A method for catalytic reduction of arsenic pollutants in water bodies by vinasse biochar

Abstract

This invention discloses a method for removing arsenic pollutants from water bodies by catalytic reduction using distiller's grains biochar, comprising the following steps: mixing distiller's grains biochar, thiourea, and arsenic-containing water, and carrying out a catalytic reduction reaction under anaerobic stirring conditions to remove arsenic pollutants from the water body; wherein the mass ratio of the distiller's grains biochar to the arsenic pollutants in the water body is 10:1 to 6000:1, and the molar ratio of the thiourea to arsenic is 50:1 to 650:1. This invention applies distiller's grains biochar to activate thiourea to reduce and remove arsenic pollutants from water bodies. The distiller's grains biochar, with its well-developed pores and surface functional groups, simultaneously adsorbs and enriches arsenic species and activates thiourea. The strongly reducing active species produced by thiourea can efficiently reduce highly toxic soluble arsenic to a less toxic or easily separable form, fundamentally solving the technical problem that existing water arsenic removal technologies cannot simultaneously achieve mild, neutral reaction conditions, no secondary pollution, and preservation of phosphorus resources.

Description

Technical Field

[0001] This invention relates to a method for the catalytic reduction of arsenic pollutants in water by biochar from distiller's grains, belonging to the field of catalytic reduction treatment of arsenic-containing water pollutants. Background Technology

[0003] Traditional phosphorus chemical wastewater treatment primarily employs end-of-pipe approaches such as chemical precipitation or biological methods. The fundamental flaw lies in misclassifying valuable phosphorus resources, which should be recycled as nutrients for life, as pollutants requiring removal. This results in the storage of phosphorus as low-value chemical or biological sludge, causing not only a severe waste of this non-renewable strategic resource but also secondary pollution. Therefore, developing efficient technologies capable of selectively removing multiple pollutants such as fluorides and arsenic while recovering phosphorus resources is crucial. Currently, methods for removing asphalt (As) from water bodies include physical, chemical, and biological approaches. Among the many selective As removal technologies, adsorption and chemical precipitation using metals such as zirconium, manganese, titanium, nickel, bismuth, and iron, as well as their metal oxides, show great promise due to their excellent selective adsorption of As and resistance to interference from coexisting ions. However, the treatment of metals and their oxides is costly, has limited adsorption capacity, and is prone to secondary pollution. Therefore, selecting low-cost, readily available, and regenerable materials as adsorbents is the preferred technological approach.

[0004] Distillers' grains are a large-scale biomass byproduct generated in my country's brewing industry. As a typical organic waste, if not properly treated (such as by random dumping or landfilling), it not only occupies land resources but may also generate leachate and odorous gases during degradation, causing secondary pollution to the surrounding environment. However, if biochar is directly prepared from raw distillers' grains and used to adsorb arsenic pollutants in water, the resulting material usually suffers from problems such as limited specific surface area, underdeveloped pore structure, and simple surface functional groups, resulting in low adsorption capacity for arsenic, insufficient selectivity, and poor cycle stability. Thiourea dioxide (TDO) is a green and inexpensive reducing agent that can effectively reduce As(III) and As(V) under alkaline conditions. Its core mechanism (Equation 1) is generally considered to be the active reducing species (such as sulfonyl SO2) produced by the decomposition of TDO. 2- Arsenic (and its derivatives) is reduced to elemental arsenic [As(0)].

[0005] H2N(HN=)CSO2H (H2N)2CO + SO2 2- + H2O (1) Although chemical reduction methods, represented by thiourea dioxide (TDO), can reduce highly toxic As(III) and As(V) to elemental arsenic, this method itself has significant limitations as a reducing agent. Existing technologies using TDO for arsenic removal (such as CN121134832A) have significant limitations: this process must be carried out under high temperature and strong alkaline conditions, resulting in high energy consumption, complex processes, and high operating costs. Furthermore, the low utilization rate of TDO limits its application in practical water treatment. In addition, technologies using biochar as an adsorbent to treat arsenic (such as CN118767869A and LU600070B1) can be carried out at room temperature, but only achieve phase transfer of arsenic. After adsorption saturation, a large amount of arsenic-containing solid waste is generated, requiring secondary treatment and posing environmental risks. Removal technologies based on metal oxide modified biochar (such as CN114307944A, CN111111615B, CN113952926B) can convert arsenic into its form, but the introduction of metals will lead to the consumption of a large amount of phosphate during the reaction process and will also introduce metal elements, which can easily cause secondary pollution.

[0006] Based on the above, existing water arsenic pollution removal technologies cannot simultaneously meet the comprehensive application requirements of efficient arsenic removal, mild reaction conditions, no secondary pollution, and preservation of phosphorus resources in the water. Furthermore, existing biochar-based arsenic removal materials are mostly prepared from raw materials such as rice straw and sawdust, failing to utilize the large-scale by-product of the brewing industry, which produces over ten million tons annually, in a high-value manner. The indiscriminate storage or landfilling of this by-product further occupies land resources and generates secondary environmental pollution problems such as leachate and odors. Summary of the Invention

[0007] (a) Purpose of the invention The purpose of this invention is to overcome the shortcomings of existing arsenic removal technologies for water bodies, such as the inability to simultaneously meet the requirements of mild reaction conditions, no secondary pollution, and difficulty in retaining phosphorus resources. Therefore, this invention provides a method for the catalytic reduction of thiourea dioxide using biochar, which can efficiently remove arsenic pollutants from water bodies under mild, neutral conditions with low cost and no secondary pollution, while simultaneously retaining phosphorus resources in the water.

[0008] (II) Technical Solution A method for removing arsenic pollutants from water by catalytic reduction of distillers' grains biochar includes the following steps: mixing distillers' grains biochar, thiourea and arsenic-containing water, and carrying out a catalytic reduction reaction under anaerobic stirring conditions to complete the removal of arsenic pollutants from the water; wherein the mass ratio of the distillers' grains biochar to the arsenic pollutants in the water is 10:1 to 6000:1, and the molar ratio of the thiourea to arsenic is 50:1 to 650:1.

[0009] The method for catalytic reduction removal of arsenic pollutants from water using distiller's grains biochar according to claim 1 is characterized in that the preparation method of the distiller's grains biochar is as follows: S1. After sorting and removing impurities from the lees, the lees are sieved to obtain pretreated lees raw material; S2. The pretreated distiller's grains raw material is subjected to pyrolysis treatment to obtain pyrolysis products; S3. The pyrolysis product is ball-milled and then dried to obtain biochar from distiller's grains for catalytic reduction and arsenic removal.

[0010] In one example, in step S2, the heating rate of the pyrolysis process is 2.5 ℃ / min to 7.5 ℃ / min, the pyrolysis temperature is 400 ℃ to 900 ℃, and the pyrolysis time is 0.5 h to 2 h.

[0011] In one example, the pyrolysis process is carried out in a tubular furnace under a nitrogen protective atmosphere.

[0012] In one example, in step S3, the ball milling speed is 100 r / min to 250 r / min, and the ball milling time is 8 h to 12 h.

[0013] In one example, the distillery biochar has a porous graphitized carbon structure with a surface rich in oxygen-containing functional groups; the average pore radius of the distillery biochar is 25 nm to 30 nm, and the oxygen-containing functional groups on the surface include hydroxyl and carboxyl groups.

[0014] In one example, the thiourea is selected from at least one of thiourea dioxide, dibutylthiourea, or diphenylthiourea.

[0015] In one example, the pH value of the arsenic-containing water body is 5 to 13.

[0016] In one example, the anaerobic conditions are achieved by introducing nitrogen gas into the reaction system; the temperature of the catalytic reduction reaction is 20 ℃ to 85 ℃, the stirring speed is 100 rpm to 250 rpm, and the reaction time is 45 min to 180 min.

[0017] (III) Beneficial Effects This invention fundamentally solves the technical problem that existing water arsenic removal technologies cannot simultaneously achieve mild and neutral reaction conditions, no secondary pollution, and preservation of phosphorus resources: First, this invention innovatively applies distillers' grains biochar to activate thiourea for the reduction and removal of arsenic pollutants in water. Its mechanism of action lies in the fact that distillers' grains biochar, with its well-developed pores and surface functional groups, simultaneously adsorbs and enriches arsenic species and activates thiourea. The strongly reducing active species generated by thiourea (such as sulfonyl radicals) can efficiently reduce highly toxic soluble arsenic (such as As(III) and As(V)) to less toxic or easily separable forms (such as elemental arsenic). This system overcomes the technical bottleneck of traditional thiourea dioxide activation, which requires high temperatures (80 ℃) and strong alkaline conditions (pH=13). Using distillers' grains biochar as an activator, this invention maintains a high arsenic removal rate within a wide pH range of 5-13 and at room temperature (25 ℃) (for example, for simulated wastewater containing 5 mg / L As(V), the reduction and removal rate can reach 90% within 90 minutes). Therefore, this method combines the advantages of simple process, low reaction energy consumption, and efficient arsenic reduction under neutral conditions.

[0018] Secondly, this invention uses widely available distiller's grains as a precursor and, through optimized pyrolysis and subsequent ball milling processes, successfully prepares biochar with a high specific surface area, abundant hierarchical pores (especially mesoporous), and partially graphitized structure. This preparation method fully utilizes the loose texture and high cellulose content of distiller's grains. The pyrolysis process effectively inherits its natural framework, while the ball milling further modifies and expands the specific surface area and pore structure, while introducing numerous defect sites and oxygen-containing functional groups. Compared to biochar made from other materials (such as sawdust and rice straw), the distiller's grains biochar obtained by this invention exhibits superior performance in terms of specific surface area, oxygen-containing functional groups, and degree of graphitization, thus exposing more active sites. These characteristics enable it to demonstrate excellent activation ability for thiourea reducing agents, efficiently driving the catalytic reduction and fixation of arsenic pollutants in water.

[0019] Third, the biochar prepared by this invention does not contain harmful metal components, does not pose a risk of secondary pollution caused by metal leaching, and has no problem of coordination between metal active sites and phosphate ions. It consumes very little phosphate in water and the phosphorus retention rate after reaction can reach more than 90%, thus achieving effective retention of phosphorus resources in the arsenic removal process.

[0020] Fourth, this invention uses distiller's grains, a major byproduct of the brewing industry, as raw material, realizing the high-value utilization of waste biomass, avoiding environmental problems caused by the random accumulation of distiller's grains, meeting the requirements of circular economy and carbon emission reduction, and the raw material cost is extremely low, which greatly reduces the preparation cost of arsenic removal materials. Attached Figure Description

[0021] Figure 1 SEM-EDS image of biochar from distiller's grains; Figure 2 The removal effect of As(V) under different conditions; Figure 3 The removal effect of As(V) with different amounts of biochar. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] To address the shortcomings of existing water arsenic pollution removal technologies in simultaneously meeting the comprehensive application requirements of efficient arsenic removal, mild reaction conditions, no secondary pollution, and retention of phosphorus resources in the water, this invention utilizes waste distiller's grains as raw material and prepares a highly catalytically active biochar from distiller's grains using a pyrolysis-coupled ball milling process. This material can efficiently activate thiourea reducing agents under mild conditions of room temperature and near neutrality, reducing soluble trivalent and pentavalent arsenic in the water to easily separable, low-toxicity elemental arsenic. Furthermore, because the material itself does not contain metal components, it will not undergo coordination reactions with phosphate ions in the water, achieving a high retention rate of phosphorus resources during the arsenic removal process, fundamentally solving multiple deficiencies of existing technologies.

[0024] All raw materials and instruments used in the following examples are commercially available. Unless otherwise specified, the data obtained in the following examples are the average values ​​of three or more repeated experiments.

[0025] This preparation method uses different materials (distillers' grains, rice straw, and sawdust) as raw materials, and prepares the product through pyrolysis and ball milling (mechanical modification), including the following steps: (1) First, manually sort the raw materials (remove impurities, and crush the rice straw first), sieve (pass through 30-100 mesh), and then use the remaining materials for later use.

[0026] (2) The raw materials that were manually sorted (removed impurities) and screened in step (1) were placed in a tube furnace and heated to 600 ℃ at a rate of 2.5 ℃ / min under a nitrogen protective atmosphere, and then pyrolyzed at this temperature for 2 h.

[0027] (3) The pyrolyzed powder from step (2) was placed in a planetary ball mill and continuously ball-milled at a stirring rate of 200 r / min for 12 h. After ball milling, the powder was first passed through a 100-mesh sieve and then dried in a constant temperature drying oven at 60 ℃ to obtain the biochar corresponding to each material.

[0028] Scanning electron microscopy (SEM-EDS) was performed on the biochar prepared by the above method. Figure 1 ) Observation. By Figure 1 It is evident that the biochar from distiller's grains possesses a three-dimensional, loose, sheet-like structure and a wrinkled, coiled surface. This biochar exhibits a graphitized porous structure with noticeable wrinkles on its surface. These characteristics inherit the loose, natural structure of distiller's grains, indicating that this method can successfully prepare porous biochar materials. Furthermore, the material surface primarily contains C, O, and Si elements, fundamentally avoiding the risk of secondary pollution from metal leaching.

[0029] The physicochemical properties of the different biochars prepared above were tested, and the results are shown in Table 1. EC / mS▪cm of distiller's grains biochar -1 It is 0.454, CEC / cmol▪kg -1 The value is 11.696. This is attributed to the presence of oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups in the raw materials themselves. The high oxygen content also suggests that the material surface is rich in oxygen-containing functional groups, which can provide active sites for catalytic reactions. Its pore size is concentrated at approximately 28.44 nm, exhibiting a regular mesoporous structure, which is beneficial for the diffusion and transport of reactants and products.

[0030] Biochar pH <![CDATA[EC / mS▪cm -1 ]]> <![CDATA[CEC / cmol▪kg -1 ]]> Average hole radius at a single point (nm) Pyrolysis temperature (°C) Distillers' grains biochar 9.48 0.454 11.696 28.44 600 Wood biochar 8.06 0.170 47.48 8.75 600 Rice straw biochar 10.32 2.867 12.49 1.05 600 As shown in Table 1, compared with rice straw biochar and sawdust biochar prepared under the same pyrolysis conditions, distiller's grains biochar has the following significant advantages: 1. The average pore radius of the distiller's grains biochar (28.44 nm) is significantly larger than that of sawdust biochar (8.75 nm) and rice straw biochar (1.05 nm), with a higher proportion of mesoporous structure, which can reduce mass transfer resistance and promote the contact between arsenic pollutants and catalytic active sites.

[0031] 2. The pH value of the distiller's grains biochar is 9.48, which is weakly alkaline. Compared with the strongly alkaline rice straw biochar (pH=10.32), it reduces the disturbance to the pH of the water body and does not require additional acid-base adjustment; its conductivity (0.454 EC / mS▪cm) -1 The concentration of biochar from rice straw is significantly lower than that from rice straw biochar (2.867 EC / mS▪cm). -1 This can prevent the release of excessive electrolytes into the water.

[0032] Experimental materials: Distillery lees biochar, sawdust biochar, rice straw biochar prepared in Example 1, and thiourea dioxide.

[0033] Test method: Treatment group (distillery waste biochar + thiourea dioxide): Three 50 mL portions of simulated wastewater with an As(V) concentration of 15 mg / L and a pH of 8 were taken and placed in three 60 mL sealed glass bottles. Distillery waste biochar prepared in Example 1 was added to each bottle, ensuring a total biochar content of 0.15 g in the solution. Simultaneously, thiourea dioxide was added to each bottle, making the molar ratio of thiourea dioxide to As(V) 150:1. The reaction was carried out at 25°C and 150 rpm for 90 min. After the reaction, samples were taken, the biochar was separated from the solution, and the residual As(V) concentration was measured and the removal rate calculated. See Table 2 and... Figure 2 The removal rate of As(V) was 52.06%.

[0034] Control Group 1 (Rice Straw Biochar + Thiourea Dioxide): Three 50 mL portions of simulated wastewater with an As(V) concentration of 15 mg / L were placed in three separate 60 mL sealed glass bottles. Rice straw biochar prepared in Example 1 was added to each bottle, ensuring a total amount of rice straw biochar in the solution of 0.15 g. Simultaneously, thiourea dioxide was added to each bottle, making the molar ratio of thiourea dioxide to As(V) 150:1 (TDO / As(V)). The reaction was carried out at 25 ℃, pH 8, and with shaking at 150 rpm for 90 min. After the reaction, samples were taken, the rice straw biochar was separated from the solution, and the residual As concentration was measured and the removal rate calculated. See Table 2 for details. Figure 2 The removal rate of As(V) was 46.90%.

[0035] Control group 2 (wood biochar + thiourea dioxide): The experimental method was the same as that of control group 1, except that the rice straw biochar was replaced with wood biochar.

[0036] Control group 3 (thiourea dioxide only): 50 mL of 15 mg / L As(V) solution was placed in a 60 mL Erlenmeyer flask, and thiourea dioxide was added to make the molar ratio of thiourea dioxide to As(V) 150:1 (TDO / As(V)). The reaction was carried out at 25℃, pH 8, and shaking at 150 rpm for 90 min. Samples were taken, the residual As(V) concentration was measured, and the removal rate was calculated. After the reaction, samples were taken, the residual As(V) concentration was measured, and the removal rate was calculated. See Table 2 for details. Figure 2 The removal rate of As(V) was 27.10%.

[0037] Control group 4 (distillery lees biochar only): 50 mL of As(V) solution with a concentration of 15 mg / L was placed in a 60 mL Erlenmeyer flask, and the distillery lees biochar prepared in Comparative Example 1 was added, making the amount of distillery lees added to the solution 0.15 g. The reaction was carried out at 25℃, pH 8, and shaking at 150 rpm for 90 min. Samples were taken, the residual As(V) concentration was measured, and the removal rate was calculated. After the reaction, samples were taken, the distillery lees biochar was separated from the solution, the residual As(V) concentration was measured, and the removal rate was calculated. See Table 2 and... Figure 2 The removal rate of As(V) was 10.16%.

[0038] The As(V) removal rates of the treatment group and each control group are shown in Table 2. Figure 2 As shown, the arsenic removal rate of the distiller's grains biochar group was 52.06%, significantly higher than that of the rice straw biochar group (46.90%) and the sawdust biochar group (45.17%). The arsenic removal rate of the control group using thiourea dioxide alone was only 27.10%, and the arsenic removal rate of the control group using distiller's grains biochar alone was only 10.16%. This proves that the distiller's grains biochar of the present invention can effectively activate thiourea and significantly improve the arsenic removal efficiency.

[0039] Table 2. Removal effect of As(V) under different experimental conditions Serial Number Experimental conditions Biochar types pH Temperature (°C) TDO / As(V) molar ratio Reaction time (min) As(V) removal rate (%) A Example 2 Distillers' grains biochar 8 25 150:1 90 52.06% B Comparison 1 Rice straw biochar 8 25 150:1 90 46.90% C Comparison 2 Wood biochar 8 25 150:1 90 45.17% D Comparison 3 none 8 25 150:1 90 27.10% E Compare with 4 Distillers' grains biochar 8 25 0 90 10.16%

[0040] Three 50 mL portions of simulated wastewater with an As(V) concentration of 5 mg / L were taken and placed in three separate 60 mL sealed glass bottles. The biochar prepared in Example 1 was added to each bottle, resulting in biochar concentrations of 0.10 g, 0.20 g, 0.25 g, and 0.30 g, respectively. Thiourea dioxide was also added to each bottle, achieving a thiourea-As(V) molar ratio of 450:1 (TDO / As(V)). The reaction was carried out at 25°C, pH 8, and 150 rpm for 90 min. After the reaction, samples were taken, the biochar was separated from the solution, and the residual As(V) concentration was determined to calculate the removal rate.

[0041] Table 3. Removal effect of As(V) at different biochar addition amounts Biochar addition amount (g) Biochar types pH Temperature (°C) TDO / As(V) molar ratio Reaction time (min) As(V) removal rate (%) 0.10 Distillers' grains biochar 8 25 450:1 90 81.40% 0.20 Distillers' grains biochar 8 25 450:1 90 85.16% 0.25 Distillers' grains biochar 8 25 450:1 90 86.20% 0.30 Distillers' grains biochar 8 25 450:1 90 89.87% Table 3 and Figure 3 This is a graph showing the reduction and degradation effect of thiourea dioxide activated by different dosages of distiller's grains biochar on arsenic in water in Example 3 of the present invention. (Table 3 and...) Figure 3It was found that when the amount of biochar added from distiller's grains was 0.30 g, the reaction was carried out at 25 ℃, pH 8, and 150 rpm for 90 min. The As(V) removal rate was 89.87%. This indicates that the biochar from distiller's grains prepared in this invention can effectively activate thiourea dioxide to achieve the reduction and degradation of arsenic, and the removal effect is significantly enhanced with the increase of biochar dosage.

[0042] Three 50 mL portions of simulated mixed wastewater, each containing 5 mg / L As(V) and 2000 mg / L phosphate, were placed in three separate 60 mL sealed glass bottles. The biochar prepared in Example 1 was added to each bottle to achieve a concentration of 0.25 g of biochar in the solution. Thiourea dioxide was also added to each bottle, resulting in a thiourea-As(V) molar ratio of 450:1 (TDO / As(V)). The reaction was carried out at 25 °C, pH 8, and 150 rpm for 90 min with shaking. After the reaction, samples were taken, the biochar was separated from the solution, and the residual phosphate concentration was measured to calculate the removal rate. The test results showed that the phosphate removal rate was only 5.81%, indicating that most of the phosphate remained in the water.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for removing arsenic pollutants from water by catalytic reduction using biochar from distiller's grains, characterized in that, Includes the following steps: Distillery waste biochar, thiourea, and arsenic-containing water are mixed and subjected to catalytic reduction under anaerobic stirring conditions to remove arsenic pollutants from the water. The mass ratio of the distillery waste biochar to the arsenic pollutants in the water is 10:1 to 6000:1, and the molar ratio of the thiourea to arsenic is 50:1 to 650:

1.

2. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 1, characterized in that, The preparation method of the biochar from distiller's grains is as follows: S1. After sorting and removing impurities from the lees, the lees are sieved to obtain pretreated lees raw material; S2. The pretreated distiller's grains raw material is subjected to pyrolysis treatment to obtain pyrolysis products; S3. The pyrolysis product is ball-milled and then dried to obtain biochar from distiller's grains for catalytic reduction and arsenic removal.

3. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 2, characterized in that, In step S2, the heating rate of the pyrolysis process is 2.5℃ / min to 7.5℃ / min, the pyrolysis temperature is 400℃ to 900℃, and the pyrolysis time is 0.5h to 2h.

4. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 3, characterized in that, The pyrolysis process is carried out in a tubular furnace under a nitrogen protective atmosphere.

5. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 2, characterized in that, In step S3, the ball milling speed is 100 r / min to 250 r / min, and the ball milling time is 8 h to 12 h.

6. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 1, characterized in that, The biochar from the distiller's grains has a porous graphitized carbon structure and its surface is rich in oxygen-containing functional groups; the average pore radius of the biochar from the distiller's grains is 25 nm to 30 nm, and the oxygen-containing functional groups on the surface include hydroxyl and carboxyl groups.

7. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 1, characterized in that, The thiourea is selected from at least one of thiourea dioxide, dibutylthiourea, or diphenylthiourea.

8. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 1, characterized in that, The pH value of the arsenic-containing water body is 5-13.

9. The method for removing arsenic pollutants from water by catalytic reduction of biochar from distiller's grains according to claim 1, characterized in that, The anaerobic conditions are achieved by introducing nitrogen gas into the reaction system; the temperature of the catalytic reduction reaction is 20℃~85℃, the stirring speed is 100rpm~250rpm, and the reaction time is 45min~180min.

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