A method for preparing an adsorbent for removing malachite green from wastewater

Abstract

The application discloses a preparation method of an adsorbent for removing malachite green in wastewater, and comprises the following steps: collecting poplar catkins around a campus, removing other sundries, washing and flushing the poplar catkins with tap water, drying the poplar catkins, soaking the poplar catkins in a solution containing 3-chloro-2-hydroxypropane sulfonic acid sodium, and performing ultrasonic treatment to obtain hydrophilic poplar catkins; after the hydrophilic poplar catkins are squeezed dry, the poplar catkins are placed in a mixed solution of boric acid-triethylamine, modified treatment is performed under the action of ultrasonic waves, the poplar catkins are taken out after a period of reaction, are filtered, are washed with a dilute acetic acid solution for several times, are washed with distilled water until the pH is 5-7, and are dried in an oven to obtain fibrous poplar catkin adsorbents, which are used for removing malachite green and other cationic dyes in wastewater; the adsorbent preparation method is simple, has large adsorption capacity, and is a relatively good adsorbent for removing malachite green in wastewater.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to a method for preparing a malachite green adsorbent for removing dyes from wastewater. Background Technology

[0002] Poplar catkins originate from poplar trees, one of the main tree species used in urban greening. Every spring and summer, large amounts of catkins produced by poplar trees along city roads float in the air, gathering like snowflakes. When the wind blows, they cause environmental pollution, inconvenience to people's lives, and can even lead to respiratory infections, skin allergies, sudden fires, and blocked car radiators. Poplar catkins are lightweight and fibrous, containing 0.89% nitrogenous compounds, 1.55% pentosans, 1.14% ash, and 0.66% waxes and fats. They are insoluble in water and have no practical value, often being treated as waste. However, experiments have shown that with certain chemical or physical treatments, poplar catkins can serve as an excellent adsorbent material for treating wastewater from the dye industry. They effectively adsorb cationic dyes such as malachite green, methylene blue, acid red, and crystal violet, reducing dye wastewater emissions from textile, pulp and paper, and leather manufacturing industries. Because raw poplar catkins are lightweight and have poor hydrophilicity, they require modification before they can be used as an adsorbent for wastewater treatment. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a method for preparing a malachite green adsorbent for removing wastewater.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a malachite green adsorbent for removing malachite green from wastewater, comprising the following steps:

[0005] S1. Washing poplar catkins: Collect poplar catkins from the willow groves around the campus, manually remove branches, leaves, pebbles and other debris, then weigh a certain amount of poplar catkins, wash them with tap water, drain the water and set aside for use.

[0006] S2. Pretreatment: The poplar catkins washed in S1 are soaked in a solution containing sodium 3-chloro-2-hydroxypropanesulfonate and pretreated under ultrasonic waves to obtain hydrophilic poplar catkins.

[0007] S3. Preparation of modifier: Dissolve boric acid in distilled water, then add triethylamine solution and stir until homogeneous to obtain a mixed solution of modifier.

[0008] S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the mixed solution prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After reacting for a period of time, take them out and filter them, wash them several times with dilute acetic acid solution, and then wash them several times with distilled water until the pH is 5-7. Squeeze out the water and then place them in an oven to dry, and obtain fibrous poplar catkin adsorbent.

[0009] S5. Adsorption Experiment: Pipette 25 mL of wastewater containing malachite green into a stoppered conical flask, and adsorb it with 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1 Adjust the pH of the NaOH solution to 5–7, bring the volume to 50 mL, add 0.10–0.20 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 1–3 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0–12 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Calculate the adsorption rate of the poplar catkin adsorbent for malachite green in the solution at adsorption equilibrium using the following formula. ƞ ,%).

[0010] Adsorption rate calculation formula:

[0011] ƞ %= [( C 0 -C e ) / C 0 ] • 100% ， in ƞ For adsorption rate, C o represents the initial concentration of the adsorption solution. C e represents the equilibrium concentration after adsorption.

[0012] Furthermore, the mass concentration of the sodium 3-chloro-2-hydroxypropanesulfonate solution in S2 is 10-15%.

[0013] Furthermore, the solid-liquid ratio of the poplar catkins to the sodium 3-chloro-2-hydroxypropanesulfonate solution in S2 is 1:4 to 10.

[0014] Furthermore, the ultrasonic frequency of the ultrasonic treatment described in S2 is 50-90 kHz, and the treatment time is 20-60 min.

[0015] Furthermore, the ratio of boric acid:triethylamine:water in S3 is 3-5:5-10:80-100.

[0016] Furthermore, in S4, the ultrasonic frequency for modification treatment in the ultrasonic cleaner is 60–120 kHz, and the treatment time is 30–60 min.

[0017] Furthermore, the mass concentration of the dilute acetic acid solution in S4 is 3%.

[0018] Furthermore, the drying temperature in the oven described in S4 is 50-80℃, and the drying time is 5-10 h.

[0019] Furthermore, in S5, the concentration of malachite green remaining in the solution after adsorption was determined by preparing a standard curve of 0–8.4 μg / mL malachite green, as follows: Figure 1 As shown, the linear equation is: A = 0.0092C - 0.0073, and the correlation coefficient is... R 2 =0.9997.

[0020] Beneficial Effects: This invention prepares an effective adsorbent by chemically treating poplar fluff or cottonwood seeds under ultrasonic waves. This adsorbent can be widely used to adsorb and remove cationic dyes such as malachite green, methylene blue, methyl red, and crystal violet from wastewater. The adsorbent preparation method of this invention is simple, with large adsorption capacity and high adsorption rate, and it can be mass-produced. It has broad application prospects in wastewater discharged from industries such as textiles, pulp and paper, and leather manufacturing. Attached Figure Description

[0021] Figure 1 The standard curve for determination using malachite green solution in this patent;

[0022] Figure 2 The effect of pH value of the solution on the adsorption rate of malachite green in this patent;

[0023] Figure 3 The effect of adsorption time on the adsorption rate of malachite green in this patent;

[0024] Figure 4 The effect of initial concentration on the adsorption rate of malachite green in this patent;

[0025] Figure 5 The kinetic fitting curve of the poplar catkin adsorbent in this patent;

[0026] Figure 6 The Langmuir isotherm adsorption curve obtained during the adsorption process of this patent. Detailed Implementation Plan

[0027] The structure and working principle of the present invention will be further explained below with reference to the accompanying drawings and specific embodiments:

[0028] A method for preparing a malachite green adsorbent for removing malachite green from wastewater, comprising:

[0029] Poplar catkin cleaning: Collect poplar catkins from the willow groves around the campus. Manually remove branches, leaves, pebbles, and other debris. Then weigh a certain amount of catkins, wash them with tap water, drain the water, and set aside. The catkins falling to the ground will contain some leaves, branches, and pebbles, which are manually picked out to ensure the catkins are not affected by impurities. Washing with water is mainly to remove mud and sand. Squeezing by hand removes most of the water, so drying is not necessary before proceeding to the next step.

[0030] Pretreatment involves soaking the washed poplar catkins in a solution containing sodium 3-chloro-2-hydroxypropanesulfonate and pretreating them under ultrasonic waves to obtain hydrophilic poplar catkins. Since poplar catkins are fibrous materials with poor water compatibility, the use of sodium 3-chloro-2-hydroxypropanesulfonate solution under ultrasonic waves improves the hydrophilicity of the poplar catkin fibers, laying the foundation for further processing.

[0031] Preparation of modifier: Boric acid is dissolved in distilled water, then triethylamine solution is added and stirred evenly to obtain a mixed solution of modifier.

[0032] Modification treatment: Hydrophilic poplar catkins were placed in a mixed solution of boric acid and triethylamine. Triethylamine, a weak organic base, dissolves the waxes and hemicellulose in the poplar catkin fibers, making the fibers hydrophilic without compromising their tensile and breaking strength. Simultaneously, it exposes the functional groups on the surface of the catkins, allowing for better binding with cationic dyes. Under ultrasonic treatment in the boric acid solution, cavitation bubbles impact the fiber surface, creating numerous pits and voids, thus increasing the surface area of ​​the poplar catkin fibers. At the same time, boric acid protects the hydroxyl groups on the fiber surface from damage. In the experiment, the ultrasonically treated poplar catkins were not pulverized in a high-speed pulverizer and retained their fiber structure, indicating that the treated poplar catkin fibers have good toughness. In contrast, the original poplar catkins, after washing and drying, turned into powder upon pulverization. Washing the treated poplar catkins with dilute acetic acid solution effectively removed free boric acid; washing with distilled water to a pH of 5-7 was used to adjust the pH of the solution for adsorption. The treated poplar catkins were dried at low temperature to obtain fibrous poplar catkin adsorbent.

[0033] Adsorption experiment: A certain concentration of malachite green standard solution was pipetted into a 100 mL stoppered conical flask, and 0.10 mol·L⁻¹ adsorption solution was added. -1 HCl and 0.10 mol·L -1Adjust the pH of the NaOH solution to 2–8, bring the volume to 50 mL, add 0.10–0.20 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 1–3 h on a constant-temperature shaker. Then centrifuge using a high-speed centrifuge to obtain the supernatant after adsorption. Measure the absorbance of different supernatants and 0–8.4 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Figure 1 As shown, the malachite green standard solution exhibits excellent linearity in the range of 0–8.4 mg / L, with a correlation coefficient of [missing value]. R 2 =0.9992.

[0034] like Figure 2 As shown, the adsorption rate of malachite green is 95.6%-99.4% within the pH range of 3-7. At pH 7, the adsorption rate is constant. The pH range of 5-6 is selected based on the actual acidity / alkalinity of the dye wastewater. Overall, pH changes significantly affect the adsorption of malachite green by poplar catkins, and poplar catkins themselves exhibit good adsorption performance. At pH 3, the adsorption effect of both untreated natural poplar catkins and the adsorbent prepared according to this invention is poor. The adsorption effect improves as the pH increases. This may be because at lower pH levels, the H+... + A higher concentration of these pollen particles will compete with the cationic dye malachite green for adsorption, resulting in a lower adsorption rate. When pH increases, the hydroxyl groups (-OH) on the surface of the poplar fluff ionize into negatively charged -O groups. - It has a strong adsorption capacity for positively charged dyes.

[0035] Figure 3 The effect of adsorption time (oscillation time) on adsorption rate can be seen. It can be seen that when the oscillation time is between 5 and 60 minutes, the adsorption rate increases with the extension of the oscillation time. At 90 minutes, the adsorption rate of malachite green has reached 99.3%. As the time continues to extend, the adsorption rate no longer increases, indicating that the adsorption equilibrium has been reached and the adsorption capacity of the adsorbent reaches 20.86 mg / g.

[0036] The saturated adsorption capacity of poplar catkin adsorbent for malachite green ( q )for:

[0037]

[0038] In the formula, C 0 represents the initial concentration of the malachite green solution; C e This is the concentration of the malachite green solution when adsorption equilibrium is reached. This data can be calculated from the standard curve of malachite green. V is the initial test volume of the malachite green solution; m is the amount of poplar catkin adsorbent used.

[0039] Figure 4The relationship between initial concentration and malachite green adsorption capacity shows that the adsorption rate remains largely unchanged when the initial concentration ranges from 20 to 116 μg / mL. However, as the initial concentration of malachite green continues to increase, the adsorption rate decreases. This is because, with a fixed mass of adsorbent, as the concentration increases, the adsorption gradually approaches the saturation value, resulting in a small amount of malachite green remaining unadsorbed.

[0040] Adsorption kinetics study: To investigate the adsorption process, quasi-first-order and quasi-second-order kinetic models were used to linearly fit the experimental data. The fitting results are shown in [the table below]. Figure 5 .

[0041] The pseudo-first-order dynamic model is as follows:

[0042]

[0043] The pseudo-second-order dynamic model is as follows:

[0044]

[0045] in: k 1 represents the adsorption reaction rate constant of the pseudo-first-order kinetic model, min -1 ; k 2 represents the adsorption reaction rate constant of the pseudo-second-order kinetic model, in g / (mg·min). q t The amount of dye adsorbed per unit mass of adsorbent at time t, in mg / g; q e The value represents the amount of dye adsorbed per unit mass of adsorbent at adsorption equilibrium, expressed in mg / g. The results are shown in Figure 1.

[0046] Table 1. Kinetic parameters of malachite green adsorption by poplar catkins

[0047]

[0048] As shown in Table 1, both pseudo-first-order and pseudo-second-order reaction kinetic equation models can fit the process of modified poplar fluff adsorbing malachite green, with the pseudo-second-order kinetic model showing a higher degree of fit. R 2 =1). In addition, the equilibrium adsorption capacity obtained by fitting the pseudo-second-order reaction kinetic equation was 20.81 mg / g, which is very close to the experimentally obtained equilibrium adsorption capacity of 20.86 mg / g, indicating that the pseudo-second-order kinetic equation can well reflect the adsorption mechanism of modified poplar catkins on malachite green.

[0049] Adsorption isotherm:

[0050] In this patent, the Langmuir adsorption isotherm model was used to linearly fit the adsorption equilibrium data of 100 mg of poplar fluff adsorbing 70 μg / mL malachite green solution at 25℃. The fitting parameters are shown in Table 2, and the fitting curves are shown in [Table 2]. Figure 6 The Langmuir adsorption isotherm model is as follows:

[0051]

[0052] in: C e represents the concentration of malachite green at adsorption equilibrium, in μg / mL; q e qm represents the amount of dye adsorbed per unit mass of adsorbent at adsorption equilibrium, in mg / g; qm represents the amount of dye adsorbed per unit mass of adsorbent at saturation, in mg / g; and b represents the adsorption rate constant, in L / mg.

[0053] Table 2. Relevant parameters of the Langmuir adsorption isotherm model

[0054]

[0055] As shown in Table 2, the Langmuir isotherm adsorption equation can well fit the adsorption process of malachite green by modified poplar fluff. R 2 =0.9982), indicating good adsorption correlation. The maximum saturated adsorption capacity per unit mass of adsorbent during the adsorption process was 21.14 mg / g.

[0056] Example 1

[0057] S1. Collection and cleaning: Collect poplar catkins from the willow groves around the campus, manually remove branches, leaves, pebbles and other debris, then weigh 10g of poplar catkins, wash them with tap water, drain the water and set aside for use.

[0058] S2. Pretreatment: The poplar catkins washed in S1 are soaked in 100 mL of 10% sodium 3-chloro-2-hydroxypropanesulfonate solution and pretreated under ultrasonic frequency of 50 kHz for 60 min to obtain hydrophilic poplar catkins.

[0059] S3. Preparation of modifier: Dissolve 3g of boric acid in 80g of distilled water, then add 10g of triethylamine solution and stir evenly to obtain a mixed solution of modifier.

[0060] S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the mixed solution prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After treatment at an ultrasonic frequency of 120 kHz and a time of 60 min, take them out and filter them. Wash them three times with a 3% dilute acetic acid solution, and then wash them three times with distilled water until the pH is 5. Squeeze out the water and then dry them in a 50℃ oven for 10 h to obtain fibrous poplar catkin adsorbent.

[0061] S5. Adsorption Experiment: Pipette 25 mL of 0.700 mg / mL malachite green standard solution into a stoppered conical flask, and adsorb 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1 Adjust the pH to 5 with NaOH solution, bring the volume to 50 mL, add 0.10 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 1 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0–12 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the measurement results. ƞ The adsorption rate of malachite green was 99.12%, and the saturation adsorption capacity was 21.03 mg / g.

[0062] Example 2

[0063] S1. Collection and cleaning: Collect poplar catkins from the willow groves around the campus, manually remove branches, leaves, pebbles and other debris, then wash 10g of poplar catkins with tap water, drain the water and set aside for use.

[0064] S2. Pretreatment: The poplar catkins washed in S1 are soaked in 40 mL of 15% sodium 3-chloro-2-hydroxypropanesulfonate solution and pretreated under ultrasonic frequency of 90 kHz for 20 min to obtain hydrophilic poplar catkins.

[0065] S3. Preparation of modifier: Dissolve 5g of boric acid in 100g of distilled water, then add 5g of triethylamine solution and stir evenly to obtain a mixed solution of modifier.

[0066] S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the mixed solution prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After treatment at an ultrasonic frequency of 60 kHz and a time of 30 min, take them out and filter them. Wash them 5 times with a 3% dilute acetic acid solution, and then wash them 5 times with distilled water until the pH is 7. Squeeze out the water and then dry them in an 80℃ oven for 5 h to obtain fibrous poplar catkin adsorbent.

[0067] S5. Adsorption Experiment: Pipette 25 mL of 0.700 mg / mL malachite green standard solution into a stoppered conical flask, and adsorb 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1 Adjust the pH to 6 with NaOH solution, bring the volume to 50 mL, add 0.15 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 3 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0–12 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the measurement results. ƞ The adsorption rate of malachite green was 99.47%, and the saturation adsorption capacity was 21.47 mg / g.

[0068] Example 3

[0069] S1. Collection and cleaning: Collect poplar catkins from the willow groves around the campus, manually remove branches, leaves, pebbles and other debris, then wash 10g of poplar catkins with tap water, drain the water and set aside for use.

[0070] S2. Pretreatment: The poplar catkins washed in S1 are soaked in 60 mL of 13% sodium 3-chloro-2-hydroxypropanesulfonate solution and pretreated under ultrasonic frequency of 70 kHz for 40 min to obtain hydrophilic poplar catkins.

[0071] S3. Preparation of modifier: Dissolve 4g of boric acid in 90g of distilled water, then add 8g of triethylamine solution and stir evenly to obtain a mixed solution of modifier.

[0072] S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the mixed solution prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After treatment at an ultrasonic frequency of 90 kHz and a time of 45 min, take them out and filter them. Wash them 4 times with a 3% dilute acetic acid solution, and then wash them 4 times with distilled water until the pH is 6.4. Squeeze out the water and then dry them in a 60℃ oven for 7 h to obtain fibrous poplar catkin adsorbent.

[0073] S5. Adsorption Experiment: Pipette 25 mL of 0.700 mg / mL malachite green standard solution into a stoppered conical flask, and adsorb 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1Adjust the pH to 5.5 with NaOH solution, bring the volume to 50 mL, add 0.20 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 2.5 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0–12 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the measurement results. ƞ The adsorption rate of malachite green was 99.83%, and the saturation adsorption capacity was 21.62 mg / g.

[0074] Example 4

[0075] S1. Collection and cleaning: Collect poplar catkins from the willow groves around the campus, manually remove branches, leaves, pebbles and other debris, then wash 10g of poplar catkins with tap water, drain the water and set aside for use.

[0076] S2. Pretreatment: The poplar catkins washed in S1 are soaked in 80 mL of 12% sodium 3-chloro-2-hydroxypropanesulfonate solution and pretreated under ultrasonic frequency of 75 kHz for 50 min to obtain hydrophilic poplar catkins.

[0077] S3. Preparation of modifier: Dissolve 5g of boric acid in 100g of distilled water, then add 10g of triethylamine solution and stir evenly to obtain a mixed solution of modifier.

[0078] S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the mixed solution prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After treatment at an ultrasonic frequency of 100 kHz and a time of 50 min, take them out and filter them. Wash them 3 times with a 3% dilute acetic acid solution and then wash them 5 times with distilled water until the pH is 5.8. Squeeze out the water and then dry them in an 80℃ oven for 9 h to obtain fibrous poplar catkin adsorbent.

[0079] S5. Adsorption Experiment: Pipette 25 mL of 0.700 mg / mL malachite green standard solution into a stoppered conical flask, and adsorb 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1 Adjust the pH to 7.0 with NaOH solution, bring the volume to 50 mL, add 0.15 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 3 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0–12 mg / L malachite green standard solutions at the maximum absorption wavelength λ = 615 nm. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the measurement results. ƞ The adsorption rate of malachite green was 98.69%, and the saturation adsorption capacity was 21.49 mg / g.

[0080] Example 5

[0081] Similar to Example 1, except that the malachite green standard solution in step S5 was replaced with a 0.5000 mg / mL methylene blue solution, and the other steps were the same. The adsorption rate of methylene blue was 99.31%, and the saturated adsorption rate of methylene blue was calculated to be 28.2 mg / g according to the Langmuir adsorption formula.

[0082] Example 6

[0083] Similar to Example 2, except that the malachite green standard solution in step S5 was replaced with a 0.5000 mg / mL Congo red solution, and the other steps were the same. The adsorption rate of Congo red was 98.79%, and the saturated adsorption capacity of Congo red was calculated to be 25.56 mg / g according to the Langmiur adsorption formula.

[0084] Example 7

[0085] Similar to Example 3, except that the malachite green standard solution in step S5 was replaced with a 0.5000 mg / mL crystal violet solution, and the other steps were the same. The adsorption rate of crystal violet was 99.06%, and the saturated adsorption rate of crystal violet was 29.48 mg / g according to the Langmuir adsorption formula.

[0086] Comparative Example 1

[0087] Similar to S1 and S5 in Example 1, the poplar catkins were not modified and were directly subjected to adsorption experiments.

[0088] S1. Collect poplar catkins from the willow groves around the campus. After manually removing branches, leaves, pebbles, and other debris, wash with tap water, drain, and dry at 50℃ for 10 hours. Weigh 0.1g for adsorption experiments. Other conditions are the same as in S5. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the measured results. ƞ The adsorption rate of malachite green was 13.15%, which is relatively low; the saturated adsorption capacity was also relatively low at 1.97 mg / g.

[0089] Comparative Example 2

[0090] Similar to S1 and S5 in Example 2, no modification treatment was performed, and the adsorption experiment was carried out directly.

[0091] S1. Collect poplar catkins from the willow groves around the campus. After manually removing branches, leaves, pebbles, and other debris, wash with tap water, drain, and dry at 70℃ for 5 hours. Weigh 0.15g for adsorption experiments. Other conditions are the same as in S5. Calculate the adsorption rate of malachite green in the solution by the poplar catkin adsorbent based on the results. ƞThe adsorption rate of malachite green was 12.678%, which is not high. The saturated adsorption capacity was 2.06 mg / g.

[0092] Application Example 1

[0093] Similar to Example 1, except that malachite green dye wastewater was added in step S5, and the other steps were the same. The pH of the wastewater was adjusted to 5.5 with dilute hydrochloric acid and dilute sodium hydroxide, and then added to the treated poplar fibers to obtain an adsorption rate of 99.52% for malachite green in the wastewater.

[0094] Application Example 2

[0095] Similar to Example 1, except that methylene blue dye wastewater was added in step S5, and the other steps were the same. The pH of the wastewater was adjusted to 6.2 with dilute hydrochloric acid and dilute sodium hydroxide, and then added to the treated poplar fibers to obtain an adsorption rate of 98.39% for malachite green in the wastewater.

[0096] As can be seen from Examples 1-5 and Comparative Examples 1-2 above, the adsorption rate of malachite green by poplar catkins after treatment is significantly increased, and the saturated adsorption capacity can reach more than 21.0 mg / g. The saturated adsorption capacity of raw poplar catkins for malachite green is only about 2.0 mg / g. In addition, this treated poplar catkin adsorbent also has a high adsorption capacity for cationic dyes such as methylene blue, Congo red, and crystal violet, and can be used for the treatment of dye wastewater.

Claims

1. A method for preparing a malachite green adsorbent for removing malachite green from wastewater, characterized in that, Includes the following steps: S1. Collection and washing: Collect poplar catkins from the poplar forest around the campus, manually remove branches, leaves, small stones and other debris, then weigh a certain amount of poplar catkins, wash them with tap water, drain the water and set aside for use. S2. Pretreatment: The poplar catkins washed in S1 are soaked in a solution containing sodium 3-chloro-2-hydroxypropanesulfonate and pretreated under ultrasonic waves to obtain hydrophilic poplar catkins. S3. Preparation of modifier: Dissolve boric acid in distilled water, then add triethylamine solution and stir evenly to obtain a mixed solution of modifier; S4. Modification treatment: Take out the hydrophilic poplar catkins obtained in S2, squeeze out the water, put them into the modifier mixture prepared in S3, and place them in an ultrasonic cleaner for modification treatment. After reacting for a period of time, take them out and filter them, wash them several times with dilute acetic acid solution, and then wash them several times with distilled water until the pH is 5-7. Squeeze out the water and then place them in an oven to dry, to obtain fibrous poplar catkin adsorbent. S5. Adsorption Experiment: Pipette 25 mL of wastewater containing malachite green into a stoppered conical flask, and adsorb it with 0.10 mol·L⁻¹ water. -1 HCl and 0.10 mol·L -1 Adjust the pH of the NaOH solution to 5-7, bring the volume to 50 mL, add 0.10-0.20 g of the prepared poplar catkin adsorbent, and shake at 180 r / min for 1-3 h on a constant temperature shaker. Filter and collect the filtrate. Measure the absorbance of different filtrates and 0-12 mg / L malachite green standard solution at the maximum absorption wavelength λ=615 nm. Calculate the adsorption rate of malachite green in the wastewater by the poplar catkin adsorbent based on the measurement results.

2. The preparation method according to claim 1, characterized in that, The mass concentration of the sodium 3-chloro-2-hydroxypropanesulfonate solution in S2 is 10-15%.

3. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of poplar catkins to sodium 3-chloro-2-hydroxypropanesulfonate solution in S2 is 1:4 to 10 by mass:volume, and the unit of measurement for the solid-liquid ratio is g / mL.

4. The preparation method according to claim 1, characterized in that, The ultrasonic frequency of the ultrasonic treatment in S2 is 50-90 kHz, and the treatment time is 20-60 min.

5. The preparation method according to claim 1, characterized in that, The ratio of boric acid:triethylamine:water in S3 is prepared according to a mass ratio of 3-5:5-10:80-100.

6. The preparation method according to claim 1, characterized in that, In step S4, the ultrasonic frequency for modification treatment in an ultrasonic cleaner is 60–120 kHz, and the treatment time is 30–60 min.

7. The preparation method according to claim 1, characterized in that, The mass concentration of the dilute acetic acid solution in S4 is 3%.

8. The preparation method according to claim 1, characterized in that, In step S4, the drying temperature in the oven is 50–80°C, and the drying time is 5–10 hours.

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