Thiourea-based conjugated microporous polymer aerogel adsorbents, methods of making and applications thereof

Abstract

The application discloses a thioureido conjugated microporous polymer aerogel adsorbent and a preparation method and application thereof. The application adds an alkynyl aromatic hydrocarbon monomer, a thioureido halogenated hydrocarbon monomer, tetrakis(triphenylphosphine)palladium(0) and cuprous iodide into an organic solvent under an inert gas atmosphere, and the mixture is heated to 80 DEG C under stirring, the stirring is stopped after the appearance of a colloid in the reaction solution, the mixture is continuously reacted for 72 hours after being heated to 85 DEG C, and a reaction product is obtained. The reaction product is sequentially subjected to washing and freeze-drying, and a thioureido conjugated microporous polymer aerogel adsorbent is obtained. The adsorbent has specific adsorption function for Au 3+ , and still has excellent removal efficiency for Au 3+ after multiple adsorption and desorption.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic porous aerogel materials, and particularly relates to a thioureido-based conjugated microporous polymer aerogel adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Gold (Au) plays an important role in the fields of national defense technology, cutting-edge technology and clean energy. The current international gold market is facing a significant structural contradiction between supply and demand, prompting the recycling of electronic waste resources rich in precious metals to become the main way of gold recovery. Adsorption method is established as the core recovery technology due to its high separation efficiency and environmental friendliness. Although the mainstream adsorbents (such as porous carbon, chitosan, etc.) show potential, there are still many problems:

[0003] (1) Poor material processability

[0004] Most of the gold adsorption materials (MOFs, COFs, biomass, etc.) reported at present are in the form of micro-nano powder, which has poor processability and is difficult to recover in use, and may cause secondary pollution of water bodies;

[0005] (2) Insufficient stability of adsorption materials in acidic leaching solution

[0006] Many gold adsorption materials (such as MOFs, polymers, biomass, etc.) reported at present are easy to collapse, dissolve or functional group degradation in strong acid and strong oxidizing environment of electronic waste leaching solution (usually containing aqua regia, cyanide or strong oxidizing acid), which leads to short service life of adsorption materials, rapid decay of adsorption capacity and selectivity in harsh environment, and cannot meet the requirements of stability in actual application;

[0007] (3) Cycle stability needs to be improved

[0008] Many adsorption materials with gold selectivity (such as materials containing thiourea, sulfide, amino, etc.), the functional groups are often grafted to the surface or skeleton of the carrier by post-synthesis modification, on the one hand, the modification process is complex, which increases the synthesis steps and cost, on the other hand, in strong acid or repeated adsorption-desorption process, the grafted functional groups are easy to hydrolyze, break or oxidize and fall off, which leads to significant decrease of adsorption capacity and selectivity of the material.

[0009] Conjugated microporous polymers (CMPs) are a class of organic porous materials, whose three-dimensional rigid networks are formed by π-conjugated building blocks linked by covalent bonds. CMPs have large specific surface area and permanent nanoporous structure, and contain a large number of rigid structural units such as benzene ring, alkyne bond and double bond, which can keep the structure stable under acidic conditions. However, due to the irreversibility of the synthesis process, most of the synthesized CMPs are amorphous powders, which limits their application in practical environment. In addition, there is no report on the application of CMPs in the enrichment of precious metals in electronic waste. SUMMARY

[0010] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a thioureido-based conjugated microporous polymer aerogel adsorbent.

[0011] Another purpose of the present application is to provide a preparation method of the above-mentioned thioureido-based conjugated microporous polymer aerogel adsorbent.

[0012] Still another purpose of the present application is to provide the application of the above-mentioned thioureido-based conjugated microporous polymer aerogel adsorbent.

[0013] The present application is realized in this way, a preparation method of a thioureido-based conjugated microporous polymer aerogel adsorbent, the method comprising the following steps:

[0014] (1) under the atmosphere of inert gas, alkynyl aromatic hydrocarbon monomer, thioureido halogenated hydrocarbon monomer, tetrakis (triphenylphosphine) palladium (0), cuprous iodide are added to organic solvent, under the condition of stirring, the temperature is raised to 80℃, after the appearance of colloidal in the reaction solution, the stirring is stopped, the temperature is raised to 85℃, and then the reaction is continued for 72h, to obtain the reaction product;

[0015] (2) the reaction product is sequentially washed and freeze-dried to obtain the thioureido-based conjugated microporous polymer aerogel adsorbent.

[0016] Preferably, in step (1), the alkynyl aromatic hydrocarbon monomer is 1,3,5-triethynylbenzene or tri (4-ethynylphenyl) amine, and the thioureido halogenated hydrocarbon monomer is 1- (2,4,6-trichlorophenyl) thiourea.

[0017] Preferably, in step (1), the molar ratio of the alkynyl group of the alkynyl aromatic hydrocarbon monomer to the halogen of the thioureido halogenated hydrocarbon monomer is 2:1.

[0018] Preferably, in step (1), the molar volume ratio of the alkynyl aromatic hydrocarbon monomer, the thioureido halogenated hydrocarbon monomer, tetrakis (triphenylphosphine) palladium, cuprous iodide, and the organic solvent is 1.11 ~ 2.34mmol: 0.56 ~ 1.17mmol: 152.31mg: 50.77mg: 14.8mL.

[0019] Preferably, in step (1), the organic solvent is a mixture of N,N-dimethylformamide and triethylamine in a volume ratio of 1:1.

[0020] Preferably, in step (1), the inert gas in the inert atmosphere is nitrogen.

[0021] Preferably, in step (2), the washing is performed by washing twice with chloroform, acetone and methanol in sequence, followed by washing with water; the freeze drying is performed by drying at -50°C for 12 hours.

[0022] This invention further discloses the thiourea-based conjugated microporous polymer aerogel adsorbent prepared by the above method.

[0023] This invention further discloses the application of the above-mentioned thiourea-based conjugated microporous polymer aerogel adsorbent in the recycling of the precious metal Au from electronic waste. 3+ Applications in [the field].

[0024] Compared to the shortcomings and deficiencies of existing technologies, this invention has the following beneficial effects: This invention utilizes the permanent porosity, good chemical and thermal stability, controllable structural flexibility, and diverse building blocks of CMPs to perform molecular design of specific functional groups on the building block units. A Sonogashira-Hagihara cross-coupling reaction is used to introduce monomers with thiourea groups onto the CMPs aerogel, enabling the adsorbent of this invention to possess Au... 3+ It exhibits specific adsorption capabilities. Furthermore, the rigid unit structure of CMPs effectively prevents structural collapse in harsh environments (such as acidic environments). In recyclability studies, it was found that the adsorbent of this invention, after multiple adsorption-desorption experiments, effectively retains Au. 3+ It still has excellent removal efficiency. Attached Figure Description

[0025] Figure 1 These are scanning electron microscope images of CMP-1 provided in the embodiments of the present invention;

[0026] Figure 2 These are scanning electron microscope images of CMP-2 provided in the embodiments of the present invention;

[0027] Figure 3 This is the adsorption amount-time fitting curve of CMP-1 provided in the embodiments of the present invention;

[0028] Figure 4 This is the adsorption amount-time fitting curve of CMP-2 provided in the embodiments of the present invention;

[0029] Figure 5 This is the isothermal adsorption fitting curve of CMP-1 provided in the embodiments of the present invention;

[0030] Figure 6 This is the isothermal adsorption fitting curve of CMP-2 provided in the embodiments of the present invention;

[0031] Figure 7 This refers to the removal efficiency of CMP-1 and CMP-2 in the cyclic adsorption experiment provided in the embodiments of the present invention;

[0032] Figure 8 This refers to the removal efficiency of CMP-1 and CMP-2 for different metal ions provided in the embodiments of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0034] Example 1

[0035] (1) 1,3,5-triethynylbenzene (2.34 mmol, 351.42 mg), 1-(2,4,6-trichlorophenyl)thiourea (1.17 mmol, 298.99 mg), tetra(triphenylphosphine)palladium (0) (152.31 mg) and cuprous iodide (50.77 mg) were added to a glass reactor (3.6 cm in diameter and 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 for another 20 min under magnetic stirring. The temperature was slowly increased to 80 °C and stirring was continued until a colloid appeared. The stirring was then stopped, and the temperature was raised to 85 °C and the reaction was continued for 72 h to obtain the reaction product.

[0036] (2) The obtained reaction product was washed twice with chloroform, acetone and methanol, and then washed with water. It was dried at -50℃ for 12h to obtain thiourea-based conjugated microporous polymer aerogel adsorbent CMP-1.

[0037] Example 2

[0038] (1) Tris(4-ethynylphenyl)amine (1.11 mmol, 351.42 mg), 1-(2,4,6-trichlorophenyl)thiourea (0.56 mmol, 141.84 mg), tetra(triphenylphosphine)palladium (0) (152.31 mg) and cuprous iodide (50.77 mg) were added to a glass reactor (3.6 cm in diameter and 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 for another 20 min under magnetic stirring. The temperature was slowly increased to 80 °C and stirring was continued until a colloid appeared. The stirring was then stopped, and the temperature was raised to 85 °C and the reaction was continued for 72 h to obtain the reaction product.

[0039] (2) The obtained reaction product was washed twice with chloroform, acetone and methanol, and then washed with water. It was dried at -50℃ for 12h to obtain thiourea-based conjugated microporous polymer aerogel adsorbent CMP-2.

[0040] Effect Example

[0041] 1. Microstructure

[0042] The thiourea-based conjugated microporous polymer aerogel adsorbents CMP-1 and CMP-2 were observed using scanning electron microscopy, and the results are as follows: Figure 1 , Figure 2 As shown in the figure, CMP-1 and CMP-2 are network structures constructed from nanoparticles.

[0043] 2. Study on the adsorption properties of aerogels

[0044] Au in chloroauric acid solution 3+ The following experiments were conducted to determine the target ion.

[0045] (1) Test adsorption capacity-time curve

[0046] Under acidic conditions, 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of this invention was added to 10 mL of AuCl4. - The solution was sampled at 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. A pseudo-first-order / pseudo-second-order kinetic model was fitted, and the adsorption capacity-time fitting curve of CMP-1 (Q) was obtained. e -t curve) such as Figure 3 As shown, the adsorption amount-time fitting curve of CMP-2 is as follows: Figure 4 As shown.

[0047] Depend onFigure 3 , Figure 4 It can be seen that both CMP-1 and CMP-2 reach adsorption equilibrium at 12 h, which conforms to the pseudo-second-order kinetic model. The adsorption process is dominated by the chemical rate-determining step, which includes the reaction of the thiourea group and AuCl4. - Coordination bond formation (soft acid-soft base interaction), ion diffusion and chelation within the aerogel channels.

[0048] (2) Test the adsorption isotherm

[0049] Add 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of this invention to 10 mL of AuCl4. - The solution (concentration gradient: 300–2000 ppm) was stirred at 150 rpm for 12 h until equilibrium was reached. After filtration, the equilibrium concentration was determined by ICP-OES. The adsorption behavior was fitted using Langmuir and Freundlich models, respectively, and the results are shown below. Figure 5 and Figure 6 As shown.

[0050] Figure 5 , Figure 6 The isothermal adsorption curves for CMP-1 and CMP-2 are shown in the figure, which conform to the Langmuir adsorption model. The maximum adsorption capacities of CMP-1 and CMP-2 are 1589 mg / g and 2247 mg / g, respectively.

[0051] (3) Cyclic regeneration performance test

[0052] Take 5 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of this invention and treat 10 mL of 300 ppm AuCl4. - Solution, followed by solid-liquid separation after adsorption. For adsorbed Au... 3+ The adsorbent was eluented with 40 mL of elution buffer (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 5 times (4 adsorption-desorption cycles), and the removal efficiency was quantitatively evaluated by ICP-OES. The results are as follows: Figure 7 As shown.

[0053] Figure 7 The removal efficiencies of CMP-1 and CMP-2 in the adsorption-desorption cycle experiment are shown. The results show that after 5 cycles, CMP-1 and CMP-2 still maintained adsorption efficiencies of 88.2% and 96.3%, respectively, indicating that the thiourea-based conjugated microporous polymer aerogel adsorbent of the present invention has excellent cycle stability.

[0054] (4) Selective testing

[0055] A discarded computer CPU chip was placed in a mixed solution consisting of 1 µL pyridine, 750 mg NBS, and 120 mL deionized water and allowed to stand for 4 days. The solution was filtered, and the pH was adjusted to 2 with 1 M HCl. 10 mg of the thiourea-based conjugated microporous polymer aerogel adsorbent of this invention was added to 10 mL of the solution. After adsorption for 12 h, the removal efficiency of the adsorbent for different metal ions was quantitatively evaluated using ICP-OES. The results are as follows: Figure 8 As shown.

[0056] Selective testing of gold in actual electronic waste was performed using CMP-1 and CMP-2, and the results are as follows: Figure 8 As shown, the results indicate that in the presence of a large amount of Cu 2+ In the case of other metal ions, CMP-1 and CMP-2 are effective against Au. 3+ It exhibits a removal efficiency close to 100%, while for Cu 2+ Other competing ions have almost no adsorption capacity.

[0057] 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 within the protection scope of the present invention.

Claims

1. A method for preparing a thiourea-based conjugated microporous polymer aerogel adsorbent, characterized in that, The method includes the following steps: (1) Under an inert gas atmosphere, alkynyl aromatic monomer, thiourea haloalkanes monomer, tetra(triphenylphosphine)palladium(0) and cuprous iodide were added to an organic solvent. The mixture was heated to 80°C with stirring. After the appearance of colloids in the reaction solution, stirring was stopped. The mixture was heated to 85°C and the reaction was continued for 72 h to obtain the reaction product. (2) The reaction products are washed and freeze-dried in sequence to obtain thiourea-based conjugated microporous polymer aerogel adsorbent.

2. The method as described in claim 1, characterized in that, In step (1), the alkynyl aromatic monomer is 1,3,5-triethynylbenzene or tris(4-ethynylphenyl)amine, and the thiourea-based halocarbon monomer is 1-(2,4,6-trichlorophenyl)thiourea.

3. The method as described in claim 1, characterized in that, In step (1), the molar ratio of the alkynyl group of the alkynyl aromatic monomer to the halogen of the thiourea halocarbon monomer is 2:

1.

4. The method as described in claim 3, characterized in that, In step (1), the molar volume ratio of the alkynyl aromatic monomer, thiourea haloalkanes monomer, tetra(triphenylphosphine)palladium(0), cuprous iodide, and organic solvent is 1.11~2.34 mmol: 0.56~1.17 mmol: 152.31 mg: 50.77 mg: 14.8 mL.

5. The method as described in claim 4, characterized in that, In step (1), the organic solvent is a mixture of N,N-dimethylformamide and triethylamine in a volume ratio of 1:

1.

6. The method as described in claim 1, characterized in that, In step (1), the inert gas in the inert gas atmosphere is nitrogen.

7. The method as described in claim 1, characterized in that, In step (2), the washing is performed by washing twice with chloroform, acetone and methanol in sequence, followed by 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 method according to any one of claims 1 to 7.

9. The thiourea-based conjugated microporous polymer aerogel adsorbent of claim 8 in the recycling of precious metal Au from electronic waste. 3 + Applications in [the field].

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