Design method of environment-friendly activated carbon modified amine impregnation liquid for efficiently removing formaldehyde

Abstract

The invention belongs to the field of modified activated carbon, and particularly relates to a design method of environment-friendly activated carbon modified amine impregnation liquid for efficiently removing formaldehyde. The design method comprises the following steps: constructing a group library of an impregnation liquid molecular structure; constructing a molecular structure and a property constraint condition of the steeping liquor molecular structure model; constructing a relational expression of the equilibrium adsorption capacity of the impregnation liquid molecules adsorbed on the activated carbon and a relational expression of the theoretical formaldehyde removal capacity of the modified activated carbon obtained after the impregnation liquid molecules are modified; gAMS software is adopted as analog calculation and impregnation liquid molecules are determined. According to the method disclosed by the invention, when the molecular structure and the property constraint condition are designed, the safety and the environmental performance of molecules of the impregnation liquid are considered, so that the obtained impregnation liquid has good safety and environmental properties, the prepared modified activated carbon has excellent formaldehyde removal performance, and the workload of screening the impregnation liquid in a traditional test is reduced.

Description

Technical Field

[0001] This invention belongs to the field of modified activated carbon, specifically relating to the design method of an environmentally friendly activated carbon high-efficiency formaldehyde removal modified amine impregnation solution. Background Technology

[0002] Formaldehyde has become the most significant indoor air pollutant due to its wide availability, simple release conditions, long release period, and high level of harm to the human body. Formaldehyde is highly toxic. Its acute toxicity generally occurs when the human body is exposed to high concentrations of formaldehyde in the air, causing eye irritation, tearing, dermatitis, coughing, and other symptoms through direct contact with the skin. However, if formaldehyde is inhaled chronically and enters the bloodstream through the respiratory tract, it reacts with nucleic acids and proteins to form unstable compounds, leading not only to chronic respiratory diseases but also to symptoms of poisoning such as headaches, dizziness, and anxiety. Inhalation of high concentrations of formaldehyde (>60 mg / m³) can cause serious health problems. 3 Formaldehyde can cause pneumonia and pulmonary edema, and in severe cases, it can even be life-threatening. Currently, there are many types of indoor formaldehyde purification technologies. Due to its economic efficiency, ease of operation, environmental friendliness, and lack of secondary pollution, adsorbent adsorption technology has become one of the main methods for purifying indoor formaldehyde.

[0003] When activated carbon is used as an adsorbent to adsorb formaldehyde, physical adsorption dominates. Physical adsorption is reversible but lacks selectivity and cannot directionally adsorb formaldehyde. Furthermore, activated carbon is a non-polar adsorbent, which limits its formaldehyde adsorption capacity. Surface modification of activated carbon, introducing active components into its surface and pores, can significantly enhance its formaldehyde adsorption capacity. Liquid-phase impregnation is an effective and convenient method for activated carbon modification. By selecting a specific modification solvent for the target pollutant formaldehyde and impregnating it to load the effective components of the solvent onto the activated carbon, the adsorption capacity of the modified activated carbon for formaldehyde can be significantly improved compared to the original activated carbon.

[0004] Amines and formaldehyde can undergo a condensation reaction to form methyleneamine; therefore, amine impregnation solutions are often used to modify activated carbon to enhance its formaldehyde removal performance. Traditional activated carbon modification solvents are subject to strict restrictions during storage and use due to their irritant properties, chronic toxicity, and flammability, and the formaldehyde removal capacity of activated carbon modified with them still has room for improvement. How to obtain an impregnation solution that meets production requirements and can modify activated carbon to achieve efficient formaldehyde removal has become a key research issue. Traditional trial-and-error methods for screening impregnation solutions result in high production costs and long experimental cycles. Reducing the workload, cost, and cycle time of experimental screening is also one of the main current research requirements. Summary of the Invention

[0005] To address the problems of the large workload involved in the research and development of impregnation solutions for improving the methanol removal efficiency of activated carbon, and the poor performance of existing modified activated carbon impregnation solutions, this invention will provide a design method for an environmentally friendly, high-efficiency formaldehyde removal modified impregnation solution for activated carbon.

[0006] To achieve the above objectives, the following technical solutions are specifically included: On one hand, the present invention provides a method for designing impregnation liquid molecules, comprising the following steps: S1. Constructing a group library for the molecular structure of the impregnation solution; S2. Molecular structure and property constraints for constructing the molecular structure model of the impregnation solution; S3. Construct the relationship between the equilibrium adsorption amount of impregnation liquid molecules on activated carbon and the relationship between the theoretical formaldehyde removal capacity of the modified activated carbon obtained after the impregnation liquid molecules are modified. S4. Use GAMS software for simulation calculation and determine the molecules of the impregnation liquid; the calculation process specifically includes the following steps: construct a molecular library of molecular structure models of the impregnation liquid based on the molecular structure and property constraints described in step S2; then determine the molecular structure of the impregnation liquid from the molecular library based on the relationship of equilibrium adsorption amount described in step S3 and the relationship of the theoretical formaldehyde removal capacity of modified activated carbon.

[0007] In the design method of the impregnation liquid of the present invention, a group library and molecular structure and property constraints of the impregnation liquid molecular structure model are first constructed. Then, the effect of the impregnation liquid is evaluated based on the relationship between the equilibrium adsorption amount of the impregnation liquid molecular structure on activated carbon obtained from the above constraints and the theoretical formaldehyde removal capacity of the activated carbon after the impregnation liquid molecules are modified. The present invention has achieved a comprehensive evaluation of the degree of modification of activated carbon and the formaldehyde removal capacity of the modified activated carbon when designing the impregnation liquid molecular structure. This is conducive to scientifically and efficiently obtaining the actual needs of the impregnation liquid for activated carbon modification that meets the requirements of high-efficiency formaldehyde removal. It can overcome the defects of long cycle, low efficiency and high cost of traditional trial and error method for screening and designing impregnation liquid molecules.

[0008] In a preferred embodiment of the present invention, in step S1, the functional group library of the impregnation liquid molecular structure includes amine groups. Amino solvents, after modifying activated carbon, are more effective at removing methanol molecules. The present invention employs a group contribution method to decompose the commonly used amine impregnation liquid molecular structure into group combinations and establish a functional group library for impregnation liquid molecular design, using amine groups as essential functional groups. This can increase the probability of obtaining a highly efficient methanol-removing impregnation liquid from the modified activated carbon.

[0009] In a preferred embodiment of the present invention, in step S1, the group library of the impregnation liquid molecular structure is constructed by the group contribution method.

[0010] In a preferred embodiment of the present invention, in step S1, the group library of the impregnation liquid molecular structure includes a main chain group set, a functional group set, a chain-terminal group set, a non-chain-terminal group set, an aromatic group set, and a group set containing carbon-carbon double bonds.

[0011] In a preferred embodiment of the present invention, in step S2, the molecular structure and property constraints include at least one of the following terms: (a) The constraint equation for the molecular structure being limited to one of the following: acyclic, monocyclic, or bicyclic molecules is: (1), Among them, the binary variable y a y m 、 and y b These indicate whether the three structures of acyclic, monocyclic, or bicyclic molecules exist in the designed molecule, respectively. (b) The constraint equations for molecules with a valence of 0 and where no more than one bond can be connected between any two adjacent groups are as follows: (2), (3); Equation 2 is the molecular structure constraint equation, and Equation 3 is the molecular connection mode constraint equation, N k and ν k These are the number of groups k in the molecule and their valence, respectively. (c) The constraint equations imposed on the number of aromatic and non-aromatic groups and the manner in which they are connected include: (4), (5); Equation 4 is the number constraint equation for aromatic and non-aromatic groups, and Equation 5 is the connection mode constraint equation for aromatic and non-aromatic groups. Ar N represents a collection of aromatic groups. ac It is the number of aromatic rings in the molecule; This represents the set of non-aromatic groups with a valence greater than or equal to 3. This represents the set of aromatic groups with a valence greater than or equal to 3, where AR and NAR represent aromatic and non-aromatic groups, respectively. The valence of group k is m = y. a -y b y a and y b It is a binary variable. When the value of m is -1, 0 or 1, it represents that the molecular structure is a bicyclic molecule, a monocyclic molecule or an acyclic molecule, respectively. (d) The constraint equation for the number of double bond groups in the molecule is shown in Equation 6: (6); Among them, G D This represents a set of groups containing carbon-carbon double bonds; (e) The quantity restriction equations for various types of functional groups include: (7), (8); where Equation 7 is the constraint equation for the number of main chain groups in the molecule, and Equation 8 is the constraint equation for the number of functional groups in the molecule, G M G represents the set of main chain groups. F Represented as a set of functional groups, N max This indicates the maximum number of functional groups in a molecule; (f) The melting and boiling points of the impregnation solution molecules must ensure that the impregnation solution is liquid at room temperature and pressure to meet the impregnation requirements. The constraint equation for this property is: (9), (10); Equation 9 is the molecular melting point constraint equation, and Equation 10 is the molecular boiling point constraint equation. m,k and T b,k These are the contributions of group k to the melting and boiling points of the molecule in the group contribution method; T m,0 and T b,0 These are constants in the model for estimating the melting and boiling points of the impregnating solution molecules; T m,max and T b,min These represent the maximum value of the melting point of the impregnating liquid molecules and the minimum value of the boiling point of the molecules, respectively; (g) The constraint equation for the flash point of the molecule is as follows: Equation 11: (11), Among them, F p,k F is the contribution of group k to the molecular flash point in the group contribution method. p,min It is the minimum flash point of the impregnating liquid molecules required by the design; (h) The constraint equations for the aquatic biotoxicity of molecules, soil enrichment coefficients, and environmental properties of bioconcentration factors include: (12), (13) (14); Wherein, Equation 12 is the constraint equation for molecular aquatic biotoxicity, Equation 13 is the constraint equation for molecular soil enrichment coefficient, and Equation 14 is the constraint equation for molecular bioconcentration factor. LC k K ow and BCFk These are the contributions of group k to the aquatic biotoxicity of the impregnating solution molecules, the soil enrichment coefficient, and the bioconcentration factor, respectively; LC max K oc,max and BCF max These are the maximum values ​​of the molecular aquatic organism toxicity concentration, soil enrichment coefficient, and bioconcentration factor of the designed impregnation solution; (e) The constraint equation for the number of amine groups in the molecule is as follows: Equation 15: (15); Where, N 25 N 27 N 28 and N 29 These represent the number of amino groups 25, 27, 28, and 29, respectively. 25, 27, 28, and 29 are the numbers of ACNH2 group, CH2NH2 group, CH3NH group, and CH2NH group, respectively.

[0012] This invention utilizes the group contribution method to transform molecular properties into combinations of group contributions. Regardless of the molecule's structure, the contribution value of a single group to the molecular property remains unchanged, making it possible to rapidly predict the properties of a large number of molecules. The method designed in this invention can shorten the experimental time required for selecting impregnating solutions, and the obtained impregnating solutions possess good safety and environmental properties. The prepared modified activated carbon exhibits excellent formaldehyde removal performance, reducing the workload of traditional impregnating solution screening.

[0013] Furthermore, as can be seen from the constraints in section ag, this invention constrains the types, numbers, and structural complexity of the functional groups constituting the impregnation solution molecular structure during its design. This ensures that the designed molecular structure is reasonable, real, and achievable, facilitating its practical application in industrial production. From the constraints in section h regarding environmental properties, it is clear that the design of the impregnation solution molecules has taken into account their effects on aquatic organism toxicity, soil enrichment, and bioconcentration, ensuring that the molecular properties meet both environmental friendliness and formaldehyde removal performance requirements.

[0014] In a preferred embodiment of the present invention, in step S3, the relationship of the equilibrium adsorption amount includes the following formula 16: (16); in, and They are components i Mole fraction in bulk phase and adsorbed solid solution; and The components are respectively i Activity coefficient in bulk phase and adsorbed solid solution; It is the difference in chemical potential between the wetted adsorbent before adsorption and after adsorption of component i. T , R and These are adsorption temperature, ideal gas constant, and composition. i Surface phase capacity.

[0015] In a preferred embodiment of the present invention, in step S3, the theoretical formaldehyde removal capacity of the modified activated carbon is expressed as shown in Formula 17: (17); in, It is the saturation adsorption capacity of activated carbon for adsorbing molecules. It refers to the quality of activated carbon; N 25 N 27 N 28 and N 29 These represent the number of amino groups 25, 27, 28, and 29, respectively. 25, 27, 28, and 29 are the numbers of ACNH2 group, CH2NH2 group, CH3NH group, and CH2NH group, respectively.

[0016] In Equation 16 above, the ASST theory is used to calculate the loading of impregnation liquid molecules on activated carbon. Then, Equation 17 is used to evaluate the formaldehyde removal performance of the modified activated carbon after different impregnation liquid designs are used to modify the activated carbon, and the amine impregnation liquid with the best performance is screened out.

[0017] In a preferred embodiment of the present invention, step S4 of the calculation process further includes the following steps: defining sets, parameters, variables and equations in the software.

[0018] More preferably, the set includes set K, set U and set P, the elements in set K are the groups in the group library, the elements in set U are the contribution values ​​of each group to different properties of the molecule, and the elements in set P are the types of different groups.

[0019] More preferably, the variables include the types of various groups that make up the impregnation liquid molecules and the number of each group.

[0020] More preferably, the equation includes the constraint equation among the molecular structure and property constraints, the relationship of the equilibrium adsorption amount, and the relationship of the theoretical formaldehyde removal capacity of the modified activated carbon. The design method of this invention reduces the experimental time consumed by traditional impregnation solution design methods, and conveniently and quickly designs novel modified impregnation solution components that enhance the formaldehyde removal performance of activated carbon. The modified activated carbon prepared by the impregnation solution designed by this invention has a strong formaldehyde purification capacity. Simultaneously, due to the property constraints of molecular design, safety hazards and environmental pollution during the production process are reduced, achieving efficient and clean production.

[0021] On the other hand, the present invention provides a method for preparing modified activated carbon, comprising the following steps: Modified activated carbon is obtained by sequentially mixing and impregnating activated carbon with an impregnation solution, followed by filtration and drying. The impregnation solution is triethylenetetramine.

[0022] In a preferred embodiment of the present invention, the impregnation reaction is carried out in a constant temperature water bath shaker, and the shaker oscillates at a speed of 50-300 r / min.

[0023] In a preferred embodiment of the present invention, the drying temperature is 60-100℃ and the drying time is 24-48 hours.

[0024] Compared with existing technologies, this invention has the following advantages: This invention belongs to the field of modified activated carbon, specifically relating to a design method for an environmentally friendly, highly efficient formaldehyde-removing modified amine impregnation solution for activated carbon. The design method of this invention includes the following steps: constructing a group library for the molecular structure of the impregnation solution; constructing molecular structure and property constraints for the molecular structure model of the impregnation solution; constructing the relationship between the equilibrium adsorption amount of the impregnation solution molecules on activated carbon and the relationship between the theoretical formaldehyde removal capacity of the modified activated carbon obtained after the impregnation solution molecules are modified; and using GAMS software for simulation calculations to determine the impregnation solution molecules. This invention's method incorporates the safety and environmental performance of the impregnation solution molecules when designing the molecular structure and property constraints, resulting in an impregnation solution with good safety and environmental properties, and enabling the prepared modified activated carbon to have excellent formaldehyde removal performance, thus reducing the workload of traditional experiments in screening impregnation solutions. Attached Figure Description

[0025] Figure 1 The results show the formaldehyde adsorption and removal performance of three unmodified activated carbon (AC) samples and three modified supported activated carbon (ACM) samples. The vertical axis of the figure represents the formaldehyde clean air delivery rate, which is defined as the volume of formaldehyde-contaminated air that the material can purify per hour. Detailed Implementation

[0026] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0027] Example 1 A method for designing an amine-based impregnation solution includes the following steps: (1) Selection and construction of a group library for the molecular structure of impregnation solutions: 166 commonly used amine impregnation solutions in industry were selected. Their molecular structures were decomposed into combinations of groups according to the group contribution method. After excluding groups that did not meet the requirements, 31 of the most common groups were selected to form a group library for molecular design. For example, the commonly used triethylenetetramine impregnation solution has the molecular formula C6H. 18 N4, with the structural formula CH2NH2CH2NHCH2CH2NHCH2CH2NH2, can be decomposed into a combination of groups such as aminomethyl (-CH2NH2), iminomethyl (-CH2NH), and methylene (-CH2-).

[0028] Among them, 166 amine impregnation solutions include those widely used in industry, such as nonanediamine, tert-butylamine, and triethylenediamine. The functional group library contains functional groups categorized into main chain groups (G...). M ), functional groups (G) F ), chain-terminal groups (G CE ), non-chain terminal groups (G NCE ), aromatic groups (G Ar ) and groups containing carbon-carbon double bonds (G D The group library is categorized into six main groups, and corresponding groups are constructed according to these categories. This can also be understood as a sub-database of group components; the group library is composed of various group sets. Specifically, in the formulas discussed in this paper, G... M G F G CE G NCE G Ar G D These represent the main chain group set, the functional group set, the chain-terminal group set, the non-chain-terminal group set, the aromatic group set, and the group set containing carbon-carbon double bonds, respectively. To meet the requirements of the target impregnation solution, it is necessary to clarify which performance indicators the impregnation solution molecules must meet, such as the physicochemical properties and environmental safety characteristics of the molecules, as well as external process conditions. In this embodiment, during the group screening process, four types of groups that clearly do not meet the requirements of the molecular design of this invention need to be excluded in advance: (1) zero-valence groups; (2) cycloalkyl groups; (3) groups with potentially negative safety and environmental characteristics; and (4) groups sensitive to high temperatures.

[0029] Thirty-one functional groups meeting the requirements were selected as candidate functional groups for the design of the impregnation solution molecular structure model. These functional groups were then classified according to the six categories mentioned above. Groups belonging to any of these six categories were represented by "1," and each functional group was assigned a number (considered a functional group ID). The classification results are shown in Table 1. For example, in Table 1 below, CH3 is functional group 1, which belongs to the main chain functional group G. M Group 15 is both a functional group G F It's the chain-terminal group G again. CE Meanwhile, "AC" in Table 1 represents a single carbon in the benzene ring, that is, the structure of a six-membered benzene ring with any one of the six vertices CH removed, or in other words, the structure of a benzene ring is C6H6 formed by six AC-H atoms.

[0030] Table 1 (2) Constructing mathematical constraint equations for the molecular structure model of the impregnation liquid: Based on the rationality of the molecular structure and the various properties that need to be satisfied in the production process, the relationship between the structure and properties of the solvent molecules is established. In this embodiment, molecular structure constraint equations and molecular property constraint equations are used to represent the relationship; in the process of establishing the above constraint equations, it is necessary to optimize the types of groups that make up the molecular structure, the number of times each group appears in the molecule, and the connection relationship between groups, and determine the specific properties of the solvent molecules through the group contribution method.

[0031] The constraints of molecular structure models in the molecular design process include: the molecular structure can only be one of acyclic, monocyclic, and bicyclic molecules; the valence of the molecule is 0 and the bonds between any two adjacent groups cannot exceed one; the number of aromatic and non-aromatic groups and the way they are connected need to be limited to avoid generating overly complex aromatic compounds; the number of double bond groups in the molecule needs to be limited to ensure the stability of the molecular structure; and the number of various types of groups needs to be limited to ensure that the generated molecules are of appropriate size, can enter the pores of activated carbon, and be adsorbed.

[0032] (a) The constraint equation for the molecular structure being limited to one of the following: acyclic, monocyclic, or bicyclic molecules is: (1), Among them, y a y m 、 and y b These are binary variables, representing the presence or absence of acyclic, monocyclic, or bicyclic structures in the designed molecule.

[0033] (b) The constraint equations for molecules with a valence of 0 and where no more than one bond can be connected between any two adjacent groups are as follows: (2), (3); Equation 2 is the molecular structure constraint equation, and Equation 3 is the molecular connection mode constraint equation, N k and ν k These are the number of groups k in the molecule and their valence, respectively.

[0034] (c) To avoid generating overly complex aromatic compounds, the limiting equations imposed on the number of aromatic and non-aromatic groups and the way they are connected include: (4), (5); Equation 4 is the number constraint equation for aromatic and non-aromatic groups, and Equation 5 is the connection mode constraint equation for aromatic and non-aromatic groups. Ar N represents a collection of aromatic groups. ac It is the number of aromatic rings in the molecule; This indicates a non-aromatic group with a valence greater than or equal to 3. This indicates an aromatic group with a valence greater than or equal to 3, where AR and NAR represent aromatic and non-aromatic groups, respectively. The valence of group k is m = y. a -y b y a and y b It is a binary variable. When the value of m is -1, 0 or 1, it represents that the molecular structure is a bicyclic molecule, a monocyclic molecule or an acyclic molecule, respectively.

[0035] (d) The constraint equation for the number of double bond groups in the molecule is shown in Equation 6: (6); Among them, G D This represents a set of groups containing carbon-carbon double bonds.

[0036] (e) The quantity restriction equations for various types of functional groups include: (7), (8); Equation 7 is the constraint equation for the number of main chain groups in the molecule, and Equation 8 is the constraint equation for the number of functional groups in the molecule. M G represents the set of main chain groups. F Represented as a set of functional groups, N max This indicates the maximum number of functional groups in a molecule.

[0037] The property constraints in the molecular design process include: the melting point, boiling point and flash point of the molecule need to be within a suitable range; the environmental properties of the molecule, such as its aquatic biotoxicity, soil enrichment coefficient and bioconcentration factor, need to be within a suitable range; to avoid negative impacts on the aquatic environment after the discharge of production waste liquid, and to ensure the formaldehyde removal performance of the modified activated carbon, the molecule must contain amine groups.

[0038] (f) The melting and boiling points of the molecules must ensure that the impregnation solution is liquid at room temperature and pressure to meet the impregnation requirements. The constraint equation for this property is: (9), (10); Equation 9 is the molecular melting point constraint equation, and Equation 10 is the molecular boiling point constraint equation. m,k and T b,k These are the contributions of group k to the melting and boiling points of the molecule in the group contribution method; T m,0 and T b,0 These are the adjustable parameters or general constants in the melting and boiling point estimation model; T m,max and T b,min These represent the maximum value of the melting point of the solvent (impregnation liquid) molecule and the minimum value of the boiling point of the molecule, respectively.

[0039] (g) The constraint equation for the flash point of the molecule is as follows: Equation 11: (11), Among them, F p,k F is the contribution of group k to the molecular flash point in the group contribution method. p,min It is the minimum flash point of the solvent (impregnation liquid) molecules required by the design.

[0040] (h) The constraint equations for environmental properties such as molecular biotoxicity, soil enrichment coefficient, and bioconcentration factor include: (12), (13) (14); Wherein, Equation 12 is the constraint equation for molecular aquatic organism toxicity, Equation 13 is the constraint equation for molecular soil enrichment coefficient, and Equation 14 is the constraint equation for molecular bioconcentration factor. LC k K ow and BCF k These represent the contributions of group k to the aquatic biotoxicity of the solvent (impregnation solution), soil enrichment coefficient, and bioconcentration factor, respectively. LC max K oc,max and BCF maxThese are the maximum values ​​of the aquatic organism toxicity concentration of the designed solvent (impregnation solution), the soil enrichment coefficient, and the bioconcentration factor.

[0041] Meanwhile, the constraint equation for the number of amine groups in the molecule is as follows: Equation 15: (15); Where, N 25 N 27 N 28 and N 29 The numbers represent the number of amino groups 25, 27, 28, and 29, respectively, as shown in Table 1.

[0042] (3) Establish the equilibrium adsorption capacity relationship between the modified activated carbon and the impregnation liquid molecules, and the formaldehyde removal performance relationship of the modified activated carbon based on the designed impregnation liquid molecules.

[0043] Using the Adsorbate-Solid-Solution Theory (ASST) and the Universal Functional Group Activity Coefficient Model (UNIFAC), the equilibrium adsorption capacity of the designed impregnation solution molecules on activated carbon was calculated based on the phase equilibrium relationships of each component at adsorption equilibrium. The phase equilibrium relationships between the components at adsorption equilibrium are shown in Equation 16. (16); in, and The components are respectively i Mole fraction in bulk phase and adsorbed solid solution; and The components are respectively i Activity coefficient in bulk phase and adsorbed solid solution; It is the difference in chemical potential between the wetted adsorbent before adsorption and after adsorption of component i. T , R and These are adsorption temperature, ideal gas constant, and composition. i Surface phase capacity.

[0044] The formaldehyde removal capacity of each candidate molecule was determined by combining the reaction mechanism of amine molecules with formaldehyde and the equilibrium adsorption capacity on activated carbon. The formula for calculating the formaldehyde removal performance of activated carbon after impregnation molecule modification is shown in Equation 17 below: (17); in, It is the saturation adsorption capacity of activated carbon for adsorbing molecules. It refers to the quality of the activated carbon.

[0045] (4) Construct a molecular structure model of the impregnation solution, and screen and determine the molecular structure of the impregnation solution that makes the modified activated carbon have a high methanol removal capacity according to the corresponding relationship.

[0046] The 31 functional groups, their types, and their corresponding physicochemical properties such as melting and boiling points and flash points, as well as their property contribution values, were listed in an Excel spreadsheet (as shown in Table 1-2) as input information for the mathematical model of the molecular structure. The data in the spreadsheet was read using GAMS software in conjunction with Excel software as parameter input.

[0047] In GAMS 24.7.1, a decomposition-based strategy is used to solve the model. During the calculation, the constraint equations (Equations 1-15) are first used as constraints on the mathematical model. The CPLEX solver is used to generate a library of candidate impregnating solvent molecules that satisfy all constraint equations. Then, based on Equations 16-17, the Newton-Raphson iteration method is used to solve the phase equilibrium model to predict the solvent loading on the activated carbon. The molecular performance is evaluated according to the objective function. Finally, the solvent molecule with the best formaldehyde removal performance after modification with the impregnating solvent molecule can be selected from the solvent molecule library. The specific steps in the calculation process are as follows: In GAMS 24.7.1, set K is defined, containing the 31 groups from the group library; set U is defined, containing the contributions of each group to different molecular properties, such as element U1 = T. m，k and element U2=T b，k The k groups that make up the molecule represent the molecular melting point T. m and boiling point T b The contribution value of different groups to different properties is fixed, and the specific value is obtained from experiments or can be found in the literature; define a set P, in which the elements are the types of different groups; In GAMS 24.7.1, parameters are defined as the contribution of functional groups to various molecular properties and the upper and lower limits of various molecular properties. In GAMS 24.7.1, define variables, namely the types of various groups that make up the molecule and the number of each group; In GAMS 24.7.1, equations are defined, including molecular structural constraints, molecular property constraints, phase equilibrium equations for predicting molecular adsorption amounts, and objective functions. f ; In the mathematical model, the mass of activated carbon is set to 5g, the average pore size of the activated carbon is less than 5nm, and the average specific surface area is greater than 800m². 2 / g.

[0048] In this embodiment, the relevant parameter values ​​are shown in Table 2 below.

[0049] Table 2 (5) Through the above calculation process, it can be determined that multiple molecular structures satisfy the design constraints of the above impregnation liquid molecules. One of them, triethylenetetramine molecule, actually exists and satisfies all the above impregnation liquid molecule design constraints. Furthermore, the activated carbon modified with it has a theoretically high formaldehyde removal performance. The calculation results are shown in Table 3.

[0050] Table 3 (6) Verify the triethylenetetramine modified activated carbon and test its formaldehyde removal ability.

[0051] Preparation of supported activated carbon by impregnation solution modification: 3 parts (5g each) of activated carbon with an average pore size less than 5nm and an average specific surface area greater than 800m² were used. 2 / g of coconut shell activated carbon AC was labeled as Sample 1, Sample 2, and Sample 3, respectively. After drying in a vacuum drying oven at 80℃ for 24 hours, 37.5g of a 65g / L triethylenetetramine impregnation solution (a mixture of triethylenetetramine and water, with water as the carrier solvent for triethylenetetramine) was measured and mixed with the activated carbon AC in glass reagent bottles. The reagent bottles were placed in a constant temperature water bath shaker and impregnated at 120r / min for 48 hours in a 318K water bath. The impregnation solution and activated carbon were separated by filtration. After drying, three samples of supported activated carbon ACM were prepared. Performance test: The three samples of activated carbon AC and supported ACM were tested according to the national standard GB / T 18801-2015 "Air Purifiers" for formaldehyde clean air delivery rate. The test results are as follows: Figure 1 As shown.

[0052] according to Figure 1 The test results show that the formaldehyde removal performance of the prepared triethylenetetramine-modified activated carbon is significantly improved compared with that of the unmodified activated carbon, verifying the reliability of the design method of the environmentally friendly activated carbon high-efficiency formaldehyde removal modified amine impregnation solution in this invention. The modified activated carbon prepared by the impregnation solution designed by the method of this invention has strong formaldehyde purification capacity and environmentally friendly properties, reducing the workload of experimental screening.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for designing impregnation liquid molecules, characterized in that, Includes the following steps: S1. Constructing a group library for the molecular structure of the impregnation solution; S2. Molecular structure and property constraints for constructing the molecular structure model of the impregnation solution; S3. Construct the relationship between the equilibrium adsorption amount of impregnation liquid molecules on activated carbon and the relationship between the theoretical formaldehyde removal capacity of the modified activated carbon obtained after the impregnation liquid molecules are modified. S4. Use GAMS software for simulation calculation and determine the molecules of the impregnation liquid; the calculation process specifically includes the following steps: construct a molecular library of molecular structure models of the impregnation liquid based on the molecular structure and property constraints described in step S2; then determine the molecular structure of the impregnation liquid from the molecular library based on the relationship of equilibrium adsorption amount described in step S3 and the relationship of the theoretical formaldehyde removal capacity of modified activated carbon.

2. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S1, the group library of the impregnation liquid molecular structure includes amine groups.

3. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S1, the group library of the impregnation liquid molecular structure is constructed by the group contribution method.

4. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S1, the group library of the impregnation liquid molecular structure includes a main chain group set, a functional group set, a chain-terminal group set, a non-chain-terminal group set, an aromatic group set, and a group set containing carbon-carbon double bonds.

5. The method for designing impregnation liquid molecules as described in claim 4, characterized in that, In step S2, the molecular structure and property constraints include at least one of the following terms: (a) The constraint equation for the molecular structure being limited to one of the following: acyclic, monocyclic, or bicyclic molecules is: （1）， Among them, the binary variable y a y m 、 and y b These indicate whether the three structures of acyclic, monocyclic, or bicyclic molecules exist in the designed molecule, respectively. (b) The constraint equations for molecules with a valence of 0 and where no more than one bond can be connected between any two adjacent groups are as follows: （2）， （3）； Equation 2 is the molecular structure constraint equation, and Equation 3 is the molecular connection mode constraint equation, N k and ν k These are the number of groups k in the molecule and their valence, respectively. (c) The constraint equations imposed on the number of aromatic and non-aromatic groups and the manner in which they are connected include: （4）， （5）； Equation 4 is the number constraint equation for aromatic and non-aromatic groups, and Equation 5 is the connection mode constraint equation for aromatic and non-aromatic groups. Ar N represents a collection of aromatic groups. ac It is the number of aromatic rings in the molecule; This represents the set of non-aromatic groups with a valence greater than or equal to 3. This represents the set of aromatic groups with a valence greater than or equal to 3, where AR and NAR represent aromatic and non-aromatic groups, respectively. The valence of group k is m = y. a -y b y a and y b It is a binary variable. When the value of m is -1, 0 or 1, it represents that the molecular structure is a bicyclic molecule, a monocyclic molecule or an acyclic molecule, respectively. (d) The constraint equation for the number of double bond groups in the molecule is shown in Equation 6: （6）； Among them, G D This represents a set of groups containing carbon-carbon double bonds; (e) The quantity restriction equations for various types of functional groups include: （7）， （8）； Equation 7 is the constraint equation for the number of main chain groups in the molecule, and Equation 8 is the constraint equation for the number of functional groups in the molecule. M G represents the set of main chain groups. F Represented as a set of functional groups, N max This indicates the maximum number of functional groups in a molecule; (f) The melting and boiling points of the impregnation solution molecules must ensure that the impregnation solution is liquid at room temperature and pressure to meet the impregnation requirements. The constraint equation for this property is: （9）, （10）； Equation 9 is the molecular melting point constraint equation, and Equation 10 is the molecular boiling point constraint equation. m,k and T b,k These are the contributions of group k to the melting and boiling points of the molecule in the group contribution method; T m,0 and T b,0 These are constants in the model for estimating the melting and boiling points of the impregnating solution molecules; T m,max and T b,min These represent the maximum value of the melting point of the impregnating liquid molecules and the minimum value of the boiling point of the molecules, respectively; (g) The constraint equation for the flash point of the molecule is as follows: Equation 11: （11）， Among them, F p,k F is the contribution of group k to the molecular flash point in the group contribution method. p,min It is the minimum flash point of the impregnating liquid molecules required by the design; (h) The constraint equations for the aquatic biotoxicity of molecules, soil enrichment coefficients, and environmental properties of bioconcentration factors include: （12）， （13）， （14）； Wherein, Equation 12 is the constraint equation for molecular aquatic biotoxicity, Equation 13 is the constraint equation for molecular soil enrichment coefficient, and Equation 14 is the constraint equation for molecular bioconcentration factor. LC k K ow and BCF k These are the contributions of group k to the aquatic biotoxicity of the impregnating solution molecules, the soil enrichment coefficient, and the bioconcentration factor, respectively; LC max K oc,max and BCF max These are the maximum values ​​of the molecular aquatic organism toxicity concentration, soil enrichment coefficient, and bioconcentration factor of the designed impregnation solution; (e) The constraint equation for the number of amine groups in the molecule is as follows: Equation 15: （15）； Where, N 25 N 27 N 28 and N 29 These represent the number of amino groups 25, 27, 28, and 29, respectively. 25, 27, 28, and 29 are the numbers of ACNH2 group, CH2NH2 group, CH3NH group, and CH2NH group, respectively.

6. The method for designing impregnation liquid molecules as described in claim 5, characterized in that, Includes at least one of the following: The T m,max 250-313K; The T b,min 353K-393K; The F p,min 290-330K; The LC max It is 1-10 mol / L; The K oc,max It is 10-30; The BCF max The range is 1-8.

7. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S3, the relationship of the equilibrium adsorption amount includes the following formula 16: （16）； in, and The components are respectively i Mole fraction in bulk phase and adsorbed solid solution; and The components are respectively i Activity coefficient in bulk phase and adsorbed solid solution; It is the difference in chemical potential between the wetted adsorbent before adsorption and after adsorption of component i. T , R and These are adsorption temperature, ideal gas constant, and composition. i Surface phase capacity.

8. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S3, the theoretical formaldehyde removal capacity of the modified activated carbon is expressed as shown in Equation 17: （17）； in, It is the saturation adsorption capacity of activated carbon for adsorbing molecules. It refers to the quality of activated carbon; N 25 N 27 N 28 and N 29 These represent the number of amino groups 25, 27, 28, and 29, respectively. 25, 27, 28, and 29 are the numbers of ACNH2 group, CH2NH2 group, CH3NH group, and CH2NH group, respectively.

9. The method for designing impregnation liquid molecules as described in claim 1, characterized in that, In step S4, the calculation process further includes the following steps: defining sets, parameters, variables, and equations in the software.

10. The method for designing impregnation liquid molecules as described in claim 9, characterized in that, Includes at least one of the following: The set includes set K, set U and set P. The elements in set K are the groups in the group library, the elements in set U are the contribution values ​​of each group to different properties of the molecule, and the elements in set P are the types of different groups. The variables include the types of various functional groups that make up the impregnation liquid molecules and the number of each functional group; The equations include the constraint equations among the molecular structure and property constraints, the relationship of the equilibrium adsorption amount, and the relationship of the theoretical formaldehyde removal capacity of the modified activated carbon.

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