CN111795938B - Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology - Google Patents
Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology Download PDFInfo
- Publication number
- CN111795938B CN111795938B CN202010541840.4A CN202010541840A CN111795938B CN 111795938 B CN111795938 B CN 111795938B CN 202010541840 A CN202010541840 A CN 202010541840A CN 111795938 B CN111795938 B CN 111795938B
- Authority
- CN
- China
- Prior art keywords
- nano
- cellulose
- aqueous solution
- methylene blue
- concentration
- 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
- 229920001046 Nanocellulose Polymers 0.000 title claims abstract description 41
- 238000001228 spectrum Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 39
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 title claims abstract description 38
- 238000005516 engineering process Methods 0.000 title claims abstract description 9
- 229920002678 cellulose Polymers 0.000 claims abstract description 65
- 239000001913 cellulose Substances 0.000 claims abstract description 65
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229960000907 methylthioninium chloride Drugs 0.000 claims abstract description 63
- 239000007864 aqueous solution Substances 0.000 claims description 46
- 239000000523 sample Substances 0.000 claims description 27
- 238000000870 ultraviolet spectroscopy Methods 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 12
- 238000002835 absorbance Methods 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 238000004611 spectroscopical analysis Methods 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000012496 blank sample Substances 0.000 claims description 2
- 238000010586 diagram Methods 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 abstract description 4
- 238000005342 ion exchange Methods 0.000 abstract description 3
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- 239000003795 chemical substances by application Substances 0.000 abstract 1
- 238000005259 measurement Methods 0.000 abstract 1
- 238000007430 reference method Methods 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000001514 detection method Methods 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 125000002843 carboxylic acid group Chemical group 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 238000004448 titration Methods 0.000 description 4
- OZJPLYNZGCXSJM-UHFFFAOYSA-N 5-valerolactone Chemical compound O=C1CCCCO1 OZJPLYNZGCXSJM-UHFFFAOYSA-N 0.000 description 3
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000005481 NMR spectroscopy Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methyl-cyclopentane Natural products CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002121 nanofiber Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000000954 titration curve Methods 0.000 description 2
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- NASRDENTZCCAPN-UHFFFAOYSA-N OC([Na])=O Chemical compound OC([Na])=O NASRDENTZCCAPN-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000002477 conductometry Methods 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000003988 headspace gas chromatography Methods 0.000 description 1
- 238000007037 hydroformylation reaction Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 150000002500 ions Chemical group 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000008204 material by function Substances 0.000 description 1
- 238000010297 mechanical methods and process Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000010525 oxidative degradation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- KHIWWQKSHDUIBK-UHFFFAOYSA-N periodic acid Chemical compound OI(=O)(=O)=O KHIWWQKSHDUIBK-UHFFFAOYSA-N 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 description 1
- 229960002218 sodium chlorite Drugs 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000002211 ultraviolet spectrum Methods 0.000 description 1
Images
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
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- 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
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
-
- 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
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N2021/3129—Determining multicomponents by multiwavelength light
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The invention discloses a method for measuring carboxyl content of nanocellulose by using a multi-wavelength spectrum technology. Methylene blue is adopted as a color developing agent to form RCOOMB association with carboxyl of the nano-cellulose through ion exchange reaction, and the problem that a spectrum of the methylene blue and a spectrum of the generated association RCOOMB are completely overlapped in a wavelength range of 500-750 nm is solved by combining a multivariate numerical analysis technology. The result shows that compared with the reference method, the method has better measurement precision and accuracy. Therefore, the method is simple, convenient and quick, and is suitable for measuring the content of carboxyl in the nano-cellulose.
Description
Technical Field
The invention belongs to the technical field of analysis and detection, and particularly relates to a method for determining carboxyl content of nanocellulose by using a multi-wavelength spectrum technology.
Background
Nanocelluloses (nanocelluloses) refer to cellulose functional materials with at least one dimension of 1-100 nm in size. Besides the characteristics of wide natural cellulose source, degradability, regeneration and environmental friendliness, the nanocellulose also has the unique advantages of high specific surface area, high strength, high Young modulus, high transparency and the like, so the nanocellulose has wide application prospects in the industries of cosmetics, coatings, biomedicines, energy and electronics and the like. In the preparation process of the nano-cellulose, a chemical method is adopted, such as: TEMPO (2,2,6, 6-tetramethyl piperidine-1-oxygen free radical) -NaBr-NaClO oxidation, persulfate oxidative degradation, periodate hydroformylation modification, sodium chlorite oxidation, carboxymethylation and other treatment processes are combined, hydroxyl on the surface of the nano-cellulose can be converted into carboxylic acid groups, and functional modification based on nano-cellulose materials can be favorably carried out, such as: endowing negative charge characteristic to the nano-cellulose, so that the nano-cellulose suspension is not easy to flocculate and precipitate; improving the dispersibility/compatibility of the nano-cellulose and a non-polar medium; provides an active site for protein/enzyme immobilization. In view of the fact that the carboxyl content of the nano-cellulose is directly related to the performance and application characteristics of products, the establishment of a method for quickly and accurately quantifying the carboxylic acid content is very important for the production, research and application of the nano-cellulose.
At present, conductometry titration based on the titration of strong and weak acid mixtures with a strong base is often used to determine the carboxyl content of cellulose samples. The method comprises the steps of dissolving a cellulose sample by using excessive hydrochloric acid to obtain a colloidal solution of the cellulose sample, back-titrating residual hydrogen ions in the solution by using a NaOH alkali standard solution, indicating the change of a signal in the titration process by using a conductive electrode, drawing a titration curve by using the conductive value to the addition of sodium hydroxide, and further converting the carboxyl content of the cellulose sample by using the difference of the volumes of two break-over points on the titration curve. Compared with an ash method, the method has simpler steps, but has poorer detection accuracy on the sample with low carboxyl content, because the acidified nano cellulose sample is more viscous, the mixing of the acidified nano cellulose sample and a titrant is influenced, the dropping speed of the NaOH alkali standard solution is limited, and although the problem can be solved by dilution, the leap point of the sample with low carboxyl content is difficult to determine.
In addition, some modern instrumental analysis methods (such as ion exchange-headspace gas chromatography, NMR method and the like) are used for reports on relevant researches on cellulose samples, but the chromatographic method needs ion exchange/hydrolysis pretreatment on the samples, so that the requirements of daily rapid detection in industry cannot be met, and the NMR method has high requirements on sample purity and expensive instruments, is not popularized in conventional laboratories and is difficult to popularize.
In the previous reports, the carboxyl group content on the solid fiber was measured by the methylene blue method. The method is based on that after carboxyl on fiber and Methylene Blue (MB) reach adsorption equilibrium, the carboxyl content on the fiber is indirectly and quantitatively detected by measuring the absorbance of the residual methylene blue in filtrate. However, unlike the above samples, nanocellulose is completely water-soluble, its carboxylic acid groups are also water-soluble with methylene blue complex (RCOOMB), and the spectrum of methylene blue itself and the spectrum of carboxylic acid groups on nanocellulose with methylene blue complex are largely overlapping, so it is not possible to determine the component content in an actual mixture by quantitatively detecting the single component with absorption. In the invention, a multi-wavelength spectrometry method based on spectral change of carboxylic acid groups in methylene blue combined nano-cellulose is provided for rapidly determining the carboxyl content of the nano-cellulose, and an effective means is provided for related research and application of determining the carboxyl content of the nano-cellulose.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a method for measuring the carboxyl content of nanocellulose by using a multi-wavelength spectrum technology.
The purpose of the invention is realized by the following technical scheme:
a method for measuring carboxyl content of nano cellulose by using a multi-wavelength spectrum technology comprises the following steps:
(1) scanning the full spectrum of the blank sample with deionized water by using an ultraviolet-visible spectrophotometer (UV-Vis), and correcting an absorbance 0 point;
(2) scanning a full spectrum of a Methylene Blue (MB) aqueous solution by using UV-Vis to obtain a pure spectrum diagram of the methylene blue (I);
(3) scanning the full spectrum of the nano-cellulose aqueous solution by using UV-Vis to obtain a spectrogram of the nano-cellulose aqueous solution;
(4) according to the ratio of MB to nano-cellulose of 20-40 mu mol: 100-200 mg, mixing the MB aqueous solution with the nano-cellulose aqueous solution to obtain a sample to be detected, and scanning by UV-Vis to obtain a spectrogram of a product RCOOMB formed by association of MB and carboxyl on the nano-cellulose;
(5) according to the ratio of MB to nano-cellulose of 20-40 mu mol: 1-5 mg, mixing the MB aqueous solution with the nano-cellulose aqueous solution to obtain a sample to be detected, and scanning by UV-Vis to obtain a binary component mixed spectrogram (IV) of unassociated MB and an association product RCOOMB in the sample to be detected;
wherein the concentration of the MB aqueous solution in the step (2) is the same as the concentration of the MB in the sample to be detected in the steps (4) and (5);
the concentration of the nano-cellulose aqueous solution in the step (3) is the same as that of the nano-cellulose in the sample to be detected in the step (5);
(6) introducing all absorbance data within a certain wavelength range of a pure spectrum (I), a nano-cellulose spectrum (II), a spectrogram of RCOOMB and a mixed spectrogram of binary components (MB and RCOOMB) in the step (5) into a multi-component system multi-wavelength spectrum matrix formula as follows:
wherein A isλiFor all components at λiTotal absorbance at wavelength, Aj λi、kjAnd eλiRespectively represent the component j at the wavelength lambdaiTaking 1,2 as an i term, taking N as an N term, taking 250 as an N term, and taking 2 as an M term; m is the wavelengthThe slope of a spectrum chart of the nano cellulose in the range of 500-750 nm;
then using mathematical solving software Polymath to fit k1And k2A value;
(7) according to the fitted k1The carboxylic acid content in the nanocellulose sample was calculated from the following formula:
wherein, CMBIs the molar concentration of the aqueous MB solution in the step (5); c is the mass concentration of the nano-cellulose, and the unit is mg/L.
Preferably, the concentration of the Methylene Blue (MB) aqueous solution in the step (2) and the concentrations of the Methylene Blue (MB) solutions in the samples to be detected in the steps (4) and (5) are both 10-20 mu mol/L, and the optimal concentration is 15.65 mu mol/L. The concentration of the methylene blue aqueous solution is too large to exceed the detection range of the ultraviolet spectrum, and the sensitivity is too low when the concentration is too small.
Preferably, the concentration of the nano-cellulose aqueous solution in the step (3) and the concentration of the nano-cellulose in the sample to be detected in the step (5) are both 0.5-2.5 mg/L.
Preferably, the solubility of the nano-cellulose in the sample to be detected in the step (4) is 50-100 mg/L.
Preferably, the concentration of the MB aqueous solution in the step (4) is 20-40 mu mol/L, the concentration of the nano-cellulose aqueous solution is 100-200 mg/L, and the volume ratio of the MB aqueous solution to the nano-cellulose aqueous solution is 1: 1.
Preferably, the concentration of the MB aqueous solution in the step (5) is 20-40 mu mol/L, the concentration of the nano-cellulose aqueous solution is 1-5 mg/L, and the volume ratio of the nano-cellulose aqueous solution to the nano-cellulose solution is 1: 1.
Preferably, the wavelength range in the step (6) is 500-750 nm, and the fitting condition satisfies the minimum mean square error principle (c)
Minimum).
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the method is adopted to determine the carboxyl content of the nano-cellulose, and the problem of overlapping of an MB spectrum and a generated associate RCOOMB spectrum is solved by utilizing the ion exchange reaction between the MB and the nano-cellulose carboxyl sodium and the multivariate numerical analysis technology.
(2) The method for determining the carboxyl content of the nano-cellulose widens the limitation of the original methylene blue method only aiming at solid fibers, is suitable for soluble nano-cellulose, and can be extended to the detection of the carboxyl content of other oxidized and carboxylated modified natural high molecular substances by the same principle.
(3) The method for measuring the carboxyl content of the nano-cellulose has the advantages of simple and quick experimental operation and objective and accurate detection result.
Drawings
FIG. 1 is a spectrum of the nanocellulose solution of example 1.
FIG. 2 is a spectrum of MB and RCOOMB in example 1.
FIG. 3 shows the predicted spectrum (calculated by fitting equation 1 in step (6)) and the actual measured spectrum (obtained in step (4)) in example 1.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.
Those who do not specify specific conditions in the examples of the present invention follow conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents and the like which are not indicated for manufacturers are all conventional products which can be obtained by commercial purchase.
The following examples used instrumentation and reagents: model 8453 uv-vis spectrophotometer (Agilent, usa), quartz cuvette (optical path 10mm, Agilent, usa), 20mL headspace vials, magnetic stirrer, precision balance, pipette guns (5mL, 1mL, 100 μ L) at different ranges.
The reagents used were: methylene blue; the cellulose nano-fiber prepared by a mechanical method is marked as CNF; the valerolactone (GVL) pulp and the bleached sulfate pulp are respectively prepared into corresponding nanocelluloses in a laboratory by a mild TEMPO oxidation method, and the nanocelluloses are respectively marked as GTCNF and KTCNF.
Example 1
In this example, the carboxyl content of the nanocellulose prepared by different oxidation processes is determined by the following specific steps:
(1) the full spectrum was scanned with an ultraviolet-visible spectrophotometer (UV-Vis) using deionized water as a blank to correct the absorbance 0 point.
(2) Mixing 5mL of MB aqueous solution with the concentration of 31.3 mu mol/L and 5mL of deionized water, and scanning by UV-Vis to obtain a pure spectrum (r) of methylene blue.
(3) Mixing the nano-cellulose aqueous solution with the concentration of 3mg/L with deionized water with the same volume, and scanning the full spectrum by using UV-Vis to obtain a spectrogram of the nano-cellulose aqueous solution;
(4) uniformly mixing 5mL of MB aqueous solution with the concentration of 31.3 mu mol/L and 5mL of nanocellulose aqueous solution with the concentration of 168mg/L, and scanning by UV-Vis to obtain a spectrogram of RCOOMB which is a product of association of MB and carboxyl on the nanocellulose.
(5) Uniformly mixing 5mL of MB aqueous solution with the concentration of 31.3 mu mol/L and 5mL of nano-cellulose aqueous solution with the concentration of 3mg/L, and scanning by UV-Vis to obtain a binary component mixed spectrogram (r) of residual MB and association product RCOOMB in the solution to be detected.
(6) Introducing absorbance data of the MB spectrum (i), the nano-cellulose spectrum (ii), the RCOOMB (iii) and a mixed spectrum (iv) of binary components (MB and RCOOMB) in the solution to be tested into a multi-wavelength spectrum fitting formula (1):
wherein A isj λi、kjAnd eλiRespectively represent the component j at the wavelength lambdaiTaking 1,2 as the i, 250 as the N and N, and 2 as the M; m is a nanofiber with a wavelength of 500-750 nmSlope of the plain spectrogram III;
then using Polymath mathematical solving software to fit k1And k2The value is obtained.
(7) According to the fitted k1The carboxylic acid content of the nanocellulose sample can be calculated from equation (2). The calculation formula of the carboxyl content in the nano-cellulose sample is as follows:
wherein, CMBIs the molar concentration of the aqueous MB solution in step (5) (concentration when not reacted with nanocellulose); c is the mass concentration of the nano-cellulose, and the unit is mg/L.
To verify the accuracy of the method, the carboxyl content of the nanocellulose prepared from two different raw material pulps by different oxidation processes was measured by the spectroscopy method described herein (performed under the conditions of example 1) and the conventional conductivity titration method, respectively, and the results are shown in table 1. As can be seen from the table, the relative error of the detection results of the two methods on the samples is less than 4.23%, which indicates that the method is suitable for the determination of the carboxyl content in the nano-cellulose sample.
TABLE 1 comparison of methods
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. A method for measuring carboxyl content of nano cellulose by using a multi-wavelength spectrum technology is characterized by comprising the following steps:
(1) scanning the full spectrum of the blank sample with deionized water by an ultraviolet-visible spectrophotometer, and correcting an absorbance 0 point;
(2) scanning the full spectrum of the methylene blue aqueous solution by using UV-Vis to obtain a pure spectrum diagram of methylene blue;
(3) scanning the full spectrum of the nano-cellulose aqueous solution by using UV-Vis to obtain a spectrogram of the nano-cellulose aqueous solution;
(4) according to the ratio of the methylene blue to the nano cellulose of 20-40 mu mol: 100-200 mg, mixing the methylene blue aqueous solution and the nano-cellulose aqueous solution to obtain a sample to be detected, and scanning by UV-Vis to obtain a spectrogram of a product RCOOMB formed by association of methylene blue and carboxyl on the nano-cellulose;
(5) according to the ratio of the methylene blue to the nano cellulose of 20-40 mu mol: 1-5 mg, mixing the methylene blue aqueous solution and the nano cellulose aqueous solution to obtain a sample to be detected, and scanning by UV-Vis to obtain a binary component mixed spectrogram (fourth) of unassociated methylene blue and an association product RCOOMB in the sample to be detected;
wherein, the concentration of the methylene blue aqueous solution in the step (2) is the same as that of the methylene blue in the sample to be detected in the steps (4) and (5); the concentration of the nano-cellulose aqueous solution in the step (3) is the same as that of the nano-cellulose in the sample to be detected in the step (5);
(6) introducing all absorbance data of a pure spectrum (i), a nano-cellulose spectrum (ii), a spectrogram of RCOOMB and a binary component mixed spectrogram (ii) in a certain wavelength range into the following multi-component system multi-wavelength spectrum matrix formula:
wherein A isλiFor all components at λiTotal absorbance at wavelength, Aj λi、kjAnd eλiRespectively represent the component j at the wavelength lambdaiTaking 1,2 as the i, 250 as the N and N, and 2 as the M; m is a spectrum of the nanocellulose with the wavelength of 500-750 nmSlope of (c);
then using mathematical solving software Polymath to fit k1And k2A value;
(7) according to the fitted k1The carboxyl content in the nanocellulose sample was calculated from the following formula:
wherein, CMBThe molar concentration of the methylene blue aqueous solution in the step (5); c is the mass concentration of the nano-cellulose, and the unit is mg/L.
2. The method for measuring carboxyl content of nanocellulose by using the multi-wavelength spectroscopy as claimed in claim 1, wherein the concentration of the methylene blue aqueous solution in the step (2) and the concentration of the methylene blue solution in the samples to be measured in the steps (4) and (5) are both 10-20 μmol/L.
3. The method for measuring carboxyl content of nanocellulose by using the multi-wavelength spectroscopy as claimed in claim 1, wherein the concentration of the nanocellulose aqueous solution in the step (3) and the concentration of nanocellulose in the sample to be measured in the step (5) are both 0.5-2.5 mg/L.
4. The method for measuring carboxyl content of nanocellulose by using the multi-wavelength spectroscopy as claimed in claim 1, wherein the solubility of nanocellulose in the sample to be measured in the step (4) is 50-100 mg/L.
5. The method for measuring carboxyl content of nanocellulose by using the multiple wavelength spectroscopy according to claim 1,2, 3 or 4, wherein said wavelength in step (6) is in the range of 500 to 750 nm.
6. The method for measuring carboxyl content of nanocellulose by using the multi-wavelength spectroscopy as claimed in claim 5, wherein the concentration of the methylene blue aqueous solution in the step (4) is 20-40 μmol/L, the concentration of the nanocellulose aqueous solution is 100-200 mg/L, and the volume ratio of the methylene blue aqueous solution to the nanocellulose aqueous solution is 1: 1.
7. The method for measuring carboxyl content of nano-cellulose by using the multi-wavelength spectroscopy as claimed in claim 5, wherein the concentration of the methylene blue aqueous solution in the step (5) is 20-40 μmol/L, the concentration of the nano-cellulose aqueous solution is 1-5 mg/L, and the volume ratio of the nano-cellulose aqueous solution to the nano-cellulose solution is 1: 1.
8. The method for measuring carboxyl content of nano-cellulose by using the multi-wavelength spectroscopy as claimed in claim 5, wherein the concentration of the methylene blue aqueous solution in the step (2) and the concentration of the methylene blue solution in the samples to be measured in the steps (4) and (5) are both 15.65 μmol/L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010541840.4A CN111795938B (en) | 2020-06-15 | 2020-06-15 | Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010541840.4A CN111795938B (en) | 2020-06-15 | 2020-06-15 | Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111795938A CN111795938A (en) | 2020-10-20 |
| CN111795938B true CN111795938B (en) | 2021-07-20 |
Family
ID=72804726
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010541840.4A Active CN111795938B (en) | 2020-06-15 | 2020-06-15 | Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111795938B (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106198427B (en) * | 2016-07-26 | 2019-01-15 | 华南理工大学 | A kind of five length ultraviolet spectrographic techniques for evaluating metal catalytic reducing agent reducing property |
| CN106644970A (en) * | 2016-09-30 | 2017-05-10 | 华南理工大学 | Three wavelength spectrophotometry method for simultaneously measuring methylene blue and bivalent copper ions in solution by ultraviolet and visible spectrophotometer |
| CN107576738A (en) * | 2017-09-08 | 2018-01-12 | 华南理工大学 | A kind of method of carboxyl-content in headspace gas chromatography detection nano-cellulose |
| CN108760900A (en) * | 2018-03-20 | 2018-11-06 | 华南理工大学 | A kind of headspace gas chromatography measuring sodium carboxymethylcellulose degree of substitution |
| CN108982489B (en) * | 2018-07-05 | 2020-12-29 | 广西大学 | Biomass cellulose-based Cu2+Preparation method and application of detection material |
| CN110954531A (en) * | 2019-12-11 | 2020-04-03 | 东莞理工学院 | Methylene blue colorimetric method for measuring concentration of gamma-PGA in solution |
-
2020
- 2020-06-15 CN CN202010541840.4A patent/CN111795938B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN111795938A (en) | 2020-10-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5440927A (en) | Fiber optic moisture sensor | |
| CN110018141A (en) | A kind of ratio fluorescent analysis method detecting mercury ion | |
| CN111795938B (en) | Method for measuring carboxyl content of nanocellulose by using multi-wavelength spectrum technology | |
| CN104458609B (en) | Method for auxiliary determination of substitution degree of water-soluble food-grade sodium carboxymethylcellulose by microwaves | |
| CN113249115B (en) | Preparation of metal organic framework composite material and application of metal organic framework composite material as ratio type fluorescent probe in detection of hydrogen peroxide and Pi | |
| Klimant et al. | A fiber optical sensor for heavy metal ions based on immobilized xylenol orange | |
| CN113484311A (en) | Method for determining content of calcium sulfate in desulfurization gypsum of coal-fired power plant | |
| CN111363542B (en) | Full-color fluorescent CaF 2 And use of CaF 2 Prepared furfural molecular imprinting ratio fluorescence sensor and preparation method thereof | |
| Kapitonov et al. | Characterization of graphene oxide suspension for fluorescence quenching in DNA-diagnostics | |
| Szejtli et al. | Molecular configuration of amylose and its complexes in aqueous solutions. Part III. Investigation of the DP distribution of helical segments in amylose–iodine complexes | |
| CN104407117B (en) | For the preparation method of the graphene oxide optical biosensor that TNT detects | |
| Li et al. | Selective and accurate detection of nitrate in aquaculture water with surface-enhanced raman scattering (SERS) using gold nanoparticles decorated with β-cyclodextrins | |
| Yang et al. | A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin | |
| CN110646358A (en) | Rapid detection method for beta-cyclodextrin in water sample | |
| CN108408778A (en) | A kind of preparation method and application of molybdenum oxide | |
| CN104819948B (en) | Method for measuring content of dissoluble lignin by utilizing Coomassie brilliant blue G-250 | |
| CN114216885A (en) | Fluorescent detection method for sulfur ions and application thereof | |
| CN113504196A (en) | Method for detecting content of polyvinyl alcohol by spectrophotometry | |
| CN116162277B (en) | Method for rapidly measuring phosphate radical in water | |
| CN108051389B (en) | Method for quantitatively determining content of lignin in wood fiber without separation | |
| CN111504926A (en) | Method for measuring peroxyacetic acid content | |
| CN112525895A (en) | Continuous flow method for measuring content of calcium carbonate in cigarette paper | |
| CN108489921B (en) | Method for quickly detecting cysteine without hydrogen peroxide | |
| CN116120921B (en) | Fluorescent-colorimetric bimodal chloride ion probe based on luminescent gold nanoclusters and preparation method and application thereof | |
| CN1501069A (en) | Preparing and using method for test paper detecting ozone |
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 |