CN112986304A - Method for qualitative and quantitative analysis of geopolymer components - Google Patents

Abstract

The invention provides a method for qualitatively and quantitatively analyzing geopolymer components, which comprises the following steps: sampling geopolymer and XPS detection²⁹Detecting Si nuclear magnetic resonance; charge correction was performed on the XPS spectra of sample C1 s; qualitatively analyzing the geopolymer according to the corrected XPS full spectrum and the XPS spectrum of Al2 p; according to the chemical shift corresponding to each amorphous aluminosilicate, in²⁹Searching peaks of amorphous phase poly-aluminosilicate in a Si nuclear magnetic resonance spectrum; peak seeking based on Levenberg-Marquardt deconvolution²⁹Carrying out peak-splitting fitting on the Si nuclear magnetic resonance spectrum, and calculating each amorphous phase poly-aluminosilicate Q₄(mAl) molar content ratio; and calculating the mass ratio of each component in the geopolymer according to the qualitative analysis result and the molar content ratio of the geopolymer. The invention can carry out qualitative and quantitative analysis on geopolymer components, and is convenient for accurately knowing the physics and the chemistry of geopolymerThe performance, and then better apply it in the actual engineering.

Description

Method for qualitative and quantitative analysis of geopolymer components

Technical Field

The invention belongs to the technical field of geopolymer research, and particularly relates to a method for qualitatively and quantitatively analyzing geopolymer components.

Background

Geopolymers were formally named in the late 70's of Davidovits, and Olsen, Purdon, and Glucovskij were studied before formally named. At present, geopolymers are being used as novel engineering materials and are gradually applied to the fields of buildings, roads, spaceflight, industry and the like. The geopolymer has the characteristics of quick setting or delayed setting at normal temperature, high temperature resistance, acid resistance, high strength, cyclic utilization, stable performance and the like, so that the geopolymer has the potential of replacing portland cement. By 2020, there are more than ten kinds of geopolymers, divided by the group structure, which are:

-Si-O-Si-O-(poly(siloxo))

-Si-O-Al-O-(poly(sialate))

-Si-O-Al-O-Si-O-(poly(sialate-siloxo))

-Si-O-Al-O-Si-O-Si-O-(poly(sialate-disiloxo))

-P-O-P-O-(poly(phosphate))

-P-O-Si-O-P-O-(poly(phospho-siloxo))

-P-O-Si-O-Al-O-P-O-(poly(phospho-sialate))

-(R)-Si-O-Si-O-(R)(poly-silicone)

-Al-O-P-O-(poly(alumino-phospho))

-Fe-O-Si-O-Al-O-Si-O-(poly(ferro-sialate))。

the common, most widely used polymer is the polymer made of silicon-oxygen tetrahedron (SiO)₄) And alundum tetrahedron (AlO)₄) A polyaluminosilicate geopolymer of composition comprising the group-Si-O-Si-O- (poly (siloxo)), the group-Si-O-Al-O- (poly (sialate)), the group-Si-O-Al-O-Si-O- (poly (sialate-siloxo)), and the group-Si-O-Al-O-Si-O- (poly (sialate-dilloxo)). Each connected with an AlO₄Unit to SiO₄The unit cell is a unit cell, which is composed of a plurality of unit cells,²⁹the chemical shift of Si increases by about 5 ppm.²⁹Chemical shift of nuclear magnetic resonance of Si [ delta ], [²⁹Si) is dependent on²⁹The surrounding of the Si core. Lippmaa et al conducted an exploratory study on silicates of known molecular structure and showed that δ: (A), (B), and (C)²⁹Si) is mainly dependent on SiO₄Degree of polycondensation of the units, δ: (²⁹Si) increases with increasing degree of polymerization. Nuclear Magnetic Resonance (NMR) intensity proportional to presence²⁹The number of Si nuclei, and therefore the content of different silicon-aluminum compounds can be quantitatively analyzed. For easier writing and calculation, the symbol Q describing the aluminosilicate structural units is introduced_n(mAl)。Q_n(mAl) is a traditional form of representing silicoaluminous compounds. Wherein n is each silicon-oxygen tetrahedron (SiO)₄) The number of oxygen atoms shared with adjacent tetrahedra, and m is the amount of Al surrounding the silicon-oxygen tetrahedra. Q₀(mAl) is a single group, Q₁(mAl) is a chain end group, Q₂(mAl) is a chain intermediate, Q₃(mAl) is a lamellar site group, Q₄(mAl) is a three-dimensional network. In the cured geopolymer, the three-dimensional network structure is the main form, so in the NMR peak fitting, for the convenience of analysis, it is assumed that all the components are Q₄(mAl). According to the silicon to aluminum ratio (Si/Al), Q₄The chemical structure classes of (mAl) are: q₄(0Al)，Q₄(1Al)，Q₄(2Al)，Q₄(3Al)，Q₄(4Al)。

The knowledge of the type and content of polyaluminosilicates in the polymerization helps to analyze the physical and chemical properties of the polymer, which is better applied to practical engineering. In general, Q is formed by polymerization in geopolymers₄(0Al)，Q₄The more (1Al), the higher the strength; generated Q₄(3Al)，Q₄The more (4Al), the lower the strength. This is because the bonding force of Al-O bond is weaker than that of Si-O bond because Si-O bond length is 1.61A, Al-O bond length is 1.75A, and Al electronegativity is small.

The currently used means for analyzing components include X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), fourier transform infrared spectroscopy (FTIR), and the like. XRD is generally used to judge the state of compounds (crystalline phase, amorphous phase); XRF can detect elements qualitatively, but cannot analyze the state of combination; FTIR is commonly used for exploring the vibration form and vibration frequency change of chemical bonds before and after polymer reaction, and judging the change of the chemical bonds in the reaction process according to the characteristics of structural groups. At present, the detection means such as XRD, XRF, FTIR and the like are difficult to separately qualitatively and quantitatively analyze the components of the polymer.

Disclosure of Invention

The invention provides a method for qualitatively and quantitatively analyzing components of geopolymers, aiming at accurately knowing physical and chemical properties of geopolymers and further better applying the geopolymers to practical engineering.

The invention adopts the following technical scheme:

a method for qualitative and quantitative analysis of geopolymer composition, comprising the steps of:

s1, sampling the geopolymer to be detected, and carrying out X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron spectroscopy (XPS) on the sample²⁹Si NMR detection (²⁹Si MSA-NMR), and respectively obtaining an XPS spectrum and a nuclear magnetic resonance spectrum of the sample;

s2, sampling XPS spectrum of C1S (abbreviation of 1S atomic orbital of C), and performing charge correction to obtain corrected XPS spectrum;

s3, from the XPS spectrum of the full element and the XPS spectrum of Al2p (abbreviation of Al2p atom orbital), the polymer was qualitatively analyzed;

s4, based on amorphous aluminosilicate Q_nChemical offset Table of (mAl) (Wen end Table 1), finding amorphous phase Polyaluminosilicate Q₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄(0Al) corresponding chemical shift, and obtained in step S1²⁹Q in Si NMR spectrum₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄Performing peak searching in a chemical shift area corresponding to the (0 Al);

s5, based on Levenberg-Marquardt deconvolution method, for the already completed peak searching²⁹Carrying out peak-splitting fitting on the Si nuclear magnetic resonance spectrum to obtain different Q₄(mAl) (where m is 1,2,3,4), and each of the subfunctions is integrated to obtain each of the amorphous aluminosilicate Q₄(mAl) molar content ratio;

and S6, calculating the mass ratio of each component in the geopolymer according to the qualitative analysis result of the geopolymer in the S3 and the molar content ratio in the step S5.

Further, in step S2, calibration is performed using C1S of the extraneous contaminated carbon as a reference peak, the correction value being the difference between the measured value of C1S of the extraneous contaminated carbon and its reference value, and the reference value of C1S being 284.8 eV.

Further, in step S2, the true binding energy of all elements is the sum of the detection value and the correction value.

Further, in step S3, the composition of the polymer is qualitatively analyzed based on the XPS spectrum of Al2p and the full-element XPS spectrum.

Further, the levenberg-marquardt deconvolution method in step S5 is employed

As an operational formula; in the formula, y₀Is the baseline value, A is the area enclosed by the function and the baseline, w is the full width at half maximum, x_cIs the function peak abscissa value.

Compared with the prior art, the invention has the beneficial effects that: at present, the nature of the Chinese medicine cannot be determinedSystematic methods for quantitative analysis of geopolymers (XRD, XRF, FTIR, etc.), the present invention pioneers the use of X-ray photoelectron spectroscopy (XPS) and²⁹si nuclear magnetic resonance method (²⁹Si MSA-NMR) is carried out, and the composition of the geopolymer is qualitatively and quantitatively analyzed based on a Levenbergmarquardt deconvolution method, so that a user can accurately master the type and content of polyaluminosilicate in polymerization according to the method, the method is favorable for analyzing the physical and chemical properties of the geopolymer, and is further better applied to practical engineering.

Drawings

FIG. 1 is an XPS spectrum of example C1s of the present invention;

FIG. 2 is an all-element XPS spectrum of a sample according to an embodiment of the present invention;

FIG. 3 is an XPS spectrum of Al2p of example of the present invention;

FIG. 4 shows an embodiment Q of the present invention₄(mAl) (m ═ 1,2,3,4) chemical shift plot;

FIG. 5 is a graph of a peak-splitting fit for an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the following 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.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention.

The invention discloses a method for qualitatively and quantitatively analyzing geopolymer components, which comprises the following steps:

s1: sampling geopolymers to be detected, respectively making the geopolymers into sheets, and detecting the sheets by X-ray photoelectron spectroscopy (XPS); and making into powder for²⁹Si nuclear magnetic resonance (²⁹Si MSA-NMR), thereby obtaining XPS spectra and²⁹si MSA-NMR spectrum;

s2: performing charge correction on the XPS spectrum of a sample according to the XPS spectrum (shown in figure 1) of C1s (abbreviation of 1s atomic orbit of C) to obtain a corrected XPS full spectrum (shown in figure 2); specifically, the true binding energy of all elements is their detection value + correction value; this is because when an insulator or a semiconductor is measured by XPS, electrons cannot be supplemented due to continuous emission of photoelectrons, so that electron loss occurs on the surface of the sample, which is called "charging effect", which causes a stable potential to occur on the surface of the sample and has a certain constraint effect on escape of electrons, so that the charging effect causes displacement of energy, and the measured binding energy deviates from the true value, resulting in deviation of the test result; when an insulator or a semiconductor is measured by XPS, it is necessary to correct a deviation caused by a charge effect; in the present embodiment, calibration was performed using C1s of the foreign contaminated carbon as a reference peak, that is, the difference between the measured value of C1s of the foreign contaminated carbon and its reference value (284.8eV) was used as a charge correction value (Δ) to correct the binding energy of other elements in the map; in this embodiment, the measured value (284.8eV) of the correction value C1s — the reference value (284.8eV) of C1s is 284.8 eV-0, and since the correction value is 0, the actual detection result of all elements is the true binding energy; if in another example C1s measures 284.5eV, then the correction values are 284.8-284.5 eV-0.3 eV, and the true binding energies for all elements are: the value was found to be +0.3 eV.

S3: according to the corrected XPS survey, it is seen from the corrected XPS survey that it contains the elements Al, Si, C, O, Na excluding the carbon contaminant from the outside, and the main constituent elements of the compound are Al, Si, O, Na, wherein the peak of Al2p (abbreviation of Al2p atom orbital) is 74.2eV (FIG. 3), which is characteristic of the more typical alundum (tetradentate Al (IV)); while the Al2p peak binding energy of aluminoxy octahedra (hexacoordinated Al (VI)) is generally more biased toward 75.0 eV. Geopolymer reaction matrix materials such as metakaolin, usually al (iv), al (vi) are present. The XPS test result of this example shows that the raw material is sufficiently consumed to participate in the reaction, and Al exists in the reaction product in the form of Al (IV). The XPS survey spectrum shows that the elements are mainly Al, Si, O, Na and Al are almost all in the form of Al (IV), which indicates that the obtained geopolymer mainly consists of poly sodium aluminosilicate and has no (or few) other components.

S4: according to an amorphous phase Q_n(mAl) table, see table 1, table 1 presents the chemical migration range of various amorphous aluminosilicate types formed after polymerization of geopolymer gels at temperatures below 500 ℃. The amorphous phase Q is found in Table 1₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al) and Q₄(0Al) corresponding chemical shift; wherein Q is₄(4Al) has a chemical shift of 78 to 82, Q₄(3Al) has a chemical shift of 83 to 89, Q₄(2Al) has a chemical shift of 87 to 94, Q₄(1Al) has a chemical shift of 92 to 100, Q₄The chemical offset of (0Al) is 98-115; thereafter detected in step S1²⁹Finding peaks in corresponding areas in Si nuclear magnetic resonance atlas to obtain Q₄The actual chemical shift of (4Al) is 80.956, Q₄The actual chemical shift of (3Al) is 86.642, Q₄The actual chemical shift of (2Al) is 91.458, Q₄The actual chemical shift of (2Al) is 95.839, Q₄The actual chemical shift of (2Al) was 103.19, see FIG. 4, and peak finding was performed in actual practice using Origin Pro software.

S5: peak seeking based on Levenberg-Marquardt deconvolution²⁹Performing peak-splitting fitting on the Si nuclear magnetic resonance spectrum, and calculating according to a formula to obtain different Q₄(mAl) corresponding subfunctions, and obtaining different Q values by integrating each subfunction₄(mAl) molar content ratio; wherein, adopt

As an operational formula (levenberg-marquardt deconvolution); in the formula, y₀Is the baseline value, A is the area enclosed by the function and the baseline, w is the full width at half maximum, x_cIs the function peak horizontal axis value;

in the present embodiment, each amorphous phase Q obtained by peak seeking according to step S4_n(mAl) ofThe actual chemical shift is x value, namely, the peaks of the nuclear magnetic resonance spectrum are respectively subjected to peak fitting by taking five peaks x as 80.956, 86.642, 91.458, 95.839 and 103.19 as subfunction peaks, so as to obtain Q₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al) and Q₄(0Al) corresponding subfunction as shown in FIG. 5; integrating the subfunction to obtain Q₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄The molar contents of (0Al) were 5.72%, 7.57%, 41.29%, 25.03%, and 20.40%, respectively.

S6: the qualitative analysis of the geopolymer in step S3 shows that the geopolymer in this example is composed mainly of poly sodium aluminosilicate with few other components. And Q₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄The molecular weights of the (0Al) groups correspond to 204, 203, 202, 201, 200, respectively, and Q in the geopolymer to be tested can be calculated from the molar content ratio calculated in step S5₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄The mass ratios of (0Al) were 5.65%, 7.51%, 41.19%, 25.09%, and 20.55%, respectively, as shown in Table 2.

TABLE 2 qualitative and quantitative analysis of geopolymers

Polyaluminosilicates	Integral value	Molar content ratio	Mass ratio of
				Q4(4Al)	50.93	5.72％	5.65％
Q4(3Al)	67.39	7.57％	7.51％
				Q4(2Al)	367.72	41.29％	41.19％
Q4(1Al)	222.88	25.03％	25.09％
				Q4(0Al)	181.64	20.40％	20.55％

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims (5)

1. A method for qualitative and quantitative analysis of geopolymer composition, comprising the steps of:

s1, sampling the geopolymer to be detected, and carrying out X-ray photoelectron spectroscopy analysis and detection on the sample²⁹Performing Si nuclear magnetic resonance detection to respectively obtain an XPS spectrum and a nuclear magnetic resonance spectrum of the sample;

s2, sampling an X-ray photoelectron spectroscopy analysis map of the C1S sample, and performing charge correction on the X-ray photoelectron spectroscopy analysis map to obtain a corrected all-element X-ray photoelectron spectroscopy analysis map;

s3, according to the full-element X-ray photoelectron spectroscopy analysis spectrum and the X-ray photoelectron spectroscopy analysis spectrum of Al2p, the geopolymer is qualitatively analyzed;

s4, based on amorphous aluminosilicate Q_nChemical migration Table of (mAl) to find amorphous phase Polyaluminosilicate Q₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄(0Al) corresponding chemical shift, and obtained in step S1²⁹Q in Si NMR spectrum₄(4Al)、Q₄(3Al)、Q₄(2Al)、Q₄(1Al)、Q₄Performing peak searching in a chemical shift area corresponding to the (0 Al);

s5, based on Levenberg-Marquardt deconvolution method, for the already completed peak searching²⁹Carrying out peak-splitting fitting on the Si nuclear magnetic resonance spectrum to obtain different Q₄(mAl) corresponding subfunctions, and integrating the subfunctions to obtain amorphous aluminosilicate Q₄(mAl) molar content ratio;

and S6, calculating the mass ratio of each component in the geopolymer according to the qualitative analysis result of the geopolymer in the S3 and the molar content ratio in the step S5.

2. The method of claim 1, wherein the charge calibration in step S2 is performed by using the carbon C1S as a reference peak, the calibration is the difference between the measured value of C1S and the reference value of the carbon C1S is 284.8 eV.

3. The method of claim 2, wherein the true binding energy of the total element is the sum of the measured value and the corrected value.

4. The method of claim 2, wherein in step S3, the composition of geopolymer is qualitatively analyzed according to the XPS spectrum of Al2p and the full-element XPS spectrum.

5. The method for qualitative and quantitative analysis of geopolymer composition according to claim 1, wherein Levenberg-Marquardt deconvolution method in step S5 is adopted

As an operational formula; in the formula, y₀Is the baseline value, A is the area enclosed by the function and the baseline, w is the full width at half maximum, x_cIs the function peak abscissa value.

Images