CN107991336B - Method for rapidly and simultaneously detecting and separating Pb2+ and Cu2+ in water based on magnetic sensing - Google Patents

Abstract

The invention discloses a magnetic sensing-based method for rapidly and simultaneously detecting and separating Pb²⁺And Cu²⁺The method of (1), comprising: 1) preparation of Quercetin-coated magnetic Fe₃O₄Nanoparticles, 2) making △ T₂‑Pb²⁺And Cu²⁺A standard curve of concentration; 3) coating magnetic Fe with quercetin₃O₄Nanoparticles (QmNPs) bound to Pb²⁺And Cu²⁺Determination of △ T₂According to △ T₂‑Pb²⁺And Cu²⁺Calculating Pb from the standard curve of the concentration²⁺And Cu²⁺The concentration of (c); 4) under the action of magnetic field, utilizing magnetic adsorption method to adsorb and combine Pb²⁺And Cu²⁺The quercetin-coated magnetic Fe₃O₄Nanoparticles to effect Pb removal²⁺And Cu²⁺. The invention is based on QmNPs system and Pb²⁺Or Cu²⁺The coordination is carried out, aggregation and precipitation are generated under the action of an external magnetic field, and therefore, the Pb in the water can be simultaneously treated²⁺And Cu²⁺The method can be successfully applied to water and urine samples by detection and removal, has the advantages of high recovery rate, strong adsorption capacity, no potential secondary pollution and the like, and has good practicability.

Description

Magnetic sensing-based rapid simultaneous detection and separation of Pb in water2+And Cu2+Method (2)

Technical Field

The invention belongs to the technical field of magnetic nanoparticles and application thereof, and particularly relates to a magnetic sensing-based method for rapidly and simultaneously detecting and separating Pb in water²⁺And Cu²⁺The method of (1).

Background

Heavy metal ion contamination has important effects on the development of environment and organisms. Since excessive heavy metal ions pose serious threats to human health and the environment, it is important to develop a method for detecting and eliminating them. Thus, heavy metal ions (e.g., Pb) are introduced²⁺And Cu²⁺) Removal from sewage is of public concern. Among the heavy metal ions, Cu²⁺Plays a crucial role in environment, biological and chemical systems, etc., but the high concentration of Cu²⁺Damage to the liver and kidney can occur and the self-purging function can be seriously affected. Pb²⁺Is highly toxic heavy metal ion even at low concentrationCan pose a serious threat to human health and the environment. Thus, Pb is removed from contaminated water²⁺And Cu²⁺Is very necessary.

Different methods have been used to detect these heavy metal ions, such as fluorescence spectroscopy, atomic absorption spectroscopy and gas chromatography. However, these methods have many disadvantages, such as a small detection range, expensive equipment, complicated procedures, necessity of operation by a professional, etc., and obviously, the use requirements are not completely satisfied.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects in the prior art, the invention provides a magnetic sensing-based method for rapidly and simultaneously detecting and separating Pb²⁺And Cu²⁺Method for simultaneous detection and removal of Pb from contaminated water samples²⁺And Cu²⁺。

The technical scheme is as follows: in order to achieve the purpose of the invention, the invention adopts the technical scheme that:

magnetic sensing-based rapid simultaneous detection and separation method for Pb²⁺And Cu²⁺The method comprises the following steps:

1) preparation of Quercetin-coated magnetic Fe₃O₄A nanoparticle;

2) make △ T₂-Pb²⁺And Cu²⁺A standard curve of concentration;

3) coating magnetic Fe with quercetin₃O₄Nanoparticles (QmNPs) bound to Pb²⁺And Cu²⁺Determination of △ T₂According to △ T₂-Pb²⁺And Cu²⁺Calculating Pb from the standard curve of the concentration²⁺And Cu²⁺The concentration of (c);

4) under the action of magnetic field, utilizing magnetic adsorption method to adsorb and combine Pb²⁺And Cu²⁺The quercetin-coated magnetic Fe₃O₄Nanoparticles to effect Pb removal²⁺And Cu²⁺。

In the step 1), the specific process is as follows: adding FeCl into ultrapure water₃·6H₂O and FeCl₂·6H₂O, stirring and heating to 10 DEG0 ℃ until the solid is completely dissolved; then adding NH₃·H₂O, producing a black precipitate; magnetic Fe separation by centrifugal separation₃O₄Nano particles, and washing with water and ethanol; mixing Fe₃O₄Adding the powder into ultrapure water, and performing ultrasonic dispersion for 1 h; then adding quercetin to the suspension system, mixing with Fe₃O₄Reacting for 1h under the condition of ultrasonic dispersion; then, centrifugally separating out functionalized magnetic quercetin nanoparticles; and finally, washing with clear water for many times, and dispersing in deionized water for long-term storage.

In step 1), Fe₃O₄The mass ratio of the quercetin to the quercetin is 1: 1.

in step 2), △ T₂-Pb²⁺The standard curve of concentration is Y-52.41458X-8.88188, R²＝0.9912。

In step 2), △ T₂-Cu²⁺Concentration standard curve Y-49.69175X-0.06574, R²＝0.9983。

Pb²⁺Has a linear range of 4.8 × 10^-6mol L^-1～10^-4mol L^-1。

Cu²⁺Has a linear range of 5.0 × 10^-6mol L^-1～10^-4mol L^-1。

In the method, the adopted quercetin flavone is a natural product widely existing in plants, and belongs to a flavonoid compound with good biological activity. Research has shown that quercetin is an effective metal chelator with three possible chelation site competitions: 3-hydroxy-4-carbonylcatechol, 5-hydroxy-4-carbonylcatechol, 3 ', 4' -dihydroxycatechol. Experiments in this application confirm the metal ion Pb²⁺And Cu²⁺Coating with quercetin₃O₄Complexation of the system results in aggregation of the nanoparticles and changes in the spin relaxation time (T)₂) At T₂Change of (2) and T₂Based on the weighted brightness enhancement of the MR image, Pb can be detected²⁺And Cu²⁺The concentration of (c). In addition, the functional magnetic nanoparticles can also pass throughExternal magnetic field for removing Pb in polluted water²⁺And Cu²⁺And potential secondary pollution is avoided.

Has the advantages that: compared with the prior art, the method is based on a QmNPs system and Pb²⁺Or Cu²⁺Coordination is carried out, leading to the agglomeration of the QmNPs system, resulting in a relaxation time T₂Increase at △ T₂Standard curve of ion concentration, Pb²⁺R of (A) to (B)²＝0.9912，Cu²⁺R of (A) to (B)²0.9983, has good correlation, linear range of detection Pb²⁺At 4.8 × 10^-6mol L^-1～10^-4mol L^-1，Cu²⁺At 5.0 × 10^-6mol L^-1～10^-4mol L^-1. The QmNPs system reacts with Pb under the action of an external magnetic field^{2 +}Or Cu²⁺The coordination is carried out to generate aggregation and precipitation, thereby simultaneously treating Pb in water²⁺And Cu²⁺The method can be successfully applied to water and urine samples by detection and removal, has the advantages of high recovery rate, strong adsorption capacity, no potential secondary pollution and the like, and has good practicability.

Drawings

FIG. 1 shows quercetin coated Fe₃O₄A preparation route of nanoparticles;

FIG. 2 is a transmission electron microscope observation QMNPs topography; in the figure, a is Fe showing no modification₃O₄B is quercetin-coated Fe₃O₄C is the dispersion state of QmNPs, d is the addition of Pb²⁺The dispersion state of QmNPs;

FIG. 3 is Fe₃O₄(a) And infrared spectrograms of QMNPs (b);

FIG. 4 is Fe₃O₄(a) And XRD patterns of qmpns (b);

FIG. 5 is Fe₃O₄And T of QmNPs₂A relaxation time map;

FIG. 6 is 100mL Fe₃O₄Adding quercetin T into the water solution₂A relaxation time map;

FIG. 7 is a QMNPs system adding different metal ion pairs T₂Influence result graph of (2);

FIG. 8 is a schematic diagram of agglomeration;

FIG. 9 shows the addition of Cu by QmNPs system²⁺T of₂Changes and MRI change maps;

FIG. 10 shows the addition of Pb to QmNPs system²⁺T of₂Changes and MRI change maps;

FIG. 11 shows the following Pb in QmNPs system²⁺Or Cu²⁺Increased concentration of T₂A weighted MR map;

FIG. 12 is △ T in QMNPs system₂-Pb²⁺A standard curve of concentration;

FIG. 13 is △ T in QMNPs system₂-Cu²⁺A standard curve of concentration;

FIG. 14 is quercetin coated Fe₃O₄System to Cu²⁺、Pb²⁺The adsorption result chart of (1);

FIG. 15 is a graph showing the results of example 6.

Detailed Description

The present invention will be further described with reference to the following examples.

In the following examples, T₂(spin relaxation time) measured by 0.47T NMR (Niumag, Shanghai) Transmission Electron microscope (TEM, JEM-1400) for studying quercetin-coated magnetic Fe₃O₄Morphology and structure of nano core-shell particle nanoparticles (QMNPs). The system was studied using a Brooks D8Venture series single crystal X-ray diffractometer and Fourier transform infrared spectroscopy (FTIR) of Bruker VERTEX 80V series, and Perkin Elmer AA900T AAS for Pb²⁺And Cu²⁺The content of (b) was measured.

Example 1

The route diagram of the synthesis of the functionalized magnetic quercetin nanoparticles (QMNPs) is shown in figure 1, and the specific process is as follows: FeCl was added to 250mL of ultrapure water₃·6H₂O (10.85g) and FeCl₂·6H₂O (3.99g), stirred and heated to 100 ℃ until the solid was completely dissolved. Then adding NH₃·H₂O (5mL, 28%) produced a black precipitate. Magnetic Fe separation by centrifugal separation₃O₄Nanoparticles and washed three times with water and ethanol. Mixing 1mg of Fe₃O₄The powder was added to 100mL of ultrapure water and dispersed by sonication (40KHz, 30 ℃) for 1 h. Then adding a quantity of quercetin (10)^-5mol·L^-1) Adding into suspension system, and mixing with Fe₃O₄The reaction is carried out for 1h under the ultrasonic (40KHz, 30 ℃) dispersion condition. Subsequently, the functionalized magnetic quercetin nanoparticles (QMNPs) were isolated by centrifugation (15min, 15000 rmp). Finally, the product is rinsed several times with clear water and dispersed in deionized water for long-term storage.

The morphology of the QMNPs was observed by Transmission Electron Microscopy (TEM). FIG. 2a shows unmodified Fe₃O₄The particle size is between 20nm and 30 nm. FIG. 2b shows the morphology of QmNPs at Fe₃O₄The surface of the nanoparticles was successfully coated with quercetin. FIGS. 2c and d show the presence or absence of Pb in water samples from QmNPs, respectively²⁺The dispersed state of (a). As is clear from the figure, the addition of Pb is performed²⁺Thereafter, the magnetic sensor exhibits a phenomenon of agglomeration, aggregation and aggregation. This indirectly indicates that quercetin has been successfully embedded in Fe₃O₄Of (2) is provided.

Fe₃O₄(a) And Fourier transform Infrared Spectroscopy (FTIR) of QMNPs (b) as shown in FIG. 3. FIG. 3a, 567 cm^-1And 1632cm^-1The peaks at (A) are characteristic peaks of Fe-O bonds and FeOO bonds. 3500cm^-1The peak of (2) is a stretching vibration peak of O-H. In FIG. 3b, at 2900cm^-1And 1640cm^-1The peak at (b) is the stretching vibration of C ═ O. 1320-1210cm^-1The peak at (A) is a characteristic peak of the C-O bond of the carbonyl group. Therefore, from the above results, it was confirmed that the present example has successfully synthesized the magnetic QmNPs structure, and quercetin was coated in Fe₃O₄Is also effective on the surface of the nanoparticles.

FIG. 4 is Fe₃O₄And XRD patterns of QMPNs. The different diffraction peaks (a) on the curve can be considered as Fe₃O₄Face centered cubic phase (JCPDS card 65-3107). The diffraction pattern of QMNPs (b) after coating with quercetin was clearly different from that of Fe₃O₄(a) Crystallization ofThe change in degree may be caused by the quercetin layer.

Example 2

To compare two samples QmNPs and Fe₃O₄The state of the nano particles in water is respectively measured, and T of two samples is measured₂: the sample solution was placed in a 5 mm glass tube, T₂Measured by a 0.55T nmr (TE 1000s, TR 1500 ms). T is₂The measurement interval of (2) was 5 minutes, and each sample was scanned 3 times.

The results are shown in FIG. 5, Fe₃O₄T of₂A significant increase in 22 minutes indicated Fe under magnetic field conditions₃O₄The nanoparticles are aggregated in clusters in water. Although only minor changes occurred in QMNPs, this suggests that quercetin-coated Fe₃O₄Can be dispersed in water. In the quercetin structure, 5 hydroxyl groups can be reacted with Fe₃O₄Form hydrogen bonds to Fe₃O₄The nanoparticles are better dispersed in water. However, the content of quercetin affects the stability of QMNPs. At 100mL Fe₃O₄The change in T2 relaxation time was tested for 4 different QMNPs systems by adding 4 different qualities of quercetin (0.5mg,1.0mg, 1.5mg,2.0mg) to the aqueous solution. The results are shown in FIG. 6, which shows that T of QmNPs increases with the content of quercetin₂Decrease before increase, which indicates that the QMNPs system is at 100mL Fe₃O₄The stability is best when 1.0mg quercetin is contained in the aqueous solution. In Fe₃O₄Adding small amount of quercetin, quercetin and Fe into the water solution₃O₄Hydrogen bonds are formed between the QMNPs, and the stability of the QMNPs system is improved. When the content of quercetin increases to a certain extent, it is coated with Fe₃O₄The hydrogen bonding interactions of quercetin on the surface of the nanoparticles are increased, resulting in a state of aggregation tending towards the QMNPs system. Therefore, the quercetin content is important in preparing QMNPs.

Example 3 identification of Metal ions by QMNPs

To detect T of different metal ions by QmNPs system₂1mL of QMNPs solution with 10. mu.L of different metal ions (Co)²⁺，K⁺，Zn²⁺，Na⁺，Ni²⁺，Cd²⁺，Li⁺，Fe³⁺，Fe²⁺，Mn²⁺， Mg²⁺，La²⁺，Cu²⁺，Pb²⁺) Acetic acid/nitrate salt standard solution (1 × 10)^-3mol·L^-1) Mixing, then placing the sample solution into a 5 mm glass tube, T₂Measured by a 0.55T nmr (TE 1000s, TR 1500 ms).

Adding each metal ion into the prepared detection system respectively, and recording T₂The relaxation time. The results are shown in FIG. 7, which shows only Pb²⁺And Cu²⁺Let T₂The relaxation time changes significantly.

When it is Pb²+ or Cu²⁺When added to QMNPs solution, QMNPs are mixed with Pb²⁺Or Cu²⁺Coordination reactions occur between them, resulting in the dispersion of QMNPs into clusters, as shown in scheme 8. The larger nanoparticles alter the magnetic relaxation properties of the surrounding water protons, thereby increasing T₂Relaxation time, as shown in FIGS. 9 and 10, this phenomenon can be measured by T of MRI₂The intensity change of the weighted Magnetic Relaxation (MR) shows that, at the same time, the QMNPs system precipitates under the influence of an external magnetic field.

Example 4QMNPs System for Pb²⁺And Cu²⁺Detection of (2)

To measure different concentrations of Pb²⁺And Cu²⁺For T₂The test solution was a solution with 1mL as the detector and different concentrations of Pb²⁺And Cu²⁺Mixing standard solutions, injecting into test tube, and measuring T₂。T₂After measurement, T can be obtained₂The weighted image of (1).

The system can detect Pb with different concentrations²⁺Or Cu²⁺. It can be observed from FIG. 11 that as Pb in the sample proceeds²⁺And Cu²⁺The MR image of the sample will also gradually brighten with increasing concentration, T₂The relaxation time increases accordingly.

1mL of magnetic sensor was added to the glass tube for testing and its T recorded by low field NMR₂A value; will not respectively failAdding lead salt solution and copper salt solution with the same concentration dropwise, and recording their T with low-field nuclear magnetic resonance apparatus₂Value, T to be measured before and after₂The values are subtracted to obtain △ T₂And drawing △ T₂With different concentrations of Pb²⁺And Cu²⁺△ T₂-Pb²⁺The standard curve of concentration is shown in FIG. 12, wherein Y is 52.41458X-8.88188, R²＝0.9912。△T₂-Cu²⁺The standard curve of concentration is shown in FIG. 13, wherein Y is 49.69175X-0.06574, R²0.9983, which have good correlation, the linear range of detection Pb²⁺At 4.8 × 10^-6mol L^-1～10^-4mol L^-1，Cu²⁺At 5.0 × 10^-6mol L^-1～10^-4mol L^-1. In which Pb is²⁺Detection limit of 1.6 × 10^-6mol L^-1，Cu²⁺Detection limit of 2 × 10^-6mol L^-1。

Example 5 application of the QMNPs System in Water and urine samples

Adding 1mmol/L Pb²⁺Or Cu²⁺Added to 3.0mL of water, followed by QmNPs. Precipitation occurs when the mixture is acted upon by a magnetic field, as shown in FIG. 14. Half an hour later, the suspension is carefully removed and the Pb is determined²⁺Or Cu²⁺The concentration of (c). The adsorption formula of each gram of the system is that M ═ C₀-C)×V]×m^-1，C₀And C is solution Pb²⁺Or Cu²⁺Initial and final concentrations of (mg. L)^-1) V is the sample volume (L) and m is the weight (g) of QmNPs. Calculated for Pb²⁺And Cu²⁺The maximum adsorption amounts were 68mg and 71mg, respectively, which are superior to the prior art methods (shown in Table 1). Therefore, the magnetic adsorption method of QmNPs is used for removing Pb in the aqueous solution²⁺And Cu²⁺And (4) the method is feasible.

Table 1 for Cu²⁺、Pb²⁺Adsorption amount of (2)

Note: specific references are as follows:

1、Y.Chen,R.C.Haddon,S.Fang,A.M.Rao,P.C.Eklund,Chemical attachment oforganic functional groups to single-walled carbon nanotube material,J.Mater.Res.13 (1998)2423–2431.

2、N.Chiron,R.Guilet,E.Deydier,Adsorption of Cu(II)and Pb(II)onto agrafted silica:isotherms and kinetic models,Water Res.37(2003)3079–3086.

3、L.Curkovic,S.Cerjan-Stefanovic,A.RastoveanMioe,Batch Pb²⁺and Cu²⁺removal by electric furnace slag,Water Res.35(2001)3436–3440.

4、C.Zhang,J.Sui,J.Li,Y.Tang,W.Cai,Efficient removal of heavy metalions by thiol-functionalized superparamagneticcarbon nanotubes,Chem.Eng.J.210(2012)45–52.

5、S.

A.Veronovski,Z.Novak,Z.Knez,Silica aerogels modifiedwith mercapto functional groups used for Cu(II)and Hg(II)removal from aqueoussolutions, Desalination 269(2011)223-230.

this example also designed to evaluate the QMPNs system for Pb in water and urine samples (after acid digestion)²⁺And Cu²⁺Performance of detection and removal capability. First, 10. mu.L of a solution containing Pb²⁺And Cu²⁺The water or urine sample of (2) was added to a solution of 1mL QMNPs system. Low field NMR for Pb detection²⁺And Cu²⁺And Pb was measured by the AAs method²⁺And Cu²⁺The concentration of (c). Results are shown in tables 2 and 3, and the measured results are substantially the same as those of the AAs method, thus proving that QmNPs can be used as a magnetic sensor for Pb²⁺And Cu²⁺Qualitative and quantitative analyses were performed.

TABLE 2QMNPs system for Pb²⁺Detection and removal capability of

In addition, 60 μ g QMNNPs was added to water or urineNeutralize Pb²⁺Or Cu²⁺Coordinating, adsorbing metal ions under external magnetic field condition, filtering the mixed solution after 30min, and measuring Pb in the filtrate by atomic absorption spectrometry²⁺Or Cu²⁺The concentration of (c). The results (tables 2 and 3) show that: 90.24-92.00% of Pb in water sample²⁺And 88.2 to 91.9% of Cu²⁺90.90-92.00% Pb in urine sample²⁺And 91.8 to 91.9% of Cu²⁺Adsorbed and removed by the QmNPs system.

TABLE 3QMNPs system for Cu²⁺Detection and removal capability of

Example 6

Kaempferol modified magnetic Fe₃O₄The method for preparing nanoparticle system is the same as example 1, wherein kaempferol is used to replace quercetin, and the prepared product is used to detect and remove different ions in water, the method is the same as example 3, and the result is shown in FIG. 15, which shows that the selectivity of the prepared product to different ions is poor, and the simultaneous detection and removal of Pb cannot be satisfied²⁺And Cu²⁺The use requirements of (2).

Claims (4)

1. Magnetic sensing-based rapid simultaneous detection and separation method for Pb²⁺And Cu²⁺The method is characterized by comprising the following steps:

1) preparation of Quercetin-coated magnetic Fe₃O₄A nanoparticle; the specific process is as follows: adding FeCl into ultrapure water₃·6H₂O and FeCl₂·6H₂O, stirring and heating to 100 ℃ until the solid is completely dissolved; then adding NH₃·H₂O, producing a black precipitate; magnetic Fe separation by centrifugal separation₃O₄Nano particles, and washing with water and ethanol; mixing Fe₃O₄Adding the powder into ultrapure water for ultrafiltrationSound dispersion is carried out for 1 h; then adding quercetin to the suspension system, mixing with Fe₃O₄Reacting for 1h under the condition of ultrasonic dispersion; then, centrifugally separating out functionalized magnetic quercetin nanoparticles; finally, washing the magnetic quercetin nanoparticles for multiple times by using clear water, and dispersing the magnetic quercetin nanoparticles in deionized water for long-term storage;

2) make △ T₂-Pb²⁺And Cu²⁺Standard curve of concentration △ T₂-Pb²⁺The standard curve of concentration is Y = 52.41458X-8.88188, R²=0.9912；△T₂-Cu²⁺The standard curve of concentration is Y = 49.69175X-0.06574, R²=0.9983, wherein, △ T₂-difference between adjacent relaxation times, Y being △ T₂X is the ion concentration, 10^-5mol·L^-1；

3) Coating magnetic Fe with quercetin₃O₄Nanoparticle bound Pb²⁺And Cu²⁺△ T was determined₂According to △ T₂- Pb²⁺And Cu²⁺Calculating Pb from the standard curve of the concentration²⁺And Cu²⁺The concentration of (c);

4) under the action of magnetic field, utilizing magnetic adsorption method to adsorb and combine Pb²⁺And Cu²⁺The quercetin-coated magnetic Fe₃O₄Nanoparticles to effect Pb removal²⁺And Cu²⁺。

2. Magnetic sensing based rapid simultaneous detection and separation of Pb according to claim 1²⁺And Cu²⁺Characterized in that, in step 1), Fe₃O₄The mass ratio of the quercetin to the quercetin is 1: 1.

3. magnetic sensing based rapid simultaneous detection and separation of Pb according to claim 1²⁺And Cu²⁺Characterized by the fact that Pb is²⁺Has a linear range of 4.8 × 10^-6mol L^-1~10^-4mol L^-1。

4. According to the rightMagnetic sensing based rapid simultaneous detection and separation of Pb according to claim 1²⁺And Cu²⁺Characterized in that Cu^{2 +}Has a linear range of 5.0 × 10^-6mol L^-1~10^-4mol L^-1。

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