A method for predicting the electron transfer capacity of iron-modified biochar

Abstract

The present invention provides a method for predicting the electron transfer capacity of iron-modified biochar, comprising the steps of: S1. determining the C, O and Fe structures in the iron-modified biochar; S2. typing the C, O and Fe structures in the iron-modified biochar and quantifying their ratios; S3. determining the electron transfer capacity of the iron-modified biochar; S4. establishing a prediction model for the electron transfer capacity of the iron-modified biochar to predict the electron transfer capacity of the iron-modified biochar. The method of the present invention predicts the electron transfer capacity of the iron-modified biochar by quantifying the ratio of the C, O and Fe structures, thereby solving the problem of the lack of a method for predicting the electron transfer capacity of the current iron-modified biochar.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to a method for predicting the electron transfer ability of iron-modified biochar. Background Art

[0002] Iron-modified biochar is widely used in the field of environmental remediation, and the electron transfer capacity is a key factor in improving the utilization efficiency of iron-modified biochar. However, due to the variety of iron types and modification methods, such as liquid phase reduction, carbon thermal reduction, hydrothermal carbonization, impregnation / impregnation pyrolysis, etc., the electron transfer capacity of iron-modified biochar prepared by different methods varies greatly. The traditional electrochemical workstation is complex, time-consuming, and costly to determine the electron transfer capacity. It is particularly important to establish a method to predict the electron transfer capacity of iron-modified biochar.

[0003] The C, O and Fe structures in iron-modified biochar are the main components that determine its electron transfer capacity and have a good response to changes in modification parameters. Therefore, establishing a prediction method for the electron transfer capacity of iron-modified biochar based on the C, O and Fe structures has a good guiding significance for the optimized preparation and application of iron-modified biochar. Summary of the invention

[0004] The present invention provides a method for predicting the electron transfer capacity of iron-modified biochar. The electron transfer capacity of iron-modified biochar is predicted by quantifying the structural ratios of C, O and Fe, thereby solving the problem of lack of current methods for predicting the electron transfer capacity of iron-modified biochar.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] The method for predicting the electron transfer capacity of iron-modified biochar of the present invention comprises the following steps: S1. determining the C, O and Fe structures in the iron-modified biochar; S2. typing the C, O and Fe structures in the iron-modified biochar and quantifying their ratios; S3. determining the electron transfer capacity of the iron-modified biochar; S4. establishing a prediction model for the electron transfer capacity of the iron-modified biochar to predict the electron transfer capacity of the iron-modified biochar.

[0007] Preferably, in the above method for predicting the electron transfer capacity of iron-modified biochar, in step S1, an X-ray fluorescence analyzer is used to obtain the C, O and Fe structures in the iron-modified biochar.

[0008] Preferably, in the above-mentioned method for predicting the electron transfer capacity of iron-modified biochar, in step S2, a Gaussian model is used to classify the C, O and Fe structures in the iron-modified biochar and quantify their proportions, wherein the C structure includes -C=C / CC, COC / C-OH, O=C-OH, the O structure includes C=O, C-OH, OC=O, and the Fe structure includes hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2), Fe2p1 / 2.

[0009] Preferably, in the above-mentioned method for predicting the electron transfer ability of iron-modified biochar, in step S3, the electron transfer ability of the iron-modified biochar is determined by a redox method, and the reaction system used in the redox method includes an electrochemical workstation and a three-electrode system, an Ag / AgCl electrode is used as a reference electrode, and a platinum sheet electrode is used as a counter electrode.

[0010] Preferably, in the above-mentioned method for predicting the electron transfer capacity of iron-modified biochar, in step S4, the structural ratios of C, O and Fe are used as dependent variables, and -C=C / CC, COC / C-OH, O=C-OH, C=O, C-OH, OC=O, hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2) and Fe2p1 / 2 ratio were used as independent variables for regression analysis, and a stepwise regression model was constructed. After eliminating the insignificant items with p>0.05, the optimal model was obtained: y=9.68×10 -5 +3.79×10 -6 X9-4.82×10 -6 X6-2.09×10 -6 X5, R 2 =1.0, where: X5 is the percentage of C-OH content, X6 is the percentage of OC=O content, X9 is the percentage of Fe 3+ (2p1 / 2) content percentage, R 2 is the goodness of fit, that is, the coefficient of certainty of the equation.

[0011] The beneficial effects of the present invention are:

[0012] The method of the present invention takes into account the influence of the structural ratio of C, O and Fe on the electron transfer capacity of iron-modified biochar, and adopts a stepwise regression method to establish a correlation model between the structural ratio of C, O and Fe of iron-modified biochar and the electron transfer capacity, using -C=C / CC, COC / C-OH, O=C-OH, C=O, C-OH, OC=O, hematite Fe(III), Fe2p3 / 2, Fe 3+The method for predicting the electron transfer capacity of the iron-modified biochar of the present invention is simple to operate, has good predictability and strong applicability, and has a good guiding significance for optimizing the repair efficiency of the iron-modified biochar and its application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation or the description of the prior art are briefly introduced below.

[0014] Figure 1 is a flow chart of a method for predicting the electron transfer capacity of iron-modified biochar according to the present invention;

[0015] Figure 2 is the correlation between the measured and predicted values ​​of the electron transfer capacity of iron-modified biochar;

[0016] Figure 3 Validation of a predictive model for the electron transfer capacity of iron-modified biochar. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0018] like Figure 1 As shown, the method for predicting the electron transfer capacity of iron-modified biochar of the present invention comprises the following steps:

[0019] S1. Determination of C, O and Fe structures in iron-modified biochar.

[0020] X-ray fluorescence analyzer was used to obtain the C, O and Fe structures in iron-modified biochar.

[0021] S2. Classify the C, O, and Fe structures in iron-modified biochar and quantify their ratios.

[0022] The Gaussian model was used to classify the C, O, and Fe structures in the iron-modified biochar and quantify their proportions. Among them, the C structures include -C=C / CC, COC / C-OH, O=C-OH, the O structures include C=O, C-OH, OC=O, and the Fe structures include hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2), Fe2p1 / 2.

[0023] S3. Determination of the electron transfer capacity of iron-modified biochar.

[0024] The electron transfer capacity of iron-modified biochar was determined by redox method. The reaction system used in the redox method included an electrochemical workstation and a three-electrode system (Ag / AgCl electrode as a reference electrode and a platinum electrode as a counter electrode).

[0025] S4. Establish a prediction model for the electron transfer capacity of iron-modified biochar to predict the electron transfer capacity of iron-modified biochar.

[0026] The structural ratios of C, O, and Fe were used as dependent variables, and -C=C / CC, COC / C-OH, O=C-OH, C=O, C-OH, OC=O, hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2) and Fe2p1 / 2 ratio were included in the independent variables for regression analysis, and a stepwise regression model was constructed. Considering the possible interaction between the variables, the stepwise regression method was used for modeling, and the insignificant items with p>0.05 were eliminated to obtain the optimal model to predict the electron transfer capacity of iron-modified biochar. A method for predicting the electron transfer capacity of iron-modified biochar based on C, O and Fe structures was established.

[0027] The established prediction model equation for the electron transfer capacity of iron-modified biochar is as follows. The electron transfer capacity of iron-modified biochar is calculated based on the regression analysis results, and the linear fitting results of the calculated value and the measured value are analyzed. Among them, the established prediction model equation for the electron transfer capacity of iron-modified biochar is:

[0028] y=9.68×10 -5 +3.79×10 -6 X9-4.82×10 -6 X6-2.09×10 -6 X5, R 2 =1.0.

[0029] Where: y represents the electron transfer capacity, X5 is the percentage of C-OH content; X6 is the percentage of OC=O content; X9 is Fe 3+ (2p1 / 2) content percentage, R 2 is the goodness of fit, that is, the coefficient of certainty of the equation.

[0030] The method of the present invention is described below in conjunction with specific implementation methods.

[0031] Structural determination and ratio quantification of C, O and Fe in various iron-modified biochars

[0032] X-ray fluorescence analyzer was used to obtain the C, O and Fe structures in the iron-modified biochars, and Gaussian model was used to classify the C, O and Fe structures in the five iron-modified biochars (methods 1 to 5 in Table 1) and quantify their proportions. The percentages of C, O and Fe structures in the five iron-modified biochars are shown in Table 1.

[0033] Table 1 C, O and Fe structure ratios of five iron-modified biochars (%)

[0034]

[0035] Determination of the electron transfer capacity of five iron-modified biochars

[0036] 0.01 g of iron-modified biochar that passed through a 200-mesh sieve was placed in a sample bottle containing 20 mL of deionized water. After nitrogen blowing for 30 min, it was evenly dispersed in the aqueous phase by ultrasound for 1 h. The reaction system included an electrochemical workstation and a three-electrode system. The Ag / AgCl electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. After the mediator was added and stabilized, the electron transfer capacity of the five iron-modified biochars was measured. The results of the electron transfer capacity of the five iron-modified biochars were 2.58×10 -5 , 6.32×10 -5 , 9.27×10 -5 , 0.036×10 -5 , 0.037×10 -5 μmol e - / (g C).

[0037] Establishment of a predictive model for the electron transfer capacity of iron-modified biochar

[0038] -C=C / CC, COC / C-OH, O=C-OH, C=O, C-OH, OC=O, maghemite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2) and Fe2p1 / 2 ratio were used as independent variables to construct a stepwise regression model, and insignificant items (p>0.05) were eliminated to predict the electron transfer capacity of iron-modified biochar. The specific symbols of the constructed model are shown in Table 2.

[0039] Table 2 Relevant information of each item in the equation

[0040] name Representative symbol -C=C / CC X1 COC / C-OH X2 O=C-OH X3 C=O X4 C-OH X5 OC=O X6 Maghemite Fe(III) X7 Fe2p3 / 2 X8 <![CDATA[Fe 3+ (2p1 / 2)]]> X9 Fe2p1 / 2 X10

[0041] The constructed prediction model equation is as follows: the electron transfer capacity of iron-modified biochar is calculated based on the regression analysis results, and the fitting results between the predicted value and the actual value are analyzed ( Figure 2 ) and established a method to predict the electron transfer capacity of iron-modified biochar based on the C, O and Fe structures.

[0042] The prediction model for the electron transfer capacity of iron-modified biochar is:

[0043] y=9.68×10 -5 +3.79×10 -6 X9-4.82×10 -6 X6-2.09×10 -6 X5, R 2 =1.0.

[0044] Where: X5 is the percentage of C-OH; X6 is the percentage of OC=O; X9 is Fe 3+ (2p1 / 2) percent.

[0045] Validation of a prediction model for the electron transfer capacity of iron-modified biochar

[0046] The iron-modified biochars prepared by Fe(III) ball milling, Fe2O3 carbon thermal reduction and ZVI hydrothermal carbonization were prepared. The C, O and Fe structures were determined by XPS. The X5 (C-OH) ratios were 32.56%, 22.30% and 15.69% respectively; the X6 (OC=O) ratios were 32.03%, 36.34% and 61.95% respectively; the X9 (Fe 3+ (2p1 / 2)) percentages were 45.23%, 33.80% and 69.83% respectively. Subsequently, the model y=9.68×10 -5 +3.79×10 - 6 X9-4.82×10 -6 X6-2.09×10 -6 The electron transfer energies of the three iron-modified biochars predicted by X5 were 4.57×10 -5 , 0.31×10 -5 , 3.50×10 -5 μmol e - / (g C), the experimental value of the electron transfer capacity of iron-modified biochar was linearly fitted with the predicted value ( Figure 3 ), fitting result: y = 1.0156x - 0.01812, (R 2 =0.98) proves that this model has a good predictive effect on the electron transfer capacity of iron-modified biochar.

[0047] The above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify or improve the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein by equivalents; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for predicting the electron transfer capacity of iron-modified biochar, characterized in that: The following steps are involved: S1. Determination of C, O and Fe structures in iron-modified biochar; S2. The C, O and Fe structures in the iron-modified biochar were classified and their proportions were quantified using a Gaussian model, wherein the C structures included -C=C / CC, COC / C-OH, O=C-OH, the O structures included C=O, C-OH, OC=O, and the Fe structures included hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2), Fe2p1 / 2; S3. Determining the electron transfer capacity of the iron-modified biochar; S4. Establish a prediction model for the electron transfer capacity of iron-modified biochar to predict the electron transfer capacity of the iron-modified biochar, wherein the structure ratios of C, O and Fe are used as dependent variables, and -C=C / CC, COC / C-OH, O=C-OH, C=O, C-OH, OC=O, hematite Fe(III), Fe2p3 / 2, Fe 3+ (2p1 / 2) and Fe2p1 / 2 ratio were used as independent variables for regression analysis, and a stepwise regression model was constructed. After eliminating insignificant items with p>0.05, the optimal model was obtained: y=9.68×10 -5 +3.79×10 -6 X9-4.82×10 -6 X6-2.09×10 -6 X5,R 2 =1.0, Among them: X5 is the percentage of C-OH content, X6 is the percentage of OC=O content, X9 is the percentage of Fe 3+ (2p1 / 2) content percentage, R 2 is the goodness of fit, that is, the coefficient of certainty of the equation.

2. The method for predicting the electron transfer capacity of iron-modified biochar according to claim 1, characterized in that: In step S1, an X-ray fluorescence analyzer is used to obtain the C, O and Fe structures in the iron-modified biochar.

3. The method for predicting the electron transfer capacity of iron-modified biochar according to claim 1, characterized in that: In step S3, the electron transfer capacity of the iron-modified biochar is measured by a redox method, wherein the reaction system used in the redox method includes an electrochemical workstation and a three-electrode system, an Ag / AgCl electrode is used as a reference electrode, and a platinum sheet electrode is used as a counter electrode.

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