Cadmium sulfide light quantum dot, preparation method and application thereof, and method for detecting iron content

Abstract

The invention provides a cadmium sulfide light quantum dot, a preparation method and application thereof, and a method for detecting iron content. The preparation method of the cadmium sulfide light quantum dot comprises the following steps: (1) mixing strong base, a compound containing carbon-sulfur double bonds and alcohol amine I to obtain a sulfur-containing ligand; mixing alginate and water-soluble cadmium salt II, so as to obtain an alginate-cadmium ion chelate; (2) mixing a sulfur-containing ligand with the alginate-cadmium ion chelate compound to obtain a mixture III; the cadmium sulfide light quantum dot can generate a fluorescence quenching effect on iron ions, can detect the content of trace iron in glass, is stable in detection and small in error, and is suitable for industrial production and application.

Description

Technical Field

[0001] The present disclosure relates to the field of nano fluorescent materials, and in particular to a cadmium sulfide light quantum dot and a preparation method and application thereof, and a method for detecting iron content. Background Art

[0002] The transmittance of photovoltaic glass directly affects the photoelectric conversion efficiency. According to research by relevant institutions, every 1% increase in photoelectric conversion efficiency can reduce costs by 7%. In the production of photovoltaic glass, the transmittance of the glass is often further improved by controlling the content of colored impurity elements in the glass. Iron is a common colored impurity element in photovoltaic glass. It is generally introduced from raw materials and can also be introduced by crushing equipment during the crushing process of the glass. As the total iron content in the batch increases, the average transmittance of the glass in the wavelength range of 400-1200nm decreases linearly. Specifically, for every 100ppm increase in impurity iron content, the average transmittance of the glass decreases by about 0.5%. The iron content in subway ultra-white photovoltaic glass is generally controlled below 150ppm, or even below 100ppm.

[0003] At present, ICP or ICP-MS is generally used to detect trace iron content below 100 ppm. This method is effective for detecting iron content around 100 ppm, but for lower iron content, such as below 50 ppm, the detection effect is poor, the detection data fluctuates greatly, and the data error is unacceptable.

[0004] Therefore, it is urgent to provide a new detection method for the detection of ultra-low impurity iron content to meet the needs of photovoltaic glass production. Summary of the invention

[0006] A technical problem to be solved by the present disclosure is that the existing technology has poor effect and large error in detecting the iron content below 100 ppm in photovoltaic glass.

[0007] In order to solve the above technical problems, the present disclosure provides a method for preparing cadmium sulfide light quantum dots, which comprises the following steps:

[0008] (1) mixing a strong base, a carbon-sulfur double bond-containing compound and an alcohol amine to obtain a sulfur-containing ligand; mixing alginate and a water-soluble cadmium salt to obtain an alginate-cadmium ion chelate;

[0009] (2) Mixing the sulfur-containing ligand and alginate-cadmium ion chelate III.

[0010] In some embodiments, in step (1), the strong base is sodium hydroxide and / or potassium hydroxide; in some specific embodiments, the strong base is sodium hydroxide.

[0011] In some embodiments, the carbon-sulfur double bond-containing compound is selected from at least one of carbon disulfide, thiourea and thioacetamide; in some specific embodiments, the carbon-sulfur double bond-containing compound is carbon disulfide.

[0012] In some embodiments, the alcoholamine is selected from at least one of triethanolamine, diethanolamine and ethanolamine; in some specific embodiments, the alcoholamine is triethanolamine.

[0013] In some embodiments, the weight ratio of the strong base, the carbon-sulfur double bond-containing compound, and the alcohol amine is 1:2.3-2.7:0.8-1.3.

[0014] In some embodiments, the conditions of mixing I include at least: a temperature of 10-30° C. and a time of 1-3 h.

[0015] In some embodiments, in step (1), the alginate is sodium alginate and / or potassium alginate, preferably sodium alginate.

[0016] In some embodiments, the water-soluble cadmium salt is selected from at least one of cadmium nitrate, cadmium chloride, cadmium sulfate, and cadmium acetate.

[0017] In some embodiments, the weight ratio of alginate to water-soluble cadmium salt is 1:0.25-0.75.

[0018] In some embodiments, the conditions of mixing II include at least: a temperature of 70-80° C. and a time of 1-2 h.

[0019] In some embodiments, in step (2), the conditions of mixing III at least include: the sulfur-containing ligand is added dropwise to the alginate-cadmium ion chelate in the form of a solution at a temperature of 70-80° C. for 4-6 hours.

[0020] In some embodiments, the dripping conditions include at least: a dripping speed of 30-50 drops / min.

[0021] In some embodiments, the method further comprises: separating and purifying the reaction solution obtained by mixing III in step (2).

[0022] In some embodiments, the separation process includes: subjecting the reaction liquid to solid-liquid separation I, and subjecting the liquid obtained by solid-liquid separation I to alcohol precipitation I.

[0023] In some embodiments, the purification process includes: dissolving the separated crude product in water and then performing solid-liquid separation II, and performing alcohol precipitation II on the supernatant obtained from the solid-liquid separation II.

[0024] The second aspect of the present disclosure provides cadmium sulfide quantum dots obtained by the preparation method described in the first aspect.

[0025] The third aspect of the present disclosure provides the use of the cadmium sulfide quantum dots described in the second aspect in detecting iron ions.

[0026] A fourth aspect of the present disclosure provides a method for detecting iron content, comprising the following steps:

[0027] In step S1, the preparation process of the solution to be tested includes: mixing a glass sample, hydrochloric acid and water to obtain V;

[0028] S2. Measure the fluorescence intensity of the mixed solution obtained by mixing IV.

[0029] According to the present disclosure, a method for detecting iron content uses the cadmium sulfide quantum dots provided in the second aspect as fluorescent probes to measure iron content. This method has good reproducibility, low detection limit, high sensitivity, and is not affected by other elements. It has strong selectivity for fluorescence quenching of iron ions.

[0030] In some embodiments, the preparation process of the glass sample includes: crushing the glass and mixing it with a flux; the flux is lithium tetraborate and / or lithium metaborate.

[0031] In some embodiments, the weight ratio of glass to flux is 1:2-3.

[0032] In some embodiments, the conditions for mixing VI include at least: a temperature of 1050-1150° C. and a time of 8-12 min.

[0033] In some embodiments, the glass crushing process includes: placing the glass in an alumina container, burning it, and then pouring it into water.

[0034] In some embodiments, the method further comprises: measuring the fluorescence intensity of the standard solution and drawing a standard curve, and calculating the iron content in the solution to be tested according to the standard curve.

[0035] Through the above technical scheme, the preparation method of cadmium sulfide photo quantum dots provided by the present disclosure can obtain cadmium sulfide photo quantum dots with stable fluorescence properties through the synergistic effect of sulfur-containing ligands and alginate-cadmium ion chelates. The cadmium sulfide photo quantum dots can produce a fluorescence quenching effect on iron ions, are not easily interfered by other elements, and also reduce the detection limit of iron ions. The trace iron content in glass can be detected with stable detection and small error, and is suitable for industrial production and application. DETAILED DESCRIPTION

[0036] The following embodiments of the present disclosure are further described in detail in conjunction with the examples. The detailed description of the following embodiments is used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms, not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0037] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0038] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0039] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0040] In a first aspect, the present disclosure provides a method for preparing cadmium sulfide quantum dots, the method comprising the following steps:

[0041] (1) mixing a strong base, a carbon-sulfur double bond-containing compound and an alcohol amine to obtain a sulfur-containing ligand; mixing alginate and a water-soluble cadmium salt to obtain an alginate-cadmium ion chelate;

[0042] (2) Mixing the sulfur-containing ligand and alginate-cadmium ion chelate III.

[0043] The inventors of the present disclosure unexpectedly discovered during the research process that through the synergistic effect of sulfur-containing ligands and alginate-cadmium ion chelates, cadmium sulfide quantum dots with stable fluorescence properties can be obtained. The cadmium sulfide quantum dots can produce a fluorescence quenching effect on iron ions, are not easily interfered by other elements, and also reduce the detection limit of iron ions. The trace iron content in glass can be detected with stable detection and small error, and is suitable for industrial production and application.

[0044] According to the present disclosure, in order to further improve the yield of sulfur-containing ligands, in some embodiments, in step (1), the strong base is sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide.

[0045] According to the present disclosure, in order to further improve the yield of sulfur-containing ligands, in some embodiments, the carbon-sulfur double bond-containing compound is selected from at least one of carbon disulfide, thiourea and thioacetamide, preferably carbon disulfide.

[0046] According to the present disclosure, in order to further improve the yield of sulfur-containing ligands, in some embodiments, the alcoholamine is selected from at least one of triethanolamine, diethanolamine and ethanolamine; in some specific embodiments, the alcoholamine is triethanolamine.

[0047] According to the present disclosure, in order to further improve the yield of sulfur-containing ligands, in some embodiments, the weight ratio of the strong base, the carbon-sulfur double bond-containing compound and the alcohol amine is 1:2.3-2.7:0.8-1.3.

[0048] According to the present disclosure, in order to further improve the reaction rate of preparing sulfur-containing ligands and the yield of products, in some embodiments, the conditions of mixing I include at least: the temperature is 10-30°C, specifically 10°C, 20°C, 30°C, or any value between the above two values; the time is 1-3h, specifically 1h, 2h, 3h, or any value between the above two values.

[0049] According to the present disclosure, in order to further improve the reaction rate of preparing sulfur-containing ligands and the yield of products, in some embodiments, the strong base can be first prepared in the form of a solution, and then mixed with the carbon-sulfur double bond compound and the alcohol amine. Exemplarily, the process of mixing I includes: adding 4-8g of the strong base to 100mL of ultrapure water, stirring until the strong base is completely dissolved, and then adding the carbon-sulfur double bond compound and the alcohol amine thereto, stirring at 10-30°C for 1-3h, and the weight ratio of the strong base, the carbon-sulfur double bond compound and the alcohol amine is 1:2.3-2.7:0.8-1.3.

[0050] According to the present disclosure, in some embodiments, in step (1), the alginate is sodium alginate and / or potassium alginate, preferably sodium alginate. The inventors found that in the above embodiments, the chelation rate of alginate-cadmium ions can be improved, thereby improving the stability of the fluorescence properties of cadmium sulfide quantum dots.

[0051] According to the present disclosure, the above substances can all be obtained through commercial purchase.

[0052] According to the present disclosure, in order to further improve the chelation rate of alginate-cadmium ions and the stability of the fluorescence properties of cadmium sulfide quantum dots, in some embodiments, the water-soluble cadmium salt is selected from at least one of cadmium nitrate, cadmium chloride, cadmium sulfate and cadmium acetate.

[0053] According to the present disclosure, in order to further improve the chelation rate of alginate-cadmium ions and the stability of the fluorescence properties of cadmium sulfide quantum dots, in some embodiments, the weight ratio of alginate and water-soluble cadmium salt is 1:0.25-0.75, specifically 1:0.25, 1:0.5, 1:0.75, or any value between the above two values.

[0054] According to the present disclosure, in some embodiments, in order to further improve the reaction rate of preparing alginate-cadmium ions and the yield of the product, the conditions of mixing II include at least: the temperature is 70-80°C, specifically 70°C, 75°C, 80°C, or any value between the foregoing two values; the time is 1-2h, specifically 1h, 1.5h, 2h, or any value between the foregoing two values.

[0055] According to the present disclosure, the sulfur-containing ligand and the alginate-cadmium ion chelate can be mixed and reacted in the form of solutions, or the sulfur-containing ligand can be added dropwise to the alginate-cadmium ion chelate solution in the form of a solution. In order to further improve the reaction rate and product yield of preparing cadmium sulfide light quantum dots, in some embodiments, in step (2), the conditions of mixing III at least include: the sulfur-containing ligand is added dropwise to the alginate-cadmium ion chelate in the form of a solution, the temperature is 70-80°C, specifically 70°C, 75°C, 80°C, or any value between the above two values; the time is 4-6h, specifically 4h, 5h, 6h, or any value between the above two values.

[0056] According to the present disclosure, when the sulfur-containing ligand is added dropwise to the alginate-cadmium ion chelate in the form of a solution, there is no particular restriction on the conditions for the addition. In order to further improve the yield of cadmium sulfide photoquantum dots, in some embodiments, the conditions for the addition include at least: a dropwise addition speed of 30-50 drops / min, specifically 30 drops / min, 40 drops / min, 50 drops / min, or any value between the above two values.

[0057] According to the present disclosure, in order to further improve the yield of preparing cadmium sulfide quantum dots, in some embodiments, the conditions of mixing III also include: a rotation speed of 300-600 rpm, specifically 300 rpm, 400 rpm, 500 rpm, 600 rpm, or any value between the above two values.

[0058] According to the present disclosure, in order to further improve the reaction rate of preparing sulfur-containing ligands and the yield of products, in some embodiments, alginate can be first prepared in the form of a solution and then mixed with a water-soluble cadmium salt. Exemplarily, the process of mixing II includes: adding 4-5.5g of sodium alginate to water based on 100mL of ultrapure water, stirring until the alginate is fully dissolved, and then adding a water-soluble cadmium salt, stirring at a temperature of 70-80°C for 1-2h, and the weight ratio of alginate to water-soluble cadmium salt is 1:0.25-0.75.

[0059] According to the present disclosure, in order to further improve the purity of cadmium sulfide quantum dots, in some embodiments, the method further includes: separating and purifying the reaction solution obtained by mixing III in step (2).

[0060] According to the present disclosure, in order to further improve the purity of cadmium sulfide quantum dots, in some embodiments, the separation process includes: performing solid-liquid separation I on the reaction liquid, and performing alcohol precipitation I on the liquid obtained by solid-liquid separation I.

[0061] According to the present disclosure, in order to further improve the purity of cadmium sulfide quantum dots, in some embodiments, the purification process includes: dissolving the separated crude product in water and then performing solid-liquid separation II, and performing alcohol precipitation II on the supernatant obtained from solid-liquid separation II.

[0062] According to the present disclosure, solid-liquid separation I and solid-liquid separation II can be independently selected from solid-liquid separation methods such as filtration, suction filtration, and centrifugation. In some embodiments, solid-liquid separation I and solid-liquid separation II are both centrifugal separations. The conditions of solid-liquid separation I include: a rotation speed of 6000-10000 rpm and a time of 5-10 min; the conditions of solid-liquid separation II include: a rotation speed of 6000-10000 rpm and a time of 5-10 min.

[0063] According to the present disclosure, the alcohol used in alcohol precipitation I and alcohol precipitation II can be methanol or ethanol respectively.

[0064] Exemplarily, the process of alcohol precipitation I includes: centrifuging the reaction solution, collecting the supernatant after centrifugation, mixing the supernatant with ethanol at a weight ratio of 1:2-4 and stirring for 20-40 minutes, centrifuging the mixed solution, pouring out the supernatant after centrifugation, and collecting the residual solid for drying.

[0065] Illustratively, the process of alcohol precipitation II includes: dissolving the separated crude product in water and then centrifuging it, collecting the supernatant after centrifugation, mixing the supernatant with ethanol at a weight ratio of 1:2-4 and stirring for 20-40 minutes, centrifuging the mixture, pouring out the supernatant after centrifugation, and collecting the remaining solid for drying.

[0066] According to the present disclosure, drying can be a conventional drying method in the art, such as forced air drying or vacuum drying. In some embodiments, the drying method is vacuum drying, and the drying conditions include: a temperature of 80-120° C. and a time of 8-12 hours.

[0067] According to the present disclosure, in order to further improve the purity of cadmium sulfide quantum dots, the purification may be performed 2-4 times.

[0068] The second aspect of the present disclosure provides cadmium sulfide quantum dots obtained by the preparation method provided in the first aspect.

[0069] The third aspect of the present disclosure provides the use of the cadmium sulfide quantum dots provided in the second aspect in detecting iron ions.

[0070] According to the present disclosure, the cadmium sulfide quantum dots provided in the second aspect have stable fluorescence properties. When combined with iron ions, they will produce fluorescence quenching phenomenon, and are not interfered by other elements. The detection limit of iron ions is also reduced, and the trace iron content in glass can be detected, which is suitable for industrial production and application.

[0071] A fourth aspect of the present disclosure provides a method for detecting iron content, comprising the following steps:

[0072] In step S1, the preparation process of the solution to be tested includes: mixing a glass sample, hydrochloric acid and water to obtain V;

[0073] S2. Measure the fluorescence intensity of the mixed solution obtained by mixing IV.

[0074] According to the present disclosure, a method for detecting iron content uses the cadmium sulfide quantum dots provided in the second aspect as fluorescent probes to measure iron content. This method has good reproducibility, low detection limit, high sensitivity, and is not affected by other elements. It has strong selectivity for fluorescence quenching of iron ions.

[0075] According to the present disclosure, in some embodiments, in step S1, the concentration of cadmium sulfide quantum dots in the mixed solution obtained by mixing IV is 1-3 g / L.

[0076] According to the present disclosure, in some embodiments, in step S1, the preparation process of the test solution includes: mixing a glass sample, hydrochloric acid and water.

[0077] According to the present disclosure, hydrochloric acid is a hydrochloric acid aqueous solution with a hydrochloric acid concentration of 3-5wt%. The weight ratio of the glass sample to the hydrochloric acid is 1:40-60. Exemplarily, the process of mixing V includes: taking 20-30mL of water, adding 4-6mL of hydrochloric acid, and then adding 0.1g of the powder of the glass sample to the above solution, shaking until the powder of the glass sample is completely dissolved, and finally adjusting the volume to 100mL, shaking well and then testing.

[0078] According to the present disclosure, in some embodiments, the preparation process of the glass sample includes: crushing the glass and mixing it with a flux; the flux is lithium tetraborate and / or lithium metaborate. In the above embodiment, lithium tetraborate and / or lithium metaborate are used as flux to digest the glass, which can avoid the use of highly volatile acids such as hydrofluoric acid or perchloric acid, avoid the low test value caused by the fuming of volatile acids and iron, and can oxidize trace divalent iron into trivalent iron, thereby improving the accuracy of iron content detection.

[0079] According to the present disclosure, in order to further improve the accuracy of iron content detection, in some embodiments, the flux is lithium tetraborate and lithium metaborate, and the weight ratio of lithium tetraborate to lithium metaborate is 2-4:1.

[0080] According to the present disclosure, in order to further improve the accuracy of iron content detection, in some embodiments, the weight ratio of glass to flux is 1:2-3, specifically 1:2, 1:2.5, 1:3, or any value between the aforementioned two values.

[0081] According to the present disclosure, in order to improve the digestion effect on glass, in some embodiments, the conditions of mixing VI include at least: the temperature is 1050-1150°C, specifically 1050°C, 1100°C, 1150°C, or any value between the above two values; the time is 8-12min, specifically 8min, 10min, 12min, or any value between the above two values.

[0082] According to the present disclosure, in order to improve the digestion effect of glass, in some embodiments, the glass crushing process includes: placing the glass in an alumina container, burning it, and then pouring it into water. In the above embodiment, it is possible to avoid the introduction of iron ions due to the use of iron-containing tools, thereby improving the accuracy of iron content detection.

[0083] Exemplarily, the glass crushing process includes: placing the glass to be tested into an alumina crucible, burning it in an alcohol burner for 3-5 minutes, and then quickly pouring it into water. The glass is broken due to "sudden cooling". The above operation is repeated until the fragments are of appropriate size, and then the glass fragments are ground in a mortar until the particle size is less than 100 μm.

[0084] According to the present disclosure, in order to improve the accuracy of detection, in some embodiments, the glass frit obtained by mixing VI can be broken, and the process of breaking the glass frit includes: placing the glass frit in an alumina container, burning it, and then pouring it into water.

[0085] In some embodiments, the method further comprises: measuring the fluorescence intensity of the standard solution and drawing a standard curve, and calculating the iron content in the solution to be tested according to the standard curve.

[0086] According to the present disclosure, the preparation process of the standard solution includes: adding 4-6mL of hydrochloric acid to a 100mL volumetric flask to prepare solutions with iron ion concentrations of 0ppm, 20ppm, 40ppm, 60ppm, and 80ppm respectively; preparing a cadmium sulfide quantum dot solution with a concentration of 1-3g / L; taking 10mL of the above-mentioned iron ion solutions of different concentrations and mixing them with the same volume of cadmium sulfide quantum dot solution, and then measuring the fluorescence intensity thereof to obtain the relationship y=ax+b between the fluorescence intensity (y) and the iron content concentration (x), and obtaining the values ​​of a and b through linear fitting of the above data.

[0087] According to the present disclosure, in order to further improve the accuracy of iron content detection, in some embodiments, ultrapure water is used.

[0088] According to a particularly preferred embodiment of the present disclosure, a method for preparing cadmium sulfide light quantum dots is provided, comprising the following steps:

[0089] Preparation of cadmium sulfide quantum dots:

[0090] (1) mixing a strong base, a carbon-sulfur double bond-containing compound and an alcohol amine at a temperature of 10-30° C. for 1-3 hours to obtain a sulfur-containing ligand; mixing alginate and a water-soluble cadmium salt at a temperature of 70-80° C. for 1-2 hours to obtain an alginate-cadmium ion chelate;

[0091] (2) adding the sulfur-containing ligand in the form of a solution into the alginate-cadmium ion chelate at a rate of 30-50 drops / min, and mixing at a temperature of 70-80° C. for 4-6 hours;

[0092] (3) separating and purifying the reaction liquid obtained in step (2), wherein the separation process comprises: subjecting the reaction liquid to solid-liquid separation I, and subjecting the liquid obtained in solid-liquid separation I to alcohol precipitation I; and the purification process comprises: dissolving the crude product obtained in the separation in water and then subjecting the crude product to solid-liquid separation II, and subjecting the supernatant obtained in the solid-liquid separation II to alcohol precipitation II;

[0093] The strong base is sodium hydroxide, the compound containing a carbon-sulfur double bond is carbon disulfide, the alcohol amine is triethanolamine, and the weight ratio of the strong base, the compound containing a carbon-sulfur double bond and the alcohol amine is 1:2.3-2.7:0.8-1.3; the alginate is sodium alginate, the water-soluble cadmium salt is selected from at least one of cadmium nitrate, cadmium chloride, cadmium sulfate and cadmium acetate, and the weight ratio of the alginate to the water-soluble cadmium salt is 1:0.25-0.75;

[0094] The method for determining the iron content comprises the following steps:

[0095] S1, mixing the solution to be tested and the cadmium sulfide quantum dots to obtain a mixed solution;

[0096] S2, measuring the fluorescence intensity of the mixed solution;

[0097] S3, measuring the fluorescence intensity of the standard solution and drawing a standard curve, and calculating the iron content in the solution to be tested according to the standard curve;

[0098] The preparation process of the test solution includes: mixing the glass sample, hydrochloric acid and water;

[0099] The preparation process of the glass sample includes: placing the glass in an alumina container, burning it, and then pouring it into water to obtain broken glass, mixing the broken peeled glass with a solvent at a temperature of 1050-1150°C for 8-12 minutes;

[0100] The flux is lithium tetraborate and / or lithium metaborate, and the weight ratio of glass to flux is 1:2-3.

[0101] The cadmium sulfide photonic quantum dots prepared by the above particularly preferred embodiment can produce a fluorescence quenching effect on iron ions, are not easily interfered by other elements, and also reduce the detection limit of iron ions. It can detect the trace iron content in glass with stable detection and small error, and is suitable for industrial production and application.

[0102] The present disclosure will be described in detail below through examples.

[0103] In the following examples, carbon disulfide was purchased from Sinopharm Chemical Reagent Co., Ltd.; sodium alginate was purchased from Sinopharm Chemical Reagent Co., Ltd.; the glass was photovoltaic glass purchased from Tianjin Parkson Glass Co., Ltd., model AR-TPV-3.2, and the iron content in the photovoltaic glass was 50 ppm; unless otherwise specified, other raw materials were commercially available.

[0104] In the following examples, the spectrophotometer was purchased from Shimadzu Corporation, model UV-1900; the automatic melting machine was purchased from Luoyang Haina Testing Instrument Co., Ltd., model L6.

[0105] Preparation Example A1

[0106] (1) Preparation of sulfur-containing ligand: 6 g of NaOH was added to 100 mL of ultrapure water, and the mixture was stirred until the NaOH was completely dissolved. Then, CS2 was added, and the mass of the added CS2 was 2.5 times the mass of NaOH. Then, triethanolamine was added, and the mass of triethanolamine was the same as that of NaOH. The mixture was stirred magnetically at 20° C. and 500 rpm for 2 h to obtain reaction solution I.

[0107] (2) Preparation of alginate-cadmium ion chelate: Based on 100 mL of ultrapure water, 5 g of sodium alginate was added to the water and stirred until the sodium alginate was fully dissolved. Then, 2 g of cadmium nitrate was added and the temperature was controlled at 75° C. and magnetic stirring was performed at 500 rpm for 1.5 h to allow the sodium alginate to fully chelate the cadmium ions, thereby obtaining a reaction solution II.

[0108] (3) Add reaction liquid I to reaction liquid II, stirring while adding, controlling the dripping speed of reaction liquid I to 40 drops / min, and magnetically stirring at 500 rpm for 5 h at a temperature of 75° C. to obtain reaction liquid III; place reaction liquid III at room temperature until reaction liquid III cools to room temperature; centrifuge reaction liquid III, and collect the supernatant after centrifugation; put the supernatant into a clean beaker, magnetically stir at 500 rpm, add anhydrous ethanol while stirring, the volume of anhydrous ethanol added is 3 times that of the supernatant, and then continue stirring for 30 min; after the stirring is completed, centrifuge, pour off the supernatant, collect the residual solid, put it into a vacuum drying oven and dry it for 10 h to obtain a crude product;

[0109] (4) Purifying the crude product: dissolving the crude product obtained in step (3) in 100 mL of ultrapure water, magnetically stirring at 500 rpm for 20 min at room temperature, then centrifuging, collecting the supernatant, and discarding the solid residue; magnetically stirring the supernatant at 500 rpm, adding 3 times the volume of anhydrous ethanol, stirring for another 30 min, centrifuging, discarding the supernatant, collecting the precipitate and drying it in a vacuum drying oven for 10 h; repeating the purification process twice according to the above steps to obtain nano-cadmium sulfide light quantum dots with uniform particle size, good fluorescence performance, and high selectivity for iron ions.

[0110] Preparation Example A2

[0111] (1) Preparation of sulfur-containing ligand: 4 g of NaOH was added to 100 mL of ultrapure water, and the mixture was stirred until the NaOH was completely dissolved. Then, CS2 was added, and the mass of the added CS2 was 2.3 times the mass of NaOH. Then, triethanolamine was added, and the mass of the triethanolamine was 0.8 times the mass of NaOH. The mixture was stirred magnetically at 10° C. for 1 h to obtain reaction solution I.

[0112] (2) Preparation of alginate-cadmium ion chelate: Based on 100 mL of ultrapure water, 4 g of sodium alginate was added to the water and stirred until the sodium alginate was fully dissolved. Then, 1.5 g of cadmium chloride was added and the temperature was controlled at 70° C. and magnetic stirring was performed at 300 rpm for 1 h to allow the sodium alginate to fully chelate the cadmium ions, thereby obtaining a reaction solution II.

[0113] (3) Add reaction liquid I to reaction liquid II, stirring while adding, controlling the dripping speed of reaction liquid I to 30 drops / min, and magnetically stirring at 300 rpm for 4 h at a temperature of 70°C to obtain reaction liquid III; leaving reaction liquid III at room temperature until reaction liquid III cools to room temperature; centrifuging reaction liquid III, and collecting the supernatant after centrifugation; placing the supernatant in a clean beaker, magnetically stirring at 300 rpm, adding anhydrous ethanol while stirring, the volume of anhydrous ethanol added being twice that of the supernatant, and then continuing to stir for 20 min; after the stirring is completed, centrifuge, pour off the supernatant, collect the residual solid, put it in a vacuum drying oven and dry it for 8 h to obtain a crude product;

[0114] (4) Purifying the crude product: dissolving the crude product obtained in step (3) in 100 mL of ultrapure water, magnetically stirring at 300 rpm for 20 min at room temperature, then centrifuging, collecting the supernatant, and discarding the solid residue; magnetically stirring the supernatant at 300 rpm, adding 2 times the volume of anhydrous ethanol, stirring for another 20 min, centrifuging, discarding the supernatant, collecting the precipitate and drying it in a vacuum drying oven for 8 h; repeating the purification process three times according to the above steps to obtain nano-cadmium sulfide light quantum dots with uniform particle size, good fluorescence performance, and high selectivity for iron ions.

[0115] Preparation Example A3

[0116] (1) Preparation of sulfur-containing ligand: 8 g of NaOH was added to 100 mL of ultrapure water, and the mixture was stirred until the NaOH was completely dissolved. Then, CS2 was added, and the mass of the added CS2 was 2.7 times the mass of NaOH. Then, triethanolamine was added, and the mass of the triethanolamine was 2.7 times the mass of NaOH. The mixture was stirred at 30° C. and 600 rpm for 3 h to obtain reaction solution I.

[0117] (2) Preparation of alginate-cadmium ion chelate: Based on 100 mL of ultrapure water, 5.5 g of sodium alginate was added to the water and stirred until the sodium alginate was fully dissolved. Then, 3 g of cadmium nitrate was added and the temperature was controlled at 80° C. and magnetic stirring was performed at 600 rpm for 2 h to allow the sodium alginate to fully chelate the cadmium ions, thereby obtaining a reaction solution II.

[0118] (3) Add reaction liquid I to reaction liquid II, stirring while adding, controlling the dripping speed of reaction liquid I to 50 drops / min, and magnetically stirring at 600 rpm for 6 hours at a temperature of 80°C to obtain reaction liquid III; leaving reaction liquid III at room temperature until reaction liquid III cools to room temperature; centrifuging reaction liquid III, and collecting the supernatant after centrifugation; placing the supernatant in a clean beaker, magnetically stirring at 600 rpm, adding anhydrous ethanol while stirring, the volume of anhydrous ethanol added being 4 times that of the supernatant, and then continuing to stir for 40 minutes; after the stirring is completed, centrifuge, pour off the supernatant, collect the residual solid, put it in a vacuum drying oven and dry it for 12 hours to obtain a crude product;

[0119] (4) Purifying the crude product: dissolving the crude product obtained in step (3) in 100 mL of ultrapure water, magnetically stirring at 600 rpm for 30 min at room temperature, then centrifuging, collecting the supernatant, and discarding the solid residue; magnetically stirring the supernatant at 600 rpm, adding 4 times the volume of anhydrous ethanol, stirring for another 40 min, centrifuging, discarding the supernatant, collecting the precipitate and drying it in a vacuum drying oven for 12 h; repeating the purification process three times according to the above steps to obtain nano-cadmium sulfide light quantum dots with uniform particle size, good fluorescence performance, and high selectivity for iron ions.

[0120] Preparation Example A4

[0121] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that the mass of CS2 was replaced by 1.5 times the mass of NaOH, and the mass of triethanolamine was replaced by 2 times the mass of NaOH.

[0122] Preparation Example A5

[0123] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that NaOH was replaced by KOH, CS2 was replaced by thiourea, and triethanolamine was replaced by ethanolamine.

[0124] Preparation Example A6

[0125] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that the mass of cadmium nitrate was replaced with 5 g.

[0126] Preparation Example A7

[0127] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that step (4) was not performed, that is, the crude product obtained in step (3) was not purified.

[0128] Preparation Example B1

[0129] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that sodium alginate was replaced by citric acid.

[0130] Preparation Example B2

[0131] Cadmium sulfide quantum dots were prepared according to the method of Preparation Example A1, except that CS2 was replaced by Na2S.

[0132] Preparation Example B3

[0133] Commercially available cadmium sulfide quantum dots were purchased from Shanghai Yuanmu Biotechnology Co., Ltd., model number: 3801306-23-6.

[0134] Example 1

[0135] (1) Using the "sudden cooling" method to break the glass: Put the photovoltaic glass into an alumina crucible, burn it in an alcohol blowtorch for 3 minutes, and then quickly pour it into pure water. The glass will break due to "sudden cooling". Repeat the above breaking operation until the fragments are of appropriate size, and then grind the glass fragments in a mortar to grind them into glass powder with a particle size of less than 100 μm; take 1.0000g of the above glass powder, add 2g of mixed flux (the mixed flux is lithium tetraborate and lithium metaborate with a mass ratio of 3:1), and the amount should be accurate to 0.0001g. After stirring and mixing, melt the sample in an automatic melting machine and heat it. The temperature is set to 1100℃, and the automatic melting time is set to 10min. After melting the sample, the mass of the fused piece is accurately weighed to 0.0001g, recorded as m. The fused piece is ground into glass powder of less than 100μm according to the above-mentioned crushing and grinding methods, and one tenth of the mass m is weighed, recorded as m1. The glass powder of mass m1 contains 0.1000g of glass sample. Take 20mL of water, add 5mL of hydrochloric acid, and then add the glass powder of mass m1 to the above solution, shake until the glass powder is completely dissolved, and finally adjust the volume to 100mL. After shaking well, the solution to be tested is obtained.

[0136] (2) Add 5 mL of hydrochloric acid to a 100 mL volumetric flask to prepare 0 ppm, 20 ppm, 40 ppm, 60 ppm, and 80 ppm iron standard solutions, respectively. Dissolve 0.05 g of the cadmium sulfide quantum dots prepared in Preparation Example A1 in 50 mL of ultrapure water and stir thoroughly until the cadmium sulfide quantum dots are completely dissolved in the water. Take 10 mL of each of the above-prepared series of iron standard solutions and add them to the cadmium sulfide quantum dot solution, stir thoroughly for 20 min, and then use a spectrophotometer to measure the fluorescence intensity at 630 nm. According to the test results, a standard curve y=ax+b was fitted, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.1739, b=2387.6728, and its detection limit is 1×10 -5 mol / L, detection range is 1×10 -4 -2×10 -3mol / L; the fluorescence intensity of the test solution was determined according to the above steps, the iron concentration in the test solution was obtained according to the above standard curve, and then the iron content in the photovoltaic glass was calculated. The results are shown in Table 1.

[0137] Example 2

[0138] (1) Using the "sudden cooling" method to break the glass: Put the photovoltaic glass into an alumina crucible, burn it in an alcohol blowtorch for 5 minutes, and then quickly pour it into pure water. The glass will break due to "sudden cooling". Repeat the above breaking operation until the fragments are of appropriate size, and then grind the glass fragments in a mortar to grind them into glass powder with a particle size of less than 100 μm; take 1.0000g of the above glass powder, add 3g of mixed flux (the mixed flux is lithium tetraborate and lithium metaborate with a mass ratio of 2:1), and the amount should be accurate to 0.0001g. After stirring and mixing, melt the sample in an automatic melting machine. The temperature is set to 1050℃, and the automatic melting time is set to 12min. After melting the sample, the mass of the fused piece is accurately weighed to 0.0001g, recorded as m. The fused piece is ground into glass powder of less than 100μm according to the above-mentioned crushing and grinding methods, and m1=0.1000g is weighed. There is 0.1000g of glass sample in the glass powder of mass m1. Take 20mL of water, add 5mL of hydrochloric acid, and then add the glass powder of mass m1 to the above solution, shake until the glass powder is completely dissolved, and finally adjust the volume to 100mL. After shaking well, the solution to be tested is obtained.

[0139] (2) Add 5 mL of hydrochloric acid to a 100 mL volumetric flask to prepare 0 ppm, 20 ppm, 40 ppm, 60 ppm, and 80 ppm iron standard solutions, respectively. Dissolve 0.1 g of the cadmium sulfide light quantum dots prepared in Preparation Example A2 in 50 mL of ultrapure water and stir thoroughly until the cadmium sulfide light quantum dots are completely dissolved in the water. Take 10 mL of each of the above-prepared series of iron standard solutions and add them to the cadmium sulfide light quantum dot solution, stir thoroughly for 20 min, and then use a spectrophotometer to measure the fluorescence intensity at 630 nm. According to the test results, a standard curve y=ax+b was fitted, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.2476, b=1375.4524, and its detection limit is 1×10 -5 mol / L, detection range is 1×10 -4 -2×10 -3 mol / L; the fluorescence intensity of the test solution was determined according to the above steps, the iron concentration in the test solution was obtained according to the above standard curve, and then the iron content in the photovoltaic glass was calculated. The results are shown in Table 1.

[0140] Example 3

[0141] (1) Using the "sudden cooling" method to break the glass: Put the photovoltaic glass into an alumina crucible, burn it in an alcohol blowtorch for 5 minutes, and then quickly pour it into pure water. The glass will break due to "sudden cooling". Repeat the above breaking operation until the fragments are of appropriate size, and then grind the glass fragments in a mortar to grind them into glass powder with a particle size of less than 100 μm; take 1.0000g of the above glass powder, add 2g of mixed flux (the mixed flux is lithium tetraborate and lithium metaborate with a mass ratio of 4:1), and the amount should be accurate to 0.0001g. After stirring and mixing, melt the sample in an automatic melting machine, and set the temperature to 1150℃, automatic melting time is set to 8min; after melting the sample, accurately weigh the mass of the fused piece, accurate to 0.0001g, recorded as m, grind the fused piece into glass powder below 100μm according to the above-mentioned crushing and grinding method, weigh one tenth of the mass m, recorded as m1=0.1000g, and there is 0.1000g of glass sample in the mass m1 glass powder; take 20mL of water, add 5mL of hydrochloric acid, and then add the mass m1 glass powder to the above solution, shake until the glass powder is completely dissolved, and finally make the volume to 100mL, shake well to obtain the solution to be tested;

[0142] (2) Add 5 mL of hydrochloric acid to a 100 mL volumetric flask to prepare 0 ppm, 20 ppm, 40 ppm, 60 ppm, and 80 ppm iron standard solutions, respectively. Dissolve 0.15 g of the cadmium sulfide light quantum dots prepared in Preparation Example A3 in 50 mL of ultrapure water and stir thoroughly until the cadmium sulfide light quantum dots are completely dissolved in the water. Take 10 mL of each of the above-prepared series of iron standard solutions and add them to the cadmium sulfide light quantum dot solution, stir thoroughly for 20 min, and then use a spectrophotometer to measure the fluorescence intensity at 630 nm. According to the test results, a standard curve y=ax+b was fitted, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.1653, b=1987.3482, and its detection limit is 2×10 -5 mol / L, detection range is 2×10 -4 -3×10 -3 mol / L; the fluorescence intensity of the test solution was determined according to the above steps, the iron concentration in the test solution was obtained according to the above standard curve, and then the iron content in the photovoltaic glass was calculated. The results are shown in Table 1.

[0143] Example 4

[0144] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example A4.

[0145] Example 5

[0146] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example A5.

[0147] Example 6

[0148] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example A6.

[0149] Example 7

[0150] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example A7.

[0151] Example 8

[0152] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that step (1) was replaced by:

[0153] (1) Use the "sudden cooling" method to break the glass: put the photovoltaic glass into an alumina crucible, burn it in an alcohol blowtorch for 3 minutes, and then quickly pour it into pure water. The glass will break due to "sudden cooling". Repeat the above breaking operation until the fragments are of appropriate size, and then grind the glass fragments in a mortar to grind them into glass powder with a particle size of less than 100 μm; take 20 mL of water, add 5 mL of hydrochloric acid, and then add 0.1000 g of glass powder to the above solution, shake until the glass powder is completely dissolved, and finally make the volume to 100 mL. After shaking, the test solution is obtained.

[0154] Comparative Example 1

[0155] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example B1.

[0156] The standard curve is y=ax+b, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.06543, b=987.673, and the detection limit is 1×10 -3 mol / L, detection range is 1×10 -2 -1×10 -1 mol / L.

[0157] Comparative Example 2

[0158] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced by the cadmium sulfide quantum dots prepared in Preparation Example B2.

[0159] The standard curve is y=ax+b, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.09873, b=1076.3481, and the detection limit is 2×10 -3 mol / L, detection range is 2×10 -2 -1×10 -1 mol / L.

[0160] Comparative Example 3

[0161] The iron content in the photovoltaic glass was detected according to the method of Example 1, except that the cadmium sulfide quantum dots were replaced with the cadmium sulfide quantum dots provided in Preparation Example B3.

[0162] The standard curve is y=ax+b, where y is the fluorescence intensity of iron, x is the concentration of iron, a=0.1198, b=1527.8719, and its detection limit is 1×10 -3 mol / L, detection range is 5×10 -3 -5×10 -2 mol / L.

[0163] Test Example 1

[0164] After testing the iron content in the samples of Example 1 to Example 8 and Comparative Examples 1 to Comparative Examples 3, the iron content in the glass was obtained. The results are shown in Table 1.

[0165] Table 1

[0166]

[0167] It can be seen from the results of Table 1 that, compared with Comparative Examples 1 to 3, when using the method provided by the present disclosure to test the iron content of photovoltaic glass with an actual iron content of 50 ppm, Examples 1 to 8 have a smaller error and higher precision. Among them, the measurement results of the iron content in photovoltaic glass in Examples 1 to 3 are within ±1% of the actual value, the measurement results of Examples 4 to 8 are within ±11% of the actual value, and the measurement results of Comparative Examples 1 to 3 are more than 60% higher than the actual value. From the above data, it can be obtained that the measurement results of Examples 1 to 8 deviate less from the actual value, among which the measurement results of Examples 1 to 3 deviate the least from the actual value, and the error is small; while the data in Comparative Examples 1 to 3 are obviously larger than the actual value, the error is large, and it is not suitable for the detection of trace iron content in photovoltaic glass.

[0168] Test Example 2

[0169] After 20 parallel tests were conducted on the iron content in the sample to be tested using the method in Example 1, the iron content in the glass was determined. The results are shown in Table 2.

[0170] Table 2

[0171]

[0172]

[0173] It can be seen from the data in Table 2 that the relative standard deviation of the data is 3.76% <5%, and the repeatability is good, indicating that this method is extremely stable in the determination of trace iron, especially when the content is below 100 ppm, and the method has good repeatability, and can be used for the determination of trace iron in photovoltaic glass.

[0174] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0175] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A method for preparing cadmium sulfide quantum dots, characterized in that: The method comprises the following steps: (1) mixing a strong base, a carbon-sulfur double bond-containing compound and an alcohol amine to obtain a sulfur-containing ligand; mixing alginate and a water-soluble cadmium salt to obtain an alginate-cadmium ion chelate; (2) Mixing the sulfur-containing ligand and the alginate-cadmium ion chelate III.

2. The preparation method according to claim 1, characterized in that: In step (1), the strong base is sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide; Preferably, the carbon-sulfur double bond-containing compound is selected from at least one of carbon disulfide, thiourea and thioacetamide, and more preferably carbon disulfide; Preferably, the alcoholamine is selected from at least one of triethanolamine, diethanolamine and ethanolamine, and more preferably triethanolamine; Preferably, the weight ratio of the strong base, the carbon-sulfur double bond-containing compound and the alcoholamine is 1:2.3-2.7:0.8-1.3; Preferably, the mixing conditions I include at least: a temperature of 10-30° C. and a time of 1-3 h.

3. The preparation method according to claim 1, characterized in that: In step (1), the alginate is sodium alginate and / or potassium alginate, preferably sodium alginate; Preferably, the water-soluble cadmium salt is selected from at least one of cadmium nitrate, cadmium chloride, cadmium sulfate and cadmium acetate; Preferably, the weight ratio of the alginate to the water-soluble cadmium salt is 1:0.25-0.75; Preferably, the conditions of mixing II at least include: temperature of 70-80° C. and time of 1-2 h.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step (2), the conditions of the mixing III at least include: the sulfur-containing ligand is added dropwise to the alginate-cadmium ion chelate in the form of a solution at a temperature of 70-80° C. for 4-6 hours; Preferably, the dripping conditions at least include: a dripping speed of 30-50 drops / min.

5. The preparation method according to any one of claims 1 to 3, characterized in that: The method further comprises: separating and purifying the reaction solution obtained by mixing III in step (2); Preferably, the separation process comprises: performing solid-liquid separation I on the reaction liquid, and performing alcohol precipitation I on the liquid obtained by the solid-liquid separation I; Preferably, the purification process comprises: dissolving the crude product obtained by separation in water and then performing solid-liquid separation II, and performing alcohol precipitation II on the supernatant obtained by the solid-liquid separation II.

6. Cadmium sulfide quantum dots obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the cadmium sulfide optical quantum dots according to claim 6 in detecting iron ions.

8. A method for detecting iron content, characterized in that: The following steps are involved: S1, mixing the solution to be tested and the cadmium sulfide light quantum dots according to claim 6 IV; S2. Measure the fluorescence intensity of the mixed solution obtained by mixing IV.

9. The method according to claim 8, characterized in that In step S1, the preparation process of the test solution includes: mixing a glass sample, hydrochloric acid and water; Preferably, the preparation process of the glass sample comprises: crushing the glass and mixing it with a flux; the flux is lithium tetraborate and / or lithium metaborate; Preferably, the weight ratio of the glass to the flux is 1:2-3; Preferably, the conditions for mixing VI include at least: temperature of 1050-1150°C and time of 8-12 min; Preferably, the glass crushing process comprises: placing the glass in an alumina container, burning it and then pouring it into water.

10. The method according to claim 8, characterized in that The method further comprises: measuring the fluorescence intensity of the standard solution and drawing a standard curve, and calculating the iron content in the solution to be tested according to the standard curve.

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