Modified biochar loaded vulcanized nano zero-valent iron material as well as preparation method and application thereof

Abstract

The invention discloses a modified biochar-loaded vulcanized nano zero-valent iron material and a preparation method and application thereof, and belongs to the technical field of sewage treatment.The surface of the prepared modified biochar-loaded vulcanized nano zero-valent iron material contains tert-butylphenyl groups, the hydrophobicity of the surface of the biochar material can be enhanced, and the service life of the biochar material is prolonged. The adsorption efficiency on bromophenol substances is improved; meanwhile, the nanoscale zero-valent iron is subjected to vulcanization treatment, a ferrous sulfide shell can be formed on the surface of the nanoscale zero-valent iron, the nanoscale zero-valent iron is protected from being oxidized, and the high reactivity of the nanoscale zero-valent iron is fully exerted; according to the material prepared by the method disclosed by the invention, the nano zero-valent iron is fully dispersed on the surface layer of the carrier, so that the agglomeration phenomenon of the nano zero-valent iron is effectively avoided, the reducing capacity of the nano zero-valent iron is fully exerted, and the degradation of bromophenol substances is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a modified biochar-loaded sulfide nanometer zero-valent iron material, and a preparation method and application thereof. Background Art

[0002] p-Bromophenol is a typical halogenated phenol compound, which is widely used in organic synthesis, analytical chemistry and preservatives. The uses of p-Bromophenol include but are not limited to being used as an intermediate in the synthesis of drugs and dyes, in the preparation of flame retardants or polymer material modifiers, as a colorimetric agent for the detection of metal ions and for the antibacterial treatment of industrial products. Due to its high solubility and bioaccumulation in organic solvents, coupled with its low biodegradability, p-Bromophenol has been widely detected in soil and groundwater. At the same time, p-Bromophenol is biologically toxic, and its potential persistent hazards threaten human health.

[0003] Nano-zero-valent iron materials have become one of the most widely studied nanomaterials in the fields of wastewater treatment, soil and groundwater remediation because of their larger specific surface area and possible nanoscale effects. However, nano-zero-valent iron has problems such as easy agglomeration, easy passivation and easy non-selective reaction, which reduces its reactivity and mobility, limiting its large-scale application in in-situ remediation.

[0004] Among the countermeasures that have been proposed to improve the reactivity of nano zero-valent iron, carrier technology and sulfidation treatment are the most promising and most widely used treatment methods. For example, the patent CN114433020A discloses a method for preparing a composite material of biochar fixed zero-valent iron by co-pyrolysis. The invention adds hematite and biomass to deionized water, stirs them thoroughly, and then ultrasonically treats them. After drying, they are pyrolyzed in a tubular furnace to obtain a composite material of biochar fixed zero-valent iron as an adsorbent for tetracycline; the invention uses a carrier treatment method to effectively solve the problem of easy agglomeration of nano zero-valent iron, but the reduction effect of this method is uncontrollable and limits the full utilization of biomass materials. Patent CN116177710A discloses a method for preparing sulfide biochar loaded with nano zero-valent iron, and applies it to the degradation of tetrabromobisphenol A. A composite material consisting of biochar and particles loaded thereon with zero-valent iron as a core and iron sulfide as a shell is prepared, which improves the electronic efficiency and the degradation efficiency of tetrabromobisphenol A. However, the surface hydrophobicity of the composite material is poor, resulting in its adsorption performance for pollutants not reaching the highest level, which limits its further improvement in the degradation efficiency of pollutants. Summary of the invention

[0005] The present invention provides a modified biochar-loaded sulfide nano zero-valent iron material, a preparation method and application thereof. 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 hinder the contact between the nano zero-valent iron and oxygen, thereby extending the service life of the nano zero-valent iron and enhancing the reactivity of the nano zero-valent iron.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: A method for preparing a modified biochar-loaded sulfided nano zero-valent iron material comprises the following steps: S1: Preparation of biochar samples; S2: Add the mature biochar sample obtained in S1 into anhydrous ethanol, then add p-tert-butylaniline and azobisisobutyronitrile to the mixed solution, stir well and react to ensure that the biochar surface is fully grafted with tert-butylphenyl groups; S3: The biochar grafted with tert-butylphenyl groups obtained in S2 was mixed with an aqueous solution of ferrous sulfate, and stirred thoroughly under a protective atmosphere. Then, NaBH was added dropwise at a uniform rate under the protective atmosphere. 4 The solution is stirred thoroughly and allowed to stand for a period of time, and then an aqueous solution of sodium dithionite is added dropwise, stirred thoroughly and allowed to stand for a period of time to obtain a suspension solution; S4: The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening, and drying to obtain a modified biochar-loaded sulfide nano zero-valent iron material.

[0007] In the above steps, the biochar sample in S1 is prepared by high temperature activation with coconut shell as raw material and KOH as activating agent; the biochar sample is treated with ZnCl 2 The secondary activation of the mixed aqueous solution with camellia oleifera shells has better adsorption performance; The mass ratio of p-tert-butylaniline to azobisisobutyronitrile added in S2 was 10:1, the reaction temperature was 70°C, and the reaction time was 12 h; The ratio of the mass fraction (in g) of the biochar sample described in S3 to the mass fraction (in mol) of the ferrous sulfate substance in the ferrous sulfate aqueous solution is 1:(0.015-0.02). The added ferrous sulfate and NaBH 4 The ratio of the amount of substance is 5:4; 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 the added amounts of sodium dithionite and ferrous sulfate is (0.008-0.016): 1; The stirring rate is 120-150r / min.

[0008] A modified biochar-loaded 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-loaded 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.

[0009] The biochar material is in powder form with a particle size of 300-700 μm.

[0010] The above-mentioned modified biochar-loaded sulfide nano zero-valent iron material is applied to the degradation of bromophenols.

[0011] Beneficial effects: The present invention provides a modified biochar-loaded sulfided nano-zero-valent iron material and a preparation method and application thereof, which has the following advantages over the prior art: (1) The modified biochar-loaded sulfide nano-zero-valent iron material prepared by the present 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, thereby improving its electron utilization rate and service life, and giving full play to the high reactivity of the nano-zero-valent iron; coupled with the strong adsorption effect of biochar, this makes the material relatively effective in adsorbing and degrading bromophenols; (2) The surface of the modified biochar-loaded sulfide nano-zero-valent iron material prepared by the method of the present invention contains tert-butylphenyl groups, which can improve the hydrophobicity of the material surface and is more conducive to its adsorption of bromophenols from wastewater, thereby making the material highly efficient in the adsorption and degradation of bromophenols. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram showing the preparation process of the modified biochar-loaded sulfide nano zero-valent iron material in an embodiment of the present invention; Figure 2 Schematic diagram of the degradation rate of p-bromophenol by the materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with specific embodiments: Example 1

[0014] like Figure 1 As shown, a method for preparing a modified biochar-loaded sulfide nano zero-valent iron material comprises the following steps: 1.8 g coconut shell was added to 100 ml of 1 mol / L KOH solution and heated at 140 °C for 1 h. 0.5 g camellia oleifera shell was crushed into powder and mixed with 1.5 g ZnCl 2 Mix into 100 ml aqueous solution, dry at 120 °C for 3 h, add high temperature activated coconut shell into the mixed solution, place in a tube furnace under N 2 The samples were heated to 500°C and maintained for 1 h under atmosphere protection, and the obtained biochar samples were dispersed in 1 mol / L hydrochloric acid solution, heated at 80°C for 1 h, washed with deionized water until the pH reached 7.0, and the washed biochar samples were placed in a vacuum oven and dried at 80°C for 24 h to obtain mature biochar samples; Take 1 g of the mature biochar sample obtained in the above step and add it to 100 mL of anhydrous ethanol. Then add 0.5 g of p-tert-butylaniline and 0.05 g of azobisisobutyronitrile to the mixed solution. After sufficient stirring, keep the reaction at 70 ° C for 12 h to ensure that the tert-butylphenyl group is fully grafted on the surface of the biochar. The biochar sample prepared according to the above steps was mixed with 200 ml of 0.08 mol / L ferrous sulfate aqueous solution and heated under N 2 Stir for 1-2 h under atmosphere protection, then continue to flow N 2 Under the conditions, 25.6 ml of 0.5 mol / L NaBH was added dropwise at a uniform rate. 4 The solution was stirred thoroughly and allowed to stand for a period of time, and then 12 ml of a 0.01 mol / L sodium dithionite aqueous solution was added dropwise, stirred thoroughly and allowed to stand for a period of time to obtain a suspension solution; The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening and drying to obtain modified biochar-loaded sulfide nano zero-valent iron material. Example 2

[0015] like Figure 1 As shown, a method for preparing a modified biochar-loaded sulfide nano zero-valent iron material comprises the following steps: 1.8 g coconut shell was added to 100 ml of 1 mol / L KOH solution and heated at 140 °C for 1 h. 0.5 g camellia oleifera shell was crushed into powder and mixed with 1.5 g ZnCl 2 Mix into 100 ml aqueous solution, dry at 120 °C for 3 h, add high temperature activated coconut shell into the mixed solution, place in a tube furnace under N 2The samples were heated to 500°C and maintained for 1 h under atmosphere protection, and the obtained biochar samples were dispersed in 1 mol / L hydrochloric acid solution, heated at 80°C for 1 h, washed with deionized water until the pH reached 7.0, and the washed biochar samples were placed in a vacuum oven and dried at 80°C for 24 h to obtain mature biochar samples; 1 g of the mature biochar sample obtained in the above step was added to 100 mL of anhydrous ethanol, and then 0.6 g of p-tert-butylaniline and 0.06 g of azobisisobutyronitrile were added to the mixed solution. After sufficient stirring, the reaction was maintained at 70 ° C for 12 h to ensure that the tert-butylphenyl groups were fully grafted on the surface of the biochar. The biochar sample prepared according to the above steps was mixed with 225 ml of 0.08 mol / L ferrous sulfate aqueous solution and heated to 40 °C in N 2 Stir for 1-2 h under atmosphere protection, then continue to flow N 2 Under the conditions, 28.8 ml of 0.5 mol / L NaBH was added dropwise at a uniform rate. 4 The solution was stirred thoroughly and allowed to stand for a period of time, and then 18 ml of a 0.01 mol / L sodium dithionite aqueous solution was added dropwise, stirred thoroughly and allowed to stand for a period of time to obtain a suspension solution; The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening and drying to obtain modified biochar-loaded sulfide nano zero-valent iron material. Example 3

[0016] like Figure 1 As shown, a method for preparing a modified biochar-loaded sulfide nano zero-valent iron material comprises the following steps: 1.8 g coconut shell was added to 100 ml of 1 mol / L KOH solution and heated at 140 °C for 1 h. 0.5 g camellia oleifera shell was crushed into powder and mixed with 1.5 g ZnCl 2 Mix into 100 ml aqueous solution, dry at 120 °C for 3 h, add high temperature activated coconut shell into the mixed solution, place in a tube furnace under N 2 The samples were heated to 500°C and maintained for 1 h under atmosphere protection, and the obtained biochar samples were dispersed in 1 mol / L hydrochloric acid solution, heated at 80°C for 1 h, washed with deionized water until the pH reached 7.0, and the washed biochar samples were placed in a vacuum oven and dried at 80°C for 24 h to obtain mature biochar samples; Take 1 g of the mature biochar sample obtained in the above step and add it to 100 mL of anhydrous ethanol. Then add 1.0 g of p-tert-butylaniline and 0.1 g of azobisisobutyronitrile to the mixed solution. After sufficient stirring, keep the reaction at 70 ° C for 12 h to ensure that the tert-butylphenyl group is fully grafted on the surface of the biochar. The biochar sample prepared according to the above steps was mixed with 200 ml of 0.1 mol / L ferrous sulfate aqueous solution and heated under N 2 Stir for 1-2 h under atmosphere protection, then continue to flow N 2 Under the conditions, 32 ml of 0.5 mol / L NaBH was added dropwise at a uniform rate. 4 The solution was stirred thoroughly and allowed to stand for a period of time, and then 30 ml of a 0.01 mol / L sodium dithionite aqueous solution was added dropwise, stirred thoroughly and allowed to stand for a period of time to obtain a suspension solution; The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening and drying to obtain modified biochar-loaded sulfide nano zero-valent iron material.

[0017] Comparative Example 1 1.8 g coconut shell was added to 100 ml of 1 mol / L KOH solution and heated at 140 °C for 1 h. 0.5 g camellia oleifera shell was crushed into powder and mixed with 1.5 g ZnCl 2 Mix into 100 ml aqueous solution, dry at 120 °C for 3 h, add high temperature activated coconut shell into the mixed solution, place in a tube furnace under N 2 The samples were heated to 500°C and maintained for 1 h under atmosphere protection, and the obtained biochar samples were dispersed in 1 mol / L hydrochloric acid solution, heated at 80°C for 1 h, washed with deionized water until the pH reached 7.0, and the washed biochar samples were placed in a vacuum oven and dried at 80°C for 24 h to obtain mature biochar samples; 1 g of the biochar sample prepared in the above steps was mixed with 225 ml of 0.08 mol / L ferrous sulfate aqueous solution and heated under N 2 Stir for 1-2 h under atmosphere protection, then continue to flow N 2 Under the conditions, 28.8 ml of 0.5 mol / L NaBH was added dropwise at a uniform rate. 4 The solution was stirred thoroughly and allowed to stand for a period of time, and then 9 ml of a 0.02 mol / L aqueous solution of sodium dithionite was added dropwise, stirred thoroughly and allowed to stand for a period of time to obtain a suspended solution; The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening and drying to obtain the biochar-loaded sulfide nano zero-valent iron material.

[0018] Comparative Example 2 1.8 g coconut shell was added to 100 ml of 1 mol / L KOH solution and heated at 140 °C for 1 h. 0.5 g camellia oleifera shell was crushed into powder and mixed with 1.5 g ZnCl 2Mix into 100 ml aqueous solution, dry at 120 °C for 3 h, add high temperature activated coconut shell into the mixed solution, place in a tube furnace under N 2 The samples were heated to 500°C and maintained for 1 h under atmosphere protection, and the obtained biochar samples were dispersed in 1 mol / L hydrochloric acid solution, heated at 80°C for 1 h, washed with deionized water until the pH reached 7.0, and the washed biochar samples were placed in a vacuum oven and dried at 80°C for 24 h to obtain mature biochar samples; 1 g of the mature biochar sample obtained in the above step was added to 100 mL of anhydrous ethanol, and then 0.6 g of p-tert-butylaniline and 0.06 g of azobisisobutyronitrile were added to the mixed solution. After sufficient stirring, the reaction was maintained at 70 ° C for 12 h to ensure that the tert-butylphenyl groups were fully grafted on the surface of the biochar. The biochar sample prepared according to the above steps was mixed with 225 ml of 0.08 mol / L ferrous sulfate aqueous solution and heated to 40 °C in N 2 Stir for 1-2 h under atmosphere protection, then continue to flow N 2 Under the conditions, 28.8 ml of 0.5 mol / L NaBH was added dropwise at a uniform rate. 4 The solution is stirred thoroughly and then allowed to stand for a period of time to obtain a suspension solution; The suspended solution is subjected to solid-liquid separation, ethanol washing, deionized water washing, screening and drying to obtain modified biochar-loaded nano zero-valent iron material.

[0019] Test: The materials prepared in Examples 1-3 and Comparative Examples 1-2 were placed in 250 ml conical flasks, and 100 ml of the prepared 200 mg / L p-bromophenol solution was added in sequence. The conical flasks were then placed in a constant temperature shaking incubator and reacted at 60° C. for 3 h. The residual 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 by the prepared materials was calculated based on the difference between the initial concentration and the residual concentration. The specific degradation rate of p-bromophenol is shown in Table 1. In Tables 1 and Figure 2 , Example 1 is represented by E1, Example 2 is represented by E2, Example 3 is represented by E3, Comparative Example 1 is represented by F1, and Comparative Example 2 is represented by F2.

[0020] Table 1 Adsorption degradation rate of p-bromophenol by the materials prepared in Examples 1-3 and Comparative Examples 1-2

[0021] From Table 1 and Figure 2It can be seen that the modified biochar-loaded sulfide nano zero-valent iron material prepared by the present invention can achieve efficient degradation of p-bromophenol in a relatively short time, and the degradation rate is above 90% under the reaction conditions of 60°C and 3h reaction time, and the degradation rate of p-bromophenol in the optimal embodiment reaches 94.14%. In contrast, the degradation rates of p-bromophenol by carbon materials without hydrophobic groups and carbon materials without sulfide treatment under the same conditions are less than 70%, indicating that the modified biochar-loaded sulfide nano zero-valent iron material provided by the present invention has excellent p-bromophenol degradation performance, and the technical improvement has significant results.

[0022] The above is only a preferred embodiment of the present invention, which will help those skilled in the art to further understand the present invention, but does not limit the present invention in any form. For those skilled in the art, without departing from the concept of the present invention, several modifications and improvements made are within the scope of protection of the present invention.

Claims

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

2. The method for preparing the modified biochar-loaded sulfide nano zero-valent iron material according to claim 1, characterized in that: The biochar described in S1 is prepared by using coconut shell as raw material and KOH as activating agent through high temperature activation.

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

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

1.

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

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

1.

7. The method for preparing the modified biochar-loaded 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-loaded sulfided nano zero-valent iron material, characterized in that: The surface of the modified biochar-loaded sulfide nano zero-valent iron material contains tert-butylphenyl groups; the surface of the biochar is loaded with particles with nano zero-valent iron as the core and iron sulfide as the shell.

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

1.

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

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