Adsorbing material for treating organic wastewater and preparation method thereof

Abstract

The application provides an adsorption material for organic wastewater treatment and a preparation method thereof, and relates to the technical field of organic wastewater treatment.The preparation method comprises the following steps: preparing straw powder and cyanobacteria powder, high-temperature carbonization, mixing a treatment liquid, heat treatment, cooling and the like.Meanwhile, the composition of the treatment liquid and the heat treatment process are limited.Through adjusting the sources of the biochar raw materials and the proportioning of the biochar raw materials, and combining the optimization of the preparation process, the regeneration performance of the adsorption material is significantly improved, the treatment time is shortened, and the treatment efficiency is improved.The preparation method is simple and easy to implement, is suitable for large-scale industrial production, and has a wide application prospect in the field of organic wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of organic wastewater treatment technology, and in particular to an adsorbent material for organic wastewater treatment and its preparation method. Background Technology

[0002] With the rapid development of the industrial economy, a large amount of organic wastewater is inevitably generated during the production process of various industries. This organic wastewater is rich in various chemical substances, and due to its poor biodegradability and large differences in relative molecular mass, it is very challenging to treat. If this organic wastewater is discharged directly without treatment, it will seriously harm the ecological environment and water quality. In addition, this type of organic wastewater also contains a large number of toxic substances, and traditional biological degradation treatment methods can no longer meet the requirements of relevant treatment standards.

[0003] There are various methods for treating organic wastewater, mainly including physical treatment, chemical treatment, physicochemical treatment, and biological treatment. Physical treatment methods, such as screens, sedimentation tanks, and equalization tanks, are mainly used to remove large particles and suspended solids; chemical treatment methods, such as coagulation and oxidation-reduction, are used to remove some dissolved organic matter; physicochemical treatment methods, such as adsorption (using adsorbents such as activated carbon and molecular sieves) and membrane separation technologies (such as reverse osmosis and nanofiltration), are used to remove small molecule organic matter; biological treatment methods include aerobic treatment (activated sludge process, biofilm process) and anaerobic treatment (UASB, anaerobic filter), utilizing microorganisms to degrade organic matter; advanced oxidation processes, such as Fenton's reagent, ozone oxidation, and ultraviolet photocatalysis, are used for recalcitrant organic matter; evaporation concentration and pyrolysis / incineration are used to concentrate high-concentration wastewater, and the concentrate can be completely treated through pyrolysis or incineration. These methods can be combined according to the specific properties of the wastewater and treatment requirements to achieve the best treatment effect.

[0004] Adsorption is an effective method for treating organic wastewater, offering advantages such as high treatment efficiency, simple operation, small footprint, and no secondary pollution. However, the adsorption method consumes a large amount of adsorbent material, is prone to saturation, requires frequent replacement, increasing operating costs, has a long treatment time, and faces difficulties in adsorbent regeneration. The process is complex and costly, impacting economic viability.

[0005] Therefore, improving the adsorption performance, adsorption efficiency, and regeneration performance of adsorption materials is of great significance for improving the efficiency and economy of organic wastewater treatment, reducing environmental burden, and promoting sustainable development. Summary of the Invention

[0006] In view of this, the present invention provides an adsorbent material for treating organic wastewater and a method for preparing the same. By adjusting the source and proportion of biochar raw materials and modifying the preparation process, the present invention significantly improves the regeneration performance of the adsorbent material, and to a certain extent, shortens the treatment time and improves the treatment efficiency.

[0007] The preparation method of the adsorbent material for organic wastewater treatment according to the present invention includes the following steps:

[0008] S1. Dry and pulverize the straw and cyanobacteria separately, and pass them through an 80-100 mesh sieve to obtain straw powder and cyanobacteria powder;

[0009] S2. Mix straw powder and blue-green algae powder to obtain mixed powder, add sodium hydroxide and carbonize at high temperature under argon atmosphere to obtain biochar;

[0010] S3. The biochar is mixed with the treatment liquid, heat-treated, and cooled to obtain an adsorbent material for organic wastewater treatment.

[0011] Furthermore, the drying temperature is 100℃~120℃, and the drying time is 8~12h.

[0012] Further, the mass ratio of the straw powder to the cyanobacteria powder is (3-5):1. Preferably, the mass ratio of the straw powder to the cyanobacteria powder is 4:1.

[0013] Further, the mass ratio of sodium hydroxide to the mixed powder is (1-2):1. Preferably, the mass ratio of sodium hydroxide to the mixed powder is 1.5:1.

[0014] Further, the carbonization temperature is 800℃~900℃, and the carbonization time is 2~3h. Preferably, the carbonization temperature is 850℃, and the carbonization time is 2.5h.

[0015] Furthermore, the treatment solution comprises 300–500 mg·L⁻¹ -1 Ferric chloride and 350-600 mg·L -1 Sodium chloride. Preferably, the treatment solution comprises 350 mg / L. -1 Ferric chloride and 450 mg·L -1 Sodium chloride.

[0016] Further, the ratio of biochar to treatment solution is 5–15 g / mL. Preferably, the ratio of biochar to treatment solution is 10 g / mL.

[0017] Furthermore, the heat treatment is performed in two steps. The first step is low-temperature pre-firing at 80–120°C for 30–60 min with a heating rate of 5–10°C / min. The second step is high-temperature calcination at 250–350°C for 60–90 min with a heating rate of 2–5°C / min. Preferably, the low-temperature pre-firing temperature is 100°C for 45 min with a heating rate of 8°C / min, and the high-temperature calcination temperature is 320°C for 60 min with a heating rate of 3°C / min.

[0018] The present invention also provides an adsorbent material for treating organic wastewater prepared according to the above method.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] This invention significantly improves the regeneration performance of adsorbent materials, shortens treatment time, and increases treatment efficiency by adjusting the source and ratio of biochar raw materials and optimizing the preparation process.

[0021] This invention uses straw and cyanobacteria as raw materials, combined with biochar prepared by sodium hydroxide under high-temperature carbonization conditions. It has a rich pore structure and surface functional groups, which enhances the adsorption capacity for organic pollutants.

[0022] This invention utilizes biomass waste as raw material, reducing waste emissions and providing significant environmental benefits.

[0023] The method for preparing the adsorbent material provided by this invention is simple and easy to implement, suitable for large-scale industrial production, and has broad application prospects in the field of organic wastewater treatment. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 This is a process flow diagram of the preparation process of the adsorbent material for organic wastewater treatment according to the present invention. Detailed Implementation

[0026] This invention provides a method for preparing an adsorbent material for organic wastewater treatment, comprising the following steps:

[0027] S1. Dry and pulverize the straw and cyanobacteria separately, and pass them through an 80-100 mesh sieve to obtain straw powder and cyanobacteria powder;

[0028] S2. Mix straw powder and blue-green algae powder to obtain mixed powder, add sodium hydroxide and carbonize at high temperature under argon atmosphere to obtain biochar;

[0029] S3. The biochar is mixed with the treatment liquid, heat-treated, and cooled to obtain an adsorbent material for organic wastewater treatment.

[0030] In one embodiment, the drying temperature is 100℃~120℃ and the drying time is 8~12h.

[0031] In one embodiment, the mass ratio of the straw powder to the cyanobacteria powder is (3-5):1.

[0032] In one embodiment, the mass ratio of the straw powder to the cyanobacteria powder is 4:1.

[0033] Eutrophication accelerates the eutrophication of lakes, promotes cyanobacterial blooms and red tides, leading to deteriorating water quality and reduced dissolved oxygen, thus affecting the survival of aquatic plants and animals. Therefore, the resource-based treatment of cyanobacteria has a positive impact on solving this problem. To this end, this invention selects cyanobacteria as part of the raw material for biochar preparation, which can achieve resource-based treatment of cyanobacteria to a certain extent and reduce the adverse effects of eutrophication. Furthermore, the dehydrated, harvested cyanobacteria contain metal elements, which can be incorporated into the biochar through pyrolysis and subsequent biochar modification and activation, enhancing its adsorption capacity and positively impacting the microstructure of the material, thereby improving its adsorption and regeneration performance.

[0034] Furthermore, this invention imposes a relatively strict limit on the ratio of straw powder to cyanobacteria powder. This ratio ensures adsorption performance while controlling costs, optimizing pore structure and specific surface area, and guaranteeing the stability of biochar during carbonization. Too low a dosage of cyanobacteria powder results in low metal element content and poor pore structure in the biochar, while too high a dosage leads to pore blockage and a decrease in material adsorption performance.

[0035] In one embodiment, the mass ratio of sodium hydroxide to the mixed powder is (1-2):1.

[0036] In one embodiment, the mass ratio of sodium hydroxide to the mixed powder is 1.5:1.

[0037] Sodium hydroxide and potassium hydroxide are commonly used for biochar activation, but practical studies have shown that potassium hydroxide is not suitable for this invention. Experiments show that biochar activated with sodium hydroxide has a greater number of mesopores compared to that activated with potassium hydroxide. More mesopores are beneficial for improving the treatment effect of subsequent treatment solutions.

[0038] In one embodiment, the carbonization temperature is 800℃~900℃ and the carbonization time is 2~3h.

[0039] In one embodiment, the carbonization temperature is 850°C and the carbonization time is 2.5 hours.

[0040] In one embodiment, the treatment solution comprises 300–500 mg·L⁻¹ -1 Ferric chloride and 350-600 mg·L -1 Sodium chloride.

[0041] In one embodiment, the treatment solution comprises 350 mg·L -1 Ferric chloride and 450 mg·L -1 Sodium chloride.

[0042] The treatment solution can introduce functional groups, such as hydroxyl and carboxyl groups, onto the surface of biochar, which helps improve the adsorption capacity of biochar for organic pollutants. Sodium chloride in the treatment solution can regulate the ionic strength of the solution, thus affecting the interaction between the solution and biochar. Secondly, sodium chloride helps form more mesoporous structures during heat treatment, which are beneficial for adsorbing organic pollutants. Furthermore, sodium chloride promotes the precipitation of organic pollutants through salting-out, improving the adsorption efficiency of the material. Finally, the presence of sodium chloride helps the adsorbent material desorb the adsorbate more easily during regeneration, thereby improving regeneration efficiency, extending the service life of the adsorbent material, reducing replacement frequency and cost, and making its application in organic wastewater treatment more efficient and economical.

[0043] In one embodiment, the ratio of biochar to treatment liquid is 5–15 g / mL.

[0044] In one embodiment, the biochar to treatment liquid ratio is 10 g / mL.

[0045] This invention controls the iron oxide content in the material by limiting the feed-to-liquid ratio of biochar and treatment liquid. The research in this invention shows that the presence of iron oxide helps improve the adsorption and regeneration performance of the material; however, excessively high iron oxide content not only fails to further improve material performance but also leads to a significant reduction in specific surface area, thereby impairing the performance of the adsorption material. Therefore, this invention strictly limits the feed-to-liquid ratio of biochar and treatment liquid to maximize the specific surface area of ​​the adsorption material and improve adsorption performance. Furthermore, an appropriate feed-to-liquid ratio ensures sufficient contact between the biochar and the treatment liquid, improving the production efficiency of the adsorption material.

[0046] In one embodiment, the heat treatment is carried out in two steps. The first step is low-temperature pre-firing, with a temperature of 80-120°C, a holding time of 30-60 min, and a heating rate of 5°C / min-10°C / min. The second step is high-temperature calcination, with a temperature of 250°C-350°C, a holding time of 60-90 min, and a heating rate of 2°C / min-5°C / min.

[0047] In one embodiment, the low-temperature pre-calcination temperature is 100°C, the holding time is 45 min, and the heating rate is 8°C / min; the high-temperature calcination temperature is 320°C, the holding time is 60 min, and the heating rate is 3°C / min.

[0048] This invention improves the regeneration performance of adsorbent materials by employing a method of low-temperature pre-calcination, high-temperature calcination, and strict control of the step-by-step heat treatment heating rate. The low-temperature pre-calcination stage typically uses a relatively fast heating rate. This is because at low temperatures, volatile substances and moisture in the biochar need to be rapidly expelled to avoid excessive gas generation during the subsequent high-temperature calcination process, which could lead to sample expansion or rupture. Rapid heating also helps remove organic impurities and residues from the biochar, reducing interference with subsequent high-temperature treatment. The high-temperature calcination stage uses a slower heating rate, primarily to control the structure and pore formation of the biochar. Slow heating ensures that the biochar gradually forms a stable structure at high temperatures, avoiding structural damage caused by rapid temperature changes. Slow heating also contributes to uniform calcination, making the physical and chemical properties of the biochar more uniform, thereby improving its adsorption performance and stability.

[0049] Finally, the treatment solution must be used first, followed by heat treatment; the order of these two steps cannot be reversed. The ferric chloride and sodium chloride in the treatment solution can introduce functional groups onto the biochar surface, while simultaneously promoting the formation and development of pores on the biochar surface and within the biochar, increasing specific surface area and porosity. If high-temperature heat treatment is performed first, the chemicals in the treatment solution will have difficulty effectively penetrating and reacting, reducing the introduction of functional groups. Furthermore, changes in the pore structure of the biochar after high-temperature heat treatment will reduce the diffusion efficiency of the treatment solution within the biochar, affecting adsorption performance. Therefore, treating with the treatment solution first, followed by stepwise heat treatment, ensures the optimization of the biochar surface and internal structure, maximizing its adsorption performance and stability.

[0050] The present invention also provides an adsorbent material for treating organic wastewater prepared according to the above method.

[0051] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0052] Example 1: A method for preparing an adsorbent material for treating organic wastewater, comprising the following steps:

[0053] S1. Dry the straw at 100℃ for 8 hours, crush it, and pass it through an 80-mesh sieve to obtain straw powder; dry the cyanobacteria at 120℃ for 12 hours, crush it, and pass it through a 100-mesh sieve to obtain cyanobacteria powder.

[0054] S2. Mix straw powder and cyanobacteria powder evenly at a mass ratio of 4:1 to obtain mixed powder. Mix sodium hydroxide and mixed powder evenly at a mass ratio of 1.5:1. Carbonize at 850℃ for 2.5h under argon conditions to obtain biochar.

[0055] S3. The biochar and the treatment liquid are mixed evenly at a ratio of 10 g / mL. The temperature is increased to 100°C at a rate of 8°C / min and held for 45 min. Then the temperature is increased to 320°C at a rate of 3°C / min and held for 60 min. The mixture is then cooled to obtain the adsorbent material for organic wastewater treatment.

[0056] The treatment solution is prepared by mixing an aqueous solution of ferric chloride and an aqueous solution of sodium chloride, wherein the concentration of ferric chloride is 350 mg·L⁻¹. -1 The concentration of sodium chloride is 450 mg·L⁻¹. -1 .

[0057] Example 2: A method for preparing an adsorbent material for organic wastewater treatment, comprising the following steps:

[0058] S1. Dry the straw at 100℃ for 8 hours, crush it, and pass it through an 80-mesh sieve to obtain straw powder; dry the cyanobacteria at 120℃ for 12 hours, crush it, and pass it through a 100-mesh sieve to obtain cyanobacteria powder.

[0059] S2. Mix straw powder and cyanobacteria powder evenly at a mass ratio of 3:1 to obtain mixed powder. Mix sodium hydroxide and mixed powder evenly at a mass ratio of 2:1. Carbonize at 900℃ for 2 hours under argon conditions to obtain biochar.

[0060] S3. The biochar and the treatment liquid are mixed evenly at a ratio of 15 g / mL. The temperature is increased to 120°C at a rate of 5°C / min and held for 60 min. Then the temperature is increased to 350°C at a rate of 2°C / min and held for 90 min. The mixture is then cooled to obtain the adsorbent material for organic wastewater treatment.

[0061] The treatment solution is prepared by mixing an aqueous solution of ferric chloride and an aqueous solution of sodium chloride, wherein the concentration of ferric chloride is 350 mg·L⁻¹. -1 The concentration of sodium chloride is 450 mg·L⁻¹. -1 .

[0062] Example 3: A method for preparing an adsorbent material for organic wastewater treatment, comprising the following steps:

[0063] S1. Dry the straw at 100℃ for 8 hours, crush it, and pass it through an 80-mesh sieve to obtain straw powder; dry the cyanobacteria at 120℃ for 12 hours, crush it, and pass it through a 100-mesh sieve to obtain cyanobacteria powder.

[0064] S2. Mix straw powder and cyanobacteria powder evenly at a mass ratio of 5:1 to obtain mixed powder. Mix sodium hydroxide and mixed powder evenly at a mass ratio of 1:1. Carbonize at 800℃ for 3 hours under argon conditions to obtain biochar.

[0065] S3. Mix the biochar and the treatment liquid at a ratio of 5 g / mL, raise the temperature to 80°C at a rate of 10°C / min, hold for 30 min, then raise the temperature to 250°C at a rate of 5°C / min, hold for 60 min, and cool to obtain the adsorbent material for organic wastewater treatment.

[0066] The treatment solution is prepared by mixing an aqueous solution of ferric chloride and an aqueous solution of sodium chloride, wherein the concentration of ferric chloride is 350 mg·L⁻¹. -1 The concentration of sodium chloride is 450 mg·L⁻¹. -1 .

[0067] Comparative Example 1

[0068] Same as Example 1, except that: the straw powder is passed through a 20-mesh sieve and the cyanobacteria powder is passed through a 40-mesh sieve.

[0069] Comparative Example 2

[0070] Same as Example 1, except that: no blue-green algae powder was used.

[0071] Comparative Example 3

[0072] Same as Example 1, except that the mass ratio of straw powder to cyanobacteria powder is 1:1.

[0073] Comparative Example 4

[0074] Same as Example 1, except that sodium hydroxide is replaced with an equal amount of potassium hydroxide.

[0075] Comparative Example 5

[0076] Same as Example 1, except that: the heat treatment method is: heat to 320°C at a heating rate of 3°C / min, hold for 60 minutes, and then cool to obtain the adsorbent material for organic wastewater treatment.

[0077] Comparative Example 6

[0078] Same as Example 1, except that: the temperature is raised to 100°C at a heating rate of 3°C / min, held for 45 min, then raised to 320°C at a heating rate of 8°C / min, held for 60 min, and then cooled to obtain the adsorbent material for organic wastewater treatment.

[0079] Comparative Example 7

[0080] A method for preparing an adsorbent material for treating organic wastewater includes the following steps:

[0081] S1. Dry the straw at 100℃ for 8 hours, crush it, and pass it through an 80-mesh sieve to obtain straw powder; dry the cyanobacteria at 120℃ for 12 hours, crush it, and pass it through a 100-mesh sieve to obtain cyanobacteria powder.

[0082] S2. Mix straw powder and cyanobacteria powder evenly at a mass ratio of 4:1 to obtain mixed powder. Mix sodium hydroxide and mixed powder evenly at a mass ratio of 1.5:1. Carbonize at 850℃ for 2.5h under argon conditions to obtain biochar.

[0083] S3. The biochar is heated to 100°C at a heating rate of 8°C / min and held for 45 min. Then it is heated to 320°C at a heating rate of 3°C / min and held for 60 min. After cooling, it is mixed with the treatment liquid at a ratio of 10 g / mL and stirred evenly for 60 min. Then it is dried to obtain the adsorption material for organic wastewater treatment.

[0084] The treatment solution is prepared by mixing an aqueous solution of ferric chloride and an aqueous solution of sodium chloride, wherein the concentration of ferric chloride is 350 mg·L⁻¹. -1 The concentration of sodium chloride is 450 mg·L⁻¹. -1 .

[0085] Test Example 1

[0086] The performance of the adsorbent materials for organic wastewater treatment obtained in the examples and comparative examples was tested. Unless otherwise specified, all experiments were repeated three times. Analysis of variance (ANOVA) and Duncan's multiple comparison analysis were performed using SPSS 21.0, and the results are expressed as mean ± standard deviation. The test methods are as follows:

[0087] 0.2 g of adsorbent material for organic wastewater treatment was weighed and added to 100 mL of methylene blue solution with a concentration of 100 mg / L. The reaction was carried out in a 250 mL Erlenmeyer flask. The sample was placed on a magnetic stirrer and stirred at an appropriate rate. After the reaction reached equilibrium time, the sample was centrifuged. The supernatant was filtered through a 0.22 μm filter and the absorbance was measured. The concentration of methylene blue after adsorption was calculated by converting it into a standard curve, and the adsorption rate was calculated.

[0088] The adsorbent material for treating organic wastewater containing methylene blue was regenerated using 3% H₂O₂ at a regeneration temperature of 30℃ for 4 hours. After regeneration, the adsorbent material was washed three times with distilled water, dried, and then subjected to a second adsorption experiment. This process was repeated five times, and the regeneration rate was calculated.

[0089] The test results are as follows:

[0090] Adsorption rate, % Equilibrium time, min Regeneration rate, % Example 1 97.38±2.0ab 54.42±1.73g 74.55±1.59a Example 2 96.95±1.6b 52.73±1.82g 74.18±1.23a Example 3 97.87±1.3ab 52.11±2.18g 74.90±1.72a Comparative Example 1 70.11±2.1g 73.47±1.46a 61.99±2.31e Comparative Example 2 77.90±1.4f 68.03±1.01b 63.17±1.66d Comparative Example 3 80.83±1.9e 63.67±1.25d 62.91±2.28d Comparative Example 4 98.55±2.0a 65.30±2.04c 64.43±2.05c Comparative Example 5 89.59±1.7d 58.77±1.50e 65.70±1.54b Comparative Example 6 92.51±1.4c 57.14±1.67f 65.06±1.87bc Comparative Example 7 96.93±1.37b 63.21±1.06d 61.25±1.15e

[0091] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing an adsorbent material for treating organic wastewater, characterized in that, Includes the following steps: S1. Dry and pulverize the straw and cyanobacteria separately, and pass them through an 80-100 mesh sieve to obtain straw powder and cyanobacteria powder; S2. Mix straw powder and blue-green algae powder to obtain mixed powder, add sodium hydroxide and carbonize at high temperature under argon atmosphere to obtain biochar; S3. The biochar is mixed with the treatment liquid, heat-treated, and cooled to obtain an adsorbent material for organic wastewater treatment. The treatment solution contains 300~500 mg·L -1 Ferric chloride and 350~600 mg·L -1 Sodium chloride; The heat treatment is carried out in two steps. The first step is low-temperature pre-firing, with a temperature of 80~120℃, a holding time of 30~60 min, and a heating rate of 5℃ / min~10℃ / min. The second step is high-temperature calcination, with a temperature of 250℃~350℃, a holding time of 60~90 min, and a heating rate of 2℃ / min~5℃ / min. The mass ratio of the straw powder to the blue-green algae powder is (3~5):1; The ratio of biochar to treatment liquid is 5~15 g / mL.

2. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that... The drying temperature is 100℃~120℃, and the drying time is 8~12 h.

3. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that, The mass ratio of the straw powder to the cyanobacteria powder is 4:

1.

4. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that, The mass ratio of sodium hydroxide to the mixed powder is (1~2):

1.

5. The method for preparing an adsorbent material for organic wastewater treatment according to claim 4, characterized in that, The mass ratio of sodium hydroxide to the mixed powder is 1.5:

1.

6. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that, The carbonization temperature is 800℃~900℃, and the carbonization time is 2~3 h.

7. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that, The treatment solution contains 350 mg·L -1 Ferric chloride and 450 mg·L -1 Sodium chloride.

8. The method for preparing an adsorbent material for organic wastewater treatment according to claim 1, characterized in that, The low-temperature pre-calcination temperature is 100℃, the holding time is 45 min, and the heating rate is 8℃ / min. The high-temperature calcination temperature is 320℃, the holding time is 60 min, and the heating rate is 3℃ / min.

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