CN115820248B - Method for preparing carbon quantum dots and detecting palladium ions by utilizing landfill leachate membrane concentrate - Google Patents
Method for preparing carbon quantum dots and detecting palladium ions by utilizing landfill leachate membrane concentrate Download PDFInfo
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- CN115820248B CN115820248B CN202211072952.5A CN202211072952A CN115820248B CN 115820248 B CN115820248 B CN 115820248B CN 202211072952 A CN202211072952 A CN 202211072952A CN 115820248 B CN115820248 B CN 115820248B
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a preparation method of novel carbon quantum dots, which is characterized in that landfill leachate membrane concentrate is used as a carbon source and synthesized by a passivating agent assisted hydrothermal method; the prepared carbon quantum dot solution is subjected to filtration and dialysis and then is subjected to freeze drying, so that dry solid carbon quantum dots are obtained; placing carbon quantum dots as fluorescent probes on a fluorescent probe containing Pd 2+ Fluorescence quenching occurs to specifically detect Pd in water 2+ . The preparation method of the carbon quantum dot prepared by the invention is simple, is easy to operate, and can be used for Pd in water 2+ The detection method has high sensitivity and good selectivity, and has wide application prospect in the field of environmental detection.
Description
Technical Field
The invention relates to the field of nano materials, in particular to a method for preparing carbon quantum dots from a landfill leachate membrane concentrate and applying the carbon quantum dots to palladium ion detection.
Background
Carbon Quantum Dots (CQDs) are a kind of carbon nanoparticles having a size of less than 10nm in a sphere-like shape and having fluorescent properties. As a novel zero-dimensional nanomaterial, the carbon quantum dot not only inherits the advantages of fluorescent micromolecules, such as adjustable luminescence color, high chemical stability, easy preparation, low cost and good water solubility, but also has the advantages of photobleaching resistance, high light stability, no light flicker, wide excitation wavelength range, no toxicity, environmental protection, easy functionalization, good biocompatibility and the like, and is a good fluorescent probe.
In the prior art, the preparation method of the carbon quantum dots mostly adopts pure substances such as glucose, citric acid and the like as carbon sources for synthesis, so that the problems of high cost, complex preparation and treatment processes of samples and the like exist, and the research on the method for preparing the carbon quantum dots by adopting refractory pollutants as raw materials in a green environment-friendly way is less.
The treatment of household garbage can generate a large amount of garbage percolate, and after the treatment of the household garbage by a film process, a large amount of film concentrate is generated, and the main components of the household garbage are biochemical humic acid, inorganic salt and ammonia nitrogen, so that the treatment of the household garbage can cause great difficulty for subsequent further treatment, but the household garbage is also an ideal carbon source for preparing carbon quantum dots.
Palladium metal has high temperature resistance, corrosion resistance and strong extensibility inHas wide application in the fields of industry and the like. However, it contains Pd 2+ The industrial waste of (2) is discharged into the environment, generates water and soil, and accumulates and amplifies pollution through biological chains, thus creating serious threat to human health. Pd (Pd) 2+ Can cause a series of cytotoxicity effects and can be extremely harmful to human bodies. Thus, pd in a development environment 2+ The rapid, low-cost and green detection technology has great significance for reducing the risk of heavy metal pollution.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a method for preparing carbon quantum dots by taking garbage leachate membrane concentrate as a carbon source and adopting a passivating agent-assisted hydrothermal method, and the prepared carbon quantum dot fluorescent probe can realize Pd in water 2+ Is selected from the group consisting of a plurality of detection probes.
In order to achieve the above purpose, the present invention is realized by the following technical scheme:
a method for preparing concentrated solution of landfill leachate membrane and applicable to Pd 2+ The detected carbon quantum dots are prepared by the following steps:
and step 1, measuring 10-20mL of landfill leachate membrane concentrate in a polytetrafluoroethylene lining, then adding 0.5-2g of passivating agent into the polytetrafluoroethylene lining to assist a hydrothermal method to synthesize carbon quantum dots, and performing ultrasonic treatment for 5-15min to obtain a uniformly dispersed solution.
And 2, placing the solution into a 100mL reaction kettle, heating the solution for 1 to 9 hours at the temperature of 100 to 300 ℃ by using a muffle furnace, and taking out the solution after the reaction kettle is naturally cooled.
And 3, passing the cooled solution through a microporous water system filter membrane to remove macromolecular impurities, and then placing the solution into a dialysis bag to purify and dialyze in deionized water for 20-30 hours to remove micromolecular and salt impurities.
And 4, transferring the solution in the dialysis bag into a round-bottom flask, concentrating for 1-3h by adopting a rotary evaporator to obtain a carbon quantum dot solution prepared by taking a landfill leachate membrane concentrate as a raw material, and freeze-drying the solution for 1-2d to obtain brown carbon quantum dot powder.
Further, the passivating agent in the step 1 is any one of polyethylene glycol, ethylenediamine tetraacetic acid, acrylamide and allyl alcohol, and the molecular weight is any one of 1000-5000 types.
Further, the molecular weight cut-off of the dialysis bag in the step 3 is 1000-3000.
Further, the pore size of the microporous water-based filter membrane in the step 3 is 0.1-0.5 μm.
Further, the rotating speed of the rotary evaporator in the step 4 is 40-60r/min, and the heating temperature is 50-70 ℃.
The invention also provides a method for detecting Pd by using the carbon quantum dots 2+ The method is characterized by comprising the following steps:
(1) Preparing buffers with different pH values, adding the buffers with different pH values into the carbon quantum dot powder with the same mass, and detecting the fluorescence intensity to obtain the optimal pH of the carbon quantum dot.
(2) Taking 0.1-0.5g of carbon quantum dot powder, adding 10-30mL of pH buffer solution, and carrying out ultrasonic treatment for 5-15min to obtain fluorescent probe solution.
(3) Pd with different concentrations are respectively added into the fluorescent probe solution 2+ Standard solution and detection with fluorescence spectrophotometer because Pd 2+ Can obviously change or even quench the fluorescence of the carbon quantum dots, so that whether the solution contains Pd or not can be judged according to the obtained fluorescence spectrogram 2+ 。
(4) The optimal excitation wavelength (300-400 nm) is selected to measure the addition of Pd with different concentrations 2+ The fluorescence intensity of the fluorescent probe solution of the standard solution was plotted as a linear regression equation based on the fluorescence quenching ratio.
Preferably, the pH buffer solution is any one of BR buffer solution, phosphate buffer solution, acetic acid-sodium acetate buffer solution and borax buffer solution.
Preferably, the optimal pH value detected by the carbon quantum dots is between 5 and 7.
Preferably, pd is added 2+ The concentration of the standard solution is 0-200 mu mol/L.
Preferably Pd 2+ The detection limit of the concentration is 0.5-2 mu mol/L.
Preferably, the optimal excitation wavelength range is 330-360nm
Preferably, the linear regression equation is y=0.0122+0.18, where x is Pd 2+ Concentration in. Mu. Mol/L, linear interval is 10-40. Mu. Mol/L, and fitting degree of the linear fitting is 0.9945.
The invention has the advantages and beneficial effects that:
(1) The invention takes the high-concentration organic pollutant landfill leachate membrane concentrate as the raw material, and prepares the high-concentration organic pollutant landfill leachate membrane concentrate which can be used for detecting Pd by using a passivating agent-assisted hydrothermal method 2+ The fluorescent carbon quantum dots realize the resource utilization of the membrane concentrate in the municipal waste treatment process, and the prepared fluorescent carbon quantum dots have good fluorescent property and can be used for heavy metal Pd 2+ And (3) detecting fluorescent carbon quantum dots.
(2) The fluorescent probe prepared by the invention is successfully applied to Pd in water 2+ Has extremely high sensitivity, selectivity and anti-interference performance in the detection.
(3) The preparation method is simple and convenient to operate, is environment-friendly, and the prepared carbon quantum dots are nontoxic, convenient to recycle and free of environmental pollution risks.
Drawings
Fig. 1 is a transmission electron microscope image of a carbon quantum dot prepared by the method.
Fig. 2 is a structural and surface morphology characterization of the carbon quantum dots prepared according to the present invention. a) An infrared spectrum; b) XRD spectrum; c) XPS spectrum; d) C1 s high resolution XPS spectrum.
FIG. 3 is a graph showing fluorescence spectra of carbon quantum dots according to the present invention under different test conditions. a) Different excitation wavelengths; b) Different pH conditions.
FIG. 4 is a graph showing the comparison of fluorescence intensity of quenching caused by detection of different heavy metals by using the carbon quantum dots in the invention. a) Different heavy metal ions; b) The interfering ions are present at a concentration of 10 times.
FIG. 5 shows the fluorescence spectrum change of the carbon quantum dots prepared by the invention after palladium ions with different concentrations are added. a) A fluorescence spectrum; b) Fluorescence intensity changes; c) Concentration linear fit interval.
Detailed Description
The following examples will provide those skilled in the art with a more complete understanding of the invention, but are not intended to limit the invention in any way.
Example 1:
a method for preparing concentrated solution of landfill leachate membrane and applicable to Pd 2+ The detected carbon quantum dots are prepared by the following steps:
and step 1, measuring 10mL of landfill leachate membrane concentrate in a polytetrafluoroethylene lining, adding 0.5g of passivating agent into the polytetrafluoroethylene lining to assist a hydrothermal method to synthesize carbon quantum dots, and performing ultrasonic treatment for 5min to obtain a uniformly dispersed solution.
And 2, placing the solution into a 100mL reaction kettle, heating the solution for 3 hours at the temperature of 100 ℃ by using a muffle furnace, and taking out the solution after the reaction kettle is naturally cooled.
And 3, passing the cooled solution through a microporous water system filter membrane to remove macromolecular impurities, and then placing the solution into a dialysis bag to purify and dialyze in deionized water for 24 hours to remove micromolecular and salt impurities.
And 4, transferring the solution in the dialysis bag into a round-bottom flask, concentrating for 1h by adopting a rotary evaporator, wherein the rotating speed of the rotary evaporator is 40r/min, the heating temperature is 50 ℃, obtaining carbon quantum dot solution prepared by taking landfill leachate film concentrate as a raw material, and then freeze-drying the solution for 24h to obtain brown carbon quantum dot solid powder.
Fig. 1 is a transmission electron microscope image of the prepared carbon quantum dots, and it can be seen that the synthesized carbon quantum dots have a particle size of about 4-6nm and a lattice spacing of 0.309nm.
Example 2:
a method for preparing concentrated solution of landfill leachate membrane and applicable to Pd 2+ The detected carbon quantum dots are prepared by the following steps:
and step 1, measuring 15mL of landfill leachate membrane concentrate in a polytetrafluoroethylene lining, adding 1.0g of passivating agent into the polytetrafluoroethylene lining to assist a hydrothermal method to synthesize carbon quantum dots, and performing ultrasonic treatment for 10min to obtain a uniformly dispersed solution.
And 2, placing the solution into a 100mL reaction kettle, heating the solution for 5 hours at the temperature of 150 ℃ by using a muffle furnace, and taking out the solution after the reaction kettle is naturally cooled.
And 3, passing the cooled solution through a microporous water system filter membrane to remove macromolecular impurities, and then placing the solution into a dialysis bag to purify and dialyze in deionized water for 48 hours to remove micromolecular and salt impurities.
And 4, transferring the solution in the dialysis bag into a round-bottom flask, concentrating for 1h by adopting a rotary evaporator, wherein the rotating speed of the rotary evaporator is 50r/min, the heating temperature is 60 ℃, obtaining carbon quantum dot solution prepared by taking landfill leachate film concentrate as a raw material, and then freeze-drying the solution for 36h to obtain brown carbon quantum dot solid powder.
Fig. 2 shows characterization results of the infrared spectrum, the XPS spectrum and the XRD spectrum of the prepared carbon quantum dots, and shows that the prepared carbon quantum dots have basic carbon quantum dot structures, and the surfaces of the synthesized carbon quantum dots have a large number of oxygen-containing functional groups and have certain graphitized structures.
Example 3:
a method for preparing concentrated solution of landfill leachate membrane and applicable to Pd 2+ The detected carbon quantum dots are prepared by the following steps:
and step 1, measuring 20mL of landfill leachate membrane concentrate in a polytetrafluoroethylene lining, adding 2.0g of passivating agent into the polytetrafluoroethylene lining to assist a hydrothermal method to synthesize carbon quantum dots, and performing ultrasonic treatment for 15min to obtain a uniformly dispersed solution.
And 2, placing the solution into a 100mL reaction kettle, heating the solution for 7 hours at the temperature of 200 ℃ by using a muffle furnace, and taking out the solution after the reaction kettle is naturally cooled.
And 3, passing the cooled solution through a microporous water system filter membrane to remove macromolecular impurities, and then placing the solution into a dialysis bag to purify and dialyze in deionized water for 36 hours to remove micromolecular and salt impurities.
And 4, transferring the solution in the dialysis bag into a round-bottom flask, concentrating for 5 hours by adopting a rotary evaporator, wherein the rotating speed of the rotary evaporator is 70r/min, the heating temperature is 70 ℃, the carbon quantum dot solution prepared by taking the landfill leachate film concentrated solution as a raw material is obtained, and then the solution is freeze-dried for 48 hours, so that brown carbon quantum dot solid powder is obtained.
Fig. 3 (a) shows the corresponding emission wavelength and fluorescence intensity of the carbon quantum dot under different excitation wavelengths, and it can be seen from the graph that the fluorescence intensity is maximum when excited at 340nm, which proves that the carbon quantum dot has good optical performance. Fig. 3 (b) tests the stability of carbon quantum dots with different pH, and when the pH of the solution increases from 2 to 6, the fluorescence intensity of the carbon quantum dots increases, and as the pH increases above 7.0, the fluorescence intensity of the carbon quantum dots starts to decrease gradually, and when the pH is 6, the optimal pH for preparing such carbon quantum dots is obtained. The strong reaction of carbon quantum dots to pH changes is believed to originate from the protonation of their surface amino and carboxyl groups. Since the pH change may cause the protonation or deprotonation of the central fluorescent emission point of the carbon quantum dot, the fluorescence intensity of the carbon quantum dot may be significantly reduced under acidic and alkaline conditions.
Example 4:
(1) Taking 0.1g of the carbon quantum dot solid powder prepared in the embodiment 1-3, adding 10mL of the buffer solution with the optimal pH value obtained by measurement, and shaking uniformly to obtain a fluorescent probe solution.
(2) Heavy metal cations and 10 times of interferents thereof with different types and the same concentration (20 mu mol/L) are added into the fluorescent probe solution, and the fluorescence intensity is measured by using a fluorescence spectrophotometer.
(3) And (3) counting the fluorescence intensity of each solution in the step (2), and drawing a corresponding fitting curve.
As shown in FIG. 4, it can be seen that Pd 2+ The addition of (3) leads to a significant decrease in the fluorescence intensity of the solution. In contrast, the addition of other cations only slightly decreased or hardly changed the fluorescence intensity, and the fluorescence intensity was not substantially changed at 10-fold concentration. This indicates that the prepared carbon quantum dots are opposite to Pd 2+ Has good selectivity.
Example 5:
pd is detected by fluorescent probe prepared from the carbon quantum dots 2+ Comprises the following steps
(1) 0.1g of the carbon quantum dot solid powder prepared in the examples 1-3 was taken and 10mL of pH buffer solution with pH of 6 was added to obtain a fluorescent probe solution.
(2) Adding to the fluorescent probe solutionPd at 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200. Mu. Mol/L 2+ And its fluorescence intensity was detected by a spectrophotometer.
(3) And (3) counting the fluorescence intensity of each solution in the step (2), and drawing a corresponding fitting curve.
As shown in FIG. 5, with Pd 2+ The concentration is increased, and the fluorescence intensity of the carbon quantum dot solution is gradually reduced. A linear interval was found in the range of 10-40. Mu. Mol/L. As can be seen from the figure, in Pd 2+ Under the condition of higher concentration, the optimal emission wavelength of the fluorescent carbon quantum dot has obvious red shift, which shows that the synthesized carbon quantum dot has wider fluorescence emission peak, and the other side of the synthesized carbon quantum dot can also be mixed with Pd 2+ Is related to the change of the binding sites on the surface of the carbon quantum dots. Further performing linear fitting on the found linear interval, wherein the fluorescence quenching rate is taken as an ordinate, pd 2+ The concentration is on the abscissa, and the fitting result is shown in the graph. As can be seen from the graph, in the range of 10-40. Mu. Mol/L, the linear equation is y=0.0122+0.18 (R 2 =0.9945), the limit of detection is. It can be seen that the fluorescence intensity of the carbon quantum dots and Pd in the linear interval 2+ The method has good linear relation and can be used for further detection of actual water samples.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (8)
1. A method for preparing carbon quantum dots by utilizing a landfill leachate membrane concentrate, which is characterized by comprising the following steps:
step 1, measuring 10-20mL of landfill leachate membrane concentrate in a polytetrafluoroethylene lining, then adding 0.5-2g of passivating agent into the polytetrafluoroethylene lining to assist a hydrothermal method to synthesize carbon quantum dots, and performing ultrasonic treatment for 5-15min to obtain a uniform dispersion solution;
step 2, placing the solution into a 100mL reaction kettle, heating the solution for 1 to 9 hours at the temperature of 100 to 300 ℃ by using a muffle furnace, and taking out the solution after the reaction kettle is naturally cooled;
step 3, passing the cooled solution through a microporous water system filter membrane to remove macromolecular impurities, and then placing the solution into a dialysis bag to purify and dialyze in deionized water for 20-30 hours to remove micromolecular and salt impurities;
and 4, transferring the solution in the dialysis bag into a round bottom flask, concentrating for 1-3h by adopting a rotary evaporator to obtain a carbon quantum dot solution prepared by taking a landfill leachate membrane concentrate as a raw material, and freeze-drying the solution for 1-2 days to obtain brown carbon quantum dot powder.
2. The method for preparing carbon quantum dots according to claim 1, wherein the passivating agent is any one of polyethylene glycol, ethylenediamine tetraacetic acid, acrylamide and propenol, and the molecular weight is any one of 1000-5000 types.
3. The method of preparing carbon quantum dots of claim 1, wherein the dialysis bag has a molecular weight cut-off of 1000-3000.
4. The method for producing carbon quantum dots according to claim 1, wherein the pore size of the microporous aqueous filter membrane is 0.1 to 0.5 μm.
5. The method for preparing carbon quantum dots according to claim 1, wherein the rotational speed of the rotary evaporator is 40-60r/min and the heating temperature is 50-70 ℃.
6. Pd detection by using carbon quantum dots prepared by the method of any one of claims 1-5 2+ The method is characterized by comprising the following steps:
step 1, preparing buffers with different pH values, adding the buffers with different pH values into carbon quantum dot powder with the same mass, and detecting the fluorescence intensity to obtain the optimal pH value of the carbon quantum dot;
step 2, taking 0.1-0.5g of carbon quantum dot powder, adding 10-30mL of pH buffer solution, and carrying out ultrasonic treatment for 5-15min to obtain fluorescent probe solution;
step 3, adding 10-40 mu mol/L Pd into the fluorescent probe solution respectively 2+ The standard solution was then detected by a fluorescence spectrophotometer.
7. The method according to claim 6, wherein the pH buffer is any one of BR buffer, phosphate buffer, acetic acid-sodium acetate buffer, borax buffer.
8. The method of claim 6, wherein the carbon quantum dots have an optimal pH of between 5 and 7.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211072952.5A CN115820248B (en) | 2022-09-02 | 2022-09-02 | Method for preparing carbon quantum dots and detecting palladium ions by utilizing landfill leachate membrane concentrate |
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| CN202211072952.5A CN115820248B (en) | 2022-09-02 | 2022-09-02 | Method for preparing carbon quantum dots and detecting palladium ions by utilizing landfill leachate membrane concentrate |
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| Publication Number | Publication Date |
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