Ramie stalk biomass charcoal for adsorbing phthalate compounds as well as preparation method and application of ramie stalk biomass charcoal
By modifying the ramie stalks with alkaline liquid and CaCl2 solution, ramie stalk biomass charcoal with efficient adsorption of PAEs was prepared, which solved the problem of PAEs pollution repair in soil, achieved resource utilization and significantly improved adsorption performance.
Patent Information
- Application Number
- CN202411360515.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-02-11
AI Technical Summary
The prior art is difficult to effectively repair phthalate (PAEs) pollution in soil, and traditional repair methods have problems such as large engineering volume, high environmental risks or long repair cycles.
Ramie stalk biomass charcoal was used as adsorbent, and through the modification of alkali solution and CaCl2 solution, ramie stalk biomass charcoal with rich surface microporous structure and high specific surface area was prepared for adsorption of PAEs in soil.
Effectively reduce residual PAEs in the soil, reduce the risk of PAEs leaching into the groundwater and food chain, realize the utilization of ramie stalk resources, and significantly enhance the adsorption capacity of soil to PAEs.
Smart Images
Figure CN119406371A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of adsorption treatment of phthalate compounds, and in particular to ramie stalk biomass charcoal for adsorbing phthalate compounds, and a preparation method and application thereof. Background Art
[0002] Phthalates (PAEs), also known as phthalic acid esters, are a class of synthetic organic compounds that are widely used in plastic products such as daily necessities, food packaging, interior decoration, and agricultural plastic films to enhance the strength and plasticity of materials. Soil is the main carrier of PAEs. PAEs pollution not only poses a serious threat to the soil environment, but more seriously, PAEs can enter the human body through the food chain, causing serious impacts on human health. Therefore, it is of great significance to study low-cost, green, environmentally friendly, circular and sustainable remediation technologies for soil PAEs pollution remediation.
[0003] At present, the remediation technologies for phthalate-contaminated soil mainly include physical remediation technology, chemical remediation technology and biodegradation remediation technology. Physical remediation technology has the disadvantages of large engineering workload and high remediation cost; chemical remediation technology is prone to secondary pollution to the environment and has long-term potential environmental risks, which requires further supervision; although biodegradation remediation technology is relatively mature and has low remediation costs, the remediation cycle is too long, and each pollutant requires specific microorganisms to be degraded.
[0004] In recent years, the use of biochar made from agricultural and forestry waste to adsorb organic pollutants in soil has attracted widespread attention in the industry. Agricultural and forestry waste such as shell materials (rice husks, peanut shells, walnut shells, etc.), bark materials (wood chips, mango bark, sycamore bark, etc.), peel materials (citrus peel, grapefruit peel, passion fruit peel, etc.) and straw materials (soybean straw, corn straw, wheat straw, etc.) have achieved good adsorption effects.
[0005] Ramie is a perennial herbaceous fiber plant of the genus Ramie in the Urticaceae family. The skin of ramie stalks can be processed to make ramie fiber for ramie textiles. However, the ramie stalks after peeling off the skin are usually regarded as agricultural waste and thrown away at will. It is of great practical significance and environmental value to recycle the discarded ramie stalks and turn waste into treasure.
[0006] Ramie stalks have the characteristics of low ash content and high carbon content. They also contain a large amount of high-quality porous fibers, which can be made into biochar with excellent performance, providing a new way to realize the large-scale resource utilization of ramie waste. At present, a few literatures have reported the preparation methods of ramie stalk biochar and its application methods for adsorbing typical heavy metal ions and phosphate pollutants in wastewater. However, the relevant technology of using ramie stalks as raw materials to prepare high-performance ramie stalk biochar for adsorbing PAEs has rarely been reported. Summary of the invention
[0007] As a widely used and representative PAEs in farmland soil, dibutyl phthalate (DBP) can enter the soil through leaching, migration and other means and be adsorbed by soil particles. The present invention provides a ramie stalk biochar for adsorbing phthalate compounds and a preparation method and application thereof. The prepared ramie stalk biochar can effectively reduce the residual PAEs in the soil, thereby reducing the risk of PAEs leaching into groundwater and entering the food chain, and realizing the resource utilization of ramie stalks. The above-mentioned beneficial effects of the present invention are specifically achieved through the following technologies.
[0008] The present invention provides a method for preparing ramie stalk biomass charcoal, wherein the ramie stalk biomass charcoal is used for adsorbing phthalate compounds; the method for preparing ramie stalk biomass charcoal comprises the following steps:
[0009] Add ramie stalk particles to an alkali solution, stir ultrasonically, let stand, filter, take out the filter residue and dry it to obtain primary ramie stalk particles;
[0010] The primary ramie stalk particles are added to a CaCl2 solution for soaking treatment to remove water, thereby obtaining secondary ramie stalk particles;
[0011] The secondary ramie stalk particles are carbonized in a nitrogen atmosphere, and the product is washed and dried to obtain the ramie stalk biomass charcoal.
[0012] Furthermore, in the method for preparing the ramie stalk biochar provided by the present invention, the mass ratio of the ramie stalk particles, the alkali solution solute and the water is 1:(1-3):25.
[0013] Furthermore, the mass ratio of the ramie stalk particles, the alkali solution solute and the water is 1:2:25.
[0014] Furthermore, in the method for preparing the ramie stalk biomass charcoal provided by the present invention, ramie stalk particles are added to an alkaline solution, ultrasonically stirred for 30-60 min, and allowed to stand for 4-6 h.
[0015] Furthermore, ramie stalk particles were added to the alkaline solution, ultrasonically stirred for 40 min, and allowed to stand for 5 h.
[0016] Furthermore, in the preparation method of the ramie stalk biochar provided by the present invention, the mass fraction of CaCl2 in the CaCl2 solution is 40-80%, the primary ramie stalk particles are added to the CaCl2 solution and soaked for 12-24 h, and the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:(1-3).
[0017] Furthermore, in the method for preparing the ramie stalk biochar provided by the present invention, the primary ramie stalk particles are added to a CaCl2 solution and soaked for 12 hours, and the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:1.
[0018] Furthermore, in the method for preparing the ramie stalk biomass charcoal provided by the present invention, the temperature of the carbonization treatment is 600-800° C., and the treatment time is 1.5 h.
[0019] In the preparation method provided by the present invention, the ramie stalk particles are prepared by crushing the ramie stalks after necessary pretreatment. The necessary pretreatment generally includes cleaning, washing, impurity removal, air drying and other processing processes of the ramie stalks.
[0020] Optionally, the crushing method is to first chop the ramie stalks into pieces of about 2-3 cm, and then crush and sieve them to obtain ramie stalk particles.
[0021] Optionally, the alkali solution used can be a common alkaline solution such as NaOH, KOH, Na2CO3, etc.
[0022] The present invention also provides ramie stalk biomass charcoal for adsorbing phthalate compounds, which is prepared by any of the above preparation methods.
[0023] The ramie stalk biochar provided by the present invention is subjected to two modification treatments. That is, ramie stalk particles are first treated with alkaline solution, so that the acidic substances in the particles can be neutralized and the alkaline active sites on the surface can be significantly increased; the alkaline solid substances remaining inside the ramie stalk particles undergo a dehydration reaction during the pyrolysis treatment, so that the pyrolysis products form a more developed microporous structure. Then, a CaCl2 solution is used for impregnation treatment, which can catalyze the decomposition of volatile components in the ramie stalk biochar, thereby increasing the specific surface area, pore volume and pore size of the biochar. In addition, calcium ions can also catalyze the gasification reaction during the pyrolysis of biochar, accelerate the generation rate of hydroxyl groups in the biochar, and thereby increase the hydroxyl density on the surface of the biochar. The present invention adopts the above two modification treatments when preparing ramie stalk biochar, which exerts a synergistic effect, and the obtained ramie stalk biochar has more abundant oxygen-containing functional groups and a denser aromatic ring structure, and thus has stronger adsorption performance.
[0024] The present invention also provides an application of the ramie stalk biomass charcoal in adsorbing phthalate compounds, wherein the ramie stalk biomass charcoal is mixed with soil to be treated, and water is added for stirring.
[0025] The mass ratio of ramie stalk biochar to the soil to be treated is determined by the content of phthalate compounds in the soil to be treated.
[0026] Generally, the amount (mass) of ramie stalk biochar added is 0.5-1% of the mass of the soil to be treated.
[0027] Compared with the prior art, the advantages of the present invention are as follows: the present invention provides a ramie stalk biochar specifically used for adsorbing phthalates. Compared with the existing biomass charcoal (activated carbon), the ramie stalk biochar prepared by the method of the present invention has a richer surface microporous structure, a higher specific surface area, and has better adsorption performance for phthalate compounds. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a scanning electron microscope image of the ramie stalk biochar prepared at an activation temperature of 700°C in Example 1.
[0029] Figure 2 This is the infrared spectrum of the ramie stalk biochar prepared at an activation temperature of 700°C in Example 1.
[0030] Figure 3 This is the adsorption curve of DBP in soil after adding the ramie stalk biochar prepared in Example 1.
[0031] Figure 4 The Freundlich adsorption coefficient K of the carbon-soil mixture after adding the ramie stalk biochar prepared in Example 1 is f Calculate the result.
[0032] Figure 5 This is a scanning electron microscope image of the ramie stalk biochar prepared in Comparative Example 3.
[0033] Figure 6 This is the infrared spectrum of the ramie stalk biochar prepared in Comparative Example 3. DETAILED DESCRIPTION
[0034] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0035] In some implementation cases of the present invention, the method for preparing ramie stalk biochar is provided as follows:
[0036] Add ramie stalk particles to alkali solution, stir ultrasonically, let stand, filter, take filter residue and dry to obtain primary ramie stalk particles;
[0037] The primary ramie stalk particles are added to a CaCl2 solution for soaking treatment to remove water, thereby obtaining secondary ramie stalk particles;
[0038] The secondary ramie stalk particles are carbonized in a nitrogen atmosphere, and the product is washed and dried to obtain ramie stalk biomass charcoal.
[0039] In some implementation cases of the present invention, the mass ratio of ramie stalk particles, alkali solution solute and water is 1:(1-3):25.
[0040] In some implementation cases of the present invention, after adding the ramie stalk particles to the alkali solution, ultrasonic stirring is performed for 30-60 min and the solution is allowed to stand for 4-6 h.
[0041] In some implementation cases of the present invention, the mass fraction of CaCl2 in the CaCl2 solution is 40-80%, the primary ramie stalk particles are added to the CaCl2 solution and soaked for 12-24 h, and the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:(1-3).
[0042] In some implementation cases of the present invention, the temperature of the carbonization treatment is 600-800° C., and the treatment time is 1.5 h.
[0043] In some implementation cases of the present invention, the alkali solution can be a common alkaline solution such as NaOH, KOH, Na2CO3, etc.
[0044] Specifically, the alkali solution is prepared by adding water to solids such as KOH, NaOH, and Na2CO3.
[0045] In the following examples and comparative examples of the present invention, ramie stalks were obtained from Xiangyang Lake Ramie Experimental Base of Xianning Academy of Agricultural Sciences in Hubei Province. The variety used in the base was Huazhu No. 4 cultivated and produced by the Hemp Research Laboratory of Huazhong Agricultural University.
[0046] Example 1
[0047] The ramie stalk biomass charcoal provided in this embodiment is prepared by the following steps:
[0048] S1. Collect the discarded ramie stalks in the ramie test base, remove the ramie leaves, peel off the ramie skin on the surface, and only keep the above-ground stem part. Wash the ramie stalks with distilled water, remove impurities, and air-dry naturally. Chop the air-dried ramie stalks into 2-3 cm, place them in a grinder, and grind them through a 100-mesh sieve to obtain ramie stalk particles.
[0049] S2. Mix the ramie stalk particles with the KOH solution and stir them evenly. According to the mass ratio, the amount of ramie stalk particles, KOH and water is 1:2:25. After ultrasonic treatment (frequency 40 kHz, power 600 W) for 40 min, place it in a cool place and let it stand for 5 h. Then place it in an oven at 80℃ and dry it for 24 h to obtain primary ramie stalk particles.
[0050] S3. Place the primary ramie stalk particles in a CaCl2 solution with a concentration (mass fraction) of 60% and immerse them for 12 hours. The immersion ratio is 1:1 (i.e., the mass ratio of the primary ramie stalk particles and the CaCl2 solution). Then place the above mixture in an oven (105±5℃) to completely evaporate the water. After cooling to room temperature, secondary ramie stalk particles are obtained.
[0051] S4. Open the tubular furnace and introduce nitrogen into the furnace chamber for 20 min, maintaining a nitrogen flow rate of 40 mL / min to exhaust the air in the furnace as quickly as possible and create a nitrogen reaction environment.
[0052] The secondary ramie stalk particles were placed in a tubular furnace for high-temperature activation treatment at a heating rate of 10 °C / min. After reaching the set temperature of 700 °C, they were kept warm for 1.5 h and then cooled to room temperature before being taken out.
[0053] The product was washed with 70°C distilled water until the pH value was 6.5-7.0, and dried in an oven at 60°C to obtain a ramie stalk biomass charcoal product.
[0054] Example 2
[0055] The preparation method of the ramie stalk biochar provided in this embodiment is basically the same as that in Embodiment 1, except that the mass ratio of ramie stalk particles, KOH solid and water is 1:1:25.
[0056] Example 3
[0057] The preparation method of the ramie stalk biochar provided in this embodiment is basically the same as that in Embodiment 1, except that the mass ratio of ramie stalk particles, KOH solid and water is 1:3:25.
[0058] Example 4
[0059] The preparation method of the ramie stalk biochar provided in this embodiment is basically the same as that in Embodiment 1, except that the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:2.
[0060] Example 5
[0061] The preparation method of the ramie stalk biochar provided in this embodiment is basically the same as that in Embodiment 1, except that the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:3.
[0062] Comparative Example 1
[0063] The ramie stalk biomass charcoal provided in this comparative example is prepared in a method different from that in Example 1 in that no treatment with a CaCl2 solution is used. The ramie stalk biomass charcoal is prepared in the following steps:
[0064] S1. Collect the discarded ramie stalks in the ramie test base, remove the ramie leaves, peel off the ramie skin on the surface, and only keep the above-ground stem part. Wash the ramie stalks with distilled water, remove impurities, and air-dry naturally. Chop the air-dried ramie stalks into 2-3 cm, place them in a grinder, and grind them through a 100-mesh sieve to obtain ramie stalk particles.
[0065] S2. Mix the ramie stalk particles with the KOH solution and stir them evenly. According to the mass ratio, the amount of ramie stalk particles, KOH and water is 1:2:25. After ultrasonic treatment (frequency 40 kHz, power 600 W) for 40 min, place it in a cool place and let it stand for 5 h. Then place it in an oven at 80℃ and dry it for 24 h to obtain primary ramie stalk particles.
[0066] S3. Open the tubular furnace and introduce nitrogen into the furnace chamber for 20 min, maintaining a nitrogen flow rate of 40 mL / min to exhaust the air in the furnace as quickly as possible and create a nitrogen reaction environment.
[0067] The primary ramie stalk particles were placed in a tubular furnace for high-temperature activation treatment at a heating rate of 10 °C / min. After reaching the set temperature of 700 °C, they were kept warm for 1.5 h and then cooled to room temperature and taken out.
[0068] The product was washed with 70°C distilled water until the pH value was 6.5-7.0, and dried in an oven at 60°C to obtain a ramie stalk biomass charcoal product.
[0069] Comparative Example 2
[0070] The ramie stalk biomass charcoal provided in this comparative example is prepared in a method different from that in Example 1 in that KOH solution treatment is not used. The ramie stalk biomass charcoal is prepared by the following steps:
[0071] S1. Collect the discarded ramie stalks in the ramie test base, remove the ramie leaves, peel off the ramie skin on the surface, and only keep the above-ground stem part. Wash the ramie stalks with distilled water, remove impurities, and air-dry naturally. Chop the air-dried ramie stalks into 2-3 cm, place them in a grinder, and grind them through a 100-mesh sieve to obtain ramie stalk particles.
[0072] S2. Place the ramie stalk particles in a CaCl2 solution with a concentration (mass fraction) of 60% and immerse them for 12 hours. The immersion ratio is 1:1 (i.e., the mass ratio of the primary ramie stalk particles and the CaCl2 solution). Then place the above mixture in an oven (105±5℃) to completely evaporate the water. After cooling to room temperature, primary ramie stalk particles are obtained.
[0073] S3. Open the tubular furnace and introduce nitrogen into the furnace chamber for 20 min, maintaining a nitrogen flow rate of 40 mL / min to exhaust the air in the furnace as quickly as possible and create a nitrogen reaction environment.
[0074] The secondary primary ramie stalk particles were placed in a tubular furnace for high-temperature activation treatment at a heating rate of 10 °C / min. After reaching the set temperature of 700 °C, they were kept warm for 1.5 h and then cooled to room temperature and taken out.
[0075] The product was washed with 70°C distilled water until the pH value was 6.5-7.0, and dried in an oven at 60°C to obtain a ramie stalk biomass charcoal product.
[0076] Comparative Example 3
[0077] The preparation method of the ramie stalk biochar provided in this embodiment is different from that in Embodiment 1 in that the CaCl2 solution is replaced by a ZnCl2 solution.
[0078] Test example: Evaluation of the adsorption effect of dibutyl phthalate (DBP) on ramie stalk biochar.
[0079] In this test example, the ramie stalk biochar prepared in the above-mentioned embodiments and comparative examples was used to adsorb and treat simulated soil containing dibutyl phthalate (DBP).
[0080] Weigh biochar and soil in a certain proportion (the mass ratio of biochar to soil is 0.5% and 1%), mix them to prepare the test adsorbent; take 4.0 g of the test adsorbent and place it in a 50 mL polytetrafluoroethylene centrifuge tube.
[0081] Add 20 mL of DBP solution with concentrations of 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 mg / L to a polytetrafluoroethylene centrifuge tube, tighten the stopper, and shake well. Repeat each treatment three times for the six gradient concentrations of the above DBP solution.
[0082] The treated samples were shaken at 180 r / min on a 25°C constant temperature oscillator for 24 h, and then centrifuged at 3000 r / min for 8 min; 1.5 mL of the supernatant was filtered through a 0.45 μm filter membrane.
[0083] The filtrate was taken for gas chromatography-mass spectrometry to determine the DBP content, and the adsorption amount of DBP by soil and biochar was calculated according to the concentration change of the solution before and after adsorption. s (mg / kg).
[0084] Adsorption amount C s The calculation formula is: .
[0085] Where: C s is the adsorption amount of dibutyl phthalate (DBP) on soil and biochar; C e is the concentration of DBP in the liquid phase at adsorption equilibrium (mg / L); K f(L / kg) is the Freundlich adsorption coefficient; 1 / n is the degree of linearity.
[0086] The scanning electron microscope image and infrared spectrum of the ramie stalk biochar prepared in Example 1 are as follows: Figure 1 , 2 After adding the ramie stalk biochar prepared in Example 1, the adsorption curve of soil to DBP is as shown in Figure 3 As shown. It can be seen that the adsorption capacity of soil for DBP is significantly enhanced after adding biochar.
[0087] like Figure 4 As shown in the figure, the Freundlich adsorption coefficient K under the treatment conditions of 1% and 0.5% carbon-soil mass ratio f The values of 3.39 and 1.67 were respectively. This indicates that the soil with 1% biochar added has a stronger adsorption capacity than the soil with 0.5% biochar added.
[0088] The scanning electron microscope image and infrared spectrum of the ramie stalk biochar prepared in Comparative Example 3 are as follows: Figure 5 , 6 shown.
[0089] contrast Figure 1 and Figure 5 It can be seen that the ramie stalk biochar prepared under the experimental conditions of Example 1 (700°C, KOH + CaCl2 treatment) has a more developed surface pore structure, and the pore edges are clearly visible. However, the ramie stalk biochar prepared under the experimental conditions of Comparative Example 3 (700°C, KOH + ZnCl2 treatment) still maintains the basic skeleton of the ramie stalk as a whole, and there are obviously many transparent circular holes on the inner wall of the pores, and the distribution is relatively scattered and irregular.
[0090] Due to the stretching vibration of hydroxyl -OH, the ramie stalk biochar prepared in Comparative Example 3 has a peak at 3375 cm -1 There is an absorption peak near the wave number of 1600 cm-1 due to the stretching vibration of -C=C- and -C=O. -1 The absorption peak appears at 1400 cm due to the symmetric stretching of -COO-. -1 The absorption peak appears at . Figure 2 and 6 The FTIR spectrum analysis results show that the ramie stalk biochar prepared under the experimental conditions of Example 1 (700 °C, KOH + CaCl2 treatment) has a peak at 3375 cm -1 The absorption peak generated near the wave number of has the characteristics of greater intensity and wider peak shape, and the biochar has richer functional groups (-OH, -COO, -C=O, etc.). It can be seen that the introduction of Ca can significantly increase the content of functional groups in biochar.
[0091] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, the technical solution of the present invention can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present invention.
Claims
1. A method for preparing ramie stalk biochar, characterized in that: The ramie stalk biomass charcoal is used to adsorb phthalate compounds; the preparation method of the ramie stalk biomass charcoal comprises the following steps: Add ramie stalk particles to alkali solution, stir ultrasonically, let stand, filter, take filter residue and dry to obtain primary ramie stalk particles; The primary ramie stalk particles are added to a CaCl2 solution for soaking treatment to remove water, thereby obtaining secondary ramie stalk particles; The secondary ramie stalk particles are carbonized in a nitrogen atmosphere, and the product is washed and dried to obtain the ramie stalk biomass charcoal.
2. The method for preparing ramie stalk biochar according to claim 1, characterized in that: The mass ratio of the ramie stalk particles, the alkali solution solute and the water is 1:(1-3):
25.
3. The method for preparing ramie stalk biochar according to claim 2, characterized in that: The mass ratio of the ramie stalk particles, the alkali solution solute and the water is 1:2:
25.
4. The method for preparing ramie stalk biochar according to claim 1, characterized in that: Take ramie stalk particles and add them to the alkaline solution, stir them ultrasonically for 30-60 min, and let them stand for 4-6 h.
5. The method for preparing ramie stalk biochar according to claim 4, characterized in that: Take ramie stalk particles and add them to the alkaline solution, stir them ultrasonically for 40 min, and let them stand for 5 h.
6. The method for preparing ramie stalk biochar according to claim 1, characterized in that: The mass fraction of CaCl2 in the CaCl2 solution is 40-80%, the primary ramie stalk particles are added to the CaCl2 solution and soaked for 12-24 hours, and the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:(1-3).
7. The method for preparing ramie stalk biochar according to claim 6, characterized in that: The primary ramie stalk particles are added to a CaCl2 solution and soaked for 12 hours, and the mass ratio of the primary ramie stalk particles to the CaCl2 solution is 1:
1.
8. The method for preparing ramie stalk biochar according to claim 1, characterized in that: The temperature of the carbonization treatment is 600-800°C and the treatment time is 1.5 h.
9. A ramie stalk biochar for adsorbing phthalate compounds, characterized in that: The method is prepared according to any one of claims 1 to 8.
10. A ramie stalk biochar prepared by the preparation method according to any one of claims 1 to 8, or use of the ramie stalk biochar according to claim 9 in adsorbing phthalate compounds, characterized in that: The ramie stalk biomass charcoal and soil are mixed, and water is added and stirred.