一种零价铁负载生物炭高效降解全氟辛烷磺酸的方法

Abstract

This invention relates to the field of wastewater treatment, specifically to a method for the efficient degradation of perfluorooctane sulfonic acid (PFOS) using zero-valent iron-supported biochar. The method includes the following steps: A mixture of bio-based fine powder, ferric chloride, and water is subjected to high-temperature carbonization under a protective gas atmosphere to obtain zero-valent iron-supported biochar. This zero-valent iron-supported biochar is then used as an adsorbent to adsorb and remove PFOS from the water. The adsorbed zero-valent iron-supported biochar is then added to a ball mill jar and ball-milled along with the milling media, resulting in the degradation of PFOS. The zero-valent iron-supported biochar material of this invention not only efficiently adsorbs typical organic pollutants in water, but also features mild and simple reaction conditions, providing new ideas and methods for wastewater and post-use biochar treatment, and possesses significant theoretical and practical value.

Description

Technical Field

[0001] This invention relates to the field of organic matter degradation technology, specifically to a method for the efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar. Background Technology

[0002] The numerous high-energy CF bonds in the molecular structure of perfluoroalkyl and polyfluoroalkyl substances (PFAS) endow them with physicochemical properties such as hydrophobicity, high-temperature resistance, and chemical corrosion resistance, making them widely used in the production of fire-fighting foams, metal electroplating, and protective coatings. However, the large-scale production and use of PFASs have also led to their widespread detection in surface water, groundwater, drinking water, human tissues, and serum. Perfluorooctane sulfonic acid (PFOS) is one of the most important PFASs. Studies have shown that ingestion of PFOS exceeding a certain level may have harmful effects on human and animal health, including immunotoxicity, hepatotoxicity, nephrotoxicity, cardiotoxicity, reproductive toxicity, and neurotoxicity, raising widespread concern about its health risks. Therefore, PFOS elimination technologies have received considerable attention.

[0003] Currently, methods for PFOS degradation mainly include electrochemical degradation, physical adsorption, microbial degradation, and photocatalytic degradation. Physical adsorption is considered a promising method for removing perfluorooctane sulfonate (PFOS) from water, as it is directly operable and relatively inexpensive. However, its drawbacks include the inability to effectively decompose PFOS by merely transferring it from water to a solid phase. Electrochemical degradation consumes excessive power and the cathode is prone to passivation. Microbial degradation is time-consuming, difficult to control, and microorganisms have relatively weak PFOS degradation capabilities, easily generating secondary biological organic pollutants during the degradation process. Photocatalytic degradation catalysts are expensive, and the combination of photogenerated holes and electrons on the catalyst leads to low light energy utilization. However, few methods are available for the degradation of PFOS in solids. Therefore, there is an urgent need to develop comprehensive, environmentally friendly, and low-cost treatment technologies to simultaneously treat PFOS in both liquids and solids. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for the efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar, which has the advantages of being green, efficient, and low-cost.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for the efficient degradation of perfluorooctane sulfonic acid by zero-valent iron-supported biochar, comprising the following steps:

[0006] S1. After cleaning and drying the bio-based material, crush and sieve it to obtain bio-based fine powder;

[0007] S2. Ferric chloride, bio-based fine powder, and water are mixed and stirred in a mass ratio of 1:(1-10):(30-50), then dried, ground, and sieved. The mixture is then carbonized in a protective gas at a high temperature of 500-900℃ and sieved to obtain zero-valent iron-supported biochar.

[0008] S3. Add zero-valent iron-loaded biochar to the wastewater containing perfluorooctane sulfonic acid and stir to allow the zero-valent iron-loaded biochar to adsorb the perfluorooctane sulfonic acid, thus obtaining the adsorbed zero-valent iron-loaded biochar.

[0009] S4. Add the adsorbed zero-valent iron-loaded biochar to the ball mill jar and ball mill it together with the ball milling media. The ball milling speed is 200-600 rpm and the time is 180-480 min. Perfluorooctane sulfonic acid is degraded.

[0010] Further improvements to the method of efficiently degrading perfluorooctane sulfonic acid with zero-valent iron-supported biochar:

[0011] Preferably, the bio-based material is one of corn stalks, bamboo, rice straw, sugarcane bagasse, and wood.

[0012] Preferably, the drying temperature in step S2 is 95-105℃ and the drying time is 48-72h.

[0013] Preferably, the sieving in steps S1 and S2 is done through a 90-100 mesh sieve.

[0014] Preferably, the high-temperature carbonization time in step S2 is 60-120 min, and the heating rate is 5-10℃ / min.

[0015] Preferably, the protective gas in step S2 is one of nitrogen and an inert gas.

[0016] Preferably, in step S3, the concentration of perfluorooctane sulfonic acid in the wastewater to be treated is 30 μmol / L-150 μmol / L, and the dosage of zero-valent iron-supported biochar in the wastewater to be treated is 0.2 g / L-20 g / L.

[0017] Preferably, in step S3, the temperature at which the zero-valent iron-supported biochar is mixed with the wastewater containing perfluorooctane sulfonic acid is 20℃-38.5℃, and the mixture is stirred at a speed not exceeding 180 rpm for more than 60 minutes.

[0018] Preferably, in step S4, the grinding jar and the grinding media are made of agate, and the grinding media are small balls with a diameter of 4-10 mm.

[0019] Preferably, in step S4, the mass ratio of the adsorbed zero-valent iron-supported biochar material to the ball milling media is 1:(50-100).

[0020] The advantages of this invention compared to the prior art are as follows:

[0021] 1) Zero-valent iron (ZVI) and its derivatives exhibit good adsorption properties for organic matter due to their large specific surface area, small particle size, abundant active sites, and strong reactivity. Furthermore, ZVI possesses excellent reducing and electron transfer-promoting capabilities, providing potential for the adsorption and degradation of PFOS. However, ZVI has poor stability and its surface is easily oxidized, forming a passivation layer that reduces reactivity. Simultaneously, ZVI particles tend to agglomerate, reducing the number of active sites on their surface and the effective contact area with pollutants, thus decreasing their activity.

[0022] Biochar is widely used in environmental remediation due to its abundant material sources, simple and efficient preparation methods, low cost, and excellent adsorption performance, making it a promising adsorbent material. Furthermore, biochar's porous structure allows it to disperse ZVI, improving agglomeration and passivation, and increasing reactive sites, thereby enhancing the reactivity and stability of ZVI. In addition, biochar can form an iron-carbon microelectrolysis system with ZVI, accelerating electron transfer rates. During the calcination of biochar, the reducing gases generated under anaerobic conditions and the reducing properties of the biochar material are utilized to remove Fe... 3+ The reduction to zero-valent iron provides the possibility for synthesizing biochar materials loaded with zero-valent iron for the adsorption and degradation of PFOS. Preferably, the biochar is produced using bio-based materials as raw materials, and the bio-based biochar is modified with ferric chloride. By loading the biochar material with zero-valent iron, the efficiency of organic polluted water treatment is effectively improved, while realizing the high-efficiency and low-cost resource utilization of bio-based materials.

[0023] This invention utilizes zero-valent iron-loaded biochar as an adsorbent, exhibiting high removal efficiency for perfluorooctane sulfonate (PFOS) in water. PFOS is first adsorbed, followed by mechanochemical degradation. The mechanochemical (MC) method degrades organic pollutants in the ball mill jar through various mechanical stresses (such as collision, compression, shearing, and friction) between the balls, materials, and the grinding pot. Furthermore, the use of grinding media (e.g., Al₂O₃ and metals) can improve the efficiency of MC degradation of organic pollutants, making it possible to simultaneously promote PFOS degradation through ball milling after adsorption using zero-valent iron-loaded biochar. In practical groundwater and surface water applications, zero-valent iron and biochar undergo anaerobic and aerobic aging processes. The zero-valent iron-loaded biochar prepared in this invention maintains good PFOS removal efficiency even after simulated aging.

[0024] The raw materials of this invention are widely available, and the preparation method is simple and easy to implement. It provides new ideas and methods for the degradation and removal of organic matter in water, and constructs an adsorption separation and degradation system to achieve rapid removal of perfluorooctane sulfonic acid in water. It has important theoretical and practical value. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the zero-valent iron-supported biochar prepared in Example 1.

[0026] Figure 2 This is a scanning electron microscope image of the aerobic-aged zero-valent iron-supported biochar prepared in Example 2.

[0027] Figure 3 Scanning electron microscopy (SEM) image of the anaerobic-aged zero-valent iron-supported biochar prepared in Example 3;

[0028] Figure 4 Scanning electron microscopy (SEM) image of the anaerobic-aged zero-valent iron-supported biochar prepared in Example 4.

[0029] Figure 5 The degradation rate of perfluorooctane sulfonic acid (PFOS) with ball milling time is shown in Examples 1-4 after the original zero-valent iron-supported biochar and the aged zero-valent iron-supported biochar adsorbed PFOS.

[0030] Figure 6 The adsorption efficiencies of the original zero-valent iron-supported biochar and the aged zero-valent iron-supported biochar in Examples 1-4 are shown.

[0031] Figure 7 The adsorption efficiency of zero-valent iron-supported biochar prepared in Example 1 under interference conditions is shown in Figures 5-11.

[0032] Figure 8 The degradation efficiency of zero-valent iron-supported biochar prepared in Example 1 under interference conditions is shown for 5, 10, and 11. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing zero-valent iron-supported biochar, the specific steps of which are as follows:

[0036] S1. Wash and dry the corn stalks, crush them, and pass them through a 100-mesh sieve to obtain fine corn stalk powder;

[0037] S2. Mix 10g of ferric chloride and 10g of corn stalk powder with 500mL of water, stir, dry in an oven at 105℃ for 72h, grind, pass through a 100-mesh sieve, then place in a quartz boat, and then place in a tube furnace for pyrolysis. After passing nitrogen gas for 10min in a sealed state, heat to 900℃ at a rate of 5℃ / min, maintain the temperature for 2h, cool to room temperature, grind, and pass through a 100-mesh sieve to obtain zero-valent iron-supported biochar.

[0038] S3. Take 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution, add 0.03 g of zero-valent iron-supported biochar, and shake sequentially at 38.5℃ and 180 rpm for 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min. During shaking, determine the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 6 (as shown);

[0039] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of zero-valent iron-supported biochar was added. The mixture was shaken for 120 min at 38.5℃ and 180 rpm to obtain adsorbed zero-valent iron-supported biochar. All the adsorbed zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of 10 mm and 6 mm diameter agate balls. The ball mill jar was placed in a planetary ball mill, and the speed was set to 350 rpm. During the ball milling process, at milling times of 20 min, 40 min, 60 min, 120 min, 180 min, 240 min, and 480 min, 0.1 g of the milled solid was taken and added to 30 mL of methanol. The mixture was then extracted in an 80℃ oven for 4 h. After cooling to room temperature, it was filtered. The filtered liquid was brought to a final volume of 30 mL. The concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the relationship between the degradation rate of perfluorooctane sulfonic acid and the ball milling time was calculated. Figure 5 As shown. Take another solid after ball milling for 480 min and add methanol to it. Add 30 mL of methanol to 1 g of ball-milled solid and place it in an 80 ℃ oven for 4 h to extract. After cooling to room temperature, filter it. Wash the filtered solid with methanol and deionized water in sequence and then dry it to obtain recovered zero-valent iron supported biochar for later use.

[0040] Example 2

[0041] S1. Weigh 4g of the zero-valent iron-supported biochar prepared in Example 1 and place it in a glass bottle. Add 100mL of deionized water and stir at 160rpm for 72h in an open-air environment. Then take it out and dry it to obtain aerobic-aged zero-valent iron-supported biochar.

[0042] S2. Take 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution and add 0.03 g of aerobic-aged zero-valent iron-supported biochar. Shake at 38.5℃ and 180 rpm for 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min to obtain aerobic-aged zero-valent iron-supported biochar after adsorption. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 6 (as shown);

[0043] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of aerobic-aged zero-valent iron-supported biochar was added. The mixture was shaken for 120 min at 38.5 °C and 180 rpm to obtain aerobic-aged zero-valent iron-supported biochar after adsorption. All of the aerobic-aged zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of 10 mm and 6 mm diameter agate balls. The ball mill jar was placed in a planetary ball mill, and the rotation speed was set to 350 rpm. At ball milling times of 20 min, 40 min, 60 min, 120 min, 180 min, 240 min, and 480 min, 0.1 g of the ball-milled solid was added to 30 mL of methanol and extracted in an 80℃ oven for 4 h. After cooling to room temperature, the mixture was filtered, and the filtered liquid was diluted to 30 mL. The concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The relationship between the degradation efficiency of perfluorooctane sulfonic acid and ball milling time was calculated. Figure 5 As shown.

[0044] Example 3

[0045] S1. Weigh 4g of the zero-valent iron-supported biochar prepared in Example 1 and place it in a glass bottle. Add 100mL of deoxygenated water, seal the bottle mouth with a rubber stopper, and stir at 160rpm for 50 days under anaerobic conditions to obtain anaerobic aged zero-valent iron-supported biochar.

[0046] S2. Take 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution and add 0.03 g of anaerobic-aged zero-valent iron-supported biochar. Shake at 38.5℃ and 180 rpm for 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min to obtain the anaerobic-aged zero-valent iron-supported biochar after adsorption. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 6 (as shown);

[0047] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of anaerobic-aged zero-valent iron-supported biochar was added. The mixture was shaken for 120 min at 38.5℃ and 180 rpm to obtain anaerobic-aged zero-valent iron-supported biochar after adsorption. All of the anaerobic-aged zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of 10 mm and 6 mm diameter agate balls. The ball mill jar was placed in a planetary ball mill, and the rotation speed was set to 350 rpm. At ball milling times of 20 min, 40 min, 60 min, 120 min, 180 min, 240 min, and 480 min, 0.1 g of the ball-milled solid was added to 30 mL of methanol and extracted in an 80℃ oven for 4 h. After cooling to room temperature, the mixture was filtered, and the filtered liquid was diluted to 30 mL. The concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The relationship between the degradation rate of perfluorooctane sulfonic acid and ball milling time was calculated. Figure 5 As shown.

[0048] Example 4

[0049] S1. Weigh 4g of the zero-valent iron-supported biochar prepared in Example 1 and place it in a glass bottle. Add 100mL of deoxygenated water, seal the bottle mouth with a rubber stopper, and stir at 160rpm for 90d under anaerobic conditions to obtain anaerobic aged zero-valent iron-supported biochar.

[0050] S2. Take 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution and add 0.03 g of anaerobic-aged zero-valent iron-supported biochar. Shake at 38.5℃ and 180 rpm for 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min to obtain the anaerobic-aged zero-valent iron-supported biochar after adsorption. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 6 (as shown);

[0051] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of anaerobic-aged zero-valent iron-supported biochar was added. The mixture was shaken for 120 min at 38.5℃ and 180 rpm to obtain anaerobic-aged zero-valent iron-supported biochar after adsorption. All of the anaerobic-aged zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of 10 mm and 6 mm diameter agate balls. The ball mill jar was placed in a planetary ball mill, and the rotation speed was set to 35 rpm. At 0 rpm, during ball milling, at times of 20 min, 40 min, 60 min, 120 min, 180 min, 240 min, and 480 min, 0.1 g of the ball-milled solid was added to 30 mL of methanol and extracted in an 80℃ oven for 4 h. After cooling to room temperature, the mixture was filtered, and the liquid was diluted to 30 mL. The concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS). The relationship between the degradation rate of perfluorooctane sulfonic acid and ball milling time was calculated. Figure 5 As shown.

[0052] Example 5

[0053] S1. Prepare a mixed solution of 100 μmol / L perfluorooctane sulfonic acid and 0.25 mg / L humic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0054] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of zero-valent iron-supported biochar prepared in Example 1 was added. The mixture was shaken for 120 min at 38.5 °C and 180 rpm to obtain adsorbed zero-valent iron-supported biochar. All the adsorbed zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of agate balls with diameters of 10 mm and 6 mm. The ball mill jar was placed in a planetary ball mill, and the speed was set to 350 rpm. During the ball milling process, at 480 min, 0.1 g of the ball-milled solid was taken and added to 30 mL of methanol. The mixture was then extracted in an 80 °C oven for 4 h. After cooling to room temperature, it was filtered. The filtered liquid was diluted to 30 mL, and the concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry. The relationship between the degradation rate of perfluorooctane sulfonic acid and the ball milling time was calculated. Figure 8 As shown.

[0055] Example 6

[0056] S1. Prepare a mixed solution of 100 μmol / L perfluorooctane sulfonic acid and 0.5 mg / L humic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0057] Example 7

[0058] S1. Prepare a mixed solution of 100 μmol / L perfluorooctane sulfonic acid and 1 mg / L humic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0059] Example 8

[0060] S1. Prepare a mixed solution with concentrations of 100 μmol / L perfluorooctane sulfonic acid, 50 μmol / L acetic acid, 50 μmol / L propionic acid, 50 μmol / L butyric acid, 50 μmol / L valeric acid, and 50 μmol / L oxalic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5℃ and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0061] Example 9

[0062] S1. Prepare a mixed solution with concentrations of 100 μmol / L perfluorooctane sulfonic acid, 100 μmol / L acetic acid, 100 μmol / L propionic acid, 100 μmol / L butyric acid, 100 μmol / L valeric acid, and 100 μmol / L oxalic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0063] Example 10

[0064] S1. Prepare a mixed solution with concentrations of 100 μmol / L perfluorooctane sulfonic acid, 150 μmol / L acetic acid, 150 μmol / L propionic acid, 150 μmol / L butyric acid, 150 μmol / L valeric acid, and 150 μmol / L oxalic acid. Take 30 mL of the mixed solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0065] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of zero-valent iron-supported biochar prepared in Example 1 was added. The mixture was shaken for 120 min at 38.5 °C and 180 rpm to obtain adsorbed zero-valent iron-supported biochar. All the adsorbed zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of agate balls with diameters of 10 mm and 6 mm. The ball mill jar was placed in a planetary ball mill, and the speed was set to 350 rpm. During the ball milling process, at 480 min, 0.1 g of the ball-milled solid was taken and added to 30 mL of methanol. The mixture was then extracted in an 80 °C oven for 4 h. After cooling to room temperature, it was filtered. The filtered liquid was diluted to 30 mL, and the concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry. The relationship between the degradation rate of perfluorooctane sulfonic acid and the ball milling time was calculated. Figure 8 As shown.

[0066] Example 11

[0067] S1. Prepare a 100 μmol / L perfluorooctane sulfonic acid solution using actual industrial wastewater. Take 30 mL of the solution and add 0.03 g of zero-valent iron-supported biochar prepared in Example 1. Shake at 38.5 °C and 180 rpm for 120 min. Measure the concentration of residual perfluorooctane sulfonic acid in the solution using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) and calculate its adsorption efficiency (e.g., ...). Figure 7 (As shown).

[0068] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of zero-valent iron-supported biochar prepared in Example 1 was added. The mixture was shaken for 120 min at 38.5 °C and 180 rpm to obtain adsorbed zero-valent iron-supported biochar. All the adsorbed zero-valent iron-supported biochar was added to a 50 mL ball mill jar, along with 50 g of agate balls with diameters of 10 mm and 6 mm. The ball mill jar was placed in a planetary ball mill, and the speed was set to 350 rpm. During the ball milling process, at 480 min, 0.1 g of the ball-milled solid was taken and added to 30 mL of methanol. The mixture was then extracted in an 80 °C oven for 4 h. After cooling to room temperature, it was filtered. The filtered liquid was diluted to 30 mL, and the concentration of residual perfluorooctane sulfonic acid in the solution was determined using high-performance liquid chromatography-mass spectrometry. The relationship between the degradation rate of perfluorooctane sulfonic acid and the ball milling time was calculated. Figure 8 As shown.

[0069] Table 1 shows the specific surface area and pore structure parameters of the zero-valent iron-supported biochar prepared in Examples 1-4.

[0070] Table 1

[0071]

[0072]

[0073] As shown in Table 1, Example 1 has a well-developed pore structure and a large specific surface area, which allows for greater adsorption of perfluorooctane sulfonic acid. The zero-valent iron-supported biochar of Examples 2-4, obtained by aging Example 1, still has a high specific surface area, indicating that the zero-valent iron-supported biochar has good stability.

[0074] Figures 1 to 4These are SEM images of zero-valent iron (ZFe)-supported biochar from Example 1, aerobic-aged ZFe-supported biochar from Example 2, anaerobic-aged ZFe-supported biochar from Example 3, and anaerobic-aged ZFe-supported biochar from Example 4. The results show that the ZFe-supported biochar from Example 1 exhibits a spherical structure composed of nanosheets with smooth, flat boundaries, a well-defined, regular, and clearly visible pore structure, and no aggregation or overlap. This indicates that the biochar can serve as an effective carrier for dispersing ZFe, allowing for uniform dispersion of ZFe particles. As can be seen from this image, the role of biochar is crucial. The abundant micropores in biochar provide a large specific surface area and pore volume, promoting the adsorbent's capacity to accommodate more organic matter. Biochar and iron themselves also possess adsorption capacity, adsorbing and fixing perfluorooctane sulfonic acid (PFOS) in the solution. Its presence effectively prevents the easy aggregation of ZFe, avoiding its continuous aggregation during formation and reaction, increasing the dispersibility of ZFe particles, thereby increasing their surface area and effective reaction sites. In Example 2, the pore edges of the zero-valent iron (ZFe)-supported biochar aged under aerobic conditions thinned. In Examples 3 and 4, the pore edges of the ZFe-supported biochar aged under anaerobic conditions thickened, possibly due to the formation of ferric hydroxide. Comparing Examples 3 and 4, it can be seen that the pore framework did not change significantly with increasing anaerobic time. The comparison shows that aerobic and anaerobic aging have almost no significant impact on the structure of the ZFe-supported biochar, indicating that its structure is relatively stable. Figures 1 to 4 Aging has almost no effect on the crystal structure of zero-valent iron-supported biochar. In summary, the adsorption and degradation performance of this zero-valent iron-supported biochar remains stable after long-term placement in groundwater and surface water, and its performance does not deteriorate with prolonged placement time.

[0075] Figure 5 This describes the effect of zero-valent iron-supported biochar in Examples 1-4 on the degradation of perfluorooctane sulfonic acid using an adsorption-mechanical-chemical method. Figure 5 It can be seen that both the original zero-valent iron-supported biochar and the aged zero-valent iron-supported biochar can efficiently degrade perfluorooctane sulfonic acid within 20 minutes.

[0076] Zero-valent iron-supported biochar was added to a solution containing perfluorooctane sulfonic acid (PFOS) and shaken. The adsorption efficiency was calculated by measuring the concentration of PFOS in the solution after adsorption. The PFOS adsorption efficiencies of the zero-valent iron-supported biochar in Example 1, the aerobically aged zero-valent iron-supported biochar in Example 2, the anaerobically aged zero-valent iron-supported biochar 1 in Example 3, and the anaerobically aged zero-valent iron-supported biochar 2 in Example 4 are shown below. Figure 6 As shown. By Figure 6It can be seen that after 120 min of adsorption, the adsorption efficiency of perfluorooctane sulfonic acid (PFOS) by the biochar prepared in Example 1 was 99.91%, that of the biochar prepared in Example 2 was 81.95%, that of the biochar prepared in Example 3 was 92.70%, and that of the biochar prepared in Example 4 was 96.74%. The adsorption effect gradually increased with increasing anaerobic time because the adsorption capacity of the oxidation products formed by the oxidation of zero-valent iron after anaerobic conditions is similar to that of the original zero-valent iron on the biochar. Examples 2, 3, and 4 are aged biochar. By comparing the adsorption efficiency, it can be seen that the aged biochar still has a good adsorption effect on PFOS. The zero-valent iron-loaded biochar prepared in this invention is suitable for the remediation of surface water and groundwater in practical applications.

[0077] Figure 7 Examples 5-11 illustrate the competitive adsorption effect of zero-valent iron-supported biochar prepared in Example 1 on perfluorooctane sulfonic acid under interference conditions. Figure 7 It can be seen that the adsorption efficiency of Example 5 is 97.36%, that of Example 6 is 73.85%, that of Example 7 is 27.61%, that of Example 8 is 99.97%, that of Example 9 is 96.89%, that of Example 10 is 87.95%, and that of Example 11 is 80.61%. Zero-valent iron-supported biochar exhibits an adsorption efficiency of over 87% under the interference of volatile fatty acids, and over 70% under relatively low humic acid interference. The adsorption efficiency in actual industrial wastewater is 80.61%, indicating that zero-valent iron-supported biochar can effectively resist interference from humic acid and volatile fatty acids, and still maintains good adsorption capacity in actual industrial wastewater.

[0078] Figure 8 Examples 5, 10, and 11 illustrate the competitive degradation of perfluorooctane sulfonic acid (PFOS) using zero-valent iron-supported biochar prepared in Example 1 under interference conditions. The degradation efficiency was 92.29% in Example 5, 99.96% in Example 10, and 99.97% in Example 11. This indicates that zero-valent iron-supported biochar exhibits good resistance to interference from humic acids and volatile fatty acids when degrading PFOS, and still maintains good adsorption capacity in actual industrial wastewater.

[0079] Example 12

[0080] The recycled zero-valent iron-supported biochar from Example 1 was reused, and its adsorption and degradation efficiencies were tested.

[0081] 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken and 0.03 g of the zero-valent iron supported biochar from Example 1 was added. The mixture was shaken at 38.5 °C and 180 rpm for 60 min to obtain the zero-valent iron supported biochar after adsorption. The concentration of residual perfluorooctane sulfonic acid in the solution was determined by high performance liquid chromatography-mass spectrometry, and its adsorption efficiency was calculated.

[0082] In addition, 30 mL of a 100 μmol / L perfluorooctane sulfonic acid solution was taken, and 0.5 g of the recovered zero-valent iron-supported biochar from Example 1 was added. The mixture was shaken for 120 min at 38.5 °C and 180 rpm to obtain the adsorbed zero-valent iron-supported biochar. All the adsorbed zero-valent iron-supported biochar was added to a 50 mL ball mill jar, and 50 g of agate balls with diameters of 10 mm and 6 mm were added. The ball mill jar was placed in a planetary ball mill, and the speed was set to 350 rpm. After 60 min of ball milling, 0.1 g of the ball-milled solid was added to 30 mL of methanol, and then the mixture was placed in an 80 °C oven for extraction for 4 h. After cooling to room temperature, the mixture was filtered, and the filtered liquid was diluted to 30 mL. The concentration of residual perfluorooctane sulfonic acid in the solution was determined by high performance liquid chromatography-mass spectrometry, and the degradation rate of perfluorooctane sulfonic acid was calculated. Take another solid after ball milling for 60 min and add methanol to it. Add 30 mL of methanol to 1 g of ball-milled solid and place it in an 80 ℃ oven for 4 h to extract. After cooling to room temperature, filter it. Wash the filtered solid with methanol and deionized water in sequence and then dry it to obtain the recovered zero-valent iron-supported biochar for later use.

[0083] Repeat the above adsorption-degradation-desorption process and calculate the adsorption effect of zero-valent iron-supported biochar on the degradation of perfluorooctane sulfonic acid when it is recycled 2-4 times.

[0084] Tests showed that the adsorption efficiency of the zero-valent iron-supported biochar prepared in Example 1 was 99.99% and the degradation efficiency was 99.90% after one cycle. The adsorption efficiency was 99.99% after the second cycle, 99.99% after the third cycle, and 99.99% after the fourth cycle. The zero-valent iron-supported biochar has good cyclic adsorption performance for PFOS, and the degradation efficiency is basically not reduced after one cycle.

[0085] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for the efficient degradation of perfluorooctane sulfonic acid by zero-valent iron-supported biochar, characterized in that, Includes the following steps: S1. After cleaning and drying the bio-based material, crush and sieve it to obtain bio-based fine powder; S2. Ferric chloride, bio-based fine powder, and water are mixed and stirred in a mass ratio of 1:(1-10):(30-50), then dried, ground, and sieved. The mixture is then carbonized in a protective gas at a high temperature of 500-900 ℃ and sieved to obtain zero-valent iron-supported biochar. S3. Add zero-valent iron-supported biochar to the wastewater containing perfluorooctane sulfonic acid (PFOS). The concentration of PFOS is 30 μmol / L-150 μmol / L, and the dosage of zero-valent iron-supported biochar in the wastewater is 0.2 g / L-20 g / L. Stir to allow the zero-valent iron-supported biochar to adsorb PFOS, and obtain the adsorbed zero-valent iron-supported biochar. S4. Add the adsorbed zero-valent iron-loaded biochar to the ball mill jar and ball mill it together with the ball milling media. The ball milling speed is 200-600 rpm and the time is 180-480 min. Perfluorooctane sulfonic acid is degraded.

2. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, The bio-based material is one of the following: corn stalks, bamboo, rice straw, sugarcane bagasse, and wood.

3. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, The drying temperature in step S2 is 95-105 ℃, and the drying time is 48-72 h.

4. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, In steps S1 and S2, the sieve is 90-100 mesh.

5. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, In step S2, the high-temperature carbonization time is 60-120 min, and the heating rate is 5-10 ℃ / min.

6. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, The protective gas mentioned in step S2 is either nitrogen or an inert gas.

7. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, In step S3, the temperature for mixing zero-valent iron-supported biochar with the wastewater containing perfluorooctane sulfonic acid is 20 ℃-38.5℃, and the mixture is stirred at a speed not exceeding 180 rpm for more than 60 min.

8. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, In step S4, the grinding jar and grinding media are made of agate, and the grinding media are small balls with a diameter of 4-10 mm.

9. The method for efficient degradation of perfluorooctane sulfonic acid using zero-valent iron-supported biochar according to claim 1, characterized in that, In step S4, the mass ratio of the adsorbed zero-valent iron-supported biochar material to the ball milling media is 1:(50-100).

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