Highland barley straw adsorbent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of adsorbents, and particularly relates to a highland barley straw adsorbent and a preparation method and application thereof. The preparation method of the highland barley straw adsorbent comprises the following steps: placing highland barley straws in an ester compound aqueous solution for esterification treatment to remove protein and grease components in the highland barley straws so as to obtain esterified highland barley straws; the esterified highland barley straw is placed in a cellulase solution for enzymolysis treatment, and enzymolysis highland barley straw is obtained; and carrying out enzyme deactivation treatment on the enzymolysis highland barley straws, cleaning to be neutral, drying, and crushing to obtain the highland barley straw adsorbent. According to the highland barley straw adsorbent prepared by the method, the adsorption capacity of PM2.5 in air can be remarkably improved, the defect of the existing adsorbent in the aspect of adsorption capacity is effectively improved, the resource utilization of the agricultural waste highland barley straw is also realized, and the resource waste and the environmental pollution are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorbents, and particularly relates to a highland barley straw adsorbent and a preparation method and application thereof. Background Art

[0002] Highland barley is an annual herb with the characteristics of short growth cycle, cold resistance and strong tolerance. It is mainly planted in the plateau area of ​​my country and is one of the characteristic crops in the Qinghai-Tibet region of my country. In Tibetan areas, highland barley straw is widely used for burning for heating and feeding livestock, so it is not used efficiently. If highland barley waste is not properly processed and treated, it is not only a waste of resources, but also a large amount of stacking will easily lead to rot, aggravating air pollution.

[0003] In response to the air pollution caused by modern urban and industrial development, especially PM2.5 (fine particulate matter) pollution, the adsorbents currently prepared by existing technical methods, such as diatomaceous earth and activated carbon, have good adsorption performance, but the diatomaceous earth resources are limited and the mining cost is high, which limits its large-scale application; and activated carbon is obtained by calcining biomass in an oxygen-free environment at the cost of cutting down trees and destroying forest resources. Its adsorption capacity is relatively small and it is easy to reach saturation in a short time and lose the adsorption effect. As an agricultural waste unique to the Qinghai-Tibet region, highland barley straw is regarded as a raw material with great potential for the development of new adsorbents due to its high fiber content and unique chemical structure. However, the highland barley straw adsorbent directly used as an adsorbent, that is, the highland barley straw adsorbent obtained by washing the highland barley straw, drying it, and crushing it, has the problems of low efficiency and limited adsorption capacity. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a highland barley straw adsorbent and a preparation method and application thereof. The highland barley straw adsorbent is prepared by esterification and enzymolysis treatment with highland barley straw as raw material. The highland barley straw adsorbent obtained by the method of the present invention can not only significantly improve the adsorption capacity for PM2.5 in the air, effectively improve the deficiency of the existing adsorbent in adsorption capacity, but also realize the resource utilization of highland barley straw, an agricultural waste, and reduce resource waste and environmental pollution.

[0005] In order to achieve the above purpose, the technical solution adopted in this application is:

[0006] The first object of the present invention is to provide a method for preparing a highland barley straw adsorbent, comprising the following steps:

[0007] S1. Cleaning samples: Take highland barley straw and rinse it under running water to remove dust and impurities on the surface of the highland barley straw.

[0008] S2. High temperature cooking: The cleaned highland barley straw is placed in boiling water for cooking to remove soluble substances in the highland barley straw.

[0009] S3, esterification treatment: preparing an ester compound aqueous solution, soaking the cooked highland barley straw in the ester compound aqueous solution and then performing an esterification treatment to remove protein and oil components in the highland barley straw to obtain esterified highland barley straw.

[0010] S4. Cellulase heat treatment: prepare a cellulase solution, place the esterified highland barley straw in the cellulase solution for enzymolysis treatment to extract water-insoluble cellulose in the highland barley straw, and obtain degraded highland barley straw.

[0011] S5. Enzyme inactivation treatment: placing the degraded highland barley straw in a water bath for enzyme inactivation treatment to terminate the activity of cellulase, ensure the stability and safety of the adsorbent, and obtain highland barley straw adsorbent.

[0012] S6. Adjusting pH: Rinse the highland barley straw adsorbent with deionized water for multiple times until it is neutral, so as to remove residual cellulase and ester compounds.

[0013] S7. Drying and crushing samples: The washed highland barley straw adsorbent is placed in a blast drying oven to dry and then crushed.

[0014] Preferably, in the aqueous solution of the ester compound, the ester compound is selected from one of ethyl acetate, butyl acetate, amyl acetate, hexyl acetate, heptyl acetate, octyl acetate, isoamyl acetate or isooctyl acetate, and the concentration of the aqueous solution of the ester compound is 0.07 mol / L to 0.23 mol / L.

[0015] Preferably, the ester compound is selected from ethyl acetate. The reaction conditions of ethyl acetate are mild and it is not easy to destroy the basic structure of highland barley straw. Its good volatility facilitates subsequent removal and reduces the pollution of highland barley straw adsorbent. In addition, its toxicity is low and the impact on the environment and human health is small.

[0016] Preferably, the method for esterification treatment in step S4 is: soaking the highland barley straw in an ethyl acetate solution for 17.3 h to 30.7 h.

[0017] Preferably, the mass concentration of the cellulase solution in the enzymatic hydrolysis treatment in step S4 is 0.1 mg / mL to 0.5 mg / mL.

[0018] Preferably, the enzymatic treatment time in step S4 is 10 minutes; if the enzymatic treatment time exceeds 10 minutes, the cellulose will be over-hydrolyzed, its structure will be destroyed, and the adsorption capacity of the adsorbent will be reduced; if the enzymatic treatment time is less than 10 minutes, the cellulase will not be able to fully act on the cellulose in the highland barley straw, resulting in incomplete extraction of water-insoluble cellulose, affecting the final effect of the adsorbent.

[0019] Preferably, the temperature of the enzyme inactivation treatment in step S5 is 75°C and the time is 10 minutes; wherein, if the enzyme inactivation treatment time exceeds 10 minutes, although it can ensure that the cellulase is completely inactivated, excessive treatment time will cause changes in the properties of the highland barley straw adsorbent, such as structural damage or reduced function; if the enzyme inactivation time is less than 10 minutes, the cellulase cannot be completely inactivated, and the residual enzyme activity causes the cellulose to continue to degrade during post-processing or use, affecting the stability and effect of the adsorbent.

[0020] Preferably, in step S7, the highland barley straw adsorbent is rinsed to neutrality and then dried at 80°C.

[0021] The second object of the present invention is to provide a highland barley straw adsorbent prepared by the above preparation method.

[0022] Preferably, the particle size of the highland barley straw adsorbent is 18 mesh to 100 mesh.

[0023] The third object of the present invention is to provide the use of the above-mentioned highland barley straw adsorbent in the preparation of PM2.5 adsorbent.

[0024] Preferably, the highland barley straw adsorbent is placed in a closed air atmosphere containing PM2.5 for adsorption treatment.

[0025] Preferably, the ratio of the mass of the highland barley straw adsorbent to the amount of PM2.5 is 1g to 5g: 300μg / m 3 ~700 μg / m 3 .

[0026] Preferably, the ratio of the mass of the highland barley straw adsorbent to the amount of PM2.5 is 4g:300μg / m 3 .

[0027] Preferably, the adsorption temperature of the highland barley straw adsorbent is room temperature, and the adsorption time is 20 min to 60 min.

[0028] Preferably, the adsorption temperature of the highland barley straw adsorbent is 14°C to 30°C.

[0029] Preferably, the particle size of the highland barley straw adsorbent is 60 mesh, the adsorption temperature is 22° C., and the adsorption time is 50 min.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention provides a method for preparing a highland barley straw adsorbent, wherein highland barley straw is first subjected to an ester compound aqueous solution for esterification treatment, and then enzymolyzed in a cellulase solution, and then the enzymolyzed is subjected to an enzyme inactivation treatment, and then dried and crushed to obtain a highland barley straw adsorbent. The highland barley straw adsorbent prepared by the method can not only significantly improve the adsorption capacity of PM2.5 in the air, effectively improve the deficiency of existing adsorbents in adsorption capacity, but also realize the resource utilization of highland barley straw, an agricultural waste, and reduce resource waste and environmental pollution.

[0032] Among them, during the esterification process, ethyl acetate was used as a solvent and reactant to effectively remove the non-cellulose components of protein and oil in highland barley straw; then, under the action of cellulase, enzymatic hydrolysis targetedly degraded part of the non-crystalline cellulose in highland barley straw, exposing more fine fibers and pore structures without destroying the overall skeleton, thereby increasing the specific surface area of ​​the highland barley straw adsorbent. This porous structure provides abundant adsorption sites for PM2.5, enabling the highland barley straw adsorbent to efficiently capture and fix PM2.5 in the air. In addition, enzymatic hydrolysis also improves the surface chemical properties of highland barley straw, enhances its surface hydrophilicity and adsorption capacity, and is conducive to PM2.5 being firmly adsorbed on the surface of highland barley straw adsorbent through electrostatic attraction, surface adsorption or chemical bonding. The enzyme inactivation treatment ensures that the cellulase is completely inactivated, avoids the influence of the continuous action of the enzyme on the structure of the highland barley straw adsorbent in subsequent use, and ensures the stability and reusability of the highland barley straw adsorbent.

[0033] Through the synergistic effect of esterification and enzymatic hydrolysis, the highland barley straw adsorbent of the present invention not only removes impurities and retains the advantageous properties of cellulose in highland barley straw, but also significantly improves the adsorption efficiency and capacity of the highland barley straw adsorbent for PM2.5 by constructing a rich pore structure and improving surface properties.

[0034] 2. The highland barley straw adsorbent obtained by the present invention has better adsorption performance and good environmental protection characteristics than the existing technologies such as diatomaceous earth, activated carbon and macroporous adsorption resin AB-8. It can not only solve the problems of resource waste and environmental pollution caused by insufficient utilization of highland barley straw, but also significantly enhance its adsorption capacity for PM2.5 in the air, thereby achieving the dual goals of resource utilization and environmental protection.

[0035] Among them, before and after the highland barley straw adsorbent adsorbs PM2.5, the stretching vibration of the -OH group undergoes displacement and intensity changes, indicating that the -OH group plays an important role in the adsorption process; further studies have shown that the adsorption law of highland barley straw adsorbents on PM2.5 is more in line with the quasi-secondary kinetic model, which is usually related to chemical adsorption; at the same time, adsorption isotherm studies have shown that the adsorption process is mainly based on multilayer adsorption of multiple active sites, indicating that in addition to chemical adsorption, physical adsorption also plays an important role. Therefore, a variety of intermolecular interactions occur between the highland barley straw adsorbent of the present invention and PM2.5, including physical interactions, such as electrostatic attraction, van der Waals forces and chemical interactions, such as chemical bonding between -OH groups and PM2.5. The combined effect of these effects makes the highland barley straw adsorbent produce a significant adsorption effect on PM2.5.

[0036] 3. The present invention also uses highland barley straw adsorbent to remove PM2.5 in the air. When the particle size of highland barley straw adsorbent is 60 mesh, the addition amount is 4g, the adsorption temperature is 22℃, the adsorption time is 50min, and the initial PM2.5 content is 300μg / m 3 The removal rate can reach up to 21.32%, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a single factor effect analysis diagram of highland barley straw adsorbent in Examples 1 to 19.

[0038] Figure 2 These are the PM2.5 removal effect diagrams of highland barley straw adsorbents of Examples 1 to 19, wherein (a) is the PM2.5 removal effect diagram of cellulase mass concentration (X1) and ethyl acetate concentration (X2), and (b) is the PM2.5 removal effect diagram of cellulase mass concentration (X1) and soaking time (X3).

[0039] Figure 3 5. The figures are as follows: (a) is the effect of the particle size of the highland barley straw adsorbent on the adsorption effect of PM2.5 in Example 1, (b) is the effect of the amount of highland barley straw adsorbent added in Example 1 on the adsorption effect of PM2.5, (c) is the effect of the adsorption temperature of the highland barley straw adsorbent on the adsorption effect of PM2.5, (d) is the effect of the adsorption time of the highland barley straw adsorbent in Example 1 on the adsorption effect of PM2.5, and (e) is the adsorption effect of the highland barley straw adsorbent in Example 1 on PM2.5 at different initial PM2.5 contents.

[0040] Figure 4The figures are scanning electron microscope images of original highland barley straw and the highland barley straw adsorbent of Example 1 before and after adsorption, wherein (a) is a scanning electron microscope image of original highland barley straw, (b) is a scanning electron microscope image of the highland barley straw adsorbent of Example 1 before adsorption, and (c) is a scanning electron microscope image of the highland barley straw adsorbent of Example 1 after adsorption.

[0041] Figure 5 The infrared curves of the original highland barley straw and the highland barley straw adsorbent of Example 1 before and after adsorption, (a) is the infrared curve of the original highland barley straw, (b) is the infrared curve of the highland barley straw adsorbent of Example 1 before adsorption, and (c) is the infrared curve of the highland barley straw adsorbent of Example 1 after adsorption.

[0042] Figure 6 This is a diagram showing the adsorption effect of highland barley straw adsorbent on PM2.5 at different initial PM2.5 contents in Example 1.

[0043] Figure 7 These are isotherms of PM2.5 adsorption by highland barley straw adsorbent in Example 1, wherein (a) Example 1 is a Langmuir isotherm of PM2.5 adsorption by highland barley straw adsorbent, and (b) Example 1 is a Freundlich isotherm of PM2.5 adsorption by highland barley straw adsorbent.

[0044] Figure 8 This is a diagram showing the adsorption effect of highland barley straw adsorbent on PM2.5 at different adsorption times in Example 1.

[0045] Fig. 9 The graphs are the adsorption rate equations of PM2.5 by highland barley straw adsorbent in Example 1, wherein (a) is a pseudo-first-order rate equation graph, and (b) is a pseudo-second-order rate equation graph.

[0046] Fig.10 This is a diagram showing the adsorption effect of highland barley straw adsorbent on PM2.5 at different adsorption temperatures in Example 1.

[0047] Fig.11 This is a fitting diagram of the thermodynamic equation for PM2.5 adsorption by highland barley straw adsorbent in Example 1.

[0048] Fig.12 This is a diagram showing the adsorption effect of different adsorption materials on PM2.5.

[0049] Fig.13 This is the desorption and regeneration diagram of the highland barley straw adsorbent in Example 1.

[0050] Fig.14 This is a diagram showing the adsorption effect of the highland barley straw adsorbent on PM2.5 prepared in Examples 16 to 19 and Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be clearly and completely described below in combination with the data in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0053] In the existing technology, traditional adsorbents do show effectiveness in removing air pollutants, such as diatomaceous earth and activated carbon, but they are scarce, costly, and have limited regeneration capacity. In contrast, highland barley straw, as an agricultural waste unique to the Qinghai-Tibet region, is considered a highly potential raw material for developing new adsorbents due to its high fiber content and unique chemical structure. However, the direct use of highland barley straw as an adsorbent has the problems of low efficiency and limited adsorption capacity.

[0054] In view of the problems existing in the prior art, the present invention provides a method for preparing a highland barley straw adsorbent, comprising the following steps: placing highland barley straw in an ester compound aqueous solution for esterification treatment to remove protein and oil components in the highland barley straw to obtain esterified highland barley straw; placing the esterified highland barley straw in a cellulase solution for enzymolysis treatment to obtain enzymolyzed highland barley straw; performing enzyme inactivation treatment on the enzymolyzed highland barley straw, then washing it to neutrality, drying it, and crushing it to obtain a highland barley straw adsorbent.

[0055] The present invention utilizes ester compounds to assist cellulase in preparing highland barley straw adsorbents. Through the synergistic effect of esterification and enzymatic hydrolysis, not only impurities are removed, the advantageous characteristics of cellulose are retained, but also the adsorption efficiency and capacity of PM2.5 particles are significantly improved by constructing a rich pore structure and improving surface properties. In addition, the highland barley straw adsorbent treated with esterification and enzymatic hydrolysis has a large specific surface area and a rich pore structure, and can effectively adsorb PM2.5 particles in the air. At the same time, the resource utilization of highland barley straw, an agricultural waste, is realized, and resource waste and environmental pollution are reduced.

[0056] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0057] Example 1

[0058] A method for preparing a highland barley straw adsorbent comprises the following steps:

[0059] S1. Cleaning samples: Weigh highland barley straw and rinse it under running water to remove dust and impurities on the surface of the highland barley straw.

[0060] S2. High temperature cooking: Cook the washed highland barley straw in boiling water for 0.5 h.

[0061] S3. Esterification treatment: The cooked highland barley straw is immersed in a 0.2 mol / L ethyl acetate solution for 28 hours for esterification treatment.

[0062] S4. Cellulase heat treatment: The esterified highland barley straw was placed in 500 mL of a cellulase solution with a mass concentration of 0.45 mg / mL, and subjected to enzymatic hydrolysis in a water bath at 50° C. for 1 h.

[0063] S5. Enzyme inactivation treatment: Place the enzymatically hydrolyzed highland barley straw in a 75°C water bath for 10 minutes to inactivate the enzyme.

[0064] S6. Adjusting pH: Rinse the highland barley straw after enzyme inactivation treatment with deionized water for multiple times until it becomes neutral.

[0065] S7. Drying and crushing samples: Place the washed highland barley straw in a blast drying oven and dry at 80° C., then crush the sample and pass it through a 60-mesh sieve to obtain a highland barley straw adsorbent.

[0066] Example 2

[0067] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 1, except that the soaking time is replaced from 28 h to 20 h.

[0068] Example 3

[0069] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 1, except that the concentration of the ethyl acetate solution is replaced from 0.2 mol / L to 0.1 mol / L.

[0070] Example 4

[0071] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 3, except that the soaking time is replaced from 28 h to 20 h.

[0072] Example 5

[0073] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 1, except that the mass concentration of the cellulase solution is replaced from 0.45 mg / mL to 0.3 mg / mL.

[0074] Example 6

[0075] A method for preparing a highland barley straw adsorbent has the same preparation steps as those in Example 5, except that the soaking time is replaced from 28 h to 20 h, and the 60-mesh sieve in step S7 is replaced by an 18-mesh sieve.

[0076] Example 7

[0077] A method for preparing a highland barley straw adsorbent has the same preparation steps as those in Example 3, except that the mass concentration of the cellulase solution is replaced from 0.45 mg / mL to 0.35 mg / mL, and the 60-mesh sieve in step S7 is replaced by a 100-mesh sieve.

[0078] Example 8

[0079] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 7, except that the soaking time is replaced from 28 h to 20 h.

[0080] Example 9

[0081] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 1, except that the concentration of the ethyl acetate solution is replaced from 0.2 mol / L to 0.15 mol / L, the mass concentration of the cellulase solution is replaced from 0.45 mg / mL to 0.32 mg / mL, and the soaking time is replaced from 28 h to 24 h.

[0082] Example 10

[0083] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 9, except that the mass concentration of the cellulase solution is replaced from 0.32 mg / mL to 0.48 mg / mL.

[0084] Embodiment 11

[0085] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 9, except that the concentration of the ethyl acetate solution is replaced from 0.15 mol / L to 0.07 mol / L, and the mass concentration of the cellulase solution is replaced from 0.32 mg / mL to 0.4 mg / mL.

[0086] Example 12

[0087] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 11, except that the concentration of the ethyl acetate solution is replaced from 0.07 mol / L to 0.23 mol / L.

[0088] Embodiment 13

[0089] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 12, except that the concentration of the ethyl acetate solution is replaced from 0.23 mol / L to 0.15 mol / L, and the soaking time is replaced from 24 h to 17.3 h.

[0090] Embodiment 14

[0091] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 13, except that the soaking time is replaced from 17.3 h to 30.7 h, and the 60-mesh sieve in step S7 is replaced by an 18-mesh sieve.

[0092] Embodiment 15

[0093] A method for preparing a highland barley straw adsorbent has the same preparation steps as those of Example 13, except that the soaking time is replaced from 17.3 h to 24 h, and the 18-mesh sieve in step S7 is replaced by a 60-mesh sieve.

[0094] Based on Example 15, 9 groups of parallel tests were conducted, and the average removal rate was 7.9%.

[0095] Example 16

[0096] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 15, except that the mass concentration of the cellulase solution is replaced from 0.4 mg / mL to 0.1 mg / mL.

[0097] Embodiment 17

[0098] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 15, except that the mass concentration of the cellulase solution is replaced from 0.4 mg / mL to 0.2 mg / mL.

[0099] Embodiment 18

[0100] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 15, except that the mass concentration of the cellulase solution is replaced from 0.4 mg / mL to 0.3 mg / mL.

[0101] Embodiment 19

[0102] A method for preparing a highland barley straw adsorbent is the same as the preparation steps of Example 15, except that the mass concentration of the cellulase solution is replaced from 0.4 mg / mL to 0.5 mg / mL.

[0103] On the basis of the single factor experiment, the mass concentration of cellulase solution (X1), ethyl acetate solution concentration (X2) and soaking time (X3) were selected as optimization factors. The three-factor quadratic regression orthogonal rotation combination design was obtained using DPS software. Twenty-three different secondary highland barley straw adsorbents were prepared, and 23 groups of experiments were designed to evaluate the removal rate of highland barley straw adsorbents, as shown in Tables 1 and 2.

[0104] Table 1 Three-factor quadratic regression orthogonal rotation combination test design and result test table

[0105]

[0106]

[0107] Table 2 ANOVA table

[0108]

[0109]

[0110] In order to optimize the best process conditions for extracting highland barley straw biomass adsorbent, a quadratic regression orthogonal rotation analysis experiment was carried out with cellulase mass concentration (X1), ethyl acetate concentration (X2), and soaking time (X3) as independent variables and adsorption rate (Y) as response value. The experimental results were analyzed using the DPS system, and the mathematical model regression equation of cellulase mass concentration (X1), ethyl acetate concentration (X2), soaking time (X3), and removal rate (Y) was obtained as follows:

[0111] Y=7.91500+0.80978X1-0.02563X2-0.26590X3+0.69817X1 2 +0.69817X2 2 +0.3569

[0112] 9X3 2 +0.71000X1X2+0.64250X1X3+0.16750X2X3

[0113] Where: Lack of Fit F1 = 3.484 <F 0.01(5,8) =6.63, which did not reach the significant level, that is, the unknown factors had little effect on the experiment and the experimental error was small; regression F2 = 11.553 > F 0.01(9,13) =4.19, reaching the 1% extremely significant level, and the regression equation predicts accurately.

[0114] The significance test of the regression coefficient was carried out, and the insignificant items at the α=0.10 level were eliminated. The variance analysis was carried out again on the remaining items to form a simplified regression equation (α=0.10):

[0115] Y=7.91500+0.80978X1+0.69817X1 2 +0.69817X2 2 +0.35699X3 2 +0.71000X1X2+0.

[0116] 64250X1X3

[0117] Table 3 Single factor effect analysis (other factors are zero level)

[0118] level <![CDATA[X1]]> <![CDATA[X2]]> <![CDATA[X3]]> -1.682 8.528 9.890 8.925 -1.341 8.084 9.170 8.557 -1 7.803 8.613 8.272 -0.5 7.685 8.090 8.004 0 7.915 7.915 7.915 0.5 8.494 8.090 8.004 1 9.423 8.613 8.272 1.341 10.256 9.170 8.557 1.682 11.252 9.890 8.925

[0119] In order to further evaluate the influence of the interaction among X1, X2 and X3 on the comprehensive score of removal efficiency Y and determine the optimal level range of each factor, the corresponding response surface diagram was drawn according to the analysis results.

[0120] Figure 1 This is a single factor effect analysis diagram of highland barley straw adsorbent in Examples 1 to 19, Figure 1 The cellulase mass concentration curve shows that with the increase of mass concentration, the PM2.5 removal rate of highland barley straw adsorbent turns from -0.5 level and begins to turn from a downward trend to an upward trend. When the cellulase mass concentration is 0.48 mg / mL, the PM2.5 removal rate is 11.252%.

[0121] According to the ethyl acetate concentration curve, the PM2.5 removal rate of highland barley straw adsorbent is based on the 0 level. When the level is less than 0, the trend is gradually decreasing, and when the level is greater than 0, the trend is gradually increasing. When the concentration is 0.07mol / L and 0.23mol / L, the PM2.5 removal rate can reach 9.89%.

[0122] The ethyl acetate soaking time curve shows that the PM2.5 removal rate of highland barley straw adsorbent is based on the 0 level. When the level is less than 0, the trend is gradually decreasing, and when the level is greater than 0, the trend is gradually increasing. When the soaking time is 17.3h and 30.7h, the PM2.5 removal rate can reach 8.925%.

[0123] Figure 2 The following are the PM2.5 removal effects of highland barley straw adsorbents in Examples 1 to 19. Figure 2 (a) is the removal effect of cellulase mass concentration (X1) and ethyl acetate concentration (X2), (b) is the removal effect of cellulase mass concentration (X1) and soaking time (X3). Figure 2 (a), (b), combined with the data in Table 4 and Table 5, it can be concluded that in the three groups of two-factor interactions X1X2, X1X3, and X2X3, the influence of X1X2 and X1X3 is more significant.

[0124] Table 4 Effect of cellulase mass concentration (X1) and ethyl acetate concentration (X2) on removal rate

[0125]

[0126] Table 5 Effect of cellulase mass concentration (X1) and soaking time (X3) on removal rate

[0127]

[0128]

[0129] The experimental data were analyzed by DPS software, and the levels of the three factors when the Y value was the largest were found at (1.682, 1.682, 1.682), that is, the cellulase concentration was 0.48 mg / ml, the ethyl acetate concentration was 0.23 mol / L, and the soaking time was 30.7 h. At this time, the predicted removal rate Y max Under this adsorption condition, the removal rate was 17.92% and the actual value / model optimal value was 0.992, which was close to 1, indicating that the model prediction was accurate.

[0130] Comparative Example 1

[0131] A method for preparing a highland barley straw adsorbent, which adopts an alkali-heat method to prepare the highland barley straw adsorbent, comprises the following steps:

[0132] S1. Cleaning samples: Weigh highland barley straw and rinse it under running water to remove dust and impurities on the surface of the highland barley straw.

[0133] S2. High temperature cooking: Cook the washed highland barley straw in boiling water for 0.5 h.

[0134] S3. Alkali heat treatment: the cooked highland barley straw is placed in a 0.1 mol / L caustic soda solution and soaked at 60° C. for 1 hour for alkaline heat treatment.

[0135] S4. Adjusting pH: Rinse the highland barley straw after alkali heat treatment with deionized water several times until it becomes neutral.

[0136] S6. Drying and crushing samples: Place the washed highland barley straw in a blast drying oven to dry at 80° C., crush it, and pass it through a 40-mesh sieve to obtain a highland barley straw adsorbent.

[0137] On the basis of comparative example 1, the concentration of caustic soda solution was screened, and the concentrations were 0.2 mol / L, 0.3 mol / L, 0.4 mol / L and 0.5 mol / L respectively.

[0138] Comparative Example 2

[0139] A method for preparing a highland barley straw adsorbent, which adopts an acid coenzyme method to prepare the highland barley straw adsorbent, comprises the following steps:

[0140] S1. Cleaning samples: Weigh highland barley straw and rinse it under running water to remove dust and impurities on the surface of the highland barley straw.

[0141] S2. High temperature cooking: Cook the washed highland barley straw in boiling water for 0.5 h.

[0142] S3. Acidification treatment: The cooked highland barley straw is placed in a 0.1 mol / L citric acid solution and soaked for 0.5 h for acidification treatment.

[0143] S4. Hemicellulase heat treatment: The acidified highland barley straw was placed in 500 mL of a hemicellulase solution with a mass concentration of 0.1 mg / mL, and subjected to enzymatic hydrolysis in a water bath at 50° C. for 0.5 h.

[0144] S5. Enzyme inactivation treatment: Place the enzymatically hydrolyzed highland barley straw in a 70°C water bath for 20 minutes to inactivate the enzyme.

[0145] S6. Adjusting pH: Rinse the highland barley straw after enzyme inactivation treatment with deionized water several times until it becomes neutral.

[0146] S7. Drying and crushing the sample: Place the washed highland barley straw in a blast drying oven to dry at 80° C., crush it, and pass it through a 40-mesh sieve to obtain a highland barley straw adsorbent.

[0147] On the basis of Comparative Example 2, the mass concentration of hemicellulase was screened, and the mass concentrations of hemicellulase were 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL and 0.5 mg / mL respectively.

[0148] Comparative Example 3

[0149] A method for preparing a highland barley straw adsorbent, which adopts a salting-out coenzyme method to prepare the highland barley straw adsorbent, comprises the following steps:

[0150] S1. Cleaning samples: Weigh highland barley straw and rinse it under running water to remove dust and impurities on the surface of the highland barley straw.

[0151] S2. High temperature cooking: Cook the washed highland barley straw in boiling water for 0.5 h.

[0152] S3. Salting-out treatment: The cooked highland barley straw is placed in a 0.15 mol / L KCl solution and soaked for 0.5 h for salting-out treatment.

[0153] S4. Adjusting pH: Rinse the highland barley straw after salting out with deionized water for several times until it becomes neutral.

[0154] S5. Lignin peroxidase heat treatment: The highland barley straw after salting out was placed in 500 mL of 4 mg / mL cellulase solution and subjected to enzymatic hydrolysis in a water bath at 55° C. for 0.5 h.

[0155] S6. Enzyme inactivation treatment: Place the enzymatically hydrolyzed highland barley straw in a 75°C water bath for 10 minutes to inactivate the enzyme.

[0156] S7. Adjusting pH: Rinse the highland barley straw after enzyme inactivation treatment with deionized water several times until it becomes neutral.

[0157] S8. Drying and crushing samples: Place the washed highland barley straw in a blast drying oven and dry at 80° C., then crush it and pass it through a 40-mesh sieve to obtain a highland barley straw adsorbent.

[0158] On the basis of Comparative Example 3, the mass concentration of lignin peroxidase was screened, and the mass concentrations were 8 mg / mL, 12 mg / mL, 16 mg / mL and 20 mg / mL respectively.

[0159] The specific surface area and pore size (BET) of the highland barley straw adsorbent prepared in Example 1 were analyzed:

[0160] Table 6 Specific surface area and pore size parameter analysis table of highland barley straw adsorbent prepared in Example 1

[0161] Analysis of specific surface area and pore size of highland barley straw adsorbent Measurements <![CDATA[Specific surface area (m 2 / g)]]> 2.9810 <![CDATA[Pore volume (cm 3 / g)]]> 0.0095 Pore ​​size distribution (d) 3.3260

[0162] The highland barley straw adsorbent was further determined by BET analysis, and the specific surface area was found to be 2.9810 m 2 / g, pore volume 0.0095cm 3 / g, and the pore size distribution of 3.3260d further proves that the highland barley straw adsorbent has more adsorption sites and is effective in adsorbing PM2.5.

[0163] Taking the highland barley straw adsorbent prepared in Example 1 of the present invention as an example, it is applied to the removal of PM2.5 in the air atmosphere. The specific application method and results are as follows:

[0164] (1) Single factor test:

[0165] a. Effect of particle size on adsorption of PM2.5

[0166] The crushed highland barley straw adsorbent was passed through 18-mesh, 40-mesh, 60-mesh, 80-mesh and 100-mesh sieves respectively. 2 g of highland barley straw adsorbent with different particle sizes was weighed and placed in a culture dish. Mosquito coils were used to release PM2.5 in a closed box. When the initial PM2.5 content reached 500 μg / m 3 When the highland barley straw adsorbent was placed in a closed box for adsorption for 0.5 h, the removal rate was calculated.

[0167] b. Effect of addition amount on adsorption of PM2.5

[0168] 1.0g, 2.0g, 3.0g, 4.0g, and 5.0g of highland barley straw adsorbent were weighed and placed in culture dishes respectively. Mosquito coils were used to release PM2.5 in a closed box until the mass concentration reached 500μg / m 3 , the highland barley straw adsorbent was placed in a closed box for adsorption for 0.5 h, and the adsorption amount and removal rate were calculated.

[0169] c. Effect of temperature on adsorption of PM2.5

[0170] Weigh five portions of 2g highland barley straw adsorbent and use mosquito coils to release PM2.5 in a closed box until the mass concentration reaches 500μg / m 3 , set the temperatures to 14℃, 18℃, 22℃, 26℃, and 30℃ respectively, and adsorb for 0.5h, and calculate the adsorption amount and removal rate.

[0171] d. Effect of adsorption time on adsorption of PM2.5

[0172] Weigh five portions of 2g highland barley straw adsorbent and release PM2.5 in a closed box using mosquito coils at room temperature until the mass concentration reaches 500μg / m 3 , adsorb for 20min, 30min, 40min, 50min and 60min respectively, and calculate the adsorption amount and removal rate.

[0173] e. Effect of different initial PM2.5 contents on PM2.5 adsorption

[0174] Weigh five portions of 2g highland barley straw adsorbent respectively, and use mosquito coils to release PM2.5 in a closed box at room temperature, setting the mass concentration of PM2.5 to 300μg / m 3 400 μg / m 3 , 500 μg / m 3 , 600 μg / m 3 , 700 μg / m 3 When the specified initial PM2.5 content value is reached, the highland barley straw adsorbent is placed in a closed box for adsorption for 0.5h, and the adsorption amount and removal rate are calculated.

[0175] Figure 3 5. The figures are as follows: (a) is the effect of the particle size of the highland barley straw adsorbent on the adsorption effect of PM2.5 in Example 1, (b) is the effect of the amount of highland barley straw adsorbent added in Example 1 on the adsorption effect of PM2.5, (c) is the effect of the adsorption temperature of the highland barley straw adsorbent on the adsorption effect of PM2.5, (d) is the effect of the adsorption time of the highland barley straw adsorbent in Example 1 on the adsorption effect of PM2.5, and (e) is the adsorption effect of the highland barley straw adsorbent in Example 1 on PM2.5 at different initial PM2.5 contents.

[0176] Depend on Figure 3 (a) It is concluded that the adsorption effect of highland barley straw adsorbent is best when the particle size is 60 mesh, and the removal rate of PM2.5 reaches 18.45%. F = 3012.575 and P < 0.01. Therefore, the 60-mesh highland barley straw adsorbent adsorbs a fixed amount of PM2.5 in a closed box and reaches adsorption saturation.

[0177] Depend on Figure 3 (b) It is concluded that the adsorption effect of highland barley straw adsorbent is the best when the addition amount is 4g, and the removal rate of PM2.5 reaches 15.82%. F = 1211.951 and P < 0.01. Therefore, adding 4g of highland barley straw adsorbent to adsorb a certain amount of PM2.5 in a closed box with a fixed volume reaches adsorption saturation.

[0178] Depend on Figure 3 (c) It is concluded that the highland barley straw adsorbent has the best adsorption effect when the room temperature is 22℃, and the removal rate of PM2.5 reaches 17.85%. The higher the temperature, the worse the effect. F=756.731 and P<0.01. Therefore, when the indoor temperature is 22℃, the highland barley straw adsorbent can adsorb a certain amount of PM2.5 in a closed box with a fixed volume and reach adsorption saturation.

[0179] Depend on Figure 3 (d) It was concluded that the highland barley straw adsorbent had the best adsorption effect when adsorbed for 50 minutes, and the removal rate of PM2.5 reached 21.32%. F = 955.339 and P < 0.01. Therefore, the highland barley straw adsorbent adsorbed a certain amount of PM2.5 for 50 minutes, and the adsorption of a certain amount of PM2.5 in a closed box with a fixed volume reached adsorption saturation.

[0180] Depend on Figure 3 (e) The initial mass concentration of PM2.5 adsorbed by highland barley straw was 300 μg / m 3 The adsorption effect was the best when the removal rate reached 14.81%. F = 2428.6391 and P < 0.01. Therefore, the highland barley straw adsorbent had a good effect on 300 μg / m 3 PM2.5 reaches adsorption saturation in a closed box with a fixed volume.

[0181] Table 7 Elemental analysis of highland barley straw and highland barley straw adsorbent of Example 1 before and after adsorption

[0182] Materials / Elements N％ C％ H％ S％ Original highland barley straw 0.463 43.180 6.043 0.385 Highland barley straw adsorbent before adsorption 0.335 43.950 6.108 0.214 After adsorption by highland barley straw adsorbent 0.358 44.640 6.198 0.150

[0183] It can be concluded from Table 7 that the highland barley straw adsorbent contains a large amount of C and H elements, followed by a small amount of N and S elements. By comparing the element proportions before and after adsorption, it can be concluded that the elements mainly composed of C and H and some ions have changed, and the highland barley straw adsorbent has ion exchange during the adsorption of PM2.5, proving that the adsorption process of the highland barley straw adsorbent of the present invention is a mixed adsorption combining physics and chemistry.

[0184] Figure 4 The following are scanning electron microscope images of the original highland barley straw and the highland barley straw adsorbent of Example 1 before and after adsorption. Figure 4 (a) is a scanning electron microscope image of the original highland barley straw, (b) is a scanning electron microscope image of the highland barley straw adsorbent in Example 1 before adsorption, and (c) is a scanning electron microscope image of the highland barley straw adsorbent in Example 1 after adsorption. Figure 4 It was concluded that the biggest feature of the original highland barley straw is that there are many surface voids, while the highland barley straw adsorbent has larger surface voids than the original highland barley straw, and the multiple wrinkled textures show the adsorption active sites. These structures provide the highland barley straw adsorbent with the ability to adsorb PM2.5. The voids of the highland barley straw adsorbent decreased after adsorbing PM2.5, proving that the voids were blocked by fine particles. In summary, the highland barley straw adsorbent has more advantages in adsorbing PM2.5.

[0185] Figure 5 The infrared curves of the original highland barley straw and the highland barley straw adsorbent of Example 1 before and after adsorption, (a) is the infrared curve of the original highland barley straw, (b) is the infrared curve of the highland barley straw adsorbent of Example 1 before adsorption, (c) is the infrared curve of the highland barley straw adsorbent of Example 1 after adsorption. The group changes of the original highland barley straw and the highland barley straw adsorbent before and after PM2.5 adsorption were further analyzed by FTIR infrared spectroscopy. Figure 5 (a) It was observed that the stretching vibration of -OH in the original highland barley straw first appeared at 3435.34 cm -1 by Figure 5 (b) It was observed that before the adsorption of highland barley straw adsorbent, the absorption peak formed by -OH stretching vibration was at 3435.19 cm -1 Compared with the original highland barley straw infrared curve image, the hydroxyl group changes, indicating that the -OH in the highland barley straw adsorbent is revealed; Figure 5 (c) It was observed that after the adsorption of highland barley straw adsorbent, the stretching vibration of -OH appeared at 3430.04 cm -1Compared with the original highland barley straw, the vibration intensity of the infrared image of the highland barley straw adsorbent increases.

[0186] A. Adsorption Isotherm

[0187] Common models in adsorption equilibrium are the Langmuir and Freundlich isotherms.

[0188] The Langmuir isotherm is expressed as:

[0189]

[0190] The Freundlich isotherm is expressed as follows:

[0191] q=K·C 1 / n (2)

[0192] Taking the logarithm of both sides of the above equation can turn it into a linear form:

[0193] lgq=lgk+(1 / n)lgC (3)

[0194] Where: C is the equilibrium concentration (μg / m 3 ) ; q is the adsorption amount (μg / g); qm is the saturated adsorption amount (μg / g); b is the adsorption equilibrium constant; k is the Freundhch constant; 1 / n is the adsorption index (n is always greater than 1)

[0195] Figure 6 This is the adsorption effect diagram of highland barley straw adsorbent on PM2.5 at different initial PM2.5 contents in Example 1. At a temperature of 24°C, the adsorption amount q (μg / g) is plotted against the equilibrium concentration C (μg / m 3 ) to draw the adsorption isotherm curve. Figure 6 It was concluded that as the equilibrium concentration of PM2.5 continued to increase, the adsorption of PM2.5 pollutants by highland barley straw adsorbent continued to increase.

[0196] Figure 7 This is the isotherm diagram of PM2.5 adsorption by highland barley straw adsorbent in Example 1. Figure 7 (a) is the Langmuir isotherm diagram of PM2.5 adsorption by highland barley straw adsorbent in Example 1, and (b) is the Freundlich isotherm diagram of PM2.5 adsorption by highland barley straw adsorbent in Example 1. Figure 7(a), (b), combined with Table 9, the correlation coefficient of the Freundlich equation fitting is 0.97, 1 / n is 0.6357, and the data points show good linearity. The correlation coefficient of the Langmuir equation is 0.96, and the data fits well, which fully confirms that the adsorption of PM2.5 by highland barley straw adsorbent conforms to the law given by the Freundlich equation, and the adsorption process is mainly multi-layer adsorption of multiple active sites; using the Langmuir adsorption isotherm, it is calculated that the saturated adsorption capacity of PM2.5 by highland barley straw adsorbent is 11.001μg / g.

[0197] Table 8 Langmuir and Freundlich isotherm parameters of PM2.5 adsorption by highland barley straw in Example 1

[0198]

[0199] B. Adsorption kinetics curve

[0200] Adsorption kinetics is a method of determining the adsorption rate and adsorption mechanism. In the present invention, it is used to describe the adsorption rate of PM2.5 by highland barley straw adsorbent.

[0201] Generally, pseudo-first-order rate equation and pseudo-second-order rate equation are used for quasi-fitting:

[0202] Pseudo-first-order rate equation:

[0203] lg(q e -q t ) = lgq e -k1t / 2.303 (4)

[0204] Pseudo-second-order rate equation:

[0205] t / q t =1 / (k2q e 2 )+t / q e (5)

[0206] Where: q e is the equilibrium adsorption amount (μg / g);

[0207] q t is the pollutant adsorption amount at adsorption time t (μg / g); k1 is the pseudo-first-order adsorption rate constant (min -1 ); k2 is the pseudo-secondary adsorption rate constant (μg·g -1 ·min -1 ) ; t is the adsorption time (min); 1 / n is the adsorption index (n is always greater than 1).

[0208] With t(min) as the horizontal coordinate, q e(μg / g) is used as the ordinate to draw the adsorption kinetics curve.

[0209] 8 is a diagram showing the adsorption effect of highland barley straw adsorbent on PM2.5 at different adsorption times in Example 1. Figure 8 It was found that the adsorption of PM2.5 by highland barley straw adsorbent increased first and then decreased slightly with the extension of time, which proved that highland barley straw adsorbent had a strong binding force for PM2.5. After 24 hours of adsorption, it reached the national safety standard, and the PM2.5 content at this time was 25μg / m 3 .

[0210] Fig. 9 This is a curve diagram of the adsorption rate equation of PM2.5 by highland barley straw adsorbent in Example 1. Fig. 9 (b) is the pseudo-second-order rate equation curve. Fig. 9 (a) and (b) are combined with Table 9 to show that the correlation coefficient of the quasi-second-order kinetic fitting is 0.9776 when the experimental test values ​​are fitted with the two kinetic equations, which is higher than the correlation coefficient of the quasi-first-order kinetic fitting of 0.8641, indicating that the adsorption law of PM2.5 by highland barley straw adsorbent is more consistent with the quasi-second-order kinetic model, and the adsorption process is mainly chemical adsorption.

[0211] Table 9 Example 1 The first and second order kinetic parameters of PM2.5 adsorption by highland barley straw adsorbent

[0212]

[0213] C. Adsorption thermodynamic curve

[0214] Fig.10 The adsorption effect of highland barley straw adsorbent on PM2.5 at different adsorption temperatures in Example 1 is shown in FIG. Fig.10 It was concluded that the adsorption effect was best when the adsorption temperature was 22°C, and the removal rate decreased when it was lower or higher than 22°C. As the adsorption temperature gradually increased, the adsorption amount also reached the maximum value; then, the adsorption amount gradually decreased with the increase of temperature until it reached the lowest point, proving that there is an optimal temperature in the adsorption process.

[0215] The calculation formula for adsorption heat (ΔH) is:

[0216] InK C =△G0 / RT=△S0 / R-△H0 / RT (6)

[0217] K C =ρ1 / ρ2 (7)

[0218] Where: △G0 is the standard Gibbs free energy (KJ / mol); R is the thermodynamic gas constant, the value is J / (mol·K); T is the thermodynamic temperature (K); △H0 is the enthalpy variable of the reaction (KJ / mol); △S0 is the entropy variable [J / (mol·K)]; K C is the thermodynamic equilibrium constant; ρ1 is the mass concentration of PM2.5 gas molecules adsorbed on the adsorbent (μg / m 3 ).

[0219] Table 10 Thermodynamic parameters

[0220] T / K <![CDATA[ΔG0(KJ / mol)]]> <![CDATA[ΔH0(KJ / mol)]]> <![CDATA[ΔS0(J·mol -1 ·K -1 )]]> 14 -5.9828 0.0307 23.0256 18 -6.2025 0.0307 23.0256 22 -6.3785 0.0307 23.0256 26 -6.5102 0.0307 23.0256 30 -6.6872 0.0307 23.0256

[0221] It can be seen from Table 10 that ΔH0>0 and ΔG0<0, which proves that the adsorption process of PM2.5 by highland barley straw adsorbent is a spontaneous endothermic process.

[0222] Fig.11 This is the fitting diagram of the thermodynamic equation for PM2.5 adsorption by highland barley straw adsorbent in Example 1. Fig.11 It is concluded that the correlation coefficient of the fitted thermodynamic curve R 2 It is close to 1, and has a high degree of fit with the thermodynamic equation. This result shows that the adsorption of PM2.5 by the highland barley straw adsorbent in Example 1 conforms to thermodynamics.

[0223] (2) Horizontal comparative analysis

[0224] A. Test groups: Example 1 Highland barley straw adsorbent, original highland barley straw, diatomaceous earth, activated carbon, bamboo charcoal, macroporous resin adsorb PM2.5 and measure the adsorption effect:

[0225] Table 11 Variance analysis table

[0226] Sources of variation SS df MS F P Material 1236.1346 5 247.2269 153.077 0.0001 time 151.5843 4 37.8961 23.4640 0.0001 Material × Time 32.3009 20 1.6150 122.6920 0.0001 error 0.7898 60 0.0132 Total variation 1420.8096 89

[0227] It can be seen from Table 11 that the effects of different materials and different times on the adsorption effect are extremely significant. The combined effect of the two factors significantly affects the adsorption effect of the material on PM2.5.

[0228] Table 12 Effect of different materials on PM2.5 adsorption

[0229] Material Mean α＝0.05 α＝0.01 Example 1 Highland Barley Straw Adsorbent 14.386 a A Activated carbon 7.224 b B diatomite 7.188 b B Bamboo charcoal 6.043 c C Macroporous resin 4.704 d D Original highland barley straw 2.354 e E

[0230] It can be concluded from Table 12 that the adsorption effect of highland barley straw adsorbent in Example 1 on PM2.5 exceeds that of other materials, reaching a very significant level of 1%. Therefore, compared with other adsorbent materials, highland barley straw adsorbent in Example 1 has a significant advantage in the adsorption effect on PM2.5. F test and horizontal comparison show that highland barley straw adsorbent is significantly better than all other materials at a significance level of 1%, diatomaceous earth and activated carbon are second only to highland barley straw adsorbent, and the adsorption effect is comparable, bamboo charcoal is second, and macroporous resin and original highland barley straw have the worst adsorption effect.

[0231] Fig.12 This is a comparison chart of the adsorption effect of different adsorption materials on PM2.5. Fig.12 It was concluded that under the same conditions (temperature 14°C on the day), the highland barley straw adsorbent of Example 1 had the best adsorption effect on PM2.5, which was significantly better than diatomaceous earth, activated carbon, bamboo charcoal, macroporous resin and original highland barley straw.

[0232] (3) Desorption experimental test

[0233] The highland barley straw adsorbent after PM2.5 adsorption was spread out in the sun to dry. After high temperature treatment for 2 hours, the PM2.5 adsorption experiment was repeated. The above steps were repeated for 6 consecutive experiments, and the removal rate was measured each time to further explore its adsorption performance.

[0234] Fig.13 This is the desorption and regeneration diagram of highland barley straw adsorbent in Example 1. Fig.13 It is found that with the increasing number of desorption times, the adsorption effect of each subsequent desorption experiment has a slight decrease. The removal rates of the first five desorption experiments all reached more than 10%, F = 2309.257 and P < 0.01. In summary, although the adsorption capacity of highland barley straw adsorbent has decreased after multiple regenerations, the overall adsorption effect is still considerable and can achieve efficient circulation.

[0235] B. Test group: The highland barley straw adsorbents prepared in Examples 16 to 19 and Comparative Examples 1 to 3 were subjected to adsorption and the adsorption effects were measured:

[0236] Fig.14 The figure is a graph showing the adsorption effect of highland barley straw adsorbent on PM2.5 prepared in Example 1, Example 4 to Example 7 and Comparative Examples 1 to Comparative Examples 3. Fig.14 (a) is a diagram showing the adsorption effect of highland barley straw adsorbent on PM2.5 prepared in Comparative Example 1. Fig.14 (b) is a diagram showing the adsorption effect of the highland barley straw adsorbent prepared in Comparative Example 2 on PM2.5. Fig.14 (c) is a diagram showing the adsorption effect of highland barley straw adsorbents prepared in Examples 16 to 19 on PM2.5. Fig.14(d) is a graph showing the adsorption effect of highland barley straw adsorbent on PM2.5 prepared in Comparative Example 3; Fig.14 (a) It was found that when the NaOH concentration was 0.2 mol / L, the modified highland barley straw had the best PM2.5 removal effect, with a removal rate of 7.83%. However, when the NaOH concentration was 0.5 mol / L, the removal effect was relatively the worst, with a removal rate of only 1.20%. Fig.14 (b) It was found that the removal effect was the best when the citric acid concentration was 0.1 mol / L and the hemicellulase concentration was 0.1 mg / mL, with a removal rate of 3.69%, while the removal effect was relatively the worst when the cellulase concentration was 0.3 mg / mL, with a removal rate of only 0.10%. Fig.14 (c) It was concluded that, with a fixed concentration of 0.15 mol / L of ethyl acetate, the removal effect was best when the cellulase concentration was 0.4 mg / mL, with a removal rate of 11.91%. The removal effect was relatively poor when the cellulase concentration was 0.5 mg / ml, with a removal rate of only 0.80%. Fig.14 (d) It was concluded that, when the concentration of lignin peroxidase was 12 mg / mL and the KCl concentration was fixed at 0.15 mol / L, the removal effect was the best, with a removal rate of 6.52%. However, when the concentration of lignin peroxidase was 16 mg / mL, the removal effect was relatively the worst, with a removal rate of only 0.30%.

[0237] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0238] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a highland barley straw adsorbent, characterized in that: The following steps are involved: The highland barley straw is placed in an ester compound aqueous solution for esterification treatment to remove protein and oil components in the highland barley straw to obtain esterified highland barley straw; placing the esterified highland barley straw in a cellulase solution for enzymolysis treatment to obtain enzymolyzed highland barley straw; The enzymatically hydrolyzed highland barley straw is subjected to enzyme inactivation treatment, dried and crushed to obtain a highland barley straw adsorbent.

2. The method for preparing the highland barley straw adsorbent according to claim 1, characterized in that: The method of esterification treatment is: soaking highland barley straw in an aqueous solution of ester compounds for 17.3 hours to 30.7 hours.

3. The method for preparing the highland barley straw adsorbent according to claim 1, characterized in that: In the aqueous solution of ester compounds, the ester compound is selected from one of ethyl acetate, butyl acetate, amyl acetate, hexyl acetate, heptyl acetate, octyl acetate, isoamyl acetate or isooctyl acetate, and the concentration of the aqueous solution of ester compounds is 0.07 mol / L to 0.23 mol / L.

4. The method for preparing the highland barley straw adsorbent according to claim 1, characterized in that: The mass concentration of the cellulase solution in the enzymatic hydrolysis treatment is 0.1 mg / mL to 0.5 mg / mL.

5. The method for preparing the highland barley straw adsorbent according to claim 1, characterized in that: The highland barley straw was also cooked before esterification.

6. A highland barley straw adsorbent prepared by the preparation method according to any one of claims 1 to 5.

7. The highland barley straw adsorbent according to claim 6, characterized in that: The particle size of the highland barley straw adsorbent is 18-100 meshes.

8. Use of the highland barley straw adsorbent according to claim 6 or 7 in the preparation of PM2.5 adsorbent.

9. The use of highland barley straw adsorbent in preparing PM2.5 adsorbent according to claim 8, characterized in that: The highland barley straw adsorbent is placed in an air atmosphere containing PM2.5 for adsorption treatment.

10. The use of highland barley straw adsorbent in preparing PM2.5 adsorbent according to claim 8, characterized in that: The ratio of the mass of highland barley straw adsorbent to the amount of PM2.5 is 1g~5g:300μg / m 3 ~700 μg / m 3 .

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