CN113281456A - Quick micro-measuring method for functional groups on surface of biochar - Google Patents
Quick micro-measuring method for functional groups on surface of biochar Download PDFInfo
- Publication number
- CN113281456A CN113281456A CN202110496703.8A CN202110496703A CN113281456A CN 113281456 A CN113281456 A CN 113281456A CN 202110496703 A CN202110496703 A CN 202110496703A CN 113281456 A CN113281456 A CN 113281456A
- Authority
- CN
- China
- Prior art keywords
- biochar
- acid
- titration
- functional groups
- alkali
- 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.)
- Pending
Links
- 125000000524 functional group Chemical group 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000002253 acid Substances 0.000 claims abstract description 51
- 238000004448 titration Methods 0.000 claims abstract description 43
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 34
- 239000003513 alkali Substances 0.000 claims abstract description 23
- 239000000243 solution Substances 0.000 claims abstract description 23
- 238000005303 weighing Methods 0.000 claims abstract description 7
- 239000002585 base Substances 0.000 claims description 14
- 238000005259 measurement Methods 0.000 claims description 7
- 230000008859 change Effects 0.000 claims description 6
- 230000001186 cumulative effect Effects 0.000 claims description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 5
- 239000012498 ultrapure water Substances 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 238000012549 training Methods 0.000 claims description 4
- 238000002479 acid--base titration Methods 0.000 claims description 3
- 230000002378 acidificating effect Effects 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000003610 charcoal Substances 0.000 claims description 3
- 238000010494 dissociation reaction Methods 0.000 claims description 3
- 208000018459 dissociative disease Diseases 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 230000005588 protonation Effects 0.000 claims description 3
- 238000012800 visualization Methods 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 abstract description 14
- 238000002360 preparation method Methods 0.000 abstract description 7
- 238000002474 experimental method Methods 0.000 abstract description 5
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 3
- 238000001139 pH measurement Methods 0.000 abstract description 3
- 239000012086 standard solution Substances 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 238000001514 detection method Methods 0.000 description 3
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 238000004566 IR spectroscopy Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 150000002596 lactones Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- ZPSJGADGUYYRKE-UHFFFAOYSA-N 2H-pyran-2-one Chemical compound O=C1C=CC=CO1 ZPSJGADGUYYRKE-UHFFFAOYSA-N 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000000686 lactone group Chemical group 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000012764 semi-quantitative analysis Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000000954 titration curve Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
-
- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/10—Analysis or design of chemical reactions, syntheses or processes
-
- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/70—Machine learning, data mining or chemometrics
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Theoretical Computer Science (AREA)
- Computing Systems (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- Bioinformatics & Computational Biology (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Biochemistry (AREA)
- Artificial Intelligence (AREA)
- Pathology (AREA)
- Immunology (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Data Mining & Analysis (AREA)
- Databases & Information Systems (AREA)
- Evolutionary Computation (AREA)
- Medical Informatics (AREA)
- Software Systems (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention discloses a quick micro-determination method for functional groups on the surface of biochar, which comprises the following steps: s1, carrying out acid/alkali titration on the surface of the biochar to obtain data; s2, establishing a proton consumption model; s3, compiling a calculation model; and S4, performing fitting calculation on the data. By using an autotitrator to automatically titrate and simultaneously recording the pH value of the solution after each drop of acid/alkali is added, personal error is reduced, and the accuracy of a measuring result is improved. The method has the advantages that 5 standard solutions required by the Boehm titration method are reduced into two solutions, 10 times of titration required by measuring once (recorded by two groups of parallel experiments) by the Boehm titration method is reduced to 2 times of titration, and 24-30 hours for testing is reduced to 1-2 hours, so that the operation is simplified, the measuring time is shortened, the working efficiency is improved, the cost of a used measuring instrument is low, basic operations such as weighing, solution preparation and pH measurement are carried out in the experimental steps, the use of a large instrument is avoided, only hydrochloric acid and sodium hydroxide are used as reagents, and the operability is high.
Description
Technical Field
The invention relates to the technical field of performance characterization, in particular to a quick micro-determination method for functional groups on the surface of biochar.
Background
Currently, Biochar (Biochar) is a class of refractory, stable, highly aromatic, carbon-rich char products produced from the pyrolysis of biomass feedstocks in the absence of oxygen or oxygen. The biochar has a highly carboxylic acid esterified and aromatized structure and rich surface functional groups. The main functional groups on the surface of the biochar comprise oxygen-containing functional groups such as carboxyl, phenolic hydroxyl, carbonyl, lactone, pyrone, anhydride and the like. As an ideal treatment material for pollutants such as organic pollutants, heavy metals, eutrophic salts and the like, the biochar has the surface functional groups capable of providing adsorption sites for adsorbates, and the adsorption performance of the biochar is influenced through p-pi interaction, pi-pi interaction, hydrogen bonds, complexation and the like. Meanwhile, the surface functional groups endow the biochar with stronger pH buffering capacity, and the application of the biochar can relieve the alkalinity and acidity of soil. Therefore, the type and quantity of the functional groups on the surface of the biochar are one of the important evaluation indexes of the biochar product.
At present, a set of complete qualitative and quantitative analysis method for the functional groups on the surface of the biochar material and an accurate standard operating rule are not available at home and abroad. Common methods for measuring the content of the surface functional groups of the biochar in the literature include an infrared spectroscopy (FTIR) method and a Boehm titration method. The infrared spectroscopy utilizes a Fourier transform infrared spectrometer to measure the characteristic absorption peaks of functional groups of the biochar under different wavelengths, and semi-quantitative analysis is carried out by calculating the main absorption peak height of each group, but the method can only obtain the relative content of each group. The Boehm titration method utilizes bases with different strengths to perform neutralization reaction with different surface oxygen-containing functional groups, and calculates the content of the corresponding oxygen-containing functional groups according to the amount of consumed bases, which is the most common method for the chemical analysis of the surface of porous carbon at present.
However, the currently available method for measuring the content of functional groups on the surface of carbonaceous materials by Boehm titration requires at least 1.0g of sample per sample (recorded in two parallel experiments), which is a great burden for preparing mg-grade biochar in a laboratory. Boehm titration uses phenolphthalein as an indicator, and thus there is a large human error in the confirmation of the titration endpoint. At least 10 titrations (in two parallel experiments) are needed to measure the surface functional group content of each sample, and the experimental steps are excessive.
Therefore, the existing determination of the content of the functional group on the surface of the biochar has the problems of excessive carbon consumption, complex measurement process and long time consumption, which are urgently needed to be solved by the technical personnel in the field.
Disclosure of Invention
In view of the above, the invention provides a method for rapidly and micro-measuring functional groups on the surface of biochar, which changes the traditional methods of back titration by a Boehm titration method, manual titration, indication of titration end point by an indicator and the like into automatic titration by using an autotitrator, and simultaneously records the pH value of a solution after each drop of acid/alkali is added, thereby reducing personal errors and improving the accuracy of a measurement result. The method has the advantages that 5 standard solutions required by the Boehm titration method are reduced into two solutions, 10 times of titration required by measuring once (recorded by two groups of parallel experiments) by the Boehm titration method is reduced to 2 times of titration, and 24-30 hours for testing is reduced to 1-2 hours, so that the operation is simplified, the measuring time is shortened, the working efficiency is improved, the cost of a used measuring instrument is low, basic operations such as weighing, solution preparation and pH measurement are carried out in the experimental steps, the use of a large instrument is avoided, only hydrochloric acid and sodium hydroxide are used as reagents, and the operability is high.
In order to achieve the purpose, the invention adopts the following technical scheme:
a quick micro-measuring method for functional groups on the surface of biochar comprises the following steps:
s1, carrying out acid/alkali titration on the surface of the biochar to obtain data;
s2, establishing a proton consumption model;
s3, compiling a calculation model;
and S4, performing fitting calculation on the data.
Preferably, the step S1 specifically includes:
s11, weighing 50.00mg of biochar in a 250mL polytetrafluoroethylene beaker, and adding 50mL of ultrapure water;
s12, arrangement 0.01 mol. L-1NaOH and HCl aqueous solution, and calibrating;
s13, titrating the biochar by using calibrated NaOH and HCl through an autotitrator, and titrating under the inert gas atmosphere;
s14, measuring and recording initial pH by using a pH meter0The pH change after each acid/base addition and the cumulative volume av of acid/base consumed by the biochar.
Preferably, the step S2 specifically includes:
s21, when the surface functional group protonation site on the surface of the biochar is weak monoacid AOH, the dissociation reaction of the proton site is as follows:
AOH＝H++AO-；KH (1)
wherein, surface acid constant
Total surface site concentration ST＝[AOH]+[AO-]In the unit of mol. L-1Then, then
S22, the mass balance equation of acid-base titration is as follows:
wherein, DeltaV is the accumulated volume of acid/alkali consumed by the biochar, so that the acid addition amount is negative, the alkali addition amount is positive, and the unit is mL; c. Ca/bIs the concentration of the acid/alkali solution, and the unit is mol.L-1；V0The total volume of the mixed liquid before titration is in units of mL, Delta [ AO-]The change in concentration of free surface sites before and after titration was expressed in mol. L-1And then:
in the formula (H)+]0Is the initial proton concentration in mol. L-1；
S23, substituting the formula (3) into the acid-base mass balance equation (2):
wherein [ H ]+]＝10-pHSite concentration
The unit is mmol. g-1And m is the charcoal mass in g, and the site concentration is substituted into equation (4):
s24, when the biochar surface contains various types of acid sites, the formula (5) is shown as follows:
wherein i is the number of acidic sites.
Preferably, the step S3 specifically includes:
preferably, the step S4 specifically includes:
s41, importing the data obtained in the step S1, namely the cumulative volume delta V of acid/alkali consumed by the biochar and the pH value of the corresponding solution, and resetting the data dimension;
s42, setting calculation constant parameters;
s43 concentration of acid sites C in the form of a variableiAnd acidity constant pKa,iSetting an initial value of;
s44, setting an iteration number and an acid site variety interval;
s45, training a model to obtain fitting data;
and S46, performing visualization processing on the fitted data.
According to the technical scheme, compared with the prior art, the method for quickly determining the functional groups on the surface of the biochar is provided, the traditional Boehm titration method back titration, manual titration, indicator indication of titration end point and other methods are changed into automatic titration by using an autotitrator, and meanwhile, the pH value of the solution after each drop of acid/alkali is added is recorded, so that personal errors are reduced, and the accuracy of the determination result is improved. The method has the advantages that 5 standard solutions required by the Boehm titration method are reduced into two solutions, 10 times of titration required by measuring once (recorded by two groups of parallel experiments) by the Boehm titration method is reduced to 2 times of titration, and 24-30 hours for testing is reduced to 1-2 hours, so that the operation is simplified, the measuring time is shortened, the working efficiency is improved, the cost of a used measuring instrument is low, basic operations such as weighing, solution preparation and pH measurement are carried out in the experimental steps, the use of a large instrument is avoided, only hydrochloric acid and sodium hydroxide are used as reagents, and the operability is high. The method reduces 1.0g of a sample used by a common surface detection method Boehm titration method each time to 100mg, but the laboratory preparation of the modified biochar is limited by extremely low equipment yield, so that the burden of preparing the biochar in the laboratory is greatly reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic overall flow chart provided by the present invention.
FIG. 2 is a titration curve and a fitting curve of the biological carbon AM400 provided by the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a quick micro-determination method for functional groups on the surface of biochar, which comprises the following steps:
s1, carrying out acid/alkali titration on the surface of the biochar to obtain data;
s2, establishing a proton consumption model;
s3, compiling a calculation model;
and S4, performing fitting calculation on the data.
To further optimize the above technical solution, step S1 specifically includes:
s11, weighing 50.00mg of biochar in a 250mL polytetrafluoroethylene beaker, and adding 50mL of ultrapure water;
s12, arrangement 0.01 mol. L-1NaOH and HCl aqueous solution, and calibrating;
s13, titrating the biochar by using calibrated NaOH and HCl through an autotitrator, and titrating under the inert gas atmosphere;
s14, measuring and recording initial pH by using a pH meter0The pH change after each acid/base addition and the cumulative volume av of acid/base consumed by the biochar.
To further optimize the above technical solution, step S2 specifically includes:
s21, when the surface functional group protonation site on the surface of the biochar is weak monoacid AOH, the dissociation reaction of the proton site is as follows:
AOH＝H++AO-；KH (1)
wherein, surface acid constant
Total surface site concentration
The unit is mol.L-1Then, then
S22, the mass balance equation of acid-base titration is as follows:
ΔV·ca/b＝V0·Δ[AO-] (2)
wherein, DeltaV is the accumulated volume of acid/alkali consumed by the biochar, so that the acid addition amount is negative, the alkali addition amount is positive, and the unit is mL; c. Ca/bIs the concentration of the acid/alkali solution, and the unit is mol.L-1；V0The total volume of the mixed liquid before titration is in units of mL, Delta [ AO-]The change in concentration of free surface sites before and after titration was expressed in mol. L-1And then:
in the formula (H)+]0Is the initial proton concentration in mol. L-1；
S23, substituting the formula (3) into the acid-base mass balance equation (2):
wherein the content of the first and second substances,
site concentration
The unit is mmol. g-1And m is the charcoal mass in g, and the site concentration is substituted into equation (4):
s24, when the biochar surface contains various types of acid sites, the formula (5) is shown as follows:
wherein i is the number of acidic sites.
To further optimize the above technical solution, step S3 specifically includes:
to further optimize the above technical solution, step S4 specifically includes:
s41, importing the data obtained in the step S1, namely the cumulative volume delta V of acid/alkali consumed by the biochar and the pH value of the corresponding solution, and resetting the data dimension;
s42, setting calculation constant parameters;
s43, by variableForm-to-acid site concentration CiAnd acidity constant pKa,iSetting an initial value of;
s44, setting an iteration number and an acid site variety interval;
s45, training a model, and obtaining a smaller error value of the model by adjusting the iteration times and the acid site variety number to obtain fitting data;
and S46, performing visualization processing on the fitted data.
The method reduces 1.0g of a sample used by a common surface detection method Boehm titration method each time to 100mg, but the laboratory preparation of the modified biochar is limited by extremely low equipment yield, so that the burden of preparing the biochar in the laboratory is greatly reduced.
Example 1: a method for measuring the content of functional groups on the surface of biochar is specifically completed according to the following steps:
firstly, 50.00mg of biochar AM400 is accurately weighed into a 250mL polytetrafluoroethylene beaker, and 50mL of ultrapure water is added. The preparation method of the AM400 biochar comprises the following steps: placing corncob powder into corundum crucible boat, and placing into tube furnace at 5 deg.C/min-1The temperature rising speed of the furnace is increased to 400 ℃ for pyrolysis for 2 hours. Obtaining biological carbon AM 400;
(II) use the calibrated 0.01 mol.L-1NaOH and HCl of (1) was passed through an autotitrator at a rate of 0.04 mL/drop at N2The biochar was titrated dropwise under atmosphere. Measuring and recording the initial pH using a pH meter0And the pH after each drop of acid/base addition;
(III) leading the accumulated volume of the consumed acid/alkali and the corresponding pH value into a calculation program, wherein the addition volume of HCl is a negative value, and the addition amount of NaOH is a positive value;
(IV) setting the mass m of the biochar to be 0.05 and the concentration c of the acid/alkali solutiona/bInitial pH 0.010Taking the number of the acid sites i as (1, 6), setting the number of iterations as 10000, and starting the click operation, wherein 7.52 is the number of the acid sites;
(V) obtaining the following fitting results:
TABLE 1
In connection with FIG. 2, it can be seen that the number of acid site species i is assumed when the number of acid site species i is assumed, except that the fitted curve assuming only one surface functional group deviates far from the actual data>After 2, the difference between the fitted curves is not large. The mean square error is the smallest when i is 5, but the difference of the mean square errors of i is 3-5 is within 0.001, so that the fitting accuracy is similar. Looking up a functional group pK obtained by fitting i-3-5aIt can be found that all of the above 3 hypotheses gave pKaA functional group of about 12.3 according to pKaThe phenolic hydroxyl group was judged. pKaFunctional groups around 6.8 should be lactone groups. Residual pKaAll within the range of 1.3-1.7 and the values are very similar according to pKaAnd judged as carboxyl. Therefore, the fitting result of i-3 is considered to be more accurate. The biochar AM400 contains three surface functional groups, namely carboxyl with the content of 12.04mmol/g, lactone with the content of 0.07mmol/g and phenolic hydroxyl with the content of 2.98 mmol/g.
Example 2: a method for measuring the content of functional groups on the surface of biochar is specifically completed according to the following steps:
in order to determine the standard applicable biochar interval, respectively and accurately weighing 30, 40, 50, 60, 70, 80, 90 and 100mg biochar AM400 in a 250mL polytetrafluoroethylene beaker, and adding 50mL of ultrapure water;
(II) use the calibrated 0.01 mol.L-1NaOH and HCl of (1) was passed through an autotitrator at a rate of 0.04 mL/drop at N2The biochar was titrated dropwise under atmosphere. Measuring and recording the initial pH using a pH meter0And the pH after each drop of acid/base addition;
(III) leading the accumulated volume of the consumed acid/alkali and the corresponding pH value into a calculation program, wherein the addition volume of HCl is a negative value, and the addition amount of NaOH is a positive value;
(IV) respectively setting the mass m of the biochar and the concentration c of the acid/alkali solutiona/bWith initial pH0Because the biochar contains three surface functional groups, the number i of the acid sites is (3, 4), the number of iterations is set to 10000, and the operation is started by clicking;
(V) obtaining the following fitting results:
TABLE 2
It can be seen that the results obtained by titrating with biochar of different masses are somewhat different. The reason is that the mean square error is normally distributed when the number of iterations is increased, so the number of iterations should be adjusted after the number of varieties of the biochar surface sites is determined through preliminary fitting, and a calculation model is further trained to correct the fitting result.
The number of acid site species i was fixed to (3, 4), and fitting was performed by adjusting the number of iterations, the results of which are shown in table 3.
TABLE 3
By adjusting the iteration times and training the calculation model, the minimum mean square error can be obtained when the iteration times are about 100000-150000, namely the fitting result is closer to the true value at the moment. The content of phenolic hydroxyl groups obtained by titration when the sample amount of the biochar is 30mg is too high compared with other results because of deviation caused by too low carbon amount, and therefore 40mg can be regarded as the lowest limit of the applicable quality range of the standard biochar. After the sample volume of the biochar is more than 90mg, the content of carboxyl obtained by titration is too low, because the solid-liquid ratio is too high due to 90mg of biochar for a 50mL system, and the surface functional groups of the biochar cannot be completely neutralized with acid and base to cause deviation, therefore 80mg can be regarded as the highest limit of the applicable quality range of the standard biochar. The results of the best fit of the biochar surface functional groups thus obtained are shown in table 4.
TABLE 4
This example is to determine the range of the quality of the biochar suitable for this patent, and the result is (40, 80) mg closed interval, and 50 mg/time is taken as the measurement amount of the biochar surface functional group in this patent in consideration of the micro-demand of the laboratory for the biochar measurement. The biological carbon AM400 is detected to contain three surface functional groups, the content is 55.62mmol/g, pK respectivelya1.1 carboxyl group, content 0.07mmol/g, pKaLactone group (7.1) content, 2.64mmol/g, pKaA phenolic hydroxyl group of 11.4.
The method reduces 1.0g of a sample used by a common surface detection method Boehm titration method each time to 100mg, but the laboratory preparation of the modified biochar is limited by extremely low equipment yield, so that the burden of preparing the biochar in the laboratory is greatly reduced.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. A quick micro-measuring method for functional groups on the surface of biochar is characterized by comprising the following steps:
s1, carrying out acid/alkali titration on the surface of the biochar to obtain data;
s2, establishing a proton consumption model;
s3, compiling a calculation model;
and S4, performing fitting calculation on the data.
2. The method for rapid micro-measurement of biochar surface functional groups according to claim 1, wherein the step S1 specifically comprises:
s11, weighing 50.00mg of biochar in a 250mL polytetrafluoroethylene beaker, and adding 50mL of ultrapure water;
s12, arrangement 0.01 mol. L-1NaOH and HCl aqueous solution, and calibrating;
s13, titrating the biochar by using calibrated NaOH and HCl through an autotitrator, and titrating under the inert gas atmosphere;
s14, measuring and recording initial pH by using a pH meter0The pH change after each acid/base addition and the cumulative volume av of acid/base consumed by the biochar.
3. The method for rapid micro-measurement of biochar surface functional groups according to claim 1, wherein the step S2 specifically comprises:
s21, when the surface functional group protonation site on the surface of the biochar is weak monoacid AOH, the dissociation reaction of the proton site is as follows:
AOH＝H++AO-；KH (1)
wherein, surface acid constant
Total surface site concentration ST＝[AOH]+[AO-]In the unit of mol. L-1Then, then
S22, the mass balance equation of acid-base titration is as follows:
wherein, DeltaV is the accumulated volume of acid/alkali consumed by the biochar, so that the acid addition amount is negative, the alkali addition amount is positive, and the unit is mL; c. Ca/bIs the concentration of the acid/alkali solution, and the unit is mol.L-1；V0The total volume of the mixed liquid before titration is in units of mL, Delta [ AO-]The change in concentration of free surface sites before and after titration was expressed in mol. L-1And then:
in the formula (H)+]0Is the initial proton concentration in mol. L-1；
S23, substituting the formula (3) into the acid-base mass balance equation (2):
wherein [ H ]+]＝10-pHSite concentration
The unit is mmol. g-1And m is the charcoal mass in g, and the site concentration is substituted into equation (4):
s24, when the biochar surface contains various types of acid sites, the formula (5) is shown as follows:
wherein i is the number of acidic sites.
4. The method for rapid micro-measurement of biochar surface functional groups according to claim 1, wherein the step S4 specifically comprises:
s41, importing the data obtained in the step S1, namely the cumulative volume delta V of acid/alkali consumed by the biochar and the pH value of the corresponding solution, and resetting the data dimension;
s42, setting calculation constant parameters;
s43 concentration of acid sites C in the form of a variableiAnd acidity constant pKa,iSetting an initial value of;
s44, setting an iteration number and an acid site variety interval;
s45, training a model to obtain fitting data;
and S46, performing visualization processing on the fitted data.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110496703.8A CN113281456A (en) | 2021-05-07 | 2021-05-07 | Quick micro-measuring method for functional groups on surface of biochar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110496703.8A CN113281456A (en) | 2021-05-07 | 2021-05-07 | Quick micro-measuring method for functional groups on surface of biochar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113281456A true CN113281456A (en) | 2021-08-20 |
Family
ID=77278140
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110496703.8A Pending CN113281456A (en) | 2021-05-07 | 2021-05-07 | Quick micro-measuring method for functional groups on surface of biochar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113281456A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5640330A (en) * | 1995-04-18 | 1997-06-17 | Ibm Corporation | Method for analyzing pH titration data |
| CN104459022A (en) * | 2014-12-24 | 2015-03-25 | 哈尔滨工业大学 | Method for determining content of sodium chloride in hexamethylene 1, 6-disodium dithiosulfate dihydrate |
| CN105067758A (en) * | 2015-08-31 | 2015-11-18 | 哈尔滨工业大学 | Method for measuring content of carbonyl oxygen-containing functional groups on surface of carbon black |
| CN106018673A (en) * | 2016-07-21 | 2016-10-12 | 中国科学院山西煤炭化学研究所 | Quantitative analysis method for surface oxygenic functional groups of graphene materials |
| RU2631618C1 (en) * | 2016-05-31 | 2017-09-25 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Уральский государственный экономический университет" (УрГЭУ) | Method of experimental data receipt for determination of hydrocarbonate ions in mineral waters by potentiometric and acid-base titration methods |
| CN111268878A (en) * | 2020-01-20 | 2020-06-12 | 同济大学 | Method for evaluating methane production by anaerobic biotransformation of excess sludge |
| CN112014345A (en) * | 2020-08-31 | 2020-12-01 | 重庆科技学院 | Kerogen type division method based on FTIR analysis |
-
2021
- 2021-05-07 CN CN202110496703.8A patent/CN113281456A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5640330A (en) * | 1995-04-18 | 1997-06-17 | Ibm Corporation | Method for analyzing pH titration data |
| CN104459022A (en) * | 2014-12-24 | 2015-03-25 | 哈尔滨工业大学 | Method for determining content of sodium chloride in hexamethylene 1, 6-disodium dithiosulfate dihydrate |
| CN105067758A (en) * | 2015-08-31 | 2015-11-18 | 哈尔滨工业大学 | Method for measuring content of carbonyl oxygen-containing functional groups on surface of carbon black |
| RU2631618C1 (en) * | 2016-05-31 | 2017-09-25 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Уральский государственный экономический университет" (УрГЭУ) | Method of experimental data receipt for determination of hydrocarbonate ions in mineral waters by potentiometric and acid-base titration methods |
| CN106018673A (en) * | 2016-07-21 | 2016-10-12 | 中国科学院山西煤炭化学研究所 | Quantitative analysis method for surface oxygenic functional groups of graphene materials |
| CN111268878A (en) * | 2020-01-20 | 2020-06-12 | 同济大学 | Method for evaluating methane production by anaerobic biotransformation of excess sludge |
| CN112014345A (en) * | 2020-08-31 | 2020-12-01 | 重庆科技学院 | Kerogen type division method based on FTIR analysis |
Non-Patent Citations (4)
| Title |
|---|
| YANLING YU等: "Corncob‐to‐xylose residue (CCXR) derived porous biochar as an excellent adsorbent to remove organic dyes from wastewater", 《SURFACE AND INTERFACE ANALYSIS》 * |
| 朱仲良，李通化，鲁准军: "两维pH滴定法同时测定混合极弱酸碱", 《高等学校化学学报》 * |
| 李蜜: "水生植物基生物炭的酸碱性、碱（土）金属浸出性及对 Cu(II)的吸附效应", 《中国优秀博硕士学位论文全文数据库（博士） 工程科技Ⅰ辑》 * |
| 熊志立: "《分析化学》", 31 December 2019, 北京：中国医药科技出版社 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Suzuki et al. | A high-temperature catalytic oxidation method for the determination of dissolved organic carbon in seawater: analysis and improvement | |
| CN114624303B (en) | Electrochemical method for rapidly and quantitatively determining nicotine in electronic cigarette | |
| CN110702639A (en) | Method for measuring furfural content in wool aldehyde | |
| CN108152318B (en) | Method for measuring conversion rate in process of synthesizing p-polyisobutylene phenol by quantitative nuclear magnetic resonance hydrogen spectrum | |
| CN113281456A (en) | Quick micro-measuring method for functional groups on surface of biochar | |
| CN106442342B (en) | A kind of method of sulfur trioxide and sulfuric acid concentration in measurement workplace air | |
| CN110530811B (en) | Analytical detection method for Cd metal element in solid food sample | |
| CN116626087A (en) | Method for quantitatively analyzing allyl sucrose ether content through nuclear magnetic resonance hydrogen spectrum | |
| CN106814144B (en) | Method for determining and analyzing content of dimethyl sulfate in dimethyl fumarate | |
| CN103884668B (en) | A kind of method of the quick total Determination of Vicinal Diketones content of analysis medicated beer semi-finished product | |
| CN105651773A (en) | Method for measuring content of cellulose in tobacco through potassium dichromate oxidation by means of continuous flow analyzer | |
| CN102590317B (en) | PH composite electrode method for measuring content of nitrite ions in solution | |
| CN107677765B (en) | Method for determining organic residue of hydroxylamine salt based on TOC (total organic carbon) derivatization catalytic combustion method | |
| CN112945873A (en) | Method for measuring permanganate index of water | |
| CN109696519B (en) | Method for testing oxidation reduction degree of graphene oxide | |
| CN114184737B (en) | Method for measuring content of hexafluoro-cyclo-triphosphonitrile | |
| CN109521120B (en) | Quantitative determination of DNTF content by GC-AED independent calibration curve method (CIC method) | |
| WO2023206109A1 (en) | Method for determining oxalic acid content of dimethyl oxalate | |
| CN102375018A (en) | Nonaqueous titration method for determining acidity of glyceryl triacetate | |
| CN101231261A (en) | Electro-chemistry method for testing reducing sugar concentration | |
| CN114149365A (en) | Process control method for synthesizing 3-cyano-2, 6-dihydroxy-4-trifluoromethylpyridine triethylamine salt | |
| CN117092052A (en) | Determination method for carboxyl ammoniation modification degree | |
| CN112326577A (en) | Method for determining potassium permanganate consumption in rubber based on visible light spectrophotometry | |
| CN111272684A (en) | Fe in electrolyte2+Method for measuring concentration | |
| CN118225870A (en) | Method for measuring dissolved nitrous oxide in liquid by improving MIMS (MIMS membrane sample injection) mass spectrometer |
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 | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210820 |
|
| RJ01 | Rejection of invention patent application after publication |