Modified biochar loaded sulfidized nano zero-valent iron material, and preparation method and application thereof

Abstract

This invention discloses a modified biochar-supported sulfidated nano-zero-valent iron material, its preparation method, and its application, belonging to the field of wastewater treatment technology. The modified biochar-supported sulfidated nano-zero-valent iron material prepared by this invention contains tert-butylphenyl groups on its surface, which can enhance the hydrophobicity of the biochar material surface and improve its adsorption efficiency for bromophenols. At the same time, the sulfidation treatment of the nano-zero-valent iron can form a ferrous sulfide shell on the surface of the nano-zero-valent iron, protecting the nano-zero-valent iron from oxidation and fully utilizing its high reactivity. The material prepared by the method of this invention allows the nano-zero-valent iron to be fully dispersed on the surface of the carrier, effectively avoiding the aggregation of nano-zero-valent iron, fully utilizing its reducing ability, and promoting the degradation of bromophenols.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a modified biochar-supported sulfide nano-zero-valent iron material, its preparation method, and its application. Background Technology

[0002] p-Bromophenol is a typical halogenated phenol compound widely used in organic synthesis, analytical chemistry, and preservatives. Its applications include, but are not limited to, using it as an intermediate in pharmaceutical and dye synthesis, in the preparation of flame retardants or polymer modifiers, as a colorimetric agent for detecting metal ions, and for antibacterial treatment of industrial products. Due to its high solubility and bioaccumulation in organic solvents, coupled with its low biodegradability, p-bromophenol is widely detected in soil and groundwater. However, p-bromophenol also exhibits biotoxicity, and its potential persistent hazards threaten human health.

[0003] Nanomaterials containing zero-valent iron have become one of the most widely studied nanomaterials in wastewater treatment, soil, and groundwater remediation due to their larger specific surface area and potential nanoscale effects. However, nanomaterials containing zero-valent iron suffer from problems such as easy aggregation, easy passivation, and easy non-selective reactions, which reduce their reactivity and mobility, limiting their large-scale application in in-situ remediation.

[0004] Among the proposed strategies for improving the reactivity of nano-zero valent iron, carrier technology and sulfidation treatment are the most promising and widely used methods. For example, patent CN114433020A discloses a method for preparing a composite material with biochar-fixed zero valent iron through co-pyrolysis. This invention involves adding hematite and biomass to deionized water, stirring thoroughly, ultrasonically treating, drying, and then pyrolyzing in a tube furnace to obtain a composite material with biochar-fixed zero valent iron, which is used as an adsorbent for tetracycline. This invention effectively solves the problem of easy agglomeration of nano-zero valent iron by using a carrier treatment method. However, the reduction effect of this method is uncontrollable and limits the full utilization of biomass materials. Patent CN116177710A discloses a method for preparing nano-zero-valent iron supported on sulfide biochar and applying it to the degradation of tetrabromobisphenol A. A composite material composed of biochar and particles supported on it with zero-valent iron as the core and iron sulfide as the shell was prepared, which improved the electronic efficiency and the degradation efficiency of tetrabromobisphenol A. However, the poor hydrophobicity of the composite material surface prevented it from reaching its maximum adsorption performance for pollutants, which limited its further improvement in the degradation efficiency of pollutants. Summary of the Invention

[0005] This invention provides a modified biochar-supported sulfide nano-zero valent iron material, its preparation method, and its application. The prepared biochar material has both adsorption and reduction capabilities. The iron sulfide shell formed on the surface of the nano-zero valent iron can prevent the nano-zero valent iron from contacting oxygen, extend the service life of the nano-zero valent iron, and enhance the reactivity of the nano-zero valent iron.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing modified biochar-supported sulfide nano-zero-valent iron materials includes the following steps:

[0008] S1: Preparation of biochar samples;

[0009] S2: Add the mature biochar sample obtained in S1 to anhydrous ethanol, then add p-tert-butylaniline and azobisisobutyronitrile to the mixed solution, stir thoroughly and react to ensure that the surface of the biochar is fully grafted with tert-butylphenyl groups.

[0010] S3: The biochar with grafted tert-butylphenyl groups obtained in S2 is mixed with an aqueous solution of ferrous sulfate and stirred thoroughly under a protective atmosphere. Then, NaBH4 solution is added dropwise at a uniform rate under the same protective atmosphere. After stirring thoroughly, the mixture is allowed to stand for a period of time. Then, an aqueous solution of sodium dithionite is added dropwise. After stirring thoroughly, the mixture is allowed to stand for a period of time to obtain a suspension.

[0011] S4: The suspension solution was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain modified biochar-supported sulfide nano-zero-valent iron material.

[0012] In the steps described above, the biochar sample in S1 is prepared by using coconut shell as raw material and KOH as activator, and is obtained by high-temperature activation; the biochar sample undergoes secondary activation by a mixed aqueous solution of ZnCl2 and camellia shell, resulting in better adsorption performance;

[0013] In S2, the mass ratio of p-tert-butylaniline to azobisisobutyronitrile is 10:1, the reaction temperature is 70℃, and the reaction time is 12h.

[0014] The ratio of the mass fraction (in g) of the biochar sample in S3 to the molar fraction (in mol) of ferrous sulfate in the ferrous sulfate aqueous solution is 1:(0.015-0.02), and the molar ratio of the added ferrous sulfate to NaBH4 is 5:4.

[0015] The concentration of ferrous sulfate in the ferrous sulfate aqueous solution is 0.08-0.1 mol / L, the concentration of sulfur in the sodium dithionite aqueous solution is 0.02-0.03 mol / L, and the molar ratio of sodium dithionite to ferrous sulfate is (0.008-0.016):1.

[0016] The stirring rate is 120-150 r / min.

[0017] A modified biochar-supported sulfide nano-zero valent iron material, wherein the surface of the biochar material is loaded with particles with nano-zero valent iron as the core and iron sulfide as the shell; the surface of the modified biochar-supported sulfide nano-zero valent iron material contains tert-butylphenyl groups; wherein the molar ratio of sulfur to iron is (0.015-0.03):1, preferably (0.02-0.025):1.

[0018] The biochar material is in powder form with a particle size of 300-700µm.

[0019] The modified biochar-supported sulfide nano-zero-valent iron material described above was applied to the degradation of bromophenols.

[0020] Beneficial effects: This invention provides a modified biochar-supported sulfide nano-zero-valent iron material, its preparation method, and its application, which have the following advantages compared with the prior art:

[0021] (1) The modified biochar-supported sulfidated nano-zero-valent iron material prepared in this invention allows the nano-zero-valent iron to be fully dispersed on the surface of the carrier, effectively avoiding the agglomeration of the nano-zero-valent iron, improving the reactivity and electron transfer rate of the nano-zero-valent iron, and giving full play to its reducing ability. At the same time, the sulfidation treatment of the nano-zero-valent iron can form a ferrous sulfide shell on the surface of the nano-zero-valent iron, protecting the nano-zero-valent iron from oxidation, which can improve its electron utilization and service life, so as to give full play to the high reactivity of the nano-zero-valent iron. In addition, the strong adsorption effect of biochar makes the material relatively excellent in adsorbing and degrading bromophenols.

[0022] (2) The modified biochar-supported sulfide nano-zero-valent iron material prepared by the method of the present invention contains tert-butylphenyl groups on its surface, which can improve the hydrophobicity of the material surface and make it more conducive to the adsorption of bromophenols from wastewater. This makes the material highly efficient in adsorbing and degrading bromophenols. Attached Figure Description

[0023] Figure 1 This is a diagram illustrating the preparation process of modified biochar-supported sulfide nano-zero-valent iron material in this embodiment of the invention.

[0024] Figure 2 The diagram shows the degradation rate of p-bromophenol by the materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0025] The present invention will be described in detail below with reference to specific embodiments: Example 1

[0026] like Figure 1 As shown, a method for preparing modified biochar-supported sulfide nano-zero-valent iron materials includes the following steps:

[0027] 1.8g of coconut shell was added to 100ml of 1mol / L KOH solution and heated at 140℃ for 1h. 0.5g of camellia shell was crushed into powder and mixed with 1.5g of ZnCl2 to form 100ml of aqueous solution. The solution was dried at 120℃ for 3h. The coconut shell activated at high temperature was added to the mixed solution and placed in a tube furnace and heated to 500℃ under N2 atmosphere and held for 1h. The resulting biochar sample was dispersed in 1mol / L hydrochloric acid solution and heated at 80℃ for 1h. The sample was washed with deionized water until the pH reached 7.0. The washed biochar sample was placed in a vacuum oven and dried at 80℃ for 24h to obtain a mature biochar sample.

[0028] Take 1g of the mature biochar sample obtained in the above steps and add it to 100mL of anhydrous ethanol. Then add 0.5g of p-tert-butylaniline and 0.05g of azobisisobutyronitrile to the mixed solution. After stirring thoroughly, maintain the reaction at 70℃ for 12h to ensure that the tert-butylphenyl groups are fully grafted onto the surface of the biochar.

[0029] The biochar sample prepared according to the above steps was mixed with 200 ml of 0.08 mol / L ferrous sulfate aqueous solution and stirred for 1-2 h under N2 atmosphere protection. Then, under N2 atmosphere, 25.6 ml of 0.5 mol / L NaBH4 solution was added dropwise at a uniform rate. After stirring thoroughly, the mixture was allowed to stand for a period of time. Then, 12 ml of 0.01 mol / L sodium dithionite aqueous solution was added dropwise. After stirring thoroughly, the mixture was allowed to stand for a period of time to obtain a suspension.

[0030] The suspension was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain modified biochar-supported sulfide nano-zero-valent iron material. Example 2

[0031] like Figure 1 As shown, a method for preparing modified biochar-supported sulfide nano-zero-valent iron materials includes the following steps:

[0032] 1.8g of coconut shell was added to 100ml of 1mol / L KOH solution and heated at 140℃ for 1h. 0.5g of camellia shell was crushed into powder and mixed with 1.5g of ZnCl2 to form 100ml of aqueous solution. The solution was dried at 120℃ for 3h. The coconut shell activated at high temperature was added to the mixed solution and placed in a tube furnace and heated to 500℃ under N2 atmosphere and held for 1h. The resulting biochar sample was dispersed in 1mol / L hydrochloric acid solution and heated at 80℃ for 1h. The sample was washed with deionized water until the pH reached 7.0. The washed biochar sample was placed in a vacuum oven and dried at 80℃ for 24h to obtain a mature biochar sample.

[0033] Take 1g of the mature biochar sample obtained in the above steps and add it to 100mL of anhydrous ethanol. Then add 0.6g of p-tert-butylaniline and 0.06g of azobisisobutyronitrile to the mixed solution. After stirring thoroughly, maintain the reaction at 70℃ for 12h to ensure that the tert-butylphenyl groups are fully grafted onto the surface of the biochar.

[0034] The biochar sample prepared according to the above steps was mixed with 225 ml of 0.08 mol / L ferrous sulfate aqueous solution and stirred for 1-2 h under N2 atmosphere protection. Then, under the condition of N2, 28.8 ml of 0.5 mol / L NaBH4 solution was added dropwise at a uniform rate. After stirring thoroughly, it was allowed to stand for a period of time. Then, 18 ml of 0.01 mol / L sodium dithionite aqueous solution was added dropwise. After stirring thoroughly, it was allowed to stand for a period of time to obtain a suspension.

[0035] The suspension was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain modified biochar-supported sulfide nano-zero-valent iron material. Example 3

[0036] like Figure 1 As shown, a method for preparing modified biochar-supported sulfide nano-zero-valent iron materials includes the following steps:

[0037] 1.8g of coconut shell was added to 100ml of 1mol / L KOH solution and heated at 140℃ for 1h. 0.5g of camellia shell was crushed into powder and mixed with 1.5g of ZnCl2 to form 100ml of aqueous solution. The solution was dried at 120℃ for 3h. The coconut shell activated at high temperature was added to the mixed solution and placed in a tube furnace and heated to 500℃ under N2 atmosphere and held for 1h. The resulting biochar sample was dispersed in 1mol / L hydrochloric acid solution and heated at 80℃ for 1h. The sample was washed with deionized water until the pH reached 7.0. The washed biochar sample was placed in a vacuum oven and dried at 80℃ for 24h to obtain a mature biochar sample.

[0038] Take 1g of the mature biochar sample obtained in the above steps and add it to 100mL of anhydrous ethanol. Then add 1.0g of p-tert-butylaniline and 0.1g of azobisisobutyronitrile to the mixed solution. After stirring thoroughly, maintain the reaction at 70℃ for 12h to ensure that the tert-butylphenyl groups are fully grafted onto the surface of the biochar.

[0039] The biochar sample prepared according to the above steps was mixed with 200 ml of 0.1 mol / L ferrous sulfate aqueous solution and stirred for 1-2 h under N2 atmosphere protection. Then, under the condition of N2, 32 ml of 0.5 mol / L NaBH4 solution was added dropwise at a uniform rate. After stirring thoroughly, it was allowed to stand for a period of time. Then, 30 ml of 0.01 mol / L sodium dithionite aqueous solution was added dropwise. After stirring thoroughly, it was allowed to stand for a period of time to obtain a suspension.

[0040] The suspension was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain modified biochar-supported sulfide nano-zero-valent iron material.

[0041] Comparative Example 1

[0042] 1.8g of coconut shell was added to 100ml of 1mol / L KOH solution and heated at 140℃ for 1h. 0.5g of camellia shell was crushed into powder and mixed with 1.5g of ZnCl2 to form 100ml of aqueous solution. The solution was dried at 120℃ for 3h. The coconut shell activated at high temperature was added to the mixed solution and placed in a tube furnace and heated to 500℃ under N2 atmosphere and held for 1h. The resulting biochar sample was dispersed in 1mol / L hydrochloric acid solution and heated at 80℃ for 1h. The sample was washed with deionized water until the pH reached 7.0. The washed biochar sample was placed in a vacuum oven and dried at 80℃ for 24h to obtain a mature biochar sample.

[0043] Take 1g of the biochar sample prepared according to the above steps and mix it with 225ml of 0.08mol / L ferrous sulfate aqueous solution. Stir under N2 atmosphere for 1-2h. Then, under N2 atmosphere, add 28.8ml of 0.5mol / L NaBH4 solution dropwise at a uniform rate. After stirring thoroughly, let it stand for a period of time. Then, add 9ml of 0.02mol / L sodium dithionite aqueous solution. After stirring thoroughly, let it stand for a period of time to obtain a suspension.

[0044] The suspension was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain biochar-supported sulfide nano-zero-valent iron material.

[0045] Comparative Example 2

[0046] 1.8g of coconut shell was added to 100ml of 1mol / L KOH solution and heated at 140℃ for 1h. 0.5g of camellia shell was crushed into powder and mixed with 1.5g of ZnCl2 to form 100ml of aqueous solution. The solution was dried at 120℃ for 3h. The coconut shell activated at high temperature was added to the mixed solution and placed in a tube furnace and heated to 500℃ under N2 atmosphere and held for 1h. The resulting biochar sample was dispersed in 1mol / L hydrochloric acid solution and heated at 80℃ for 1h. The sample was washed with deionized water until the pH reached 7.0. The washed biochar sample was placed in a vacuum oven and dried at 80℃ for 24h to obtain a mature biochar sample.

[0047] Take 1g of the mature biochar sample obtained in the above steps and add it to 100mL of anhydrous ethanol. Then add 0.6g of p-tert-butylaniline and 0.06g of azobisisobutyronitrile to the mixed solution. After stirring thoroughly, maintain the reaction at 70℃ for 12h to ensure that the tert-butylphenyl groups are fully grafted onto the surface of the biochar.

[0048] The biochar sample prepared according to the above steps was mixed with 225 ml of 0.08 mol / L ferrous sulfate aqueous solution and stirred for 1-2 h under N2 atmosphere protection. Then, under the condition of N2, 28.8 ml of 0.5 mol / L NaBH4 solution was added dropwise at a uniform rate. After stirring thoroughly, the mixture was allowed to stand for a period of time to obtain a suspension.

[0049] The suspension was subjected to solid-liquid separation, ethanol washing, deionized water washing, sieving, and drying to obtain modified biochar-supported nano-zero-valent iron materials.

[0050] Test: The materials prepared in Examples 1-3 and Comparative Examples 1-2 were placed in 250ml Erlenmeyer flasks, and 100ml of a prepared 200mg / L p-bromophenol solution was added sequentially. The flasks were then placed in a constant temperature shaking incubator and reacted at 60℃ for 3 hours. The remaining concentration of p-bromophenol in the solution after the reaction was determined by high performance liquid chromatography-mass spectrometry. The degradation rate of p-bromophenol in the prepared materials could be calculated based on the difference between the initial concentration and the remaining concentration. The specific degradation rates of p-bromophenol are shown in Table 1. (Table 1 and...) Figure 2 In this document, Example 1 is represented by E1, Example 2 by E2, Example 3 by E3, Comparative Example 1 by F1, and Comparative Example 2 by F2.

[0051] Table 1. Adsorption and degradation rates of p-bromophenol by the materials prepared in Examples 1-3 and Comparative Examples 1-2

[0052]

[0053] From Table 1 and Figure 2 It can be seen that the modified biochar supported on sulfidated nano-zero-valent iron prepared by this invention can achieve efficient degradation of p-bromophenol in a short time. Under the reaction conditions of 60℃ and 3h reaction time, the degradation rate is above 90%, and the optimal embodiment achieves a degradation rate of 94.14% for p-bromophenol. In contrast, the degradation rate of p-bromophenol by carbon materials without hydrophobic groups and carbon materials without sulfidation treatment is less than 70% under the same conditions. This indicates that the modified biochar supported on sulfidated nano-zero-valent iron provided by this invention has excellent p-bromophenol degradation performance, and the technological improvement has achieved significant results.

[0054] The above description is merely a preferred embodiment of the present invention and will help those skilled in the art to further understand the present invention, but it does not limit the present invention in any way. For those skilled in the art, any modifications and improvements made without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing modified biochar-supported sulfide nano-zero-valent iron materials, characterized in that, Includes the following steps: S1: Preparation of biochar; S2: Add the prepared biochar to anhydrous ethanol, then add p-tert-butylaniline and azobisisobutyronitrile to the mixed solution, stir thoroughly and react to ensure that the surface of the biochar is fully grafted with tert-butylphenyl groups. S3: The obtained biochar grafted with tert-butylphenyl groups was mixed with an aqueous solution of ferrous sulfate and stirred thoroughly under a protective atmosphere. Then, NaBH4 solution was added dropwise at a uniform rate under a protective atmosphere. After stirring thoroughly, the mixture was allowed to stand for a period of time. Then, an aqueous solution of sodium dithionite was added dropwise. After stirring thoroughly, the mixture was allowed to stand for a period of time to obtain a suspension. The suspension was then subjected to solid-liquid separation to obtain modified biochar-supported sulfide nano-zero-valent iron material.

2. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1, characterized in that, The biochar described in S1 is prepared by using coconut shells as raw materials and KOH as an activating agent, and is obtained by high-temperature activation.

3. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1 or 2, characterized in that, The biochar described in S1 is subjected to secondary activation through a mixed aqueous solution of ZnCl2 and camellia oleifera shells.

4. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1, characterized in that, The mass ratio of p-tert-butylaniline to azobisisobutyronitrile in S2 is 10:

1.

5. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1 or 4, characterized in that, The reaction temperature of S2 is 79℃ and the reaction time is 12h.

6. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1, characterized in that, The mass ratio of biochar to ferrous sulfate in S3 is 1:(0.015-0.02), the molar ratio of ferrous sulfate to NaBH4 is 5:4, and the molar ratio of sodium dithionite to ferrous sulfate is (0.008-0.016):

1.

7. The method for preparing modified biochar-supported sulfide nano-zero-valent iron material according to claim 1 or 6, characterized in that, The concentration of ferrous sulfate in the ferrous sulfate aqueous solution is 0.08-0.1 mol / L, and the concentration of sulfur in the sodium dithionite aqueous solution is 0.02-0.03 mol / L.

8. A modified biochar-supported sulfide nano-zero-valent iron material, characterized in that, The modified biochar-supported sulfide nano-zero-valent iron material has tert-butylphenyl groups on its surface; the biochar surface is loaded with particles with nano-zero-valent iron as the core and iron sulfide as the shell.

9. The modified biochar-supported sulfide nano-zero-valent iron material according to claim 8, characterized in that, The molar ratio of sulfur to iron in the modified biochar-supported sulfurized nano-zero-valent iron material is (0.015-0.03):

1.

10. The application of the modified biochar-supported sulfide nano-zero-valent iron material according to any one of claims 8-9, characterized in that, The modified biochar-supported sulfidated nano-zero-valent iron material is used for the degradation of bromophenols.

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