Silicon-based adsorbent and application thereof in household garbage incineration waste gas treatment

Abstract

The invention discloses a silicon-based adsorbent and application thereof in household garbage incineration waste gas disposal, the silicon-based adsorbent takes polymer modified composite clay as a matrix, humic acid is loaded on the surface, and the composite clay is a combination of palygorskite, chlorite and illite; the silicon-based adsorbent provided by the invention has excellent adsorption performance on dioxin, can maintain good mechanical properties in both alkaline and neutral environments, can effectively solve the problem that humic acid is extremely easy to dissolve in the neutral and alkaline environments, expands the application range of the adsorbent, and effectively improves the adsorption rate on dioxin.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental governance, and particularly relates to a silicon-based adsorbent and its application in the treatment of waste gas from municipal solid waste incineration. Background Art

[0002] Currently, the methods for treating municipal solid waste in China mainly include landfill, incineration, and composting. Compared with landfill and composting, incineration has the advantages of high reduction, volume reduction, and the heat generated by combustion can be utilized, playing an important role in waste treatment and gradually becoming the main way for municipal solid waste treatment.

[0003] However, dioxins are easily generated during the incineration process. With the continuous improvement of environmental awareness, the emission standards for dioxin-like pollutants in flue gas have become increasingly strict. To meet these standards, waste incineration plants generally adopt the activated carbon adsorption method to control the emission of dioxins. However, the adsorption capacity of activated carbon is limited, and its adsorption ability for dioxins is weak, resulting in poor adsorption effect of activated carbon on dioxins.

[0004] To solve the problem of poor adsorption effect of activated carbon on dioxins, researchers immobilize humic acid on clay or organically and inorganically modified clay for adsorbing dioxins. However, since most clay is charged, after organic or inorganic modification, it becomes positively charged, while humic acid is negatively charged. Through the mutual attraction of positive and negative charges, a humic acid-clay complex is formed, and humic acid adheres to the surface and internal pores of the clay, improving the hydrophobicity of humic acid; at the same time, humic acid also changes the charge on the clay surface; thereby enhancing the adsorption effect of the humic acid-clay complex on dioxins.

[0005] However, humic acid is easily affected by the pH value and is extremely soluble in neutral and alkaline environments, thereby resulting in a decrease in its adsorption effect on dioxins. Although using clay to modify humic acid can reduce the solubility of humic acid in neutral and alkaline environments and improve its adsorption effect on dioxins, the effect is not ideal. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects and deficiencies of the prior art and provide a silicon-based adsorbent. This silicon-based adsorbent has excellent adsorption performance for dioxins, can maintain good mechanical properties in both alkaline and neutral environments, effectively solves the problem that humic acid is extremely soluble in neutral and alkaline environments, expands the application range of the adsorbent, and effectively improves the adsorption rate of dioxins.

[0007] The object of the present invention is to provide a silicon-based adsorbent, which uses a polymer-modified composite clay as the matrix and humic acid is loaded on the surface. The composite clay is a combination of palygorskite, chlorite and illite; the polymer is prepared by polymerizing 4'-vinyl-4-benzobenzoic acid monomers.

[0008] In some embodiments of the present invention, the mass ratio of palygorskite, chlorite and illite is 1-3:1:1-4.

[0009] In some embodiments of the present invention, the mass ratio of 4'-vinyl-4-benzobenzoic acid to the composite clay is 1:2-4.

[0010] Another object of the present invention is to provide a preparation method of the silicon-based adsorbent, comprising the following steps: S1. Under nitrogen protection, mix 4'-vinyl-4-benzobenzoic acid with water, add sodium hydroxide, then add the composite clay, raise the temperature, add an initiator, and continue to raise the temperature for reaction to obtain a polymer-modified composite clay; S2. Add dilute sulfuric acid to the polymer-modified composite clay for activation, then add an aqueous solution of potassium humate, react, and perform post-treatment to obtain the silicon-based adsorbent.

[0011] In some embodiments of the present invention, in S1, the mass ratio of 4'-vinyl-4-benzobenzoic acid to sodium hydroxide and the initiator is 60-80:10-20:1.

[0012] In some embodiments of the present invention, in S1, the initiator is selected from at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.

[0013] In some embodiments of the present invention, in S1, the temperature for raising the temperature is 50-70°C, and the time is 20-40 min.

[0014] In some embodiments of the present invention, in S1, the temperature for continuing the temperature-raising reaction is 80-100°C, and the time is 4-6 hours.

[0015] In some embodiments of the present invention, in S2, the mass ratio of the polymer-modified composite clay to dilute sulfuric acid and the potassium humate solution is 1:8-12:1.5-2.5.

[0016] In some embodiments of the present invention, in S2, the temperature for activation is 20-30°C, and the time is 20-40 min.

[0017] In some embodiments of the present invention, in S2, the temperature for the reaction is 20-30°C, and the time is 50-70 min.

[0018] In some embodiments of the present invention, in S2, the mass concentration of the dilute sulfuric acid is 10% - 20%.

[0019] In some embodiments of the present invention, in S2, the mass concentration of the potassium humate aqueous solution is 4% - 6%.

[0020] Another object of the present invention is to provide the application of the silicon-based adsorbent or the silicon-based adsorbent prepared by the preparation method of the silicon-based adsorbent in the treatment of domestic waste incineration waste gas.

[0021] Compared with the prior art, the present invention has the following beneficial effects: On the one hand, the molecular structure of poly(4'-vinyl-4-benzonic acid) in the present invention contains a conjugated effect, which enhances the hydrogen bond interaction between poly(4'-vinyl-4-benzonic acid) and humic acid. On the other hand, the composite clay of the present invention carries a positive charge, and humic acid carries a negative charge. The positive and negative charges attract each other, enhancing the interaction between the composite clay and humic acid; the combined interaction of the polymer and the composite clay with humic acid enables humic acid to maintain good mechanical properties in both alkaline and neutral environments, effectively solving the problem that humic acid is extremely soluble in neutral and alkaline environments, and improving the adsorption rate of dioxins. Specific Embodiments

[0022] The following will clearly and completely describe the concept and technical effects generated by the present invention in combination with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention. The test methods used in the embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial sources.

[0023] Example 1 This example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, 60 parts by mass of 4'-vinyl-4-benzonic acid is mixed with 360 parts by mass of water, 20 parts by mass of sodium hydroxide is added, and then a mixture of 48 parts by mass of palygorskite, 24 parts by mass of chlorite and 48 parts by mass of illite is added. The temperature is raised to 70°C and kept for 20 minutes. 1 part by mass of ammonium persulfate is added, and the temperature is further raised to 80°C and reacted for 6 hours. The product is washed 3 times with ethanol, dried and pulverized to obtain a polymer-modified composite clay; S2. Add 80 parts by mass of dilute sulfuric acid with a mass concentration of 10% to 10 parts by mass of polymer-modified composite clay, activate at 20 °C for 40 min, then add 15 parts by mass of potassium humate aqueous solution with a mass concentration of 6%, react at 30 °C for 50 min, filter, wash the filter residue 3 times with deionized water, adjust the pH value to 10, dry and crush to obtain a silicon-based adsorbent.

[0024] Example 2 This example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, mix 80 parts by mass of 4'-vinyl-4-biphenylcarboxylic acid with 500 parts by mass of water, add 10 parts by mass of sodium hydroxide, then add a mixture of 120 parts by mass of palygorskite, 40 parts by mass of chlorite and 160 parts by mass of illite, heat up to 50 °C, hold for 40 min, add 1 part by mass of sodium persulfate, continue to heat up to 100 °C and react for 4 hours, wash the product 3 times with ethanol, dry and crush to obtain polymer-modified composite clay; S2. Add 120 parts by mass of dilute sulfuric acid with a mass concentration of 20% to 10 parts by mass of polymer-modified composite clay, activate at 30 °C for 20 min, then add 25 parts by mass of potassium humate aqueous solution with a mass concentration of 4%, react at 20 °C for 70 min, filter, wash the filter residue 3 times with deionized water, adjust the pH value to 10, dry and crush to obtain a silicon-based adsorbent.

[0025] Example 3 This example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, mix 70 parts by mass of 4'-vinyl-4-biphenylcarboxylic acid with 500 parts by mass of water, add 15 parts by mass of sodium hydroxide, then add a mixture of 70 parts by mass of palygorskite, 70 parts by mass of chlorite and 70 parts by mass of illite, heat up to 60 °C, hold for 30 min, add 1 part by mass of potassium persulfate, continue to heat up to 90 °C and react for 5 hours, wash the product 3 times with ethanol, dry and crush to obtain polymer-modified composite clay; S2. Add 100 parts by mass of dilute sulfuric acid with a mass concentration of 15% to 10 parts by mass of polymer-modified composite clay, activate at 25 °C for 30 min, then add 20 parts by mass of potassium humate aqueous solution with a mass concentration of 5%, react at 25 °C for 60 min, filter, wash the filter residue 3 times with deionized water, adjust the pH value to 10, dry and crush to obtain a silicon-based adsorbent.

[0026] Comparative Example 1 This comparative example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, 70 parts by mass of 4'-vinyl-4-biphenylcarboxylic acid is mixed with 500 parts by mass of water, 15 parts by mass of sodium hydroxide is added, then 210 parts by mass of palygorskite is added. The temperature is raised to 60 °C and maintained for 30 min. 1 part by mass of potassium persulfate is added, and the temperature is further raised to 90 °C and reacted for 5 hours. The product is washed with ethanol 3 times, dried and pulverized to obtain polymer-modified composite clay; S2. 10 parts by mass of polymer-modified composite clay is added with 100 parts by mass of dilute sulfuric acid. The mass concentration of the dilute sulfuric acid is 15%. It is activated at 25 °C for 30 min, then 20 parts by mass of potassium humate aqueous solution is added. The mass concentration of the potassium humate aqueous solution is 5%. It reacts at 25 °C for 60 min, filtered. The filter residue is washed with deionized water 3 times, the pH value is adjusted to 10, dried and pulverized to obtain a silicon-based adsorbent.

[0027] Comparative Example 2 This comparative example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, 70 parts by mass of 4'-vinyl-4-biphenylcarboxylic acid is mixed with 500 parts by mass of water, 15 parts by mass of sodium hydroxide is added, then 210 parts by mass of chlorite is added. The temperature is raised to 60 °C and maintained for 30 min. 1 part by mass of potassium persulfate is added, and the temperature is further raised to 90 °C and reacted for 5 hours. The product is washed with ethanol 3 times, dried and pulverized to obtain polymer-modified composite clay; S2. 10 parts by mass of polymer-modified composite clay is added with 100 parts by mass of dilute sulfuric acid. The mass concentration of the dilute sulfuric acid is 15%. It is activated at 25 °C for 30 min, then 20 parts by mass of potassium humate aqueous solution is added. The mass concentration of the potassium humate aqueous solution is 5%. It reacts at 25 °C for 60 min, filtered. The filter residue is washed with deionized water 3 times, the pH value is adjusted to 10, dried and pulverized to obtain a silicon-based adsorbent.

[0028] Comparative Example 3 This comparative example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, 70 parts by mass of 4'-vinyl-4-biphenylcarboxylic acid is mixed with 500 parts by mass of water, 15 parts by mass of sodium hydroxide is added, then 210 parts by mass of illite is added. The temperature is raised to 60 °C and maintained for 30 min. 1 part by mass of potassium persulfate is added, and the temperature is further raised to 90 °C and reacted for 5 hours. The product is washed with ethanol 3 times, dried and pulverized to obtain polymer-modified composite clay; S2. 10 parts by mass of polymer-modified composite clay is added with 100 parts by mass of dilute sulfuric acid. The mass concentration of the dilute sulfuric acid is 15%. It is activated at 25 °C for 30 min, then 20 parts by mass of potassium humate aqueous solution is added. The mass concentration of the potassium humate aqueous solution is 5%. It reacts at 25 °C for 60 min, filtered. The filter residue is washed with deionized water 3 times, the pH value is adjusted to 10, dried and pulverized to obtain a silicon-based adsorbent.

[0029] Comparative Example 4 This comparative example provides a silicon-based adsorbent, and its preparation method includes the following steps: S1. Under nitrogen protection, 15 parts by mass of sodium hydroxide is added to 500 parts by mass of water, and then a mixture of 70 parts by mass of palygorskite, 70 parts by mass of chlorite, and 70 parts by mass of illite is added. The temperature is raised to 60 °C and kept for 30 min. 1 part by mass of potassium persulfate is added, and the temperature is further raised to 90 °C for reaction for 5 hours. The product is washed 3 times with ethanol, dried and pulverized to obtain a polymer-modified composite clay; S2. 100 parts by mass of dilute sulfuric acid with a mass concentration of 15% is added to 10 parts by mass of the polymer-modified composite clay, and it is activated at 25 °C for 30 min. Then 20 parts by mass of an aqueous solution of potassium humate with a mass concentration of 5% is added, and the reaction is carried out at 25 °C for 60 min. It is filtered, and the filter residue is washed 3 times with deionized water. The pH value is adjusted to 10, dried and pulverized to obtain the silicon-based adsorbent.

[0030] Performance tests were carried out on the silicon-based adsorbents of Examples 1 to 3 and Comparative Examples 1 to 4. The test methods are as follows, and the results are shown in Table 1.

[0031] The silicon-based adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were used for the adsorption of dioxins; in a municipal solid waste incineration plant, the waste gas purification treatment was carried out by the method of "SNCR + semi-dry desulfurization + flue gas silicon-based adsorbent injection + bag filter". The silicon-based adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were respectively put in amounts of 0.40 kg / t of waste, 0.50 kg / t of waste, and 0.60 kg / t of waste. According to the method of "Determination of Dioxins in Ambient Air and Exhaust Gas - Isotope Dilution High Resolution Gas Chromatography - High Resolution Mass Spectrometry" (HJ 77.2-2008), dioxins were detected before and after the waste gas purification treatment, and then the removal rate of dioxins was calculated based on the concentrations before and after the treatment.

[0032] Table 1. Performance of the silicon-based adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 4.

[0033]

[0034] As can be seen from Table 1, the silica-based adsorbents prepared in Examples 1 to 3 of the present invention can effectively remove dioxins. On the one hand, the silica-based adsorbents prepared in Examples 1 to 3 of the present invention contain poly(4'-vinyl-4-biphenylcarboxylic acid), and there is a conjugated effect between the molecular structures of the silica-based adsorbents, which enhances the hydrogen bond interaction between poly(4'-vinyl-4-biphenylcarboxylic acid) and humic acid. On the other hand, the composite clay of the present invention has a positive charge, and humic acid has a negative charge. The positive and negative charges attract each other, enhancing the interaction between the composite clay and humic acid. The polymer and the composite clay jointly interact with humic acid, so that humic acid can maintain good mechanical properties in both alkaline and neutral environments, effectively solving the problem that humic acid is extremely soluble in neutral and alkaline environments, and improving the adsorption rate of dioxins. However, the silica-based adsorbents prepared in Comparative Examples 1 to 4 contain a single clay or do not contain poly(4'-vinyl-4-biphenylcarboxylic acid), resulting in an increase in the solubility of humic acid in the silica-based adsorbent in neutral and alkaline environments, and further leading to a decrease in the adsorption rate of the silica-based adsorbent for dioxins.

[0035] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A silicon-based adsorbent, characterized in that: The silicon-based adsorbent uses polymer-modified composite clay as a matrix, and humic acid is loaded on the surface. The composite clay is a combination of palygorskite, chlorite and illite. The polymer is prepared by polymerizing 4'-vinyl-4-biphenylcarboxylic acid monomers.

2. The silicon-based adsorbent according to claim 1, characterized in that The mass ratio of palygorskite, chlorite and illite is 1-3:1:1-4.

3. The silicon-based adsorbent according to claim 1, characterized in that The mass ratio of the 4'-vinyl-4-biphenylcarboxylic acid to the composite clay is 1:2-4.

4. The method for preparing the silicon-based adsorbent according to any one of claims 1 to 3, characterized in that: The steps include: S1. Under nitrogen protection, 4'-vinyl-4-biphenylcarboxylic acid was mixed with water, sodium hydroxide was added, and then the composite clay was added, the temperature was raised, the initiator was added, and the temperature was continued to react to obtain a polymer-modified composite clay; S2. Add dilute sulfuric acid to the polymer-modified composite clay for activation, then add potassium humate aqueous solution, react, and post-treat to obtain a silicon-based adsorbent.

5. The method for preparing a silicon-based adsorbent according to claim 4, characterized in that: In S1, the mass ratio of the 4'-vinyl-4-bibenzoic acid to sodium hydroxide and the initiator is 60-80:10-20:

1.

6. The method for preparing a silicon-based adsorbent according to claim 4, characterized in that: In S1, the initiator is selected from at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

7. The method for preparing a silicon-based adsorbent according to claim 4, characterized in that: In S1, the temperature of the heating is 50-70°C and the time is 20-40 minutes; The temperature of the continued heating reaction is 80-100° C. and the time is 4-6 hours.

8. The method for preparing a silicon-based adsorbent according to claim 4, characterized in that: In S2, the mass ratio of the polymer-modified composite clay to the dilute sulfuric acid and potassium humate solution is 1:8-12:1.5-2.5; The activation temperature is 20-30°C and the activation time is 20-40 minutes; The reaction temperature is 20-30°C and the reaction time is 50-70 minutes.

9. The method for preparing a silicon-based adsorbent according to claim 4, characterized in that: In S2, the mass concentration of the potassium humate aqueous solution is 4% to 6%; The mass concentration of the dilute sulfuric acid is 10% to 20%.

10. Use of the silicon-based adsorbent according to any one of claims 1 to 3 or the silicon-based adsorbent prepared by the preparation method of the silicon-based adsorbent according to any one of claims 4 to 9 in the treatment of waste gas from incineration of domestic waste.

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