Efficient adsorbent for dioxin and heavy metal in household garbage incineration waste gas and preparation method of efficient adsorbent

Abstract

The invention discloses an efficient adsorbent for dioxin and heavy metal in household garbage incineration waste gas and a preparation method of the efficient adsorbent, and belongs to the technical field of waste gas treatment. The preparation method of the adsorbent comprises the following steps: S1, sequentially modifying a mesoporous silica-based molecular sieve with tetraethylenepentamine and organic acid to prepare a material A; s2, firstly acidizing clay mineral powder, and then performing amination by using a silane coupling agent to obtain a material B; s3, modifying anhydrous gypsum by using octadecyl hydroxyl sulphobetaine to obtain a material C; and S4, the material A, the material B and the material C are mixed and subjected to wet ball milling, an adsorbent is obtained and used for treating waste gas generated by household garbage incineration, and through the synergistic effect of all the components, stable and effective adsorption of dioxin and heavy metal in the household garbage incineration waste gas is effectively achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and particularly relates to a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration waste gas and a preparation method thereof. Background Art

[0002] During the waste incineration process, some secondary pollutants will be generated, such as particulate matter, acidic gases (such as HCl, SO2), dioxins, heavy metals, and volatile organic compounds (VOCs), etc. Among them, dioxins are a class of organic compounds with extremely strong toxicity, and their toxicity is more than 1000 times that of potassium cyanide, which is carcinogenic, mutagenic, and teratogenic to the human body; heavy metals such as mercury, lead, cadmium, etc. will also cause serious harm to human health and the environment. Therefore, how to effectively remove dioxins and heavy metals in waste incineration waste gas has become an important topic in the current environmental protection field.

[0003] Currently, adsorbents are generally used to treat the waste gas generated by domestic waste incineration to reduce the impact of pollutants in the waste gas on the environment. The adsorbents mainly include activated carbon-based adsorbents, molecular sieve-based adsorbents, metal oxide-based adsorbents, etc. Although these adsorbents can effectively adsorb pollutants in the waste gas, their adsorption capacity is limited, and they are easily interfered by substances such as moisture and organic matter. Especially, domestic waste contains various organic matters, inorganic matters, plastics, metals, etc., and various pollutants will be generated during the incineration process. The traditional adsorbents have a weaker effect on waste gas containing multiple pollutants than on waste gas containing a single pollutant, and the adsorption cost is relatively high, which limits the application of the adsorbents.

[0004] Based on this, if an adsorbent that can stably adsorb dioxins and heavy metals can be designed, it will be beneficial to the development of waste incineration waste gas treatment technology. Summary of the Invention

[0005] Aiming at the defects of the prior art, the present invention effectively realizes the stable adsorption of dioxins and heavy metals in domestic waste incineration waste gas through the synergistic effect of modified molecular sieve, aminated clay mineral, and modified anhydrous gypsum.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions to solve the technical problems:

[0007] In the first aspect, the present invention provides a preparation method of a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration waste gas, and the preparation method includes the following steps:

[0008] S1. Modify mesoporous silica-based molecular sieve with tetraethylenepentamine and organic acid in sequence to obtain material A;

[0009] S2. Acidify the clay mineral powder first, and then amino-functionalize it with a silane coupling agent to obtain Material B;

[0010] S3. Modify anhydrous gypsum with octadecyl hydroxy sulfobetaine to obtain Material C;

[0011] S4. By mass, mix 30 - 35 parts of Material A, 40 - 50 parts of Material B, and 18 - 23 parts of Material C, and ball-mill at a rate of 200 - 400 r / min for 2 - 4 h to obtain the adsorbent.

[0012] In some embodiments, in step S1, the preparation of Material A includes the following steps:

[0013] Mix mesoporous silica-based molecular sieve, tetraethylenepentamine, and water at a feeding ratio of 1 g : (6 - 10) mL : (25 - 35) mL, reflux at 90 - 110 °C for 7 - 9 h. After completion, filter, wash, and dry, then add to water and reflux. Add a 23 - 27 wt% organic acid solution, and simultaneously adjust the pH to 8 - 9, react for 1 - 3 h. After completion, filter, wash, and dry to obtain Material A.

[0014] Preferably, the organic acid is citric acid.

[0015] In some embodiments, in step S2, the preparation of Material B includes the following steps:

[0016] (1) Add the clay mineral powder to a 6 mol / L hydrochloric acid solution, stir and react in a water bath at 75 - 85 °C for 2 - 4 h. After completion, centrifuge, wash the precipitate until it is neutral, dry, grind, and pass through a 100-mesh sieve to obtain acidified clay mineral;

[0017] (2) Disperse the acidified clay mineral in an organic solvent, add N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and react in a constant-temperature water bath at 75 - 85 °C for 32 - 38 h under nitrogen protection. Filter, wash, and dry to obtain amino-functionalized clay mineral, which is Material B.

[0018] In some embodiments, the material ratio of the acidified clay mineral to N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is 1:1.

[0019] In some embodiments, in step S2, the clay mineral powder is a mixture of palygorskite, illite, and chlorite, and the mass ratio of palygorskite, illite, and chlorite is (22 - 27) : (6 - 10) : (10 - 15).

[0020] In some embodiments, the mass ratio of palygorskite, illite, and chlorite is 25:8:12.

[0021] In some of these embodiments, in step S3, the preparation of the material C includes the following steps:

[0022] Add octadecyl hydroxysulfobetaine to anhydrous ethanol and stir to dissolve it. Then add anhydrous gypsum and stir and reflux at 60 - 70 °C for 3 - 5 h. Subsequently, remove the anhydrous ethanol and dry to constant weight to obtain modified anhydrous gypsum, which is the material C.

[0023] In some of these embodiments, the feeding ratio of octadecyl hydroxysulfobetaine, anhydrous ethanol, and anhydrous gypsum is (2 - 4):(22 - 27):1.

[0024] In some of these embodiments, the mesoporous silica-based molecular sieve is molecular sieve SBA-15.

[0025] In a second aspect, a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration flue gas prepared by the above preparation method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention modifies the mesoporous silica-based molecular sieve with tetraethylenepentamine and organic acid in sequence, enhancing the complexation ability with heavy metals. At the same time, the clay mineral powder mixed with palygorskite, illite, and chlorite is first acidified and then aminated with a silane coupling agent to further improve the adsorption ability for dioxins and heavy metals. Meanwhile, octadecyl hydroxysulfobetaine is used to modify anhydrous gypsum, making the modified anhydrous gypsum have both hydrophobic and hydrophilic properties, effectively adsorbing dioxins and heavy metals.

[0028] The adsorbent of the present invention can stably and effectively adsorb dioxins and heavy metals in waste incineration flue gas, has multifunctionality, realizes the synchronous removal of multiple pollutants, and also provides a new idea for the adsorbent of domestic waste incineration flue gas. Detailed implementation manners

[0029] The following combines specific embodiments to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0031] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0032] In the present invention, unless otherwise specified, the test methods used are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained commercially.

[0033] Example 1

[0034] A preparation method of a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration exhaust gas, the preparation method comprising the following steps:

[0035] 1. Add molecular sieve SBA-15, tetraethylenepentamine, and deionized water into a three-necked flask according to a feeding ratio of 1 g: 8 mL: 30 mL, reflux (about 100 °C) for 8 h, then cool, filter, and wash until neutral, and vacuum dry at 70 °C for 12 h.

[0036] 2. Take 5 g of the molecular sieve dried in step 1 and add it to 100 mL of deionized water and reflux (about 100 °C), then add 100 mL of a citric acid solution with a mass fraction of 25% within 1 h, and at the same time add sodium bicarbonate to maintain the pH of the reaction mixture at 9, continue the reaction for 2 h, cool and filter after the reaction, wash with deionized water until neutral, and vacuum dry at 70 °C for 12 h to obtain a modified molecular sieve.

[0037] 3. Weigh 50 g of clay mineral powder and add it to 200 mL of 6 mol / L hydrochloric acid solution, stir and react in a water bath at 80 °C for 3 h, and the stirring rate is 300 rpm. After the reaction, centrifuge, wash the precipitate with deionized water until the pH is neutral, and then dry to constant weight to obtain acidified clay mineral.

[0038] 4. Disperse 10 g of acidified clay mineral in 250 mL of methanol solution, add 10 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane under stirring, and react in a constant temperature water bath at 80 °C for 35 h under nitrogen protection. Filter, wash, and dry the above reaction solution to obtain amino-functionalized clay mineral.

[0039] The clay mineral powder is a mixture of palygorskite, illite and chlorite. The mass ratio of palygorskite, illite and chlorite is 25:8:12. After mixing, the palygorskite, illite and chlorite are pulverized and sieved through a 200-mesh sieve.

[0040] 5. Add octadecyl hydroxy propyl sulfobetaine (DHSB) to absolute ethanol, stir to dissolve, then add anhydrous gypsum and stir and reflux at 65 °C for 4 h. Subsequently, heat up to remove absolute ethanol and dry to constant weight to obtain modified anhydrous gypsum. The feeding ratio of octadecyl hydroxy propyl sulfobetaine, absolute ethanol and anhydrous gypsum is 4 g:25 mL:1 g.

[0041] 6. By mass, mix 32 parts of modified molecular sieve, 45 parts of aminated clay mineral and 20 parts of modified anhydrous gypsum to obtain an abrasive. Add the abrasive, absolute ethanol and zirconia beads to a ball mill at a ratio of 1 g:2 mL:10 g and carry out wet grinding. When grinding, select zirconia beads with a Mohs hardness of 9 (diameter 20 mm) and grind at a rate of 300 r / min for 3 h to obtain an adsorbent.

[0042] Example 2

[0043] A preparation method of a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration flue gas, the preparation method comprising the following steps:

[0044] 1. Add molecular sieve SBA-15, tetraethylenepentamine and deionized water to a three-necked flask at a feeding ratio of 1 g:10 mL:35 mL and reflux (about 100 °C) for 7 h. After completion, cool, filter and wash to neutral, and vacuum dry at 70 °C for 12 h.

[0045] 2. Take 5 g of the molecular sieve dried in step 1 and add it to 100 mL of deionized water and reflux (about 100 °C), then add 100 mL of a citric acid solution with a mass fraction of 23% within 1 h, and at the same time add sodium bicarbonate to maintain the pH of the reaction mixture at 8, and continue the reaction for 3 h. After completion of the reaction, cool, filter, wash with deionized water to neutral, and vacuum dry at 70 °C for 12 h to obtain a modified molecular sieve.

[0046] 3. Weigh 50 g of clay mineral powder and add it to 200 mL of 6 mol / L hydrochloric acid solution, stir and react in a water bath at 85 °C for 4 h, and the stirring rate is 300 rpm. After completion of the reaction, centrifuge, wash the precipitate with deionized water to neutral pH, then dry to constant weight at 80 °C, grind and sieve through a 100-mesh sieve to obtain acidified clay mineral.

[0047] 4. Disperse 10 g of acidified clay minerals in 250 mL of methanol solution, add 10 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane under stirring, and react in a constant temperature water bath at 85 °C for 32 h under nitrogen protection. Filter, wash, and dry the above reaction solution to obtain amino-functionalized clay minerals.

[0048] The clay mineral powder is a mixture of palygorskite, illite, and chlorite. The mass ratio of palygorskite, illite, and chlorite is 27:6:10. After mixing palygorskite, illite, and chlorite, they are pulverized and passed through a 200-mesh sieve.

[0049] 5. Add octadecyl hydroxy propyl sulfobetaine (DHSB) to absolute ethanol, stir to dissolve, then add anhydrous gypsum and stir and reflux at 60 °C for 5 h. Subsequently, heat up to remove absolute ethanol and dry to constant weight to obtain modified anhydrous gypsum. The feeding ratio of octadecyl hydroxy propyl sulfobetaine, absolute ethanol, and anhydrous gypsum is 2 g:27 mL:1 g.

[0050] 6. By mass, mix 30 parts of modified molecular sieve, 50 parts of amino-functionalized clay minerals, and 18 parts of modified anhydrous gypsum to obtain an abrasive. Add the abrasive, absolute ethanol, and zirconia beads to a ball mill according to the ratio of 1 g:2 mL:10 g and perform wet grinding. When grinding, select zirconia beads with a Mohs hardness of 9 (diameter 20 mm) and ball mill at a rate of 200 r / min for 4 h to obtain an adsorbent.

[0051] Example 3

[0052] A preparation method of a high-efficiency adsorbent for dioxins and heavy metals in domestic waste incineration flue gas, the preparation method comprising the following steps:

[0053] 1. Add molecular sieve SBA-15, tetraethylenepentamine, and deionized water to a three-necked flask according to a feeding ratio of 1 g:10 mL:35 mL and reflux (about 100 °C) for 9 h. After completion, cool, filter, and wash until neutral, and vacuum dry at 70 °C for 12 h.

[0054] 2. Take 5 g of the molecular sieve dried in step 1 and add it to 100 mL of deionized water and reflux (about 100 °C), then add 100 mL of a citric acid solution with a mass fraction of 27% within 1 h, and at the same time add sodium bicarbonate to maintain the pH of the reaction mixture at 9, and continue to react for 1 h. After the reaction is completed, cool, filter, wash with deionized water until neutral, and vacuum dry at 70 °C for 12 h to obtain a modified molecular sieve.

[0055] 3. Weigh 50 g of clay mineral powder and add it to 200 mL of 6 mol / L hydrochloric acid solution. Stir and react in a water bath at 75 °C for 2 h, with a stirring rate of 300 rpm. After the reaction, centrifuge, wash the precipitate with deionized water until the pH is neutral, then dry at 80 °C to constant weight, grind through a 100-mesh sieve to obtain acidified clay mineral.

[0056] 4. Disperse 10 g of acidified clay mineral in 250 mL of methanol solution. Add 10 mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane under stirring. React in a constant-temperature water bath at 75 °C for 38 h under nitrogen protection. Filter, wash, and dry the above reaction solution to obtain amino-functionalized clay mineral.

[0057] The clay mineral powder is a mixture of palygorskite, illite, and chlorite. The mass ratio of palygorskite, illite, and chlorite is 22:10:15. After mixing palygorskite, illite, and chlorite, crush them through a 200-mesh sieve.

[0058] 5. Add octadecyl hydroxy propyl sulfobetaine (DHSB) to absolute ethanol, stir to dissolve, then add anhydrous gypsum and stir and reflux at 70 °C for 3 h. Subsequently, heat up to remove absolute ethanol and dry to constant weight to obtain modified anhydrous gypsum. The feeding ratio of octadecyl hydroxy propyl sulfobetaine, absolute ethanol, and anhydrous gypsum is 4 g:22 mL:1 g.

[0059] 6. By mass, mix 35 parts of modified molecular sieve, 40 parts of amino-functionalized clay mineral, and 23 parts of modified anhydrous gypsum to obtain an abrasive. Add the abrasive, absolute ethanol, and zirconia beads to a ball mill in a ratio of 1 g:2 mL:10 g and perform wet grinding. When grinding, select zirconia beads with a Mohs hardness of 9 (diameter 20 mm) and grind at a rate of 400 r / min for 2 h to obtain an adsorbent.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, an equal amount of molecular sieve SBA-15 is used to replace the modified molecular sieve, and the others are the same.

[0062] Comparative Example 2

[0063] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the modified molecular sieve is not added, and the others are the same.

[0064] Comparative Example 3

[0065] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, an equal amount of montmorillonite powder is used to replace the amino-functionalized clay mineral, and the others are the same.

[0066] Comparative Example 4

[0067] The difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, an equal amount of clay mineral powder is used to replace the aminated clay mineral, and the others are the same.

[0068] The clay mineral powder is a mixture of palygorskite, illite and chlorite. The mass ratio of palygorskite, illite and chlorite is 25:8:12. After mixing, the palygorskite, illite and chlorite are pulverized and sieved through a 200-mesh sieve.

[0069] Test Example 1

[0070] The adsorbents prepared in Examples 1-3 and Comparative Examples 1-4 were used to adsorb and treat the flue gas containing dioxin and heavy metal gases, as follows:

[0071] In a domestic waste incineration plant, the waste gas was purified by the method of "SNCR + semi-dry desulfurization + flue duct silicon-based adsorbent injection + bag filter". The adsorbents prepared in Examples 1-3 and Comparative Examples 1-4 were respectively put in at a rate of 0.5 kg / t of waste. The incineration treatment capacity was 500 t / d. Before and after the waste gas purification treatment, dioxin and heavy metals were detected respectively according to the method of GB 18485-2014 "Pollution Control Standards for Domestic Waste Incineration". The test was repeated three times. Then, according to the concentrations before and after the treatment, the removal rates of the adsorbent for dioxin and heavy metals were calculated. The adsorption test results are shown in Tables 1-4 below.

[0072] Table 1 Dioxin Adsorption Test Results

[0073]

[0074]

[0075] Table 2 Mercury and Its Compounds Adsorption Test Results

[0076]

[0077] Note: "ND" means less than the detection limit or not detected.

[0078] Table 3 Cadmium / Thallium and Their Compounds Adsorption Test Results

[0079]

[0080]

[0081] Note: "ND" means less than the detection limit or not detected.

[0082] Table 4 Antimony / Arsenic / Lead / Chromium / Copper / Cobalt / Manganese / Nickel and Their Compounds Adsorption Test Results

[0083]

[0084] As can be seen from Table 1-4, compared with Comparative Examples 1-4, the adsorbents prepared in Examples 1-3 have better adsorption effects on dioxins and heavy metals in waste incineration flue gas; comparing Comparative Examples 1, 2 and Example 1, when the ordinary molecular sieve is replaced or the modified molecular sieve is not added, the removal rates of dioxins and heavy metals of the prepared adsorbent are significantly lower than those of the adsorbent in Example 1, indicating that the modification of mesoporous silica-based molecular sieve with tetraethylenepentamine and citric acid can improve the adsorption efficiency of dioxins and heavy metals; then, by comparing Comparative Examples 3, 4 and Example 1, it can be seen that the adsorbents added with ordinary montmorillonite or unaminated clay mineral mixture powder have lower removal rates of dioxins and heavy metals, indicating that under the action of each component of the adsorbent of the present invention, replacing or reducing any component will affect the balance of the adsorbent system and thus affect the adsorption effect.

[0085] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of an efficient adsorbent for dioxin and heavy metals in the waste gas from municipal solid waste incineration, characterized in that, The preparation method includes the following steps: S1. Modify mesoporous silica-based molecular sieve with tetraethylenepentamine and organic acid in sequence to obtain material A; S2. Acidify clay mineral powder first, and then aminize it with silane coupling agent to obtain material B; S3. Modify anhydrous gypsum with octadecyl hydroxy sulfobetaine to obtain material C; S4. Mix 30 - 35 parts by mass of material A, 40 - 50 parts by mass of material B, and 18 - 23 parts by mass of material C, and ball mill at a rate of 200 - 400 r / min for 2 - 4 h to obtain the adsorbent.

2. The preparation method according to claim 1, characterized in that, In step S1, the preparation of material A includes the following steps: Mix mesoporous silica-based molecular sieve, tetraethylenepentamine, and water at a feeding ratio of 1 g:(6 - 10) mL:(25 - 35) mL, reflux at 90 - 110 °C for 7 - 9 h. After completion, filter, wash, and dry, then add to water and reflux, add 23 - 27 wt% organic acid solution, and adjust the pH to 8 - 9 simultaneously, react for 1 - 3 h. After completion, filter, wash, and dry to obtain material A.

3. The preparation method according to claim 1, wherein In step S2, the preparation of material B includes the following steps: (1) Add clay mineral powder to 6 mol / L hydrochloric acid solution, stir and react in a water bath at 75 - 85 °C for 2 - 4 h. After completion, centrifuge, wash the precipitate until it is neutral, dry, grind, and pass through a 100-mesh sieve to obtain acidified clay mineral; (2) Disperse the acidified clay mineral in an organic solvent, add N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and react in a constant-temperature water bath at 75 - 85 °C for 32 - 38 h under nitrogen protection. Filter, wash, and dry to obtain material B.

4. The preparation method according to claim 3, characterized in that, The feed liquid ratio of the acidified clay mineral to N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is 1:

1.

5. The preparation method according to claim 1, characterized in that, In step S2, the clay mineral powder is a mixture of palygorskite, illite, and chlorite, and the mass ratio of palygorskite, illite, and chlorite is (22 - 27):(6 - 10):(10 - 15).

6. The preparation method according to claim 5, wherein The mass ratio of palygorskite, illite, and chlorite is 25:8:

12.

7. The preparation method according to claim 1, wherein In step S3, the preparation of material C includes the following steps: Add octadecyl hydroxy sulfobetaine to absolute ethanol and stir to dissolve, then add anhydrous gypsum and stir and reflux at 60 - 70 °C for 3 - 5 h. Subsequently, remove absolute ethanol and dry to constant weight to obtain material C.

8. The preparation method according to claim 7, characterized in that, The feeding ratio of octadecyl hydroxy sulfobetaine, absolute ethanol, and anhydrous gypsum is (2 - 4):(22 - 27):

1.

9. The preparation method according to claim 1, characterized in that, The mesoporous silica-based molecular sieve is molecular sieve SBA-15.

10. A high-efficiency adsorbent for dioxin and heavy metals in domestic waste incineration flue gas prepared by the preparation method according to any one of claims 1 - 9.

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