5. The preparation method according to claim 4, wherein In step (1), the organic solvent is a mixture of N,N-dimethylformamide and triethylamine in a volume ratio of 1:

1.

6. The preparation method according to claim 1, wherein In step (1), the inert gas in the inert atmosphere is nitrogen.

7. The preparation method according to claim 1, wherein In step (2), the washing is performed by washing with chloroform, acetone, and methanol twice in sequence and then washing with water; the freeze-drying is performed by drying at -50°C for 12 hours.

8. The thiourea-based conjugated microporous polymer aerogel adsorbent prepared by the preparation method according to any one of claims 1 to 7.

9. The thiourea-based conjugated microporous polymer aerogel adsorbent according to claim 8 is used to recover the precious metal Au from electronic waste 3 + Application in.

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