Method for characterizing amorphous phase in geopolymer precursor materials

Abstract

The application provides a method for characterizing amorphous phase in a geopolymer precursor material, which comprises the following steps: firstly, determining a time period (i.e. t1-t2) in which the crystal phase of the geopolymer precursor material is least dissolved in acidolysis; then, performing acidolysis in the time period; and finally, analyzing and comparing filtrates or residues under the acidolysis time t1 and t2, so as to accurately characterize the composition and structure information of the amorphous phase in the geopolymer precursor material. In the method, the mass loss of the geopolymer precursor material after acidolysis is introduced to obtain the solubility of the precursor material under different acidolysis time; then, the amorphous phase content in the geopolymer precursor material after acidolysis under each acidolysis time and the amorphous phase content in the precursor material before acidolysis are determined, so as to obtain the difference between the amorphous phase content in the geopolymer precursor material before acidolysis and under different acidolysis time, and the quantitative results of the dissolved amorphous phase and crystal phase under different acidolysis time are obtained.

Description

Technical Field

[0001] This invention belongs to the field of geopolymer technology, specifically relating to a method for characterizing amorphous phases in geopolymer precursor materials. Background Technology

[0002] Geopolymers are products formed by activating precursor materials containing active aluminosilicates with alkali or silicate solutions. They not only possess properties similar to or even superior to traditional cement concrete, and can replace it in certain applications, but also, because their precursor materials are mostly solid wastes (such as fly ash, bottom ash, slag, steel slag, and red mud), they reduce CO2 release and the extraction of natural resources like limestone compared to cement. As a high-performance and more environmentally friendly building material, the research and development of geopolymers has attracted much attention. To further improve the performance of geopolymer products and achieve efficient and value-added utilization of bulk solid wastes, in-depth research is needed on the composition, structure, and activation mechanism of the active substances in the precursor materials. Based on the properties of the phases, the composition of precursor materials can be mainly divided into amorphous and crystalline phases. Current research results indicate that the active substances in the geopolymer process are mainly provided by the amorphous phase, while the crystalline phase is considered inert and hardly participates in the reaction. However, the amorphous phase may contain crystalline phases during extraction, causing the crystalline phase to obscure the amorphous phase signal during testing and analysis, thus interfering with the amorphous phase and making it difficult to accurately characterize its composition and structure. Therefore, accurately characterizing the composition and structure of amorphous phases in precursor materials has become a pressing problem in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a method for characterizing the amorphous phase in geopolymer precursor materials. The characterization method provided by this invention can accurately characterize the composition and structural information of the amorphous phase in geopolymer precursor materials.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for characterizing amorphous phases in geopolymer precursor materials, comprising the following steps:

[0006] (1) The mass loss of the geopolymer precursor material at different acid hydrolysis times was determined, and the solubility S of the geopolymer precursor material at different acid hydrolysis times was calculated according to Formula I.

[0007]

[0008] Where S is the solubility, in %; m lossdenoted as , where is the mass loss of the geopolymer precursor material, i.e., the mass dissolved during acid hydrolysis of the geopolymer precursor material; m is the mass of the geopolymer precursor material before acid hydrolysis.

[0009] (2) Determine the amorphous phase content in the geopolymer precursor material after acid hydrolysis and the amorphous phase content in the geopolymer precursor material before acid hydrolysis at each acid hydrolysis time in step (1), and obtain the difference A between the amorphous phase content in the geopolymer precursor material before acid hydrolysis and at different acid hydrolysis times; the unit of A is %.

[0010] (3) Calculate the amount of amorphous phase S at each acidolysis time in step (1) according to formulas II and III. A Solubility S of the crystalline phase C ;

[0011] S A +S C =S-type II

[0012] S A -S C =Form A III

[0013] Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%).

[0014] When the solubility S of the crystalline phase at two specific acidolysis times first appears... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference is no more than 3%, the maximum acidolysis time is set to t2;

[0015] (4) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain the first filtrate and the first filter residue; the acid hydrolysis time is t1 obtained in step (3);

[0016] (5) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain a second filtrate and a second filter residue; the acid hydrolysis time is t2 obtained in step (3);

[0017] (6) Analyze the first filtrate obtained in step (4) and the second filtrate obtained in step (5) to obtain the composition and structure information of the amorphous phase in the geopolymer precursor material;

[0018] Alternatively, the first filter residue obtained in step (4) and the second filter residue obtained in step (5) can be analyzed to obtain the composition and structural information of the amorphous phase in the geopolymer precursor material;

[0019] The steps (4) and (5) are not in any particular order.

[0020] Preferably, the geopolymer precursor material in step (1) is one of fly ash, slag, bottom ash and red mud.

[0021] Preferably, the acid solution used in step (1) for acid hydrolysis is a hydrofluoric acid solution with a mass concentration of not more than 1%.

[0022] Preferably, the mass ratio of the geopolymer precursor material to the acid solution is (50-100):1.

[0023] Preferably, the mass ratio of the geopolymer precursor material to the acid solution is (60-90):1.

[0024] Preferably, the different acid hydrolysis times in step (1) are set to 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h and 20h respectively.

[0025] Preferably, the acid hydrolysis in step (1) is carried out under stirring conditions.

[0026] Preferably, the stirring speed is 100-300 r / min.

[0027] Preferably, the stirring speed is 200 r / min.

[0028] Preferably, the amorphous phase content in step (2) is determined by X-ray diffraction.

[0029] This invention provides a method for characterizing the amorphous phase in geopolymer precursor materials. First, the time period (t1 to t2) during acid hydrolysis of the geopolymer precursor material is determined. Then, acid hydrolysis is performed within this time period. By analyzing and comparing the filtrate or residue at acid hydrolysis times t1 and t2, the composition and structure of the amorphous phase in the geopolymer precursor material can be accurately characterized. Specifically, the mass loss of the geopolymer precursor material after acid hydrolysis is introduced to obtain the solubility of the precursor material at different acid hydrolysis times. Then, by measuring the amorphous phase content in the geopolymer precursor material after acid hydrolysis and the amorphous phase content in the precursor material before acid hydrolysis at each acid hydrolysis time, the difference in amorphous phase content between the pre-acid hydrolysis and different acid hydrolysis times is obtained, providing a more realistic quantitative result of the amorphous and crystalline phases dissolved at different acid hydrolysis times. When the amount of crystalline phase dissolved at two specific acid hydrolysis times, S, is first observed... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... CWhen the difference does not exceed 3%, the maximum acidolysis time is set to t2. Experimental results show that when the amorphous phase in fly ash is characterized using the characterization method provided by this invention, between 0.5 and 7 h, 23.24% and 0.74% of the amorphous phase and crystalline phase, respectively, dissolve (the amount of crystalline phase dissolution can be ignored). Attached Figure Description

[0030] Figure 1 The solubility S of fly ash in Example 1 was measured at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h.

[0031] Figure 2 The amorphous phase content in fly ash after acidolysis and the amorphous phase content in fly ash before acidolysis are compared for acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h and 20h in Example 1.

[0032] Figure 3 The amount of amorphous phase dissolved (S) in Example 1 at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h is given. A Solubility S of the crystalline phase C ;

[0033] Figure 4 The corrected infrared absorption spectra I are those obtained before acid hydrolysis and at acid hydrolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h and 12h in Example 1;

[0034] Figure 5 The result is the corrected infrared absorption spectrum deconvolution obtained before acid hydrolysis in Example 1;

[0035] Figure 6 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after acid hydrolysis for 0.5 h;

[0036] Figure 7 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after 1 hour of acid hydrolysis;

[0037] Figure 8 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after acid hydrolysis for 1.5 h;

[0038] Figure 9 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after 3 hours of acid hydrolysis;

[0039] Figure 10 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after 7 hours of acid hydrolysis;

[0040] Figure 11 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after 9 hours of acid hydrolysis;

[0041] Figure 12 The corrected infrared absorption spectrum deconvolution result obtained in Example 1 after 12 hours of acid hydrolysis;

[0042] Figure 13 The images show the BSE diagrams and EDS surface scans of Si (green)-Al (red)-Ca (blue) of the fly ash before acidolysis, the first filter residue after 0.5 hours of acidolysis, and the second filter residue after 7 hours of acidolysis in Example 1.

[0043] Figure 14 The Al / Ca-Si / Ca ratios for the fly ash before acidolysis, the first filter residue after 0.5 hours of acidolysis, and the second filter residue after 7 hours of acidolysis in Example 1 are shown.

[0044] Figure 15 The graph shows the change in the number of pixels in different amorphous aluminosilicate regions in fly ash before acidolysis, first filter residue after 0.5 hours of acidolysis, and second filter residue after 7 hours of acidolysis in Example 1.

[0045] Figure 16 The solubility S of fly ash in Example 2 was measured at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h.

[0046] Figure 17 The amorphous phase content in fly ash after acidolysis and the amorphous phase content in fly ash before acidolysis are compared for acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h and 20h in Example 2.

[0047] Figure 18 The amount of amorphous phase dissolved (S) in Example 2 at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h is given. A Solubility S of the crystalline phase C ;

[0048] Figure 19 The corrected infrared absorption spectra I are those obtained before acid hydrolysis and at acid hydrolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h and 12h in Example 2;

[0049] Figure 20 The corrected infrared absorption spectrum deconvolution result obtained before acid hydrolysis in Example 2;

[0050] Figure 21 The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after acid hydrolysis for 0.5 h;

[0051] Figure 22The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after 1 hour of acid hydrolysis;

[0052] Figure 23 The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after acid hydrolysis for 1.5 h;

[0053] Figure 24 The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after 3 hours of acid hydrolysis;

[0054] Figure 25 The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after 7 hours of acid hydrolysis;

[0055] Figure 26 The corrected infrared absorption spectrum deconvolution result obtained in Example 2 after 9 hours of acid hydrolysis;

[0056] Figure 27 The result is the corrected infrared absorption spectrum deconvolution obtained in Example 2 after 12 hours of acid hydrolysis. Detailed Implementation

[0057] This invention provides a method for characterizing amorphous phases in geopolymer precursor materials, comprising the following steps:

[0058] (1) The mass loss of the geopolymer precursor material at different acid hydrolysis times was determined, and the solubility S of the geopolymer precursor material at different acid hydrolysis times was calculated according to Formula I.

[0059]

[0060] Where S is the solubility, in %; m loss denoted as , where is the mass loss of the geopolymer precursor material, i.e., the mass dissolved during acid hydrolysis of the geopolymer precursor material; m is the mass of the geopolymer precursor material before acid hydrolysis.

[0061] (2) Determine the amorphous phase content in the geopolymer precursor material after acid hydrolysis and the amorphous phase content in the geopolymer precursor material before acid hydrolysis at each acid hydrolysis time in step (1), and obtain the difference A between the amorphous phase content in the geopolymer precursor material before acid hydrolysis and at different acid hydrolysis times; the unit of A is %.

[0062] (3) Calculate the amount of amorphous phase S at each acidolysis time in step (1) according to formulas II and III. A Solubility S of the crystalline phase C ;

[0063] S A +S C =S-type II

[0064] S A -S C =Form A III

[0065] Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%).

[0066] When the solubility S of the crystalline phase at two specific acidolysis times first appears... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference is no more than 3%, the maximum acidolysis time is set to t2;

[0067] (4) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain the first filtrate and the first filter residue; the acid hydrolysis time is t1 obtained in step (3);

[0068] (5) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain a second filtrate and a second filter residue; the acid hydrolysis time is t2 obtained in step (3);

[0069] (6) Analyze the first filtrate obtained in step (4) and the second filtrate obtained in step (5) to obtain the composition and structure information of the amorphous phase in the geopolymer precursor material;

[0070] Alternatively, the first filter residue obtained in step (4) and the second filter residue obtained in step (5) can be analyzed to obtain the composition and structural information of the amorphous phase in the geopolymer precursor material;

[0071] The steps (4) and (5) are not in any particular order.

[0072] This invention measures the mass loss of geopolymer precursor materials at different acidolysis times and calculates the solubility S of geopolymer precursor materials at different acidolysis times according to Formula I.

[0073]

[0074] Where S is the solubility, in %; m loss denoted as , representing the mass loss of the geopolymer precursor material, i.e., the mass dissolved during acid hydrolysis of the geopolymer precursor material; m represents the mass of the geopolymer precursor material before acid hydrolysis.

[0075] In this invention, the geopolymer precursor material is preferably one of fly ash, slag, bottom ash, and red mud. This invention does not have a specific limitation on the source of the geopolymer precursor material; commercially available products well-known to those skilled in the art can be used. This invention also does not have a specific limitation on the particle size of the geopolymer precursor material; particle sizes well-known to those skilled in the art can be used.

[0076] In this invention, the acid solution used for acid hydrolysis is preferably a hydrofluoric acid solution with a mass concentration of not more than 1%. This invention does not impose any special limitations on the source of the acid solution; commercially available products or well-known preparation methods familiar to those skilled in the art can be used.

[0077] In this invention, the mass ratio of the geopolymer precursor material to the acid solution during acid hydrolysis is preferably (50-100):1, more preferably (60-90):1.

[0078] In this invention, the preferred acid hydrolysis times are 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h, respectively. This invention does not impose any specific limitation on the acid hydrolysis temperature; it can be performed at room temperature. Setting the acid hydrolysis time to the aforementioned time intervals ensures that the required characterization time is obtained within the specified acid hydrolysis time.

[0079] In this invention, the acid hydrolysis is preferably carried out under sealed conditions; the acid hydrolysis is preferably carried out under stirring conditions; the stirring speed is preferably 100-300 r / min, more preferably 200 r / min; the stirring is preferably carried out on a variable-speed multifunctional oscillator. This invention does not have a specific limitation on the source of the variable-speed multifunctional oscillator; any instrument or equipment well known to those skilled in the art can be used. In this invention, carrying out the acid hydrolysis under sealed conditions can prevent the volatilization of hydrofluoric acid during the acid hydrolysis process.

[0080] After acid hydrolysis is completed, the product obtained by acid hydrolysis is preferably subjected to vacuum filtration, washing and drying in sequence.

[0081] In this invention, the vacuum filtration is preferably performed using a Buchner funnel and Whatman quantitative filter paper with a pore size of 0.2 μm. This invention does not have any particular limitation on the source of the Buchner funnel and the Whatman quantitative filter paper with a pore size of 0.2 μm; instruments and equipment well known to those skilled in the art can be used.

[0082] In this invention, deionized water is preferably used for washing. This invention does not have a specific limit on the number of washes, as long as the pH of the washing solution is close to neutral. This invention does not have a specific limit on the source of the deionized water; commercially available products well-known to those skilled in the art can be used.

[0083] After washing, the present invention preferably transfers the washed product and Whatman quantitative filter paper to a sample box for drying.

[0084] The present invention does not impose any special limitations on the drying operation; drying to a constant weight is sufficient.

[0085] In this invention, the mass loss m of the geopolymer precursor material loss The preferred method is to use formula IV to calculate:

[0086] M loss =mm residue+filter+box -m filter -m box Formula IV

[0087] Where m is the mass of the geopolymer precursor material before acid hydrolysis; m filter For the quality of Whatman quantitative filter paper; m box For the mass of the sample box; m residue+filter+box It is the sum of the mass of the residual geopolymer precursor material, Whatman quantitative filter paper, and sample box.

[0088] This invention measures the amorphous phase content in the geopolymer precursor material after acidolysis and the amorphous phase content in the geopolymer precursor material before acidolysis at various acidolysis times, obtaining the difference A between the amorphous phase content before acidolysis and at different acidolysis times; the unit of A is _____.

[0089] In this invention, the amorphous phase content is preferably determined by X-ray diffraction. This invention does not impose any specific limitations on the operation of X-ray diffraction for determination; any operation well-known to those skilled in the art can be used.

[0090] After obtaining the solubility S of the geopolymer precursor material at different acidolysis times and the difference A between the amorphous phase content in the geopolymer precursor material before acidolysis and at different acidolysis times, this invention calculates the solubility S of the amorphous phase at each acidolysis time according to Formulas II and III. A Solubility S of the crystalline phase C ;

[0091] S A +S C =S-type II

[0092] S A -S C =Form A III

[0093] Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%).

[0094] When the solubility S of the crystalline phase at two specific acidolysis times first appears... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference is no more than 3%, the maximum acidolysis time is set to t2.

[0095] This invention can determine whether the crystalline phase should continue acid-hydrolyzing by observing the variation in the difference in the amount of crystalline phase dissolved at different acid-hydrolysis times. When the amount of crystalline phase dissolved at two different acid-hydrolysis times first appears to be S... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference does not exceed 3%, the maximum acid hydrolysis time is set as t2. If the difference in the amount of crystalline phase dissolved during the time period t1 to t2 does not exceed 3%, it indicates that the crystalline phase no longer continues to dissolve in large quantities. The amorphous phase is dissolved during this time period, thus obtaining the characterization time of the amorphous phase.

[0096] After obtaining t1, the present invention performs acid hydrolysis on the geopolymer precursor material, and after filtration, obtains the first filtrate and the first filter residue.

[0097] In this invention, the acid hydrolysis time is t1.

[0098] In this invention, the acid hydrolysis of the geopolymer precursor material is preferably the same as the aforementioned operation, and will not be repeated here.

[0099] In this invention, the filtration is preferably vacuum filtration; the vacuum filtration is preferably the same as the aforementioned operation, and will not be repeated here.

[0100] After filtration, the present invention preferably washes and dries the filtered product in sequence to obtain a first filtrate and a first filter residue.

[0101] In this invention, the washing and drying are preferably the same as the aforementioned operations, and will not be repeated here.

[0102] After obtaining t2, the present invention performs acid hydrolysis on the geopolymer precursor material, and after filtration, obtains the second filtrate and the second filter residue.

[0103] In this invention, the acid hydrolysis time is t2.

[0104] In this invention, the acid hydrolysis of the geopolymer precursor material is preferably the same as the aforementioned operation, and will not be repeated here.

[0105] In this invention, the filtration is preferably vacuum filtration; the vacuum filtration is preferably the same as the aforementioned operation, and will not be repeated here.

[0106] After filtration, the present invention preferably washes and dries the filtered product in sequence to obtain a second filtrate and a second filter residue.

[0107] In this invention, the washing and drying are preferably the same as the aforementioned operations, and will not be repeated here.

[0108] After obtaining the first filtrate, the first filter residue, the second filtrate, and the second filter residue, the present invention analyzes the first filtrate and the second filtrate to obtain the composition and structural information of the amorphous phase in the geopolymer precursor material;

[0109] Alternatively, the first and second filter residues can be analyzed to obtain information on the composition and structure of the amorphous phase in the geopolymer precursor material.

[0110] In this invention, the analysis preferably obtains the composition of the amorphous phase according to formula V;

[0111] D A =D t1 -D t2 Formula V

[0112] Among them, D A Information on the composition and structure of the acid-hydrolyzed amorphous phase; D t1 This provides information on the composition and structure of the amorphous phase at acidolysis time t1; D t2 This provides information on the composition and structure of the amorphous phase at acidolysis time t2.

[0113] In this invention, D A It refers to a broad range of experimental data, including data from various analytical tests (such as NMR and backscattering), without fixed units. Analysis of this data can reveal the composition and structure of the acid-hydrolyzed amorphous phase; D t1 and D t2 With D A Similarly, it also includes a broad range of experimental data, such as data obtained from NMR and backscattered magnetic resonance (NMR) tests. After obtaining the corresponding test data, the former's test data (D) t1 Subtract the latter's test data (D) t2 This allows us to obtain NMR and backscatter data of the acid-hydrolyzed amorphous phase. By analyzing this data, we can obtain the composition and structural information of the acid-hydrolyzed amorphous phase.

[0114] This invention provides a method for characterizing the amorphous phase in geopolymer precursor materials. First, the time period (t1 to t2) during acid hydrolysis of the geopolymer precursor material is determined. Then, acid hydrolysis is performed within this time period. By analyzing and comparing the filtrate or residue at acid hydrolysis times t1 and t2, the composition and structure of the amorphous phase in the geopolymer precursor material can be accurately characterized. Specifically, the mass loss of the geopolymer precursor material after acid hydrolysis is introduced to obtain the solubility of the precursor material at different acid hydrolysis times. Then, by measuring the amorphous phase content in the geopolymer precursor material after acid hydrolysis and the amorphous phase content in the precursor material before acid hydrolysis at each acid hydrolysis time, the difference in amorphous phase content between the pre-acid hydrolysis and different acid hydrolysis times is obtained, providing a more realistic quantitative result of the amorphous and crystalline phases dissolved at different acid hydrolysis times. When the amount of crystalline phase dissolved at two specific acid hydrolysis times, S, is first observed... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference is no more than 3%, the maximum acidolysis time is set to t2.

[0115] The characterization method provided by this invention can extract the active amorphous phase in alkali-activated geopolymer precursor materials, thereby helping to gain a deeper understanding of the composition, structure, and activation mechanism of active substances during the alkali-activated reaction. Ultimately, it provides guidance for the preparation of higher-performance geopolymer products and improves the efficient and value-added utilization of bulk solid waste. Since the mass loss of the geopolymer precursor material after acid hydrolysis is incorporated into the XRD quantitative analysis, more realistic quantitative results of the dissolved amorphous and crystalline phases at different acid hydrolysis times are obtained, and the results are more reliable. This invention has universality and flexibility and is applicable to the characterization of active amorphous phases in various alkali-activated geopolymer precursor materials.

[0116] To verify the accuracy of the characterization time (t1 and t2) of the amorphous phase in the characterization method provided by the present invention, the present invention preferably uses Fourier transform infrared spectroscopy to determine the amorphous and crystalline phases in the geopolymer precursor material before acid hydrolysis and the geopolymer precursor material after acid hydrolysis at various acid hydrolysis times, to obtain the original infrared absorption spectrum I0, and then calculate the corrected infrared absorption spectrum I according to formula VI.

[0117] I = I0 × (IS) VI

[0118] Where I is the corrected infrared absorption spectrum I; I0 is the original infrared absorption spectrum; and S is the solubility at each acidolysis time, in percentage.

[0119] To further obtain the changes in amorphous and crystalline phases with acid hydrolysis time, this invention performs Fourier transform infrared spectroscopy on the precursor materials before and after acid hydrolysis. Then, Formula VI is introduced to correct the original infrared absorption spectrum. Finally, the corrected infrared absorption spectrum is quantitatively analyzed. By comparing the changes in typical infrared characteristic peaks representing the amorphous and crystalline phase structures in the infrared spectrum, the changing trends of dissolved amorphous and crystalline phases in the precursor materials at different acid hydrolysis times are obtained, thereby determining the optimal acid hydrolysis time. The result is compared with the acid hydrolysis time (t1~t2) in the characterization method provided by this invention, thus proving the accuracy of the characterization method of this invention.

[0120] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0121] Example 1

[0122] The characterization method for amorphous phases in fly ash includes the following steps:

[0123] (1) The mass loss of fly ash with a particle size <74μm (denoted as FA-F) under sealed conditions at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h was measured, and the solubility S of the fly ash at each acidolysis time was calculated according to Formula I; the results are as follows. Figure 1 As shown, from Figure 1 The solubility S of fly ash under different acid hydrolysis times can be observed.

[0124]

[0125] Where S is the solubility, in %; m loss denoted as ρ, which represents the mass loss of fly ash, i.e., the mass dissolved during acid hydrolysis; m represents the mass of fly ash before acid hydrolysis.

[0126] The acid solution used for acid hydrolysis is a 1% hydrofluoric acid solution. The mass ratio of fly ash to acid solution is 100:1. Acid hydrolysis is carried out under stirring conditions at a speed of 200 r / min. The stirring is carried out on a variable speed multi-functional shaker.

[0127] After acid hydrolysis, the product obtained from acid hydrolysis was vacuum filtered using a Buchner funnel and Whatman quantitative filter paper with a pore size of 0.2 μm. It was then washed with deionized water until the pH of the washing solution was close to neutral. The washed product and Whatman quantitative filter paper were then transferred to a sample box and dried in an oven at 50°C for 6 hours to obtain the sum of the masses of residual fly ash, Whatman quantitative filter paper, and sample box, m. residue+filter+box ;

[0128] mass loss of fly ash m loss The following calculations were performed using Equation IV:

[0129] M loss =mm residue+filter+box -m filter -m box Formula IV

[0130] Where m is the mass of fly ash before acid hydrolysis; m filter For the quality of Whatman quantitative filter paper; m box For the mass of the sample box; m residue+filter+box The sum of the mass of residual fly ash, Whatman quantitative filter paper, and sample box;

[0131] (2) The content of amorphous phase in the fly ash after acidification and the content of amorphous phase in the fly ash before acidification at each acidification time in step (1) were determined by X-ray diffraction. The results are as follows: Figure 2 As shown, according to Figure 2 The difference A (in %) in the amorphous phase content of fly ash before acid hydrolysis and at different acid hydrolysis times can be obtained.

[0132] (3) Calculate the amount of amorphous phase S at each acidolysis time in step (1) according to formulas II and III. A Solubility S of the crystalline phase C ;

[0133] S A +S C =S-type II

[0134] S A -S C =Form A III

[0135] Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%).

[0136] Solubility S of amorphous phase at various acidolysis times A Solubility S of the crystalline phase C The result is as follows Figure 3 As shown, from Figure 3It can be seen that the solubility S of the crystalline phase first appears in the range of 0.5–1 h. C The difference does not exceed 3%, therefore, t1 is 0.5h; the solubility S of the crystalline phase under acidolysis time from 0.5h to 7h. C The difference does not exceed 3%, therefore, t2 is 7h (between 0.5 and 7h, the amorphous phase dissolved 23.24%, the crystalline phase dissolved 0.74%, and the amount of crystalline phase dissolved S). C The difference should not exceed 3%;

[0137] (4) The geopolymer precursor material was acid-hydrolyzed for 0.5 h, and then vacuum filtered, washed and dried in sequence to obtain the first filtrate and the first filter residue.

[0138] (5) The geopolymer precursor material was acid-hydrolyzed for 7 hours, and then vacuum-filtered, washed and dried in sequence to obtain the second filtrate and the second filter residue.

[0139] (6) Analyze the first filtrate obtained in step (4) and the second filtrate obtained in step (5) to obtain the composition and structure information of the amorphous phase in the geopolymer precursor material;

[0140] The analysis yielded the composition of the amorphous phase according to formula V;

[0141] D A =D t1 -D t2 Formula V

[0142] Among them, D A Information on the composition and structure of the acid-hydrolyzed amorphous phase; D t1 This provides information on the composition and structure of the amorphous phase at acidolysis time t1; D t2 This provides information on the composition and structure of the amorphous phase at acidolysis time t2.

[0143] To verify the accuracy of t1 and t2 in Example 1, Fourier transform infrared spectroscopy was used to determine the amorphous and crystalline phases in the fly ash before acid lysis and after acid lysis at various acid lysis times, obtaining the original infrared absorption spectrum I0. Then, the corrected infrared absorption spectrum I was calculated according to Equation VI, and the results are as follows. Figure 4 As shown, for Figure 4 The corrected infrared absorption spectrum I was deconvolved, and the result... Figures 5-12 As shown, from Figures 5-12 It can be seen that the area of ​​the characteristic peaks (F1, F6 and F7) representing the crystalline phase structure hardly decreases between 0.5 and 7 hours, while the area of ​​the characteristic peak (F4) representing the amorphous phase structure continues to decrease. This indicates that the crystalline phase hardly dissolves between 0.5 and 7 hours of acid hydrolysis, while the amorphous phase continues to dissolve. This is consistent with the results calculated in Example 1.

[0144] I = I0 × (IS) VI

[0145] Where I is the corrected infrared absorption spectrum I; I0 is the original infrared absorption spectrum; and S is the solubility at each acidolysis time, in percentage.

[0146] BSE images and Si (green)-Al (red)-Ca (blue) EDS surface scan images of fly ash before acid lysis (0h acid lysis), the first filter residue after 0.5h acid lysis (i.e., residual FA-W), and the second filter residue after 7h acid lysis (i.e., residual FA-W) are shown below. Figure 13 As shown, (a) is the BSE plot, and (b) is the EDS surface scan plot of Si (green)—Al (red)—Ca (blue). The Al / Ca—Si / Ca plots of fly ash before acid leaching (0h acid leaching), the first filter residue after 0.5h acid leaching, and the second filter residue after 7h acid leaching are shown below. Figure 14 As shown in the figure. The changes in the number of pixels in different amorphous aluminosilicate regions in fly ash before acidification (0h acidification), the first filter residue after 0.5h acidification, and the second filter residue after 7h acidification are shown in the figure. Figure 15 As shown, by utilizing the three lines Si / Ca=1, Al / Ca=1, and Si / Al=1, the Al / Ca—Si / Ca diagram is divided into six amorphous aluminosilicate regions. Figure 14 (1) Calcium-rich aluminosilicate-1 (Ca>Al>Si, Region I); (2) Calcium-rich aluminosilicate-2 (Ca>Si>Al, Region II); (3) Low to medium calcium aluminosilicate (Si>Ca>Al, Region III); (4) Low calcium aluminosilicate (Si>Al>Ca, Region IV); (5) Aluminum-rich calcium silicate-1 (Al>Si>Ca, Region V); (6) Aluminum-rich calcium silicate-2 (Al>Ca>Si, Region VI).

[0147] The changes in the number of pixels in different amorphous aluminosilicate regions were statistically analyzed. Figure 15 It should be noted that a decrease in the number of pixels within a region indicates that the corresponding phase has dissolved, which leads to a relative increase in the number of pixels in other regions. Therefore, it can be concluded that the amorphous aluminosilicates dissolved within 0.5 h include calcium-rich aluminosilicate-2 (Ca>Si>Al, region II), low- to medium-calcium aluminosilicates (Si>Ca>Al, region III), and low-calcium aluminosilicates (Si>Al>Ca, region IV), which dissolved at 32.4%, 49%, and 50.3%, respectively. The decrease in the cumulative heat of reaction of residual FA during acid hydrolysis for 0.5 h is mainly attributed to the dissolution of these three amorphous aluminosilicates.

[0148] When the acidolysis time was extended from 0.5 h to 7 h, only the amorphous aluminosilicate in region IV showed a dissolved state (6.6% dissolved) as the residual HF concentration decreased, leading to a further decrease in the cumulative heat of reaction. In contrast, calcium-rich calcium silicate-1 (Ca>Al>Si, region I), aluminum-rich calcium silicate-2 (Al>Si>Ca, region V), and aluminum-rich calcium silicide-2 (Aluminum>Ca>Si, region VI) increased between 0.5 h and 7 h of acidolysis, and the total increase of these three phases was greater than the decrease of the low-calcium aluminosilicate (Si>Al>Ca, region IV). However, since this did not lead to an increase in the cumulative heat of reaction of the residual FA-W at 7 h of acidolysis, we infer that the amorphous aluminosilicates in regions I, V, and VI exhibit no reactivity or very low reactivity, while the amorphous aluminosilicates in regions II, III, and IV are the main reactive amorphous phases.

[0149] Furthermore, we found that reactive amorphous aluminosilicates, namely calcium-rich aluminosilicate-2 (Ca>Si>Al, Region II), low- to medium-calcium aluminosilicates (Si>Ca>Al, Region III), and low-calcium aluminosilicates (Si>Al>Ca, Region IV), all have Si / Al ratios greater than 1; while non-reactive amorphous aluminosilicates, namely calcium-rich aluminosilicate-1 (Ca>Al>Si, Region I), aluminum-rich calcium silicate-1 (Al>Si>Ca, Region V), and aluminum-rich calcium silicate-2 (Al>Ca>Si, Region VI), all have Si / Al ratios less than 1. Therefore, we conclude that amorphous aluminosilicates with a Si / Al ratio greater than 1 tend to have higher reactivity.

[0150] In summary, the acid hydrolysis method combined with SEM-EDS analysis can successfully extract and analyze amorphous aluminosilicates in fly ash. The results show that amorphous aluminosilicates in fly ash can be divided into six types: (1) calcium-rich aluminosilicate-1 (Ca>Al>Si, region I); (2) calcium-rich aluminosilicate-2 (Ca>Si>Al, region II); (3) low to medium calcium aluminosilicates (Si>Ca>Al, region III); (4) low calcium aluminosilicates (Si>Al>Ca, region IV); (5) aluminum-rich calcium silicate-1 (Al>Si>Ca, region V); and (6) aluminum-rich calcium silicate-2 (Al>Ca>Si, region VI). Among them, only calcium-rich aluminosilicate-2 (Ca>Si>Al, region II), low to medium calcium aluminosilicates (Si>Ca>Al, region III), and low calcium aluminosilicates (Si>Al>Ca, region IV) are reactive. Furthermore, it can be concluded that amorphous aluminosilicates rich in calcium and with a Si / Al ratio greater than 1 tend to have higher reactivity.

[0151] Example 2

[0152] The characterization method for amorphous phases in fly ash includes the following steps:

[0153] (1) The mass loss of fly ash with a particle size >74μm (denoted as FA-C) under sealed conditions at acidolysis times of 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h, and 20h was measured, and the solubility S of fly ash at each acidolysis time was calculated according to Formula I; the results are as follows. Figure 16 As shown, from Figure 16 The solubility S of fly ash under different acid hydrolysis times can be observed.

[0154]

[0155] Where S is the solubility, in %; m loss denoted as ρ, which represents the mass loss of fly ash, i.e., the mass dissolved during acid hydrolysis; m represents the mass of fly ash before acid hydrolysis.

[0156] The acid solution used for acid hydrolysis is a 1% hydrofluoric acid solution. The mass ratio of fly ash to acid solution is 100:1. Acid hydrolysis is carried out under stirring conditions at a speed of 200 r / min. The stirring is carried out on a variable speed multi-functional shaker.

[0157] After acid hydrolysis, the product obtained from acid hydrolysis was vacuum filtered using a Buchner funnel and Whatman quantitative filter paper with a pore size of 0.2 μm. It was then washed with deionized water until the pH of the washing solution was close to neutral. The washed product and Whatman quantitative filter paper were then transferred to a sample box and dried in an oven at 50°C for 6 hours to obtain the sum of the masses of residual fly ash, Whatman quantitative filter paper, and sample box, m. residue+filter+box ;

[0158] mass loss of fly ash m loss The following calculations were performed using Equation IV:

[0159] M loss =mm residue+filter+box -m filter -m box Formula IV

[0160] Where m is the mass of fly ash before acid hydrolysis; m filter For the quality of Whatman quantitative filter paper; m box For the mass of the sample box; m residue+filter+box The sum of the mass of residual fly ash, Whatman quantitative filter paper, and sample box;

[0161] (2) The content of amorphous phase in the fly ash after acidification and the content of amorphous phase in the fly ash before acidification at each acidification time in step (1) were determined by X-ray diffraction. The results are as follows: Figure 17 As shown, according to Figure 17 The difference A (in %) in the amorphous phase content of fly ash before acid hydrolysis and at different acid hydrolysis times can be obtained.

[0162] (3) Calculate the amount of amorphous phase S at each acidolysis time in step (1) according to formulas II and III. A Solubility S of the crystalline phase C ;

[0163] S A +S C =S-type II

[0164] S A -S C =Form A III

[0165] Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%).

[0166] Solubility S of amorphous phase at various acidolysis times A Solubility S of the crystalline phase C The result is as follows Figure 18 As shown, from Figure 18 It can be seen that the solubility S of the crystalline phase first appears in the range of 0.5–1 h. C The difference does not exceed 3%, therefore, t1 is 0.5h; the solubility S of the crystalline phase from 0.5h to 9h acidolysis time. C The difference does not exceed 3%, therefore, t2 is 9h (between 0.5 and 9h, the amorphous phase dissolved 26.32%, the crystalline phase dissolved 1.81%, and the amount of crystalline phase dissolved S). C The difference should not exceed 3%;

[0167] (4) The geopolymer precursor material was acid-hydrolyzed for 0.5 h, and then vacuum filtered, washed and dried in sequence to obtain the first filtrate and the first filter residue.

[0168] (5) The geopolymer precursor material was acid-hydrolyzed for 9 hours, and then vacuum filtered, washed and dried in sequence to obtain the second filtrate and the second filter residue.

[0169] (6) Analyze the first filtrate obtained in step (4) and the second filtrate obtained in step (5) to obtain the composition and structure information of the amorphous phase in the geopolymer precursor material;

[0170] The analysis yielded the composition of the amorphous phase according to formula V;

[0171] D A =D t1 -D t2 Formula V

[0172] Among them, D A Information on the composition and structure of the acid-hydrolyzed amorphous phase; D t1 This provides information on the composition and structure of the amorphous phase at acidolysis time t1; D t2 This provides information on the composition and structure of the amorphous phase at acidolysis time t2.

[0173] To verify the accuracy of t1 and t2 in Example 2, Fourier transform infrared spectroscopy was used to determine the amorphous and crystalline phases in the fly ash before acidification and after acidification at various acidification times, obtaining the original infrared absorption spectrum I0. Then, the corrected infrared absorption spectrum I was calculated according to Equation VI, and the results are as follows. Figure 19 As shown, for Figure 19 The corrected infrared absorption spectrum I was deconvolved, and the result... Figures 20-27 As shown, from Figures 20-27 It can be seen that the area of ​​the characteristic peaks (C7 and C8) representing the crystalline phase structure hardly decreases between 0.5 and 9 hours, while the area of ​​the characteristic peak (C4) representing the amorphous phase structure continues to decrease. This indicates that the crystalline phase hardly dissolves between 0.5 and 9 hours of acid hydrolysis, while the amorphous phase continues to dissolve. This is consistent with the results calculated in Example 2.

[0174] I = I0 × (IS) VI

[0175] Where I is the corrected infrared absorption spectrum I; I0 is the original infrared absorption spectrum; and S is the solubility at each acidolysis time, in percentage.

[0176] As can be seen from the above embodiments, the characterization method provided by the present invention can accurately characterize the composition and structural information of the amorphous phase in geopolymer precursor materials.

[0177] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for characterizing the amorphous phase in geopolymer precursor materials, comprising the following steps: (1) The mass loss of the geopolymer precursor material at different acid hydrolysis times was determined, and the solubility S of the geopolymer precursor material at different acid hydrolysis times was calculated according to Formula I. Where S is the solubility, in %; m loss denoted as , where is the mass loss of the geopolymer precursor material, i.e., the mass dissolved during acid hydrolysis of the geopolymer precursor material; m is the mass of the geopolymer precursor material before acid hydrolysis. (2) Determine the amorphous phase content in the geopolymer precursor material after acid hydrolysis and the amorphous phase content in the geopolymer precursor material before acid hydrolysis at each acid hydrolysis time in step (1), and obtain the difference A between the amorphous phase content in the geopolymer precursor material before acid hydrolysis and at different acid hydrolysis times; the unit of A is %. (3) Calculate the amount of amorphous phase S at each acidolysis time in step (1) according to formulas II and III. A Solubility S of the crystalline phase C ; S A +S C =S-type II S A -S C = A Formula III Among them, S A Solubility of the amorphous phase, expressed as a percentage (%); S C Solubility of the crystalline phase, expressed as a percentage (%). When the solubility S of the crystalline phase at two specific acidolysis times first appears... C When the difference does not exceed 3%, the first endpoint of this acidolysis time period is set as t1; when the solubility S of the crystalline phase is between t1 and a certain maximum acidolysis time... C When the difference is no more than 3%, the maximum acidolysis time is set to t2; (4) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain the first filtrate and the first filter residue; the acid hydrolysis time is t1 obtained in step (3); (5) The geopolymer precursor material is acid-hydrolyzed and filtered to obtain a second filtrate and a second filter residue; the acid hydrolysis time is t2 obtained in step (3); (6) Analyze the first filtrate obtained in step (4) and the second filtrate obtained in step (5) to obtain the composition and structure information of the amorphous phase in the geopolymer precursor material; Alternatively, the first filter residue obtained in step (4) and the second filter residue obtained in step (5) can be analyzed to obtain the composition and structural information of the amorphous phase in the geopolymer precursor material; The steps (4) and (5) are not in any particular order.

2. The characterization method according to claim 1, characterized in that, In step (1), the geopolymer precursor material is one of fly ash, slag, bottom ash, and red mud.

3. The characterization method according to claim 1, characterized in that, The acid solution used in step (1) for acid hydrolysis is a hydrofluoric acid solution with a mass concentration of no more than 1%.

4. The characterization method according to claim 3, characterized in that, The mass ratio of the geopolymer precursor material to the acid solution is (50-100):

1.

5. The characterization method according to claim 4, characterized in that, The mass ratio of the geopolymer precursor material to the acid solution is (60-90):

1.

6. The characterization method according to claim 1, characterized in that, The different acid hydrolysis times in step (1) are set as follows: 0.5h, 1h, 1.5h, 3h, 7h, 9h, 12h, 16h and 20h.

7. The characterization method according to claim 1, characterized in that, The acid hydrolysis in step (1) is carried out under stirring conditions.

8. The characterization method according to claim 7, characterized in that, The stirring speed is 100-300 r / min.

9. The characterization method according to claim 8, characterized in that, The stirring speed is 200 r / min.

10. The characterization method according to claim 1, characterized in that, The amorphous phase content in step (2) is determined by X-ray diffraction.

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