A carbon quantum dot of vinasse and a preparation method and application thereof

Abstract

The application discloses a kind of distiller's grains carbon quantum dots and preparation method and application thereof.A kind of preparation method of distiller's grains carbon quantum dots, comprising the following steps: distiller's grains centrifugal supernatant is removed to obtain solid, solid is added solvent and is configured into mixture, after ultrasonic, it is placed in reaction kettle and heated, after reaction, filtration is obtained described distiller's grains carbon quantum dots.Distiller's grains as a kind of commercialized product waste, low cost, easy to obtain, while higher safety, distiller's grains as food waste with rich carbon source, under hydrothermal reaction condition, form quantum dots, both can make the cost of preparation quantum dots reduce, can form quantum dots with higher fluorescence intensity again.Using Fe 3+ And the fluorescence quenching effect of distiller's grains carbon quantum dots, realize the analysis detection of Fe 3+ Concentration in soy sauce, reduce detection cost, realize energy saving and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of carbon quantum dots, specifically to a type of carbon quantum dot made from distiller's grains, its preparation method, and its applications. Background Technology

[0002] Carbon quantum dots possess excellent photostability and are also environmentally friendly and low in toxicity, thus attracting widespread attention from researchers. However, applying carbon quantum dots to the food industry places higher demands on their safety. Food waste is a type of material rich in carbon sources that is easily overlooked; therefore, the efficient utilization of food waste is an important research topic.

[0003] Currently, the main techniques for detecting iron ions include atomic absorption spectrometry, ion chromatography, spectrophotometry, and liquid chromatography. However, these methods all share some common drawbacks, such as complex instrumentation, cumbersome sample preparation procedures, and high costs, which limit their application in real-world scenarios. Therefore, developing a rapid, sensitive, and low-cost method for detecting iron ions is of great significance for practical applications. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides carbon quantum dots from distiller's grains, their preparation method, and applications. This invention uses distiller's grains as raw material and synthesizes carbon quantum dots from distiller's grains via a hydrothermal method, achieving the synthesis of Fe... 3+ The prepared carbon quantum dots emitted blue fluorescence upon the addition of Fe. 3+ Subsequently, dynamic fluorescence quenching occurs. Based on this, carbon quantum dots are loaded onto filter paper strips for the purpose of quenching Fe. 3+ The portable detection method was also used, and carbon quantum dots were used to detect the iron content in iron-fortified soy sauce. Using carbon quantum dots from fermented grains as a fluorescent probe has certain advantages: (1) Compared with the reported fluorescent probes, this probe has a comparable LOD and a relatively wide linear range; (2) This probe is synthesized from industrial food waste, which is more environmentally friendly and safer than probes synthesized or doped with chemicals; (3) This is the first time that carbon quantum dots from fermented grains have been used as a probe for Fe 3+ This discovery expands the application of food waste in testing. Therefore, carbon quantum dots from distiller's grains have broad application prospects.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of this invention provides a method for preparing carbon quantum dots from distiller's grains, comprising the following steps:

[0007] The supernatant was removed by centrifugation of the distiller's grains to obtain solids. The solids were added to a solvent to prepare a mixture, which was then sonicated and placed in a reaction vessel for heating. After the reaction, the mixture was filtered to obtain the carbon quantum dots from the distiller's grains.

[0008] Preferably, the solvent is deionized water.

[0009] Preferably, the concentration of the mixture is 3-15 wt%.

[0010] Preferably, the heating temperature in the reactor is 120-240℃, and the heating time is 2-16h.

[0011] Preferably, the lees are lees from rice wine.

[0012] A second aspect of the present invention provides a carbon quantum dot from distiller's grains, which is prepared by the aforementioned method for preparing carbon quantum dots from distiller's grains.

[0013] The third aspect of this invention provides the application of the aforementioned carbon quanta from distiller's grains in the detection of iron ions.

[0014] A fourth aspect of the present invention provides a test strip for detecting iron ions, the test strip being cellulose filter paper loaded with carbon quantum dots; the carbon quantum dots being the aforementioned distillers' grains carbon quantum dots.

[0015] The fifth aspect of the present invention provides a method for preparing a test strip for detecting iron ions, comprising the following steps: cutting cellulose filter paper to the required size, then immersing it in a solution of carbon quantum dots from distillers' grains, and then removing it and drying it at room temperature.

[0016] Preferably, the cellulose filter paper is cut to a size of 5cm × 1cm.

[0017] Preferably, the cellulose filter paper is soaked in the distillers' grains carbon quantum dot solution for 4-6 minutes.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] Distillery lees, as a waste product from commercial production, is inexpensive, readily available, and relatively safe. As a food waste rich in carbon, distillery lees can be used to form quantum dots under hydrothermal reaction conditions. This approach reduces the cost of quantum dot preparation while producing quantum dots with high fluorescence intensity. Utilizing Fe... 3+ The fluorescence quenching effect of carbon quantum dots from fermented grains enables the quenching of Fe in soy sauce. 3+ Concentration analysis and detection reduce testing costs and achieve energy conservation and environmental protection. Attached Figure Description

[0020] Figure 1 The images show the carbon quantum dots from distiller's grains prepared in Examples 1-4 of this invention under 365nm ultraviolet light irradiation.

[0021] Figure 2 The image shows the XRD pattern of carbon quantum dots from distiller's grains in Example 1 of this invention.

[0022] Figure 3 XPS image of carbon quantum dots from distiller's grains in Example 1 of this invention;

[0023] Figure 4 The image shows the FTIR spectrum of carbon quantum dots from distiller's grains in Example 1 of this invention.

[0024] Figure 5 The images show the UV-Vis absorption spectrum and fluorescence excitation-emission spectrum of the carbon quantum dots from distiller's grains in Example 1 of this invention. The left and right sides of the illustration show the colors of the probe solution under natural light and 365nm wavelength light, respectively.

[0025] Figure 6 The emission spectra of carbon quantum dots from distiller's grains in Example 1 of the present invention under different excitation light are shown.

[0026] Figure 7 The fluorescence response of the carbon quantum dots from the lees in Example 5 of this invention to different metal and non-metal ions;

[0027] Figure 8 The carbon quantum dot fluorescent probe made from distiller's grains in Example 5 of this invention targets Fe. 3+ Fluorescence quenching response diagram;

[0028] Figure 9 The carbon quantum dot fluorescent probe made from distiller's grains in Example 5 of this invention targets Fe. 3+ Linear relationship between concentration and fluorescence quenching response value;

[0029] Figure 10 The fluorescence response of carbon quantum dots from fermented grains loaded on paper strips in Example 1 of this invention to different metal and non-metal ions and different brands of soy sauce;

[0030] Figure 11 The fluorescence response of the carbon quantum dot fluorescent probe made from fermented grains in Example 6 of this invention to different brands of soy sauce is shown. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0033] Example 1

[0034] This embodiment provides a method for preparing carbon quantum dots from distiller's grains, comprising the following steps: after centrifuging the distiller's grains to remove the supernatant, weigh 2.0 g of solids and add 60 mL of deionized water, sonicate for 5 min, then transfer to a 100 mL reaction vessel for heating at 120 °C for 16 h. After heating, allow the reaction vessel to cool to room temperature, centrifuge the obtained solution at 10,000 rpm for 15 min, take the supernatant and filter it using a benchtop aspirator with a filter membrane pore size of 0.22 μm.

[0035] The obtained carbon quantum dot solution from distiller's grains was stored at 4°C for an extended period.

[0036] Example 2

[0037] This embodiment provides a method for preparing carbon quantum dots from distiller's grains, comprising the following steps: after centrifuging the distiller's grains to remove the supernatant, weigh 9.0 g of solids and add 60 mL of deionized water, sonicate for 15 min, then transfer to a 100 mL reaction vessel for heating at 240 °C for 2 h. After heating, allow the reaction vessel to cool to room temperature, centrifuge the obtained solution at 10,000 rpm for 15 min, take the supernatant and filter it using a benchtop aspirator with a filter membrane pore size of 0.22 μm.

[0038] The obtained carbon quantum dot solution from distiller's grains was stored at 4°C for an extended period.

[0039] Example 3

[0040] This embodiment provides a method for preparing carbon quantum dots from distiller's grains, comprising the following steps: After centrifuging the distiller's grains to remove the supernatant, weigh 5.0 g of solids and add 60 mL of deionized water, sonicate for 5 min, then transfer to a 100 mL reaction vessel and heat at 180 °C for 8 h. After heating, allow the reaction vessel to cool to room temperature, centrifuge the obtained solution at 10000 rpm for 15 min, collect the supernatant and filter using a benchtop aspirator with a pore size of 0.22 μm. Dialyze the filtrate using a dialysis bag with a molecular weight cutoff of 500 Da for 24 h, changing the water several times during the process. After dialysis, collect the obtained carbon quantum dots from the distiller's grains.

[0041] The obtained carbon quantum dot solution from distiller's grains was stored at 4°C for an extended period.

[0042] Example 4

[0043] This embodiment provides a method for preparing carbon quantum dots from distiller's grains, comprising the following steps: After centrifuging the distiller's grains to remove the supernatant, weigh 5.0 g of solids and add 60 mL of deionized water, sonicate for 20 min, then transfer to a 100 mL reaction vessel and heat at 220 °C for 6 h. After heating, allow the reaction vessel to cool to room temperature, centrifuge the obtained solution at 10000 rpm for 15 min, collect the supernatant and filter using a benchtop aspirator with a pore size of 0.22 μm. Dialyze the filtrate using a dialysis bag with a molecular weight cutoff of 500 Da for 96 h, changing the water several times during the process. After dialysis, collect the obtained carbon quantum dots from the distiller's grains.

[0044] The obtained carbon quantum dot solution from distiller's grains was stored at 4°C for an extended period.

[0045] like Figure 1 As shown, the carbon quantum dots prepared from distiller's grains in Examples 1-4 all exhibit blue fluorescence under 365nm ultraviolet light irradiation.

[0046] Figure 2 The image shows the XRD pattern of carbon quantum dots from distillers' grains in Example 1 of this invention. The carbon quantum dots from distillers' grains exhibit an amorphous carbon dispersion peak at approximately 2θ = 20°, indicating that the synthesized carbon quantum dots from distillers' grains have an amorphous structure.

[0047] Figure 3 The XPS spectra of the carbon quantum dots from distillery lees in Example 1 of this invention are shown. The omnidirectional XPS spectrum (a) shows three peaks at 284.81 eV, 399.81 eV, and 531.48 eV, attributed to C1s, N1s, and O1s, respectively, indicating the successful introduction of carbon, oxygen, and nitrogen elements into the carbon quantum dots from distillery lees. The high-resolution C1s XPS spectrum can be fitted to three peaks (b) at 284.80 eV, 286.17 eV, and 288.03 eV, corresponding to C–C, CO / C–N, and C=O, respectively. The peak in the N1s spectrum (c) is located at 399.80 eV, attributed to C–N. The O1s spectrum consists of two peaks at 531.34 eV and 532.59 eV, attributed to C=O and CO, respectively (d).

[0048] Figure 4 The image shows the FTIR spectrum of carbon quantum dots from distiller's grains in Example 1 of this invention. CO, -OH / CN, C=C / C=O, O=C=O, CH, and -OH are located at 1120, 1388, 1630, 2366, 2954, and 3426 cm⁻¹, respectively. -1 This is consistent with the results of XPS spectral analysis.

[0049] Figure 5The illustrations show the UV-Vis absorption and fluorescence excitation-emission spectra of carbon quantum dots from distiller's grains in Example 1 of this invention. The left and right sides of the insets show the colors of the probe solution under natural light and 365nm wavelength light, respectively. The UV absorption spectrum of the carbon quantum dots exhibits a distinct shoulder peak at 330nm, corresponding to the n→π* transition in C=O. The excitation spectrum shows a peak at 361nm and an emission peak at 432nm. The insets are photographs of the carbon quantum dot solution from distiller's grains under sunlight and a 365nm UV lamp, respectively. It can be observed that the solution is pale yellow under sunlight and exhibits blue fluorescence under 365nm excitation.

[0050] Figure 6 The images show the emission spectra of carbon quantum dots from distiller's grains in Example 1 of this invention under different excitation wavelengths. When the excitation wavelength is in the range of 350-360 nm, the fluorescence intensity of the carbon quantum dots increases with increasing excitation wavelength, exhibiting a slight redshift. When the excitation wavelength is in the range of 360-380 nm, the fluorescence intensity of the carbon quantum dots decreases with increasing excitation wavelength, exhibiting a significant redshift. This phenomenon indicates that the carbon quantum dots from distiller's grains exhibit excitation wavelength dependence.

[0051] Example 5

[0052] Carbon quantum dots from distiller's grains prepared in Examples 1-4 were used for Fe 3+ The detection.

[0053] (1) Mix 1 mL of distillers' grains carbon quantum dot solution (prepared in Example 3, concentration 0.3 g / mL) with 1 mL of Fe3O4 solution at a concentration of 1000 μg / mL. 3+ Fe 2+ Ag + K + NH4 + Ba 2+ Mg 2+ Cu 2+ and Na + After the aqueous solution was mixed evenly, its fluorescence value was detected at an excitation wavelength of 360 nm in the 380-600 nm band.

[0054] Figure 7 The fluorescence response of carbon quantum dots from distiller's grains to different metal and non-metal ions is shown. F0 represents the fluorescence intensity without carbon quantum dots, and F represents the fluorescence intensity of carbon quantum dots after the addition of metal ions. The fluorescence intensity of the carbon quantum dot solution decreased after the addition of each metal ion, indicating that metal ions can all quench the fluorescence of carbon quantum dots to some extent, but the degree varies significantly. By comparing the changes in fluorescence intensity, it can be seen that Fe... 3+ Compared to other metal ions, carbon quantum dots exhibit a more pronounced ability to quench fluorescence, demonstrating their superior ability to quench Fe. 3+ It has a relatively sensitive selectivity.

[0055] (2) Prepare a 2000 μg / mL ferric chloride solution and dilute it to different concentrations for later use. Use a black 96-well cell culture plate, add 100 μL of distillers' grains carbon quantum dot solution and 100 μL of ferric chloride solution of different concentrations respectively, and detect its fluorescence value at an excitation wavelength of 360 nm in the 380-600 nm band.

[0056] Figure 8 Carbon quantum dot fluorescent probe for distillers' grains against Fe 3+ Fluorescence quenching response diagram: The degree of fluorescence quenching in the distillers' grains carbon quantum dot solution varies with Fe. 3+ The effect increases with increasing concentration, exhibiting a clear dose-dependent effect.

[0057] Figure 9 Carbon quantum dot fluorescent probe for distillers' grains against Fe 3+ Linear relationship between concentration and fluorescence quenching response value; fluorescence quenching degree of distiller's grains carbon quantum dot solution and Fe 3+ The concentration showed a good linear relationship, and in Fe 3+ Fluorescence quenching value of distiller's grains carbon quantum dot solution in concentration range of 400-800 μg / mL and Fe 3+ The concentration conforms to a linear equation in one variable, which facilitates the detection of cases.

[0058] Example 6

[0059] Taking soy sauce as an example, carbon quantum dots from distiller's grains were used to detect Fe in the sample. 3+ Carbon quantum dots from distiller's grains from Example 1 were loaded onto paper strips and subjected to Fe... 3+ Testing.

[0060] Prepare a 1000 μg / mL ferric chloride solution for later use. Mix the ferric chloride solution with Haitian Zero Additive Gold Label Soy Sauce (ZA-LSS), Haitian Iron-Fortified Gold Label Soy Sauce (IF-LSS), Haitian Iron-Fortified Mushroom Dark Soy Sauce (IF-DSS), Chubang Little Mischievous Soy Sauce (LNSS), and Chubang Little Mischievous Iron-Fortified Soy Sauce (IF-LNSS) in equal proportions. Detect the fluorescence value of each mixture at an excitation wavelength of 360 nm within the 380-600 nm band.

[0061] Figure 10This invention, in Example 1, describes the fluorescence response of paper strips loaded with carbon quantum dots from fermented grains to different metal and non-metal ions and different brands of soy sauce. Figure a shows the paper strips immersed in different ion solutions under sunlight; figure b shows the paper strips immersed in carbon quantum dot solution under sunlight after being immersed in different ion solutions; figure c shows the paper strips immersed in carbon quantum dot solution under sunlight after being immersed in different soy sauces; figure d shows the paper strips immersed in different ion solutions at 365 nm; figure e shows the paper strips immersed in carbon quantum dot solution under 365 nm after being immersed in different ion solutions; and figure f shows the paper strips immersed in carbon quantum dot solution under 365 nm after being immersed in different soy sauces. Paper strips not immersed in the carbon quantum dot solution do not fluoresce under ultraviolet light (365 nm), while paper strips immersed in the carbon quantum dot solution show blue fluorescence under ultraviolet light (365 nm). Paper strips impregnated with Fe... 3+ The paper strips showed a clear color change, while other metal ions and non-metal ions still exhibited strong blue fluorescence. Figure 10 e). Figure 10 (a, b) show a comparison under sunlight. In addition, different types of soy sauce were immersed in carbon quantum dot paper strips made from fermented grains. They all showed significant color changes, especially the IF-DSS, which turned deep purple under sunlight. Figure 10 c), and under ultraviolet light (365nm), it causes fluorescence quenching ( Figure 10 f).

[0062] Figure 11 The fluorescence response of the carbon quantum dot fluorescent probe made from fermented grains in Example 6 of this invention to different brands of soy sauce is shown. F0 represents the fluorescence intensity without the addition of carbon quantum dots, and F represents the fluorescence intensity of the carbon quantum dots after the addition of soy sauce. The fluorescence intensity of the carbon quantum dot solution decreased after the addition of different types of soy sauce, indicating that all soy sauces can quench the fluorescence of carbon quantum dots to some extent, but the degree varies significantly. By comparing the changes in fluorescence intensity, it can be seen that IF-DSS has a more significant ability to quench the fluorescence of carbon quantum dots, demonstrating that carbon quantum dots have a more sensitive selectivity for iron-fortified soy sauce.

[0063] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. An application of carbon quantum dots from distiller's grains in iron ion detection, characterized in that, The preparation method of the carbon quantum dots from distiller's grains includes the following steps: The supernatant was removed by centrifugation of the lees to obtain solids. The solids were added to a solvent to form a mixture, which was then sonicated and placed in a reaction vessel for heating. After the reaction, the mixture was filtered to obtain the carbon quantum dots from the lees. The solvent was deionized water, and the lees were rice wine lees. The heating temperature in the reaction vessel was 120-240℃, and the heating time was 2-16 hours.

2. The application according to claim 1, characterized in that, The concentration of the mixture is 3-15 wt%.

3. A test strip for detecting iron ions, characterized in that, The test strip is a cellulose filter paper loaded with carbon quantum dots; the carbon quantum dots are the distillers' grains carbon quantum dots as described in claim 1 or 2.

4. A method for preparing a test strip for detecting iron ions as described in claim 3, characterized in that, The process includes the following steps: cutting cellulose filter paper to the desired size, then soaking it in a solution of carbon quantum dots from distiller's grains, and then removing it to dry at room temperature.

5. The preparation method according to claim 4, characterized in that, The cellulose filter paper is soaked in the distillers' grains carbon quantum dot solution for 4-6 minutes.

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