A forsythia adsorbent and its application in adsorbing total volatile organic compounds

Abstract

The present application relates to the air pollution control technical field, particularly to a forsythia suspensa adsorbent and its application in adsorbing total volatile organic compounds (TVOC). The present application finds that the adsorption effect of the prepared forsythia suspensa adsorbent on TVOC is the best after calcium chloride + lignin peroxidase is used to treat forsythia suspensa dry branches, and the specific preparation conditions are used to further improve the adsorption effect of the forsythia suspensa adsorbent on TVOC. Moreover, the prepared forsythia suspensa adsorbent can be reused, and still has a certain adsorption effect on TVOC after 8 times of desorption and regeneration. The present application not only provides a good adsorption material for treating TVOC in the air, but also realizes the waste utilization of forsythia suspensa dry branches.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, and in particular to a forsythia adsorbent and its application in the adsorption of total volatile organic compounds. Background Technology

[0002] TVOC is the abbreviation for Total Volatile Organic Compounds. As a complex pollutant in indoor air, it is one of the most serious pollutants affecting indoor air quality. TVOC consists of colorless aromatic benzene compounds. Generally, TVOC has a boiling point lower than water, around 80°C. Therefore, under normal temperatures, especially in summer, TVOC is highly volatile. TVOC has a strong odor, and prolonged exposure to environments containing TVOC odors can not only affect physical health but also have adverse psychological effects.

[0003] Currently, China is also focusing on developing environmentally friendly materials that can degrade and adsorb TVOCs. For example, research is underway to develop indoor coatings containing components that can adsorb and decompose TVOCs, such as adding coconut shell activated carbon, nano-titanium dioxide, and graphene oxide to the coatings, utilizing their adsorption and photocatalytic properties to degrade TVOCs. In addition, there are purification technologies utilizing natural plant extracts, such as extracting essences from common Chinese medicinal herbs like mugwort, alfalfa, and forsythia, and using specific processes to decompose harmful substances like TVOCs in the air. However, there is currently a lack of reports on forsythia adsorbing TVOCs. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a Forsythia suspensa adsorbent and its application in the adsorption of total volatile organic compounds (TVOCs). The Forsythia suspensa adsorbent prepared by this invention exhibits excellent adsorption performance for TVOCs and is reusable, making it suitable for adsorbing TVOCs from the air.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a Forsythia suspensa adsorbent, and the method for preparing the Forsythia suspensa adsorbent includes the following steps: The waste forsythia was boiled and then soaked in a calcium chloride solution with a concentration of 0.02 mol / L. After rinsing the soaked Forsythia waste to neutral, it was then soaked in a lignin peroxidase solution and heated in a 65 ℃ water bath for 36.5 min to inactivate the enzyme, thus obtaining enzymatically hydrolyzed Forsythia waste; the concentration of the lignin peroxidase was 0.32 mg / mL; and the enzyme activity of the lignin peroxidase was 1167 U / L. The enzymatically hydrolyzed Forsythia waste is dried and then pulverized to obtain the Forsythia adsorbent.

[0006] Preferably, the particle size of the Forsythia suspensa adsorbent is ≤40 mesh.

[0007] Preferably, the time for soaking the decocted forsythia waste in calcium chloride solution is 45 minutes.

[0008] Preferably, the forsythia waste is forsythia dead branches.

[0009] Preferably, the enzyme inactivation treatment method includes: inactivating the enzyme by heating in a water bath at 75~100℃.

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

[0011] This invention provides the application of the Forsythia suspensa adsorbent described in the above technical solution in the adsorption of total volatile organic compounds.

[0012] Preferably, the ambient temperature for the Forsythia adsorbent to adsorb total volatile organic compounds is 24°C and the humidity is 45%RH.

[0013] Preferably, the adsorption time of the Forsythia suspensa adsorbent when adsorbing total volatile organic compounds is ≥150 min.

[0014] Preferably, the concentration of total volatile organic compounds (TVOCs) in the Forsythia suspensa adsorbent is ≤1.6 mg / m³. 3 The ratio of Forsythia suspensa adsorbent to the adsorption space is 2 g: 1 m 3 .

[0015] Beneficial effects: This invention utilizes calcium chloride and lignin peroxidase to treat dead forsythia branches, resulting in a forsythia adsorbent with the best adsorption effect on TVOCs. Specific preparation conditions further enhance the TVOC adsorption efficiency of the forsythia adsorbent. Furthermore, the forsythia adsorbent prepared by this invention is reusable, retaining a certain adsorption effect on TVOCs even after eight desorption and regeneration cycles. This invention not only provides an excellent adsorbent material for controlling TVOCs in the air but also realizes the utilization of dead forsythia branches. Attached Figure Description

[0016] 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.

[0017] Figure 1 The results show the effect of lignin peroxidase concentration on adsorption efficiency; Figure 2 The results show the effect of Forsythia suspensa residue particle size on TVOC removal rate; Figure 3 TVOC removal rate corresponding to different amounts of Forsythia suspensa added; Figure 4 TVOC removal rates at different adsorption temperatures; Figure 5 TVOC removal rates corresponding to different adsorption humidity levels; Figure 6 TVOC removal rate corresponding to different adsorption times; Figure 7 The results show the effect of initial concentration on the removal of TVOC by Forsythia suspensa. Figure 8 Forsythia suspensa infrared spectrum; Figure 9 Analysis results of different Forsythia suspensa electron microscope lenses; Figure 10 The results show the comparison of the adsorption effects of different adsorbent materials on TVOC. Figure 11 This represents the desorption and recycling results of the Forsythia suspensa adsorbent; Figure 12 The effect of adsorption time on the adsorption capacity of Forsythia suspensa residue; Figure 13 The fitting results are for the quasi-first-order dynamic equations; Figure 14 The fitting results are for the quasi-second-order dynamic equations; Figure 15 The relationship between initial VOC concentration and adsorption amount; Figure 16 This refers to the Langmuir isotherm. Figure 17 This refers to the Freundlich isotherm. Figure 18 The results show the effect of adsorption temperature on TVOC adsorption efficiency. Figure 19 This is the fitting result of the adsorption thermodynamic equation. Detailed Implementation

[0018] This invention provides a Forsythia suspensa adsorbent, and the method for preparing the Forsythia suspensa adsorbent includes the following steps: The waste forsythia was boiled and then soaked in a calcium chloride solution with a concentration of 0.02 mol / L. After rinsing the soaked Forsythia waste to neutral, it was then soaked in a lignin peroxidase solution and heated in a 65 °C water bath for 36.5 min to inactivate the enzyme, thus obtaining enzymatically hydrolyzed Forsythia waste. The concentration of the lignin peroxidase was 0.32 mg / mL, and the enzyme activity was 1167 U / L. The enzymatically hydrolyzed Forsythia waste is dried and then pulverized to obtain the Forsythia adsorbent.

[0019] This invention involves decocting forsythia waste and then soaking it in a calcium chloride solution. In one embodiment, the forsythia waste is dried forsythia branches. In another embodiment, the decoction time is 30 minutes. In yet another embodiment, the decocted forsythia waste is soaked in the calcium chloride solution for 45 minutes.

[0020] The present invention, which involves decocting forsythia waste and then soaking it in a calcium chloride solution, has the following advantages: 1. Disruption of cell structure and promotion of component dissolution: Decoction can use heat to destroy the plant cell walls and fiber structure of forsythia stalks. This makes it easier for subsequent chemical reagents (calcium chloride) and enzymes (lignin peroxidase) to penetrate into the material, improving the modification efficiency.

[0021] 2. Remove impurities and activate the surface: The boiling process can remove some impurities, soluble sugars or small organic molecules attached to the surface of the dead branches, thereby exposing more active sites and creating better contact conditions for subsequent chemical modification and enzyme treatment.

[0022] 3. Improve pore structure: Through boiling treatment, the originally compact wood fiber structure becomes loose, which helps to form more pores during the subsequent drying process, thereby increasing the specific surface area of ​​the adsorbent.

[0023] When treating forsythia stalks, calcium chloride can draw moisture from the stalks, causing cell wall swelling and corrosion. During the subsequent drying process, this helps form a rich microporous and mesoporous structure within the material. Furthermore, the introduction of calcium chloride can alter the chemical environment of the forsythia surface. The presence of calcium ions can sometimes act as a cross-linking agent or change the surface charge distribution, indirectly affecting the adsorption affinity for TVOC molecules. Calcium chloride can provide a suitable ionic environment for lignin peroxidase or stabilize the enzyme's structure, thereby assisting the enzyme in better degrading lignin and exposing more adsorption sites.

[0024] After obtaining the soaked Forsythia waste, the present invention rinses the soaked Forsythia waste until neutral and then soaks it in a lignin peroxidase solution. After heating in a 65°C water bath for 36.5 min, enzyme inactivation treatment is performed to obtain enzymatically hydrolyzed Forsythia waste. As one embodiment, the enzyme inactivation treatment method includes: heating in a 75-100°C water bath to inactivate the enzyme.

[0025] The present invention rinses the soaked forsythia waste until it is neutral, which has the following effect: 1. Removal of residual chemical reagents: After soaking in calcium chloride, a large amount of salt solution will adhere to the surface of Forsythia suspensa. If the excess calcium chloride is not rinsed off, the residual salt will crystallize during the drying process, clogging the newly formed micropores and reducing the adsorption efficiency.

[0026] 2. Adjusting the pH environment: The activity of lignin peroxidase is highly dependent on a specific pH value. Calcium chloride solution is weakly acidic or alkaline. If the enzyme solution is added directly without rinsing to neutral, the excessively acidic or alkaline environment may cause the enzyme to be inactivated or denatured, thus failing to effectively degrade lignin.

[0027] 3. To prevent interference with subsequent reactions: A second rinse to neutral pH after enzyme treatment removes enzyme residue and reaction byproducts. This ensures the final adsorbent surface is pure, preventing residual chemicals or enzyme proteins from occupying adsorption sites, thus guaranteeing maximum adsorption capacity for TVOCs.

[0028] After obtaining the enzymatically hydrolyzed Forsythia waste, the present invention washes the enzymatically hydrolyzed Forsythia waste until neutral, dries it, and then pulverizes it to obtain the Forsythia adsorbent. As one embodiment, the particle size of the Forsythia adsorbent is ≤40 mesh (i.e., passing through a 40-mesh sieve and collecting the undersize). As one embodiment, the drying temperature is 80 °C.

[0029] This invention utilizes calcium chloride and lignin peroxidase to treat dead branches of Forsythia suspensa, resulting in an adsorbent with the best adsorption effect on TVOC. Specific preparation conditions further enhance the adsorption effect of the Forsythia suspensa adsorbent on TVOC (measured maximum value 19.20%). Fourier transform infrared spectroscopy shows a significant change in the number of hydroxyl groups in the prepared Forsythia suspensa adsorbent, indicating their participation in TVOC adsorption. The change in C=C indicates that the optimized Forsythia suspensa alters its functional group structure. Adsorption thermodynamic results show that H0>0 and G0<0, indicating that the adsorption process of TVOC by the Forsythia suspensa adsorbent is a spontaneous endothermic process, with an adsorption fitting coefficient close to 1, consistent with its thermodynamic equation.

[0030] This invention, through structural characterization of the Forsythia suspensa adsorbent after TVOC adsorption, reveals that the treated Forsythia suspensa has a large specific surface area and a porous surface, exhibiting excellent adsorption conditions. During adsorption, groups such as -OH play a significant role. The adsorption process conforms to pseudo-second-order kinetics and the Freundlich isotherm, exhibiting a physicochemical mixed adsorption process dominated by chemistry. It involves adsorption at heterogeneous sites within a multilayer molecular layer and is a spontaneously occurring endothermic reaction. After 21 hours, the adsorption concentration reaches the national standard of 0.6 mg / m³. 3 The Forsythia suspensa adsorbent showed significantly better adsorption performance for TVOC at the 1% level than diatomaceous earth (powder), activated carbon (granules), bamboo charcoal, D101 macroporous adsorption resin, and raw Forsythia suspensa. Even after eight desorption and regeneration cycles, the Forsythia suspensa adsorbent still exhibited a certain adsorption effect on TVOC, demonstrating its excellent recyclability and potential utilization. This invention not only provides a good adsorbent material for treating TVOC in the air but also realizes the utilization of Forsythia suspensa branches as waste.

[0031] This invention provides the application of the Forsythia suspensa adsorbent described in the above technical solution in the adsorption of total volatile organic compounds.

[0032] In one embodiment, the ambient temperature for the Forsythia suspensa adsorbent to adsorb total volatile organic compounds (TVOCs) is 24°C and the humidity is 45%RH. In another embodiment, the adsorption time for TVOCs by the Forsythia suspensa adsorbent is ≥150 min. In yet another embodiment, the concentration of TVOCs by the Forsythia suspensa adsorbent is ≤1.6 mg / m³. 3 The ratio of Forsythia suspensa adsorbent to the adsorption space is 2 g: 1 m 3 .

[0033] The present invention found that the amount of Forsythia suspensa adsorbent added was 2 g / m 3 Particle size 40 mesh, temperature 24 ℃, adsorption time 150 min, initial TVOC concentration 1.6 mg / m³ 3 At a humidity of 45%RH, the Forsythia suspensa adsorbent has the best effect on TVOC removal.

[0034] To further illustrate the present invention, the following detailed description, in conjunction with embodiments and accompanying drawings, provides a Forsythia suspensa adsorbent provided by the present invention and its application in the adsorption of total volatile organic compounds, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0035] 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.; lignin peroxidase (enzyme activity 1167 U / L) was purchased from Zhejiang Tianhe Food Biotechnology Co., Ltd.; resin was purchased from Fuzhou Likang Environmental Protection Technology Co., Ltd.; and activated carbon (analytical grade) was also used. granules), diatomaceous earth (analytical grade) The powder and bamboo charcoal were purchased from Tianjin Ruijinte Chemicals Co., Ltd., and the paint was purchased from Libang Hongcheng Coatings Co., Ltd.

[0036] Methods for determining adsorbed TVOC 1. Determination of removal rate by modified method: The experiment was conducted simultaneously in five identical sealed chambers. Forsythia suspensa residue was placed in each chamber, and then paint was diluted to simulate an environment with excessive TVOC levels. A handheld multi-functional gas detector was used to measure the indoor TVOC content and record the adsorption rate of TVOC by the Forsythia suspensa residue.

[0037] 2. Determination of empty box leakage rate N0: Quickly place the TVOC detector and the container containing the paint sample into a sealed box, and immediately seal the box opening. When the detector reading n0 no longer changes, indicating that the TVOC concentration has reached equilibrium, quickly remove the container containing the paint sample and start timing simultaneously. Record the detector value (n) after the set time. At this point, the empty box leakage rate (N0) = n0 - n.

[0038] 3. Determination of TVOC adsorption rate N: First, place the TVOC detector and the container containing the paint sample into a sealed box, and immediately seal the box. Wait until the paint has spread sufficiently and the detector reading does not change; record this as n1. Remove the paint culture dish, replace it with a culture dish evenly covered with forsythia suspensa residue, and place it in the same position. Set the adsorption time. After timing, record the reading n2. The formula for calculating the adsorption rate (N) is as follows: N = (n1 - n2) / (n1 - N0) × 100%, where N0 is the empty box leakage rate.

[0039] Example 1 Forsythia suspensa dead branches were treated with calcium chloride and lignin peroxidase. The ability of the treated Forsythia suspensa to remove TVOC was tested, as follows: Cleaning: Rinse 30 g of dried forsythia branches under running water; Boiling: Boil the dried forsythia branches in a pot for 30 minutes; Prepare 0.1 mol / L calcium chloride solution by soaking forsythia suspensa dead branches for 45 min, then rinsing the branches until neutral. Prepare lignin peroxidase solutions of 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL, and 0.5 mg / mL. Soak equal portions of forsythia suspensa dead branches separately and incubate in a 65 ℃ water bath for 30 min. Inactivate the enzyme in a 75 ℃ water bath for 10 min. Rinse the forsythia suspensa dead branches with water until neutral and dry them in a dryer at 80 ℃. Pass the pulverized residue through a 40-mesh sieve and collect the sieve-passing material, then pack it into resealable bags.

[0040] The test results of the TVOC removal capacity of the treated Forsythia are shown in the figure. Figure 1 .

[0041] Yield = Mass of modified Forsythia suspensa residue / Mass of original Forsythia suspensa dead branches 100%.

[0042] Q = (C0 - C) V / m; Where Q: adsorption capacity (mg / g); C0: initial concentration of TVOC (mg / m³) 3 C: TVOC concentration after adsorption (mg / m³) 3 V: Volume of the experimental chamber (m³) 3 m: Amount of Forsythia suspensa residue added (g).

[0043] Depend on Figure 1 It can be seen that the adsorption of Forsythia suspensa residue prepared by the calcium chloride + lignin peroxidase method generally shows an upward trend followed by a decline. When the concentration of lignin peroxidase is increased to 0.4 mg / mL, the removal rate reaches its peak at 14.49%, with a yield of 85%. When the concentration of lignin peroxidase is increased to 0.5 mg / mL, the removal rate is the lowest at only 8.67%, with a yield of 72%.

[0044] Example 2 The optimal calcium chloride + lignin peroxidase method in Example 1 was optimized as follows: 1. The quadratic regression orthogonal rotational combination design was used to optimize the experiment. The level coding table is shown in Table 1.

[0045] Table 1 Horizontal Coding Table

[0046] The optimal preparation conditions for Forsythia suspensa adsorbent for TVOC removal can be obtained using DPS software. Based on these optimal conditions, Forsythia suspensa residue can be prepared in large quantities for further verification.

[0047] 2. Based on optimal preparation conditions, Forsythia suspensa residue was prepared. An environmental factor experiment was conducted to investigate the effects of residue particle size, dosage, temperature, humidity, initial concentration, and time on the removal efficiency of TVOC. The specific experimental design is as follows: 1) Particle size of residue: Forsythia residue was sieved through different mesh sizes, namely 20, 40, 60, 80 and 100 mesh. 2 g of residue of each of the five particle sizes was taken for the experiment (method as above). The value on the detector was recorded after 30 min and the removal rate was calculated.

[0048] 2) Amount of residue added: The optimal residue particle size of 40 mesh was selected for adsorption test: 1 g, 2 g, 3 g, 4 g, and 5 g were weighed; these 5 g values ​​were set as the addition gradient for the experiment. After 30 min, the values ​​on the detector were recorded and the removal rate was calculated.

[0049] 3) Adsorption temperature: Five different temperature gradients were set for the adsorption environment: 20 ℃, 22 ℃, 24 ℃, 26 ℃ and 28 ℃. 2 g of Forsythia suspensa residue was taken, and the value on the detector was recorded after 30 min. The removal rate was then calculated.

[0050] 4) Adsorption humidity: Set five humidity gradients of 40%RH, 45%RH, 50%RH, 55%RH and 60%RH respectively. Take 2 g of Forsythia suspensa residue, record the value on the detector after 30 min and calculate its removal rate.

[0051] 5) Initial concentration: The initial concentration of TVOC gas in the chamber was kept constant at 1.6 mg / m³. 3 1.7 mg / m 3 1.8 mg / m 3 1.9 mg / m 3 2.0 mg / m 3 Take 2 g of Forsythia suspensa residue, record the value on the detector after 30 minutes, and calculate the removal rate. 6) Adsorption time: Take 2 g of 40 mesh sample and adsorb for 30 min, 60 min, 90 min, 120 min and 150 min respectively. Record the detector values ​​at each time point and calculate the removal rate.

[0052] 3. Characterization and analysis of Forsythia suspensa adsorption materials 1) Infrared spectroscopy analysis: This method can detect functional groups on the surface of raw Forsythia suspensa, Forsythia suspensa residue prepared by the optimized method (optimized Forsythia suspensa), and Forsythia suspensa residue after adsorption. Structural analysis of raw, optimized, and adsorbed Forsythia suspensa is also performed. 2) Scanning electron microscopy observation: A relatively systematic microscopic morphology characterization was carried out on raw Forsythia suspensa, optimized Forsythia suspensa, and Forsythia suspensa after adsorption using scanning electron microscopy. 3) Specific surface area and pore size analysis: A specific surface area and pore size analyzer was used to measure relevant parameters of the original Forsythia, optimized Forsythia, and Forsythia after adsorption, such as specific surface area, pore volume, and pore size distribution. 4) Elemental analysis: The content of carbon, hydrogen, sulfur and nitrogen in Forsythia suspensa, as well as the content of carbon, hydrogen, sulfur and nitrogen in the optimized sample and the sample after adsorption, were determined.

[0053] 4. Comparative test of six adsorbents The adsorption effects of raw and optimized Forsythia suspensa on TVOC were compared with those of four materials: bamboo charcoal, activated carbon, diatomaceous earth, and D101 macroporous adsorption resin. Adsorption times were set at 30 min, 60 min, 90 min, 120 min, and 150 min, and three experiments were conducted to ensure the accuracy of the results. The removal rates were calculated.

[0054] 5. Experiment on desorption and recycling of modified Forsythia suspensa residue Desorption regeneration involves changing the operating conditions to detach the adsorbed substance from the surface of the adsorbent, thereby regenerating the adsorbent.

[0055] 6. Results Analysis Table 2. Quadratic Regression Orthogonal Rotational Combination Design Table

[0056] Analysis of the experimental results using DPS software yielded the regression equations relating the concentration of modified Forsythia suspensa lignin peroxidase (X1), calcium chloride concentration (X2), calcium chloride soaking time (X3), and TVOC removal rate (Y): Y=16.66639+0.11812X1-0.16589X2-0.23671X3+0.45934X1 2 +0.72628X2 2 +0.30908X3 2 +0.08875X1X2+0.11125X1X3+0.09125X2X3.

[0057] At a significance level of 0.01, the F-value in the model is... 失拟 =1.408<0.01(5,8)=6.63, indicating that the experimental error is small, F 回归 =5.628>0.01(9,13)=4.19, indicating that the regression equation is significant and highly reliable. The results of the first-order ANOVA are shown in Table 3.

[0058] Table 3. Analysis of First-Order Variance

[0059] Among the three pairs of two-factor interactions, X1X2, X1X3, and X2X3, the influence of X1X3 is more significant.

[0060] The optimal preparation factors for calcium chloride and lignin peroxidase, predicted by the DPS data processing system, are: X1=-1.682, X2=-1.682, X3=-1.682. Under these three factors, the predicted maximum removal effect of Forsythia suspensa is 20.89%. The verified removal rate is 19.20%. The ratio of the two values ​​is 0.92, approximately 1, indicating a good match between the two values, successful verification, and demonstrating the accuracy of the model's prediction.

[0061] The results of the analysis of the effect of slag particle size on the removal of TVOC by Forsythia suspensa are shown in the figure. Figure 2 The different letters represent significant differences between different groups, as shown in the figure below. The results show that the removal efficiency first increases and then decreases with increasing particle size. Different mesh sizes of Forsythia suspensa residue show highly significant differences in TVOC removal rates at the 1% level (F=369.354, P=0.0001<0.01). The removal efficiency of Forsythia suspensa for TVOC reaches its peak at 40 mesh, with a removal rate of 14.29%. Because TVOC is a mixture, increasing the mesh size is actually detrimental to its removal. The removal rate is worst at 100 mesh, at 9.15%.

[0062] The effect of adding certain amounts on the removal of TVOC by Forsythia suspensa is shown in the figure. Figure 3The results showed that the adsorption rate increased with the amount of residue added, reaching a peak of 16.28% at an addition amount (mass of Forsythia suspensa residue added per unit volume of the experimental chamber) of 2 g. There was a highly significant difference in the removal of TVOC by different amounts of Forsythia suspensa residue (F=78.735, P=0.0001<0.01), after which the rate leveled off. An addition amount of 3 g resulted in the second highest rate, while 5 g yielded the worst result at 15.87%.

[0063] The effects of different adsorption temperatures on TVOC removal by Forsythia suspensa are shown in the figure. Figure 4 The results showed that as the temperature continued to rise, the removal of TVOC by Forsythia suspensa residue at different temperatures showed a highly significant difference (F=287.286, P=0.0001<0.01). The removal rate reached its peak at 24 ℃, reaching 14.80%, followed by 26 ℃, and was worst at 20 ℃, at 11.42%.

[0064] The effects of different adsorption humidity levels on TVOC removal by Forsythia suspensa are shown in the figure. Figure 5 The results showed that the removal rate was optimal at 45%RH, with a removal rate of 13.75%. The TVOC removal efficiency of Forsythia suspensa residue showed a highly significant difference of 1% at different humidity levels (F=128.741, P=0.0001<0.01). The removal rate was worst at 50%RH, with a removal rate of 10.55%.

[0065] The results of the analysis of the effect of adsorption time on the removal of TVOC by Forsythia are shown in the figure. Figure 6 The results showed that the interaction between Forsythia suspensa residue and TVOC removal efficiency at different temperatures and times reached a highly significant level (F0.05). 时间 =45.866, P=0.0001<0.01; F 温度 =44.147, P=0.0001<0.01; F 时间×温度 =13.391, P=0.0001<0.01). Forsythia showed the best removal effect on TVOC at an adsorption time of 150 min, with removal rates of 25.85%, 28.13%, and 19.38% at 26 ℃, 28 ℃, and 30 ℃, respectively. The worst removal effect was observed at 30 min, with removal rates of 13.55%, 14.32%, and 11.37%.

[0066] The results of the analysis of the effect of initial concentration on the removal of TVOC by Forsythia are shown in the figure. Figure 7 The results showed that the interaction between Forsythia suspensa at different temperatures and different initial concentrations on the removal effect of TVOC reached a highly significant level of 1% (F0). 浓度 =28.702, P=0.0001<0.01; F 温度=60.901, P=0.0001<0.01; F 浓度×温度 =0.432, P=0.0001<0.01). The initial concentration was 1.6 mg / m³. 3 Forsythia showed the best removal effect on TVOC, with removal rates of 17.71%, 19.12%, and 16.81% at 26 ℃, 28 ℃, and 30 ℃, respectively, at an initial concentration of 2 mg / m³. 3 The results were the worst, with removal rates of 14.97%, 16.28%, and 14.85%.

[0067] Infrared spectra of different Forsythia suspensa species are shown below. Figure 8 The results showed that at 3400cm -1 It exhibits stretching vibrations of -OH, indicating a high concentration of hydroxyl groups; at a wavenumber of 2900 cm⁻¹. -1 ~3000 cm -1 At the location, there is a saturated CH stretching vibration, indicating the presence of a large number of saturated hydrocarbon groups; the changes in the intensity and position of the partial absorption peaks of the Forsythia suspensa adsorbent before and after optimization indicate that optimization affects the number, form, or chemical environment of its functional groups.

[0068] Table 4 Elemental Analyzer Analysis Table

[0069] Elemental analysis revealed that the modified Forsythia prepared in this invention has a more optimized chemical composition after modification (Table 4). Infrared spectroscopy confirmed that the modified Forsythia is a porous active material with strong adsorption capacity due to the change in hydroxyl groups.

[0070] The analysis results of different Forsythia electron microscope lenses are shown below. Figure 9 The images, from left to right, represent the original Forsythia suspensa, modified Forsythia suspensa, and Forsythia suspensa after adsorption, with a scale bar of 10 μm in the lower right corner. The results show that the original Forsythia suspensa has an uneven surface with many pores, while the modified Forsythia suspensa has increased pores and exhibits multiple wrinkles compared to the original. The Forsythia suspensa after adsorption is much smoother and more regular than the original, demonstrating that the pores are filled with adsorbents. Overall, the modified Forsythia suspensa has a significant effect on the removal of TVOCs.

[0071] The results of the specific surface area parameter analysis are shown in Table 5.

[0072] Table 5 Specific Surface Area Analysis Table

[0073] The results showed that the optimized specific surface area of ​​Forsythia suspensa was 4.374 m². 2 / g, pore volume 0.006 cm³ 3 / g, and a pore size distribution of 3.261d further confirm that after optimization treatment, Forsythia suspensa has more adsorption sites and can effectively adsorb Forsythia suspensa.

[0074] The comparison results of the adsorption effects of different adsorbent materials on TVOC are shown in the figure. Figure 10 Different letters indicate significant differences in the adsorption effect of different adsorbents on TVOC at the same time. The results show that, at the same temperature of 28 ℃ and humidity of 45%RH, the TVOC removal effects of modified Forsythia suspensa and different adsorbents showed extremely significant differences (F0.05) at the 1% level for both different materials and different times. 材料= 225.011 ， P = 0.0001 < 0.01; F 时间 =40.871, P=0.0001<0.01; F 材料×时间 =738.948, P=0.0001<0.01). Analysis of the differences among different materials shows that modified Forsythia suspensa significantly outperformed other adsorbents at the 1% level in TVOC removal rate. The order was: modified Forsythia suspensa > diatomaceous earth (powder) > activated carbon > bamboo charcoal > D101 macroporous adsorption resin > virgin Forsythia suspensa, with diatomaceous earth being the second best, and virgin Forsythia suspensa branches showing the worst TVOC removal effect.

[0075] The adsorption effects of different adsorbent materials on TVOC are shown in Table 6 by two-way ANOVA, and the results of multiple comparisons are shown in Table 7.

[0076] Table 6 Two-way ANOVA

[0077] Table 7 Multiple Comparison Table

[0078] As shown in Table 7, the removal effect varies significantly depending on the adsorption material and the reaction time. Among all the materials, modified Forsythia shows a particularly outstanding removal effect compared to the other five materials, with a very significant advantage.

[0079] The results of desorption and recycling are shown in Figure 11 The results showed that with the increase of desorption cycles, the removal efficiency of Forsythia suspensa adsorbent reached a highly significant difference at the 1% level (F=186.731, P=0.0001<0.01). The first removal rate was 17.36%, at which point the adsorption capacity of Forsythia suspensa was strongest. The removal rate decreased gradually from the fourth to the fifth cycles, and although it decreased, it still maintained a good adsorption effect. From the seventh to the eighth cycles, the removal rate decreased gradually, indicating that after multiple adsorption cycles, the number of adsorption sites was greatly reduced and the adsorption capacity was significantly reduced. However, Forsythia suspensa still had a certain removal effect and could be recycled and reused multiple times.

[0080] Adsorption kinetic curve Adsorption kinetics studies focus on characterizing the rate at which adsorbents adsorb solutes, using pseudo-first-order and pseudo-second-order kinetic models to fit experimental data and deeply analyze the intrinsic mechanisms of the adsorption process.

[0081] The pseudo-first-order dynamic equation is: lgQ-lg(Q-q) =k1t / 2.303; The pseudo-second-order dynamic equation is: t / q-t / Q =1 / (k2·Q) 2 ); In the formula: the adsorption amount at time t is q (mg / g), the equilibrium adsorption amount is Q (mg / g), and k1 and k2 are the first-order and second-order adsorption kinetic constants (g·mg), respectively. -1 ·min -1 ).

[0082] The effect of adsorption time on the adsorption capacity of Forsythia suspensa residue is shown in the following results. Figure 12 The pseudo-first-order and pseudo-second-order kinetic parameters are shown in Table 8. The fitting results of the pseudo-first-order kinetic equations are shown in... Figure 13 The fitting results of the pseudo-second-order dynamic equations are shown in Figure 14 The results showed that under the influence of three temperatures (26℃, 28℃, and 30℃), the coefficients of the pseudo-first-order kinetic equation were 0.9868, 0.9337, and 0.9005, respectively, with corresponding equations of y = -0.0088x - 1.7433, y = -0.0108x - 1.5643, and y = -0.0058x - 2.0317. The coefficients of the pseudo-second-order kinetic equation were 0.9942, 0.9898, and 0.9508, with corresponding equations of y = 40.447x + 2268.7, y = 37.565x + 2206, and y = 59.032x + 2668.3. This indicates that the adsorption process of TVOC by Forsythia suspensa conforms to the pseudo-second-order kinetic model. Based on the mechanism established by the pseudo-second-order kinetic equation, it is speculated that during the adsorption of TVOC by Forsythia suspensa, the TVOC concentration after 21 hours is lower than the national standard of 0.6 mg / m³. 3 The kinetic relationship R of the pseudo-second-order equation fitting at three temperatures: 26 ℃, 28 ℃, and 30 ℃. 2 A value greater than 0.9 strongly suggests that the Forsythia suspensa adsorbent exhibits TVOC adsorption behavior, and from the perspective of adsorption state, it tends to be an adsorption mode of multilayer adsorption.

[0083] Table 8. Pseudo-first-order and pseudo-second-order dynamic parameters

[0084] Adsorption isotherm The linear equations for the Langmuir model and the Freundlich model are as follows: Langmuir model: C / Q m+1 / Q m b = C / Q; Freundlich model: K·C 1 / n =Q; Taking the logarithm and placing it on both sides of the Freundlich model, the transformed form is: lgK+(1 / n)lgC =lgQ; Where: equilibrium concentration C (mg / m³) 3 The adsorption equilibrium constant b indicates the binding force of the adsorbent to the adsorbate. Q refers to the equilibrium adsorption capacity (mg / g), Qm refers to the saturated adsorption capacity (mg / g), and K and 1 / n (0 < 1 / n < 1) refer to constants at temperature.

[0085] Adsorption capacity calculation formula: Q = (C0 - C)V / m; With equilibrium concentration c (mg / m³) 3 The x-axis represents the adsorption capacity q (mg / m³). 3 Plot the adsorption isotherm curve with y as the ordinate axis.

[0086] The relationship between the initial VOC concentration and the adsorption capacity is shown in the figure. Figure 15 The Langmuir isotherm can be seen Figure 16 The Freundlich isotherm can be found here. Figure 17 The parameters of the adsorption isotherm model are shown in Table 9. The results show that the relationship Ri of the adsorption isotherms fitted by the Freundlich equation at three temperatures: 26 ℃, 28 ℃, and 30 ℃. 2 A value greater than 0.9 strongly suggests that the Forsythia suspensa adsorbent exhibits strong adsorption behavior for TVOCs. From the perspective of the adsorption state, it tends to be a multilayer adsorption mode, with the adsorption process being mainly chemical adsorption.

[0087] Table 9 Parameters of the Adsorption Isotherm Model

[0088] Adsorption thermodynamics Adsorption free energy change ( G0), adsorption enthalpy change ( H0) and entropy change ( Thermodynamic parameters such as S0 are calculated using the following formula: ; ; in, G0: Standard Gibbs free energy, in units of... kJ / mol; R: thermodynamic gas constant; T: thermodynamic temperature, unit K; H0: enthalpy change of the reaction, in kJ / mol; S0: Entropy variable, in units of J / mol·K; Kc: Thermodynamic equilibrium constant.

[0089] Plot the adsorption thermodynamic curve with temperature (°C) on the x-axis and adsorption amount q (mg / g) on ​​the y-axis.

[0090] The effect of adsorption temperature on TVOC adsorption efficiency is shown in the following results. Figure 18 The fitting results of the adsorption thermodynamic equation are shown in [the table]. Figure 19 Thermodynamic parameters are shown in Table 10. The results show that the enthalpy change (ENT) during the adsorption process of TVOC by the Forsythia suspensa adsorbent is significant. H0) is greater than zero, the free energy change ( Since G0) is less than zero, it can be determined that the adsorption process is spontaneous and endothermic. The correlation coefficient R of the fitted thermodynamic curve is... 2 The value is close to 1, indicating a high degree of fit with the thermodynamic equation. This result suggests that the adsorption of TVOC by the Forsythia suspensa adsorbent conforms to thermodynamics.

[0091] Table 10 Thermodynamic parameters

[0092] In summary, with a calcium chloride concentration of 0.02 mol / L, a water bath time of 36.5 min, and a lignin peroxidase concentration of 0.32 mg / mL, the measured maximum value of 19.20% is consistent with the theoretical value of Y. max Compared to 20.89%, the actual value / model optimum = 0.92. This was achieved with an addition of 2 g, a residue particle size of 40 mesh, a temperature of 24 ℃, an adsorption time of 150 min, and an initial concentration of 1.6 mg / m³. 3 At a relative humidity of 45% RH, Forsythia suspensa adsorbent showed the best removal effect for TVOC. Structural characterization revealed that the treated Forsythia suspensa had a large specific surface area and a loose, porous surface, providing excellent adsorption conditions. During adsorption, groups such as -OH played a role; the adsorption process conformed to pseudo-second-order kinetics and the Freundlich isotherm, exhibiting a physicochemical mixed adsorption process dominated by chemistry. This involved adsorption at heterogeneous sites within a multi-molecular layer and a spontaneous endothermic reaction, achieving the national standard of 0.6 mg / m³ after 21 hours. 3 The modified Forsythia suspensa showed significantly better TVOC adsorption performance at the 1% level than diatomaceous earth (powder), activated carbon (granules), bamboo charcoal, D101 macroporous adsorption resin, and the original Forsythia suspensa. Even after eight desorption and regeneration cycles, the Forsythia suspensa adsorbent still exhibited a certain adsorption effect on TVOC.

[0093] 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 forsythia adsorbent, characterized in that, The method for preparing the Forsythia suspensa adsorbent includes the following steps: The waste forsythia was boiled and then soaked in a calcium chloride solution with a concentration of 0.02 mol / L. After rinsing the soaked Forsythia waste to neutral, it was then soaked in a lignin peroxidase solution and heated in a 65 ℃ water bath for 36.5 min to inactivate the enzyme, thus obtaining enzymatically hydrolyzed Forsythia waste; the concentration of the lignin peroxidase was 0.32 mg / mL; and the enzyme activity of the lignin peroxidase was 1167 U / L. The enzymatically hydrolyzed Forsythia waste is dried and then pulverized to obtain the Forsythia adsorbent.

2. The Forsythia adsorbent according to claim 1, characterized in that, The particle size of the Forsythia adsorbent is ≤40 mesh.

3. The Forsythia suspensa adsorbent according to claim 1, characterized in that, The waste from decocting Forsythia suspensa was soaked in calcium chloride solution for 45 minutes.

4. The Forsythia adsorbent according to claim 1 or 3, characterized in that, The forsythia waste is forsythia dead branches.

5. The Forsythia adsorbent according to claim 1, characterized in that, The enzyme inactivation treatment method includes: heating the enzyme in a water bath at 75~100℃.

6. The Forsythia adsorbent according to claim 1, characterized in that, The drying temperature is 80 ℃.

7. The use of the Forsythia suspensa adsorbent according to any one of claims 1 to 6 in the adsorption of total volatile organic compounds.

8. The application according to claim 7, characterized in that, The Forsythia suspensa adsorbent is used in an environment with an ambient temperature of 24°C and a humidity of 45%RH when adsorbing total volatile organic compounds.

9. The application according to claim 7, characterized in that, The adsorption time of the Forsythia suspensa adsorbent when adsorbing total volatile organic compounds is ≥150 min.

10. The application according to claim 7, characterized in that, The Forsythia suspensa adsorbent has a total volatile organic compound (TVC) concentration ≤ 1.6 mg / m³ when adsorbing TVC. 3 The ratio of Forsythia suspensa adsorbent to the adsorption space is 2 g: 1 m 3 .

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