Attapulgite nano fluorescent probe for double-ion detection and preparation method of attapulgite nano fluorescent probe

Abstract

The invention discloses an attapulgite nano fluorescent probe for double-ion detection and a preparation method thereof, the method comprises the following steps: firstly, introducing a tertiary amine group on the surface of attapulgite by using a siloxane coupling agent, and then carrying out quaternization reaction on the modified attapulgite and 5-chloromethyl salicylaldehyde to obtain the attapulgite nano fluorescent probe for double-ion detection. And finally, through a Schiff base condensation reaction, pyridine formylhydrazine is grafted to obtain the salicylhydrazone functionalized attapulgite nano material. The salicylhydrazone group on the surface of the material is used as a fluorescence response site, shows a fluorescence enhancement effect when being combined with Al (III) in a water medium, generates fluorescence quenching when being combined with Cu (II), and has high selectivity to various coexisting ions, so that the probe material can be used for fluorescence detection of two metal ions, namely Al (III) and Cu (II) in water, and has a good application prospect. Meanwhile, the probe material can synchronously remove target metal ions in a water body through an adsorption effect, and a new strategy is provided for developing a multifunctional nano fluorescent probe.

Description

Technical Field

[0001] The present invention relates to the field of surface organic functionalization modification of natural clay, and in particular to an attapulgite nano fluorescent probe for dual ion detection and a preparation method thereof, which realizes the fluorescence detection of two metal ions, Al(III) and Cu(II), in water. Background Art

[0002] As a highly sensitive and selective detection tool, fluorescent probes have important applications in environmental monitoring and bioanalysis. Al(III) and Cu(II) are widely present metal ion pollutants in the environment, and their excessive presence can cause serious harm to ecosystems and human health. The accumulation of Al(III) is closely associated with neurodegenerative diseases, while excessive exposure to Cu(II) may cause liver damage and oxidative stress. Therefore, the development of fluorescent probe technologies that can simultaneously detect and remove these two ions has become a current research hotspot.

[0003] Although traditional small molecule fluorescent probes have the advantages of diversity, adjustable structure, sensitive response, and high specificity, they have certain defects in practical applications. First, most small molecule probes are highly hydrophobic and cannot be directly dissolved in aqueous solutions. Fluorescence detection requires the use of organic solvents such as methanol, acetonitrile, and tetrahydrofuran. The use of these organic solvents not only increases the complexity of the operation, but also causes a certain degree of environmental pollution. Secondly, such probes are usually used in a "disposable" manner and cannot be recycled and reused, resulting in increased detection costs.

[0004] In recent years, organic-inorganic hybrid nanofluorescent probes have been developed by covalently immobilizing fluorescent groups on the surface of inorganic nanocarriers to construct composite probe systems that combine molecular recognition functions with nanomaterial properties. Through the strategy of surface modification stabilizers, the nanoprobes can maintain long-term stable dispersion in the aqueous phase, realizing a completely water-soluble detection system. Secondly, based on the solid-phase support properties of the nanocarriers, the probe material can be quickly recovered and reused through simple filtration / centrifugation. While completing fluorescence detection, the material can also simultaneously remove target ions from the aqueous phase through separation and recovery, realizing the dual functional integration of detection and removal.

[0005] Attapulgite is a naturally occurring hydrous magnesium-aluminum silicate clay mineral with a unique nanorod-like crystal structure and layered characteristics. As a typical fibrous silicate material, its surface is rich in reactive hydroxyl groups, providing ideal reaction sites for surface chemical modification. Of particular note, the absence of fluorescence in the material itself makes it an ideal support material for the construction of fluorescent probes.

[0006] Hydrazone compounds are an important class of organic compounds, characterized by the characteristic –NH–N=CH– functional group in their molecular structure. They have broad applications in medicinal chemistry, dynamic combinatorial chemistry, covalent organic frameworks, and organic optical materials. Aromatic hydrazone compounds, due to their excellent coordination ability and large conjugated system, are particularly suitable as fluorescent probes for the detection of metal ions and other molecules. In this study, a salicylic hydrazone fluorescent chromophore was covalently attached to the surface of attapulgite via a quaternary ammonium group, successfully preparing a highly water-dispersible attapulgite nanofluorescent probe material. The surface-modified salicylic hydrazone groups act as fluorescent response sites, exhibiting fluorescence enhancement when bound to Al(III) in aqueous media, while fluorescence quenching occurs when bound to Cu(II). This dual-responsiveness makes this material promising for the detection and removal of heavy metal ions in wastewater. Summary of the Invention

[0007] In view of the limited applicability of small molecule fluorescent probes for detecting target metal ions in the existing technology, the present invention provides a attapulgite nano fluorescent probe for dual ion detection and a preparation method thereof. The surface of the attapulgite material is loaded with quaternary ammonium salt ions and salicylic hydrazone fluorescent chromophores to achieve fluorescent detection of two metal ions, Al(III) and Cu(II), in water. The general structural formula is as follows:

[0008]

[0009] in, It refers to attapulgite nanorod-shaped crystals, where n is an integer of 1 or 2, Q is a methyl group or an ethyl group, R is a hydrogen atom or a methyl group, and the R substitution position is one of the four substitution sites on the benzene ring.

[0010] Step 1. The attapulgite raw material ATP is first passed through a 200-mesh sieve to remove larger particles. After washing with deionized water, 0.15 mol / L HCl solution is added and mechanically stirred overnight. Then, it is washed with deionized water several times until neutral, dried and ground for use. The pretreated attapulgite is dispersed in an organic solvent, and a silane coupling agent containing a tertiary amino group is added. The reaction is heated at 60 to 80 ° C under nitrogen protection for 12 to 36 hours. After the reaction mixture is cooled, it is filtered, washed with ethanol three times, and dried in a vacuum oven at 60 ° C overnight to obtain attapulgite ATP-DATMS with a surface modified with a tertiary amino group. The reaction formula of the above synthesis steps is expressed as follows:

[0011]

[0012] Step 2: Add the ATP-DATMS prepared in step 1 to an organic solution containing 5-chloromethyl salicylaldehyde, disperse by ultrasonication, and stir at room temperature for 12 to 48 hours. After the reaction is complete, collect the product by centrifugation, wash it three times with ethanol, and finally dry it in a vacuum oven at 60°C overnight to obtain attapulgite ATP-CAS with salicylaldehyde grafted on its surface. The reaction formula of the above synthesis steps is expressed as follows:

[0013]

[0014] Step 3: Add the ATP-CAS and picolinyl hydrazide prepared in step 2 to an organic solvent, ultrasonically disperse, and react at 25-60° C. with stirring for 8-24 hours. After the reaction is completed, separate the product by centrifugation, wash it three times with ethanol, and finally dry it in a vacuum oven at 60° C. overnight to obtain attapulgite ATP-BDNOL modified with a salicylic hydrazone fluorescent chromophore. The above synthesis steps are expressed as follows:

[0015]

[0016] As a preferred technical solution of the present invention, the solid-liquid mass volume ratio of the attapulgite after sieving and removing impurities in step 1 to 0.15 mol / L hydrochloric acid solution is 1:30~60 g / mL; the organic solvent is one of dichloromethane, chloroform, isopropyl alcohol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the solid-liquid mass volume ratio of the activated attapulgite and the organic solvent ... The mass-to-volume ratio is 1:50-100 g / mL; the tertiary amino group-containing silane coupling agent is selected from any one of (N,N-dimethyl-3-aminopropyl)trimethoxysilane, (N,N-diethyl-3-aminopropyl)trimethoxysilane, (N,N-dimethyl-4-aminobutyl)trimethoxysilane, and (N,N-diethyl-4-aminobutyl)trimethoxysilane; and the mass of the tertiary amino group-containing silane coupling agent is 0.5 to 2 times the mass of the activated attapulgite.

[0017] As a preferred technical solution of the present invention, the organic solvent in step 2 is one of dichloromethane, chloroform, isopropanol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the solid-liquid mass volume ratio of the surface-modified tertiary amine group-attapulgite ATP-DATMS and the organic solvent is 1:50~80g / mL; the amount of the 5-chloromethyl salicylaldehyde and the mass ratio of the tertiary amine group-modified attapulgite material ATP-DATMS is 1:0.5~2.

[0018] As a preferred technical solution of the present invention, the organic solvent in step three is one of dichloromethane, chloroform, isopropanol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the pyridine carboxylic acid hydrazide is selected from 2-pyridine carboxylic acid hydrazide, 3-methyl-2-pyridine carboxylic acid hydrazide, 4-methyl-2-pyridine carboxylic acid hydrazide, 5-methyl-2-pyridine carboxylic acid hydrazide or 6-methyl-2-pyridine carboxylic acid hydrazide; the solid-liquid mass volume ratio of the tertiary amine-modified attapulgite material ATP-DATMS to the organic solvent is 1:50~80g / mL; the mass ratio of the amount of the pyridine carboxylic acid hydrazide to the salicylaldehyde-modified attapulgite material ATP-CAS is 1:0.5~2.

[0019] The attapulgite nano-fluorescent probe for dual ion detection according to claim 1 is characterized in that: the surface of the attapulgite nano-fluorescent probe is modified with a salicylic hydrazone group as a fluorescent response site, and exhibits a fluorescence enhancement effect when combined with Al(III) in an aqueous medium, and a fluorescence quenching phenomenon occurs when combined with Cu(II). The probe exhibits high selectivity for a variety of coexisting ions and can therefore be used for fluorescence detection of two metal ions, Al(III) and Cu(II), in water bodies; at the same time, the material can simultaneously remove Al(III) and Cu(II) ions in water bodies through adsorption.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The matrix uses natural attapulgite nanomaterials, which are abundant and low-cost. Its unique rod-like crystal structure and surface hydroxyl groups make it easy to chemically modify, and its low absorption / emission properties in the visible spectrum avoid fluorescence interference during detection.

[0022] 2. Innovative surface modification with a salicylic hydrazone moiety enables bifunctional detection. Fluorescence is enhanced when the salicylic hydrazone moiety binds to Al(III) and quenched when it binds to Cu(II). This probe exhibits excellent selectivity for target ions and is suitable for metal ion detection in complex aqueous environments.

[0023] 3. The probe is synthesized via a stepwise surface chemical modification method, resulting in a simple preparation process. A salicylaldehyde Schiff base ligand is anchored to the surface of attapulgite nanorod-shaped crystals via a quaternary ammonium group. The hydrophilicity of the quaternary ammonium salt enables stable dispersion in water, enabling direct detection in pure water systems without the addition of organic solvents.

[0024] 4. The probe material also has separation and recovery capabilities. After detection, solid-liquid separation can be achieved through simple filtration / centrifugation and reused after elution. This property also allows it to be used for the separation, enrichment, and recovery of metal ions, offering multiple applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 Transmission electron micrographs of (a, b) attapulgite raw material ATP and (c, d) ATP-BDNOL-1 prepared in Example 1;

[0027] Figure 2 Fourier transform infrared spectra of ATP-BDNOL-1 prepared in Example 1 at various stages of synthesis;

[0028] Figure 3 Changes in fluorescence emission spectra of the suspension of ATP-BDNOL-1 prepared in Example 1 in the presence of different concentrations of (a) Al(III) and (b) Cu(II);

[0029] Figure 4 The fluorescence emission spectra of the suspension of ATP-BDNOL-1 prepared in Example 1 in the presence of different metal ions;

[0030] Figure 5 The adsorption capacity of ATP-BDNOL-1 prepared in Example 1 for Al(III) and Cu(II) at different pH values. DETAILED DESCRIPTION

[0031] To further disclose the technical solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] Example 1:

[0033] The preparation of a attapulgite nanofluorescent probe ATP-BDNOL-1 for dual ion detection is as follows:

[0034] (1) 2.00 g of attapulgite raw material ATP was first passed through a 200-mesh sieve to remove larger particles, washed with deionized water, added with 90 mL of 0.15 mol / L HCl solution and mechanically stirred overnight, then washed with deionized water several times until neutral, dried and ground for use, 1.00 g of pretreated attapulgite was dispersed in 100 mL of toluene, 1.00 g of (N, N-dimethyl-3-aminopropyl) trimethoxysilane was added, and heated at 80 ° C under nitrogen protection for 24 hours. After the reaction mixture was cooled, it was filtered, washed with ethanol three times, and dried in a vacuum oven at 60 ° C overnight to obtain attapulgite ATP-DATMS-1 with surface modified tertiary amino groups.

[0035] (2) 1.00 g of ATP-DATMS-1 prepared in step 1 was added to 60 mL of anhydrous acetonitrile solution containing 2.00 g of 5-chloromethyl salicylaldehyde, and the mixture was ultrasonically dispersed and stirred at room temperature for 24 hours. After the reaction was completed, the product was collected by centrifugation and washed three times with ethanol. Finally, it was dried in a vacuum oven at 60°C overnight to obtain attapulgite ATP-CAS-1 with salicylaldehyde grafted on its surface.

[0036] (3) 1.00 g of ATP-CAS-1 and 1.00 g of picolinyl hydrazide prepared in step 2 were added to 50 mL of methanol, and after ultrasonic dispersion, the mixture was stirred and reacted at 25 ° C for 24 hours. After the reaction was completed, the product was separated by centrifugation, washed with ethanol three times, and finally dried in a vacuum oven at 60 ° C overnight to obtain salicylic hydrazone fluorescent chromophore-modified attapulgite ATP-BDNOL-1. The structural schematic diagram of the final product is as follows:

[0037]

[0038] Example 2:

[0039] The preparation of a attapulgite nanofluorescent probe ATP-BDNOL-2 for dual ion detection is as follows:

[0040] (1) 2.00 g of attapulgite raw material ATP was first passed through a 200-mesh sieve to remove larger particles, washed with deionized water, added with 60 mL of 0.15 mol / L HCl solution and mechanically stirred overnight, then washed with deionized water several times until neutral, dried and ground for use, 1.00 g of pretreated attapulgite was dispersed in 70 mL of ethanol, 0.50 g of (N,N-diethyl-3-aminopropyl)trimethoxysilane was added, and heated at 70 ° C under nitrogen protection for 12 hours. After the reaction mixture was cooled, it was filtered, washed with ethanol three times, and dried in a vacuum oven at 60 ° C overnight to obtain attapulgite ATP-DATMS-2 with surface modified tertiary amino groups.

[0041] (2) 1.00 g of ATP-DATMS-2 prepared in step 1 was added to 80 mL of a dioxane solution containing 0.50 g of 5-chloromethyl salicylaldehyde, and the mixture was ultrasonically dispersed and stirred at room temperature for 12 hours. After the reaction was completed, the product was collected by centrifugation and washed three times with ethanol. Finally, the product was dried in a vacuum oven at 60°C overnight to obtain attapulgite ATP-CAS-2 with salicylaldehyde grafted on its surface.

[0042] (3) 1.00 g of ATP-CAS-2 prepared in step 2 and 0.50 g of 3-methyl-2-pyridinecarboxylic acid hydrazide were added to 80 mL of tetrahydrofuran, and after ultrasonic dispersion, the mixture was stirred and reacted at 40 ° C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed with ethanol three times, and finally dried in a vacuum oven at 60 ° C overnight to obtain salicylic hydrazone fluorescent chromophore-modified attapulgite ATP-BDNOL-2. The structural schematic diagram of the final product is as follows:

[0043]

[0044] Example 3:

[0045] The preparation of a attapulgite nanofluorescent probe ATP-BDNOL-3 for dual ion detection is as follows:

[0046] (1) 2.00 g of attapulgite raw material ATP was first passed through a 200-mesh sieve to remove larger particles, washed with deionized water, added with 120 mL of 0.15 mol / L HCl solution and mechanically stirred overnight, then washed with deionized water several times until neutral, dried and ground for use, 1.00 g of pretreated attapulgite was dispersed in 50 mL of dioxane, 2.00 g of (N,N-dimethyl-4-aminobutyl)trimethoxysilane was added, and heated at 60 ° C under nitrogen protection for 36 hours. After the reaction mixture was cooled, it was filtered, washed with ethanol three times, and dried in a vacuum oven at 60 ° C overnight to obtain attapulgite ATP-DATMS-3 with surface modified tertiary amino groups.

[0047] (2) 1.00 g of ATP-DATMS-2 prepared in step 1 was added to 50 mL of tetrahydrofuran solution containing 1.00 g of 5-chloromethyl salicylaldehyde, and after ultrasonic dispersion, the mixture was stirred at room temperature for 48 hours. After the reaction was completed, the product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum oven at 60°C overnight to obtain attapulgite ATP-CAS-3 with salicylaldehyde grafted on the surface.

[0048] (3) 1.00 g of ATP-CAS-3 prepared in step 2 and 2.00 g of 5-methyl-2-pyridinecarboxylic acid hydrazide were added to 50 mL of ethanol, and after ultrasonic dispersion, the mixture was stirred and reacted at 60 ° C for 8 hours. After the reaction was completed, the product was separated by centrifugation, washed with ethanol three times, and finally dried in a vacuum oven at 60 ° C overnight to obtain salicylic hydrazone fluorescent chromophore-modified attapulgite ATP-BDNOL-3. The structural schematic diagram of the final product is as follows:

[0049]

[0050] Example 4:

[0051] The attapulgite nano fluorescent probe ATP-BDNOL-1 for dual ion detection obtained in Example 1 was characterized by transmission electron microscopy. Figure 1 Comparison of the medium-sized attapulgite raw materials ATP and ATP-BDNOL-1 shows that surface modification significantly restructures the micromorphology of the attapulgite. The raw ATP exhibits disordered, stacked, blocky aggregates with a wide particle size distribution (0.5 to 1.2 μm) and distinct adhesion interfaces between the layers. However, after mechanical grinding, acid washing, and chemical modification, ATP-BDNOL-1 exhibits a directional, fibrous network structure. This change is due to the grinding and acid etching breaking up the aggregate structure of the attapulgite. After loading the attapulgite material with quaternary ammonium ions and salicylic hydrazone fluorescent chromophores, the material surface becomes positively charged and has good dispersibility in water, resulting in improved dispersibility in transmission electron microscopy images.

[0052] Example 5:

[0053] The spectrum changes during the synthesis of the attapulgite nanofluorescent probe ATP-BDNOL-1 for dual ion detection obtained in Example 1 were characterized by Fourier transform infrared spectroscopy. Fourier transform infrared spectroscopy can generally be used to study the composition and qualitative analysis of substances and can reflect the changes in organic groups in each synthesis step. The infrared spectra of the attapulgite raw materials ATP, ATP-DATMS-1, ATP-CAS-1, and ATP-BDNOL-1 are shown in Figure 1. Figure 2 As shown. For ATP, at 683 cm -1 and 789cm -1 The energy bands at 1030cm are the bending vibration absorption peak of Si-O-Si and the vibration absorption peak of Si-O. -1 The energy band at 3420 cm is the asymmetric stretching vibration absorption peak of the non-internal silicon of the silicon-oxygen bond. -1 Stretching vibrations belonging to Al-OH and Mg-OH were observed at 2979 cm -1 and 2850cm-1 The new peak at 1477 cm corresponds to the asymmetric and symmetric stretching vibrations of CH. -1 The peak near 1641cm in ATP-CAS is probably due to the vibration of -CH2-. -1 The peak can be attributed to the C=O group in salicylaldehyde. However, this peak in ATP-BDNOL-1 almost disappears, indicating that the C=O group on salicylaldehyde reacts with picolinylhydrazide and is consumed. This result indicates that ATP-BDNOL-1 was successfully synthesized.

[0054] Example 6:

[0055] The present invention studies the fluorescence response of ATP-BDNOL-1, a nano-fluorescent probe of attapulgite for dual ion detection obtained in Example 1, to different concentrations of Al(III) and Cu(II). Specifically, the experiment was carried out at 25°C. 2.0 mL of Al(III) or Cu(II) solution of different concentrations was added to 2.0 mL of ATP-BDNOL-1 stock dispersion (concentration of 0.2 mg / mL). After mixing, the concentration of ATP-BDNOL-1 became 0.1 mg / mL. Subsequently, the pH value of the solution was adjusted to 6.0, and ultrasonic oscillation was used to achieve full dispersion. Subsequently, the dispersion was quickly transferred to a quartz cuvette to record its fluorescence emission spectrum at an excitation wavelength of 390 nm.

[0056] like Figure 3 As shown in Figure a, as the Al(III) concentration in the ATP-BDNOL-1 suspension gradually increased from 0 mg / L to 2.0 mg / L, the fluorescence intensity of ATP-BDNOL-1 showed a clear upward trend. During this process, the fluorescence intensity at 475 nm continued to increase, and the shape of the fluorescence emission curve remained stable in the presence of Al(III). This change can be used as an effective reference indicator to measure the changes in fluorescence enhancement caused by Al(III). Figure 3As shown in Figure b, as the Cu(II) concentration in the ATP-BDNOL-1 suspension gradually increased from 0 mg / L to 2.0 mg / L, the fluorescence intensity of ATP-BDNOL-1 continued to decrease. This downward trend was particularly significant at 475 nm, and the shape of the fluorescence curve remained roughly consistent throughout the entire process of fluorescence intensity decrease. When the Cu(II) concentration reached 2.0 mg / L, the fluorescence intensity at 475 nm dropped to a minimum. Thereafter, as the Cu(II) concentration continued to increase, the shape of the fluorescence spectrum and the trend of fluorescence intensity decrease no longer changed. This unique fluorescence response characteristic to Al(III) and Cu(II) makes ATP-BDNOL-1 show potential application value in the field of ion detection. Therefore, ATP-BDNOL-1 can be used as an effective fluorescence detection probe for Al(III) and Cu(II).

[0057] Example 7:

[0058] The present invention studies the fluorescence response of ATP-BDNOL-1, a nano-fluorescent probe of attapulgite for dual ion detection obtained in Example 1, to different metal ions. Specifically, the experiment was carried out at 25°C. 2.0 mL of 4.0 mg / L different metal ion solutions were added to 2.0 mL of ATP-BDNOL-1 stock dispersion (concentration of 0.2 mg / mL). After mixing, the concentration of ATP-BDNOL-1 became 0.1 mg / mL and the metal ion concentration became 2.0 mg / L. Subsequently, the pH value of the solution was adjusted to 6.0, and ultrasonic oscillation was used to achieve full dispersion. Subsequently, the dispersion was quickly transferred to a quartz cuvette to record its fluorescence emission spectrum at an excitation wavelength of 390 nm.

[0059] An ideal fluorescent nanoprobe needs to accurately and specifically identify the target ions and minimize the interference of other coexisting pollutants. Figure 4As can be clearly seen in the figure, we carefully observed the fluorescence response of ATP-BDNOL-1 to a variety of common metal cations. When ATP-BDNOL-1 came into contact with metal ions other than Al(III) and Cu(II) (Cd(II), Co(II), Cr(III), Zn(II), K(I), Na(I), Mg(II), Mn(II), Ni(II), Pb(II)), its fluorescence intensity showed almost no significant change, exhibiting only extremely small fluctuations, indicating that these metal ions other than Al(III) and Cu(II) had little effect on the fluorescence of ATP-BDNOL-1. However, the situation was completely different for Al(III) and Cu(II). After adding Al(III) to the ATP-BDNOL-1 solution, the fluorescence intensity of the solution at 475nm showed a significant increase, and this upward trend was very stable and reproducible. However, when Cu(II) is introduced, the fluorescence emission peak intensity of ATP-BDNOL-1 at a wavelength of 475nm shows a significant quenching, which is in stark contrast to the fluorescence change caused by Al(III), fully demonstrating that ATP-BDNOL-1 has unique response characteristics to Al(III) and Cu(II). This characteristic indicates that this attapulgite nanofluorescent probe for dual ion detection has broad application prospects in the field of selective fluorescence detection of Al(III) and Cu(II) ions.

[0060] Example 8:

[0061] The present invention studies the adsorption capacity of ATP-BDNOL-1, a nano-fluorescent probe of attapulgite for dual ion detection obtained in Example 1, for Al(III) and Cu(II) under different pH conditions. A 100 mg / L aqueous solution of Al(III) and Cu(II) was prepared, the solution was transferred to a 100 mL conical flask, ATP-BDNOL-1 was added to the solution at a concentration of 1 mg / L, and the pH value of the solution was adjusted to different pH values. The suspension was kept at a constant temperature of 25°C and shaken at 120 rpm. After 12 hours, the attapulgite adsorbent was removed by centrifugation. The concentration of heavy metal ions in the solution was detected using inductively coupled plasma, the adsorption capacity was calculated, and the average value was taken after three repetitions.

[0062] like Figure 5 As shown in Figure 2, within the pH range of 2.0 to 6.0, the adsorption capacity of Al(III) and Cu(II) ions by ATP-BDNOL-1 generally increases with increasing pH. This may be because the H + The ion concentration is high, and the high concentration of H + Ions will occupy adsorption sites on the surface of the material. As the pH increases, H+ The decrease in ion concentration allows more adsorption sites to interact with Al(III) and Cu(II) ions, resulting in an increase in adsorption capacity. At pH 6.0, ATP-BDNOL-1 reached its maximum adsorption capacity for Al(III) and Cu(II) ions, with adsorption capacities of 17.7 mg / g for Al(III) and 38.9 mg / g for Cu(II). These results indicate that ATP-BDNOL-1 can be used as an adsorption material for Al(III) and Cu(II).

Claims

1. A attapulgite nanofluorescent probe for dual ion detection, characterized by: The fluorescent probe is loaded with quaternary ammonium salt ions and salicylic hydrazone fluorescent chromophores on the surface of the attapulgite material, and its general structural formula is as follows: in, It refers to attapulgite nanorod-shaped crystals, where n is an integer of 1 or 2, Q is a methyl group or an ethyl group, R is a hydrogen atom or a methyl group, and the R substitution position is one of the four substitution sites on the benzene ring.

2. A method for preparing a attapulgite nanofluorescent probe for dual ion detection, characterized in that: The preparation method comprises the following steps: Step 1. The attapulgite raw material ATP is first passed through a 200-mesh sieve to remove larger particles. After washing with deionized water, 0.15 mol / L HCl solution is added and mechanically stirred overnight. Then, it is washed with deionized water several times until neutral, dried and ground for use. The pretreated attapulgite is dispersed in an organic solvent, and a silane coupling agent containing a tertiary amino group is added. The reaction is heated at 60 to 80 ° C under nitrogen protection for 12 to 36 hours. After the reaction mixture is cooled, it is filtered, washed with ethanol three times, and dried in a vacuum oven at 60 ° C overnight to obtain attapulgite ATP-DATMS with a surface modified with a tertiary amino group. The reaction formula of the above synthesis steps is expressed as follows: Step 2: Add the ATP-DATMS prepared in step 1 to an organic solution containing 5-chloromethyl salicylaldehyde, disperse by ultrasonication, and stir at room temperature for 12 to 48 hours. After the reaction is complete, collect the product by centrifugation, wash it three times with ethanol, and finally dry it in a vacuum oven at 60°C overnight to obtain attapulgite ATP-CAS with salicylaldehyde grafted on its surface. The reaction formula of the above synthesis steps is expressed as follows: Step 3: Add the ATP-CAS and picolinyl hydrazide prepared in step 2 to an organic solvent, ultrasonically disperse, and react at 25-60° C. with stirring for 8-24 hours. After the reaction is completed, separate the product by centrifugation, wash it three times with ethanol, and finally dry it in a vacuum oven at 60° C. overnight to obtain attapulgite ATP-BDNOL modified with a salicylic hydrazone fluorescent chromophore. The above synthesis steps are expressed as follows:

3. The method for preparing a attapulgite nano-fluorescent probe for dual ion detection according to claim 2, wherein: The solid-liquid mass volume ratio of the attapulgite after sieving and removing impurities in step one to 0.15 mol / L hydrochloric acid solution is 1:30~60 g / mL; the organic solvent is one of dichloromethane, chloroform, isopropyl alcohol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the solid-liquid mass volume ratio of the activated attapulgite to the organic solvent is 1: 50-100 g / mL; the tertiary amino group-containing silane coupling agent is selected from any one of (N,N-dimethyl-3-aminopropyl)trimethoxysilane, (N,N-diethyl-3-aminopropyl)trimethoxysilane, (N,N-dimethyl-4-aminobutyl)trimethoxysilane, and (N,N-diethyl-4-aminobutyl)trimethoxysilane; the mass of the tertiary amino group-containing silane coupling agent is 0.5-2 times the mass of the activated attapulgite.

4. The method for preparing a attapulgite nano-fluorescent probe for dual ion detection according to claim 2, wherein: The organic solvent in step 2 is one of dichloromethane, chloroform, isopropanol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the solid-liquid mass volume ratio of the surface-modified tertiary amine-grouped attapulgite ATP-DATMS to the organic solvent is 1:50~80g / mL; the amount of the 5-chloromethyl salicylaldehyde and the mass ratio of the tertiary amine-modified attapulgite material ATP-DATMS is 1:0.5~2.

5. The method for preparing a attapulgite nano-fluorescent probe for dual ion detection according to claim 2, wherein: The organic solvent in step three is one of dichloromethane, chloroform, isopropanol, anisole, N,N-dimethylformamide, toluene, ethanol, acetone, methanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile or dioxane; the pyridine carboxylic acid hydrazide is selected from 2-pyridine carboxylic acid hydrazide, 3-methyl-2-pyridine carboxylic acid hydrazide, 4-methyl-2-pyridine carboxylic acid hydrazide, 5-methyl-2-pyridine carboxylic acid hydrazide or 6-methyl-2-pyridine carboxylic acid hydrazide; the solid-liquid mass volume ratio of the tertiary amine-modified attapulgite material ATP-DATMS to the organic solvent is 1:50~80g / mL; the mass ratio of the pyridine carboxylic acid hydrazide to the salicylaldehyde-modified attapulgite material ATP-CAS is 1:0.5~2.

6. The attapulgite nano-fluorescent probe for dual ion detection according to claim 1, characterized in that: The surface of the attapulgite nano fluorescent probe is modified with salicylic hydrazone groups as fluorescence response sites. When it binds to Al(III) in an aqueous medium, it exhibits a fluorescence enhancement effect, while when it binds to Cu(II), fluorescence quenching occurs. The probe exhibits high selectivity for multiple coexisting ions and can therefore be used for fluorescence detection of two metal ions, Al(III) and Cu(II), in water. At the same time, the material can simultaneously remove Al(III) and Cu(II) ions from water through adsorption.

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