CN113514444B - Method for rapidly detecting aging degree of lubricating oil by fluorescence - Google Patents
Method for rapidly detecting aging degree of lubricating oil by fluorescence Download PDFInfo
- Publication number
- CN113514444B CN113514444B CN202110793244.XA CN202110793244A CN113514444B CN 113514444 B CN113514444 B CN 113514444B CN 202110793244 A CN202110793244 A CN 202110793244A CN 113514444 B CN113514444 B CN 113514444B
- Authority
- CN
- China
- Prior art keywords
- carbon quantum
- fluorescence
- lubricating oil
- quantum dot
- fluorescence intensity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000010687 lubricating oil Substances 0.000 title claims abstract description 59
- 230000032683 aging Effects 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims abstract description 20
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 173
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 29
- 239000002253 acid Substances 0.000 claims abstract description 25
- 239000000243 solution Substances 0.000 claims description 127
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 49
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 48
- 238000001514 detection method Methods 0.000 claims description 34
- 230000005284 excitation Effects 0.000 claims description 26
- 238000006243 chemical reaction Methods 0.000 claims description 22
- 229940068918 polyethylene glycol 400 Drugs 0.000 claims description 18
- 235000019441 ethanol Nutrition 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 12
- 238000002189 fluorescence spectrum Methods 0.000 claims description 10
- 230000003247 decreasing effect Effects 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 9
- 230000003287 optical effect Effects 0.000 claims description 8
- 238000009826 distribution Methods 0.000 claims description 7
- 238000000295 emission spectrum Methods 0.000 claims description 7
- 239000011521 glass Substances 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 7
- 239000010453 quartz Substances 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 7
- 125000003277 amino group Chemical group 0.000 claims description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims description 6
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 claims description 5
- 229960002303 citric acid monohydrate Drugs 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 4
- UMVBXBACMIOFDO-UHFFFAOYSA-N [N].[Si] Chemical compound [N].[Si] UMVBXBACMIOFDO-UHFFFAOYSA-N 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 3
- 239000003607 modifier Substances 0.000 claims description 3
- PHQOGHDTIVQXHL-UHFFFAOYSA-N n'-(3-trimethoxysilylpropyl)ethane-1,2-diamine Chemical compound CO[Si](OC)(OC)CCCNCCN PHQOGHDTIVQXHL-UHFFFAOYSA-N 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 2
- 238000007865 diluting Methods 0.000 claims 1
- 238000002156 mixing Methods 0.000 claims 1
- 238000007789 sealing Methods 0.000 claims 1
- 230000008859 change Effects 0.000 abstract description 7
- 238000012544 monitoring process Methods 0.000 abstract description 3
- 239000002086 nanomaterial Substances 0.000 abstract description 2
- 238000010791 quenching Methods 0.000 description 27
- 230000000171 quenching effect Effects 0.000 description 27
- 229910052799 carbon Inorganic materials 0.000 description 24
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 24
- 230000000694 effects Effects 0.000 description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 23
- 238000007792 addition Methods 0.000 description 18
- 150000002500 ions Chemical class 0.000 description 18
- 229910001385 heavy metal Inorganic materials 0.000 description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 239000011651 chromium Substances 0.000 description 14
- 230000035484 reaction time Effects 0.000 description 12
- 239000003921 oil Substances 0.000 description 11
- 238000002474 experimental method Methods 0.000 description 10
- 239000000376 reactant Substances 0.000 description 10
- 239000002904 solvent Substances 0.000 description 10
- 238000001228 spectrum Methods 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 239000002202 Polyethylene glycol Substances 0.000 description 9
- 229920001223 polyethylene glycol Polymers 0.000 description 9
- 230000002378 acidificating effect Effects 0.000 description 8
- 229960004106 citric acid Drugs 0.000 description 8
- 239000007850 fluorescent dye Substances 0.000 description 8
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 8
- 238000006862 quantum yield reaction Methods 0.000 description 8
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- LOUPRKONTZGTKE-WZBLMQSHSA-N Quinine Chemical compound C([C@H]([C@H](C1)C=C)C2)C[N@@]1[C@@H]2[C@H](O)C1=CC=NC2=CC=C(OC)C=C21 LOUPRKONTZGTKE-WZBLMQSHSA-N 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 239000006087 Silane Coupling Agent Substances 0.000 description 5
- LOUPRKONTZGTKE-UHFFFAOYSA-N cinchonine Natural products C1C(C(C2)C=C)CCN2C1C(O)C1=CC=NC2=CC=C(OC)C=C21 LOUPRKONTZGTKE-UHFFFAOYSA-N 0.000 description 5
- 238000002329 infrared spectrum Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 229920002565 Polyethylene Glycol 400 Polymers 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002096 quantum dot Substances 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- 235000001258 Cinchona calisaya Nutrition 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 238000002835 absorbance Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000003763 carbonization Methods 0.000 description 3
- 238000000695 excitation spectrum Methods 0.000 description 3
- 230000005281 excited state Effects 0.000 description 3
- 239000000314 lubricant Substances 0.000 description 3
- 238000004020 luminiscence type Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229960000948 quinine Drugs 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229910000077 silane Inorganic materials 0.000 description 3
- AKYHKWQPZHDOBW-UHFFFAOYSA-N (5-ethenyl-1-azabicyclo[2.2.2]octan-7-yl)-(6-methoxyquinolin-4-yl)methanol Chemical compound OS(O)(=O)=O.C1C(C(C2)C=C)CCN2C1C(O)C1=CC=NC2=CC=C(OC)C=C21 AKYHKWQPZHDOBW-UHFFFAOYSA-N 0.000 description 2
- QGLWBTPVKHMVHM-KTKRTIGZSA-N (z)-octadec-9-en-1-amine Chemical compound CCCCCCCC\C=C/CCCCCCCCN QGLWBTPVKHMVHM-KTKRTIGZSA-N 0.000 description 2
- 239000001576 FEMA 2977 Substances 0.000 description 2
- 229910018540 Si C Inorganic materials 0.000 description 2
- 125000003368 amide group Chemical group 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000000502 dialysis Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000005283 ground state Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 229960003110 quinine sulfate Drugs 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 238000004566 IR spectroscopy Methods 0.000 description 1
- 229910002808 Si–O–Si Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000005917 acylation reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000002199 base oil Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000001506 fluorescence spectroscopy Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- KWLMIXQRALPRBC-UHFFFAOYSA-L hectorite Chemical compound [Li+].[OH-].[OH-].[Na+].[Mg+2].O1[Si]2([O-])O[Si]1([O-])O[Si]([O-])(O1)O[Si]1([O-])O2 KWLMIXQRALPRBC-UHFFFAOYSA-L 0.000 description 1
- 229910000271 hectorite Inorganic materials 0.000 description 1
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 238000004768 lowest unoccupied molecular orbital Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003921 particle size analysis Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000007430 reference method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000029058 respiratory gaseous exchange Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000012916 structural analysis Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 239000010913 used oil Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
- G01N21/643—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" non-biological material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
Landscapes
- Health & Medical Sciences (AREA)
- Immunology (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Optics & Photonics (AREA)
- Molecular Biology (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
A method for rapidly detecting the aging degree of lubricating oil by fluorescence relates to the technical field of application of fluorescent nano materials. Firstly, diluted carbon quantum dot solution, metal ion solution and/or simulated acid are added into simulated lubricating oil, and the fluorescence intensity change is measured in a fluorescence spectrometer, so that the linear relation between the concentration of metal ions and the fluorescence intensity of the simulated acid and the carbon quantum dots is determined. And then adding a carbon quantum dot solution into the lubricating oil to be detected, measuring the fluorescence intensity in a fluorescence spectrometer, and comparing the linear relation to calculate the concentration of metal ions and the acid value in the lubricating oil to be detected, thereby comprehensively judging the aging degree of the lubricating oil. The invention can rapidly diagnose the aging degree of the lubricating oil, has simple, reliable and stable technical operation, and provides theoretical basis and practical significance for rapid monitoring of the lubricating oil.
Description
Technical Field
The invention relates to the technical field of application of fluorescent nano materials, in particular to a method for rapidly detecting the aging degree of lubricating oil by fluorescence.
Background
In recent years, the amount of automobile maintenance has rapidly increased, and the demand for automobile lubricating oil has tended to increase rapidly. During operation of an automotive internal combustion engine, a portion of the lubricating oil may enter the combustion chamber of the engine, forming harmful emissions such as gaseous pollutants or particulates. The consumption of lubricating oil varies with the state of the art of the vehicle and the degree of wear, and in general, the consumption of lubricating oil should be less than 1% (by volume) of the consumption of fuel. However, the lubrication oil consumption of a severely worn engine will be higher. In addition, when the vehicle is in use or scrapped, a huge amount of waste lubricating oil is generated, and although most of the lubricating oil is recycled, a considerable part of the lubricating oil is discarded into water system or soil, so that environmental pollution is caused.
The lubricating oil is gradually aged and deteriorated due to high temperature and oxidation of air during use, and metal powder ground on the friction part, moisture entering the oil due to respiration and other reasons, and impurities invading from the environment pollute the lubricating oil and promote oxidation of the lubricating oil, so that various faults of the machine can be caused. So that the lubricating oil must be replaced after a certain period of use and deterioration.
The carbon quantum dot has the advantages of incomparable optical performance, small size, low toxicity, good biocompatibility and functional modification, low preparation cost, mild reaction conditions and the like, and becomes the first choice of a fluorescent probe, and the fluorescence quenching phenomenon of the carbon quantum dot in lubricating oil can well detect the oxidation degree of the lubricating oil and the content of heavy metal ions (mainly iron and chromium ions) in the lubricating oil, so that the carbon quantum dot plays a good guiding role in reasonable discharge and disposal of waste oil.
Disclosure of Invention
The invention aims to provide a method for rapidly detecting the aging degree of lubricating oil by fluorescence, which can rapidly diagnose the aging degree of the lubricating oil, has simple, reliable and stable technical operation, and provides theoretical basis and practical significance for rapid monitoring of the lubricating oil.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a method for rapidly detecting the aging degree of lubricating oil by fluorescence mainly comprises the following steps:
firstly, adding a diluted carbon quantum dot solution and a metal ion solution with a certain gradient into simulated lubricating oil, and measuring the change of fluorescence intensity in a fluorescence spectrometer so as to determine the linear relation between the concentration of metal ions and the fluorescence intensity of the carbon quantum dots; adding diluted carbon quantum dot solution and a certain gradient amount of simulated acid into simulated lubricating oil, and measuring the change of fluorescence intensity in a fluorescence spectrometer so as to determine the linear relation between the concentration of the simulated acid and the fluorescence intensity of the carbon quantum dot;
secondly, adding a carbon quantum dot solution into the lubricating oil to be detected, measuring the fluorescence intensity in a fluorescence spectrometer, and comparing the linear relation to calculate the concentration of metal ions and the acid value in the lubricating oil to be detected, thereby comprehensively judging the aging degree of the lubricating oil;
finally, setting a lubricant aging replacement threshold, and prompting the replacement of lubricant when the metal ion concentration and the acid value of the lubricant to be tested reach the threshold.
As the preferable technical scheme of the method for rapidly detecting the aging degree of the lubricating oil by fluorescence, fe is selected as metal ions in the detection method 3+ 、Ni 2+ Polyethylene glycol 400 (PEG 400) was used as the simulated lubricating oil and acetic acid was used as the simulated acid.
Compared with the prior art, the invention has the following advantages:
(1) Particle size analysis and HRTEM analysis show that the prepared carbon quantum dots have the size distribution of 1-6 nm and the average particle size of 2.9nm, and the prepared carbon quantum dots have good dispersibility, small size and stable structure. XRD results showed that the prepared CQDs had only one peak around 22 degrees, which proves that it is in an amorphous form. The Fourier infrared transformation spectrum result shows that the prepared CQDs surface contains a silane group and an amino group of KH792, and the modifier is proved to successfully modify the surface of the carbon quantum dot. XPS results show that the element ratio in CQDs is 46.16% C, 23.83% N, 17.37% O, 12.64% Si, and the compound bond is C-C, -NH 2 、N-C＝O、Si-C。
(2) The excitation wavelength of the prepared carbon quantum dot is 370nm, when the excitation wavelength is 300-400 nm, the carbon quantum dot emits bright blue light, the emission peak is 450nm, when the excitation wavelength is increased from 300nm, the intensity of the emission spectrum is increased and then decreased, the position of the emission peak is obviously blue shifted, and red shift occurs again when the emission peak reaches 370 nm.
(3) The fluorescence quantum yield of the prepared carbon quantum dots is calculated to be 46%, the fluorescence yield also changes along with the amount of reactants, the reaction time and the reaction temperature, and after single factor experiments, the reaction condition for preparing the carbon dots is determined to be 30mL of KH792 addition, 30mL of absolute ethyl alcohol addition, 1g of citric acid addition, the reaction temperature is 140 ℃, and the reaction time is 4 hours.
(4) Detection of heavy metal ions (Fe) in polyethylene glycol by using biomass carbon quantum dots as fluorescent probes 3+ 、Mn 2+ 、Cu 2 + 、Cr 3+ 、Ni 2+ ) And an acidic substance, preferably determining the optimal detection conditions. From the regression equation of fluorescence intensity and concentration, correlation coefficient and quenching constant, the results showed that:
(1) CQDs in the detection of Fe 3+ The result is accurate, and the quenching constant is 22687 at 1 mu M-100 mu M (low concentration), which can be used for detecting low concentration Fe 3+ The equation of the relation curve at low concentration is y= -0.22687x+119.52458, and the linear correlation coefficient is R 2 0.96667 the linear curve equation is y= -0.054999x+105.90959 at 200 μm-1000 μm (high concentration) and the linear correlation coefficient is R 2 = 0.9173, the quenching constant is 5499.
(2) CQDs detection of Mn 2+ In the aspect, the detection result is inaccurate at low concentration, the correlation coefficient is only 0.48064, the detection result is more accurate at high concentration, and the quenching constant is 2129, thus the detection method can be used for detecting high-concentration Mn 2+ The equation of the relation curve at high concentration is y= -0.02129x+118.49863, and the linear correlation coefficient is R 2 ＝0.87797。
(3) CQDs in the detection of Cu 2+ The result of the whole detection is inaccurate between 1 mu M and 1mM, the correlation coefficient is only 0.58639, the detection is accurate when the concentration is divided into 1 mu M to 100 mu M (low concentration) and 200 mu M to 1000 mu M (high concentration), at the low concentration, the curve equation is y= -0.3382x+121.28889, and the linear correlation coefficient is R 2 = 0.89111, a quenching constant of 33820, y= -0.01805x+89.16164, a linear correlation coefficient of R at high concentrations 2 = 0.81461, and the quenching constant is 1805, thus, it can be used for detecting low concentration Cu 2+ The fluorescent probe of (2) is slightly inaccurate in detection result at high concentration, has a small quenching constant, and cannot be specifically identified.
(4) CQDs in the detection of Cr 3+ The detection result is inaccurate, the correlation coefficient is only 0.62136, and after the data is piecewise fitted, the obtained linear correlation coefficient is 0.74583 at low concentration and 0.73391 at high concentration, and the correlation is not very good, and can not be used for detecting Cr 3+ However, the quenching constant at low concentration is 22223, and can be used for specific detection of Cr 3+ Means of (3).
(5) CQDs in detection of Ni 2+ The result of the method is accurate in the whole detection result between 1 mu M and 1mM, the correlation coefficient is 0.81438, and the concentration is divided into 1 mu M to 100 mu M (low concentration) and 200 mu M to 1000 mu M (high concentration) for single detection, and the method is more accurate in the detection of the high concentration Ni by using a curve equation of y= -0.218643 x+126.24406, a linear correlation coefficient of 0.84939, a quenching constant of 21864, y= -0.03808+106.34247, a linear correlation coefficient of 0.93665 and a quenching constant of 3808 at the low concentration, so that the method can be used for detecting the high concentration Ni 2+ The effect is generally observed in the case of low concentration detection.
(6) The CQDs has accurate results in the aspect of detecting acetic acid in polyethylene glycol, the linear relation curve equation is y= -0.04914x+121.5713, the linear relation coefficient is 0.97857, the linear relation is good, the quenching constant is 4914, the CQDs can be used as a fluorescent probe for detecting acidic substances in polyethylene glycol, and the detection result is accurate.
(5) Based on the detection of carbon quantum dots in metal ions and acetic acid, the invention provides a method for rapidly detecting the aging degree of lubricating oil by fluorescence, which can rapidly diagnose the aging degree of lubricating oil, has simple, reliable and stable technical operation, and provides theoretical basis and practical significance for rapid monitoring of lubricating oil.
Drawings
Fig. 1 is a graph showing a particle size distribution of carbon quantum dots.
Fig. 2 is an X-ray diffraction pattern of carbon quantum dots.
Fig. 3 is an infrared spectrum of citric acid, silane coupling agent KH792, and carbon quantum dots.
Fig. 4 shows XPS full spectrum (a) of the carbon quantum dot and a high resolution spectrum (b) of the contained element.
Fig. 5 shows the dispersion of the carbon quantum dot solution in various solvents (PEG 400, ethanol, isopropanol, water, oleylamine, n-hexane, respectively) from left to right and its luminescence (b) under irradiation of 370nm excitation wavelength.
Fig. 6 is a fluorescence emission spectrum of a carbon quantum dot solution in different solvents.
Fig. 7 is an excitation spectrum and an emission spectrum of the carbon quantum dot solution.
Fig. 8 is a fluorescence emission spectrum of carbon quantum dots at different excitation wavelengths.
Fig. 9 is a graph of equation (b) fitted to the fluorescence intensity (a) of carbon quantum dots under different pH effects and the fluorescence intensity of carbon quantum dot solution as a function of pH.
Fig. 10 shows fluorescence intensity of carbon quantum dot solutions at different temperatures.
Fig. 11 is a graph of fluorescence intensity of a carbon quantum dot solution versus time.
FIG. 12 is a graph of reaction time versus fluorescence yield.
FIG. 13 is a graph showing the effect of reaction temperature on fluorescence yield.
Fig. 14 is a graph (a) of the relationship between the amount of carbon quantum dots added to polyethylene glycol 400 and fluorescence intensity and a graph (b) of a fitting equation.
Fig. 15 is an infrared spectrum of polyethylene glycol 400 and polyethylene glycol 400 to which carbon quantum dots are added.
FIG. 16 shows the concentration of Fe 3+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M.
FIG. 17 shows Mn at various concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M.
FIG. 18 shows Cu concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M.
FIG. 19 shows different concentrationsCr 3+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M.
FIG. 20 shows Ni concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M.
Fig. 21 is a graph (a) of a fitting equation of acetic acid with different addition amounts to fluorescence intensity of the carbon quantum dots and an influence relation curve (b).
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples.
Example 1
The preparation of the carbon quantum dot solution comprises the following steps:
1g of citric acid monohydrate is weighed and dissolved into 30mL of absolute ethyl alcohol, then 30mL of N-aminoethyl-3-aminopropyl trimethoxy silane KH792 is weighed, the mixture of the citric acid monohydrate and the absolute ethyl alcohol is evenly mixed and then transferred into a polytetrafluoroethylene liner of a 100mL hydrothermal reaction kettle, the mixture is placed into a constant-temperature blast drying box, the reaction temperature is 140 ℃ for 4 hours, the mixture is taken out after the reaction is completed and cooled, and the mixture is diluted 10000 times by the absolute ethyl alcohol and then sealed and stored, so that the ethanol solution of the nitrogen-silicon co-doped carbon quantum dots emitting blue fluorescence is obtained.
In order to facilitate detection of the carbon quantum dots, they were prepared in powder form by the following method:
dialyzing the diluted carbon quantum dot solution with 1000D dialysis bag (anhydrous ethanol as dialysis external solution) for 48h, evaporating the dialyzed solution to about 10mL volume with a rotary evaporator, and drying to obtain carbon quantum dot powder (CQDs) at-30deg.C with a freeze dryer.
Example 2
Characterization and fluorescence properties of prepared carbon quantum dots
1. Particle size distribution
The particle size distribution of the carbon quantum dots was analyzed by a particle size analyzer, and as is clear from the particle size distribution diagram shown in fig. 1, the particle size distribution of the carbon quantum dots was between 1 and 6nm, and the average particle size was 2.9nm.
2. Structural analysis
Phase analysis was performed on carbon quantum dots using XRD, as shown in fig. 2. Only one broad peak with the center of about 22 degrees shows that the prepared carbon quantum dot is in an amorphous state.
The infrared spectrum of a substance is a reflection of its molecular structure, and the absorption peak in the infrared spectrum corresponds to the vibration form of each group in the molecule, and the molecular structure can be estimated from the absorption peak of the functional group. For further analysis, the surface groups of the synthesized carbon quantum dots were characterized by fourier infrared spectroscopy as shown in fig. 3.
Compared with citric acid and a silane coupling agent KH792, the prepared nitrogen-silicon co-doped carbon dots show different absorption peaks. According to analysis of the spectrum, the carbon quantum dot is 1250cm -1 The C=O stretching vibration peak of the amide group appears, which indicates that the carboxyl group in the citric acid and the amino group in the silane coupling agent KH792 undergo an acylation reaction in the reaction process; at 1005cm -1 The peak of (2) belongs to the stretching vibration peak of Si-O-Si; at 3325cm -1 And 735cm -1 The peaks appearing at the positions are CH of the carbon chain skeleton respectively 2 A stretching vibration peak and an antisymmetric deformation peak; 2970cm -1 The peak of (C) is bound-NH 2 Is a stretching vibration peak of (2).
X-ray photoelectron spectroscopy (XPS) is a quantitative spectroscopy technique for determining elemental composition in materials, and chemical and electronic states of the elements contained therein, and is commonly used for the development and preparation of novel materials, analysis of the surfaces of materials, and assisted study of reaction mechanisms. By XPS analysis of the material, not only the chemical composition of the material surface (except H, he) can be detected, but also the chemical valence of the element can be determined. The prepared carbon quantum dot powder was subjected to XPS characterization, and the result was further processed by XPS software as shown in FIG. 4.
Fig. 4a is an XPS full spectrum diagram of a carbon quantum dot, and the full spectrum analysis shows that the surface of the carbon dot contains C, N, O, si elements, and the percentage contents of the elements are respectively: 46.16% C, 23.83% N, 17.37% O, 12.64% Si, indicating that the sample is carbon as the main constituent element. For each element on the basis of full spectrum scanning The elements are scanned in a high resolution mode, and spectrograms of the four elements are subjected to peak separation treatment to obtain different combination forms of the elements (shown in fig. 4 b). The narrow-region spectrum of C1s, by fitting to 1 fitted curve, illustrates the presence of one form of C. The fitted peak at 284.83eV corresponds to a C-C single bond in sp2 form, and forms the skeleton of the carbon quantum dot. The 398.53eV fitted peak in the N1s spectrogram belongs to-NH 2 A key. The peak of 531.68eV in the O1s spectrum belongs to N-c=o, indicating the formation of amide groups. Two fitted peaks were obtained in the Si2p spectrum, the 101.93eV peak belonging to the Si-C bond on the carbon chain.
3. Fluorescence mechanism of carbon quantum dots
The luminescence of the carbon quantum dots originates from the cabreen structure of the zigzag edge. It is well known that the Cabben structure is sensitive to the environment and if the Cabben structure is protonated, fluorescence will quench. In contrast, the amino group is modified to form a defect point, so that an active point which is easily attacked by the original Cabben structure is protected, and the quenching of fluorescence is inhibited. After the excited pi electrons in the quantum dots are transited, the electrons in the first excited state, namely the electrons in the lowest excited state, can emit fluorescence after passing through different excited states in the process of transiting to the ground state, and otherwise, the electrons emit heat in the form of phosphorescence or thermal radiation.
Radovic and bockrah established a structural model with the aim of proving that the edges of graphene sheets are of a cabreen structure with a triplet ground state without hydrogen atoms. The maximum excitation wavelength 370nm of CQDs corresponds to the LUMO orbital of an electron from the corresponding orbital transition to canreen, while the emitted 450nm fluorescence is due to electron-hole recombination. On the other hand, amino radicals generated from amino groups are readily coupled to single electrons on the hectorite orbit of the Cabben structure by the Gomberg-Bachmann reaction. While a single electron on another track can be allowed to come to three destinations: accepting an electron forms a negative charge, losing an electron forms a positive charge or retains the original radical state. No matter how the single electron on the orbit is finally attributed, a defect with energy bandwidth is generated at the active point, and the bandwidth size depends on the influence of grafted amino groups on the conjugated system of the carbon quantum dots.
It is the generation of this defect state that explains that different amino-modified carbon quantum dots have different fluorescence excitation peaks and fluorescence emission peaks. The principle is mainly that electron-hole recombination generating radiation is increased at the defect. The fluorescence luminescence mechanism of the quantum dot in the application is similar to a structural model established by Radovic, and the surface of the quantum dot has different positions or numbers of active sites due to different modifiers in the modification process, so that the quantum dot has different fluorescence excitation peaks and fluorescence emission peaks.
4. Fluorescence properties of carbon Quantum dots
4.1 fluorescent manifestation of carbon Quantum dots in liquid phase
The carbon quantum dot solution prepared by the hydrothermal synthesis method has good dispersibility, good water solubility, and excellent fluorescence performance, and can be dispersed in organic solvents such as n-hexane, methanol, acetone, ethanol and the like. The dispersion effect in various solvents (PEG 400, ethanol, isopropanol, water, oleylamine, n-hexane) is shown in fig. 5a, and it is known that it has good dispersibility in various solvents. FIG. 5b is a photograph of an ultraviolet lamp showing no color under sunlight, and a bright blue fluorescence under excitation of a 370nm fluorescent lamp.
200 mu L of carbon quantum dot solution diluted 10000 times is respectively added into 10mL of solvent (n-hexane, isopropanol, ethanol, water and PEG 400), and the carbon quantum dot solution with the same concentration of different solvents is obtained after the carbon quantum dot solution is uniformly mixed, and the fluorescence intensity of the carbon quantum dots in the different solvents is tested. Fig. 6 is a graph showing fluorescence emission spectra of carbon quantum dot solutions in various solvents, and it can be seen from fig. 6 that the fluorescence intensity of the carbon quantum dots in an organic solvent is greater than that in ultrapure water.
4.2 carbon Quantum dot emission and excitation Spectrum
200 mu L of carbon quantum dot solution diluted 10000 times is added into 10mL of ethanol, and fluorescence measurement is carried out on the mixture by a fluorescence spectrometer to obtain an excitation spectrum and an emission spectrum (figure 7) of the carbon quantum dot solution, wherein the maximum excitation wavelength of the carbon quantum dot solution is 370nm, and the maximum emission wavelength is 450nm as can be seen from figure 7.
FIG. 8 is a graph showing the emission spectra of carbon dot solutions at different excitation wavelengths, wherein the emission peak is 450nm and the half-width is 62.5nm, and the relationship between the fluorescence intensity and the excitation wavelength is: when the excitation wavelength is increased from 300nm, the intensity of the emission spectrum is increased and then decreased, and the position of the emission peak is obviously red-shifted first and blue-shifted again when reaching 370 nm.
4.3 influence of pH variation on fluorescence Properties of carbon Quantum dot solution
Since the pH of the solution has a very significant effect on the fluorescence properties of the carbon quantum dots, we performed different pH effect tests on the prepared silane modified carbon dot solution and analyzed the results. As a result, as shown in fig. 9a, the fluorescence intensity of the carbon dot solution drops sharply under the strong acid (ph=1), which may indicate that the strong acid condition has a quenching effect on the fluorescence of the carbon dot. As the pH is increased from 3 to 11, the fluorescence intensity of the carbon dot solution is gradually increased, and the relationship between the pH and the fluorescence intensity of the carbon dot solution is more intuitively shown in FIG. 9b and is basically linear, the data is linearly fitted, and the correlation coefficient R of a fitting equation is obtained 2 0.95031, the equation can better represent the relationship between the pH and the fluorescence intensity of the carbon dot solution, and also can represent that the linear relationship between the pH and the fluorescence intensity of the carbon dot solution is relatively fit.
4.4 Effect of temperature on fluorescence Properties of carbon Quantum dot solution
In order to examine the change of fluorescence intensity at the temperature of 10 ℃,20 ℃,30 ℃ and 40 ℃ of the solution, the fluorescence intensity of the carbon quantum dot solution is also influenced by temperature through research, and the research is shown in fig. 10. The prepared carbon dot solution is sensitive to temperature, and the fluorescence intensity of the carbon quantum dots is reduced along with the temperature rise, so that the influence of the temperature is considered in a fluorescence experiment, otherwise, the result measured by the experiment is inaccurate. It is worth mentioning that the fluorescence intensity is also restored to almost the original intensity level after the solution is cooled from a higher temperature to a lower temperature.
Meanwhile, a cyclic test is carried out aiming at the influence of temperature on the fluorescence performance of the carbon quantum dots, and the obtained carbon quantum dot has restorability after repeated temperature cycling, which indicates that the structure of the carbon quantum dots is not changed after the temperature change, and the fluorescence intensity is reversible, so that the prepared carbon quantum dot solution has good thermal stability.
4.5 fluorescence stability of carbon Quantum dot solution
The fluorescence intensity of the carbon quantum dots also changes with time. In order to explore the change condition of the fluorescence property of the carbon quantum dot prepared by the method along with time, experiments of the relationship between the fluorescence intensity of the carbon quantum dot solution and time are carried out, the fluorescence intensities of the carbon quantum dot after 0d, 1d, 2d, 3d, 4d, 5d, 6d and 7d are respectively tested, and fig. 11 is a graph of the relationship between the fluorescence intensity of the carbon quantum dot solution and time, and as can be seen from fig. 11, the fluorescence intensity of the carbon dot solution shows a tendency of slowly decreasing when the time is 0-5 d, the fluorescence intensity of the carbon dot solution is basically kept unchanged after 5d, and the fluorescence intensity is about 95% of that of the original 0 d. It can be seen that the fluorescence intensity of the carbon dot solution remains substantially unchanged over time and is substantially stable.
4.6 fluorescence Quantum yield of silane modified carbon Quantum dots
4.6.1 determination of fluorescence yield of carbon Quantum dots
The fluorescence quantum yield of the carbon quantum dot solution is measured by adopting a reference method, 1mol/L sulfuric acid is prepared, a small amount of quinine sulfate is weighed and dissolved in the sulfuric acid, the absorbance is measured to be 0.14, the absorbance of the solution is stabilized below 0.05 by continuously adjusting the quinine sulfate dosage, and the accurate measurement value of the experiment is 0.04. And then the concentration of the carbon quantum dot solution is regulated to ensure that the absorbance is also stabilized below 0.05, and the measured value is 0.04. Sequentially measuring fluorescence intensity of quinine hemisulfate and carbon point solution under 350nm excitation wavelength to obtain quinine hemisulfate solution fluorescence intensity 72 and carbon point solution fluorescence intensity 91, measuring quinine hemisulfate solution fluorescence quantum yield 0.54 under 350nm excitation wavelength, and substituting the above data into formula The fluorescence quantum yield of the silane modified carbon quantum dot solution was calculated to be 46%.
4.6.2 influence of the reaction conditions on the fluorescence yield of the carbon Quantum dot solution
1) Influence of reactant ratio on fluorescence yield of carbon dot solution
First, in order to examine the influence of the ratio of the reactants on the experiment, the reaction temperature of the experiment was designed to 140℃and the reaction time was designed to 4 hours, the 30mL amount of KH792 was kept unchanged, the experimental results were shown in Table 1 by comparing the fluorescence quantum yields of different ratios, with the added amount of citric acid being 1g and the fluorescence quantum yield when ethanol was added being 37% as the highest. In this experiment, when ethanol was added, the fluorescence yield was increased because citric acid was not well dissolved in the silane coupling agent and the reaction of the reactants was not allowed to be sufficiently contacted and reacted completely, and thus, the ethanol was used as a solvent for citric acid and the silane coupling agent were mixed to allow the reactants to be completely contacted.
TABLE 1 influence of different reactant ratios on fluorescence yield
2) Influence of the reaction time on the fluorescence yield of the carbon dot solution
The reaction time affects the extent of the reaction, thereby changing the fluorescence efficiency of the product. 1g of citric acid was dissolved in 30mL of ethanol, mixed with 30mL of KH792, and added to a 100mL polytetrafluoroethylene liner, and the reaction temperature was 140℃and the reaction time was tested at 0.5h, 1h, 2h, 3h, 4h, 6h, and 12h to investigate the effect of the reaction time on fluorescence yield, and the results are shown in FIG. 12. It was found that at 140℃the carbon dot solution produced in a reaction time of 0.5h gave a fluorescence yield of 15%, indicating that the time had less effect on the fluorescence efficiency of the product. After the reaction time is prolonged, the fluorescence efficiency of the product shows a trend of increasing and then decreasing, the peak is 4 hours, and the fluorescence efficiency is 46%, which shows that the reaction degree can also increase along with the extension of the time, and after the reaction time reaches 4 hours, the reaction degree is more complete, and then the reaction time is prolonged, so that the carbon quantum dots have agglomeration phenomenon, the size of the carbon quantum dots is increased, and the fluorescence efficiency is low.
3) Influence of the reaction temperature on the fluorescence yield of the carbon dot solution
The temperature is the most important factor influencing the fluorescence yield of the synthesized carbon quantum dots, and the carbonization degree of reactants is controlled by controlling the reaction temperature, so that the fluorescence yield is influenced. The experiment was performed with the same amounts of reactants as described above for 4 hours at a reaction temperature of 110 c, 120 c, 130 c, 140 c, 150 c, respectively. As shown in FIG. 13, the carbonization degree of the reactant is very low and the fluorescence yield is very low when the temperature is 110 ℃, and the carbonization degree of the reactant is higher and higher with the increase of the temperature, and reaches the maximum to 140 ℃, so that the fluorescence quantum yield is the highest. When the temperature continues to rise, the carbon quantum dot size is increased, and the fluorescence efficiency is reduced.
Example 2
Relationship between fluorescence of carbon quantum dots and metal ions and acid value in simulated oil
1. Selection of the amount of carbon Quantum dots added
Because the components of the oil product in practical application are complex, the base oil polyethylene glycol 400 is used for replacing the simulation experiment. 10mL of polyethylene glycol 400 to 10mL of transparent screw glass bottle were removed by a pipette, 100. Mu.L, 200. Mu.L, 400. Mu.L, 600. Mu.L and 800. Mu.L of the carbon quantum dot solution diluted in example 1 were added thereto, 3mL of the above-mentioned mixed solution was added to a four-way quartz cuvette with an optical path of 10mm, the excitation wavelength was set at 370nm, and the peak intensity of the fluorescence emission spectrum in the sample was measured.
2. Detection of metal ions
In order to simulate metal ions formed after the actual oil product is used, fe is selected according to metal elements in general GCr15 high-carbon chromium bearing steel 3+ 、Cu 2+ 、Cr 3+ 、Mn 2+ 、Ni 2+ The effect of a total of 5 metal ions on the fluorescence of the carbon quantum dots was tested at an excitation wavelength of 370 nm.
Firstly, 1mmol/L Fe is prepared 3+ 、Cu 2+ 、Cr 3+ 、Mn 2+ 、Ni 2+ The metal ion solutions were diluted to a concentration of 1. Mu.M, 5. Mu.M, 10. Mu.M, 20. Mu.M, 50. Mu.M, 60. Mu.M, 70. Mu.M, 80. Mu.M, 90. Mu.M, 100. Mu.M, 200. Mu.M, 400. Mu.M, 600. Mu.M, 800. Mu.M, 1000. Mu.M, respectively, and stored. 10mL of polyethylene glycol 400 is measured and put into a 10mL transparent screw glass bottle, 200 mu L of the carbon quantum dot solution diluted in the embodiment 1 is added into the bottle, the bottle is uniformly shaken, 200 mu L of each metal ion solution with various concentrations is added into the bottle, the bottle is uniformly shaken, and after 2 hours, fluorescence test is carried out. 3mL of the mixed solution is added into a four-way quartz cuvette with an optical path of 10mm, the excitation wavelength is set to be 370nm, the peak intensity of a fluorescence emission spectrum in a sample is measured, and a relation diagram is made according to the relation between the added solutions with the fluorescence intensities of metal ion solutions with different concentrations and the concentrations.
3. Detection of acid value of oil product
The acid value is the amount of potassium hydroxide used to neutralize the acidic substance in the oil, and is expressed as mgKOH/g. Thus, its definition is expressed as the total amount of acidic materials present in the lubricating oil. The acidic materials produced in these oils can cause various levels of corrosion to the machinery. In addition, the acid value of the lubricating oil becomes larger as the lubricating oil is oxidized and deteriorated during storage and use, and the lubricating oil must be replaced when the acid value is larger to a specific value. However, since the acidic substances in the used oil are too complex, acetic acid is used instead of the acidic substances to simulate the experiment.
Weighing 10mL of polyethylene glycol 400, putting into a 10mL transparent screw glass bottle, adding 200 mu L of carbon quantum dot solution into the bottle, shaking uniformly, adding 200 mu L, 400 mu L, 600 mu L, 800 mu L and 1mL of acetic acid, shaking uniformly, waiting for 2 hours, and performing fluorescence test; 3mL of the mixed solution is added into a four-way quartz cuvette with an optical path of 10mm, the excitation wavelength is set to be 370nm, the peak intensity of a fluorescence emission spectrum in a sample is measured, and a relation diagram is made according to the relation between acetic acid with different addition amounts and the fluorescence intensity.
4. Selection of the amount of carbon Quantum dots added
In order to find a proper carbon quantum dot addition amount, so that the carbon quantum dot addition amount has proper fluorescence intensity on a fluorescence spectrometer and can well show the relationship between the fluorescence intensity and the ion concentration in the polyethylene glycol 400, a selection experiment of the carbon quantum dot addition amount is performed.
As can be seen from fig. 14, the addition amount of the carbon quantum dot and the fluorescence intensity thereof in the polyethylene glycol 400 show a good linear relationship, and the correlation coefficient is 0.99253, which indicates that the carbon quantum dot emits light stably therein, and the fluorescence intensity does not lose or decrease at high concentration due to polymerization or other reactions caused by the addition amount, and the fluorescence intensity tends to increase steadily and linearly with the increase of the addition amount. Meanwhile, since the concentration of the metal ions to be detected is low, when the fluorescence intensity is too high, the change rate may be too small by adding the metal ions, and if the addition amount is too low, the fluorescence of the solution at a higher concentration may be completely lost, and the measurement result is inaccurate, so that the addition amount of the carbon quantum dots is 200 mu L.
FIG. 15 is a Fourier infrared transform spectrum of polyethylene glycol 400 and polyethylene glycol with carbon quantum dots added, which is shown in FIG. 15 to be very similar in infrared spectrum, with the only difference that the solution with carbon quantum dots added is 2905cm -1 There is a small peak bulge, which is-NH 2 But the peak is not noticeable because the amount added is too small compared to the solvent. This means that the structure of polyethylene glycol 400 is not destroyed after adding the carbon quantum dots, and its use is not affected.
5. Relationship between fluorescence of carbon quantum dots and various metal ions
According to the Stern-Volmer equation (I 0 /I)-1＝K sv C [84] The resulting fluorescence quenching standard curve was fitted. I 0 : the fluorescence intensity of the carbon quantum dots when no heavy metal ions are added; i: respectively adding the fluorescence intensity of the carbon quantum dots after the heavy metal ions with different concentrations; c: the concentration of the added heavy metal ions; k (K) sv : quenching constant (L/mol).
5.1 different concentrations of Fe 3+ Influence on fluorescence intensity of carbon Quantum dots
FIG. 16 is Fe with different concentration 3+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M. As shown in FIG. 16a, in the polyethylene glycol 400 solution of CQDs, fe is added when 3+ When the concentration is continuously increased, the fluorescence intensity of the whole solution is gradually reduced, and after the linear fitting of the whole data, fe between 1 mu M and 1mM is obtained 3+ The relation curve equation between the carbon quantum dot and the carbon quantum dot solution is y= -0.06582x+111.87475, and the linear correlation coefficient is R 2 The linear relationship is better, but it is observed that when lower concentrations of Fe are added, = 0.91801 3+ The fluorescence intensity of the CQDs is greatly reduced when in solution; when higher concentration of Fe is added 3+ When the solution is added with the carbon quantum dot solution from small concentration to large concentration, the fluorescence intensity of the CQDs is gradually reduced and shows a good linear relationship, thus obtaining Fe between 1 mu M and 100 mu M 3+ The relation curve equation between the carbon quantum dot and the carbon quantum dot solution is y= -0.22687x+119.52458, and the linear correlation coefficient is R 2 = 0.96667; performing linear fitting again between 200 mu M and 1000 mu M, gradually reducing fluorescence intensity when the carbon quantum dot solution is added in the sequence from small concentration to large concentration of heavy metal ions, and obtaining Fe between 200 mu M and 1000 mu M in a good linear relationship 3+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.054990 x+105.90959, and the linear correlation coefficient is R 2 = 0.9173. A quenching constant of 22687 between 1. Mu.M and 100. Mu.M and a quenching constant of 5499 between 200. Mu.M and 1000. Mu.M was calculated according to the Stern-Volmer equation. This result demonstrates that the CQDs can be used as a detector for Fe 3+ The fluorescent probe of the fluorescent probe is accurate in detection, and heavy metal ions can be detected.
5.2 different concentrations of Mn 2+ Influence on fluorescence intensity of carbon Quantum dots
FIG. 17 shows Mn at various concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M. As shown in the figure17, in the polyethylene glycol solution of CQDs, when Mn is added 2+ When the concentration is continuously increased, the fluorescence intensity of the whole solution is gradually reduced, and Mn between 1 mu M and 1mM is obtained after the linear fitting of the whole data 2+ The relation curve equation between the carbon quantum dot and the carbon quantum dot solution is y= -0.02175x+118.62583, and the linear correlation coefficient is R 2 The linear relationship was better, but it was observed that when Mn was added at lower concentrations = 0.83725 2+ The fluorescence intensity of the CQDs is greatly reduced when in solution; when Mn is added in higher concentration 2+ When the CQDs are used in solution, the fluorescence intensity of the CQDs is reduced to a small extent, then piecewise fitting is performed, linear fitting is performed between 1 mu M and 100 mu M (FIG. 17 b), and when the heavy metal ions are added into the carbon quantum dot solution from small to large in concentration, the fluorescence intensity is gradually reduced, but the linear relationship is not good, and Mn between 1 mu M and 100 mu M is obtained 2+ The relation curve equation between the carbon quantum dot and the carbon quantum dot solution is y= -0.077190x+120.77427, and the linear correlation coefficient is R 2 = 0.48064; the linear fitting was again performed between 100. Mu.M and 1000. Mu.M (FIG. 17 c), and when the carbon quantum dot solution was added in the order of the heavy metal ions from small to large, the fluorescence intensity was gradually decreased and a good linear relationship was exhibited, resulting in Mn between 100. Mu.M and 1000. Mu.M 2+ The relation curve equation between the carbon quantum dot and the carbon quantum dot solution is y= -0.02129x+118.49863, and the linear correlation coefficient is R 2 = 0.87797. A quenching constant of 7719 between 1. Mu.M and 100. Mu.M and a quenching constant of 2129 between 200. Mu.M and 1000. Mu.M was calculated according to the Stern-Volmer equation. This result indicates that CQDs cannot be used as a detector for Mn at low concentrations 2+ Can be used for detecting Mn at high concentration 2+ But the detection result is not accurate enough, and the effect can not reach the detection of heavy metal ions in an ideal state.
5.3 different concentrations of Cu 2+ Influence on fluorescence intensity of carbon Quantum dots
FIG. 18 shows Cu concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M. As shown in FIG. 18a, polyethylene glycol solutions in CQDs In the presence of Cu added 2+ When the concentration is continuously increased, the fluorescence intensity of the whole solution is gradually reduced, and after the linear fitting of the whole data, cu between 1 mu M and 1mM is obtained 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.04416x+106.40369, and the linear correlation coefficient is R 2 The linear relationship was poor, = 0.58639, but it was observed that when Cu was added at lower concentrations 2+ The fluorescence intensity of the CQDs is greatly reduced when in solution; when Cu is added in higher concentration 2+ When the solution is used, the fluorescence intensity of CQDs is reduced to a smaller extent, then the piecewise fitting is carried out, and the linear fitting is carried out between 1 mu M and 100 mu M (FIG. 18 b), when the heavy metal ions are added into the carbon quantum dot solution from small to large in concentration, the fluorescence intensity is gradually reduced, and a good linear relationship is presented, so that Cu between 1 mu M and 100 mu M is obtained 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.3382x+121.28889, and the linear correlation coefficient is R 2 = 0.89111; the linear fitting was again performed between 200. Mu.M and 1000. Mu.M (FIG. 18 c), and when the carbon quantum dot solution was added in the order of the heavy metal ions from small to large, the fluorescence intensity was gradually decreased and a good linear relationship was exhibited, resulting in Cu between 200. Mu.M and 1000. Mu.M 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.01805x+89.16164, and the linear correlation coefficient is R 2 = 0.81461. A quenching constant of 33820 between 1. Mu.M and 100. Mu.M and a quenching constant of 1805 between 200. Mu.M and 1000. Mu.M was calculated according to the Stern-Volmer equation. This result demonstrates that the CQDs can be used as a test for Cu 2+ But the detection result is not accurate enough, and the effect can not reach the detection of heavy metal ions in an ideal state.
5.4 different concentrations of Cr 3+ Influence on fluorescence intensity of carbon Quantum dots
FIG. 19 shows the Cr concentration 3+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M. As shown in FIG. 19a, cr is added as it is in a polyethylene glycol 400 solution of CQDs 3+ When the concentration is increased, the fluorescence intensity of the whole solution is gradually reduced, for the solutionAfter linear fitting of the whole data, cr between 1 mu M and 1mM is obtained 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.03459+116.92512, and the linear correlation coefficient is R 2 The linear relationship was poor, = 0.62136, but it was observed that when Cr was added at lower concentrations 3+ The fluorescence intensity of the CQDs is greatly reduced when in solution; when Cr is added in higher concentration 3+ When the solution is used, the fluorescence intensity of CQDs is reduced to a smaller extent, then the piecewise fitting is carried out, and the linear fitting is carried out between 1 mu M and 100 mu M (FIG. 19 b), when the heavy metal ions are added into the carbon quantum dot solution from small to large in concentration, the fluorescence intensity is gradually reduced, and a good linear relationship is presented, so that Cr between 1 mu M and 100 mu M is obtained 3+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.22223x+129.95106, and the linear correlation coefficient is R 2 = 0.74583; the linear fitting was again performed between 200. Mu.M and 1000. Mu.M (FIG. 19 c), and when the carbon quantum dot solution was added in the order of the heavy metal ions from small to large, the fluorescence intensity was gradually decreased and a good linear relationship was exhibited, resulting in Cr between 200. Mu.M and 1000. Mu.M 3+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.01523+103.53699, and the linear correlation coefficient is R 2 = 0.73391. A quenching constant of 22223 between 1. Mu.M and 100. Mu.M and a quenching constant of 1523 between 200. Mu.M and 1000. Mu.M was calculated according to the Stern-Volmer equation. This result indicates that the CQDs cannot be used as a detector for Cr 3+ Is provided.
5.5 different concentrations of Ni 2+ Influence on fluorescence intensity of carbon Quantum dots
FIG. 20 shows Ni concentrations 2+ Fitting curve graph of the effect of fluorescence intensity of carbon quantum dots, (a) 1 mu M-1 mM, (b) 1 mu M-100 mu M, and (c) 200 mu M-1000 mu M. As shown in FIG. 20a, ni is added as it is in the polyethylene glycol solution of CQDs 2+ When the concentration is continuously increased, the fluorescence intensity of the whole solution is gradually reduced, and after the linear fitting of the whole data, ni between 1 mu M and 1mM is obtained 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum solution is y= -0.05546x+118.48074, and the linear correlation coefficient is R 2 ＝0.81438, the linearity is better, but it was observed that when Ni is added at lower concentrations 2+ The fluorescence intensity of the CQDs is greatly reduced when in solution; when Ni is added in higher concentration 2+ When the solution is used, the fluorescence intensity of CQDs is reduced to a smaller extent, so that the data are subjected to piecewise fitting, linear fitting is performed between 1 mu M and 100 mu M (FIG. 20 b), and when the heavy metal ions are added into the carbon quantum dot solution from small to large in concentration, the fluorescence intensity is gradually reduced, and a good linear relationship is shown, so that Ni between 1 mu M and 100 mu M is obtained 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.218648 x+126.24406, and the linear correlation coefficient is R 2 = 0.84939; the linear fitting was again performed between 200. Mu.M and 1000. Mu.M (FIG. 20 c), and when the carbon quantum dot solution was added in the order of the heavy metal ions from small to large, the fluorescence intensity was gradually decreased, and a good linear relationship was exhibited, resulting in Ni between 200. Mu.M and 1000. Mu.M 2+ The relation curve equation between the linear correlation coefficient and the carbon quantum dot solution is y= -0.03808+106.34247, and the linear correlation coefficient is R 2 = 0.93665. A quenching constant of 2186 between 1. Mu.M and 100. Mu.M and a quenching constant of 3808 between 200. Mu.M and 1000. Mu.M was calculated according to the Stern-Volmer equation. This result demonstrates that the CQDs detect Ni as a fluorescent probe at low concentrations 2+ The effect of the method is not accurate enough, and the detection result is accurate at high concentration.
6. Relationship between fluorescence and acid value of carbon quantum dots
The acid number indicates the degree of oxidation of the oil. The acid value is too high, so that the machine is easy to corrode, and the service life of the machine is reduced due to the fact that oil products are deteriorated, and therefore detection of the acid value of the lubricating oil is also very important.
Fig. 21 shows the effect of acetic acid with different addition amounts on the fluorescence intensity of the carbon quantum dots, and as can be seen from fig. 21a, in the polyethylene glycol solution of CQDs, the fluorescence intensity of the whole solution gradually decreases as the amount of acetic acid added increases. It can also be seen from FIG. 21b that the fluorescence peak shifted slightly redly after addition of acetic acid, because the whole solution changed from colorless to yellow after addition of acetic acid, and appeared biased under fluorescence Green. After the whole data are subjected to linear fitting, a relation curve equation between acetic acid and carbon quantum dot solution between 0-1 mL of additive amount is obtained, wherein y= -0.4914x+121.5713, and the linear correlation coefficient is R 2 = 0.97857, the linear relationship is better. The result shows that the prepared CQDs can be used as a fluorescent probe for detecting acidic substances in polyethylene glycol and the detection result is accurate through calculation, wherein the quenching constant is 4914.
Example 3
Based on the research result of the embodiment 2, the method for rapidly detecting the aging degree of the lubricating oil by fluorescence mainly comprises the following steps:
1) Determination of the Linear relationship between the concentration of Metal ions and the fluorescence intensity of carbon Quantum dots
Firstly, 1mmol/L Fe is prepared 3+ 、Ni 2+ And then diluted to a concentration of 1. Mu.M, 5. Mu.M, 10. Mu.M, 20. Mu.M, 50. Mu.M, 60. Mu.M, 70. Mu.M, 80. Mu.M, 90. Mu.M, 100. Mu.M, 200. Mu.M, 400. Mu.M, 600. Mu.M, 800. Mu.M, 1000. Mu.M, respectively, and stored;
weighing 10mL of polyethylene glycol 400, putting into a 10mL transparent screw glass bottle, adding 200 mu L of carbon quantum dot solution (diluted in the embodiment 1 and the same applies below), shaking uniformly, adding 200 mu L of each metal ion solution with various concentrations, shaking uniformly, waiting for 2 hours, and performing fluorescence test;
Adding 3mL of the mixed solution into a four-way quartz cuvette with an optical path of 10mm, setting the excitation wavelength to be 370nm, measuring the peak intensity of a fluorescence emission spectrum in a sample, and making a relation chart according to the relation between metal ion solutions with different concentrations and the fluorescence intensity;
2) Determination of the linear relationship between the concentration of the simulated acid and the fluorescence intensity of the carbon quantum dots
Weighing 10mL of polyethylene glycol 400, putting into a 10mL transparent screw glass bottle, adding 200 mu L of carbon quantum dot solution into the bottle, shaking uniformly, adding 200 mu L, 400 mu L, 600 mu L, 800 mu L and 1mL of acetic acid, shaking uniformly, waiting for 2 hours, and performing fluorescence test;
adding 3mL of the mixed solution into a four-way quartz cuvette with an optical path of 10mm, setting the excitation wavelength to be 370nm, measuring the peak intensity of a fluorescence emission spectrum in a sample, and making a relation chart according to the relation between acetic acid with different addition amounts and the fluorescence intensity;
3) Detection of used lubricating oil
Adding 200 mu L of carbon quantum dot solution into 10mL of used lubricating oil to be detected, measuring fluorescence intensity in a fluorescence spectrometer, and calculating the concentration of metal ions and the acid value in the lubricating oil to be detected by comparing the linear relation obtained in the step 2) and the step 3), thereby comprehensively judging the aging degree of the lubricating oil;
4) Replacement prompt
And setting an aging replacement threshold value of the lubricating oil, and prompting the replacement of the lubricating oil when the metal ion concentration and the acid value of the lubricating oil to be detected reach the threshold value.
The foregoing is merely illustrative and explanatory of the principles of the invention, as various modifications and additions may be made to the specific embodiments described, or similar thereto, by those skilled in the art, without departing from the principles of the invention or beyond the scope of the appended claims.
Claims (1)
1. A method for rapidly detecting the aging degree of lubricating oil by fluorescence is characterized by comprising the following main steps:
step 1, preparation of carbon quantum dot solution
Weighing 1g of citric acid monohydrate, dissolving the citric acid monohydrate into 30 mL absolute ethyl alcohol, weighing 30 mL N-aminoethyl-3-aminopropyl trimethoxy silane KH792, uniformly mixing the citric acid monohydrate and the N-aminoethyl-3-aminopropyl trimethoxy silane KH792, transferring the mixture into a polytetrafluoroethylene liner of a 100 mL hydrothermal reaction kettle, placing the mixture into a constant-temperature blast drying box, reacting at 140 ℃ for 4 h, taking the mixture out after the reaction is completed and cooled, diluting the mixture with 10000 times of absolute ethyl alcohol, and sealing and preserving the diluted mixture to obtain an ethanol solution of nitrogen-silicon co-doped carbon quantum dots emitting blue fluorescence;
The prepared carbon quantum dots have the size distribution of 1-6 nm, the average particle size of 2.9 nm, good dispersibility, small size and stable structure; the prepared CQDs surface contains a silane group and an amino group of KH792, which indicates that the modifier successfully modifies and modifies the surface of the carbon quantum dot; the excitation wavelength of the prepared carbon quantum dot is 370nm, when the excitation wavelength is 300-400 nm, the carbon quantum dot emits bright blue light, the emission peak is 450nm, when the excitation wavelength is increased from 300nm, the intensity of the emission spectrum is increased firstly and then decreased, the position of the emission peak is obviously blue shifted firstly, and red shift occurs again when the emission peak reaches 370 nm;
step 2, determining the linear relation between the concentration of metal ions and the fluorescence intensity of the carbon quantum dots
Firstly, 1 mmol/L Fe is prepared 3+ 、Ni 2+ And then diluted to a concentration of 1. Mu.M, 5. Mu.M, 10. Mu.M, 20. Mu.M, 50. Mu.M, 60. Mu.M, 70. Mu.M, 80. Mu.M, 90. Mu.M, 100. Mu.M, 200. Mu.M, 400. Mu.M, 600. Mu.M, 800. Mu.M, 1000. Mu.M, respectively, and stored;
weighing 10 mL of polyethylene glycol 400, putting into a 10 mL transparent screw glass bottle, adding 200 mu L of the carbon quantum dot solution diluted by ethanol in the step 1, shaking uniformly, adding 200 mu L of each metal ion solution with various concentrations, shaking uniformly, waiting for 2 h, and performing fluorescence test;
Adding the mixed solution of 3 mL into a four-way quartz cuvette with an optical path of 10 mm, setting excitation wavelength to be 370 nm, measuring peak intensity of fluorescence emission spectrum in a sample, and making a relation chart according to the relation between metal ion solutions with different concentrations and fluorescence intensity;
step 3, determining the linear relation between the simulated acid concentration and the fluorescence intensity of the carbon quantum dots
Weighing 10 mL of polyethylene glycol 400, putting into a 10 mL transparent screw glass bottle, adding 200 mu L of the carbon quantum dot solution diluted by ethanol in the step 1, shaking uniformly, adding 200 mu L, 400 mu L, 600 mu L, 800 mu L and 1 mL of acetic acid, shaking uniformly, waiting for 2 h, and performing fluorescence test;
adding the mixed solution of 3 mL into a four-way quartz cuvette with an optical path of 10 mm, setting excitation wavelength to be 370 nm, measuring peak intensity of fluorescence emission spectrum in a sample, and making a relation chart according to the relation between acetic acid with different addition amounts and fluorescence intensity;
step 4, detection of used lubricating oil
Adding 200 mu L of the carbon quantum dot solution diluted by ethanol in the step 1 into the used lubricating oil to be detected of 10 mL, measuring the fluorescence intensity in a fluorescence spectrometer, and calculating the concentration of metal ions and the acid value in the lubricating oil to be detected by comparing the linear relation obtained in the step 2 and the step 3 so as to comprehensively judge the aging degree of the lubricating oil;
Step 5, replacement prompt
And setting an aging replacement threshold value of the lubricating oil, and prompting the replacement of the lubricating oil when the metal ion concentration and the acid value of the lubricating oil to be detected reach the threshold value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110793244.XA CN113514444B (en) | 2021-07-14 | 2021-07-14 | Method for rapidly detecting aging degree of lubricating oil by fluorescence |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110793244.XA CN113514444B (en) | 2021-07-14 | 2021-07-14 | Method for rapidly detecting aging degree of lubricating oil by fluorescence |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113514444A CN113514444A (en) | 2021-10-19 |
| CN113514444B true CN113514444B (en) | 2024-02-09 |
Family
ID=78067019
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110793244.XA Active CN113514444B (en) | 2021-07-14 | 2021-07-14 | Method for rapidly detecting aging degree of lubricating oil by fluorescence |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113514444B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114609107A (en) * | 2022-03-14 | 2022-06-10 | 吉林大学 | Fluorescent probe based on red light carbon quantum dots and application of fluorescent probe in detection of ethanol concentration in ethanol-water system |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104560037A (en) * | 2015-01-15 | 2015-04-29 | 复旦大学 | Method of preparing carbon quantum dots with high quantum yield in oil phase |
| CN106814053A (en) * | 2017-01-17 | 2017-06-09 | 陕西师范大学 | The quantitative approach of oxide in trace quantities since impurity in FVC68D refrigerator oils |
| CN109307665A (en) * | 2018-10-25 | 2019-02-05 | 同济大学 | It is a kind of to detect Fe using fluorescent carbon quantum dot3+Method |
| CN110426376A (en) * | 2019-03-06 | 2019-11-08 | 长春工业大学 | A kind of preparation and application of the fluorescence nano sensor of auto continuously variable transmission wear condition detection function |
| CN112724967A (en) * | 2021-01-08 | 2021-04-30 | 中南林业科技大学 | Phosphoric acid skeleton functionalized fluorescent carbon dot and preparation method and application thereof |
-
2021
- 2021-07-14 CN CN202110793244.XA patent/CN113514444B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104560037A (en) * | 2015-01-15 | 2015-04-29 | 复旦大学 | Method of preparing carbon quantum dots with high quantum yield in oil phase |
| CN106814053A (en) * | 2017-01-17 | 2017-06-09 | 陕西师范大学 | The quantitative approach of oxide in trace quantities since impurity in FVC68D refrigerator oils |
| CN109307665A (en) * | 2018-10-25 | 2019-02-05 | 同济大学 | It is a kind of to detect Fe using fluorescent carbon quantum dot3+Method |
| CN110426376A (en) * | 2019-03-06 | 2019-11-08 | 长春工业大学 | A kind of preparation and application of the fluorescence nano sensor of auto continuously variable transmission wear condition detection function |
| CN112724967A (en) * | 2021-01-08 | 2021-04-30 | 中南林业科技大学 | Phosphoric acid skeleton functionalized fluorescent carbon dot and preparation method and application thereof |
Non-Patent Citations (1)
| Title |
|---|
| CVTF状态监测系统开发及在CVT故障诊断中的应用;韩玲等;润滑与密封;第45卷(第10期);92-98 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113514444A (en) | 2021-10-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Li et al. | Dually emitting carbon dots as fluorescent probes for ratiometric fluorescent sensing of pH values, mercury (II), chloride and Cr (VI) via different mechanisms | |
| Cai et al. | Preparation, characterization and evaluation of water-soluble L-cysteine-capped-CdS nanoparticles as fluorescence probe for detection of Hg (II) in aqueous solution | |
| Jayaweera et al. | Fluorescent N/Al Co-doped carbon dots from cellulose biomass for sensitive detection of manganese (VII) | |
| Huang et al. | Preparation of graphene oxide and polymer-like quantum dots and their one-and two-photon induced fluorescence properties | |
| CN109307665B (en) | Method for detecting Fe by using fluorescent carbon quantum dots3+Method (2) | |
| Zhang et al. | Fluorescent method for the determination of sulfide anion with ZnS: Mn quantum dots | |
| Diao et al. | Fluorescence-detecting cationic surfactants using luminescent CdTe quantum dots as probes | |
| Omer et al. | Improvement of selectivity via the surface modification of carbon nanodots towards the quantitative detection of mercury ions | |
| Tall et al. | Green emitting N, P-doped carbon dots as efficient fluorescent nanoprobes for determination of Cr (VI) in water and soil samples | |
| CN113514444B (en) | Method for rapidly detecting aging degree of lubricating oil by fluorescence | |
| CN113340860B (en) | Manganese-doped carbon dot and Mn-CDs solution for detecting Fe & lt 3+ & gt, test paper, preparation method of test paper and detection method of test paper | |
| Adinarayana et al. | Facile green synthesis of silicon nanoparticles from Equisetum arvense for fluorescence based detection of Fe (III) ions | |
| CN110591692A (en) | Upconversion nano particle modified by nitroso tetrafluoroborate, nano probe, preparation method of nano probe and detection method of sulfur-containing compound | |
| Feng et al. | A novel biosensor for copper (II) ions based on turn-on resonance light scattering of ssDNA templated silver nanoclusters | |
| Kainth et al. | Deciphering the interaction of solvents with dual emissive carbon dots: A photoluminescence study and its response for different metal ions | |
| Muthurasu et al. | Tuning optical properties of nitrogen-doped carbon dots through fluorescence resonance energy transfer using Rhodamine B for the ratiometric sensing of mercury ions | |
| Chu et al. | The parallel fluorescence determination of iron (III), terbium (III) and europium (III) ions using the coal-derived carbon dot | |
| CN116534812A (en) | Fluorescent graphite phase carbon nitride quantum dot, and preparation method and application thereof | |
| CN114854405A (en) | Multi-emission fluorescent carbon dot and preparation method and application thereof | |
| Wen et al. | Synthesis optimization of rich-urea carbon-dots and application in the determination of H 2 S in rich-and barren-liquids of desulphurizing solutions | |
| Parani et al. | Mn-doped ZnSe quantum dots as fluorimetric mercury sensor | |
| Yu et al. | Near‐Infrared Fluorimetric Determination of Copper (II) Ions Using CdHgTe Nanorods as Probe | |
| Cheng et al. | A highly efficient, rapid, room temperature synthesis method for coal-based water-soluble fluorescent carbon dots and its use in Fe3+ ion detection | |
| CN116376545B (en) | Preparation of N, S co-doped red light carbon dot material and application of N, S co-doped red light carbon dot material in visual detection of heavy metal ions | |
| CN114441493B (en) | Method for detecting chromium ions by using chitosan composite quantum dot fluorescence |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |