Modified reed adsorbent, preparation method and application of modified reed adsorbent in malachite green adsorption

Abstract

The invention belongs to the field of environmental protection, and particularly relates to a modified reed adsorbent, a preparation method and application of the modified reed adsorbent in malachite green adsorption. The modified reed adsorbent obtained by combining calcium oxide with amylase treatment has good adsorption performance when being applied to adsorption of malachite green. Particularly, for a to-be-adsorbed solution with the malachite green concentration of about 10 mg / L, the adsorption rate can reach 90% or above by adjusting the crushing particle size, the adsorption temperature, the addition amount, the pH and the adsorption time of the modified reed adsorbent, meanwhile, the desorption and regeneration capacity is excellent, and the adsorption capacity can still reach 70% or above after three times of desorption and regeneration.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection, specifically relating to a modified reed adsorbent, its preparation method, and its application in malachite green adsorption. Background Technology

[0002] Dyeing and printing wastewater refers to the wastewater discharged during the pretreatment, dyeing, printing, and finishing of cotton, wool, linen, silk, chemical fiber, or blended products. It contains dyes, auxiliaries, and other substances, posing significant hazards to the environment and human health. When this wastewater is discharged into natural water bodies, it can have toxic effects on aquatic organisms, affecting their growth. Dyeing and printing wastewater may also contain various harmful substances; these compounds are highly toxic to organisms, can interfere with normal physiological functions, and cause ecological risks.

[0003] Malachite green, also known as basic green or base green, belongs to the triphenylmethane dye family. It is chemically stable and difficult to degrade. Malachite green residues in the aquatic environment can cause serious water pollution. It also reduces photosynthesis by blocking light penetration, hindering the normal growth of aquatic organisms. After entering aquatic organisms and crops, malachite green accumulates in the human body through the food chain, causing diseases such as high blood pressure, kidney failure, and convulsions. Malachite green in aquatic bodies negatively impacts aquatic ecosystems, affecting the survival and reproduction of aquatic organisms.

[0004] Currently, the treatment methods for dyeing and printing wastewater containing malachite green generally include three types: physical treatment, chemical treatment, and biological treatment. Physical adsorption utilizes adsorbents with porous structures and large specific surface areas (such as activated carbon, diatomaceous earth, and molecular sieves) to achieve surface adhesion of dye molecules and other organic pollutants. Examples show that although activated carbon exhibits good adsorption efficiency for most dyes, its high cost is a limiting factor in its application. In contrast, natural adsorbents such as clay and straw, while widely available and inexpensive, have significantly insufficient adsorption capacity. Commonly used chemical treatment methods include advanced oxidation processes and coagulation. Therefore, these methods do indeed have significant removal effects on recalcitrant organic pollutants. However, the high treatment cost and potential secondary pollution cannot be ignored. The metabolic function of aerobic microorganisms plays a crucial role in biological treatment. This function facilitates the conversion of organic pollutants into carbon dioxide and water. Activated sludge and biofilm processes constitute common aerobic biological treatment process systems. Examples show that this type of process is highly effective in treating biodegradable dyeing and printing wastewater, but it exhibits significant limitations when dealing with certain recalcitrant organic matter.

[0005] Therefore, a green, convenient, and low-cost method for treating malachite green is needed in this field. Summary of the Invention

[0006] Based on the above factors, this application provides a modified reed adsorbent, a preparation method, and its application in the adsorption of malachite green. The reed adsorbent obtained by this preparation method has a greatly enhanced adsorption effect on malachite green in wastewater.

[0007] To achieve the above objectives, the first technical solution of this application discloses a method for preparing a modified reed adsorbent, which includes soaking boiled reeds in a calcium chloride solution, taking them out and washing them, then placing them in a water bath in an amylase solution, and finally taking them out, washing them until neutral, and drying them to obtain the adsorbent.

[0008] Preferably, the concentration of the calcium chloride solution is 0.1 mol / L, and the concentration of the amylase solution is 0.3 g / L to 0.5 g / L.

[0009] Preferably, the water bath temperature for the amylase solution water bath treatment is 40-60℃.

[0010] And the modified reed adsorbent obtained according to the above preparation method.

[0011] The second technical solution of this application discloses the application of the modified reed adsorbent described in the first technology in the adsorption of malachite green, including the following steps: after crushing the modified reed adsorbent, it is placed in the solution to be adsorbed containing malachite green, and the pH of the solution is adjusted before adsorption.

[0012] Preferably, the modified reed adsorbent is pulverized to a particle size of 80-100 mesh.

[0013] Preferably, the adsorption temperature is 20-50℃.

[0014] Preferably, the modified reed adsorbent is added at a rate of 0.2-0.8 g / 100 mL.

[0015] Preferably, the pH is adjusted to 8-10.

[0016] Preferably, the adsorption time is ≥60 min.

[0017] Beneficial effects: This application modifies reeds, making the modified reed adsorbent more porous with significantly increased wrinkles, providing more adsorption sites for the adsorption process. Using this modified reed adsorbent to adsorb malachite green in water, the maximum removal rate can reach over 90%, and it exhibits excellent desorption and regeneration capabilities; even after three adsorption and desorption cycles, the adsorption rate of malachite green can still reach over 70%. Attached Figure Description

[0018] Figure 1 A standard absorbance curve of malachite green;

[0019] Figure 2The effect of NaOH concentration on adsorption efficiency during alkaline hot blanching;

[0020] Figure 3 The effect of calcium chloride + amylase treatment on adsorption efficiency;

[0021] Figure 4 The effect of ferric chloride + ligninase treatment on adsorption efficiency;

[0022] Figure 5 Effects of ethyl acetate + cellulase + hemicellulase treatment on adsorption efficiency

[0023] Figure 6 The effect of the particle size of the modified reed adsorbent on adsorption;

[0024] Figure 7 The effect of the amount of modified reed adsorbent added on adsorption;

[0025] Figure 8 The effect of the initial concentration of malachite green solution on adsorption;

[0026] Figure 9 The effect of adsorption time on adsorption;

[0027] Figure 10 The effect of adsorption temperature on adsorption;

[0028] Figure 11 The effect of pH on adsorption;

[0029] Figure 12 The graph shows the interaction effect between the adsorption concentration (X1) and the amount added (X3).

[0030] Figure 13 Comparison of scanning electron microscope images of three types of reeds;

[0031] Figure 14 Infrared spectra of three types of reeds;

[0032] Figure 15 This is an isotherm graph;

[0033] Figure 16 For Langmuir model;

[0034] Figure 17 For Freundlich (Flanderich model);

[0035] Figure 18 Adsorption kinetic curves of malachite green adsorbent by modified reed adsorbent

[0036] Figure 19 The curve is a quasi-first-order rate equation.

[0037] Figure 20 The curve is a quasi-second-order rate equation.

[0038] Figure 21 The effect of different temperatures on the adsorption of malachite green by modified reed adsorbent;

[0039] Figure 22 Thermodynamic curves of malachite green adsorption by modified reed adsorbent;

[0040] Figure 23 Analysis of the removal effects of different adsorbent materials on malachite green;

[0041] Figure 24 This is a diagram showing the desorption and regeneration of the modified reed adsorbent. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0044] Unless otherwise specified, the technical terms in this specification have the same meaning as those generally understood by those skilled in the art; however, in case of any conflict, the definitions in this specification shall prevail.

[0045] Example 1: Selection of Preparation Method for Modified Reed Adsorbent

[0046] This embodiment studies the preparation method of modified reed adsorbent and determines the optimal treatment method for reed modification.

[0047] Experimental method: Take 50g of reeds (the reeds are taken from around the salt lake in the salt lake area of ​​Yuncheng City), put them in boiling water and boil for 30 minutes, then take them out and treat them using the following four methods.

[0048] a. Alkali heat treatment: Prepare NaOH solutions of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, and 0.5 mol / L. Place the treated reeds in the NaOH solutions of different concentrations in a water bath for 30 minutes at a temperature of 60℃.

[0049] b. Calcium chloride + amylase treatment: Prepare a 0.1 mol / L calcium chloride solution and soak the reeds in it for 2 hours. Then prepare amylase solutions of 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, and 0.5 g / L respectively. Wash the soaked reeds and divide them into five equal portions. Place each portion into a water bath at 50°C for 30 minutes. After treatment, raise the water bath temperature to 80°C and perform enzyme inactivation treatment for 20 minutes.

[0050] c. Ferric chloride + ligninase treatment: Prepare a 0.1 mol / L ferric chloride solution and soak the reeds in it for 2 hours. Then prepare ligninase solutions of 4 mg / L, 8 mg / L, 12 mg / L, 16 mg / L, and 20 mg / L respectively. Wash the soaked reeds and divide them into five equal portions. Put them into the above ligninase solutions of different concentrations respectively. After adjusting the water bath to 55°C, put them in the water bath for 30 minutes. Then raise the water bath temperature to 75°C and perform enzyme inactivation treatment for 10 minutes.

[0051] d. Ethyl acetate + cellulase + hemicellulase treatment: Prepare a 0.1 mol / L ethyl acetate solution and soak the reeds in it for 24 hours. Mix cellulase and hemicellulase in a 1:1 ratio to prepare double enzyme solutions with concentrations of 1 g / L, 2 g / L, 3 g / L, 4 g / L, and 5 g / L. Wash the soaked reeds and divide them into five equal portions. Place each portion into a double enzyme solution of different concentrations. Set the water bath to 50°C and place the reeds in the water bath for 30 minutes. Then raise the water bath temperature to 75°C and perform enzyme inactivation treatment for 20 minutes.

[0052] The reeds treated by the above four methods were washed until neutral, and then dried in an oven at 80°C. After drying, the reeds were crushed and sieved through a 100-mesh sieve to obtain modified reed adsorbents a, b, c, and d, which were then sealed and stored.

[0053] The modified reed adsorbents a, b, c, and d were subjected to adsorption tests on solutions containing malachite using the absorbance method. Specifically:

[0054] 1. Plotting the malachite green standard curve: Weigh 0.1g of solid malachite green to prepare a 100mg / L malachite green stock solution; use the stock solution to prepare malachite green solutions with concentrations of 0.5mg / L, 1mg / L, 2mg / L, 3mg / L, 4mg / L, 6mg / L, 8mg / L, and 10mg / L respectively; adjust the wavelength of the UV-Vis spectrophotometer to 619nm and measure the absorbance of the above 8 solutions; repeat the experiment three times and take the average value; plot the malachite green standard curve based on the measurement data.

[0055] The obtained malachite green concentration and absorbance data are shown in Table 1, and the standard curve is shown in Table 2. Figure 1 As shown, the standard curve equation for malachite green obtained is y = 0.1289x - 0.0168, R² = 0.9993. This indicates that the numerical value and the predicted value show a consistent trend.

[0056] Table 1. Malachite Green Concentration and Absorbance Data

[0057]

[0058] 2. Using the absorbance method, prepare 1000 mL of 10 mg / L malachite green solution. Pour 50 mL into 20 small beakers, add 0.1 g of each of the 20 optimized reeds prepared using four different treatment methods, adjust the pH to 7, and allow adsorption to occur at room temperature for 1 hour. Collect the supernatant. Adjust the wavelength of the UV-Vis spectrophotometer to 619 nm and measure the absorbance.

[0059] Removal rate calculation formula: Removal rate = (C0 - C) × 100% / C0;

[0060] Adsorption capacity calculation formula: q=(C0-C)×V / M;

[0061] Where: C0 is the initial concentration of malachite green (mg / L); C is the equilibrium concentration after adsorption (mg / L); q is the adsorption amount (mg / g); V is the volume of malachite green solution (L); and M is the mass of reed residue added (g).

[0062] Experimental results: such as Figure 2-5 The figure shows the adsorption analysis of malachite green by 20 optimized reeds obtained from four treatment methods. Figure 2 To investigate the effect of NaOH concentration on adsorption efficiency during alkaline hot blanching, the following analysis was conducted. Figure 2 It can be seen that as the NaOH concentration increases, the removal rate of malachite green by reeds first increases and then decreases. The reason is speculated to be that excessively high concentrations of NaOH are highly corrosive and will excessively damage the reed structure, reducing its adsorption capacity. When the NaOH concentration is 0.3 mol / L, the removal rate reaches the highest value of 73%.

[0063] Figure 3 The effect of calcium chloride + amylase treatment on adsorption efficiency was investigated. Figure 3 It was found that as the amylase concentration increased, the removal rate of malachite green by reeds first increased and then decreased. This is presumably because when the amylase concentration is too high, excessive enzyme molecules aggregate and occupy the active sites on the reed surface, hindering the binding of malachite green to these sites and thus reducing the removal rate. The removal rate reached its highest value of 73.5% when the amylase concentration was 0.4 g / L.

[0064] Figure 4 The effect of ferric chloride + ligninase treatment on adsorption efficiency was investigated. Figure 4 It was found that the removal rate of malachite green by reeds first increased and then decreased with increasing ligninase concentration. This is presumably because excessively high ligninase concentrations may trigger excessive degradation of other components in the reeds, and the resulting degradation products compete with malachite green for adsorption sites, leading to a decrease in the amount of malachite green adsorbed and a lower removal rate. The removal rate reached its highest value of 46.2% when the ligninase concentration was 16 mg / L.

[0065] Figure 5 The effect of ethyl acetate + cellulase + hemicellulase treatment on adsorption efficiency was investigated. Figure 5 It can be seen that as the concentration of the two enzymes increases, the removal rate of malachite green by reeds first increases and then decreases. This is presumably because at high concentrations, the two enzymes may interact, leading to a decrease in the removal rate. The removal rate reaches its highest value of 73.3% when the concentration of the two enzymes is 3 g / L.

[0066] Based on the above data comparison and analysis, the optimal removal rate of malachite green was achieved when the amylase concentration was 0.4 g / L in the calcium chloride + amylase treatment method. Therefore, this treatment method was determined to be the best method, and further optimization of this method will be carried out.

[0067] Example 2: Performance Optimization of Modified Reed Adsorbent for Malachite Green Adsorption

[0068] Based on the optimal treatment method determined in Example 1, which was calcium chloride + amylase treatment, this method was further optimized using single-factor methods. Specifically:

[0069] 1. Adsorption test method

[0070] (1) Preparation of modified reed adsorbent: Take 50g of reed (the reed is taken from the area around the salt lake in the salt lake area of ​​Yuncheng City) and boil it in boiling water for 30min and then take it out; prepare a 0.1mol / L calcium chloride solution, soak the reed in it for 2h, then prepare a 0.4g / L amylase solution, wash the soaked reed, put it in the amylase solution in a water bath for 30min at a temperature of 50℃, after the treatment, raise the water bath to 80℃ and perform enzyme inactivation treatment for 20min, then wash the reed until neutral, dry it in an 80℃ oven, and pulverize it to 100 mesh to obtain the modified reed adsorbent, and store it in a sealed container.

[0071] (2) Adsorption test: Take 50 mL of 10 mg / L malachite green solution, add 0.1 g of modified reed adsorbent, adjust the pH to 7, and adsorb for 1 h at room temperature. Take the supernatant. Adjust the wavelength of the UV-Vis spectrophotometer to 619 nm and measure the absorbance.

[0072] 2. Single-factor experiments to optimize adsorption performance

[0073] a. Effect of the particle size of modified reed adsorbent on adsorption

[0074] Under the premise of the adsorption test method, the modified reed adsorbent was pulverized to pass through 20, 40, 60, 80 and 100 mesh sieves, and tests were carried out on each pulverized particle size.

[0075] Experimental results: The experimental results are as follows Figure 6 The effect of the mesh size of the modified reed adsorbent on adsorption is shown: as the mesh size of the modified reed adsorbent increases, the removal rate also gradually increases. Different mesh sizes of the modified reed adsorbent showed highly significant differences in malachite green adsorption at the 1% level (F = 1431.363, P = 0.0001 < 0.01). This phenomenon may be due to smaller particles having a larger specific surface area, providing more adsorption sites for contact with malachite green, thus improving the removal rate. The particle refinement process may also disrupt some structures on the reed surface, exposing more of its internal active groups, enhancing the surface activity of the reed, which is beneficial for the adsorption of malachite green and improving the removal effect. When sieved through a 100-mesh screen, the removal rate reached its maximum of 71.6%.

[0076] b. Effect of modified reed adsorbent dosage on adsorption

[0077] Under the premise of the adsorption test method, the amount of modified reed adsorbent added was set to 0.1g, 0.2g, 0.3g, 0.4g and 0.5g, and tests were conducted on each amount.

[0078] Experimental results: such as Figure 7The effect of modified reed adsorbent dosage on adsorption is shown: with increasing dosage, the removal rate of malachite green by reed first increases and then decreases. The removal rate of malachite green by modified reed adsorbent with a dosage of 0.2 g is significantly better than other dosages at the 1% level (F = 195.037, P = 0.0001 < 0.01). With increasing reed dosage, the number of adsorption sites on its surface and inside increases, allowing it to bind with more malachite green molecules, thus improving the removal rate. However, excessive reeds may stack together, obscuring some adsorption sites and reducing the removal rate. The removal rate reaches its maximum of 78.8% when the dosage is 0.2 g.

[0079] c. Effect of initial concentration of malachite green solution on adsorption

[0080] Under the premise of the adsorption test method, the concentration of malachite green solution was set to 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L and 50 mg / L, and the tests were carried out at 25℃ (room temperature), 35℃ and 45℃ respectively.

[0081] Experimental results: such as Figure 8 The effect of the initial concentration of malachite green solution on adsorption is shown: at different temperatures, with the increase of the initial concentration of malachite green, the removal rate of malachite green solution by the optimized reed showed a decreasing trend, while the adsorption capacity showed an increasing trend. The modified reed adsorbent showed a significantly better removal rate at the 1% level than other concentrations when the malachite green solution concentration was 10 mg / L (Fconcentration = 331.978, P = 0.0001 < 0.01; Ftemperature = 1413.631, P = 0.0001 < 0.01; Fconcentration × temperature = 4.865, P = 0.0006 < 0.01). This phenomenon may be due to the limited number of adsorption sites on reeds. When the malachite green concentration is low, there are sufficient adsorption sites, which can effectively adsorb malachite green and achieve a high removal rate. However, as the concentration increases, the adsorption sites are gradually occupied until saturation, and excess malachite green cannot be adsorbed, leading to a decrease in the removal rate. Alternatively, an increase in the malachite green concentration may increase the competition between molecules, thus affecting the overall removal rate. The removal rate of malachite green reached its maximum when the initial concentration was 10 mg / L.

[0082] d. Effect of adsorption time on adsorption

[0083] Under the premise of the adsorption test method, the adsorption time was set to 20 min, 40 min, 60 min, 80 min and 100 min respectively, and the adsorption time was tested at 25℃ (room temperature), 35℃ and 45℃ respectively.

[0084] Experimental results: such as Figure 9The effect of adsorption time on adsorption is shown: at all temperatures, the removal rate gradually increases with increasing adsorption time. Different times, different temperatures, and the time-temperature interaction all showed highly significant differences at the 1% level (Ftime = 820.242, P = 0.0001 < 0.01; Ftemperature = 1287.621, P = 0.0001 < 0.01; Ftime × temperature = 43.713, P = 0.0001 < 0.01). This phenomenon may be because adsorption is a dynamic process. As time progresses, malachite green molecules have more time to contact and bind with the adsorption sites on the reed surface, thereby continuously increasing the adsorption amount and improving the removal rate. With increasing time, malachite green molecules diffuse more fully into the reed surface and interior in the solution, reaching more adsorption sites and reaction sites, promoting the removal process and increasing the removal rate. The removal rate reaches its maximum at 100 min.

[0085] e. The effect of adsorption temperature on adsorption

[0086] Under the premise of the adsorption test method, the adsorption temperature was set to 20℃, 30℃, 40℃, 50℃ and 60℃ respectively, and the test was carried out at each adsorption temperature.

[0087] Experimental results: such as Figure 10 The effect of adsorption temperature on adsorption is shown: as temperature increases, the removal rate of malachite green by reeds first increases and then decreases (F = 127.777, P = 0.0001 < 0.01). This phenomenon may be due to the fact that appropriately increasing the temperature intensifies molecular thermal motion, while excessively high temperatures may damage the cell structure of reeds, leading to a decrease in the removal rate. The removal rate reaches its maximum of 83.7% at 50℃.

[0088] f. Effect of pH on adsorption

[0089] Under the premise of the adsorption test method, the pH was set to 4, 5, 6, 7, 8, 9, and 10 respectively, and the test was carried out at each pH.

[0090] Experimental results: such as Figure 11 The effect of pH on adsorption is shown: as pH increases, the removal rate of malachite green by reeds first increases and then decreases. At pH 9, the optimized adsorption of malachite green by reeds at the 1% level is significantly better than at other pH values ​​(F = 514.059, P = 0.0001 < 0.01). This phenomenon may be due to changes in the surface charge of the reeds as pH increases, potentially leading to an increase in negative surface charge. Malachite green is a cationic dye with a positive charge; according to the principle of electrostatic attraction, the adsorption effect is enhanced, thus improving the removal rate. However, excessively high pH may cause hydrolysis or denaturation of some organic components in the reeds, affecting adsorption performance. The removal rate reaches its maximum of 81.2% at pH 9.

[0091] 3. Quadratic Regression Orthogonal Rotational Combination Design

[0092] Based on the data obtained from the above experiments, the initial concentration of malachite green solution (X1), adsorption time (X2), and amount of reed added (X3) are the three key factors affecting the reed removal rate.

[0093] Based on the experimental data, the optimal adsorption conditions for each environmental factor were analyzed and set as zero level. A three-factor, five-level coding table was compiled, as shown in Table 2.

[0094] Table 2 Three-Factor Five-Level Coding Table

[0095]

[0096] A quadratic orthogonal rotational combination design was performed using DPS software to obtain an orthogonal rotational combination design table. Based on the data in the rotational combination design table, 23 sets of experiments were conducted. The supernatant was collected, the absorbance was measured, and the removal rate was calculated. The experimental results are shown in Table 3.

[0097] Table 3. Three-factor quadratic regression orthogonal rotational combination design.

[0098]

[0099] The experiment was conducted according to Table 3, the results were calculated, and the following analysis was performed.

[0100] a. The first-order ANOVA table is known as follows: X1 is the initial concentration, X2 is the adsorption time, X3 is the amount added, and Y is the removal rate.

[0101] Table 4. Analysis of First-Order Variance Table

[0102]

[0103] b. Model establishment and testing

[0104] Using DPS to input the results, the regression equation is calculated as follows: Y = 87.06440 + 11.05589X1 + 1.67075X2 - 2.50037X3 - 7.02272X1 2 +0.02714X2 2 +0.44787X3 2 -1.31250X1X2+2.23000X1X3+

[0105] 0.72000X2X3.

[0106] F is obtained through analysis of variance. 失拟 =6.559 < 6.63 indicates that the experimental error is very small, and all unknown factors have been taken into account in the experimental design. F 回归=18.157>4.19, indicating that the regression equation has reached a highly significant level, the experimental inference has high reliability, and the prediction accuracy is high.

[0107] c. Analysis of quadratic variance table

[0108] After removing insignificant factors at the α = 0.10 level, another analysis of variance was performed, as shown in Table 3.4. The regression equation can be simplified to: (α = 0.10) Y = 87.06440 + 11.05589X1 - 2.50037X3 - 7.02272X1 2

[0109] Table 5. Quadratic ANOVA of optimized reed adsorption of malachite green

[0110]

[0111] d. Two-factor interaction effect

[0112] Under optimal conditions for all other factors, X1X3 has the greatest impact on the removal rate among all factor interactions.

[0113] like Figure 12 Interaction analysis of adsorption concentration (X1) and dosage (X3): With X1 constant, the removal rate decreases as X3 increases; with X3 constant, the removal rate first increases and then decreases as X1 increases. The removal rate reaches its highest value of 95.3027% at the level code (1, -1.6818).

[0114] Table 6 shows the impact of X1 and X3 on the removal rate.

[0115]

[0116] e. Optimization analysis and verification

[0117] Using DPS data processing software, when the three factors are at (1, -1.682, -1.682), i.e., the initial concentration of malachite green is 15 mg / L, the adsorption time is 66 min, and the optimized amount of reed is 0.116 g, Y is predicted. max =95.3%. Under the same adsorption conditions, the yield of Y was determined through experimental operation. 实 =93.8%, Y 实 / Y max =0.9843, which is close to 1, indicating that the X1X3 interaction effect has a feasible impact on the adsorption effect.

[0118] Example 3: Study on Adsorption Mechanism

[0119] After determining the optimal addition amount, the applicant also studied the adsorption mechanism of the modified reed adsorbent, comparing the properties of the reed after adsorption under the following conditions: a. original reed, b. modified reed adsorbent prepared by the adsorption experiment method in Example 2-1, and c. reed after adsorption at 50℃, 0.2g reed addition, 100-mesh sieve, pH 9, initial concentration of malachite green solution of 10mg / L, and adsorption time of 100min. The main properties included:

[0120] 1. Scanning electron microscopy (SEM) observation

[0121] Scanning electron microscopy (SEM) is a type of microscope that can observe the microscopic characterization of materials. SEM can provide high-resolution information on the microstructure and elemental distribution of sample surfaces, and is widely used in many fields such as materials science, biology, geology, and semiconductor manufacturing.

[0122] like Figure 13 The image shows a comparison of scanning electron microscope images of three types of reeds. As can be seen from the image, the original reeds have a dense texture, which is not conducive to the adsorption of malachite green. The reeds after modification have a loose texture and more wrinkles. This structure can provide more adsorption sites for the adsorption process. The surface of the reeds after adsorption becomes smooth with fewer pores and wrinkles, which indicates that the loose wrinkles are filled with adsorbate during the adsorption process.

[0123] 2. FTIR (Full-Time Infrared) Analysis

[0124] Infrared spectroscopy was used to analyze the original, optimized, and optimized and adsorbed reeds to determine whether hydroxyl and carboxyl functional groups were present in the adsorption materials.

[0125] like Figure 14 The infrared spectra of three types of reeds are shown. It can be seen that there is a distinct vibrational peak of the hydroxyl-OH functional group around the wavenumber of 3500 cm-1. The transmittance of this absorption peak increases significantly after modification and after adsorption of malachite green solution.

[0126] 3. Elemental analyzer

[0127] An elemental analyzer is an instrument used to determine the composition and content of various elements in a substance. Common types of elemental analyzers are based on chemical analysis principles and physical analysis principles.

[0128] Table 7 shows the elemental analysis of the three types of reeds. It can be seen that the original, optimized, and adsorbed reeds contain multiple elements such as N, C, H, and S. Among them, C is the most abundant, followed by H, then N, and S is the least abundant.

[0129] Table 7. Elemental Analysis of Three Types of Reed

[0130]

[0131] 4. Adsorption isotherm

[0132] The adsorption of malachite green by reeds is a dynamic equilibrium process. At a certain temperature, the adsorption rate changes continuously over time. The most commonly used isothermal models in adsorption equilibrium are the Langmuir isotherm and the Freundlich isotherm.

[0133] Langmuir isotherm: C / q = C / q m +1 / q m b;

[0134] Freundlich's isotherm: q = K·C 1 / n ;

[0135] Linear form: lgq=lgk+(1 / n)lgC;

[0136] Where: C is the equilibrium concentration of malachite green (mg·L⁻¹) -1 ); q is the adsorption capacity (mg·g) -1 );q m Saturated adsorption capacity (mg·g) -1 b is the adsorption equilibrium constant; K is the Freundlich constant; 1 / n is the adsorption index (n is always greater than 1).

[0137] Malachite green solutions of 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L were prepared respectively. Then, 50 mL of each of the above five solutions and 0.1 g of modified reed adsorbent were added to five beakers respectively. Adsorption was carried out at room temperature for 1 h. The supernatant was collected, and the absorbance value was measured and fitted with the adsorption isotherm curve.

[0138] Get as Figure 15 The isotherm graph shown will Figure 15 The data were fitted with the Langmuir and Freundlich adsorption isotherm equations to obtain... Figure 16 The Langmuir model, where the equation at 25°C is: y = 0.0353x + 0.6409, R 2 =0.973; the equation at 35℃ is: y = 0.0354x + 0.3032, R 2 =0.9894; the equation at 45℃ is: y = 0.0319x + 0.2671, R 2 =0.9755), 17Freundlich (Flanderich model, where the equation at 25℃ is: y=0.7228x+0.2642, R 2=0.9885; the equation at 35℃ is: y = 0.633x + 0.545, R 2 =0.9898; the equation at 45℃ is: y = 0.6649x + 0.5665, R 2 =0.9905) and the isothermal parameters of malachite green adsorption by the modified reed adsorbent shown in Table 8 indicate that the adsorption process is more inclined to the Freundlich model, which means that the adsorption process is more inclined to adsorption at heterogeneous sites in a multilayer molecular layer.

[0139] Table 8. Isothermal parameters of malachite green adsorption by modified reed adsorbent.

[0140]

[0141] 5. Adsorption kinetics

[0142] The adsorption kinetics study mainly explores the relationship between the adsorption rate of malachite green by reeds and time under the same initial solution concentration and different adsorption times.

[0143] The pseudo-first-order rate equation is: lg(q) e -q t )=lgq e -k1t / 2.303;

[0144] Quasi-second-order rate equation: t / q t =1 / (k2q) e 2 )+t / q e ;

[0145] Where: q e To balance the adsorption capacity (mg·g) -1 );q t The amount of dye adsorbed at adsorption time t (mg·L) -1 k1 is the pseudo-first-order adsorption rate constant (min). -1 k2 is the pseudo-second-order adsorption rate constant (g·mg). -1 ·min -1 ); t is the adsorption time (min).

[0146] Add 50 mL of 10 mg / L malachite green solution and 0.1 g of modified reed adsorbent to five small beakers, and allow adsorption to proceed at room temperature for 20 min, 40 min, 60 min, 80 min, and 100 min, respectively. Collect the supernatant, calculate the results, and fit them to the adsorption kinetic curve.

[0147] Get as Figure 18The adsorption kinetic curve of malachite green by the modified reed adsorbent is shown. The adsorption capacity of malachite green by reed increases with time, indicating that the modified reed adsorbent has a good removal rate of malachite green. First-order rate equations and pseudo-second-order rate equations were used to analyze the adsorption kinetics of malachite green. Figure 18 The quasi-sum is performed as shown, resulting in the following: Figure 19 (The pseudo-first-order rate equation curve, where the equation at 25℃ is: y = -0.0076x + 0.0907, R) 2 =0.9325; the equation at 35℃ is: y = -0.0106x + 0.2913, R 2 =0.9388; the equation at 45℃ is: y = -0.0151x + 0.0039, R 2 =0.9442) and Figure 20 (The pseudo-second-order rate equation curve, where the equation at 25℃ is: y = 0.2415x + 2.1548, R) 2 =0.9894; the equation at 35℃ is: y = 0.2186x + 2.5736, R 2 =0.9894; the equation at 45℃ is: y = 0.2257x + 0.892, R 2 =0.9998), and the fitting parameters shown in Table 9, it can be seen that the adsorption process of malachite green by the modified reed adsorbent is more in line with the pseudo-second-order adsorption kinetic curve, that is, the process is a physicochemical mixed adsorption process with chemical adsorption as the main component.

[0148] Table 9 Fitting parameters

[0149]

[0150] 6. Adsorption Thermodynamics

[0151] The adsorption thermodynamic parameters are mainly explored to fit thermodynamic parameters under the condition of the same initial concentration of solution at different temperatures.

[0152] The thermodynamic calculation formula is as follows:

[0153] 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, in K; ΔH0 is the enthalpy change of the reaction, in kJ / mol; ΔS0 is the entropy change, in J / (mol·K); and Kc is the thermodynamic equilibrium constant.

[0154] Five small beakers were filled with 50 mL of a 10 mg / L malachite green solution and 0.1 g of modified reed adsorbent, respectively. Adsorption was carried out at room temperature for 20, 40, 60, 80, and 100 min. The supernatant was collected, and the absorbance was measured. The results were calculated and fitted to the adsorption kinetic curve to obtain the following results: Figure 21 (The effect of different temperatures on the adsorption of malachite green by modified reed adsorbent) and Figure 22 From the thermodynamic curves of malachite green adsorption by modified reed adsorbent and Table 10 (thermodynamic parameters of malachite green adsorption by modified reed adsorbent), it can be seen that ΔH0>0 and ΔG0<0, indicating that the adsorption is a spontaneous endothermic reaction; from Figure 22 It can be seen that optimizing the correlation coefficient R of reed adsorption of malachite green... 2 The value is 0.9367, which is close to 1 and conforms to the laws of the thermodynamic model.

[0155] Table 10 Thermodynamic parameters of modified reed adsorbent for adsorbing malachite green

[0156]

[0157] 7. Horizontal comparison

[0158] A comparison of the adsorption effects of common adsorbents such as diatomaceous earth, activated carbon, D101 resin, and bamboo charcoal, as well as modified reed adsorbents and untreated reeds, on malachite green.

[0159] 50 mL of malachite green solutions with concentrations of 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L were added to six beakers, respectively. Then, 0.1 g of optimized reed, untreated reed, diatomaceous earth, D101 macroporous adsorption resin, activated carbon, and bamboo charcoal were added, respectively. After adsorption at room temperature for 1 hour, the supernatant was taken to measure the absorbance value, and the removal rate was calculated.

[0160] The specifications for the six materials are shown in Table 11.

[0161] Table 11 Material Specifications

[0162]

[0163] Experimental results are as follows Figure 23(Comparison of adsorption rates of different materials for malachite green) It can be seen that under the same conditions, the removal rates of various adsorbents for malachite green solution are: modified reed adsorbent > activated carbon > D101 resin > bamboo charcoal > diatomaceous earth > original reed. Next, an analysis of variance was performed on the above data (Table 12) to obtain the effect of different materials on the adsorption of malachite green (Table 13). It can be seen that different materials and different concentrations showed extremely significant differences at the 1% level (F material = 2600.314, P = 0.0001 < 0.01; F concentration = 364.848, P = 0.0001 < 0.01; F material × concentration = 2.755, P = 0.0013 < 0.01). The modified reed adsorbent was significantly better than other materials at the 1% level for adsorbing malachite green solution, that is, modified reed adsorbent > activated carbon > D101 resin > bamboo charcoal > diatomaceous earth > raw reed, indicating that the untreated reed has a low ability to remove pollutants.

[0164] Table 12 Analysis of Variance Table (Duncan's Method)

[0165]

[0166] Table 13. Effects of different materials on malachite green adsorption (Duncan method)

[0167]

[0168] 8. Desorption and regeneration experiment

[0169] a. Adsorption: Reeds treated with the optimal method adsorb malachite green solution under optimal conditions;

[0170] b. Desorption: Prepare a 0.1 mol / L HCl solution and soak the modified reed adsorbent in the HCl for 4 hours. In this way, the malachite green solution adsorbed on the reed can be effectively released and its original physical state can be restored.

[0171] c. Rinsing and Drying: To further clean and ensure the reeds are dry, they need to be rinsed with distilled water. The amount of distilled water should be gradually increased during rinsing until the solution is neutral or slightly alkaline. Afterwards, use a drying device to thoroughly dry the reeds to prevent recontamination that may result from residual moisture.

[0172] The above process was repeated multiple times to determine the adsorption effect and reuse rate of reeds.

[0173] Figure 24 The graph shows the desorption and regeneration of the modified reed adsorbent. As can be seen, even after three adsorption cycles followed by desorption, the removal rate of malachite green remains >70%. The adsorption capacity for malachite green is still present after the eighth desorption cycle.

[0174] (F = 871.801, P = 0.0001 < 0.01) It has a good reuse rate.

[0175] In summary, the modified reed adsorbent obtained by calcium oxide combined with amylase treatment in this application exhibits excellent adsorption performance when applied to the adsorption of malachite green. Specifically, for adsorption solutions with malachite green concentrations around 10 mg / L, by adjusting the particle size, adsorption temperature, dosage, pH, and adsorption time of the modified reed adsorbent, an adsorption rate exceeding 90% can be achieved. Furthermore, its desorption and regeneration capabilities are also excellent, maintaining an adsorption capacity of over 70% even after three desorption and regeneration cycles.

[0176] All technical solutions falling within the scope of this invention are protected. It should be noted that improvements and modifications made by those skilled in the art without departing from the principles of this invention should also be considered within the scope of protection.

Claims

1. A method for preparing a modified reed adsorbent, characterized in that, The process involves first soaking boiled reeds in a calcium chloride solution, then removing and washing them, followed by water bath treatment in an amylase solution, and finally removing them, washing them until neutral, and drying them.

2. The preparation method according to claim 1, characterized in that, The concentration of the calcium chloride solution is 0.1 mol / L, and the concentration of the amylase solution is 0.3 g / L to 0.5 g / L.

3. The preparation method according to claim 1, characterized in that, The water bath temperature for the amylase solution in the water bath treatment is 40-60℃.

4. The modified reed adsorbent prepared by any one of the preparation methods according to claims 1-3.

5. The application of the modified reed adsorbent according to claim 4 in the adsorption of malachite green, characterized in that, The process includes the following steps: crushing the reed adsorbent and placing it in the solution containing malachite green to be adsorbed, adjusting the pH of the solution, and then performing adsorption.

6. The application according to claim 5, characterized in that, The modified reed adsorbent is pulverized to a particle size of 80-100 mesh.

7. The application according to claim 5, characterized in that, The adsorption temperature is 20-50℃.

8. The application according to claim 5, characterized in that, The modified reed adsorbent is added at a rate of 0.2-0.8 g / 100 mL.

9. The application according to claim 5, characterized in that, The pH is adjusted to 8-10.

10. The application according to claim 5, characterized in that, The adsorption time is ≥60 min.

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