Method for predicting reaction characteristics of amorphous material and organic molecules and application

Abstract

The invention discloses a method for predicting reaction characteristics of an amorphous material and organic molecules, and belongs to the technical field of material modeling. The invention provides a method for predicting interaction strength of floc generated in an electric flocculation process and peracetic acid and structural evolution after combination, the method is characterized in that molecular dynamics is calculated on the basis of a first principle, interaction between the floc and organic molecules is simulated, and the floc and the organic molecules are simulated through a Vienna de novo simulation software package (Vienna de novo simulation software package). The invention relates to a VASP simulated floc and organic molecular structure model. The adsorption energy, the transition state and the like in the reaction process are obtained through precise thermodynamic calculation simulation of the first principle, and a theoretical basis and a guiding basis are provided for exploring the reaction mechanism and the process treatment performance between the electric flocculation floc or other amorphous materials and the organic matter in actual engineering application.

Description

Technical Field

[0001] The invention relates to the technical field of material modeling or sewage treatment, and in particular to a method for predicting reaction characteristics between an amorphous material and an organic molecule and its application. Background Art

[0002] Amorphous materials refer to some materials with non-complete crystalline structures or some amorphous solid materials. In the field of materials, many substances that can form crystals exist in amorphous states. Amorphous materials have unique structural characteristics, which are conducive to the diffusion of some ions and small molecules. Therefore, the reactivity of such materials is generally better than that of crystals of the same substance.

[0003] Based on the electrochemical field, the electrocoagulation process will produce a certain amount of flocs under the action of electrolysis. The flocs produced contain a variety of complex components and are also a type of amorphous material. Based on its composition, it is speculated that this type of material may have high reactivity in some specific reaction processes. However, due to its complex composition, there is currently a lack of research on its specific reaction mechanism or reactivity from the perspective of molecular modeling, so research in this area needs to be further deepened. Since theoretical calculations can quickly and accurately simulate the changes in the reaction process between various materials and organic molecules, and deepen the mechanism explanation and property prediction in the reaction process, it is expected to provide an effective basis for the prediction of the reaction characteristics of amorphous materials and conduct theoretical evaluation of process performance in actual engineering.

[0004] The flocs produced by the electroflocculation process are difficult to model due to their complex composition, so it is necessary to select a reasonable simplified model to study them, explore and predict the interfacial active sites and reaction characteristics between the floc components and organic molecules, and determine the types of active free radicals produced in the process based on the structural modeling prediction results, and determine the pollutant treatment performance of the active free radicals produced by the electroflocculation catalytic activation process on sewage treatment plants or other water treatment processes. Therefore, developing an effective method to simulate the reaction characteristics of amorphous materials and organic molecules is crucial for in-depth exploration of their reaction characteristics. Summary of the invention

[0005] The purpose of the present invention is to provide an effective method for simulating the reaction characteristics of amorphous materials and organic molecules from the perspective of molecular modeling, in order to solve the problems of unclear reaction mechanism between floc components and organic molecules generated in the existing electroflocculation process, and complex model building of materials with complex components. The method is based on molecular dynamics calculated by first principles, simulates the interface interaction between floc components and organic molecules, obtains the strength of the reaction between floc components and organic molecules, as well as the structural evolution and energy change, etc., and provides a guiding basis for the exploration of the mechanism of interaction between actual complex materials and organic molecules. It provides an effective means to clarify the active sites on the surface of organic molecules and flocs, the formation of active free radicals, and the structural transformation trend after the reaction, and provides a theoretical basis and guidance for exploring the reaction mechanism between electroflocculation flocs or other amorphous materials and organic matter and the pollutant control capacity in actual engineering applications.

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions: A method for predicting the reaction characteristics of an amorphous material with an organic molecule comprises the following steps: S1, Characterization of floc composition: Firstly, flocs are prepared by electro-flocculation reaction under direct current power supply, and flocs are amorphous materials. Then, the flocs are characterized and the effective components of the flocs and the proportion of each effective component are analyzed. S2, construction of structural model: According to the material characterization results, effective components are selected for simulation analysis. Molecular modeling software is used to construct structural models for the selected effective components and the organic molecules to be explored, and the structural models are optimized. S3, reaction characteristics prediction: After the modeling is completed, the strength of the interaction between amorphous materials and organic matter is preliminarily determined by calculating the adsorption energy between each effective component and the organic matter.

[0007] As a preferred experimental scheme of the present invention, the effective components of the amorphous material can include but are not limited to iron, aluminum, copper or their alloys, etc., and various iron, aluminum, copper oxides or their composite materials, etc., produced according to the anode electrode materials used in the electrocoagulation process.

[0008] As a preferred experimental scheme of the present invention, the anode used in the electrocoagulation reaction process is Taking an iron electrode or an iron-containing electrode material as an example, the amorphous material is a flocculent precipitate generated during the electro-flocculation process, namely, various iron-containing oxides.

[0009] As a preferred experimental scheme of the present invention, the effective ingredients contained in the amorphous material include Fe(OH)2, Fe(OH)3, FeOOH and the like.

[0010] As a preferred experimental scheme of the present invention, in step S2, the specific modeling construction includes the following steps: S21, using molecular modeling software, respectively modeling the above effective components and performing cell expansion processing on the original unit cell; S22, perform first-principles optimization on each crystal to obtain a reasonable unit cell structure, then perform cell cutting to obtain a surface model of the corresponding index surface, set a vacuum layer, optimize the atomic position, and then perform first-principles optimization to obtain a surface model of the crystal material.

[0011] In step S22, the first principle optimization is: using the VASP software package and setting the accuracy to high-precision first principle calculation.

[0012] As a preferred experimental scheme of the present invention, the prediction of reaction characteristics is based on calculating the adsorption energy between each effective component and the organic matter to preliminarily judge and predict the reaction characteristics and the strength of the interaction between the material and the organic matter.

[0013] As a preferred experimental scheme of the present invention, the adsorption energy calculation uses a plane wave basis set, the pseudopotential adopts the projected augmented plane wave (PAW) method, the Perdew-Burke-Ernzerh (PBE) in the generalized gradient approximation is used to describe the exchange-correlation functional, the plane wave cutoff energy is set to 400 eV, and the K-point grid distribution in the first Brillouin zone is set to 1×1×1 using the Monkhorst-Pack method.

[0014] As a preferred experimental scheme of the present invention, the structural optimization of the adsorption energy calculation surface model is based on the energy minimization principle. For the sake of preliminary screening, the self-consistent energy convergence standard is 10 -5 eV, and the force convergence criterion was 0.02 eV / Å.

[0015] As a preferred experimental scheme of the present invention, the components in the flocs that interact strongly with organic matter are determined based on the adsorption energy calculation results, and transition state analysis is performed to determine and predict the energy changes and structural evolution during the interaction process.

[0016] As a preferred experimental scheme of the present invention, the energy of the transition state includes but is not limited to: at least one of the internal energy of the molecule, the total energy of the electron, the potential energy of the electron, and the Gibbs free energy of the molecule.

[0017] The present invention claims protection for a specific application, which is the selection of anode materials and external catalysts or activators for electroflocculation treatment of sewage. According to the method of the present invention, the reaction characteristics of different anode materials used in the electroflocculation process or flocs of complex components generated under specific reaction conditions with external catalysts or activators are predicted. When the flocs have a strong interface interaction with the catalyst or treatment agent and produce active species that may be beneficial to the degradation of pollutants without the generation of obvious toxic by-products, the corresponding anode materials and treatment agents or activators are selected for electroflocculation treatment of sewage, thereby improving the efficiency and capacity of sewage treatment.

[0018] The beneficial effects of the present invention are as follows: the present invention targets the floc components with relatively complex components generated during the electro-flocculation process, selects a reasonable model simplification method to build and optimize the model of the effective components in the flocs, adopts the first principles to simulate the reaction characteristics between the floc components and organic matter, and further explores the specific reaction mechanism, structural evolution, energy change, etc., to provide a theoretical basis and guiding basis for exploring the reaction characteristics between the floc components with complex components and other possible amorphous materials and organic matter.

[0019] The method of the invention can be used for the selection of anode materials and external catalysts or activators when treating sewage by electro-flocculation, and can improve the efficiency of treating sewage by electro-flocculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structural model of optimized Fe(OH)2 and PAA; Figure 2 Schematic diagram of the structural model of optimized Fe(OH)3 and PAA; Figure 3 Schematic diagram of the structural model of optimized FeOOH and PAA; Figure 4 The structural evolution diagrams of Fe(OH)2 before and after the interaction with PAA, IS (a), TS (b), FS (c), where IS is the initial structure, TS is the transition structure, and FS is the final structure; Figure 5 It is the transition state diagram before and after the interaction between Fe(OH)2 and PAA; Figure 6 Schematic diagram of the interaction between Fe(OH)2 and PAA. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical methods and advantages of the embodiments of the present invention clearer, the technical methods in the embodiments of the present invention will be clearly described below in combination with the specific embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention. Based on the specific embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0022] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0023] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts the conventional purity used in the art.

[0024] There is no particular limitation on the experimental devices used in the present invention, and all commonly used experimental devices in the art are adopted.

[0025] Example 1 A method for predicting the reaction characteristics of an amorphous material with an organic molecule comprises the following steps: Firstly, flocs were prepared by electro-flocculation reaction under direct current power supply, and the flocs produced by the electro-flocculation process were characterized. The phase composition and proportion of each component of the flocs were analyzed, and effective components were selected from the flocs for simulation analysis based on the characterization results. Using molecular modeling software, the structural models of the selected effective components and the organic molecules to be explored were constructed and optimized. The schematic diagrams of the optimized structures of Fe(OH)2 and PAA are shown in the figure. Figure 1 As shown; After the modeling is completed, the reaction characteristics and interaction strength between Fe(OH)2 and PAA are preliminarily determined by calculating the adsorption energy between Fe(OH)2 and PAA; The schematic diagram of the optimized structure of Fe(OH)3 and PAA is shown in Figure 2 As shown; After the modeling is completed, the reaction characteristics and interaction strength between Fe(OH)3 and PAA are preliminarily determined by calculating the adsorption energy between Fe(OH)3 and PAA; The structural diagram of the optimized FeOOH and PAA is shown in Figure 3 As shown; After the modeling is completed, the reaction characteristics and interaction strength between FeOOH and PAA are preliminarily determined by calculating the adsorption energy between FeOOH and PAA; Among them, the anode used in the electro-flocculation reaction device is an iron electrode or an iron-containing electrode material.

[0026] The electro-flocculation reaction device is made of organic glass or quartz glass and has a cylindrical or rectangular shape.

[0027] The electrode plates are arranged in parallel.

[0028] Among them, the current intensity of the electric flocculation reaction device is 0.001~1A.

[0029] Among them, the electrolyte solution is 50mM Na2SO4.

[0030] Example 2 According to the adsorption energy calculation results in Example 1, the strength of the interaction between each floc component produced during the electroflocculation process and PAA was predicted, and effective components were selected for simulation, and energy calculation was performed based on the first principles. According to the calculation results, the transition state structure simulation was performed to obtain the energy of the reaction intermediate, the transition state energy and the reaction energy barrier. Figure 4 The figure shows the structural evolution of Fe(OH)2 in the flocs produced by the electroflocculation process before and after the interaction with PAA. Figure 4 (a) is the initial structure, Figure 4 (b) is transition structure, Figure 4 (c) is the final structure. The structural evolution results show that after PAA interacts with the floc surface, the OO bond in the PAA molecule breaks, and the oxygen atom in the hydroxyl group further combines with the iron atom in the metal oxide to form a stronger bond. This process change can be judged that electron transfer occurs between the organic molecule and the floc, further promoting • OH, CH3C(O)O • 、 CH3C(O)OO • The formation of reactive free radical species (such as Figure 6 ), thereby promoting the degradation of pollutants in water, proving the superiority of this catalytic activation process and its potential value in practical process applications.

[0031] Example 3 According to the adsorption energy calculation results in Example 1, the strength of the interaction between each floc component produced during the electroflocculation process and PAA is predicted, and energy calculation is performed based on the first principle. The transition state is deduced based on the calculation results to obtain the energy of the reaction intermediate, the transition state energy and the reaction energy barrier. Figure 5 Shown is the transition state diagram before and after the interaction between Fe(OH)2 and PAA in the floc component produced by the electroflocculation process. Figure 5The results show the active sites of the interaction between PAA and the flocculent interface, and the breaking of the OO bond in the PAA molecule during the transformation from the transition state structure to the final state structure is a transition from high to low energy. This process can occur spontaneously, which is more conducive to the generation of active free radicals with strong oxidizing ability for pollutants in water. It confirms the prospect of this technology in sewage purification from a theoretical level, provides scientific and rapid molecular theoretical level simulation for the implementation of the project, and verifies the feasibility of the process.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for predicting the reaction characteristics of amorphous materials and organic molecules, characterized in that: The following steps are involved: S1, Preparation and characterization of amorphous materials: Firstly, flocs are prepared by electro-flocculation reaction under direct current power supply, and flocs are amorphous materials. Then, the flocs are characterized and the effective components of the flocs and the proportion of each effective component are analyzed. S2, construction of structural model: According to the material characterization results, effective components are selected for simulation analysis. Molecular modeling software is used to construct structural models for the selected effective components and the organic molecules to be explored, and the structural models are optimized. S3, reaction characteristics prediction: After the modeling is completed, the strength of the interaction between amorphous materials and organic matter is preliminarily determined by calculating the adsorption energy between each effective component and the organic matter.

2. A method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: The anode material of the electro-flocculation reaction in step S1 is iron, aluminum, copper or their alloys, and the amorphous material is iron oxide, aluminum oxide, copper oxide or their composite materials.

3. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: The anode material of the electro-flocculation reaction in step S1 is iron, and the amorphous material is iron oxide, and the effective components contained therein include Fe(OH)2, Fe(OH)3, and FeOOH.

4. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: In step S2, the construction of the structural model includes the following steps: S21 Using molecular modeling software, model the above effective components respectively and perform cell expansion processing on the original unit cell; S22 performs first-principles optimization on each crystal to obtain a reasonable unit cell structure, and then performs cell cutting to obtain the surface model of the corresponding index surface. A vacuum layer is set to optimize the atomic position, and then first-principles optimization is performed to obtain the surface model of the crystal material.

5. A method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 4, characterized in that: In step S22, the first principle optimization is: using the VASP software package and setting the accuracy to high-precision first principle calculation.

6. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: By calculating the adsorption energy between each effective component and organic matter, the reaction characteristics and interaction strength between amorphous materials and organic matter can be preliminarily judged and predicted.

7. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: The adsorption energy was calculated using a plane wave basis set, the projected augmented plane wave method was used for the pseudopotential, the Perdew-Burke-Ernzerh in the generalized gradient approximation was used to describe the exchange-correlation functional, the plane wave cutoff energy was set to 400 eV, and the K-point grid distribution in the first Brillouin zone was set to 1×1×1 using the Monkhorst-Pack method.

8. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: The structural optimization of the surface model is based on the principle of energy minimization. For the sake of preliminary screening, the self-consistent energy convergence criterion is 10 -5 eV, and the force convergence criterion was 0.02 eV / Å.

9. The method for predicting the reaction characteristics of amorphous materials and organic molecules according to claim 1, characterized in that: The components in the flocs that interact strongly with organic matter are determined based on the adsorption energy calculation results, and a transition state analysis is performed to determine and predict the energy changes and structural evolution during the interaction process.

10. An application for predicting the reaction characteristics of amorphous materials and organic molecules, characterized in that: Selection of anode materials and external catalysts or activators for electroflocculation treatment of sewage. According to the method of any one of claims 1 to 9, the reaction characteristics of different anode materials used in the electroflocculation process or flocs of complex components generated under specific reaction conditions with external catalysts or activators are predicted. When the flocs have strong interfacial interactions with the catalyst or treatment agent and produce active species that may be beneficial to the degradation of pollutants without the generation of obvious toxic by-products, the corresponding anode materials and treatment agents or activators are selected for electroflocculation treatment of sewage to improve the efficiency and capacity of sewage treatment.

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