CN114906914A - Environment-friendly plant tannin-based flocculant and preparation method thereof - Google Patents
Environment-friendly plant tannin-based flocculant and preparation method thereof Download PDFInfo
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- 239000001648 tannin Substances 0.000 title claims abstract description 113
- 229920001864 tannin Polymers 0.000 title claims abstract description 113
- 235000018553 tannin Nutrition 0.000 title claims abstract description 113
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 11
- 241000196324 Embryophyta Species 0.000 claims description 75
- 239000000243 solution Substances 0.000 claims description 71
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 52
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 44
- 239000007864 aqueous solution Substances 0.000 claims description 28
- 239000004312 hexamethylene tetramine Substances 0.000 claims description 26
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims description 26
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 229910052757 nitrogen Inorganic materials 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 19
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 11
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- 238000001291 vacuum drying Methods 0.000 claims description 8
- 240000006409 Acacia auriculiformis Species 0.000 claims description 7
- 230000002378 acidificating effect Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000007344 nucleophilic reaction Methods 0.000 claims description 3
- 239000008394 flocculating agent Substances 0.000 abstract description 11
- 239000003344 environmental pollutant Substances 0.000 abstract description 7
- 231100000719 pollutant Toxicity 0.000 abstract description 7
- 230000007613 environmental effect Effects 0.000 abstract description 4
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 abstract description 3
- 230000003311 flocculating effect Effects 0.000 abstract 1
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 15
- 241000246150 Cercis Species 0.000 description 14
- 235000006228 Cercis occidentalis Nutrition 0.000 description 14
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 12
- 230000000694 effects Effects 0.000 description 10
- 238000005189 flocculation Methods 0.000 description 8
- 230000016615 flocculation Effects 0.000 description 8
- 239000005995 Aluminium silicate Substances 0.000 description 7
- 235000012211 aluminium silicate Nutrition 0.000 description 7
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 238000000227 grinding Methods 0.000 description 6
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- 238000012360 testing method Methods 0.000 description 5
- 125000002091 cationic group Chemical group 0.000 description 4
- 230000018044 dehydration Effects 0.000 description 4
- 238000006297 dehydration reaction Methods 0.000 description 4
- 241000220479 Acacia Species 0.000 description 3
- 235000010643 Leucaena leucocephala Nutrition 0.000 description 3
- 238000006683 Mannich reaction Methods 0.000 description 3
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 3
- 235000013311 vegetables Nutrition 0.000 description 3
- 241000993444 Acacia mearnsii Species 0.000 description 2
- 241000588653 Neisseria Species 0.000 description 2
- 241000375392 Tana Species 0.000 description 2
- WGQKYBSKWIADBV-UHFFFAOYSA-N aminomethyl benzene Natural products NCC1=CC=CC=C1 WGQKYBSKWIADBV-UHFFFAOYSA-N 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
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- 125000000879 imine group Chemical group 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
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- 239000010802 sludge Substances 0.000 description 2
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- 238000001228 spectrum Methods 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 229940010048 aluminum sulfate Drugs 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- HGOMLSWXJIICBL-UHFFFAOYSA-F dialuminum;zinc;tetrasulfate;tetracosahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.[Al+3].[Al+3].[Zn+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O HGOMLSWXJIICBL-UHFFFAOYSA-F 0.000 description 1
- 229940032950 ferric sulfate Drugs 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- -1 nitrogen-containing compound Chemical class 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 230000000269 nucleophilic effect Effects 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 150000008442 polyphenolic compounds Chemical class 0.000 description 1
- 235000013824 polyphenols Nutrition 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229930000044 secondary metabolite Natural products 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 229920005613 synthetic organic polymer Polymers 0.000 description 1
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 1
- 229960001763 zinc sulfate Drugs 0.000 description 1
- 229910000368 zinc sulfate Inorganic materials 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
The invention provides an environment-friendly plant tannin-based flocculant and a preparation method thereof. The method does not relate to the use of formaldehyde, has the advantages of environmental friendliness and low cost, and the obtained flocculating agent has a good flocculating effect, can remove a large amount of pollutants such as suspended matters and the like, quickly purifies the water body, and remarkably improves the water quality of the water body.
Description
Technical Field
The invention relates to the technical field of flocculating agents, and particularly relates to an environment-friendly plant tannin-based flocculating agent and a preparation method thereof.
Background
The flocculation precipitation method which is an important component in water treatment engineering has the advantages that the treatment effect depends on the performance of the flocculating agent to a great extent, but the traditional flocculating agents which are generally used at present have different advantages and disadvantages.
Inorganic flocculants (such as ferric sulfate, aluminum sulfate, zinc sulfate, alum and the like) have the characteristics of good flocculation effect, low price and the like, but the residue of inorganic metal ions in water can cause secondary pollution. Wherein, the ferric salt flocculating agent can influence the color of the effluent, and the residual aluminum of the aluminum salt flocculating agent can cause certain harm to human bodies.
Compared with inorganic flocculant, the organic polymer flocculant has the advantages of less dosage, wide application range, less influence by salts and environmental conditions, less sludge, good treatment effect and the like. The synthetic organic polymeric flocculant has the advantages of small dosage, strong flocculation capability, high flocculation speed, small sludge generation amount and the like, but the development of the synthetic organic polymeric flocculant in the aspects of food processing, feedwater treatment and the like is limited by the content of residual monomers in a final product.
Compared with the synthetic organic polymer flocculant, the natural organic polymer flocculant is prepared by chemical modification, and has the outstanding characteristics of wide raw material source, lower cost, no toxicity, easy biodegradation, capability of preparing a multifunctional flocculant and the like. Plant tannin, also called plant polyphenol, is a secondary metabolite of plant complex phenols, and the reserve of plant tannin in nature is very rich, mainly exists in peels, roots, leaves and pulp of plants, and is a fourth forest byproduct second to cellulose, lignin and hemicellulose. The natural extracted plant tannin has a low isoelectric point (pHpzc is 2.0-3.0), and pollutants generated by natural water and human activities are mainly electronegative, so that the plant tannin generally needs to be subjected to cationization modification to be used as a flocculating agent.
At present, the mainstream modification method at home and abroad is to introduce amino into the structure of the plant tannin so as to improve the isoelectric point of the plant tannin. The Mannich reaction can increase the isoelectric point of plant tannin to 7.0-8.0, but the reaction involves adding a nitrogen-containing compound and formaldehyde, and the use of formaldehyde can increase the cost of the flocculant on one hand, and on the other hand, formaldehyde remaining in the final product can cause damage to the environment and risks to human health.
Disclosure of Invention
The invention aims to provide a preparation method of an environment-friendly plant tannin-based flocculant, aiming at the defects of the prior art, the method does not involve the use of formaldehyde, and has the advantages of environmental friendliness and low cost, and the obtained flocculant has a good flocculation effect.
According to the first aspect of the invention, plant tannin and hexamethylenetetramine are put into alkaline condition to react, at the moment, hexamethylenetetramine is decomposed to generate an intermediate aminoimine group, and tannin molecules with nucleophilic reaction sites are specifically combined with the aminoimine group, so that the isoelectric point of the flocculant is improved, and the plant tannin-based flocculant is obtained.
Preferably, the method comprises the following specific steps:
s1, heating the aqueous solution of the plant tannin in a water bath, continuously stirring the aqueous solution of the plant tannin, introducing nitrogen, and adjusting the pH value of the aqueous solution of the plant tannin to be alkaline after the temperature of the aqueous solution of the plant tannin reaches a first temperature interval to obtain a first solution;
s2, keeping the temperature of the first solution in a first temperature interval, keeping stirring and nitrogen introduction of the first solution continuously, dropwise adding a hexamethylenetetramine solution into the first solution under the condition, and after dropwise adding, continuously stirring and introducing nitrogen until the reaction is finished to obtain a second solution;
and S3, drying the second solution after the pH value of the second solution is acidic to obtain the environment-friendly plant tannin-based flocculant.
Preferably, in the water solution of the plant tannin, the mass ratio of the plant tannin to the deionized water is 1 (5-10).
Preferably, the first temperature interval is 80-90 ℃, and the nitrogen flow is 3-5 mL/min.
Preferably, the pH value of the aqueous solution of the plant tannin is adjusted to 10-11 by adopting a sodium hydroxide solution.
Preferably, the concentration of the hexamethylenetetramine solution is 0.1mol/L, and the volume ratio of the plant tannin water solution to the hexamethylenetetramine solution is (2-10): 1.
Preferably, the dropping speed of the hexamethylenetetramine solution is 2-8 mL/min.
Preferably, the pH value of the second solution is adjusted to 2-3 by adopting a hydrochloric acid solution, and then vacuum drying is carried out, wherein the drying temperature is 40-60 ℃.
Preferably, the vegetable tannin is black wattle tannin.
According to a second aspect of the invention, the invention provides an environment-friendly plant tannin-based flocculant, which is prepared by adopting the preparation method of the environment-friendly plant tannin-based flocculant.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the preparation method of the environment-friendly plant tannin-based flocculant, plant tannin and hexamethylenetetramine are placed under an alkaline condition, hexamethylenetetramine can be decomposed in an alkaline solution to generate an amino imine group intermediate, the intermediate has high activity and is easy to react, and a great number of nucleophilic sites are arranged on tannin molecules and can react with the amino imine group to form benzylamine bonds on the tannin molecules.
When the pH of the reaction solution is more than 10, tannin molecules can react with the A ring and the B ring to participate in the reaction to form more benzylamine bonds, so that the isoelectric point of the product is effectively improved, the electrostatic binding capacity of the flocculant and negatively charged pollutants is improved when the flocculant is used, the obtained flocculant has a good flocculation effect, can remove pollutants such as suspended matters in a large amount, quickly purifies a water body, remarkably improves the water quality of the water body, and can be widely applied to flocculation precipitation of sewage treatment.
2. The preparation method of the environment-friendly plant tannin-based flocculant has the advantages of simple preparation process, easiness in operation, no formaldehyde participation in the whole preparation process, environmental friendliness, low cost and suitability for industrial production and application.
Drawings
FIG. 1 is a reaction schematic diagram of a preparation method of the environment-friendly plant tannin-based flocculant of the invention.
FIG. 2 is a ZETA potential diagram of the cation acacia mearnsii tannin and cation acacia mearnsii tannin flocculants of example 1.
FIG. 3 is a FTIR plot of Neisseria tana tannin and cationic Neisseria tana tannin flocculants of example 1.
Detailed Description
In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings.
In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways.
The invention provides a preparation method of an environment-friendly plant tannin-based flocculant aiming at the condition that formaldehyde is needed to participate in a Mannich reaction, and the plant tannin and hexamethylenetetramine are used for preparing a cationic flocculant to replace the Mannich reaction to produce the tannin-based flocculant.
In an exemplary embodiment of the present invention, with reference to fig. 1, a method for preparing an environment-friendly plant tannin-based flocculant is provided, wherein plant tannin and hexamethylenetetramine are subjected to alkaline conditions for reaction, wherein hexamethylenetetramine is decomposed to generate an intermediate aminoimine group (fig. 1A), and tannin molecules having nucleophilic reaction sites are specifically bound to the aminoimine group (fig. 1B), thereby increasing isoelectric point of the flocculant to obtain the plant tannin-based flocculant
In a preferred embodiment, the method comprises the following specific steps:
s1, heating the aqueous solution of the plant tannin in a water bath, continuously stirring the aqueous solution of the plant tannin, introducing nitrogen, and adjusting the pH value of the aqueous solution of the plant tannin to be alkaline after the temperature of the aqueous solution of the plant tannin reaches a first temperature interval to obtain a first solution;
s2, keeping the temperature of the first solution in a first temperature interval, keeping stirring and nitrogen introduction of the first solution continuously, dropwise adding a hexamethylenetetramine solution into the first solution under the condition, and after dropwise adding, continuously stirring and introducing nitrogen until the reaction is finished to obtain a second solution;
and S3, drying the second solution after the pH value of the second solution is acidic to obtain the environment-friendly plant tannin-based flocculant.
In a more preferable embodiment, the mass ratio of the plant tannin to the deionized water in the aqueous solution of the plant tannin is 1 (5-10).
In a more preferable embodiment, the first temperature range is 80 ℃ to 90 ℃, and the nitrogen flow is 3 mL/min to 5 mL/min.
In a more preferable embodiment, the pH value of the aqueous solution of the vegetable tannin is adjusted to 10-11 by using a sodium hydroxide solution.
In a more preferable embodiment, the concentration of the hexamethylenetetramine solution is 0.1mol/L, and the volume ratio of the plant tannin water solution to the hexamethylenetetramine solution is (2-10): 1.
In a more preferred embodiment, the dropping rate of the hexamethylenetetramine solution is 2-8 mL/min.
In a more preferable embodiment, the pH value of the second solution is adjusted to 2-3 by adopting 1mol/L hydrochloric acid solution, and then vacuum drying is carried out, wherein the drying temperature is 40-60 ℃.
In a more preferred embodiment, the step S3 further includes:
and adding ethanol or acetone into the second solution to perform dehydration and embrittlement to obtain a third solution, drying to obtain a solid, and crushing and grinding the solid to obtain the plant tannin-based flocculant.
It should be understood that ethanol and acetone are added for dehydration and embrittlement, which is a common technical means in the field, and the amount of ethanol and acetone can be added according to actual needs, and the final effect is not influenced by the amount; and after the ethanol and the acetone are added, the mixture can be placed for a period of time, or can be directly dried without being placed, so that the final effect is not influenced.
In a more preferred embodiment, the vegetable tannin is acacia negra tannin.
In another preferred embodiment, in the step S2, the reaction is performed for 1 to 4 hours to obtain the second solution.
In another exemplary embodiment of the invention, an environment-friendly plant tannin-based flocculant is provided, which is prepared by the preparation method of the environment-friendly plant tannin-based flocculant.
The isoelectric point of the obtained flocculant can be improved from about 2 of natural tannin to about 5, and the flocculation effect is good.
For better understanding, the present invention is further described below with reference to several specific examples, but the process is not limited thereto and the present disclosure is not limited thereto.
[ example 1 ]
Dissolving 10g of black wattle tannin in 50mL of deionized water at room temperature, and magnetically stirring for 20 minutes to obtain a black wattle tannin aqueous solution.
The aqueous solution of cercis negundo tannin was transferred to a three-necked flask, heated to 80 ℃ in a water bath, stirred and purged with nitrogen, and the pH was adjusted to 10 with a sodium hydroxide solution.
Slowly dripping 5mL of hexamethylenetetramine solution (0.1M) through a constant pressure dropping funnel at the dripping speed of 4mL/min, and after the dripping is finished, continuously stirring and introducing nitrogen for reaction for 3 hours.
After the reaction is finished, adjusting the pH value of the solution to 2 by adopting 1mol/L hydrochloric acid solution, drying the solution to constant weight in a vacuum drying oven at the temperature of 60 ℃, and crushing and grinding the solution to obtain the novel plant tannin-based flocculant.
The flocculant has a removal rate of 97.18% for 1g/L kaolin suspension at the addition of 120mg/L and a settling time of 1 h.
[ example 2 ] A method for producing a polycarbonate
Dissolving 10g of cercis negundo tannin in 100mL of deionized water at room temperature, and magnetically stirring for 20 minutes to obtain a cercis negundo tannin aqueous solution.
The aqueous solution of cercis negundo tannin was transferred to a three-necked flask, heated to 90 ℃ in a water bath, stirred and purged with nitrogen, and the pH was adjusted to 10.4 with sodium hydroxide solution.
Slowly dripping 10mL of hexamethylenetetramine solution (0.1M) through a constant pressure dropping funnel at the dripping speed of 8mL/min, and after the dripping is finished, continuously stirring and introducing nitrogen for reaction for 1 h.
And after the reaction is finished, adding ethanol or acetone into the product for dehydration and embrittlement, drying the product to constant weight in a vacuum drying oven at the temperature of 60 ℃, and crushing and grinding the product to obtain the novel plant tannin-based flocculant.
The flocculant has a removal rate of 99.22% for 1g/L kaolin suspension at a dosage of 125mg/L and a settling time of 1.5 h.
[ example 3 ]
Dissolving 10g of cercis negundo tannin in 50mL of deionized water at room temperature, and magnetically stirring for 20 minutes to obtain a cercis negundo tannin aqueous solution.
The aqueous solution of cercis negundo tannin was transferred to a three-necked flask, heated to 80 ℃ in a water bath, stirred and purged with nitrogen, and the pH was adjusted to 10.8 with sodium hydroxide solution.
Slowly dripping 15mL of hexamethylenetetramine solution (0.1M) through a constant pressure dropping funnel at the dripping speed of 6mL/min, and after the dripping is finished, continuously stirring and introducing nitrogen for reaction for 4 hours.
After the reaction is finished, adjusting the pH value of the solution to 2 by adopting 1mol/L hydrochloric acid solution, drying the solution to constant weight in a vacuum drying oven at the temperature of 40 ℃, and crushing and grinding the solution to obtain the novel plant tannin-based flocculant.
The flocculant has a removal rate of 97.04% for 1g/L kaolin suspension at a dosage of 25mg/L, and the sedimentation time is 1 h.
[ example 4 ]
Dissolving 10g of cercis negundo tannin in 100mL of deionized water at room temperature, and magnetically stirring for 20 minutes to obtain a cercis negundo tannin aqueous solution.
The aqueous solution of cercis negundo tannin was transferred to a three-necked flask, heated to 90 ℃ in a water bath, stirred and purged with nitrogen, and the pH was adjusted to 11 with a sodium hydroxide solution.
Slowly dripping 20mL of hexamethylenetetramine solution (0.1M) through a constant pressure dropping funnel at the dripping speed of 2mL/min, and after the dripping is finished, continuously stirring and introducing nitrogen for reaction for 4 hours.
After the reaction is finished, adjusting the pH value of the solution to 2 by adopting 1mol/L hydrochloric acid solution, drying the solution to constant weight in a vacuum drying oven at the temperature of 50 ℃, and crushing and grinding the solution to obtain the novel plant tannin-based flocculant.
The flocculant has a removal rate of 98% for 1g/L kaolin suspension at a dosage of 130mg/L, and the settling time is 1.5 h.
[ example 5 ]
Dissolving 10g of cercis negundo tannin in 50mL of deionized water at room temperature, and magnetically stirring for 20 minutes to obtain a cercis negundo tannin aqueous solution.
The aqueous solution of cercis negundo tannin was transferred to a three-necked flask, heated to 90 ℃ in a water bath, stirred and purged with nitrogen, and the pH was adjusted to 11 with a sodium hydroxide solution.
Slowly dripping 25mL of hexamethylenetetramine solution (0.1M) through a constant pressure dropping funnel at the dripping speed of 4mL/min, and after the dripping is finished, continuously stirring and introducing nitrogen for reaction for 3 hours.
And after the reaction is finished, adding ethanol or acetone into the product for dehydration and embrittlement, drying the product to constant weight in a vacuum drying oven at the temperature of 60 ℃, and crushing and grinding the product to obtain the novel plant tannin-based flocculant.
The flocculant has a removal rate of 79.35 percent for 1g/L kaolin suspension at the addition of 135mg/L and settling time of 1.5 h.
Potential testing
The flocculant obtained in example 1 was subjected to a potential test, and the result is shown in FIG. 2.
As can be seen from figure 2, the isoelectric point of the unmodified black wattle tannin is 2, the isoelectric point of the modified black wattle tannin is increased to about 5, and the isoelectric point of the flocculant is remarkably increased, so that the flocculant can be efficiently combined with negatively charged pollutants through the action of electrostatic attraction.
Infrared testing
The infrared test was carried out on the flocculant obtained in example 1, and the result is shown in FIG. 3.
From fig. 3, the characteristic peaks of acacia negra tannin can be seen: 3415cm -1 The broad peak at (a) is due to stretching vibration of-OH; appear at 1620 and 1507cm -1 The peak of (a) is characteristic of aromatic C ═ C bond elongation. These characteristic peaks also appear in the spectrum of cationic cercis negundo tannin, with slight variations in wavenumbers. The spectrum of cationic black wattle tannin is 3222 and 1402cm -1 Two new peaks, corresponding to the stretching of-NH-, appeared, indicating successful binding of the aminimide group to the acacia negra tannin.
By combining the tests, the flocculant obtained by the preparation method of the plant tannin-based flocculant provided by the invention has the advantages that the isoelectric point of the flocculant is effectively improved through reaction, so that the electrostatic binding capacity of the flocculant and negatively charged pollutants is improved, and the purposes of removing a large amount of pollutants such as suspended matters, rapidly purifying a water body and remarkably improving the water quality of the water body can be achieved. The kaolin removal rate is high under the conditions of low dosage and short settling time, and the highest kaolin removal rate can reach 99.22%.
The flocculant is simple in preparation process, easy to operate, free of formaldehyde in the whole preparation process, environment-friendly, low in cost and suitable for industrial production and application.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.
Claims (10)
1. The preparation method of the environment-friendly plant tannin-based flocculant is characterized in that plant tannin and hexamethylenetetramine are placed under alkaline conditions to react, at the moment, hexamethylenetetramine is decomposed to generate an intermediate aminoimine group, and tannin molecules with nucleophilic reaction sites are specifically combined with the aminoimine group, so that the isoelectric point of the flocculant is improved, and the plant tannin-based flocculant is obtained.
2. The method for preparing the environment-friendly plant tannin-based flocculant according to claim 1, characterized by comprising the following specific steps:
s1, heating the aqueous solution of the plant tannin in a water bath, continuously stirring the aqueous solution of the plant tannin, introducing nitrogen, and adjusting the pH value of the aqueous solution of the plant tannin to be alkaline after the temperature of the aqueous solution of the plant tannin reaches a first temperature interval to obtain a first solution;
s2, keeping the temperature of the first solution in a first temperature interval, keeping stirring and nitrogen introduction of the first solution continuously, dropwise adding a hexamethylenetetramine solution into the first solution under the condition, and after dropwise adding, continuously stirring and introducing nitrogen until the reaction is finished to obtain a second solution;
and S3, drying the second solution after the pH value of the second solution is acidic to obtain the environment-friendly plant tannin-based flocculant.
3. The preparation method of the environment-friendly plant tannin-based flocculant according to claim 2, wherein the mass ratio of the plant tannin to the deionized water in the aqueous solution of the plant tannin is 1 (5-10).
4. The preparation method of the environment-friendly plant tannin based flocculant according to claim 2, wherein the first temperature interval is 80-90 ℃ and the nitrogen flow is 3-5 mL/min.
5. The method for preparing the environment-friendly plant tannin-based flocculant according to claim 2, wherein a sodium hydroxide solution is adopted to adjust the pH value of an aqueous solution of the plant tannin to 10-11.
6. The preparation method of the environment-friendly plant tannin-based flocculant according to claim 2, wherein the concentration of the hexamethylenetetramine solution is 0.1mol/L, and the volume ratio of the plant tannin aqueous solution to the hexamethylenetetramine solution is (2-10): 1.
7. The preparation method of the environment-friendly plant tannin-based flocculant according to claim 2, wherein the dropping rate of the hexamethylenetetramine solution is 2-8 mL/min.
8. The method for preparing the environment-friendly plant tannin based flocculant according to claim 2, wherein the pH value of the second solution is adjusted to 2-3 by hydrochloric acid solution, and then vacuum drying is carried out at 40-60 ℃.
9. The method for preparing environment-friendly plant tannin-based flocculant according to any one of claims 1 to 8, wherein the plant tannin is black wattle tannin.
10. An environment-friendly plant tannin-based flocculant, which is characterized by being prepared by the preparation method of the environment-friendly plant tannin-based flocculant according to any one of claims 1 to 10.
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| JPH0566291A (en) * | 1991-07-09 | 1993-03-19 | Mitsubishi Nuclear Fuel Co Ltd | Manufacturing of metallic element absorbent, and absorption and separation of metallic element by use of the absorbent |
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| CN112441655A (en) * | 2020-11-06 | 2021-03-05 | 河海大学 | Cationic tannin flocculant for black wattle and preparation method thereof |
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|---|---|---|---|---|
| JPH0566291A (en) * | 1991-07-09 | 1993-03-19 | Mitsubishi Nuclear Fuel Co Ltd | Manufacturing of metallic element absorbent, and absorption and separation of metallic element by use of the absorbent |
| US5320664A (en) * | 1991-07-09 | 1994-06-14 | Mitsubishi Nuclear Fuel Company, Ltd. | Method of preparing metal element adsorbent and method of adsorbing and separating metal element using the same |
| US9956563B1 (en) * | 2017-10-21 | 2018-05-01 | Aicardo Roa-Espinosa | Separation of clean water from effluent streams |
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