CN114768807A - Iron-carbon composite Fenton catalyst and preparation method and application thereof - Google Patents

Abstract

The invention discloses an iron-carbon composite Fenton catalyst and a preparation method and application thereof, based on the fact that kitchen waste contains a large amount of biomass and is rich in organic carbon substances, the kitchen waste is reacted with an iron salt solution to prepare the composite Fenton catalyst through a one-step method, the kitchen waste is recycled through simple and easy operation, the preparation method is easy to realize, the prepared composite catalyst is high in catalytic efficiency, strong in self-regeneration capacity and low in cost, and therefore the defects of low efficiency, difficulty in regeneration, large using amount and high cost of the traditional Fenton catalyst are overcome, and meanwhile, the kitchen waste is recycled.

Description

A kind of iron-carbon composite Fenton catalyst and its preparation method and application

technical field

The invention belongs to the fields of water treatment and solid waste treatment and resource utilization, and relates to an iron-carbon composite Fenton catalyst and a preparation method and application thereof.

Background technique

The Fenton reaction is that under acidic conditions, hydrogen peroxide (H ₂ O ₂ ) generates hydroxyl radicals (OH) under the action of catalyst ferrous (Fe ²⁺ ), and the OH redox potential is as high as 2.80V, which is extremely oxidizing. , with electronegativity or electrophilicity, the electron affinity can reach 569.3kJ, and it has strong addition reaction characteristics. OH can react with most organic substances without selectivity. It is difficult to handle in biological degradation and chemical oxidation. It shows unique advantages in the treatment of high-concentration and toxic refractory pollutants.

The core of the Fenton method is the Fenton reagent system. The traditional Fenton reagent uses ferrous (Fe ²⁺ ) solution as a catalyst to degrade pollutants through homogeneous Fenton action. With the deepening of research, a variety of modified Fenton reagents have been developed. Or Fenton-like reagents, including solid-phase and liquid-phase catalysts, work through heterogeneous or homogeneous Fenton, and introduce photochemistry and electrochemistry into the Fenton reaction system to form a variety of Fenton or Fenton-like systems to enhance Fenton effect and improve pollution It can overcome the insufficient utilization rate of H ₂ O ₂ , the insufficient mineralization of organic matter, the pH value of the effective reaction solution is limited to about 3.0, and a large amount of iron sludge that needs to be further processed is produced after the reaction, the regeneration of Fenton reagent is slow, and the use cost is high Inadequate Fenton response.

Food waste is the waste generated in the process of family diet, catering industry, food processing, etc. Food waste contains a large amount of biomass such as cellulose, hemicellulose, lignin, starch, protein and lipids. High-quality raw materials for the preparation of carbon-containing substances such as biochar. It is very necessary and urgent to carry out the harmless treatment and resource recycling of the perishable kitchen waste.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems in the prior art, and to provide an iron-carbon composite Fenton catalyst and a preparation method and application thereof.

To achieve the above object, the present invention adopts the following technical solutions to realize:

A method for preparing an iron-carbon composite Fenton catalyst, comprising:

Step 1, carry out sorting, impurity removal and crushing and homogenizing pretreatment on the kitchen waste;

Step 2, adding deionized water to the pretreated kitchen waste, heating and stirring, then adding an iron salt solution, and continuing to heat and stir to obtain a liquid-solid mixed product;

Step 3, the liquid-solid mixed product is cooled to room temperature, and the liquid-solid separation is performed to obtain a solid product;

In step 4, the separated solid product is washed and then dried to obtain an iron-carbon composite Fenton catalyst.

Further, in step 1, the kitchen waste is first sorted to remove impurities, and the removed impurities are one or more of glass, metal, plastic, and ceramics.

Further, in step 1, the kitchen waste after sorting and impurity removal is crushed and homogenized by a stirring crusher, and then drained, and the waste liquid is used to recover grease.

Further, in step 2, the ratio w/v of the amount of kitchen waste added to deionized water is 1:1, and the molar mass of iron in the iron salt solution added to the kitchen waste and deionized water is 0.1-0.5 mol/L , the ferric salt solution is selected from at least one of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride and ferric nitrate.

Further, in step 2, after adding the iron salt solution, 5-10 mL of anhydrous ethanol is added dropwise as a dispersant, and stirred for 5-10 min.

Further, in step 2, the first heating temperature is 40～50 ℃, the stirring time is 10～30min, the second heating temperature is raised to 150～350 ℃, the heating rate is 2～5 ℃/min, and the stirring speed is 100～200r/min, stirring time is 1～10h.

Further, in step 3, the liquid-solid mixed product is separated by vacuum filtration to obtain a solid product.

Further, in step 4, the solid product is washed 2-3 times with deionized water and anhydrous ethanol, and dried with a vacuum drying oven, the temperature of the vacuum drying oven is 60-70 °C, and the drying time is 12-24 h .

An iron-carbon composite Fenton catalyst prepared by the preparation method.

The application of the iron-carbon composite Fenton catalyst in degrading trinitrotoluene TNT in wastewater.

Compared with the prior art, the present invention has the following beneficial effects:

The invention provides a method for preparing an iron-carbon composite Fenton catalyst, which is based on the fact that kitchen waste contains a large amount of biomass and is rich in organic carbon materials, and uses the kitchen waste as a raw material to react an iron salt solution with the kitchen waste through a one-step method. The preparation of iron-carbon composite Fenton catalyst has the advantages of simple preparation process, convenient operation, environmental protection and high efficiency, and easy implementation; through simple and easy operation, the kitchen waste is recycled and reused, and the produced iron-carbon composite Fenton catalyst can be combined with hydrogen peroxide. (H ₂ O ₂ ) combined, with the help of iron-carbon micro-electrolysis effect, using carbon as the electron transfer channel of solid-phase Fenton catalyst to improve the generation of OH and the cycle efficiency of Fe ²⁺ , and promote the conversion of Fe ³⁺ to Fe ²⁺ , An efficient Fenton reaction system is formed to promote the degradation of pollutants in wastewater. It has strong self-regeneration ability and low cost, and can solve the problems of low efficiency, difficult regeneration, large dosage and high cost of traditional Fenton catalysts, and has important practical application value. At the same time, it reduces the pollution and harm caused by kitchen waste, and the recycling of kitchen waste can also bring new energy substances to waste water treatment, so as to achieve the purpose of treating waste with waste, save energy and increase efficiency, and improve food efficiency. The transformation of kitchen waste into carbon materials is equivalent to sequestering carbon, which has very broad application prospects.

Description of drawings

In order to describe the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a graph showing the change of degradation rate with reaction time when the iron-carbon composite Fenton catalyst prepared in Example 1 of the present invention degrades TNT.

Fig. 2 is a graph showing the change of degradation rate with reaction time when the iron-carbon composite Fenton catalyst prepared in Example 2 of the present invention degrades TNT.

Fig. 3 is a graph showing the change of degradation rate with reaction time when the iron-carbon composite Fenton catalyst prepared in Example 3 of the present invention degrades TNT.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The invention provides a method for preparing an iron-carbon composite Fenton catalyst, comprising the following steps:

Step 1, pretreatment such as sorting, removing impurities and homogenizing the kitchen waste;

Step 2: Add deionized water to the pretreated kitchen waste at a w/v ratio of 1:1, heat the mixture to 40-50°C, stir for 10-30min, and then use the molar mass of iron Add iron salt solution to 0.1～0.5mol/L, add 5～10mL absolute ethanol dropwise as dispersant, stir for 5～10min, continue heating to raise the temperature to 150～350℃, the heating rate is 2～5℃/min , and stir at a speed of 100 to 200 r/min for 1 to 10 h to obtain a liquid-solid mixed product;

Step 3, the liquid-solid mixed product is cooled to room temperature, and the solid product is obtained by vacuum filtration and separation;

In step 4, the separated solid product is washed 2-3 times with deionized water and absolute ethanol, and then dried in a vacuum drying oven at 60-70° C. for 12-24 hours to obtain an iron-carbon composite Fenton catalyst.

In step 2, the iron salt solution is selected from at least one of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride and ferric nitrate.

Example 1

Collect a certain amount of kitchen waste, sort and remove impurities, remove impurities that cannot be carbonized, such as glass, metal, ceramics, etc., use a stirring and crusher to crush and homogenize, then drain the kitchen waste, weigh and drain After 100g of kitchen waste, add 100ml of deionized water to mix, add the mixture to a 500ml stainless steel reactor, heat the mixture to 40°C, stir for 10min, and add ferric nitrate (Fe(NO ₃ ) ₃ ) solution to the In the mixed solution (0.1mol/L), 5ml of absolute ethanol was added dropwise as a dispersant, and stirring was continued for 5min; after the reactor was sealed, it was placed in a hydrothermal reaction device equipped with temperature control, electric heating and stirring for gradient heating. , the heating program is 170°C (1h), 200°C (3h), 230°C (5h) and 260°C (10h), while stirring (100r/min), the heating rate is maintained at 3°C/min; after the reaction, the reaction The kettle was cooled down, and after being naturally cooled to room temperature, the liquid-solid mixed product was taken out, placed on a vacuum filtration device to separate the solid, collected the solid product, washed twice with deionized water and anhydrous ethanol, and then placed in a vacuum drying oven Under drying conditions at 60 °C, drying was carried out for 12 h to obtain an iron-carbon composite Fenton catalyst.

Example 2

Collect a certain amount of kitchen waste, sort and remove impurities, remove impurities that cannot be carbonized, such as glass, metal, ceramics, etc., use a stirring and crusher to crush and homogenize, then drain the kitchen waste, weigh and drain After 150g of kitchen waste, add 150ml of deionized water to mix, add the mixture to a 500ml stainless steel reactor, heat the mixture to 45°C, stir for 20min, and add ferric chloride (FeCl ₃ ) solution to the mixture (0.3mol/L), add 7.5ml of absolute ethanol dropwise as a dispersant, continue to stir for 8min; after the reactor is sealed, place it in a hydrothermal reaction device equipped with temperature control, electric heating and stirring to carry out gradient heating, and the temperature rises Program 180°C (1h), 210°C (3h), 240°C (5h) and 270°C (10h), while stirring (150r/min), the heating rate is kept at 4°C/min; after the reaction, the reactor is cooled down , after cooling to room temperature naturally, take out the liquid-solid mixed product, place it on a vacuum filtration device to separate the solid, collect the solid product, wash twice with deionized water and anhydrous ethanol, and then place it in a vacuum drying oven at 70°C Under drying conditions, dry for 18h to obtain an iron-carbon composite Fenton catalyst.

Example 3

Collect a certain amount of kitchen waste, sort and remove impurities, remove impurities that cannot be carbonized, such as glass, metal, ceramics, etc., use a stirring and crusher to crush and homogenize, then drain the kitchen waste, weigh and drain After 200g of kitchen waste, add 200ml of deionized water to mix, add the mixture to a 500ml stainless steel reactor, heat the mixture to 50°C, stir for 30min, and add iron sulfide (FeSO ₄ ) solution to the mixture (0.5mol/L), add 10ml absolute ethanol dropwise as a dispersant, and continue to stir for 10min; after the reactor is sealed, it is placed in a hydrothermal reaction device equipped with temperature control, electric heating and stirring to carry out gradient heating, and the heating program is 190 ℃(1h), 220℃(3h), 250℃(5h) and 280℃(10h), while stirring (200r/min), the heating rate was kept at 5℃/min; After naturally cooling to room temperature, the liquid-solid mixed product was taken out, placed on a vacuum filtration device to separate the solid, collected the solid product, washed three times each with deionized water and anhydrous ethanol, and then placed in a vacuum drying box to dry at 70°C and drying for 24 h to obtain an iron-carbon composite Fenton catalyst.

Example 4

Collect a certain amount of kitchen waste, sort and remove impurities, remove impurities that cannot be carbonized, such as glass, metal, ceramics, etc., use a stirring and crusher to crush and homogenize, then drain the kitchen waste, weigh and drain After 120g of kitchen waste, add 120ml of deionized water to mix, add the mixture to a 500ml stainless steel reaction kettle, heat the mixture to 45°C, stir for 10min, and mix iron sulfide (FeSO ₄ ), iron chloride (FeCl ₃ ) The solution is added to the mixed solution (0.2mol/L), 10ml of absolute ethanol is added dropwise as a dispersant, and stirring is continued for 8min; after the reactor is sealed, it is placed in a hydrothermal reaction device equipped with temperature control, electric heating and stirring Gradient heating was carried out during the heating process, and the heating program was 150°C (1h), 200°C (3h), 250°C (5h) and 300°C (7h), while stirring (180r/min), the heating rate was maintained at 5°C/min; the reaction After the end, the reaction kettle was cooled down, and after being naturally cooled to room temperature, the liquid-solid mixed product was taken out, placed on a vacuum filtration device to separate the solid, collected the solid product, washed three times with deionized water and anhydrous ethanol, and then placed Under the drying condition of 65 ℃ in a vacuum drying oven, dry for 15 h to obtain an iron-carbon composite Fenton catalyst.

Example 5

Collect a certain amount of kitchen waste, sort and remove impurities, remove impurities that cannot be carbonized, such as glass, metal, ceramics, etc., use a stirring and crusher to crush and homogenize, then drain the kitchen waste, weigh and drain After 180g of kitchen waste, add 180ml of deionized water to mix, add the mixture into a 500ml stainless steel reaction kettle, heat the mixture to 50°C, stir for 20min, and mix iron sulfide (FeSO ₄ ), iron nitrate (Fe (Fe) NO ₃ ) ₃ ) solution was added to the mixed solution (0.4mol/L), 10 ml of absolute ethanol was added dropwise as a dispersant, and stirring was continued for 7 minutes; after the reactor was sealed, it was placed in water equipped with temperature control, electric heating and stirring Gradient heating was carried out in the thermal reaction device, and the heating program was 150°C (1h), 200°C (2h), 280°C (4h) and 350°C (6h), while stirring (160r/min), the heating rate was maintained at 5°C/ min; after the reaction is completed, the reaction kettle is cooled down, and after being naturally cooled to room temperature, the liquid-solid mixed product is taken out, placed on a vacuum filtration device to separate the solid, and the solid product is collected and washed twice with deionized water and absolute ethanol each. , and then placed in a vacuum drying oven at 60 °C for drying for 20 h to obtain an iron-carbon composite Fenton catalyst. Application of iron-carbon composite Fenton catalyst in the degradation of trinitrotoluene (TNT) in wastewater:

The iron-carbon composite Fenton catalyst prepared in Example 1 was applied to degrade TNT in wastewater, and the specific steps were as follows: the initial concentration of TNT was 50 mg/L, the catalyst dosage was 0.3 g/L, and the H ₂ O ₂ concentration was 0.8 mol/L , when pH=5.0, the Fenton reaction was catalyzed to degrade TNT. The results are shown in Figure 1. The degradation rate of TNT varies with the reaction time, and the final degradation rate can reach 68.64%;

The iron-carbon composite Fenton catalyst prepared in Example 2 was applied to degrade TNT in wastewater, and the specific steps were as follows: the initial concentration of TNT was 50 mg/L, the catalyst dosage was 0.3 g/L, and the H ₂ O ₂ concentration was 0.8 mol/L , under the condition of pH=5.0, when catalyzing the Fenton reaction to degrade TNT, the results are shown in Figure 2. The TNT degradation rate changes with the reaction time, and the TNT degradation rate can reach 95.72;

The iron-carbon composite Fenton catalyst prepared in Example 3 was applied to degrade TNT in wastewater, and the specific steps were as follows: the initial concentration of TNT was 50 mg/L, the catalyst dosage was 0.3 g/L, and the H ₂ O ₂ concentration was 0.8 mol/L , under the condition of pH=5.0, when catalyzing the Fenton reaction to degrade TNT, the results are shown in Figure 3. The degradation rate of TNT varies with time, and the degradation rate of TNT can reach 92.16.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for preparing an iron-carbon composite Fenton catalyst is characterized by comprising the following steps:

step 1, carrying out sorting, impurity removal and crushing and homogenizing pretreatment on kitchen waste;

step 2, adding deionized water into the pretreated kitchen waste, heating and stirring, adding an iron salt solution, and continuing heating and stirring to obtain a liquid-solid mixed product;

step 3, cooling the liquid-solid mixed product to room temperature, and carrying out liquid-solid separation to obtain a solid product;

and 4, cleaning and drying the separated solid product to obtain the iron-carbon composite Fenton catalyst.

2. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 1, the kitchen waste is firstly sorted to remove impurities, and the removed impurities are one or more of glass, metal, plastic and ceramic.

3. The method for preparing the iron-carbon composite Fenton catalyst according to claim 2, wherein in the step 1, the kitchen waste after sorting and impurity removal is subjected to crushing and homogenizing treatment by using a stirring crusher, then is drained, and grease is recovered from waste liquid.

4. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 2, the w/v ratio of the added kitchen waste to the added deionized water is 1: 1, the molar mass of iron in an iron salt solution added into the kitchen waste and deionized water is 0.1-0.5 mol/L, and the iron salt solution is at least one of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride and ferric nitrate.

5. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 2, 5-10 mL of absolute ethyl alcohol is added dropwise as a dispersing agent after the ferric salt solution is added, and the mixture is stirred for 5-10 min.

6. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 2, the first heating temperature is 40-50 ℃, the stirring time is 10-30 min, the second heating temperature is increased to 150-350 ℃, the temperature increase rate is 2-5 ℃/min, the stirring speed is 100-200 r/min, and the stirring time is 1-10 h.

7. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 3, the liquid-solid mixed product is subjected to vacuum filtration separation to obtain a solid product.

8. The method for preparing the iron-carbon composite Fenton catalyst according to claim 1, wherein in the step 4, the solid product is washed 2-3 times by using deionized water and absolute ethyl alcohol respectively, and dried by using a vacuum drying oven, wherein the temperature of the vacuum drying oven is 60-70 ℃, and the drying time is 12-24 hours.

9. An iron-carbon composite Fenton catalyst prepared by the preparation method of any one of claims 1 to 8.

10. The use of the iron-carbon composite Fenton catalyst of claim 9 in the degradation of trinitrotoluene TNT in wastewater.

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