Gaseous Arsenic Adsorbent and Its Preparation and Application

Abstract

The present invention belongs to the field of gaseous arsenic adsorption, and specifically relates to a preparation method of a gaseous arsenic adsorbent. First, iron sulfide and metal M oxide are ultrasonically treated to obtain an ultrasonically treated material, and then the ultrasonically treated material is ball-milled to obtain the adsorbent; the metal M is at least one of Al, Ca, Cu, and Mn. The present invention also includes the material prepared by the above preparation method and its application in gaseous arsenic adsorption. The material prepared by the process of the present invention has excellent adsorption effect on gaseous arsenic.

Description

Technical Field

[0001] The present invention relates to the field of arsenic removal, and particularly to the field of gaseous arsenic removal. Background Art

[0002] The heavy metal emissions in industrial flue gas have caused irreversible impacts on the atmospheric environment and endanger human health. Arsenic-containing compounds are one of the most harmful substances in the current environment. Once they enter the human body, it is very difficult to remove them. Arsenic can enter the human body through the respiratory tract, skin, digestive tract, etc., harm human cells, and cause various diseases, such as toxic neurasthenia, polyneuritis, skin cancer, etc. Currently, the arsenic discharged into the environment from industrial production is about 195.0 t / year. The arsenic emissions in the flue gas of coal-fired power plants, non-ferrous metals, inorganic chemicals, etc. have gradually attracted attention. Reducing arsenic emissions in flue gas is of great significance for achieving ultra-low emissions of industrial flue gas.

[0003] Currently, there is no conclusion on the arsenic form in flue gas. There are many forms of arsenic (As, AsO, As2O3, As2O5, etc.). Along the flue gas flow, as the temperature decreases, the form of arsenic will change. Most experimental conclusions believe that the main form of arsenic in the flue gas at the boiler outlet is As2O3. The thermodynamic properties of As2O3 are relatively stable, not easily dissociated, and compared with the toxicity of many arsenic compounds, trivalent arsenic has the strongest toxicity. Therefore, the removal of As2O3 is one of the greatest challenges in the control of industrial flue gas arsenic emissions.

[0004] The control of arsenic pollution in coal-fired flue gas can be mainly divided into three aspects: before combustion, during combustion, and after combustion. Pretreatment before combustion mainly refers to coal processing technologies, including mainly coal washing technology. Arsenic removal during combustion mainly refers to using arsenic-fixing agents to inhibit arsenic emissions, that is, adding arsenic-fixing agents to coal to fix arsenic in the coal combustion residue, and then removing it with the residue treatment device. Arsenic removal after combustion is the main method of arsenic control technology, mainly including the adsorbent method and using existing pollution control equipment and technologies for arsenic removal. The adsorbent method is a relatively mature flue gas arsenic removal process today. Due to its well-developed pore structure, the adsorbent can provide a large surface area for the condensation of gaseous arsenic. It has the advantages of large adsorption capacity and high arsenic removal efficiency, and has broad application prospects in removing arsenic-containing compounds in flue gas. However, currently, the development of high-performance gaseous arsenic adsorbents at low temperatures of 100 - 300°C for industrial flue gas is in the initial stage and there is little development. Summary of the Invention

[0005] Aiming at the problem of unsatisfactory arsenic removal performance of gaseous arsenic adsorption materials at low temperatures, the first object of the present invention is to provide a preparation method of a gaseous arsenic adsorbent, aiming to prepare a gaseous arsenic adsorption material with excellent adsorption capacity and stability.

[0006] The second object of the present invention is to provide the gaseous arsenic adsorbent prepared by the preparation method and its application in removing gaseous arsenic.

[0007] Aiming at the problem that the low-temperature adsorption capacity of the adsorption material for gaseous arsenic is not ideal, the present invention provides the following solutions:

[0008] A preparation method of a gaseous arsenic adsorbent, which comprises ultrasonically treating iron sulfide and metal M oxide in advance to obtain an ultrasonically treated material, and then ball-milling the ultrasonically treated material to obtain the adsorbent.

[0009] The metal M is at least one of Al, Ca, Cu, and Mn.

[0010] The present invention innovatively ultrasonically treats iron sulfide and metal M oxide in advance, and then performs ball milling. In this way, based on the combination of components, the combined process of ultrasonic treatment first and then ball milling, and the sequence combination, synergy can be achieved, and a new material with brand-new physical and chemical structural characteristics can be obtained. More importantly, the material is innovatively used for the adsorption of gaseous arsenic, and it can exhibit excellent low-temperature gaseous arsenic adsorption capacity and stability.

[0011] In the present invention, the combined synergy of the combined material of sulfide and metal M oxide and the combined process of ultrasonic treatment first and then ball milling is the key to improving the adsorption performance of the prepared material for gaseous arsenic.

[0012] The iron sulfide can be a commercial product or prepared based on known methods. In the present invention, the iron sulfide is obtained by a precipitation reaction of an iron source and a water-soluble sulfide.

[0013] In the present invention, the iron source is a water-soluble salt of Fe(III), preferably at least one of iron nitrate, iron acetate, iron sulfate, and iron chloride.

[0014] In the present invention, the water-soluble sulfide is a water-soluble salt capable of ionizing S 2- and is preferably at least one of sodium sulfide, sodium hydrosulfide, potassium sulfide, and ammonium sulfide.

[0015] In the present invention, the water-soluble sulfide is 1 to 1.5 times the theoretical molar amount for completely precipitating Fe in the iron source.

[0016] In the present invention, the solvent for the precipitation reaction is water or a mixed solvent of water-organic solvent.

[0017] In the present invention, the organic solvent is a solvent miscible with water.

[0018] In the present invention, the iron sulfide is preferably FeS.

[0019] In the present invention, the oxide of the metal M can be a commercial product or prepared based on known methods.

[0020] In the present invention, the metal M oxide is at least one of CaO, MnO2, and γ-Al2O3.

[0021] In the present invention, the molar ratio of Fe / M in the iron sulfide and the metal M oxide is 1:1 to 4, and considering the effect and cost, it can be further preferably 1:1.5 to 3.

[0022] In the present invention, the solvent in the ultrasonic stage is water or a mixed solvent of water-organic solvent;

[0023] Preferably, the organic solvent is a solvent that can be miscible with water.

[0024] In the present invention, considering the simplicity of the treatment process, the metal M oxide can be directly added to the precipitation reaction solution of the iron sulfide, and then the ultrasonic treatment is carried out.

[0025] Preferably, in the solvent, the water content is not less than 50 v%.

[0026] In the present invention, the temperature in the ultrasonic treatment stage is 20 to 70 °C, and considering the simplicity of the treatment and cost, it can be further room temperature such as 25 to 35 °C;

[0027] Preferably, the power in the ultrasonic treatment stage is 100 W to 300 W;

[0028] Preferably, the ultrasonic treatment time is 2 h to 4 h.

[0029] In the present invention, the rotation speed in the ball milling stage is 200 to 600 rpm / min, and the revolution speed is 100 - 300 rpm / min;

[0030] Preferably, the mass ratio of the balls to the material in the ball milling stage is 10:1 to 20:1;

[0031] Preferably, the ball milling time is 20 to 40 min.

[0032] The present invention also provides a gaseous arsenic adsorbent prepared by the above-mentioned preparation method.

[0033] In the present invention, the above-mentioned preparation method can endow the product with special physical and chemical characteristics and can prepare a material with new characteristics. Moreover, the research of the present invention also finds that innovatively using the material prepared by the method for the desorption of gaseous arsenic can unexpectedly exhibit excellent adsorption capacity and stability.

[0034] The present invention also provides an application of the gaseous arsenic adsorbent prepared by the above-mentioned preparation method. As an adsorption material, it is used to adsorb and reduce the arsenic content in the arsenic-containing gas.

[0035] In the present invention, the arsenic-containing gas is a gas containing at least one of As2O3 and AsH3;

[0036] In the present invention, the temperature in the adsorption stage is 100 - 300 °C, and can be further reduced to 140 - 160 °C;

[0037] In the present invention, there is no particular requirement for the adsorption method, and for example, it can be a fixed bed type.

[0038] Beneficial effects

[0039] In the present invention, iron sulfide and metal M oxide are innovatively pre-treated by ultrasonic treatment and then ball-milled. In this way, based on the combination of composition, the combined process and sequence of ultrasonic treatment first and then ball-milling can achieve synergy, and a new material with brand-new physical and chemical structure characteristics can be obtained. More importantly, this material is innovatively used for the adsorption of gaseous arsenic, and it can exhibit excellent low-temperature gaseous arsenic adsorption capacity and stability.

[0040] In the method of the present invention, the adsorption material has excellent arsenic adsorption and arsenic fixation stability, and its low-temperature arsenic removal efficiency at 150 °C is as high as over 70%.

[0041] Combining the above advantages, the adsorbent can efficiently oxidize and adsorb and fix the gaseous arsenic in the flue gas, greatly reducing the content of gaseous arsenic in the flue gas. The preparation process of the gaseous arsenic adsorbent of the present invention is relatively simple, has a high capture efficiency for gaseous arsenic in the flue gas, and a large adsorption capacity. The preparation method of the gaseous arsenic adsorbent of the present invention has important significance and potential industrial application prospects for promoting the research and development and engineering application of low-cost, high-efficiency, and environmentally friendly arsenic removal adsorption materials for industrial flue gas in China. Description of the drawings

[0042] Figure 1 XRD patterns of the materials prepared in Example 1 and Comparative Examples 1, 4, and 5; Specific embodiments

[0043] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention. The specific preparation conditions and results described in the examples are only for explaining the present invention and do not limit the present invention described in the claims in any way. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and equivalent replacements can be made. These technical solutions obtained by improving and equivalently replacing the claims of the present invention all fall within the protection scope of the present invention.

[0044] The high-performance gaseous arsenic adsorbent prepared by the present invention is evaluated for its arsenic removal performance on a fixed-bed flue gas arsenic adsorption performance test device. The test device for this adsorption performance mainly consists of a gas distribution and flow control system, an As2O3 generation device, a flue gas preheating and mixing system, a fixed-bed adsorption reaction device, and a tail gas treatment device. The gas flow rates of each flue gas component are accurately and stably controlled by mass flow meters (Beijing Sevenstar Flow Co., Ltd.). Gaseous As2O3 is generated by the reaction of AsH3 produced by an arsenic generator (Valco Instruments Co., Ltd., USA) with O2 in the preheating device (at 700 °C). The concentration of As2O3 in the flue gas is determined by the permeability of the AsH3 generator and the total flow rate of the flue gas. The AsH3 permeability is stable at 200 ng / min, and the generated concentration of As2O3 is 253.81 μg / m 3 . After the experiment, the adsorbent is digested, and the arsenic content is determined by an inductively coupled plasma optical emission spectrometer (ICP-OES).

[0045] In the implementation case of the present invention, the reaction conditions for arsenic removal by the adsorbent are as follows: the total flow rate of the simulated flue gas is 1 L / min, in which the volume content of O2 is 5%, the volume content of CO2 is 12%, and N2 is used as the balance gas; the adsorption temperature is set at 150 °C, and the time for removing As2O3 is selected as 480 min; the tail gas at the outlet of the fixed bed is successively absorbed by a mixed solution of 5% HNO3 / 10% H2O2 and activated carbon.

[0046] The removal ability of the adsorbent for As2O3 is comprehensively evaluated by the adsorption capacity and the removal efficiency, both of which are based on an adsorption time of 480 min. The adsorption capacity is the mass of As2O3 adsorbed per unit mass of the adsorbent, μg / g, and the removal efficiency is the ratio of the total mass of As2O3 adsorbed by the adsorbent to the total mass of As2O3 entering the fixed bed during the experiment, as shown in the following formula.

[0047]

[0048] In the formula: η As represents the arsenic removal efficiency, %; m is the mass of the adsorbent, g; S As represents the arsenic adsorption capacity, μg / g; C As represents the arsenic generation concentration, μg / min; t represents the arsenic removal time of the adsorbent, min. During the adsorption stage, the dosages of each adsorbent are the same, and the particle size is controlled between 200 - 300 μm based on the screening method.

[0049] An example of the preparation of a typical gaseous arsenic adsorbent of the present invention is as follows:

[0050] (1) Weigh a certain amount of iron nitrate (Fe(NO3)3) and sodium sulfide (Na2S), prepare a solution and mix and stir to obtain iron sulfide (Fe xS y )。

[0051] (2) Weigh a certain amount of metal oxide (MeO z ), and add it to (1).

[0052] (3) Ultrasonically treat and age the sample obtained in (2).

[0053] (4) Separate the solid and liquid of the sample obtained in (3), wash the solid, and dry it with hot air.

[0054] (5) Prepare the particulate matter obtained in (4) into a separable high-performance modified metal oxide gaseous arsenic adsorbent by mechanical ball milling.

[0055] In the present invention, in the ultrasonic treatment stage, the temperature of the ultrasonic treatment stage is 20 - 70 °C; the power of the ultrasonic treatment stage is 100 W - 300 W; the time of ultrasonic treatment is 2 h - 4 h. Under these conditions, similar ultrasonic treatment effects can be obtained. Considering the treatment cost, the temperature can be room temperature, such as between 25 - 35 °C, the power can be 200 - 250 W, and the time can be 2 - 2.5 h.

[0056] In the present invention, the parameters of ball milling can be controlled at: rotation: 200 - 600 rpm / min, revolution: 100 - 300 rpm / min; the mass ratio of balls to materials in the ball milling stage is 10:1 - 20:1; the ball milling time is 20 - 40 min; within these parameters, similar technical effects can be obtained. Considering the treatment efficiency and cost, further, rotation: 300 - 400 rpm / min, revolution: 200 - 250 rpm / min; the mass ratio of balls to materials in the ball milling stage is 15:1 - 20:1.

[0057] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. The raw materials can be obtained from public commercial channels without special instructions. The methods are conventional methods without special instructions.

[0058] Example 1:

[0059] Step (1):

[0060] Weigh 0.05 mol of ferric nitrate (Fe(NO3)3) and 0.05 mol of sodium sulfide (Na2S), add them to 250 ml of deionized water and mix and stir for 0.5 h to obtain an iron sulfide reaction solution. Weigh 0.15 mol of calcium oxide (CaO), place it into the solution obtained above for composite treatment, and assist in the composite stage under ultrasonic conditions. Set the water temperature of the ultrasonic oscillator to 30 °C, the ultrasonic power to 200 W, and take it out after 3 h of ultrasonic treatment. After ultrasonic treatment, the obtained Fe x S yAfter filtration, separation, and washing, the / CaO solid particles were placed in a hot air drying oven for preliminary drying at a drying temperature of 110 °C for 12 h.

[0061] Step (2):

[0062] Finally, the dried sample was placed in a ball mill for mechanical ball milling. The parameters were set as follows: rotation speed of 300 rpm / min, revolution speed of 200 rpm / min, ball milling time of 30 min, and the ratio of ball milling medium to material of 15:1.

[0063] The obtained sample was designated as B1.

[0064] Example 2:

[0065] Step (1):

[0066] Weigh 0.05 mol of iron nitrate (Fe(NO3)3) and 0.05 mol of sodium sulfide (Na2S), add them to 250 ml of deionized water, and mix and stir for 0.5 h to obtain an iron sulfide reaction solution. Weigh 0.075 mol of alumina (γ-Al2O3), place it into the above-obtained solution for composite treatment, and the composite stage was assisted by ultrasound. Set the water temperature of the ultrasonic oscillator to 30 °C, the ultrasonic power to 200 W, and take it out after 3 h of ultrasound. After ultrasound, the obtained Fe x S y / γ-Al2O3 solid particles were filtered, separated, washed, and then placed in a hot air drying oven for preliminary drying at a drying temperature of 110 °C for 12 h.

[0067] Step (2):

[0068] Finally, the dried sample was placed in a ball mill for mechanical ball milling. The parameters were set as follows: rotation speed of 300 rpm / min, revolution speed of 200 rpm / min, ball milling time of 30 min, and the ratio of ball milling medium to material of 15:1.

[0069] The obtained sample was designated as B2.

[0070] Example 3:

[0071] Weigh 0.05 mol of iron nitrate (Fe(NO3)3) and 0.05 mol of sodium sulfide (Na2S), add them to 250 ml of deionized water, and mix and stir for 0.5 h to obtain an iron sulfide reaction solution. Weigh 0.15 mol of manganese dioxide (MnO2), place it into the above-obtained solution for composite treatment, and the composite stage was assisted by ultrasound. Set the water temperature of the ultrasonic oscillator to 30 °C, the ultrasonic power to 200 W, and take it out after 3 h of ultrasound. After ultrasound, the obtained Fe x S yThe / MnO2 solid particles were filtered, separated, washed and then placed in a hot air drying oven for preliminary drying at a drying temperature of 110°C for 12 hours. Finally, the dried sample was placed in a ball mill for mechanical ball milling with the parameter settings as follows: rotation speed of 300 rpm / min for self-rotation, 200 rpm / min for revolution, ball milling time of 30 minutes, and the ratio of ball milling medium to material of 15:1.

[0072] The obtained sample was designated as B3.

[0073] Example 4

[0074] Compared with Example 1, the only difference is that the temperature during the ultrasonic stage is 35°C, the power is 250 W, and the time is 2.5 h;

[0075] And during the ball milling stage, the rotation speed for self-rotation is 400 rpm / min, the revolution speed is 250 rpm / min, the ball milling time is 20 minutes, and the ratio of ball milling medium to material is 20:1. The obtained sample was designated as B4.

[0076] Comparative Example 1:

[0077] Compared with Example 1, the only difference is that calcium oxide (CaO, labeled as A1) recorded therein was used as the adsorbent.

[0078] Comparative Example 2:

[0079] Compared with Example 2, the only difference is that alumina (γ-Al2O3, labeled as A2) recorded therein was used as the adsorbent.

[0080] Comparative Example 3:

[0081] Compared with Example 3, the only difference is that manganese dioxide (MnO2, labeled as A3) recorded therein was used as the adsorbent.

[0082] Comparative Example 4:

[0083] Compared with Example 1, the only difference is that calcium oxide was not added, and other operations and parameters were the same as those in Example 1. The prepared material was iron sulfide (Fe x S y , labeled as A4) as the adsorption material.

[0084] Comparative Example 5:

[0085] Compared with Example 1, the only difference is that only ultrasonic treatment was carried out without ball milling treatment, and the ultrasonic time in Step 1 was 3.5 h. Other operations and parameters were the same as those in Example 1.

[0086] The obtained sample was designated as A5.

[0087] Comparative Example 6:

[0088] Compared with Example 1, the only difference is that ultrasonic treatment was not performed in advance, and the difference step is that the composite treatment stage in Step 1 was not carried out under ultrasonic assistance: other operations and processes are the same as in Example 1.

[0089] The obtained sample is denoted as A6.

[0090] Comparative Example 7:

[0091] Compared with Example 1, the only difference is that ball milling treatment was carried out first and then ultrasonic treatment. The different steps are as follows: in the composite stage of Step 1, wet ball milling was carried out for 30 min under the ball milling conditions of Example 1, and then ultrasonic treatment was carried out for 3 h under the ultrasonic conditions of Step 1 of Example 1, and then dried to obtain the adsorption material.

[0092] The obtained sample is labeled as A7.

[0093] Test Examples 1-11:

[0094] Take 200 mg of the above samples A1, A2, A3, A4, A5, A6, A7, B1, B2, B3, B4 and place them on a fixed-bed reactor for gas-phase arsenic adsorption experiments. The concentration of As2O3 is 253.85 μg / m 3 , the simulated flue gas flow rate is 1 L / min, the adsorption time is 480 min, and the adsorption temperature is set at 150 °C. After the experiment, digest the adsorbed samples A1, A2, A3, A4, A5, A6, A7, B1, B2, B3, B4 (the dosage of the adsorbent is the same in the adsorption stage), and determine the arsenic content by inductively coupled plasma optical emission spectrometer (ICP-OES), and finally obtain the adsorption efficiency of the adsorbent. The test results are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] It can be seen through Figure 1 that by using the method of the present invention, the phase transformation of the material is realized, and it is innovatively used for the adsorption of gaseous arsenic, and better effects can be obtained. For example, it can be seen from the test examples in Table 1 that the metal oxide and iron sulfide before treatment (Fe x S y)The arsenic adsorption efficiency at 150 °C is all below 60%. After being treated by the preparation method of the separable high-performance gaseous arsenic adsorbent proposed by the present invention, the adsorption efficiency of gaseous arsenic at 150 °C is as high as over 70%, showing a significant improvement compared with the adsorption efficiency of the metal oxide adsorbent before treatment. After attracting the adsorbent after adsorption in the examples with a magnet, it is observed that most of the adsorbents are attracted, achieving the purpose of efficient separation. It can be seen that the preparation method of the separable high-performance gaseous arsenic adsorbent proposed by the present invention can significantly improve the adsorption efficiency of gaseous arsenic and has the application prospect of efficiently removing gaseous arsenic from industrial flue gas at 100 - 300 °C.

[0099] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple combinatorial modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications should be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. Application of a gaseous arsenic adsorbent, characterized in that, It is used as an adsorbent material to adsorb and reduce the arsenic content in arsenic-containing gases; The preparation method of the gaseous arsenic adsorbent is as follows: First, ultrasonic treatment is performed on iron sulfide and metal M oxide to obtain an ultrasonically treated material, and then the ultrasonically treated material is ball-milled to obtain the product; The metal M is at least one of Al, Ca, Cu, and Mn.

2. The application according to claim 1, characterized in that The iron sulfide is obtained by a precipitation reaction of an iron source and a water-soluble sulfide.

3. The application according to claim 2, wherein The iron source is a water-soluble salt of Fe(III).

4. The application according to claim 3, wherein, The iron source is at least one of iron nitrate, iron acetate, iron sulfate, and iron chloride.

5. The application according to claim 2, characterized in that The water-soluble sulfide is a water-soluble salt that can ionize S 2- .

6. The application according to claim 5, characterized in that, The water-soluble sulfide is at least one of sodium sulfide, sodium hydrosulfide, potassium sulfide, and ammonium sulfide.

7. The application according to claim 2, wherein The water-soluble sulfide is 1 to 1.5 times the theoretical molar amount for completely precipitating Fe in the iron source.

8. The application according to claim 2, characterized in that, The solvent for the precipitation reaction is water or a mixed solvent of water-organic solvent.

9. The application according to claim 8, wherein The organic solvent is a solvent miscible with water.

10. The application according to claim 1, characterized in that The metal M oxide is at least one of CaO, MnO2, and γ-Al2O3.

11. The application according to claim 1, characterized in that, The molar ratio of Fe / M in the iron sulfide and the metal M oxide is 1:1 to 4.

12. The application according to claim 1, characterized in that The solvent in the ultrasonic stage is water or a mixed solvent of water-organic solvent.

13. The application according to claim 12, characterized in that, The organic solvent is a solvent miscible with water.

14. The application according to claim 12, wherein In the mixed solvent, the water content is not less than 50 v%.

15. The application according to claim 1, characterized in that The temperature in the ultrasonic treatment stage is 20 to 70 °C.

16. The application according to claim 1, characterized in that The power in the ultrasonic treatment stage is 100 W to 300 W.

17. The application according to claim 1, characterized in that, The time of ultrasonic treatment is 2 h to 4 h.

18. The application according to claim 1, wherein Rotation speed in the ball-milling stage: 200 to 600 rpm / min, revolution speed: 100 - 300 rpm / min.

19. The application according to claim 1, characterized in that, The mass ratio of balls to materials in the ball-milling stage is 10:1 to 20:

1.

20. The application according to claim 1, characterized in that, The ball-milling time is 20 to 40 min.

21. The application according to any one of claims 1 to 20, characterized in that, The arsenic-containing gas is a gas containing at least one of As2O3 and AsH3.

22. The application according to claim 21, wherein, The temperature in the adsorption stage is 100 to 300 °C.

23. The application according to claim 1, wherein The adsorption method is a fixed-bed type.

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