GB2609582A

GB2609582A - Preparation method of circular nanosheet with high-density sites, and use of circular nanosheet in adsorption of blood lead

Info

Publication number: GB2609582A
Application number: GB2215562.6A
Authority: GB
Inventors: Chen Xueping; Pan Jianming
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-09-24
Filing date: 2022-02-10
Publication date: 2023-02-08
Anticipated expiration: 2042-02-10
Also published as: GB202215562D0; GB2609582B; GB2609582A8

Abstract

The preparation of a circular nanosheet with high-density sites and its use in the removal of lead (Pb) ions in aqueous solution or blood is defined. The preparation method comprises synthesising the base Si-Cl capsule material, functionalising the surface and collapsing the capsule to form a hydroxyl-grafted nano-sheet (BM-OH), and the synthesis and attachment of a polymerizable cysteine monomer (D-SH) to obtain the circular nanosheet (BM-SH). The Si-Cl capsule is formed by the hydrolytic condensation of tetraethyl orthosilicate (TEOS) and 3-chloropropyltrimethoxysilane (3-CPTMS) at an oil and aqueous phase interface with n-pentanol and a mixture of ethanol and aqueous ammonia comprising sodium chloride (NaCl) as the oil and aqueous phases respectively. Functionalisation is achieved by reacting a dispersion of the Si-Cl material in ethanol, CuCl2.2H2O and N,N,N’,N’,N”-pentamethyldiethylenetriamine (PMDETA) in ethanol, ascorbic acid in water, and hydroxyethyl methacrylate (HEMA), followed by centrifugation and washing to form BM-OH. The polymerizable cysteine monomer (D-SH) is synthesised by reacting L-cysteine, methacrylic anhydride (MAA), and a sodium hydroxide (NaOH) solution. An ethanolic D-SH solution is then reacted with an aqueous dispersion of BM-OH and ceric ammonium nitrate (CAN) with concentrated sulfuric acid (H2SO4), and the product is centrifuged and washed to obtain the BM-SH.

Description

PREPARATION METHOD OF CIRCULAR NANOSHEET WITH HIGH-DENSITY

SITES, AND USE OF CIRCULAR NANOSHEET IN ADSORPTION OF BLOOD LEAD

TECHNICAL FIELD

The present disclosure belongs to the technical field of preparation of environmentally-friendly biomedical functional materials, and relates to a preparation method of a nanosheet for the selective and efficient enrichment of lead ions in blood. In particular, the present disclosure relates to a method for synthesizing a circular nanosheet adsorbent with high-density sites based on a salt-containing droplet system and a hyperbranching technique, and a use of the circular nanosheet adsorbent in the removal of lead ions in blood.

BACKGROUND

Lead is one of the most important heavy metal elements with wide distribution, corrosion resistance, and low melting point, and has prominent ductility and plasticity. Therefore, lead is widely used in chemical industry, military industry and construction industry. At present, the demand for lead resources in various countries worldwide continues to increase. In addition, due to the mining, smelting, and incomplete recovery of lead, the lead ion pollution is getting worse. Lead ions emitted enter organisms through water, air, soil, and the like, and finally enter the human body through a food chain. Studies have shown that lead is difficult to degrade in the human body, the continuous accumulation of lead in the human body can lead to blood lead, and excessive blood lead can directly cause lead poisoning, which is manifested as a disease of a human nervous system, a blood system, a digestive system, or the like. Children and pregnant women are especially vulnerable to lead pollution, and lead poisoning may cause mental retardation and reduced learning and perception abilities in children. In the last decade, blood lead poisoning incidents have happened from time to time in China, and the effective treatment of lead pollution and blood lead poisoning has attracted extensive attention.

Existing lead pollution control methods include a precipitation method, a flocculation method, an ion exchange method, and an adsorption method. The adsorption method can realize the efficient enrichment and recovery of lead ions without causing secondary pollution during adsorption, and has advantages such as simple operations and adsorbent recyclability. The adsorption method is recognized as an effective lead pollution control means. Therefore, the development of a new adsorbent to realize the selective recycling of lead ions and alleviate the hazard caused by lead ion pollution has become an extremely important research field. The current methods for treating lead poisoning still rely on the use of chelating agents to promote the excretion of lead, but side effects caused by the chelating agents are inevitable. In recent years, researchers hope for treating blood lead poisoning through a hemoperfusion strategy, in which the heavy metal lead is removed from blood through extracorporeal blood circulation to achieve the purpose of detoxification. The hemoperfusion strategy puts forward new requirements on the biocompatibility of adsorbents and the adsorption performance for lead ions. Therefore, it is of great significance to design and prepare an adsorbent and promote the application of the adsorbent in fields related to lead ion pollution control and blood lead poisoning treatment.

Silicon is the second most abundant chemical element in the earth crust after oxygen, and mainly exists in the forms of silica and silicates. Silica materials have excellent biocompatibility and are often used in the preparation of biological materials. In addition, a surface of a silica material has abundant functional groups and can be easily subjected to functional modification, and thus a silica material is an excellent adsorbent base material. Moreover, it has been reported that mercaptosuccinic acid (1\4 SA) with mercapto and carboxyl has a strong selective recognition ability for lead ions, and L-cysteine has a similar structure and the same functional groups, where electron-rich sulfur, nitrogen, and carboxyl oxygen highlight the potential application of the above compounds in the field of lead ion adsorption.

A morphological structure and the number of surface functional groups of an adsorbent determine the adsorption efficiency of a material. A porous adsorbent can both increase a specific surface area (SSA) and prolong an adsorption equilibrium time; and a nanosheet material has a large SSA, and can maximize the exposure of functional sites and shorten an equilibrium time. However, there are limited types of nanosheet adsorbents, and the site masking problem caused by nanosheet stacking has not been well solved. In addition, a density of functional sites on a surface of a traditional adsorbent is limited, resulting in an unsatisfactory adsorption capacity. The preparation methods of existing adsorbents are time-consuming and have reached the boundary in terms of material structure and surface functionalization. They are difficult to make a breakthrough progress on the basis of the inherent adsorption capacity. The hyperbranching technique can exponentially increase a number of grafted functional sites, thereby significantly increasing a density of functional sites on a surface of an adsorbent.

S UMMARY

In view of the problems in the prior art, the present disclosure first designs an emulsion system to prepare a nano-thick silica capsule through the anisotropy of an emulsion interface and the hydrolytic condensation of a silane coupling agent (SCA) and then prepare a circular silica nanosheet with surface wrinkles through the collapse of the spherical capsule, where the special structure of the circular silica nanosheet can effectively avoid the stacking of nanosheets, and then, the present disclosure adopts the silica nanosheet as a base material and cysteine as a functional monomer to design and synthesize a nanosheet adsorbent with high-density sites in combination with a hyperbranching technique, and the present disclosure uses the nanosheet adsorbent with the high-density sites in the removal of lead ions in an aqueous solution and blood. The nanosheet adsorbent exhibits a high adsorption rate and a high adsorption capacity, and exhibits excellent blood compatibility and high lead ion removal efficiency in blood lead adsorption and separation.

In order to solve the problem that the existing lead ion adsorbents have a low adsorption capacity and a low adsorption rate, the present disclosure constructs a nanosheet with a salt-containing droplet system, and increases an amount of grafted functional monomers through the hyperbranching technique to improve a site density on the surface of the adsorbent. In the present disclosure, a silica nanosheet is used as a base material and a functional monomer is designed and synthesized with cysteine as a unit to prepare a nanosheet adsorbent with high-density sites that exhibits excellent biocompatibility, and the nanosheet adsorbent is used in the removal of lead ions in an aqueous solution and blood.

In the present disclosure, since ethanol can reduce an interfacial tension between oil phase and aqueous phase, and a sodium chloride solution can enhance an interfacial tension between oil phase and aqueous phase, n-pentanol (as an oil phase) and a mixture of ethanol and sodium chloride-containing aqueous ammonia (as an aqueous phase) are mixed by hand-shaking and subjected to emulsification to obtain an emulsion droplet system, then tetraethyl orthosilicate (TEOS) and 3-chloropropyltrimethoxysilane (3-CPTMS) are added, the hydrolytic condensation of an SCA is catalyzed with aqueous ammonia to form a nanoshell layer at an interface between the droplet and the oil phase, a circular silica nanosheet (Si-C1) is obtained through centrifugation, washing with ethanol, and drying, then alcoholic hydroxyl is grafted in a large quantity on the surface of the circular silica nanosheet through ion-initiated free radical polymerization, and a cysteine functional monomer is polymerized on the surface of the material through ceric salt-initiated free radical polymerization to obtain a nanosheet adsorbent (BM-SH). In addition, in the present disclosure, a functional monomer is directly introduced to a site on the surface of Si-C1 to prepare an adsorbent (Si-SH) for comparative study.

The present disclosure adopts the following technical solutions A preparation method of a circular nanosheet with high-density sites is provided, including the following steps.

(1) synthesis of a base material Si-C1 dissolving sodium chloride (NaC1) in a predetermined amount of aqueous ammonia, adding an appropriate amount of ethanol, followed by hand-shaking for thorough mixing to obtain a resulting mixture; pouring the resulting mixture into a round-bottomed flask filled with n-pentanol, hand-shaking the round-bottomed flask for 30 s to 60 s, adding TEOS and 3-CPTMS successively to the round-bottomed flask, hand-shaking the round-bottomed flask for thorough mixing, and placing the round-bottomed flask in a water bath at 25°C to 30°C to allow a reaction to occur at 20 rpm to 200 rpm for 20 min to 180 mm; where in the step (1), the sodium chloride, the aqueous ammonia, the ethanol, and the npentanol are in a ratio of (0.0035-0.1) : (0.42-0.84) mL: (3-6) mL: (10-20) mL; the TEOS and the 3-CPTNIS are in a volume ratio of 10:1; and the sodium chloride and the TEOS are in a ratio of (0.0035-0.1) g: (50-250) RE; (2) synthesis of a hydroxyl-grafted material BM-011: weighing a small amount of CuC19*21-190, dispersing the CuC19*21-120 in ethanol, and adding N,N,N',N,'N"-pentamethyldiethylenetriamine (PMDETA) to obtain a mixture a; weighing an appropriate amount of ascorbic acid, and dissolving the ascorbic acid in pure water to obtain a mixture b; dispersing the base material Si-CI synthesized in the step (1) into ethanol, adding the mixture a, the mixture b, and hydroxyethyl methacrylate (HEMA) successively in a Ni atmosphere, introducing nitrogen for 5 min to 10 mm, followed by sealing to allow a reaction to occur at 25°C to 55°C; and after the reaction is completed, centrifuging to obtain a resulting precipitate, washing the resulting precipitate to obtain a resulting material, and storing the resulting material in ethanol for later use; where in the step (2), the CuC12*21420, the PMDETA, and the ascorbic acid are in a ratio of (10-50) mg (100-400) jiL (0.05-0.3) g; the base material Si-C1 and the HEMA are in a ratio of (10-50) mg: (0.5-4) mL; the CuC12*2H20 and the base material Si-C1 are in a ratio of (10-50) mg: (10-50) mg; and a ratio of a total volume of the ethanol to a volume of the pure water is larger than 10:1; (3) synthesis of a polymerizable cysteine monomer D-SH: adding a predetermined amount of L-cysteine and methacrylic anhydride (IVIAA) to a round-bottomed flask, adding a sodium hydroxide (NaOH) solution to the round-bottomed flask to obtain a resulting mixture, subjecting the resulting mixture to ultrasonic dispersion, and stirring the resulting mixture at 20°C to 35°C to allow a reaction to occur for 24 h to 50 h; and after the reaction is completed, performing extraction and evaporation with a rotary evaporator for solvent removal to obtain a yellow viscous product D-SH, and dissolving the yellow viscous product D-SH in ethanol for later use; where in the step (3), the L-cysteine, the MAA, and the NaOH solution are in a ratio of (1.23.5) g: (1-3) mL * (30-80) mL, and the NaOH solution has a concentration of 0.4 M to 0.5 M; and (4) synthesis of a nanosheet adsorbent BM-SH with high-density sites: dispersing the BM-OH prepared in the step (2) in deionized water to obtain a resulting mixture in a round-bottomed flask, weighing and dissolving ceric ammonium nitrate (CAN) in the resulting mixture in the round-bottomed flask, under a protection of a nitrogen atmosphere, adding an appropriate amount of concentrated sulfuric acid, and adding a solution of the monomer D-SH obtained in the step (3); introducing nitrogen for 5 min to 10 min, and sealing to allow a reaction to occur at 25°C to 35°C for 6 h to 15 h; and after the reaction is completed, centrifuging to obtain a resulting precipitate, and washing the resulting precipitate to obtain the BM-SH; where in the step (4), the CAN, the D-SH, and the BM-OH are in a ratio of (0.05-0.4) g: (18) mL (10-50) mg; the concentrated sulfuric acid and the deionized water are in a volume ratio of (0.5-0.7) mL: (50-70) mL; and the CAN and the concentrated sulfuric acid are in a ratio of (0.05-0.4) g: (0.5-0.7) mL The present disclosure also provides a use of a circular nanosheet with high-density sites prepared by the present disclosure in the removal of lead ions in an aqueous solution or blood. The adsorbent can reach an adsorption equilibrium within 20 min, and the adsorbent has a maximum adsorption capacity of up to 390 mg/g, and at a concentration of 0.4 mg/mL, the adsorbent can achieve a blood lead removal rate of up to 85% to normalize the blood lead level.

Synthesis of an unbranched nanosheet (Si-SH) for comparative study: mg to 50 mg of CuCl2-2H20 is weighed and dispersed in 1 mL of ethanol, and then 100 pL to 400 FL of PMDETA is added to obtain a mixture a (a ratio of the CuC12.21-120 to the PMDETA is (10-50) mg: (100-400) pL); the Si-C1 synthesized in (1) is added to 60 mL of ethanol, N2 is introduced for 2 min to 4 min, and then the mixture a and 1 mL to 8 mL of D-SH (a ratio of the DSH to the Si-C1 is (1-8) mL: (10-50) mg) are added successively in a N2 atmosphere; and nitrogen is introduced for 5 min to 10 min, and a reaction system is sealed to allow a reaction to occur at 25°C to 55°C for 10 h to 24 h, followed by centrifugation after the reaction is completed, and the resulting precipitate is washed 3 times with water and 3 times with ethanol, and then dried for later use.

Compared with the prior art, the present disclosure has the following beneficial effects.

In the present disclosure, a novel silica nanosheet adsorbent with high-density sites is prepared with a salt-containing emulsion system as a template and a branching polymerization technique as a functi onalizati on means, and is used in the removal of lead ions in an aqueous solution and blood The preparation of the nanosheet by this method also has the following advantages 1) In the present disclosure, a spherical silica capsule is prepared with a salt-containing droplet emulsion system as a template and a hydrolytic condensation product silica of an SCA as a base material, and the silica nanosheet is prepared with the characteristic that a nanoshell layer of the silica capsule is soft and easily collapsed, which provides a new method for the preparation of a nanosheet. Moreover, the surface wrinkles on the nanosheet caused by the collapse of the spherical capsule effectively avoid the site masking problem caused by the easy stacking of nanosheets.

2) The salt-containing emulsion system can be prepared through low-energy emulsification with n-pentanol as an oil phase and ethanol as a cosolvent, which involves low energy consumption and simple equipment.

3) The functionalization process based on hyperbranching polymerization increases the recognition sites on the surface of the adsorbent, and improves the adsorption capacity and adsorption rate of the adsorbent while maximizing the SSA.

4) The nanosheet is prepared with the synthesized L-cysteine monomer as a functional monomer and silica as a base material, which improves the biocompatibility of the material.

5) With a superior nanostructure and high-density functional sites, the BM-SH achieves improved adsorption rate, adsorption capacity, and selectivity, which breaks through a bottleneck of the traditional adsorbents in adsorption rate and adsorption capacity.

6) The BM-SH exhibits prominent blood compatibility and has promising application prospects in the treatment of blood lead poisoning. In summary, the construction of the nanosheet with the salt-containing emulsion system can not only increase the SSA of the material, but also reduce the time and economic costs of the material preparation; the functionalization of the material through branching polymerization can increase the functional sites on the surface of the material and improve the adsorption capacity; the regulation of surface functional groups of the adsorbent can achieve the breakthrough in the adsorption efficiency of the adsorbent; and the adsorbent of the present disclosure has high application potential in the treatment of lead-containing wastewater and the treatment of blood lead poisoning.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images (a to d) of the base material Si-C1 in (1) of Example I. FIG 2 shows atomic force microscopy (AFM) images and thickness analysis of the base material Si-C1 in (1) of Example 1, where ai shows an AFM image of the single-layer nanosheet material obtained after ultrasonication and az shows the thickness analysis of the single-layer silica nanosheet (Si-C1); and bi shows an AFM image of an intact circular nanosheet material and 1)2 shows the thickness analysis of the nanosheet.

FIG. 3 shows a hydrogen nuclear magnetic resonance (HNMR) spectrum of the product DSH in (3) of Example 1.

FIG. 4 shows the SEM images of the product Si-C1 in step (1), product BM-OH in step (2), and product BM-SH in step (4) and the SEM and mapping images of the product BM-SH in step (4) and product Si-SH in step (5) in Example 1.

FIG. 5 shows infrared (IR) spectroscopy spectra of the product Si-C1 in step (1), product BM-011 in step (2), product BM-SH in step (4), and product Si-SH in step (5) in Example I. FIG. 6 shows the results of adsorption experiments in Examples 4 to 7, where a shows the comparison of adsorption capacities of Si-SH and BM-SH at different pH values in Example 4; b shows the adsorption kinetics data and fitting curves of Si-SH and BM-SH in Example 5; c shows the adsorption equilibrium results of Si-SH and BM-SH in Example 6; and d shows the competitive adsorption performance of BM-SH for lead ions in the presence of various other ions in Example 7.

FIG. 7 shows the results of adsorption of BM-SH for blood lead in Example 8,

DETAILED DESCRIPTION OF THE EMBODIMENTS Example 1:

(1) Design and synthesis of a base material (Si-C1) 0.0085 g of NaC1 was dissolved in 0.42 mL of aqueous ammonia, then 3 mL of ethanol was added, the resulting mixture was hand-shaken and poured into a round-bottomed flask filled with 10 mL of n-pentanol, and the round-bottomed flask was hand-shaken for 30 s, and 100 jiL of TEOS and 10 RI-of 3-CPTMS were added successively, and then the round-bottomed flask was hand-shaken for thorough mixing and then placed in a water bath at 25°C to allow a reaction to occur at 80 rpm for 40 min. (2) Design and synthesis of a hydroxyl-grafted material (BM-OH) mg of copper chloride dihydrate (CuC12*2H20) was weighed and dispersed in 1 mL of ethanol, and then 150)4_, of FIVIDETA was added to obtain a mixture a. 0.1 g of ascorbic acid was weighed and dissolved in 1 mL of pure water to obtain a mixture b. 20 mg of the silica base material Si-CI synthesized in (1) was added to 50 mL of ethanol, N2 was introduced for 2 min, and the mixture a, the mixture b, and 1 mL of HEMA were added successively in a N2 atmosphere, nitrogen was introduced for 5 min, and the reaction system was sealed to allow a reaction to occur at 50°C for 10 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then stored in ethanol for later use.

(3) Design and synthesis of a polymerizable cysteine monomer 1.3 g of L-cysteine and 1 mL of NIAA were added to a round-bottomed flask, then 50 mL of a sodium hydroxide (NaOH) solution (0.5 M) was added, and the resulting mixture was subjected to ultrasonic dispersion and then placed at 25°C to allow a reaction to occur for 48 h, and after the reaction was completed, a large amount of ethyl acetate was added to the resulting mixture for extraction, the solvent was removed through evaporation with a rotary evaporator to obtain a yellow viscous liquid (D-SH), which was dissolved in 20 mL of ethanol for later use.

(4) Design and synthesis of a nanosheet adsorbent (BM-SH) with high-density sites mg of the BM-OH material prepared in (2) and 20 mL of deionized water were added to a round-bottomed flask, and after the BM-OH was thoroughly dispersed, 0.1 g of CAN was weighed and fully dissolved in the resulting mixture in the round-bottomed flask. Under the protection of a nitrogen atmosphere, 0 5 mL of concentrated sulfuric acid was added, then 2 mL of a solution of the monomer (D-SH) in ethanol obtained in (3) was added to allow a reaction to occur at 25°C for 6 h, followed by centrifugation to obtain a final product, and the final product was washed with deionized water and absolute ethanol until neutral, and then lyophilized to obtain the BM-SH.

(5) Design and synthesis of an unbranched nanosheet (Si-SH) for comparative study mg of CuCl22H20 was weighed and dispersed in 1 mL of ethanol, and then 200 pL. of PMDETA was added to obtain a mixture a. 20 mg of the Si-C1 synthesized in (1) was added to 50 mL of ethanol, N2 was introduced for 2 min to 4 min, and the mixture a and 2 mL of the monomer D-SH in (3) were added successively in a N2 atmosphere; nitrogen was introduced for 5 min, and the reaction system was sealed to allow a reaction to occur at 50°C for 10 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then lyophilized for later use.

Example 2

(1) Design and synthesis of a base material (Si-C1) 0.017 g of NaC1 was dissolved in 0 84 mL of aqueous ammonia, then 6 mL of ethanol was added, the resulting mixture was hand-shaken and poured into a round-bottomed flask filled with 20 mL of n-pentanol, and the round-bottomed flask was hand-shaken for 30 s, and 200 pi. of TEOS and 20 pt of 3-CPTMS were added successively, and then the round-bottomed flask was hand-shaken for thorough mixing and then placed in a water bath at 28°C to allow a reaction to occur at 90 rpm for 60 min (2) Design and synthesis of a hydroxyl-grafted material (BM-OH) mg of copper chloride dihydrate (CuC12*21-T20) was weighed and dispersed in 1 mL of ethanol, and then 300 pL of PMDETA was added to obtain a mixture a 0.2 g of ascorbic acid was weighed arid dissolved in 2 mL of pure water to obtain a mixture b 30 mg of the Si-C1 synthesized in (1) was added to 60 mL of ethanol, N2 was introduced for 3 min, and the mixture a, the mixture b, and 2 mL of HENIA were added successively in a N, atmosphere, nitrogen was introduced for 6 min, and the reaction system was sealed to allow a reaction to occur at 55°C for 11 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then stored in ethanol for later use.

(3) Design and synthesis of a polymerizable cysteine monomer 1.4 g of L-cysteine and I. mL of M AA were added to a 100 mL round-bottomed flask, then 60 mL of a sodium hydroxide (NaOH) solution (0.5 Ni) was added, and the resulting mixture was subjected to ultrasonic dispersion and then placed at 30°C to allow a reaction to occur for 30 h, and after the reaction was completed, a large amount of ethyl acetate was added to the resulting mixture for extraction, the solvent was removed through evaporation with a rotary evaporator to obtain a yellow viscous product (D-SH), which was dissolved in 20 mL of ethanol for later use.

(4) Design and synthesis of a nanosheet adsorbent (BM-SH) with high-density sites mg of the BM-OH material prepared in (2) and 70 mL of deionized water were added to a round-bottomed flask, and after the BM-OH was thoroughly dispersed, 0.2 g of CAN was weighed and fully dissolved in the resulting mixture in the round-bottomed flask. Nitrogen was introduced, and under the protection of a nitrogen atmosphere, 0 7 mL of concentrated sulfuric acid was added, and then 4 mL of a solution of the monomer (D-SH) obtained in (3) was added. Nitrogen was introduced for 6 min, the reaction system was sealed to allow a reaction to occur at 30°C for 5 h, followed by centrifugation to obtain a final product, and the final product was washed with deionized water and absolute ethanol until neutral, and then centrifuged and washed, and lyophilized to obtain a solid BM-SH.

(5) Design and synthesis of an unbranched nanosheet (Si-SH) for comparative study mg of CuC12.21-120 was weighed and dispersed in 1 mL of ethanol, and then 300 RI_ of PIVIDETA was added to obtain a mixture a. 30 mg of the Si-C1 synthesized in (1) was added to 60 mL of ethanol, N2 was introduced for 3 min, and the mixture a and 4 mL of the solution of the monomer (D-SH) in (3) were added successively in a N, atmosphere, nitrogen was introduced for 6 min, and the reaction system was sealed to allow a reaction to occur at 55°C for 11 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then lyophilized for later use.

Example 3

(1) Design and synthesis of a base material (Si-C1) 0.007 g of NaC1 was dissolved in 0.50 mL of aqueous ammonia, then 3 mL of ethanol was added, the resulting mixture was hand-shaken and poured into a round-bottomed flask filled with 10 mL of n-pentanol, and the round-bottomed flask was hand-shaken for 40 s, and 100 pL of TEOS and 10 pL of 3-CPTMS were added successively, and then the round-bottomed flask was hand-shaken for thorough mixing and then placed in a water bath at 30°C to allow a reaction to occur at 60 rpm for 180 min. (2) Design and synthesis of a hydroxyl-grafted material (BM-OH) mg of copper chloride dihydrate (CuC1)*2H)0) was weighed and dispersed in 1 mL of ethanol, and then 400 [IL of PMDETA was added to obtain a mixture a. 0.3 g of ascorbic acid was weighed and dissolved in 3 mL of pure water to obtain a mixture b. 50 mg of the Si-C1 synthesized in (1) was added to 70 mL of ethanol, N2 was introduced for 2 min to 4 min, and the mixture a, the mixture b, and 4 mL of HEMA were added successively in a N2 atmosphere, nitrogen was introduced for 8 min, and the reaction system was sealed to allow a reaction to occur at 45°C for 15 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then stored in ethanol for later use.

(3) Design and synthesis of a polymerizable cysteine monomer 2 g of L-cysteine and 1.7 mL of MAA were added to a round-bottomed flask, then 80 mL of a sodium hydroxide (NaOH) solution (0.5 M) was added, and the resulting mixture was subjected to ultrasonic dispersion and then placed at 35°C to allow a reaction to occur for 50 h, and after the reaction was completed, a large amount of ethyl acetate was added to the resulting mixture for extraction, the solvent was removed through evaporation with a rotary evaporator to obtain a yellow viscous product (D-SH), which was dissolved in 20 mL of ethanol.

(4) Design and synthesis of a nanosheet adsorbent (BM-SH) with high-density sites mg of the BM-OH material prepared in (2) and 60 mL of deionized water were added to a round-bottomed flask, and after the BM-OH was thoroughly dispersed, 0.4 g of CAN was weighed and fully dissolved in the resulting mixture in the round-bottomed flask. Under the protection of a nitrogen atmosphere, 0 6 mL of concentrated sulfuric acid was added, and then 8 mL of a solution of the monomer (D-SH) obtained in (3) was added. Nitrogen was introduced for 5 min, the reaction system was sealed to allow a reaction to occur at 35°C for 15 h, followed by centrifugation to obtain a final product, and the final product was washed with deionized water and absolute ethanol until neutral, and then centrifuged and lyophilized to obtain a solid BM-SH for later use.

(5) Design and synthesis of an unbranched nanosheet (Si-SH) for comparative study mg of CuC12'2H20 was weighed and dispersed in 1 mL of ethanol, and then 400 [IL of PMDETA was added to obtain a mixture a. 50 mg of the Si-C1 synthesized in (1) was added to 60 mL of ethanol, N2 was introduced for 3 min, and the mixture a and 8 mL of the D-SH were added successively in a N, atmosphere, nitrogen was introduced for 5 mm, and the reaction system was sealed to allow a reaction to occur at 45°C for 12 h, followed by centrifugation after the reaction was completed, and the resulting precipitate was washed three times with water and three times with ethanol, and then lyophilized for later use.

Example 4

The BM-SH and Si-SH prepared under the conditions described in Example 1 (2 mg) were individually added to 2 mL of each of lead ion solutions with initial pH values of 3, 4, 5, and 6 (concentration: 100 mg/E), the resulting mixtures were placed in a 25°C water bath shaker for 6 h, and the lead ion concentration in the final solution was determined through graphite furnace atomic absorption spectrometry (GFAAS). Three parallel experiments were conducted.

Example 5

2 mg of the BM-SH and 2 mg of the Si-SH were accurately weighed and respectively added to 3 mL of a lead ion solution (250 mg/L) and 2 mL of a lead ion solution (100 mg/L), the resulting mixtures were placed in a 25°C water bath shaker, and an adsorption solution was collected at intervals of 5 min, 10 min, 20 min, 40 min, 60 min, 120 mm, and 240 min. Three parallel experiments were conducted. The residual lead ion concentration was determined through GFAAS.

Example 6

6 samples of BM-SH (2 mg) were accurately weighed and respectively added to lead ion solutions (3 mL) with concentrations of 100 mg/L, 150 mg/L, 200 mg/L, 250 mg/L, 300 mg/L, and 350 mg/E, the resulting mixtures were placed in a 25°C water bath shaker for 3 h, and adsorption solutions were collected, and the residual lead ion concentration was determined through GFAAS. 6 samples of the Si-SH (2 mg) were accurately weighed and respectively added to lead ion solutions (2 mL) with concentrations of 50 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, 250 mg/L, and 300 mg/L, the resulting mixtures were placed in a 25°C water bath shaker for 3 h, and adsorption solutions were collected, where three parallel experiments were conducted and the residual lead ion concentration was determined through GFAAS.

Example 7

2 mg of the BM-SH was accurately weighed and added to 10 mL of a mixed solution (100 mg/L) with Ph', IC, Nat Ca', and Mg', the resulting mixture was placed in a 25°C water bath shaker for 1 h and then centrifuged to obtain a supernatant, and the lead ion concentration was determined by an inductively coupled plasma-atomic emission spectrometer (ICP-AES).

Example 8

Five groups of anticoagulated blood samples (1 mL) were taken and diluted twice with normal saline (NS), where one group was used as a blank group, and the remaining 4 groups were each added to a lead-containing solution to prepare 4 groups of lead-containing blood samples with lead concentrations of 100 kg/L, 200 jig/L, 400 jigiL, and 600 itg/L, followed by incubation at 37°C for 1 h to obtain lead-contaminated blood samples, 0.8 mg of BM-SH was added to each of the lead-contaminated blood samples, and the resulting mixture was thoroughly mixed, and allowed to stand at 37°C for 1 h, and centrifuged at 2,000 rpm for 20 min, and 1 mL of the resulting supernatant was taken, and subjected to high-temperature and high-pressure digestion, and tested by ICP-AES for the lead ion concentration. Three parallel experiments were conducted to collect data.

FIG. 1 shows SEM and TEM images (a to d) of the base material Si-C1 in (1) of Example 1, where a and b are SEM images, and it can be seen that the material has a circular shape, a flaky structure, and surface wrinkles caused by collapse; and c and d are TEM images, and it can also be seen that the material has a circular shape, a wrinkled structure, and an extremely small thickness.

FIG. 2 shows AFM images and thickness analysis of the base material Si-C1 in (1) of Example 1, where al shows the single-layer nanosheet material obtained after ultrasonication and az shows the thickness analysis of the single-layer silica nanosheet (Si-CD, and it can be seen that a nanosheet monolayer has a thickness of about 12 nm; and b1 shows an intact circular nanosheet material and bz shows the thickness analysis of the nanosheet, and it can be seen that the nanosheet adsorbent has a double-layer structure, surface wrinkles, and an overall thickness of about 30 nm.

FIG. 3 shows an HNNIR spectrum of the product D-SH in (3) of Example 1, and it can be seen from the HNMR spectrum that the polymerizable monomer is successfully synthesized.

FIG. 4 shows the SEM images of the product Si-C1 in (1), product BM-OH in (2), and product BM-SH in (4), and the SEM and mapping images of the product BM-SH in (4) and product Si-SH in (5) in Example 1. It can be seen that, after the branching modification and functional group grafting, the material still retains a roughly circular shape and a nanoscale thickness, and fine particles on the surface of the material become larger polymers. It can be seen from the mapping image that there are a large amount of S and N on the product BM-SH in (4), while there is a relatively small amount of S and N on the product Si-SH in (5), indicating that the cysteine monomer is successfully gaffed to the surface of the material and the BM-SH has a relatively high density of recognition sites.

FIG. 5 shows IR spectroscopy spectra of the product Si-C1 in (1), product BM-OH in (2), product BM-S1 in (4), and product Si-SH in (5) in Example I. The changes of surface functional groups of the three materials indicate that the materials are successfully prepared and the cysteine monomer is successfully grafted to the surface of the base material.

FIG. 6 shows the results of adsorption experiments in Examples 4 to 7, where a shows the comparison of adsorption capacities of Si-SH and BM-SH at different pH values in Example 4, and it can be seen that an adsorption capacity of Si-SH is always smaller than an adsorption capacity of BM-SH, and both achieve the optimal adsorption effect at a pH of 6; b shows the adsorption kinetics data and fitting curves of Si-SH and BM-SH in Example 5, and it can be seen that BM-SH has a high adsorption rate, can achieve an adsorption equilibrium within 20 mm, and exhibits a better adsorption efficiency than Si-SH; c shows the adsorption equilibrium results of Si-SH and BM-SH in Example 6, and it can be seen that BM-SH has a higher adsorption capacity than Si-SH, which is much higher than adsorption capacities of the reported adsorbents, and d shows the competitive adsorption performance of BM-SH for lead ions in the presence of various other ions in Example 7, and it can be seen that BM-S1-1 exhibits prominent adsorption performance for lead ions.

FIG. 7 shows the results of adsorption of BM-SH for blood lead in Example 8, and it can be seen that BM-SH has promising application prospects in the blood lead removal, and has a removal rate of higher than 80%.

Claims

CLAIMSWHAT IS CLAIMED IS: I. A preparation method of a circular nanosheet with high-density sites, comprising the following steps: (1) synthesis of a base material Si-Cl: dissolving sodium chloride (NaC1) in a predetermined amount of aqueous ammonia, adding an appropriate amount of ethanol, followed by hand-shaking for thorough mixing to obtain a resulting mixture; pouring the resulting mixture into a round-bottomed flask filled with n-pentanol, hand-shaking the round-bottomed flask for 30 s to 60 s, adding tetraethyl orthosilicate (fLOS) and 3-chloropropyltrimethoxysilane (3-CPTMS) successively to the round-bottomed flask, handshaking the round-bottomed flask for thorough mixing, and placing the round-bottomed flask in a water bath at a predetermined temperature to allow a reaction to occur at a low rotational speed for 20 min to 180 min; (2) synthesis of a hydroxyl-grafted material BM-OH: weighing a small amount of CuC12-2H20, dispersing the CuC12-2H20 in ethanol, and adding N,N,N',N,'N"-pentamethyldiethylenetriamine (PMDETA) to obtain a mixture a; weighing an appropriate amount of ascorbic acid, and dissolving the ascorbic acid in pure water to obtain a mixture b; dispersing the base material Si-C1 synthesized in the step (1) into ethanol, adding the mixture a, the mixture b, and hydroxyethyl methacrylate (HEMA) successively in a N2 atmosphere, introducing nitrogen, followed by sealing to allow a reaction to occur at a predetermined temperature; and after the reaction is completed, centrifuging to obtain a resulting precipitate, washing the resulting precipitate to obtain a resulting material, and storing the resulting material in ethanol for later use; (3) synthesis of a polymerizable cysteine monomer D-SH: adding a predetermined amount of L-cysteine and methacrylic anhydride (MAA) to a round-bottomed flask, adding a sodium hydroxide (NaOH) solution to the round-bottomed flask to obtain a resulting mixture, subjecting the resulting mixture to ultrasonic dispersion, and stirring the resulting mixture at 20°C to 35°C to allow a reaction to occur for 24 h to 50 h; and after the reaction is completed, performing extraction and evaporation with a rotary evaporator for solvent removal to obtain a yellow viscous product D-SH, and dissolving the yellow viscous product D-SH in ethanol for later use; and (4) synthesis of a nanosheet adsorbent BM-SH with high-density sites: dispersing the BM-OH prepared in the step (2) in deionized water to obtain a resulting mixture in a round-bottomed flask, weighing and dissolving eerie ammonium nitrate (CAN) in the resulting mixture in the round-bottomed flask, under a protection of a nitrogen atmosphere, adding an appropriate amount of concentrated sulfuric acid, and adding a solution of the monomer D-SH obtained in the step (3); introducing nitrogen, and sealing to allow a reaction to occur at a predetermined temperature; and after the reaction is completed, centrifuging to obtain a resulting precipitate, and washing the resulting precipitate to obtain the BM-SF-1.
2. The preparation method according to claim 1, wherein in the step (1), the sodium chloride, the aqueous ammonia, the ethanol, and the n-pentanol are in a ratio of (0.0035-0.1) g: (0.42-0.84) mL: (3-6) mL: (10-20) mL; the TEOS and the 3-CPTMS are in a volume ratio of 10:1; and the sodium chloride and the IEOS are in a ratio of (0.0035-0.1) g: (50-250) uL.
3. The preparation method according to claim 1, wherein in the step (1), the water bath has a temperature of 25°C to 30°C, and the reaction is allowed to occur at a rotational speed of 20 rpm to 200 rpm.
4. The preparation method according to claim 1, wherein in the step (2), the CuC12.2H20, the PMDETA, and the ascorbic acid are in a ratio of (10-50) mg: (100-400) RI, * (0.05-0.3) g; the base material Si-C1 and the HEMA are in a ratio of (10-50) mg: (0.5-4) mL; and the CuC12.21-120 and the base material Si-CI are in a ratio of (10-50) mg: (10-50) mg.
5. The preparation method according to claim 1, wherein in the step (2), a ratio of a total volume of the ethanol to a volume of the pure water is larger than 10:1; the nitrogen is introduced for 5 min to 10 min; and the reaction is allowed to occur at 25°C to 55°C.
6. The preparation method according to claim 1, wherein in the step (3), the L-cysteine, the MAA, and the NaOH solution are in a ratio of (1.2-3.5) g: (1-3) mL (30-80) mL; and the NaOH solution has a concentration of 0.4 M to 0.5 NI.
7. The preparation method according to claim 1, wherein in the step (4), the CAN, the D-SH, and the BM-OH are in a ratio of (0.05-0.4) g: (1-8) mL * (10-50) mg; the concentrated sulfuric acid and the deionized water are in a volume ratio of (0.5-0.7) mL * (50-70) mL; and the CAN and the concentrated sulfuric acid are in a ratio of (0.05-0.4)8: (0.5-0.7) mL.
8. The preparation method according to claim 1, wherein in the step (4), the nitrogen is introduced for 5 min to 10 min; and the reaction is allowed to occur at 25°C to 35°C for oh to 15 9 A use of a circular nanosheet with high-density sites prepared by the preparation method according to any one of claims 1 to 8 in the removal of lead ions in an aqueous solution or blood