A forsythia PM 2.5 Adsorbent and use thereof in adsorbing PM 2.5 ​

Abstract

This invention relates to the field of air pollution control technology, and in particular to a Forsythia suspensa PM2.5 solution. 2.5 Adsorbents and their role in adsorbing PM 2.5 Applications in [the field]. This invention uses Forsythia suspensa dead branches as raw material to modify them, and the optimal preparation method is ethyl acetate plus ferric chloride. The improved method of ethyl acetate plus ferric chloride is further optimized, namely, ferric chloride concentration of 0.02 mol / L, ethyl acetate concentration of 0.12 mol / L, ethyl acetate soaking time of 18.9 h, adsorption rate reaching 12.88%, and meeting the national secondary standard of 75 μg / mL after 24 h. 3 It decreased to 68 μg / m 3 Forsythia PM prepared 2.5 Adsorbent for PM 2.5 The adsorption effect at the 1% level is significantly superior to activated carbon (granules), diatomaceous earth (powder), bamboo charcoal, and AB-8 macroporous adsorption resin. After 8 desorption cycles and regeneration, it effectively removes PM2.5. 2.5 It still has some adsorption effect.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, and in particular to a Forsythia suspensa PM2.5 solution. 2.5 Adsorbents and their role in adsorbing PM 2.5 Applications in [the field]. Background Technology

[0002] PM 2.5 PM is a mixture of gases in the air, often formed from smog and emissions from industrial production. 2.5 PM is a type of tiny particulate matter, ≤2.5 μm in diameter, which can typically coexist with other gases in the air for extended periods and is easily inhaled. 2.5 It is highly toxic and can cause serious harm to the body if inhaled. Prolonged inhalation can cause headaches, dizziness, nausea, and severely affect the respiratory system.

[0003] Currently, products on the market that absorb PM2.5 are available. 2.5 Examples of suitable adsorbents include activated carbon and bamboo charcoal. Activated carbon has a large surface area, allowing for rapid adsorption, but it is expensive and easily affected by environmental factors, potentially causing secondary pollution. Bamboo charcoal offers better value for money, but it is prone to adsorption saturation. The adsorbents mentioned above have questionable adsorption effectiveness and do not achieve ideal results; therefore, they are not suitable for long-term PM removal. 2.5 The ideal approach.

[0004] Forsythia is abundant throughout the country. High-value utilization of forsythia waste helps protect the ecological environment, realizes the transformation from "waste" to "resource", conforms to the concept of circular economy, improves resource utilization efficiency, and promotes sustainable resource development. Summary of the Invention

[0005] To address the above problems, this invention provides a Forsythia PM... 2.5 Adsorbents and their role in adsorbing PM 2.5 Applications in [the field]. The Forsythia PM provided by this invention [is used in] [the field]. 2.5 The adsorbent is prepared using Forsythia suspensa dead branches as raw material, which not only improves the utilization efficiency of Forsythia suspensa resources, but also produces Forsythia suspensa PM2.5. 2.5 Adsorbent for PM 2.5 It has a good adsorption effect.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a Forsythia PM 2.5 Adsorbent, for preparing the Forsythia PM 2.5 The method for using adsorbents includes the following steps: The waste forsythia was decocted and then soaked in an ethyl acetate solution for 18.9 h; the concentration of the ethyl acetate solution was 0.12 mol / L. The soaked forsythia waste was soaked in ferric chloride solution for 30 minutes to obtain modified forsythia waste; the concentration of the ferric chloride solution was 0.02 mol / L. The modified Forsythia waste was dried and then pulverized to obtain Forsythia PM. 2.5 Adsorbent.

[0007] Preferably, the material passed through a 60-mesh sieve and the material passing through the sieve is the Forsythia PM. 2.5 Adsorbent.

[0008] Preferably, the soaked forsythia waste is rinsed until neutral before soaking in ferric chloride solution.

[0009] Preferably, the forsythia waste includes dead forsythia branches.

[0010] Preferably, the drying temperature is 80°C.

[0011] This invention provides the Forsythia PM described in the above technical solution. 2.5 Adsorbents adsorb PM 2.5 Applications in [the field].

[0012] Preferably, the Forsythia PM 2.5 Adsorbents adsorb PM 2.5 The ambient temperature was 22℃ and the humidity was 50%RH.

[0013] Preferably, the Forsythia PM 2.5 Adsorbents adsorb PM 2.5 The adsorption time was 50 min.

[0014] Preferably, the Forsythia PM 2.5 Adsorbents adsorb PM 2.5 PM 2.5 Concentration ≤500 μg / m 3 .

[0015] Preferred, Forsythia PM 2.5 The ratio of adsorbent to adsorption space is 4 g: 1 m 3 .

[0016] Beneficial effects: This invention modifies Forsythia suspensa branches using twigs as raw material, determining the optimal preparation method as ethyl acetate plus ferric chloride. The improved method of ethyl acetate plus ferric chloride is further optimized, specifically using a ferric chloride concentration of 0.02 mol / L, an ethyl acetate concentration of 0.12 mol / L, and an ethyl acetate soaking time of 18.9 h. The resulting Forsythia suspensa PM...2.5 Adsorbent for PM 2.5 It exhibits good adsorption performance, reaching 12.88%. The prepared Forsythia PM... 2.5 The adsorbent was tested at a particle size of 60 mesh, an addition amount of 4 g, a temperature of 22 ℃, a humidity of 50% RH, and an initial concentration of 500 μg / m³. 3 When the adsorption time is 50 min, for PM 2.5 The adsorption effect was the best; the adsorption process conformed more closely to the pseudo-second-order kinetics and the Freundlich isotherm, and was a physicochemical mixed adsorption with chemical adsorption as the main component. It was a multi-molecular layer heterogeneous site adsorption and a spontaneous endothermic reaction. After 24 hours of adsorption, it met the national secondary standard, and the concentration dropped to 68 μg / m³. 3 Forsythia PM prepared 2.5 Adsorbent for PM 2.5 The adsorption effect at the 1% level is significantly superior to activated carbon (granules), diatomaceous earth (powder), bamboo charcoal, and AB-8 macroporous adsorption resin. After 8 desorption cycles and regeneration, it effectively removes PM2.5. 2.5 It still has some adsorption effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0018] Figure 1 The effect of ferric chloride concentration on PM removal by modified Forsythia 2.5 The impact results; Figure 2 The effect of slag particle size on the adsorption of PM by Forsythia suspensa 2.5 The impact results; Figure 3 The amount added affects the adsorption of PM by Forsythia suspensa. 2.5 The impact results; Figure 4 To study the effects of different temperatures on the adsorption of PM by Forsythia suspensa residue 2.5 The impact results; Figure 5 To study the effect of different humidity levels on the adsorption of PM by Forsythia suspensa residue 2.5 The impact results; Figure 6 For different PM 2.5 Initial concentration at different temperatures for the adsorption of PM by Forsythia 2.5 The impact results; where 300, 400, 500, 600 and 700 in the legend represent different PM levels. 2.5 Initial concentration, all in μg / m³ 3 ; Figure 7The results show the effect of different adsorption times on the adsorption effect of Forsythia suspensa at different temperatures; in the figure, 20, 30, 40, 50 and 60 represent the adsorption time, and the unit is min. Figure 8 The results of scanning electron microscopy analysis of different Forsythia species are shown; from left to right, they are the original Forsythia, the optimized Forsythia, and the Forsythia after adsorption. Figure 9 The results show the infrared spectra of Forsythia suspensa in different morphologies; among them, the pink line (a) represents the untreated original Forsythia suspensa, the red line (b) represents the optimized Forsythia suspensa, and the blue line (c) represents the Forsythia suspensa after adsorption. Figure 10 For PM 2.5 Adsorption isotherms; Figure 11 Linear Langmuir adsorption isotherms; Figure 12 The Freundlich adsorption isotherm is linear; Figure 13 For PM 2.5 Adsorption kinetics curves; Figure 14 The curve is a quasi-first-order rate equation. Figure 15 The curve is a quasi-second-order rate equation. Figure 16 The results show the relationship between temperature and adsorption amount; Figure 17 Forsythia absorbs PM 2.5 Thermodynamic curves; Figure 18 To different adsorption materials for PM 2.5 The results of the adsorption effect comparison; Figure 19 The results of desorption and regeneration of modified Forsythia suspensa; In the figure, different letters represent significant differences between different groups. Detailed Implementation

[0019] This invention provides a Forsythia PM 2.5 Adsorbent, for preparing the Forsythia PM 2.5 The method for using adsorbents includes the following steps: The waste forsythia was decocted and then soaked in an ethyl acetate solution for 18.9 h; the concentration of the ethyl acetate solution was 0.12 mol / L. The soaked forsythia waste was soaked in ferric chloride solution for 30 minutes to obtain modified forsythia waste; the concentration of the ferric chloride solution was 0.02 mol / L. The modified Forsythia waste was dried and then pulverized to obtain Forsythia PM. 2.5 Adsorbent.

[0020] In one embodiment, the material is pulverized through a 60-mesh sieve, and the material passing through the sieve is the Forsythia PM. 2.5 Adsorbent.

[0021] As one implementation method, the soaked forsythia waste is rinsed until neutral before soaking in ferric chloride solution.

[0022] In one embodiment, the forsythia waste includes withered forsythia branches.

[0023] In one embodiment, the drying temperature is 80°C.

[0024] Previous research in this invention has revealed the effects of different modification methods on PM. 2.5 The adsorption effects of different compounds varied, with ethyl acetate plus ferric chloride > alkaline scalding > calcium chloride coenzyme > esterified coenzyme. Considering social, economic, and environmental benefits, a method of soaking Forsythia suspensa in 0.12 mol / L ethyl acetate and 0.02 mol / L ferric chloride for 18.9 h was used to modify Forsythia suspensa into a biosorbent. The prepared Forsythia suspensa PM2.5... 2.5 The adsorbent was tested at a particle size of 60 mesh, an addition amount of 4 g, a temperature of 22 ℃, a humidity of 50% RH, and an initial concentration of 500 μg / m³. 3 When the adsorption time is 50 min, for PM 2.5 The adsorption effect is the best; the adsorption process conforms more to the pseudo-second-order kinetics and Freundlich isotherm, and is a physicochemical mixed adsorption with chemical as the main component. It is a multi-molecular layer heterogeneous site adsorption and a spontaneous endothermic reaction. After 24 hours, it reaches the national secondary standard of 75 μg / m³. 3 It decreased to 68 μg / m 3 Forsythia PM prepared 2.5 Adsorbent for PM 2.5 The adsorption effect at the 1% level is significantly superior to activated carbon (granules), diatomaceous earth (powder), bamboo charcoal, and AB-8 macroporous adsorption resin. After 8 desorption cycles and regeneration, it effectively removes PM2.5. 2.5 It still has some adsorption effect.

[0025] Based on the above advantages, the present invention provides the Forsythia PM described in the above technical solution. 2.5 Adsorbents adsorb PM 2.5 Applications in [the field].

[0026] As one implementation method, the Forsythia PM 2.5 Adsorbents adsorb PM 2.5 The ambient temperature was 22℃ and the humidity was 50%RH.

[0027] As one implementation method, the Forsythia PM 2.5Adsorbents adsorb PM 2.5 The adsorption time was 50 min.

[0028] As one implementation method, the Forsythia PM 2.5 Adsorbents adsorb PM 2.5 PM 2.5 Concentration ≤500 μg / m 3 .

[0029] As one implementation method, Forsythia PM 2.5 The ratio of adsorbent to adsorption space is 4 g: 1 m 3 .

[0030] To further illustrate the present invention, the following description, in conjunction with embodiments and accompanying drawings, describes a Forsythia suspensa PM (PM) product provided by the present invention. 2.5 Adsorbents and their role in adsorbing PM 2.5 The applications described in detail are not intended to limit the scope of protection of this invention.

[0031] Preparation Example The reagents used in the following examples were obtained from the following sources: Forsythia suspensa twigs were obtained from Shanxi Huatuo Agricultural Technology Co., Ltd., PM 2.5 The substances produced by burning fishing mosquito coils, activated carbon, diatomaceous earth and bamboo charcoal were all purchased from Tianjin Ruijinte Chemical Co., Ltd., and macroporous adsorption resin AB-8 was purchased from Shandong Keyuan Biochemical Co., Ltd.

[0032] Leakage rate determination of sealed chamber: ; Modified Forsythia suspensa for PM 2.5 Removal rate calculation formula: Removal rate = ; Modified Forsythia suspensa for PM 2.5 Formula for calculating adsorption capacity: ; Where: P is the empty box leakage rate; C0 is the PM in the sealed box. 2.5 initial concentration (μg / m 3 C represents the equilibrium concentration (μg / m³) of the Forsythia suspensa residue after adsorption in the sealed chamber. 3 V is the volume of the sealed box (m³). 3 ); q is the adsorption amount (μg / g); M is the amount of Forsythia suspensa residue added (g).

[0033] Example 1 Preparation of Forsythia suspensa adsorbent Cleaning: Rinse 30g of forsythia clean; Cooking: Put the forsythia in a pot and cook for 30 minutes; Prepare solutions and soak: Prepare five 500 mL solutions of 0.1 mol / L ethyl acetate and soak for one day; prepare 500 mL solutions of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L and 0.5 mol / L ferric chloride respectively. Divide the ethyl acetate-treated Forsythia into five equal portions and soak them in the prepared ferric chloride solutions for 30 min. Adjusting pH: Rinse the treated forsythia repeatedly and test the pH with a pH meter until it is neutral; Drying and pulverizing: Forsythia is placed in an 80 ℃ oven and dried to constant weight. The dried forsythia is then pulverized and passed through a 60 mesh sieve. Sealing: Place in a sealed bag and store in a cool, ventilated, and dry place.

[0034] The effect of ferric chloride concentration on PM 2.5 The results of the impact are shown in Figure 1 The results showed that the adsorption value increased with increasing ferric chloride concentration; at a ferric chloride concentration of 0.4 mol / L, the modified Forsythia suspensa adsorbed more effectively on PM2.5. 2.5 The adsorption performance was the highest, with a removal rate of 11.8%. The adsorption value gradually decreased after reaching a concentration of 0.4 mol / L, and the adsorption performance was poor at 0.1 mol / L, with a removal rate of 5.08%. The yield of this experimental method was 89%.

[0035] Example 2 I. Experimental Procedure 1. The optimal modification method for the dead branches of Forsythia suspensa, as determined by Example 1, is ferric chloride plus ethyl acetate. A two-stage regression experiment was conducted on the modified branches, and a three-factor, five-level coding table was developed, as shown in Table 1.

[0036] Table 1. Three-Factor Five-Level Coding Table

[0037] Based on the three-factor, five-level coding table, 23 Forsythia suspensa adsorbents, 2 g each, were prepared and placed in a sealed chamber under PM2.5. 2.5 The concentration was kept constant at 500 μg / m 3 At that time, the adsorbent was placed in a closed box under indoor temperature conditions for adsorption. After a certain period of time, it was taken out, the values ​​on the instrument were recorded, and the removal rate was calculated.

[0038] 2. Environmental Factors Experiment Experimental study on the effects of Forsythia suspensa residue on PM2.5 using six environmental factors 2.5 Adsorption effect: Investigating the particle size, dosage, and PM2.5 of Forsythia suspensa residue. 2.5 The effects of initial concentration, temperature, adsorption time, and humidity on adsorption efficiency were investigated. Different levels were set, and PM2.5 levels were calculated under each condition using a closed-chamber experiment. 2.5 Removal rate.

[0039] 3. Adsorption mechanism study a. Scanning electron microscopy (SEM) observation Scanning electron microscopy (SEM) works by detecting changes in the microscopic porosity of a material surface. This study uses the instrument to scan the adsorption sites of raw Forsythia suspensa, modified Forsythia suspensa, and the modified Forsythia suspensa after adsorption, analyzing the conditions before and after adsorption of these three substances.

[0040] b. FTIR (Full-Time Infrared) Analysis The core principle of Fourier Transform Infrared Spectroscopy (FTIR) is to detect adsorbed materials using light emitted from an infrared light source. FTIR offers high resolution, simple operation, and fast measurement speed, enabling the study of Forsythia suspensa in its original state and before and after adsorption, and determining the presence of polymeric chemical functional groups.

[0041] c. Elemental analyzer The reaction principle of elemental analysis is based on the high-temperature combustion-desorption separation thermal island detection method. It allows for the detection of internal elemental content in materials over a wide detection area. Elemental analysis of C, H, S, and N elements is performed on various adsorbent materials. Elemental analyzers are widely used in scientific research.

[0042] d. Parameter analysis of the physical adsorption analyzer (BET) It mainly measures parameters such as pore size, surface area, particle size, and pore distribution on a sample using the principle of laser scattering.

[0043] e. Adsorption isotherm Forsythia absorbs PM 2.5 It is a dynamic equilibrium process. The key is that at a certain temperature, the removal rate and the adsorption rate are constantly changing over time.

[0044] The expression for Langmuir is: ; The expression for Freundlich is: ; Taking the logarithm of both sides of the above equation transforms it into a linear form: ; Where: C is the equilibrium concentration (μg / m³) 3 ); q is the equilibrium adsorption capacity (μg / g); q m It is the saturated adsorption capacity (μg / g); b is the adsorption equilibrium constant; K and n represent constants at a given temperature.

[0045] f. Adsorption kinetics In PM 2.5 Adsorption experiments were conducted under conditions of the same initial concentration but different adsorption times. The relationship between the adsorption rate q of Forsythia suspensa adsorbent and time t was analyzed, and the data were fitted using kinetic formulas. Generally, pseudo-first-order and pseudo-second-order kinetic equations were used for fitting.

[0046] The pseudo-first-order dynamic equation of Lagergren is: ; The pseudo-second-order dynamic equation for H0 is: ; Where: Q is the equilibrium adsorption amount (μg·g) -1 ); q is the amount of adsorption at time t (μg·g) -1 ); k1 is the first-order adsorption rate constant (min) -1 ); k2 is the second-order adsorption rate constant (g·μg). -1 ·min -1 ).

[0047] g. Adsorption thermodynamics The adsorption process was experimentally investigated under the same initial concentration but different temperatures. After adsorption, the data were analyzed and processed, and the adsorption thermodynamic parameters, such as the adsorption enthalpy ΔH, the adsorption Gibbs free energy ΔG at different temperatures, and the adsorption entropy ΔS, were calculated. The specific calculations used the following formulas: The formula for calculating the heat of adsorption (ΔH) is: ; ; Where: ΔG0 is the standard Gibbs free energy, in kJ / mol; R is the thermodynamic gas constant, with a value of 8.314 J / (mol·K); T is the thermodynamic temperature, and its unit is K. ΔH0 is the enthalpy change of the reaction, with units of kJ / mol; ΔS0 is the entropy variable, with units of J / (mol·K); Kc is the thermodynamic equilibrium constant.

[0048] 4. Different materials affect PM 2.5 Adsorption performance investigation The optimal method was determined using software, and large quantities of Forsythia suspensa adsorbent materials were prepared. The modified and original Forsythia suspensa adsorbents were compared with four commercially available adsorbents (activated carbon, bamboo charcoal, diatomaceous earth, and AB-8 macroporous adsorption resin). Six petri dishes were prepared, with 4 g of each adsorbent weighed and placed in each dish. The instrument was then placed in a sealed chamber, and mosquito coils were lit. After standing for 8-10 seconds, the mosquito coils were removed, and the values ​​were allowed to stabilize at 500±10 μg / m³. 3 At each time point, the Forsythia suspensa adsorbent was placed in the chamber for adsorption (30 min, 60 min, 90 min, 120 min, 150 min), and the values ​​were recorded and the removal rate was calculated. The specific specifications of the adsorbent are shown in Table 2.

[0049] Table 2 Adsorbent Specifications

[0050] 5. Desorption and regeneration After adsorption, the forsythia residue was spread evenly in a petri dish and exposed to the sun for 2 hours before adsorption of PM2.5 again. 2.5 The above experiment was repeated 8 times, and the removal rate was calculated to further explore its adsorption performance.

[0051] II. Results and Analysis The quadratic regression orthogonal rotational combination design is shown in Table 3 below.

[0052] Table 3. Three-factor quadratic regression orthogonal rotational combination design.

[0053] Table 4. Analysis of First-Order Variance Table

[0054] As shown in the first-order ANOVA table (Table 4), X1X2 is significant at the 1% level.

[0055] Based on the software analysis of experimental data, the mathematical regression equations for the initial concentration of ferric chloride (X1), the initial concentration of ethyl acetate (X2), the immersion time of ethyl acetate (X3), and the removal rate (Y) were obtained: Y=7.46807+0.06900X1+0.10547X2+0.30920X3+1.17426X1 2 +0.76767X2 2 -0.00485X3 2 +0.46125X1X2-0.29875X1X3-0.07375X2X3.

[0056] At the level of α=0.01, F in the model 失拟=MS 失拟 / MS 误差 =2.649 <F 0.01(5,8) =6.63, the experiment proves that the error is extremely small, and all unknown factors have been taken into account in the experimental design; F 回归 =MS 回归 / MS 剩余 =5.970>F 0.01(9,13) =4.19, indicating that the regression equation is significant, the experimental inference is highly reliable, the prediction is accurate, and the model is valid.

[0057] Based on the significance test, the non-significant terms at the α=0.10 level were identified. Further analysis of variance was performed on the remaining factors, as shown in Table 5. This resulted in a simplified regression equation (α=0.10): Y = 7.46807 + 1.17426X1 2 +0.76767X2 2 .

[0058] Table 5. Analysis of Quadratic Variance

[0059] Among X1X2, X1X3, and X2X3, the effect of X1X2 is more significant. The effects of ferric chloride concentration (X1) and ethyl acetate concentration (X2) on the removal rate (Y) (other factors are at zero level) are shown in Table 6.

[0060] Table 6. Effects of ferric chloride concentration (X1) and ethyl acetate concentration (X2) on removal rate

[0061] The results showed that, with equal soaking times, as the ferric chloride concentration gradually increased, the removal rate of the Forsythia suspensa adsorbent first decreased and then increased with increasing ethyl acetate concentration; similarly, as the ethyl acetate concentration gradually increased, the removal rate of the Forsythia suspensa adsorbent first decreased and then increased with increasing ferric chloride concentration. At the highest point (-1.682, 1.682), with a ferric chloride concentration of 0.12 mol / L and an ethyl acetate concentration of 0.02 mol / L, the maximum removal rate was 12.96%.

[0062] Analysis of the obtained experimental data showed that the three factors were at the level of (-1.682, -1.682, -1.682), namely, ferric chloride concentration of 0.12 mol / L, ethyl acetate concentration of 0.02 mol / L, and soaking time of 18.9 h. The predicted value of Y... max The result was 12.96%. Under room temperature conditions, the result was verified to be 12.88%, and the ratio of the actual value to the model's best value was 0.994, which is close to 1, further verifying the reliability of the model.

[0063] Depend on Figure 2It can be seen that the particle size of the Forsythia suspensa adsorbent initially increased and then decreased, with a highly significant difference at the 1% level (F=166.264, P=0.0001<0.01). This phenomenon is related to PM2.5. 2.5 The pollutants themselves have a diameter of 2.5 μm. Conversely, as the particle size of the slag increases, the effect on PM2.5 decreases. 2.5 The adsorption effect is not good. The adsorption effect is best with a particle size of 60 mesh, which is effective for PM2.5. 2.5 The removal rate reached 14.46%, with the worst effect at a particle size of 100 mesh, achieving a removal rate of 9.80%. Therefore, a particle size of 60 mesh was used in subsequent experiments.

[0064] Depend on Figure 3 It can be seen that Forsythia suspensa adsorbent has an effect on PM2.5. 2.5 The adsorption effect initially increased and then decreased with increasing dosage, dropping further at 5 g. This decrease was attributed to adsorbent accumulation in the petri dish at 5 g, leading to a lower adsorption removal rate. (The text then abruptly shifts to a discussion of the effects of different dosages of Forsythia suspensa adsorbent on PM2.5.) 2.5 The difference was highly significant at the 1% level (F=1083.215, P=0.0001<0.01). This phenomenon is related to PM. 2.5 The pollutant itself has a diameter of 2.5 μm; as the amount added increases, it becomes detrimental to PM2.5 levels. 2.5 The adsorption effect is best when 4 g is added, especially for PM2.5. 2.5 The removal rate reached 19.15%. The effect was worst when the amount added was 1 g, with a removal rate of 7.37%. Therefore, the slag particle size was 4 g in subsequent experiments.

[0065] Depend on Figure 4 It can be seen that, at different temperatures, the adsorption of PM by Forsythia suspensa adsorbent... 2.5 The adsorption effect showed a trend of first increasing and then decreasing, reaching a highly significant difference at the 1% level (F=277.324, P=0.0001<0.01). The removal rate was highest at 22 ℃, reaching 19.50%, and lowest at 14 ℃, reaching 13.00%. Due to the difficulty in controlling the temperature, subsequent experiments were conducted in a randomized laboratory at room temperature.

[0066] Depend on Figure 5 It can be seen that Forsythia suspensa adsorbent has an effect on PM2.5. 2.5 The adsorption effect of Forsythia suspensa adsorbent first increases and then decreases with increasing humidity. The adsorption effect of Forsythia suspensa adsorbent on PM2.5 varies with humidity levels. 2.5 The difference was highly significant at the 1% level (F=440.896, P=0.0001<0.01). The adsorption effect was best at 50% RH, particularly for PM2.5. 2.5 The removal rate reached 16.43%, with the worst effect at 40% RH, where the removal rate was 7.57%. Due to the difficulty in controlling humidity, subsequent experiments were conducted using laboratory humidity.

[0067] Depend on Figure 6 It can be seen that, under different initial concentrations and at three temperatures, the results show that the initial concentration first increases and then decreases with increasing concentration. The interaction between the initial concentration and temperature factors both reached a highly significant difference at the 1% level (F0). 浓度 =16.161, P=0.0007<0.01; F 温度 =26.239, P=0.0003<0.01; F 浓度×温度 =16.626, P=0.0001<0.01). Initial concentration 500 μg / m 3 At that time, the effect of Forsythia adsorbent on PM2.5 2.5 The best removal effect is achieved at 20℃, 22℃, and 24℃, with the best effect on PM2.5 removal. 2.5 The removal rates were 10.47%, 11.73%, and 13.83%, respectively; the initial concentration was 300 μg / m³. 3 The results were the worst, with removal rates of only 6.67%, 8.28%, and 10.69%.

[0068] Depend on Figure 7 It can be seen that, under different adsorption times and temperatures, the adsorption rate first increases and then decreases with increasing time, and the interaction between adsorption time and temperature reaches a highly significant difference at the 1% level (F0). 时间 =230.065, P=0.0001<0.01; F 温度 =96.303, P=0.0001<0.01; F 时间×温度 =4.416, P=0.0013<0.01). At an adsorption time of 50 min, the adsorbent from forsythia stalks effectively reduced PM2.5 concentration. 2.5 The best removal effect is achieved at 20℃, 22℃, and 24℃, with the best effect on PM2.5 removal. 2.5 The removal rates were 12.96%, 14.72%, and 15.29%, respectively. The effect was worst at an adsorption time of 20 min, with removal rates of only 7.06%, 8.48%, and 9.38%.

[0069] Depend on Figure 8 It can be seen from instrumental analysis that the original Forsythia has a dense texture and few pores, which is not conducive to the adsorption of PM. 2.5 Chemically treated forsythia stalks have a looser texture and more pronounced wrinkles, resulting in extremely strong adsorption properties. The surface of the treated forsythia stalks is relatively smooth with fewer pores and wrinkles. The looser surface of chemically treated forsythia stalks increases the surface adsorption area, which is beneficial for adsorbing PM2.5. 2.5 .

[0070] from Figure 9 It was found that the peak was 3403 cm. -1The presence of hydroxyl (-OH) functional groups on both sides indicates a distinct stretching vibration peak with a relatively broad peak shape; the peak value is 1742 cm⁻¹. -1 It forms a sharp peak at 1637 cm. -1 C=C stretching vibrations occurred nearby; 1049cm -1 The peak at this point mainly originates from the -CO- characteristic peak, which is caused by the CO stretching vibration in carboxylic acids.

[0071] Table 7 shows that modified Forsythia suspensa twigs, original Forsythia suspensa twigs, and adsorbed Forsythia suspensa twigs contain multiple elements including N, C, H, and S. Among them, C and H are the most abundant, with C content at 50.510% and H content at 6.376%, while the contents of N and S decrease.

[0072] Table 7. Elemental Analysis of Original, Optimized, and Adsorbed Forsythia Blossom Twigs

[0073] Detection using a BET machine yielded the specific surface area parameters of the original and modified Forsythia suspensa twig adsorbents. Table 8 clearly shows a significant change in the values ​​between the original and modified Forsythia suspensa twig adsorbents. Increased pore volume and pore size significantly impacted PM2.5 levels. 2.5 It has a strong adsorption effect, proving that the Forsythia adsorbent has a multi-site high-efficiency adsorption function.

[0074] Table 8 BET Results

[0075] The most commonly used models for adsorption equilibrium are the Langmuir and Freundlich isotherms.

[0076] Under temperature conditions of 20 ℃, 22 ℃, and 24 ℃, the adsorption capacity q (μg / g) was compared with the equilibrium concentration C (μg / m³). 3 Plot the adsorption isotherm curve, see Figure 10 .Will Figure 10 The data were fitted with the Langmuir and Freundlich adsorption isotherm equations, and the results are shown in [the table]. Figures 11-12 Forsythia suspensa residue adsorbs PM. 2.5 The adsorption isotherm parameters are shown in Table 9.

[0077] Table 9. PM adsorption by Forsythia suspensa residue. 2.5 Adsorption isotherm parameters

[0078] The results showed that the correlation coefficients for the Freundlich equation fitting were 0.9036, 0.9453, and 0.9293, respectively, indicating a good linear trend. The correlation coefficients for the Langmuir isotherm were 0.993, 0.9973, and 0.9918. This proves that the modified Forsythia conforms to the Freundlich isotherm equation, and the experimental results show multi-site, multi-layer adsorption. The Langmuir adsorption isotherm calculations yielded the effect of modified Forsythia on PM2.5. 2.5 The saturated adsorption capacities were 14.0252 μg / g, 17.5747 μg / g, and 13.6986 μg / g, respectively.

[0079] Depend on Figure 13 It can be seen that the increase in Forsythia suspensa residue over time has an impact on PM2.5. 2.5 The adsorption capacity showed an increasing trend. Experimental data showed that the adsorption effect was best at an adsorption time of 50 min. This indicates that Forsythia suspensa effectively adsorbs PM2.5. 2.5 It possesses strong adsorption capacity. After 24 hours of testing in the laboratory, it was proven that this material meets the national standard of 68 μg / m³. 3 .

[0080] The data were fitted using pseudo-first-order and pseudo-second-order dynamic equations, and the results are shown in [the table]. Figures 14-15 The results showed that two types of images were fitted, with the pseudo-second-order coefficient R0... 2 The values ​​are 0.9866, 0.9654, and 0.9903, respectively, which are the quasi-first-order coefficients R. 2 The values ​​were higher than 0.9796, 0.9492, and 0.9694 (Table 10), demonstrating that the modified Forsythia suspensa adsorbed PM2.5. 2.5 It follows pseudo-second-order kinetics, and the process is chemisorption.

[0081] Table 10 Parameters of the Dynamic Equation

[0082] The relationship between temperature and adsorption capacity is as follows: Figure 16 As shown, Forsythia adsorbs PM2.5 2.5 Thermodynamic curves are shown Figure 17 .

[0083] Table 11 Modified Forsythia suspensa adsorbs PM 2.5 Thermodynamic parameters

[0084] The results show that ΔH0 > 0, proving that this adsorbent adsorbs PM. 2.5 The process is an endothermic reaction, ΔG0 < 0, proving that this type of adsorbent adsorbs PM. 2.5 The process is spontaneous; from Figure 17 It was found that the fitting coefficient of the thermodynamic curve of the Forsythia suspensa adsorbent was R.2 =0.9526, which proves that the adsorption process fits the thermodynamic laws well.

[0085] Depend on Figure 18 It can be seen that, under the same temperature of 26 ℃ and humidity of 43%RH, the modified forsythia branches and other materials have different effects on PM2.5. 2.5 The comparison of removal effects showed that the F-test revealed highly significant differences at the 1% level for different adsorbent materials, different adsorption times, and the interaction between materials and time (F0). 材料 =87.793, P=0.0001<0.01; F 时间 =17.422, P=0.0001<0.01; F 材料x时间 =60.960, P=0.0001<0.01), further analysis of the differences among different adsorbent materials shows that modified Forsythia suspensa branches have a positive effect on PM2.5. 2.5 At the 1% level, the removal rate was significantly better than other adsorbents, namely modified Forsythia suspensa branches > activated carbon (granules) > diatomaceous earth (powder) > bamboo charcoal > AB-8 macroporous adsorption resin > original Forsythia suspensa branches, with activated carbon being the second best, bamboo charcoal and AB-8 macroporous adsorption resin being the worst, and original Forsythia suspensa branches showing the best removal rate for PM2.5. 2.5 The removal effect is the worst.

[0086] Table 12 Analysis of Variance Table (Duncan's Method)

[0087] Table 13 Effects of different materials on PM 2.5 The effect of adsorption (Duncan method)

[0088] according to Figure 19 It can be seen that after eight desorption and regeneration experiments, Forsythia suspensa effectively controlled PM2.5. 2.5 It still has some adsorption capacity; however, with increasing adsorption cycles, Forsythia's ability to adsorb PM2.5 decreases. 2.5 The adsorption capacity gradually decreases, and after the 8th desorption, the adsorption capacity for PM2.5 decreases. 2.5 The removal rate was 8.36% (F=400.245, p=0.0001<0.01), indicating that the Forsythia adsorbent still has a certain regeneration capacity after multiple cycles, and the overall adsorption effect is good.

[0089] In summary, this invention modifies Forsythia suspensa branches using four treatments, identifying the optimal preparation method as ethyl acetate plus ferric chloride. Further optimization was achieved using a quadratic orthogonal rotational regression combination, with the optimal concentrations being ferric chloride 0.02 mol / L, ethyl acetate 0.12 mol / L, and ethyl acetate soaking time of 18.9 h. The predicted Yg... max=12.96%, measured 12.88%, actual value / model optimum value = 0.994. The adsorbent from withered forsythia stalks was effective at the following conditions: particle size 60 mesh, dosage 4 g, temperature 22 ℃, humidity 50%RH, initial concentration 500 μg / m³. 3 At an adsorption time of 50 min, the Forsythia adsorbent effectively adsorbs PM2.5. 2.5 The adsorption effect is the best; the adsorption process conforms more to the pseudo-second-order kinetics and Freundlich isotherm, and is a physicochemical mixed adsorption with chemical as the main component. It is a multi-molecular layer heterogeneous site adsorption and a spontaneous endothermic reaction. After 24 hours, it reaches the national secondary standard of 75 μg / m³. 3 It decreased to 68 μg / m 3 Modified forsythia stalks on PM2.5 2.5 The adsorption effect at the 1% level is significantly superior to activated carbon (granules), diatomaceous earth (powder), bamboo charcoal, and AB-8 macroporous adsorption resin. The forsythia stalk adsorbent, after 8 desorption cycles and regeneration, effectively removes PM2.5. 2.5 It still has some adsorption effect.

[0090] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A type of Forsythia PM 2.5 Adsorbent, characterized in that, Preparation of the Forsythia PM 2.5 The method for using adsorbents includes the following steps: The waste forsythia was decocted and then soaked in an ethyl acetate solution for 18.9 h; the concentration of the ethyl acetate solution was 0.12 mol / L. The soaked forsythia waste was soaked in ferric chloride solution for 30 minutes to obtain modified forsythia waste; the concentration of the ferric chloride solution was 0.02 mol / L. The modified Forsythia waste was dried and then pulverized to obtain Forsythia PM. 2.5 Adsorbent.

2. The Forsythia PM according to claim 1 2.5 Adsorbent, characterized in that, The powder is pulverized through a 60-mesh sieve, and the material passing through the sieve is the Forsythia PM. 2.5 Adsorbent.

3. The Forsythia PM according to claim 1 2.5 Adsorbent, characterized in that, The soaked forsythia waste was rinsed until neutral before soaking in ferric chloride solution.

4. The Forsythia PM according to claim 1 or 3 2.5 Adsorbent, characterized in that, The forsythia waste includes dead forsythia branches.

5. The Forsythia PM according to claim 1 2.5 Adsorbent, characterized in that, The drying temperature is 80°C.

6. The Forsythia PM according to any one of claims 1 to 5 2.5 Adsorbents adsorb PM 2.5 Applications in [the field].

7. The application according to claim 6, characterized in that, The Forsythia PM 2.5 Adsorbents adsorb PM 2.5 The ambient temperature was 22℃ and the humidity was 50%RH.

8. The application according to claim 6, characterized in that, The Forsythia PM 2.5 Adsorbents adsorb PM 2.5 The adsorption time was 50 min.

9. The application according to claim 6, characterized in that, The Forsythia PM 2.5 Adsorbents adsorb PM 2.5 PM 2.5 Concentration ≤500 μg / m 3 .

10. The application according to claim 6, characterized in that, Forsythia PM 2.5 The ratio of adsorbent to adsorption space is 4g:1m 3 .

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