Suaeda glauca adsorbent as well as preparation method and application thereof

Abstract

The invention discloses a suaeda glauca adsorbent as well as a preparation method and application thereof, and belongs to the technical field of air purification. The suaeda glauca adsorbent for adsorbing PM10 is obtained by modifying suaeda glauca through a citric acid-assisted double-enzyme method, the preparation method provided by the invention is simple, the materials are easy to obtain, the production cost is low, and compared with adsorption materials such as activated carbon, diatomite and resin in the prior art, the adsorption efficiency is greatly improved. The suaeda glauca adsorbent provided by the invention has a better adsorption effect on PM10, is economical and environment-friendly, and has an excellent industrial prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of air purification, and particularly relates to a Suaeda salsa adsorbent and a preparation method and application thereof. Background Art

[0002] Suaeda glauca Bunge is a plant of the genus Suaeda of the family Leucaceae. The tender seedlings are commonly known as "wolf tail strips", often called sea wormwood, alkali wormwood, salt wormwood, etc., and are also known as tiger tail, monk head, pig tail, and are called salty wormwood in Yuncheng Salt Lake. It is an annual herbaceous plant of the genus Suaeda of the family Chenopodiaceae. Suaeda glauca Bunge likes high humidity, is salt-alkali tolerant, tolerant to barrenness, and has few diseases and insect pests. It is a natural pollution-free green food. It not only has good commercial value, but also has a beautiful plant shape. It is tender green when it is born and fiery red when mature. It is very ornamental and has the elegant name of "emerald coral". It is used as an ornamental plant. Suaeda glauca Bunge is a treasure from head to toe. The tender stems and leaves of Suaeda glauca can be eaten fresh or made into stems, which is convenient for storage and transportation. Therefore, Suaeda glauca Bunge has good prospects in tourism, food and medicine development. Planting it in gardens is conducive to the restoration of the natural ecological environment and is very ornamental. It is also low in cost and wide in source, and will not cause secondary pollution. One of the important directions of ecological governance in the future is to focus on the restoration of salt-land salsa phytoremediation, while supplemented by other biological, physical, chemical and other ecological restoration technologies to jointly improve the effect and efficiency of ecological restoration. This comprehensive restoration method helps to achieve the stability and sustainable development of ecological restoration and promote the virtuous cycle of the ecological environment. However, after most of the salsa phytoremediation plants withered, they were burned in large quantities by humans, causing environmental pollution.

[0003] PM 10 PM is a type of inhalable particulate matter with a particle size of less than or equal to 10 microns, which is one of the air pollutants. 10 The concentration is usually expressed in micrograms per cubic meter. The higher the content in the environment, the more serious the air pollution is. Domestic and foreign studies have shown that air pollution not only reduces atmospheric visibility, but also causes various respiratory diseases. Short-term exposure to air pollutants will increase the number of visits to the respiratory and circulatory systems, and increase the incidence of diseases, respiratory and cardiovascular diseases, and mortality. 10 The higher the concentration, the greater the risk of tuberculosis. 10 Common sources of PM2.5 include emissions from motor vehicles traveling on roads not paved with asphalt or cement, particulate matter generated during material crushing, grinding and other processing processes, and dust blown by the wind. These particulate matter have an impact on air quality and human health that cannot be ignored. Indoors, secondhand smoke is the main source of particulate matter. PM2.5 10 Due to their small diameter, particulate matter can easily enter the respiratory tract through breathing. Although some of it can be discharged out of the body through spitting, sneezing, etc., it still has a certain impact on human health.

[0004] Biosorbents have low manufacturing costs, high removal rates, and are easy to regenerate and recycle. Biosorbents have broad prospects and diverse research methods. In particular, there have been many studies on biosorbents for the adsorption and treatment of heavy metals in water bodies, but there are still some potential problems. The purpose of research has always been to prepare biosorbents with large adsorption capacity, fast adsorption speed, and efficient recycling. Most of the research on biosorbents for the adsorption of polluted gases is based on biochar. Although the modification and preparation of biochar adsorbents in various countries around the world have achieved certain success, most of them are still in the laboratory environment stage. Biosorbents have great prospects for the adsorption of gases, waiting to be explored.

[0005] Currently, for PM 10 The main method of purification is still to use air conditioning filtration technology, but the cost of the required materials is too high, the initial resistance of the materials is large, which affects the air volume of the air conditioner, resulting in the air conditioner performance not meeting the requirements. 10 The adsorption performance can achieve low-cost, green and healthy adsorption of harmful gases, making Suaeda salsa have a good development prospect in terms of adsorption performance. Summary of the invention

[0006] In view of the above-mentioned prior art, the present invention provides a Suaeda salsa grass adsorbent and a preparation method and application thereof, which solves the problem of a large amount of Suaeda salsa grass being discarded and modifies it into a biological adsorbent.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing a Suaeda salsa adsorbent, comprising the following steps:

[0008] S1: mixing a cellulase solution and an acidic protease solution, and adding a citric acid solution thereto to adjust the pH to 4.0 to obtain a mixed enzyme solution;

[0009] S2: Soak the cleaned Suaeda salsa in the mixed enzyme solution and then place in a water bath at 45-55°C for 30 minutes;

[0010] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0011] S4: The crude product is washed to neutrality, dried and crushed to obtain the Suaeda salsa adsorbent.

[0012] The beneficial effect of the present invention is that the present invention modifies the alkali grass by means of citric acid-assisted dual enzymes, so that the pore structure on the surface of the alkali grass becomes more and the overall surface is rougher. This structure can provide more implantation sites for the adsorption process and the adsorption effect is better, and finally a biosorbent with excellent adsorption effect is obtained. The preparation process is simple and easy, the production cost is low, and it has excellent industrial prospects.

[0013] Based on the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, the concentration of the mixed enzyme solution is 0.1-0.5 g / L, and the mass ratio of cellulase to acid protease in the mixed enzyme solution is 1-5:1-5.

[0015] Furthermore, the concentration of the mixed enzyme solution was 0.3 g / L, and the mass ratio of cellulase to acid protease in the mixed enzyme solution was 1:3.

[0016] The beneficial effect of adopting the further technical solution is that a reasonable reagent ratio is used to make the final product have excellent technical effects.

[0017] Furthermore, the concentration of the citric acid solution was 0.1 mol / L.

[0018] Furthermore, the drying treatment is carried out in a forced air drying oven at 80-90° C. to a constant weight.

[0019] The invention also discloses a preparation method of the Suaeda salsa grass adsorbent and the prepared Suaeda salsa grass adsorbent.

[0020] The invention also discloses a method for adsorbing PM2. 10 Application in.

[0021] The beneficial effect of the present invention is that the present invention uses citric acid to assist the double enzyme method to modify the alkali grass and then use it to absorb PM 10 , with the existing PM 10 Compared with the purification and filtration technology, the Suaeda salsa grass adsorbent provided by the present invention has better adsorption effect, low preparation cost and easy-to-obtain materials, which makes it more cost-effective in the competition with the existing technology products and also makes the biological adsorbent more promising. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The Suaeda salsa adsorbent prepared in Examples 1 to 5 adsorbs PM 10 Statistical chart of the effect;

[0023] Figure 2 This is the effect of cellulase concentration and water bath time on removal rate;

[0024] Figure 3 Effect of particle size of slag on PM adsorption of Suaeda salsa adsorbent prepared under optimized conditions in Experimental Example 2 10 Statistical chart of the effect;

[0025] Figure 4 Effect of the amount of Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 on the adsorption of PM 10 Statistical chart of the effect;

[0026] Figure 5 The effect of temperature on PM adsorption 10 Statistical chart of the effect;

[0027] Figure 6 For PM 10 Effect of initial concentration on adsorption of PM 10 Statistical chart of the effect;

[0028] Figure 7 is the adsorption time on PM 10 Statistical chart of the effect;

[0029] Figure 8 For PM 10 The relationship between initial concentration and adsorption amount;

[0030] Fig. 9 The Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 was effective in adsorbing PM 10 Langmuir model;

[0031] Fig.10 The Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 was effective in adsorbing PM 10 Freundich model;

[0032] Fig.11 It is the relationship diagram between adsorption time and adsorption amount;

[0033] Fig.12 The pseudo-first-order adsorption kinetic curves of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 at different times;

[0034] Fig.13 The quasi-secondary adsorption kinetic curves of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 at different times;

[0035] Fig.14 is the relationship between adsorption temperature and adsorption amount;

[0036] Fig.15 This is a thermodynamic analysis equation diagram of the Suaeda salsa adsorbent obtained under the optimized conditions of Experimental Example 2;

[0037] Fig.16 is the infrared spectrum;

[0038] Fig.17 This is the SEM image of the original Suaeda salsa;

[0039] Fig.18 This is the SEM image of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2;

[0040] Fig.19 To adsorb PM 10SEM image of the Suaeda salsa adsorbent after treatment;

[0041] Fig. 20 Six adsorption materials for PM 10 Comparison chart of the impact effects;

[0042] Fig.21 This is the desorption recovery analysis diagram of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2. DETAILED DESCRIPTION

[0043] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0044] Example 1

[0045] A method for preparing a Suaeda salsa adsorbent comprises the following steps:

[0046] S1: mixing a cellulase solution and an acidic protease solution, and adding 0.1 mol / L citric acid solution thereto to adjust the pH to 4.0, to obtain a mixed enzyme solution (concentration 0.1 g / L, mass ratio of cellulase to acidic protease is 1:1);

[0047] S2: Soak the cleaned Suaeda salsa in an acidic mixed enzyme solution and then in a 50°C water bath for 30 minutes;

[0048] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0049] S4: The crude product is washed to neutrality, dried in a forced air drying oven at 80°C to constant weight, and then crushed to obtain the Suaeda salsa adsorbent.

[0050] Example 2

[0051] S1: mixing a cellulase solution and an acidic protease solution, and adding 0.1 mol / L citric acid solution thereto to adjust the pH to 4.0, to obtain a mixed enzyme solution (concentration 0.2 g / L, mass ratio of cellulase to acidic protease 5:1);

[0052] S2: Soak the cleaned Suaeda salsa in an acidic mixed enzyme solution and then in a 45°C water bath for 30 minutes;

[0053] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0054] S4: The crude product is washed to neutrality, dried in a forced air drying oven at 85°C to constant weight, and then crushed to obtain the Suaeda salsa adsorbent.

[0055] Example 3

[0056] S1: mixing a cellulase solution and an acidic protease solution, and adding 0.1 mol / L citric acid solution thereto to adjust the pH to 4.0, to obtain a mixed enzyme solution (concentration 0.3 g / L, mass ratio of cellulase to acidic protease 1:3);

[0057] S2: Soak the cleaned Suaeda salsa in an acidic mixed enzyme solution and then in a 55°C water bath for 30 minutes;

[0058] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0059] S4: The crude product is washed to neutrality, dried in a forced air drying oven at 90°C to constant weight, and then crushed to obtain the Suaeda salsa adsorbent.

[0060] Example 4

[0061] S1: mixing the cellulase solution and the acidic protease solution, and adding 0.1 mol / L citric acid solution thereto to adjust the pH to 4.0, to obtain a mixed enzyme solution (concentration 0.4 g / L, mass ratio of cellulase to acidic protease 2:3);

[0062] S2: Soak the cleaned Suaeda salsa in an acidic mixed enzyme solution and then in a 50°C water bath for 30 minutes;

[0063] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0064] S4: The crude product is washed to neutrality, dried in a forced air drying oven at 80°C to constant weight, and then crushed to obtain the Suaeda salsa adsorbent.

[0065] Example 5

[0066] S1: mixing a cellulase solution and an acidic protease solution, and adding 0.1 mol / L citric acid solution thereto to adjust the pH to 4.0, to obtain a mixed enzyme solution (concentration 0.5 g / L, mass ratio of cellulase to acidic protease 1:5);

[0067] S2: Soak the cleaned Suaeda salsa in an acidic mixed enzyme solution and then in a 50°C water bath for 30 minutes;

[0068] S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product;

[0069] S4: The crude product is washed to neutrality, dried in a forced air drying oven at 80°C to constant weight, and then crushed to obtain the Suaeda salsa adsorbent.

[0070] Experimental Example 1

[0071] PM 10Adsorption test: Place the air quality detector in 5 plastic wrap sealed boxes with a length, width and height of 40 cm respectively, and mark a fixed position in each box to place the Suaeda salsa adsorbent. Light the mosquito coil and let it stand for 20 seconds, then extinguish it and quickly take out the mosquito coil to ensure that the box is quickly closed to simulate a PM 10 Indoor air environment exceeds the standard. Wait until the gas in the box is evenly diffused and the value stabilizes to 500ug / m 3 ±5ug / m 3 Then, 2 g of the Suaeda salsa adsorbent prepared in Examples 1 to 5 was placed in 5 boxes respectively, and the formaldehyde concentration in the boxes was detected again after 30 minutes.

[0072] Suaeda salsa adsorbent for PM 10 The calculation formula of the removal rate N is:

[0073] N = (C0-C) × 100% / C0-P,

[0074] Suaeda salsa adsorbent for PM 10 The calculation formula of the adsorption amount q is:

[0075] q=(C0-C)×V / M,

[0076] Where q is the adsorption amount (μg / g), C0 is the PM in the sealed box 10 The initial concentration of PM2.5 was 2.377 million, and C was the initial concentration of PM2.577 million after adsorption by Suaeda salsa adsorbent in the sealed box. 10 The equilibrium concentration (μg / m 3 ), V is the volume of the sealed box (m 3 ), M is the amount of Suaeda salsa adsorbent added (g), and P is the leakage rate of the sealed box.

[0077] The calculation formula of the sealing box leakage rate is:

[0078] P = (n0-n) / n0,

[0079] Where n0 is the fixed value reached by the air quality detector, and n is the reading of the air quality detector without adding the Suaeda salsa adsorbent but after the expected removal time.

[0080] The experimental results are as follows Figure 1 As shown, the Suaeda salsa adsorbent adsorbs PM 10 The removal capacity will first increase and then decrease with the increase of the concentration of the dual enzyme solution. When the dual enzyme concentration is 0.3g / L, the removal rate is as high as 18.55%.

[0081] Experimental Example 2

[0082] Optimization experiment: The treatment method of Suaeda salsa adsorbent was optimized by quadratic orthogonal rotation regression combined experimental design. The experimental data were analyzed by DPS software, and the concentration of cellulase, the concentration of acid protease, and the water bath time were selected as the key factors affecting the removal rate of Suaeda salsa adsorbent. The factor level coding table was compiled as shown in Table 1, and then the quadratic orthogonal rotation regression combined experimental design table was drawn according to Table 1, as shown in Table 2. The Suaeda salsa adsorbent was optimized and prepared according to the technical parameters in Table 2.

[0083] Table 1 Factor level coding table

[0084]

[0085]

[0086] Table 2 Quadratic orthogonal rotation regression combination experimental design table

[0087]

[0088] After the removal rate of the optimized Suaeda salsa adsorbent prepared according to Table 2 was measured using the method of Experimental Example 1, a variance analysis was performed on the removal rate. The results are shown in Table 3.

[0089] Table 3 ANOVA table

[0090]

[0091]

[0092] From Table 3, we can see that X2 is extremely significant at the 1% level of difference F1, and X1X3 is significant at the 5% level. According to the DPS software analysis, the following model regression equation is obtained: Y = 9.09054 + 0.11037X1 + 0.43444X 2+ 0.00463X3+0.07534X1 2 +0.29985X2 2 +0.03469X3 2 +0.18250X1X2+0.42000X1X3-0.18750X2X3.

[0093] At a significant level of 0.01, the F 失拟 =2.575 <F 0.01(5,8) =6.63, indicating that the experimental error is very small and all unknown factors have been taken into account in the experimental design; F 回归 =4.540>F 0.01(9,13) =4.19, indicating that the regression equation is extremely significant, the experimental speculation is extremely reliable, the prediction is accurate, and the model is established.

[0094] The regression was tested for significance. After removing the insignificant items at the α=0.10 level, a quadratic analysis of variance was performed (Table 4). The simplified regression equation was: Y=9.09054+0.43444X2+0.29985X2 2 +0.42000X1X3.

[0095] Table 4 Quadratic ANOVA table

[0096] Sources of variation Sum of Squares (SS) Degrees of freedom (df) Mean square (MS) Ratio F P-value <![CDATA[X2]]> 2.5776 1 2.5776 16.8975 0.0012 <![CDATA[X22]]> 1.4216 1 1.4216 9.319 0.0093 <![CDATA[X1X3]]> 1.4112 1 1.4112 9.2511 0.0095 return 6.2335 9 0.6926 <![CDATA[F2=4.540]]> 0.0144 Remaining 1.9831 13 0.1525 sum 8.2165 22

[0097] From the first-order variance analysis table, it can be seen that the interactions between the three factors (X1, X2, and X3) will affect the adsorption effect. Compared with the interactions between X1X2 and X2X3, the X1X3 interaction is significant, that is, the concentration (g / L) of cellulase and the water bath time (min) have a significant effect on the adsorption effect. The effects of the interaction between X1X3 are shown in Table 5. The 3D diagram of the interaction relationship between X1X3 is shown in Table 5. Figure 2 .

[0098] Table 5 Effect of cellulase concentration and water bath time on adsorption effect

[0099]

[0100] When the water bath time is constant, if the cellulase concentration increases, the adsorption capacity of the Suaeda salsa adsorbent will decrease with the increase of water bath time; when the cellulase concentration is fixed, the adsorption capacity of the Suaeda salsa adsorbent will increase with the increase of water bath time. Figure 2 It can be seen that the highest point (-1.682, -1.682) is when the cellulase concentration is 0.07 g / L, the water bath time is 20 min, and the maximum removal rate is 10.28%.

[0101] In summary, the DPS data processing system shows that PM adsorption 10 Among the three factors, the best adsorption combination is (-1.682, 1.682, -1.682). Under this combination, the cellulase concentration is 0.07 g / L, the acid protease concentration is 0.23 g / L, and the water bath time is 20 min. At this time, the removal rate reaches the highest value of 11.86%. According to this combination, the optimal residue is prepared to detect the adsorption of PM by Suaeda salsa residue. 10 The removal rate was 11.84% after three repeated experiments. The actual measured value / software predicted value = 0.998, which is close to 1, indicating that the results are reliable and the model is correct.

[0102] Experimental Example 3

[0103] Single factor experiment: This experiment was conducted with five factors: initial concentration, removal time, optimized amount of Suaeda salsa adsorbent, removal temperature, and particle size of Suaeda salsa adsorbent residue, to explore the effect of each factor on PM 10 The influence of adsorption effect.

[0104] 1. Particle size test of Suaeda salsa adsorbent residue: The Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 was crushed using a high-speed crusher, and then sieved through sieves of different mesh sizes (18 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh) to obtain modified residues of different particle sizes. Accurately weigh 2g of modified residues of different mesh sizes and put them into PM 10 The concentration is 500 μg / m 3 After 30 minutes of adsorption, record the PM 10 The concentration changes were calculated based on the modified Suaeda salsa residue with different mesh sizes on PM 10 The experimental results are as follows: Figure 3 As shown in the figure, the adsorption capacity of Suaeda salsa adsorbent increases first and then decreases with the increase of slag particle size. In this experiment, the mesh size changes from 18 mesh to 100 mesh. In the change from 18 mesh to 40 mesh, the adsorption effect increases with the increase of mesh size, and the adsorption amount decreases with the increase of slag particle size. When the mesh size reaches 40 mesh, the removal rate is the highest (F=763.144, P<0.01), but when the slag particle size is smaller than 40 mesh, the removal rate begins to decrease, so the slag particle size of the optimal slag in this experiment is 40 mesh, and the removal rate is 12.92%.

[0105] 2. Adsorbent addition test: Weigh 1g, 1.5g, 2g, 2.5g, and 3g of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 respectively. 10 The concentration was maintained at 500 μg / m 3 When the slag particles are placed in a sealed box for adsorption for 30 minutes, the removal rate is calculated. Figure 4 As shown, the adsorption capacity of Suaeda salsa adsorbent shows a trend of first increasing and then decreasing with the increase of the added amount. This experiment was set with a gradient change in grams from 1g to 3g. In the change from 1g to 3g, the adsorption effect increased with the increase of the added amount, and the adsorption amount also increased accordingly; when the gram amount reached 2g, the removal rate was the highest, and the adsorption amount was also the highest (F=227.421, P<0.01); but when the added amount was more, the removal rate began to decrease, and the adsorption amount also decreased, so the optimal added amount of this experiment was 2g, and the removal rate was 11.76%.

[0106] 3. Temperature test: The adsorption temperature was set to a temperature gradient of 22°C, 24°C, 26°C, 28°C, and 30°C. 2 g of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 was weighed. PM10 The initial concentration was 500 μg / m 3 The adsorption of PM by Suaeda salsa adsorbent at different temperatures was calculated. 10 The experimental results are as follows: Figure 5 As shown, the Suaeda salsa adsorbent adsorbs PM 10 The removal rate of PM2.5 increased gradually with the increase of temperature. When the temperature reached 30℃, the adsorption effect was the best, with a removal rate of 11.84% (F=385.887, P<0.01). 10 The adsorption amount increases slowly and tends to be moderate, indicating that the adsorption process is affected by temperature to a certain extent.

[0107] 4. PM 10 Initial concentration test: Weigh 2g of Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 and wait for the PM 10 The concentration reached 400, 450, 500, 550, 600 μg / m 3 When the slag particles are placed in a sealed box for adsorption for 30 minutes, the removal rate is calculated. Figure 6 As shown in the figure, the adsorption capacity of Suaeda salsa adsorbent increases with the increase of initial concentration. This experiment was set from 400ug / m 3 ~600ug / m 3 The concentration gradient changes, when the concentration is 600ug / m 3 , and its removal rate was the highest, which was 12.83% (F=331.13, P<0.01).

[0108] 5. Adsorption time test: Weigh 2g of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 and wait for the PM 10 The concentration reached 500 μg / m 3 At different time points, 30min, 60min, 90min, 120min and 150min, the Suaeda salsa adsorbent was placed in a sealed box for removal experiments. At each set time point, the PM in the sealed box was accurately measured and recorded. 10 The concentration change was calculated to determine the removal rate at the corresponding time point. Figure 7 As shown, the adsorption capacity of the Suaeda salsa adsorbent shows an increasing trend with the increase of time. The experiment was set with a time gradient from 30min to 150min. In the change from 30min to 150min, the adsorption effect increased with the increase of time; at 150min, the removal rate was the highest, with a removal rate of 13.07% (F=138.452, P<0.01).

[0109] Experimental Example 4

[0110] Adsorption isotherm experiment: This experiment uses the Langmuir isotherm and Freundlich isotherm to describe the adsorption of Suaeda salsa adsorbent and PM 10 The relationship between the initial concentration.

[0111] The Langmuir isotherm is:

[0112] C / Q=C / Q m +1 / Q m b,

[0113] The Freundlich isotherm is:

[0114] Q=K×C n ,

[0115] Taking the logarithm of both sides of the Freundlich isotherm can be converted into a linear form:

[0116] IgK+(1 / n)IgC=IgQ

[0117] Where C is the equilibrium concentration (mg / L), Q is the equilibrium adsorption amount (mg / g), and Q m is the saturated adsorption capacity (mg / g), b is the adsorption equilibrium constant, and K and n are constants at a certain temperature.

[0118] The equilibrium adsorption amount calculation formula is:

[0119] Q=(C0-C)V / m,

[0120] Where C0 is the initial concentration (mg / m 3 ); V is the volume of the closed box (m 3 ); m is the mass of the adsorbent (g).

[0121] Take five closed boxes of the same size, numbered 1, 2, 3, 4, and 5, and light cigarettes in each of them. 10 The concentrations were stable at 400 μg / m 3 450 μg / m 3 , 500 μg / m 3 , 550μg / m 3 and 600 μg / m 3 2 g of Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 was evenly placed in each box (to ensure that the adsorbent was evenly distributed in the culture dish). After 30 minutes of adsorption, the PM in each sealed box was measured in turn. 10 The concentration of PM 10 The adsorption amount was then fitted using the above two adsorption isotherm models.

[0122] PM10 The relationship between initial concentration and adsorption amount is as follows: Figure 8 As shown, the Langmuir model is Fig. 9 As shown, the Freundlich model is Fig.10 As shown in Table 6, according to the adsorption isotherm model parameter table, the Freundlich isotherm model fitting correlation coefficient R 2 is closer to 1, proving that the modified Suaeda salsa can adsorb PM 10 The process belongs to multi-molecular layer site adsorption.

[0123] Table 6 Adsorption isotherm model parameters

[0124]

[0125] Experimental Example 5

[0126] Adsorption kinetics experiment: When the initial concentration is the same, the adsorption effect of Suaeda salsa adsorbent on PM10 under five time gradients is fitted using pseudo-first-order kinetics and pseudo-second-order kinetics models.

[0127] Take a closed box, light a cigarette in it, and when the concentration of PM10 is constant at 500μg / m3, put in 2g of Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 (evenly spread in the culture dish), then measure it every 30 minutes, record the concentration of PM10, and calculate the adsorption amount after different time, draw the adsorption kinetic curve, and fit it to the pseudo-first-order kinetic equation and pseudo-second-order kinetic equation respectively to explore its adsorption mechanism.

[0128] The pseudo-first-order dynamic equation is expressed as:

[0129] Ig(Qq)=IgQ-k1t / 2.303,

[0130] The pseudo-second-order dynamic equation is expressed as:

[0131] t / q=1 / (k2×Q)+t / Q,

[0132] Q is the equilibrium adsorption amount (mg / g), q is the adsorption amount at adsorption time t (mg / g), k1 is the first-order adsorption rate constant (g·mg -1 ·min -1 ), k2 is the secondary adsorption rate constant (g·mg -1 ·min -1 ).

[0133] The experimental results are as follows Figures 11 to 13 As shown, Fig.11 The adsorption of PM at different adsorption times 10The effect of adsorption is shown in Figure 2. On this basis, the quasi-first-order adsorption kinetic curve ( Fig.12 ), and then plotting the quasi-secondary adsorption kinetic curve with the horizontal and vertical coordinates t and (t / q) ( Fig.13 ), and thus the adsorption dynamic parameter table (Table 7) was obtained. Through the chart analysis, it can be seen that the Suaeda salsa adsorbent adsorbs PM 10 The correlation coefficient R between the data and the pseudo-second-order kinetic model 2 It reaches 0.9706, which is closer to 1, indicating that the adsorption process follows the law of the pseudo-second-order kinetic model. The experimental process is mainly based on chemical adsorption and supplemented by physical adsorption.

[0134] Table 7 Adsorption dynamic parameters

[0135]

[0136] Experimental Example 6

[0137] Adsorption heat experiment: Thermodynamic analysis was performed on the Suaeda salsa adsorbent obtained under the optimized conditions of Experimental Example 2. The calculation formula for adsorption heat is:

[0138] InK c =-ΔG0 / RT=-ΔH0 / RT+ΔS0 / R,

[0139] K c =q / c,

[0140] Among them, △G0 refers to the standard Gibbs free energy, the unit is kJ / mol; R refers to the thermodynamic gas constant, the value is 8.314J / (mol·K); T is the thermodynamic temperature, the unit is K; △H0 is the enthalpy variable of the reaction, the unit is kJ / mol; △S0 is the entropy variable, the unit is J / (mol·K); K C is the thermodynamic equilibrium constant.

[0141] The temperature test shows that the Suaeda salsa adsorbent adsorbs PM 10 The removal rate of PM2.5 increased with the increase of temperature. When the temperature reached 30℃, the adsorption effect was the best, with a removal rate of 11.84%. 10 The adsorption amount of Suaeda salsa L. adsorbent on PM in the temperature test was calculated. 10 The adsorption amount of Fig.14 As shown in Table 8, △H0>0, so the adsorption process is an endothermic process, and △G0<0, indicating that the adsorption process occurs spontaneously. Then, the thermodynamic curve is drawn according to the adsorption results, as shown in Fig.15 It can be seen that the influence of temperature on the adsorption amount and the correlation coefficient R of the thermodynamic curve fitting 2It is close to 1, indicating that the process conforms to the laws of thermodynamics.

[0142] Table 8 Thermodynamic parameters

[0143] T / K <![CDATA[ΔG0(KJ / mol)]]> <![CDATA[ΔH0(KJ / mol)]]> <![CDATA[ΔS0(J·mol -1 ·K -1 )]]> 295 -5.8388 3.4098 31.6273 297 -5.9111 3.4098 31.6273 299 -5.9570 3.4098 31.6273 301 -6.0216 3.4098 31.6273 303 -6.1000 3.4098 31.6273

[0144] Experimental Example 7

[0145] FTIR analysis experiment: Fourier transform infrared spectroscopy was used to analyze the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2, the original Suaeda salsa and the PM adsorbed 10 The alkali grass adsorbent was analyzed and the experimental results are as follows Fig.16 As shown, a is the adsorption of PM 10 b is the Suaeda salsa grass adsorbent obtained under the optimized conditions of Experimental Example 2, and c is the original Suaeda salsa grass. According to the infrared spectrum, it can be seen that:

[0146] (1) At wave number 3401 cm -1 , 3407cm -1 , 3410cm -1 There is an obvious absorption peak, which means that the molecules of Suaeda salsa contain a large amount of -OH. 10 The intensity of the absorption peak of the Suaeda salsa adsorbent changed significantly after the treatment, indicating that the citric acid-assisted dual enzyme treatment affected the number and activity of -OH in the Suaeda salsa material, and that the free -OH played a significant role in the adsorption process. -1 With 1400cm -1 There are three absorption peaks of unequal intensity on the left and right. This is a special absorption peak containing -OH in the molecule.

[0147] (2) At a wave number of 2920 cm -1 Nearby is the absorption peak of CH. From the changes in the three lines, it can be analyzed that the CH group also plays a certain role in the adsorption process.

[0148] (3) At wave number 1739 cm -1 At the wave number of 1642cm-1, -C=O stretching vibration absorption occurs, which plays a certain role in participating in the reaction during the adsorption process; at the wave number of 1642cm-1, an absorption peak of the C=N group appears, and stretching vibration absorption occurs. The transmittance of this absorption peak gradually increases after modification and absorption, proving that this group also participates in the reaction during the adsorption process.

[0149] (4) at 1244 cm -1 There is a -COC- group at the wavenumber around 2.5 to participate in the adsorption reaction.

[0150] (5)1046cm -1 is the CO stretching vibration absorption peak, and at 611cm -1Near the fingerprint region are the stretching vibration peaks of CC and CH, which also participate in the adsorption process.

[0151] In summary: the above functional groups play different roles in the adsorption reaction process, and hydroxyl plays a decisive role, which proves that this adsorption is a chemical-dominated adsorption process.

[0152] Experimental Example 8

[0153] SEM characterization and analysis experiment: Scanning electron microscopy was used to characterize the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2, the original Suaeda salsa, and the PM adsorbed 10 The alkali grass adsorbent was analyzed and the experimental results are as follows Figures 17 to 19 As shown, Fig.17 It can be seen that compared with the original Suaeda salsa, the pore structure has become more and the overall surface is rougher. This structure can provide more implantation sites for the adsorption process, and the adsorption effect is better. Fig.18 It can be seen that since Suaeda salsa is composed of a large amount of cellulose and hemicellulose, its microscopic morphological structure is loose and porous. Fig.19 It can be seen that the overall surface is smoother than the original and modified non-adsorbed ones, which is due to the fact that the loose microporous structure is filled with the adsorbed substances during the adsorption process.

[0154] Experimental Example 9

[0155] Elemental analysis: Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2, original Suaeda salsa and PM adsorbed 10 The elemental analysis of the alkali grass adsorbent was performed, and the experimental results are shown in Table 9. The original alkali grass contains a large amount of C and H elements, and the S element content is the least. By comparing with the original alkali grass, the C element is slightly reduced after citric acid-assisted double enzyme treatment, and other elements are also slightly reduced. After adsorption, all elements have increased. After alkali blanching treatment, the N element is significantly reduced, the C element is significantly increased, and the H and S elements do not change significantly. After adsorption, the C element is significantly reduced, indicating that the modification treatment may change the number of -COOH, -C=N, -OH and other groups, which has an impact on the adsorption of PM 10 Play a major role.

[0156] Table 9 Elemental analysis table

[0157]

[0158] Experimental Example 10

[0159] BET analysis: Through the BET test, the specific surface area, pore volume, etc. of the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 were measured to obtain the specific surface area parameters of the material to analyze the physical structure of the Suaeda salsa adsorbent. The experimental results are shown in Table 10. The larger pore size on the surface of the Suaeda salsa adsorbent can provide adsorption sites.

[0160] Table 10 BET parameter analysis table

[0161] Test items Measurements <![CDATA[Specific surface area (m 2 / g)]]> 2.098 <![CDATA[Pore volume (cm 3 / g)]]> 0.005 Pore ​​size distribution (d) 1.936

[0162] Experimental Example 11

[0163] Horizontal comparison experiment: Take the Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 and the original Suaeda salsa, bamboo charcoal, macroporous resin, activated carbon and diatomaceous earth for adsorption test. Take 1g of each adsorption material and set the adsorption time gradient to 30min, 60min, 90min, 120min, 150min. Set the same PM 10 The experiment was carried out with different concentrations to calculate the actual removal rate and compare the adsorption effect. Fig. 20 As shown, optimized Suaeda salsa adsorbent > activated carbon > diatomaceous earth > bamboo charcoal > macroporous resin > original Suaeda salsa. The optimized Suaeda salsa adsorbent has the highest removal rate, and the original Suaeda salsa has the lowest removal rate. The removal rate of Suaeda salsa adsorbent is higher than that of the other four materials, and the cost is the lowest.

[0164] Experimental Example 12

[0165] Desorption recovery experiment: Take 1g of Suaeda salsa adsorbent prepared under the optimized conditions of Experimental Example 2 and place it on PM 10 Concentration 500 μg / m 3 The adsorption test was carried out in a closed box, and the removal rate was calculated. 0.1 mol / L hydrochloric acid was added to the adsorbed Suaeda salsa adsorbent, and the desorption process was 3 hours. After filtering with filter paper, it was washed with distilled water until neutral, and dried at 70℃. The above test process was repeated and tested 7 times to explore the changes in adsorption performance. The experimental results are as follows Fig.21 As shown in the figure, after multiple cycles, the removal rate decreased (F = 51.181, P < 0.01). 10 The initial concentration was 500 μg / m 3 After 6 times of adsorption, the removal rate reached 11.24%. Therefore, it was concluded that the Suaeda salsa adsorbent can be recycled at least 6 times, and it still has a high removal rate.

[0166] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for preparing a Suaeda salsa adsorbent, characterized in that: The following steps are involved: S1: mixing a cellulase solution and an acidic protease solution, and adding a citric acid solution thereto to adjust the pH to 4.0 to obtain a mixed enzyme solution; S2: Soak the cleaned Suaeda salsa in the mixed enzyme solution and then place in a water bath at 45-55°C for 30 minutes; S3: Raise the water bath temperature to 75°C and continue water bathing for 10 min to obtain a crude product; S4: The crude product is washed to neutrality, dried and crushed to obtain the Suaeda salsa adsorbent.

2. The method for preparing the Suaeda salsa adsorbent according to claim 1, characterized in that: The concentration of the mixed enzyme solution is 0.1-0.5 g / L, and the mass ratio of cellulase to acid protease in the mixed enzyme solution is 1-5:1-5.

3. The method for preparing the Suaeda salsa adsorbent according to claim 1, characterized in that: The concentration of the mixed enzyme solution is 0.3 g / L, and the mass ratio of cellulase to acid protease in the mixed enzyme solution is 1:

3.

4. The method for preparing the Suaeda salsa adsorbent according to claim 1, characterized in that: The concentration of the citric acid solution is 0.1 mol / L.

5. The method for preparing the Suaeda salsa adsorbent according to claim 1, characterized in that: The drying is performed in a forced air drying oven at 80-90° C. to a constant weight.

6. The Suaeda salsa grass adsorbent obtained by the method for preparing the Suaeda salsa grass adsorbent according to any one of claims 1 to 5.

7. The Suaeda salsa adsorbent according to claim 6 is effective in adsorbing PM 10 Application in.

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