A heavy metal treatment agent for sludge and preparation method thereof

Abstract

The invention discloses a heavy metal treatment agent for sludge and a preparation method thereof, and belongs to the technical field of sludge treatment. 90-100 parts of inorganic filler, 3-6 parts of vulcanizing agent, 0.5-2.5 parts of chelating agent, 0.8-4 parts of modified flocculant, and 0.5-2 parts of amide compound are weighed by weight and placed in a stirrer and stirred until uniformly mixed to obtain a heavy metal treatment agent for sludge. The modified flocculant of the present invention contains polyacrylamide flocculant, isothiazolinone structure and dimethyl hydantoin structure, the polyacrylamide flocculant gives the modified flocculant the effect of fixing heavy metals, the isothiazolinone structure and the dimethyl hydantoin structure work synergistically, giving the modified flocculant excellent and stable antibacterial effect, therefore, the heavy metal treatment agent for sludge of the present invention has the dual effects of reducing heavy metal content and antibacterial.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment, and in particular relates to a heavy metal treatment agent for sludge and a preparation method thereof. Background Art

[0002] The sludge produced by my country's sewage treatment plants contains high levels of heavy metals, especially Pb, Zn, Cu, Mn and other elements in the sludge often exceed the standard. If no harmless treatment is carried out and it is piled up in the open air, it will not only affect the utilization of the sludge, but also cause secondary pollution due to the leaching of heavy metals in the sludge, endangering the safety of humans and other organisms. The methods for treating heavy metals in sludge include electrochemical method, freeze-thaw method, solidification method, chemical extraction method, etc. At present, the solidification method is widely used at home and abroad because it has the advantages of simple operation, obvious effect and low secondary pollution.

[0003] In addition, although the heavy metal content of sludge has been effectively reduced after heavy metal treatment, pathogenic bacteria and other microorganisms may still exist in the sludge, which pose a potential threat to the environment and human health, and also produce odors, affecting the ecological environment. Therefore, it is very necessary to carry out antibacterial treatment on sludge. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a heavy metal treatment agent for sludge and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A heavy metal treatment agent for sludge comprises the following raw materials in parts by weight: 90-100 parts of inorganic filler, 3-6 parts of sulfiding agent, 0.5-2.5 parts of chelating agent, 0.8-4 parts of modified flocculant and 0.5-2 parts of amide compound.

[0007] Furthermore, the inorganic filler is one or more of hydroxyapatite, bentonite, calcium peroxide, calcium oxide, calcium hydroxide, and phosphate rock.

[0008] Furthermore, the vulcanizing agent is one or more of sodium sulfide, calcium sulfide, potassium sulfide, and sodium thiosulfate.

[0009] Furthermore, the chelating agent is one or both of ethylenediaminetetraacetic acid and sodium ethylenediaminetetraacetate.

[0010] Furthermore, the modified flocculant is prepared by the following steps:

[0011] S1. A dry four-necked flask was purged with nitrogen for 30 minutes to exclude air and moisture, and then 4-penten-1-ol, vinyltrimethoxysilane, tetraisopropyl titanate and toluene were added to the flask, stirred thoroughly, heated to 90°C for reaction for 18 hours, cooled to room temperature after the reaction, distilled under reduced pressure, washed with anhydrous ethanol for 3 times, and dried at 80°C for 12 hours. The whole process was carried out under nitrogen protection to obtain intermediate 1; the amount ratio of 4-penten-1-ol, vinyltrimethoxysilane, tetraisopropyl titanate and toluene was 9.9 mL:13.8 mL:0.08 mL:140 mL;

[0012] The molar ratio of vinyltrimethoxysilane to 4-penten-1-ol is controlled to be 1:1 and 4-penten-1-ol is slightly excessive. The silaneoxy group of vinyltrimethoxysilane and the hydroxyl group of 4-penten-1-ol undergo the following chemical reaction under the action of the catalyst tetraisopropyl titanate. The reaction process is shown below:

[0013]

[0014] S2, nitrogen was blown into a dry four-necked flask for 30 minutes to expel air and moisture in the flask, then isothiazolinone, 3-amino-1-propanol and chloroform were added, mixed evenly, and then pyridine was slowly added, the temperature was raised to 60°C and stirred for reaction for 2 hours, and after the reaction was completed, it was cooled to room temperature and then distilled under reduced pressure to obtain intermediate 2; the amount ratio of isothiazolinone, 3-amino-1-propanol, pyridine and chloroform was 10.8mL:7.5mL:8.7mL:130mL;

[0015] The molar ratio of isothiazolinone and 3-amino-1-propanol is controlled to be 1:1 and 3-amino-1-propanol is slightly excessive. Under heating, -Cl of isothiazolinone and -NH2 of 3-amino-1-propanol undergo nucleophilic substitution reaction, and pyridine is used as an acid-binding agent. The reaction process is as follows:

[0016]

[0017] S3, nitrogen was blown into a dry four-necked flask for 30 minutes to exclude air and moisture, and then intermediate 1, intermediate 2, tetraisopropyl titanate and DMSO (dimethyl sulfoxide) were added, and the mixture was heated to 100°C for reaction for 24 hours after being fully stirred. After the reaction, the mixture was cooled to room temperature, distilled under reduced pressure, washed with anhydrous ethanol for 3 times, and dried at 80°C for 12 hours. The whole process was carried out under nitrogen protection to obtain intermediate 3; the amount ratio of intermediate 1, intermediate 2, tetraisopropyl titanate and DMSO was 16.2g:16.3g:0.07mL:130mL;

[0018] Under the action of the catalyst tetraisopropyl titanate, the molar ratio of intermediate 1 to intermediate 2 is controlled to be 1:1.05-1.1, and the silanol group of intermediate 1 and the hydroxyl group of intermediate 2 undergo the following chemical reaction, and the reaction process is as follows:

[0019]

[0020] S4, after nitrogen replaces the air in the dry four-necked flask, add intermediate 3, 1,3-dihydroxymethyl-5,5-dimethylhydantoin, tetraisopropyl titanate and DMSO, stir and dissolve, heat to 100°C, keep warm for 24 hours, cool to room temperature after the reaction, distill under reduced pressure, wash with anhydrous ethanol 3 times, dry at 80°C for 12 hours, and the whole process is carried out under nitrogen protection to obtain intermediate 4; the amount ratio of intermediate 3, 1,3-dihydroxymethyl-5,5-dimethylhydantoin, tetraisopropyl titanate and DMSO is 25.1g:14.4g:0.06mL:120mL;

[0021] Under the action of the catalyst tetraisopropyl titanate, the molar ratio of intermediate 3 and 1,3-dihydroxymethyl-5,5-dimethylhydantoin is controlled to be 1:1.05-1.1, and the silanoloxy group of intermediate 3 and the hydroxyl group of 1,3-dihydroxymethyl-5,5-dimethylhydantoin undergo the following chemical reaction. The reaction process is shown below:

[0022]

[0023] S5. Add intermediate 4, acrylamide, disodium ethylenediaminetetraacetate and DMF (N,N-dimethylformamide) to a dry four-necked round-bottom flask, stir to form a uniform solution, adjust the pH to 4 with 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide, pass nitrogen into the reaction system for 30 minutes to exhaust the air in the system, add ammonium persulfate and azobisisobutyronitrile, heat to 60°C and stir for 3 hours, wash with anhydrous ethanol 5 times after the reaction, and dry at 60°C for 24 hours to obtain a modified flocculant. The amount ratio of acrylamide, intermediate 4, disodium ethylenediaminetetraacetate, ammonium persulfate, azobisisobutyronitrile and DMF is 5g:10.3g:0.076g:0.003g:0.0038g:140mL.

[0024] Under the action of initiators ammonium persulfate and azobisisobutyronitrile, the carbon-carbon double bond at the end of intermediate 4 can react chemically with the carbon-carbon double bond of acrylamide, and intermediate 4 is grafted onto the macromolecular chain of polyacrylamide flocculant to obtain a modified flocculant.

[0025] Intermediate 4 contains isothiazolinone antibacterial structure and dimethyl hydantoin antibacterial structure. Isothiazolinone works by breaking the bond between bacteria and algae proteins. After contacting with microorganisms, it can quickly and irreversibly inhibit the growth of microorganisms, thereby causing the death of microbial cells. It has a strong inhibitory and killing effect on common bacteria, fungi, algae, etc., and has the characteristics of high killing efficiency, good degradability, no residue, safe operation, good compatibility, strong stability, low use cost, etc., and is easily biodegraded into non-toxic and non-polluting substances. In addition, isothiazolinone has good miscibility and can be miscible with most anionic, cationic and non-ionic surfactants. Dimethyl hydantoin is a broad-spectrum, efficient antibacterial preservative that can effectively resist Gram-positive bacteria, Gram-negative bacteria, molds, etc., and can remain stable when used in a wide pH value and temperature range. Since intermediate 4 can stably exist in the modified flocculant and can play its role for a long time, the isothiazolinone structure and dimethyl hydantoin structure on the modified flocculant work synergistically to give the heavy metal treatment agent for sludge excellent and stable antibacterial activity, thereby making it difficult for sludge to produce bacteria and reducing odor.

[0026] Polyacrylamide flocculants can combine with heavy metals to form a combination with heavy metal ions as central ions and organic active groups as ligands, or a combination of sulfur ions and heavy metals to form an organic combination state that is insoluble in water, thereby fixing heavy metals.

[0027] Therefore, the modified flocculant of the present invention not only has excellent and stable antibacterial activity, but also has the function of fixing heavy metals. Thus, the heavy metal treatment agent for sludge of the present invention can not only fix heavy metals and reduce the heavy metal content, but also has antibacterial effect, and has a dual effect.

[0028] Furthermore, the amide compound is one or more of carbonamide, carbonyl diamide, and aminoformamide.

[0029] A method for preparing a heavy metal treatment agent for sludge comprises the following steps:

[0030] Weigh each raw material by weight and place it in a stirrer and stir until it is evenly mixed to obtain a heavy metal treatment agent for sludge.

[0031] Beneficial effects of the present invention: the modified flocculant of the present invention contains polyacrylamide flocculant, isothiazolinone structure and dimethyl hydantoin structure; the polyacrylamide flocculant gives the modified flocculant the function of fixing heavy metals; the isothiazolinone structure and the dimethyl hydantoin structure work synergistically to give the modified flocculant excellent and stable antibacterial effect; therefore, the heavy metal treatment agent for sludge of the present invention has the dual functions of reducing heavy metal content and antibacterial. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] The specific steps for preparing the modified flocculant are as follows:

[0035] S1. A 250 mL dry four-necked flask was purged with nitrogen for 30 min to exclude air and moisture, and then 9.9 mL of 4-penten-1-ol, 13.8 mL of vinyltrimethoxysilane, 0.08 mL of tetraisopropyl titanate and 140 mL of toluene were added to the flask. After sufficient stirring, the temperature was raised to 90 ° C for reaction for 18 h. After the reaction was completed, it was cooled to room temperature, distilled under reduced pressure, washed with anhydrous ethanol for 3 times, and dried at 80 ° C for 12 h. The whole process was carried out under nitrogen protection to obtain intermediate 1;

[0036] S2, nitrogen was blown into a 250 mL dry four-necked flask for 30 min to expel air and moisture in the flask, then 10.8 mL of isothiazolinone, 7.5 mL of 3-amino-1-propanol and 130 mL of chloroform were added, and 8.7 mL of pyridine was slowly added after mixing evenly, and the temperature was raised to 60 ° C and stirred for 2 h. After the reaction was completed, it was cooled to room temperature and then distilled under reduced pressure to obtain intermediate 2;

[0037] S3, nitrogen was blown into a 250mL dry four-necked flask for 30min to exclude air and moisture, and then 16.2g of intermediate 1, 16.3g of intermediate 2, 0.07mL of tetraisopropyl titanate and 130mL of DMSO were added, and the mixture was stirred thoroughly and heated to 100°C for reaction for 24h. After the reaction, the mixture was cooled to room temperature, distilled under reduced pressure, washed with anhydrous ethanol for 3 times, and dried at 80°C for 12h. The whole process was carried out under nitrogen protection to obtain intermediate 3;

[0038] S4, after replacing the air in a 250mL dry four-necked flask with nitrogen, add 25.1g of intermediate 3, 14.4g of 1,3-dihydroxymethyl-5,5-dimethylhydantoin, 0.06mL of tetraisopropyl titanate and 120mL of DMSO, stir and dissolve, heat to 100°C, keep warm and react for 24h, cool to room temperature after the reaction, distill under reduced pressure, wash with anhydrous ethanol 3 times, dry at 80°C for 12h, and the whole process is carried out under nitrogen protection to obtain intermediate 4;

[0039] S5. Add 10.3g of intermediate 4, 5g of acrylamide, 0.076g of disodium ethylenediaminetetraacetate and 140mL of DMF into a 250mL dry four-necked round-bottom flask, stir to form a uniform solution, adjust the pH to 4 with 0.1mol / L hydrochloric acid and 0.1mol / L sodium hydroxide, pass nitrogen into the reaction system for 30min to expel the air in the system, add 0.003g of ammonium persulfate and 0.0038g of azobisisobutyronitrile, heat to 60℃ and stir for 3h, wash with anhydrous ethanol 5 times after the reaction, and dry at 60℃ for 24h to obtain a modified flocculant.

[0040] Example 2

[0041] The specific steps for preparing heavy metal treatment agent for sludge are as follows:

[0042] Weigh 50 parts of hydroxyapatite, 6 parts of bentonite, 20 parts of calcium oxide, 14 parts of calcium hydroxide, 3 parts of potassium sulfide, 0.5 parts of ethylenediaminetetraacetic acid, 0.8 parts of the modified flocculant prepared in Example 1, and 0.5 parts of carbonamide by weight, place them in a stirrer and stir until they are evenly mixed to obtain a heavy metal treatment agent for sludge.

[0043] Example 3

[0044] The specific steps for preparing heavy metal treatment agent for sludge are as follows:

[0045] Weigh 48 parts of hydroxyapatite, 6 parts of bentonite, 10 parts of calcium peroxide, 20 parts of calcium oxide, 14 parts of calcium hydroxide, 5 parts of calcium sulfide, 2 parts of sodium ethylenediaminetetraacetate, 2 parts of the modified flocculant prepared in Example 1, and 1.5 parts of aminoformamide by weight, place them in a stirrer and stir until they are evenly mixed to obtain a heavy metal treatment agent for sludge.

[0046] Example 4

[0047] The specific steps for preparing heavy metal treatment agent for sludge are as follows:

[0048] Weigh 30 parts of hydroxyapatite, 6 parts of calcium peroxide, 20 parts of calcium oxide, 14 parts of calcium hydroxide, 30 parts of phosphate rock, 3 parts of sodium sulfide, 3 parts of sodium thiosulfate, 2.5 parts of sodium ethylenediaminetetraacetate, 4 parts of the modified flocculant prepared in Example 1, and 2 parts of carbodiamide in a stirrer and stir until mixed evenly to obtain a heavy metal treatment agent for sludge.

[0049] Comparative Example 1

[0050] The specific steps for preparing heavy metal treatment agent for sludge are as follows:

[0051] The remaining steps remain unchanged, except that the modified flocculant in Example 2 is replaced by an untreated polyacrylamide flocculant to obtain a heavy metal treatment agent for sludge.

[0052] Comparative Example 2

[0053] The specific steps for preparing heavy metal treatment agent for sludge are as follows:

[0054] The remaining steps remain unchanged, and only the modified flocculant of Example 2 is removed to obtain a heavy metal treatment agent for sludge.

[0055] Performance Testing

[0056] 2.5 g of the heavy metal treatment agent for sludge prepared in Examples 2-4 and Comparative Examples 1-2 and 50 g of sludge were placed in a stirrer and stirred thoroughly until they were evenly mixed. The sludge was then spread out and naturally air-dried at room temperature for curing. After 2 days, the heavy metal content of the leachate was measured using an atomic absorption spectrophotometer according to the toxic leaching of solid waste (TCLP) method of the U.S. Environmental Protection Agency. The test results are shown in Table 1 below:

[0057] Table 1

[0058]

[0059] Antibacterial test: Add 20 mL of agar medium (add 3.2 g of nutrient agar to every 100 mL of deionized water to prepare the agar solution, shake well and put it in an autoclave for sterilization, wait until the temperature in the autoclave drops to 60°C, take it out for use) and 0.1 mL of Escherichia coli suspension (Escherichia coli 35218: from China Microbiological Culture Collection Center, 6×105 CFU / mL) to a sterile culture dish, shake well, and add 70 mL of phosphate buffered saline (weigh 8.0 g of sodium chloride, 1.44 g of Disodium hydrogen phosphate and 0.24g potassium dihydrogen phosphate were dissolved in 800mL distilled water, and the pH value of the solution was adjusted to 7.4 with hydrochloric acid. Finally, distilled water was added to make the volume 1L to obtain a 0.01mol / L phosphate buffered saline solution). The heavy metal treatment agent for sludge prepared in Example 2-4 and Comparative Example 1-2 was added to a culture dish, and each group of culture dishes was placed in a constant temperature and humidity incubator (temperature of 37°C, relative humidity greater than 90%), and cultured at 37°C for 24h and 60 days, and then the antibacterial rate was calculated. The test results are shown in Table 2 below:

[0060] Table 2

[0061]

[0062] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A heavy metal treatment agent for sludge, characterized in that: The raw materials include the following parts by weight: 90-100 parts of inorganic filler, 3-6 parts of vulcanizing agent, 0.5-2.5 parts of chelating agent, 0.8-4 parts of modified flocculant, and 0.5-2 parts of amide compound; Wherein, the modified flocculant is prepared by the following steps: S1. After nitrogen is blown into the flask, 4-penten-1-ol, vinyltrimethoxysilane, tetraisopropyl titanate and toluene are added, the mixture is stirred and heated to 90°C for reaction for 18 hours, cooled, distilled under reduced pressure, washed and dried to obtain intermediate 1; the dosage ratio of 4-penten-1-ol, vinyltrimethoxysilane, tetraisopropyl titanate and toluene is 9.9 mL:13.8 mL:0.08 mL:140 mL; S2. After nitrogen is blown into the flask, isothiazolinone, 3-amino-1-propanol and chloroform are added, mixed, pyridine is added, reacted at 60° C. for 2 h, cooled, and distilled under reduced pressure to obtain intermediate 2; the dosage ratio of isothiazolinone, 3-amino-1-propanol, pyridine and chloroform is 10.8 mL: 7.5 mL: 8.7 mL: 130 mL; S3, after nitrogen blowing into the flask, add intermediate 1, intermediate 2, tetraisopropyl titanate and DMSO, react at 100°C for 24h, cool, distill under reduced pressure, wash, and dry to obtain intermediate 3; the amount ratio of intermediate 1, intermediate 2, tetraisopropyl titanate and DMSO is 16.2g:16.3g:0.07mL:130mL; S4, after replacing the air in the bottle with nitrogen, add intermediate 3, 1,3-dihydroxymethyl-5,5-dimethylhydantoin, tetraisopropyl titanate and DMSO, stir, react at 100°C for 24h, cool, distill under reduced pressure, wash, and dry to obtain intermediate 4; the amount ratio of intermediate 3, 1,3-dihydroxymethyl-5,5-dimethylhydantoin, tetraisopropyl titanate and DMSO is 25.1g:14.4g:0.06mL:120mL; S5. Add intermediate 4, acrylamide, disodium ethylenediaminetetraacetate and DMF into a flask, stir, adjust the pH to 4 with hydrochloric acid and sodium hydroxide, pass nitrogen, add ammonium persulfate and azobisisobutyronitrile, stir at 60°C for 3h, wash, and dry to obtain a modified flocculant; the dosage ratio of acrylamide, intermediate 4, disodium ethylenediaminetetraacetate, ammonium persulfate, azobisisobutyronitrile and DMF is 5g:10.3g:0.076g:0.003g:0.0038g:140mL.

2. A heavy metal treatment agent for sludge according to claim 1, characterized in that: The inorganic filler is one or more of hydroxyapatite, bentonite, calcium peroxide, calcium oxide, calcium hydroxide, and phosphate rock.

3. A heavy metal treatment agent for sludge according to claim 1, characterized in that: The vulcanizing agent is one or more of sodium sulfide, calcium sulfide, potassium sulfide and sodium thiosulfate; the chelating agent is one or two of ethylenediaminetetraacetic acid and sodium ethylenediaminetetraacetate.

4. A heavy metal treatment agent for sludge according to claim 1, characterized in that: The amide compound is one or more of carbonamide, carbonyl diamide and aminoformamide.

5. The method for preparing a heavy metal treatment agent for sludge according to claim 1, characterized in that: The following steps are involved: Weigh each raw material by weight and place it in a stirrer and stir until it is evenly mixed to obtain a heavy metal treatment agent for sludge.

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