CN101852726B - Method for detecting activity of metakaolin by using spectrophotometer - Google Patents

Abstract

A method for detecting the activity of metakaolin by using a spectrophotometer relates to a metakaolin. A method for detecting metakaolin activity by using a spectrophotometer is provided, which is simple and convenient in operation, fast in determination and reliable in result. Pour the sample into a container, add hydrochloric acid, heat the reaction, add water to the filtrate to make up the volume; put the aluminum sheet in the container, soak and dissolve the surface oxide layer with hydrochloric acid, pour off the hydrochloric acid solution, put the aluminum sheet in the container, add Wang Water, heat to dissolve, transfer into the volumetric flask, dilute with water, pipette into the volumetric flask, dilute with water, take 1μg/mL aluminum standard solution in the volumetric flask, add ascorbic acid solution, chromazurin-S ethanol solution, six sub- Methyltetramine solution, add water to constant volume, then move it into an absorption dish, measure the absorbance at a spectrophotometer wavelength of 545nm, and find the slope of the aluminum working standard curve; measure the aluminum content in the pickling solution, and then calculate the active alumina in metakaolin content.

Description

A method for detecting the activity of metakaolin by using a spectrophotometer

technical field

The invention relates to metakaolin, in particular to a method for detecting the activity of metakaolin by using a spectrophotometer.

Background technique

Metakaolin is a metastable substance with certain chemical activity obtained after calcining kaolin at an appropriate temperature. The atomic arrangement in metakaolin is irregular, showing a thermodynamic metastable state, and has high pozzolanic activity. Therefore, metakaolin is a highly active artificial pozzolanic material. Due to its unique mineral properties, metakaolin can be used not only as a new type of mineral admixture, but also in the research and application of new cementitious materials.

Metakaolin can react with cement hydration product Ca(OH) ₂ to form gelling substances such as calcium aluminate hydrate and CSH gel. It has high hydration activity and can be used as a concrete mineral admixture. It has the ability to improve hardening Improve the workability and durability of concrete, and reduce the self-shrinkage of cement stone. Metakaolin can also be used to prepare geopolymeric cementitious materials. The geopolymeric cementitious material is formed by metakaolin under the combined action of alkaline activators and hardening accelerators and other external materials. It not only has low production energy consumption and less pollution, but also can utilize a large amount of industrial waste residues. It is a promising development prospect. Green building materials meet the requirements of low-carbon economy and sustainable development.

Only highly active metakaolin can be widely used. Therefore, activity is the primary detection index of metakaolin. Experience has pointed out that the calcination temperature of metakaolin with high activity will be different for different sources of kaolin. Therefore, the activity of metakaolin needs to be tested.

At present, the methods for evaluating the activity of metakaolin include: X-ray diffraction analysis, thermogravimetric analysis, scanning calorimetry analysis, alkali absorption method, calcium absorption method, compression strength measurement method, strength comparison method and activated alumina content method, etc.

Related literature (Torres Sánchez R M, Basaldella E I, Marco J F. The effect of thermal and mechanical treatment on kaolinite: Characterization by XPS and IEP measurements[J]. Journal of Colloid and Interface Science, 1999, 215: 339-344.; Cao Deguang, Chen Yilan, Ou Shaoquan. Alkali gelation of burnt clay[J]. China Non-Metallic Mineral Industry Guide, 2000, 21-22(2): 28.; Kakali G, Perraki T, Tsivilis S, et al Thermal Treatment of kaolin: the effect of mineralology on the pozzolanic activity. [J]. Applied Clay Science, 2001, 20: 73-81.) Kaolin was calcined according to different calcination systems, and the calcined metakaolin was analyzed by X-ray diffraction, thermal Gravity analysis, scanning calorimetry analysis, etc., so as to indirectly judge the activity of the calcined metakaolin. However, X-ray diffraction analysis, thermogravimetric analysis, scanning calorimetry and other instrumental analysis methods directly analyze metakaolin, emphatically describe the change rule of the crystal structure of kaolin under a certain calcination system, and cannot directly explain the activity of metakaolin obtained. size.

French professor Davidovits believes (Davidovits J.Geopolymer Chemistry and Properties[J].Proceedings of the First European Conference on Soft Mineralogy, 1988, (1): 429-441.) The formation process of soil polymer is by dissolution, monomer reconstruction Composed of three stages of polycondensation, the restructured monomer undergoes a polycondensation reaction similar to the formation of organic polymers, and the alkali metal ions play a role in balancing the electricity price in the final product. Due to the different calcination temperature and holding time of metakaolin, the number and structure of its hydroxyl groups are different, so the dissolution rate of metakaolin in alkali solution is different, resulting in different absorption of alkali. Therefore, the alkali absorption method (Guo Wenying, Wu Guolin, Wen Ziyun, etc. Research on the activity evaluation method of metakaolin [J]. Journal of Wuhan University of Technology, 2006, (03): 76-79.) can distinguish whether metakaolin has activity . However, experimental studies have shown that the law of activity of metakaolin with better activity is not consistent with the law of 3D strength of soil polymer.

The calcium absorption method is mainly based on the action of active silica and alumina in the material with lime to generate hydrous calcium silicate and hydrous calcium aluminate. Therefore, within a certain period of time, the amount of lime in the lime solution absorbed by the material can indicate its activity. However, for the test system of metakaolin excited by sodium silicate solution, due to the lack of calcium, this method is not suitable for evaluating the activity of metakaolin in such systems.

Metakaolin is an amorphous aluminosilicate in an unstable state. It is a substance with free energy. According to the contact hardening theory of ΓУXOBCКИЙ (ΓJIУXOBCКИЙBД, PУHOBAPΦ, MACУHOBCE. Contact hardening cementitious materials and composite materials [M] Translated by Pu Xincheng. Chongqing: Chongqing University Press, 2004.), metakaolin should have a tendency to polycondensate, so compression methods can be used to make it produce strength. The research results of Guo Wenying and others also show that this method cannot quantitatively describe the size of the activity .

The strength comparison method refers to the direct use of sodium silicate to stimulate metakaolin to prepare geopolymeric cementitious materials, and to measure the parameters such as compressive strength or flexural strength after curing to a certain age to evaluate the activity of metakaolin. This method is the most effective and intuitive method to evaluate the activity of metakaolin, but it usually takes 3 days or 7 days to get the result, which is too long and not suitable for production.

The alumina in calcined kaolin can be divided into two types: one type has good activity in acid, such as γ-Al ₂ O ₃ , which is generally called active aluminum; the other type has poor activity in acid, such as α -Al ₂ O ₃ , called inert aluminum. In fact, activated alumina is a collection of all forms of aluminum in kaolin that can react with acids, and it is converted into γ-Al ₂ O ₃ to appear. In the acid leaching reaction of kaolin, inert aluminum basically does not contribute to the reaction.

Xu Chao et al. (Xu Chao, Zhang Xingfa, Han Xiaozhao, Xu Mincai. Determination of active alumina in kaolin [J]. Nonmetallic Minerals, 1998, 21(5): 13-14) made acid leaching of metakaolin under certain experimental conditions After treatment, use the EDTA volumetric method to analyze and determine the content of activated alumina in it, so as to quantitatively compare the activity of metakaolin. The determination method can be summarized as follows: metakaolin is leached with hydrochloric acid to activate alumina under heating conditions. Add excess EDTA to complex with aluminum plasma. When PH = 6, titrate the excess EDTA with zinc acetate solution, then add sodium fluoride, so that the aluminum ions complexed by EDTA become fluoride-aluminum complex ions, and release etc. amount of EDTA, and then titrate the released EDTA with zinc acetate solution to calculate the content of activated alumina. For iron-stained kaolin, the pickling solution contains more iron ions. Since both aluminum ions and iron ions can be complexed with EDTA, if the EDTA complexometric titration method of Xu Chao and Zhang Xing is used to measure the acid leaching solution, the content of activated alumina measured is relatively high.

Xu Xiaobin et al. (Xu Xiaobin, Yin Suhong, Yang Jianjun, Wen Ziyun. Research on the rapid test method of metakaolin activity [J]. Silicate Bulletin, 2008, 27(4): 690-694.) adopted a similar method, using alumina in The dissolution rate in the acid indicates the activity of metakaolin. The experimental results show that the dissolution rate of alumina in metakaolin has a good correspondence with the compressive strength value of the geopolymer prepared with it, and the compressive strength value of the geopolymer excited by metakaolin with a high alumina dissolution rate is also the same. high. The method only needs 3 hours to detect a sample, and it is a method for quickly testing the activity of metakaolin that can be applied in industrial production. However, under normal temperature conditions, the complexation speed of aluminum ions and EDTA is slow, so an excess of EDTA must be added first, and heating will accelerate the reaction. "Cover the bottle with a watch glass, heat to boil for 3 minutes, and cool to room temperature." Then add the indicator dropwise. Since it needs to be heated and boiled, the indicator can only be added dropwise after cooling, which brings inconvenience to the detection. And this method takes "the indicator changes from yellow to emerald green to grass green as the end point", the color change is not obvious, the titration end point is difficult to judge, and there are many human errors. Therefore, it is necessary to invent a method that can quickly and accurately measure the activity of metakaolin.

Contents of the invention

The purpose of the present invention is to provide a method for detecting the activity of metakaolin with a spectrophotometer, which is simple and convenient in operation, fast in determination and reliable in result.

The technical scheme of the present invention is to carry out acid leaching treatment on metakaolin, then adopt spectrophotometry to measure the aluminum content in the acid leaching solution, and then convert it into the content of activated alumina, so as to calibrate the activity of metakaolin.

The present invention comprises the following steps:

1) Acid leaching treatment of metakaolin:

Pour the metakaolin sample into the container, then add hydrochloric acid, heat in a constant temperature water bath, stir and react, then cool, filter and wash the liquid-solid mixture in the container, transfer the filtrate into a volumetric flask, and add distilled water to constant volume;

2) Preparation of aluminum standard solution:

Put the spectroscopic aluminum flakes in a container, dip and dissolve them with hydrochloric acid until the surface oxide layer is dissolved, pour off the hydrochloric acid solution by pouring, wash and dry, put the aluminum flakes in the container, add aqua regia, heat to dissolve, cool, and move into In the volumetric flask, dilute with distilled water, transfer to the volumetric flask with a pipette gun, dilute with distilled water, and shake well;

3) Drawing of aluminum working standard curve:

Take 1mL, 2mL, 3mL, 4mL, 5mL, 7mL, 9mL, 12mL, 15mL, 18mL, 24mL of 1μg/mL aluminum standard solution respectively in the volumetric flask, add ascorbic acid solution, then add chromazurin-S ethanol solution, and then Add hexamethylenetetramine solution, finally add distilled water to constant volume, then move it into an absorption dish, measure its absorbance at a spectrophotometer wavelength of 545nm, take the mass of aluminum as the abscissa, and the absorbance as the ordinate, draw the aluminum working standard curve , a straight line can be obtained. Find its slope, which is the slope of the aluminum working standard curve;

4) Determination of aluminum content in pickling solution:

Pipette 1mL of metakaolin acid immersion solution with a pipette gun, dilute to 100mL, take 1mL of the diluted metakaolin acid immersion solution in a 50mL volumetric flask, add ascorbic acid, then add chromazurin-S ethanol, and then add hexamethylene Finally, add distilled water to constant volume, then move it into an absorption dish, measure its absorbance at the wavelength of 545nm of the spectrophotometer, and carry out a blank test with the sample for each analysis. The blank test and sample determination use exactly the same reagents and Analysis steps, and carry out parallel operation, the measured absorbance is recorded as blank absorbance, according to the absorbance, the aluminum content m1 in the 50mL sample solution is calculated by using the slope of the aluminum working standard curve:

5) Calculation of active alumina content in metakaolin

The mass fraction of activated alumina is calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Al</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 250</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Al</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

Where _m2 is the mass of metakaolin,

In step 1), the addition of the hydrochloric acid can be in every 1g metakaolin sample, add the hydrochloric acid of 20mL, the mass percent concentration of described hydrochloric acid can be 15%; The temperature of described heating can be 80 ℃, so The time of the stirring reaction can be 2h.

In step 2), the hydrochloric acid can be 1:9 hydrochloric acid, and the washing is preferably first washed with water for 3 times, and then washed with absolute ethanol for 3 times; the quality of the aluminum sheet is preferably 1.0000g, The best amount of adding aqua regia is 10mL.

In step 3), described ascorbic acid solution can be 2.5mL, the ascorbic acid solution that 10g/L prepares now, and described chromazurin-S ethanol solution can be 5mL, 0.3g/L chromazurin-S ethanol solution, so The hexamethylenetetramine solution can be 2.5mL, 300g/L hexamethylenetetramine solution.

In step 4), described ascorbic acid can be 2.5mL, the ascorbic acid that 10g/L mixes now, and described chromazurin-S ethanol can be 5mL, 0.3g/L chromazurin-S ethanol, and described hexamethylene Hexamethylenetetramine can be 2.5mL, 300g/L hexamethylenetetramine.

The invention adopts the chrome azure-S spectrophotometric method to measure the content of aluminum ions in the metakaolin acid dipping solution, and then converts it into the content of activated alumina. The more activated alumina content, the higher the activity of metakaolin. In the method, aluminum is complexed with chromazurin-S, and a purple-red complex is formed in a hexamethylenetetramine medium with a pH of 5.5-6.1. At the same time, ascorbic acid is added to mask the interference of iron, so this method is especially suitable for the determination of active alumina content in iron-stained kaolin. Moreover, the method has the advantages of high sensitivity and precision, less required sample volume, simple operation, fast analysis speed, and low equipment cost.

Description of drawings

Fig. 1 is the aluminum working standard curve of the embodiment of the present invention. In Fig. 1, the abscissa is the aluminum content/μg, and the ordinate is the absorbance.

Detailed ways

The following embodiments will further illustrate the present invention in conjunction with the accompanying drawings.

The absorbance of solutions prepared by adding different volumes of 1 μg/mL aluminum standard solution is shown in Table 1.

Table 1

The working standard curve of aluminum is shown in Figure 1. It can be seen from Figure 1 that the R value of the working standard curve reaches 0.99966, and the linear fitting degree is very good. Its slope is 0.05137.

Example 1

1) Zhangzhou iron dyed kaolin is used as raw material. Among them, the content of Al ₂ O ₃ is 38.24%, and the content of Fe ₂ O ₃ is 0.94%. The main mineral composition is kaolinite and a small amount of quartz, and the mineral structure is flake and a large number of tubes.

2) Calcining Zhangzhou iron-dyed kaolin in a high-temperature energy-saving electric furnace. Kaolin is finely ground and passed through a 100-mesh sieve. The heating rate was 7.5°C/min, the calcination temperatures were 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, and the calcination time was 2h. After the calcination, the kaolin was cooled to room temperature with the furnace, and the metakaolin sample was taken out.

3) Weigh about 1g of metakaolin sample and pour it into a 250mL three-necked flask. Then pour 20mL of 15% hydrochloric acid, heat to 80°C in a constant temperature water bath, and stir for 2h. The liquid-solid mixture in the three-necked flask was cooled, filtered and washed. Transfer the filtrate into a 250mL volumetric flask, add distilled water to volume, and shake well.

4) Use a pipette gun to pipette 1 mL of the metakaolin acid immersion solution and dilute to 100 mL. Take 1mL of the diluted pickling solution in a 50mL volumetric flask. Add 2.5mL, 10g/L fresh ascorbic acid, shake well. Then add 5mL, 0.3g/L chromazurin-S ethanol and shake well. Then add 2.5mL, 300g/L hexamethylenetetramine and shake well. Finally add distilled water to make up to volume and shake well. After thorough mixing, transfer the above solution into a 1cm absorption dish, and measure its absorbance at a spectrophotometer wavelength of 545nm. Simultaneously conduct a blank test.

5) The measurement results are as follows: in the metakaolin obtained by calcination temperatures of 500°C, 600°C, 700°C, 800°C, 900°C, and 1000°C, the contents of activated alumina were 0.37%, 2.95%, 17.84%, and 15.23%, respectively , 15.35%, 0.19%.

6) Adding the metakaolin obtained by the above calcining into water glass to make a geopolymeric cementitious material. The dosing amount of water glass converted into Na ₂ O is 15% of the mass of metakaolin; the modulus of water glass is 1.35; according to the mass ratio, metakaolin: water glass is 0.94. After adding water glass, stir to make a standard consistency slurry, pour it into a 20mm×20mm×20mm steel test mold, and vibrate to form it. The test block is demolded after curing for 24 hours under natural conditions (temperature is (20±5) °C, humidity ≥70%), and the curing is continued, and its compressive strength is measured after 3 days. The measurement of compressive strength is carried out according to the national standard GB/T17671-1999.

7) The measured compressive strengths of the test blocks are: 1.18MPa, 8.95MPa, 55.26MPa, 50.47MPa, 51.89MPa, 0.62MPa. It has a good correspondence with the determined active alumina content.

Example 2

Raw material and analysis test process are with embodiment 1. Kaolin is passed through a 100-mesh sieve. When calcining kaolin, the heating rate is 7.5°C/min, the calcining temperature is 700°C, and the calcining time is 2h, 4h, 6h, 8h, and 10h respectively. The measured activated alumina contents are respectively: 17.84%, 18.72%, 19.02%, 19.56%, 19.86%. The compressive strengths of the prepared geopolymeric cementitious materials are 55.26MPa, 57.59MPa, 58.02MPa, 58.96MPa, 59.46MPa respectively. It has a good correspondence with the determined active alumina content.

Example 3

Raw material and analysis test process are with embodiment 1. Kaolin is passed through a 100-mesh sieve. When calcining kaolin, the heating rates were 2.5°C/min, 5°C/min, 7.5°C/min, and 10°C/min. The calcination temperature is 700° C., and the calcination time is 2 hours respectively. The measured activated alumina contents are respectively: 16.32%, 17.13%, 17.84%, and 18.26%. The compressive strengths of the prepared geopolymeric cementitious materials are 54.78MPa, 54.92MPa, 55.26MPa and 55.56MPa respectively. It has a good correspondence with the determined active alumina content.

Example 4

Raw material and analysis test process are with embodiment 1. The kaolin was passed through a 60-mesh sieve, a 100-mesh sieve, a 120-mesh sieve, and a 140-mesh sieve. When calcining kaolin, the heating rate was 7.5°C/min. The calcination temperature is 700° C., and the calcination time is 2 hours respectively. The measured activated alumina contents are respectively: 17.45%, 17.84%, 18.12%, 18.34%. The compressive strengths of the prepared geopolymeric cementitious materials are 55.02MPa, 55.26MPa, 55.38MPa and 55.65MPa respectively. It has a good correspondence with the determined active alumina content.

Example 5

The analysis and test process is the same as in Example 1. The raw materials are Zhangzhou iron-dyed kaolin, Longyan iron-dyed kaolin, Wuping Xiangdian iron-dyed kaolin and Longyan finished kaolin. Among them, Longyan iron-dyed kaolin contains 35.41% Al ₂ O ₃ and Fe ₂ O ₃ 0.92%; Wuping Xiangdian iron-dyed kaolin contains 34.93% Al ₂ O ₃ and Fe ₂ O ₃ 1.08%; Longyan finished kaolin The Al ₂ O ₃ content is 36.58%, and the Fe ₂ O ₃ content is 0.17%. Kaolin is passed through a 100-mesh sieve. When calcining kaolin, the heating rate was 7.5°C/min. The calcination temperature is 600° C., and the calcination time is 2 hours respectively. The measured activated alumina contents are respectively: 17.84%, 16.15%, 16.03%, and 16.96%. The compressive strengths of the prepared geopolymeric cementitious materials are 55.26MPa, 52.14MPa, 50.98MPa, 53.18MPa respectively. It has a good correspondence with the determined active alumina content.

Claims (9)

1. method of utilizing spectrophotometer to detect activity of metakaolin is characterized in that may further comprise the steps:

1) acidleach of metakaolin is handled:

The metakaolin sample is poured in the container, added hydrochloric acid again, in water bath with thermostatic control, heat, behind the stirring reaction,, filtrate is moved in the volumetric flask adding distil water constant volume the cooling of the liquid-solid mixture in the container, filtration, washing;

2) preparation of aluminum standard solution:

Put specpure aluminium flake in container, molten with the salt acidleach to the surface oxide layer dissolving, with the decantation acid solution that desalts, after the washing, drying places container with aluminium flake, add chloroazotic acid, after the heating for dissolving, cooling moves in the volumetric flask, use distilled water diluting, pipette in the volumetric flask with liquid-transfering gun, use distilled water diluting, shake up;

3) drafting of aluminium working stamndard curve:

Get 1 μ g/mL aluminum standard solution 1mL respectively, 2mL, 3mL, 4mL, 5mL, 7mL, 9mL, 12mL, 15mL, 18mL, 24mL is in volumetric flask, add ascorbic acid solution, the ethanolic solution that adds chromazurine-S then adds hexamethylene tetramine solution again, last adding distil water constant volume, move in the absorption vessel again, measuring its absorbance in spectrophotometer wavelength 545nm place, is horizontal ordinate with the quality of aluminium, and absorbance is an ordinate, draw aluminium working stamndard curve, can get a straight line, go out its slope, be aluminium working stamndard slope of a curve;

4) aluminium Determination on content in the pickle liquor:

Pipette metakaolin pickle liquor 1mL with liquid-transfering gun, be diluted to 100mL, get metakaolin pickle liquor 1mL after the dilution in the 50mL volumetric flask, add ascorbic acid, the ethanolic solution that adds chromazurine-S then, add hexamethylene tetraammonia again, last adding distil water constant volume moves in the absorption vessel again, measure its absorbance in spectrophotometer wavelength 545nm place, the each analysis all carried out blank test in company with sample, and blank test and sample are measured and adopted identical reagent and analytical procedure, and carry out operation repetitive, the absorbance that records, be designated as blank absorbency,, utilize aluminium working stamndard slope of a curve to calculate aluminium content m in the 50mL sample liquid according to absorbance ₁:

5) calculating of activated alumina content in the metakaolin

The massfraction of activated alumina is calculated as follows:

$w\left({\mathrm{Al}}_2{O}_3\right)=\frac{m_1\&times;250\&times;100/w\left(\mathrm{Al}\right)}{m_2}\&times;100\%$

M wherein ₂Be the quality of metakaolin, $w\left(\mathrm{Al}\right)=\frac{2M\left(\mathrm{Al}\right)}{M\left({\mathrm{Al}}_2{O}_3\right)}.$

2. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 1) the addition of described hydrochloric acid is in every 1g metakaolin sample, adds the hydrochloric acid of 20mL.

3. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 1) the mass percent concentration of described hydrochloric acid is 15%.

4. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 1) the temperature of described heating is 80 ℃, and the time of described stirring reaction is 2h.

5. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 2) in, described hydrochloric acid adopts 1: 9 hydrochloric acid.

6. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 2) in, described washing is after washing 3 times earlier with water, uses absolute ethanol washing again 3 times.

7. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1 is characterized in that in step 2) in, the quality of described aluminium flake is 1.0000g, the amount that adds chloroazotic acid is 10mL.

8. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1, it is characterized in that in step 3), described ascorbic acid solution is 2.5mL, the ascorbic acid solution that 10g/L now joins, described chromazurine-S ethanolic solution is 5mL, 0.3g/L chromazurine-S ethanolic solution, described hexamethylene tetramine solution is 2.5mL, the hexamethylene tetramine solution of 300g/L.

9. a kind of method of utilizing spectrophotometer to detect activity of metakaolin as claimed in claim 1, it is characterized in that in step 4), described ascorbic acid is 2.5mL, the ascorbic acid that 10g/L now joins, described chromazurine-S ethanol is 5mL, 0.3g/L chromazurine-S ethanol, described hexamethylene tetraammonia are 2.5mL, the hexamethylene tetraammonia of 300g/L.

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