CN107055729B - Dopamine-modified chitosan flocculant - Google Patents
Dopamine-modified chitosan flocculant Download PDFInfo
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- CN107055729B CN107055729B CN201710389155.2A CN201710389155A CN107055729B CN 107055729 B CN107055729 B CN 107055729B CN 201710389155 A CN201710389155 A CN 201710389155A CN 107055729 B CN107055729 B CN 107055729B
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- 229920001661 Chitosan Polymers 0.000 title claims abstract description 44
- 239000010865 sewage Substances 0.000 claims abstract description 56
- 229920002401 polyacrylamide Polymers 0.000 claims abstract description 43
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000011282 treatment Methods 0.000 claims abstract description 26
- 229960003638 dopamine Drugs 0.000 claims abstract description 15
- 238000004043 dyeing Methods 0.000 claims abstract description 10
- 239000002244 precipitate Substances 0.000 claims abstract description 10
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000001179 sorption measurement Methods 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 238000003756 stirring Methods 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 19
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical compound [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 claims description 15
- 238000000502 dialysis Methods 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 14
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 12
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 10
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 10
- 239000000047 product Substances 0.000 claims description 10
- 239000002351 wastewater Substances 0.000 claims description 8
- INQOMBQAUSQDDS-UHFFFAOYSA-N iodomethane Chemical compound IC INQOMBQAUSQDDS-UHFFFAOYSA-N 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 5
- 239000012279 sodium borohydride Substances 0.000 claims description 5
- 235000009518 sodium iodide Nutrition 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 2
- 238000005189 flocculation Methods 0.000 abstract description 39
- 230000016615 flocculation Effects 0.000 abstract description 39
- 229920000642 polymer Polymers 0.000 abstract description 23
- 230000000694 effects Effects 0.000 abstract description 13
- 230000002378 acidificating effect Effects 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 2
- 238000004064 recycling Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 35
- 239000008394 flocculating agent Substances 0.000 description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 229960001506 brilliant green Drugs 0.000 description 8
- HXCILVUBKWANLN-UHFFFAOYSA-N brilliant green cation Chemical compound C1=CC(N(CC)CC)=CC=C1C(C=1C=CC=CC=1)=C1C=CC(=[N+](CC)CC)C=C1 HXCILVUBKWANLN-UHFFFAOYSA-N 0.000 description 8
- ZXJXZNDDNMQXFV-UHFFFAOYSA-M crystal violet Chemical compound [Cl-].C1=CC(N(C)C)=CC=C1[C+](C=1C=CC(=CC=1)N(C)C)C1=CC=C(N(C)C)C=C1 ZXJXZNDDNMQXFV-UHFFFAOYSA-M 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 7
- 239000006228 supernatant Substances 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 238000002835 absorbance Methods 0.000 description 4
- 230000003311 flocculating effect Effects 0.000 description 4
- 239000001046 green dye Substances 0.000 description 4
- 238000005119 centrifugation Methods 0.000 description 3
- 230000006196 deacetylation Effects 0.000 description 3
- 238000003381 deacetylation reaction Methods 0.000 description 3
- 239000000975 dye Substances 0.000 description 3
- 238000009775 high-speed stirring Methods 0.000 description 3
- 230000000813 microbial effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 238000010297 mechanical methods and process Methods 0.000 description 2
- 239000003129 oil well Substances 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 241000237536 Mytilus edulis Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000013067 intermediate product Substances 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
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 235000020638 mussel Nutrition 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
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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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
- C08B37/0027—2-Acetamido-2-deoxy-beta-glucans; Derivatives thereof
- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/30—Nature of the water, waste water, sewage or sludge to be treated from the textile industry
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Biochemistry (AREA)
- Materials Engineering (AREA)
- Molecular Biology (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- General Health & Medical Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
The invention provides a chitosan flocculant for treating sewage containing polyacrylamide, which is prepared by grafting dopamine with an o-dihydroxy structure on chitosan through glutaraldehyde under an acidic condition. The flocculant is green and pollution-free in used materials and has small harm to the environment; the novel flocculant synthesized by the dopamine grafted chitosan greatly improves the adsorption capacity and solubility of the chitosan, and has good flocculation effect on polymer-containing sewage; the precipitate after the flocculant treatment of the polyacrylamide-containing sewage can be used for secondary flocculation of dye sewage, and has a relatively ideal flocculation effect; the flocculant realizes the secondary recycling of polyacrylamide, has better flocculation effect on polymer-containing sewage and printing and dyeing sewage, greatly improves the flocculation efficiency and saves the flocculation cost.
Description
Technical Field
The invention belongs to the technical field of sewage treatment, and particularly relates to a preparation method of a novel modified chitosan flocculant and a treatment process for petroleum sewage and printing and dyeing sewage by using the flocculant.
Background
At present, Polyacrylamide (PAM) is widely used for oil displacement in most oil fields in China, but PAM in oil well produced liquid enables oil field sewage to become a complex oil-water system. Compared with the common sewage, the polymer-containing sewage comprises the following components: the viscosity is higher, the emulsion system is more stable, the interfacial film strength is increased, the demulsification difficulty is increased, and the sand carrying amount and the oil carrying amount of sewage are increased. Thus increasing the difficulty of sewage treatment due to the existence of PAM. Most oil fields in China only have some simple treatments, and the treatments are often difficult to reach the national emission standard. If the sewage which does not reach the standard is discharged into the ground, the formation pores are blocked, and the water injection capacity and the oil well yield are reduced; if discharged to the ground, will cause serious harm to the health and ecological environment of human beings and animals. Therefore, the treatment of polymer-containing sewage is an important content of the treatment of oilfield sewage.
The prior method for treating polymer-containing sewage mainly comprises a physical mechanical method, a microbial treatment method and a chemical treatment method. The physical mechanical method has simple treatment process, but needs large-scale treatment equipment and has low treatment efficiency. The microbial treatment method has the advantages of high treatment efficiency, cleanness and no pollution, but the research technology is immature, the microbial source is single, the environmental adaptability is poor, and the requirement of large-scale treatment of polymer-containing sewage is difficult to achieve. The chemical treatment method mainly comprises inorganic flocculating agents, such as polymeric ferric sulfate and polymeric aluminum chloride, and has the advantages of simple treatment method and economy; the biggest disadvantage is that secondary pollution is often caused. However, no research on the treatment of polymer-containing sewage by organic flocculant has been reported at present.
In view of the above, the current methods for treating polymer-containing wastewater have many disadvantages and needs to be improved. The invention provides a novel dopamine-modified chitosan organic flocculant, which belongs to a new technical field. The chitosan is a flocculant, is green and environment-friendly, has low price and can be biodegraded; dopamine is found in adhesion protein biologically secreted from marine mussel, and has good biocompatibility, adhesion and water absorption. The dopamine is introduced to the chitosan skeleton, so that the adsorbability of chitosan is improved, and PAM flocculation treatment is realized; and the settling compound of PAM and flocculant can be recovered for secondary utilization to treat the printing and dyeing sewage.
Disclosure of Invention
In order to solve the problems, the invention provides a chitosan flocculant for treating polymer-containing sewage, a preparation method thereof and a corresponding sewage treatment process, thereby solving the problem of efficient and green sewage treatment.
The chitosan flocculant provided by the invention has the following structural formula:
where n ranges from 1500-.
The chitosan flocculant provided by the invention is prepared by grafting dopamine with an o-dihydroxy structure on chitosan through glutaraldehyde under an acidic condition.
The flocculant, one of which is prepared by the following method
1) Dissolving chitosan in acid solution, adding glutaraldehyde, and stirring at 30-50 deg.C for reaction; putting the solution after reaction into a dialysis bag with the molecular weight cutoff of 14000 for dialysis;
2) adding excessive dopamine into the dialysate obtained in the step 1), and stirring and reacting at 20-30 ℃; putting the solution after reaction into a dialysis bag with the cut-off molecular weight of 14000 for dialysis;
3) adding sodium borohydride into the dialysate obtained in the step 2), and stirring and reacting at 20-30 ℃; centrifuging the reaction solution to obtain a precipitate, and drying the precipitate;
4) dissolving 5 parts by weight of methyl iodide, 2 parts by weight of sodium hydroxide and 3.6 parts by weight of sodium iodide in 120 parts by weight of N-methyl-2-pyrrolidone respectively, and uniformly stirring;
5) adding the precipitate obtained in the step 3) into the solution in the step 4, and stirring and reacting at the temperature of 30-60 ℃; and after the reaction is finished, adding acetone to precipitate a product, filtering or centrifuging the solution to obtain a product, and drying to obtain the flocculant.
Preferably, the acid solution in step 1) is hydrochloric acid or acetic acid.
The mass ratio of the dopamine to the chitosan in the step 2) is 1:1-5: 1. The mass ratio of the methyl iodide to the chitosan in the step 4) is 1:1-3: 1.
The flocculant provided by the invention is used for treating sewage containing polyacrylamide and printing and dyeing sewage.
One application method is that after the sewage containing polyacrylamide is treated, the compound of flocculant and polyacrylamide is recovered and then used for treating the printing and dyeing sewage.
The flocculant is green and pollution-free in used materials, good in biocompatibility and low in price; the novel flocculant effectively synthesized by the dopamine grafted chitosan greatly improves the adsorption capacity and the solubility of the chitosan, has obvious flocculation effect on polymer-containing sewage, and fills the gap of the organic flocculant for treating the polymer-containing sewage. PAM is also a flocculant and is commonly used for sewage treatment; therefore, the dye sewage can be secondarily flocculated by treating the precipitation compound containing the polymer sewage by using the flocculating agent, so that secondary recycling of the flocculating agent and PAM is realized, the flocculation efficiency is greatly improved, and the flocculation cost is saved.
Drawings
FIG. 1: preparation route of the flocculant of the invention; wherein (i) Chi is chitosan raw material, (ii) GDC is intermediate product generated by grafting glutaraldehyde and chitosan, and (iii) GDC-g-DA is final product generated by grafting GDC and dopamine.
FIG. 2 is a graph showing the effect of flocculating the methyl violet dye wastewater with the flocculant III and the PAM.
FIG. 3 is a comparison graph of flocculating agent III and PAM flocculating brilliant green dye sewage before and after flocculation.
FIG. 4: the flocculant III of the invention has a relationship graph of PAM removal rate and PH.
FIG. 5: the relationship graph of the mass of the flocculant III and the PAM removal rate is shown.
Detailed Description
The present invention will be described in detail with reference to specific examples.
Example 1:
(1) 1 g of chitosan (degree of deacetylation: 80%, relative molecular mass: 35 ten thousand) was dissolved in 50ml of acetic acid (0.1mol/L) solution, adjusted to pH 5 with 0.1mol/L sodium hydroxide solution, 120 g of glutaraldehyde was added, and the reaction was stirred at high speed at 48 ℃ for 24 hours. The reacted solution was filled into a dialysis bag with a molecular weight cut-off of 14000 and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(2) And (3) adding 1 g of dopamine into the dialysate in the step (1), and reacting for 12 hours at a high speed and at a temperature of 25 ℃. The solution after reaction was filled into a cut-off 14000 dialysis bag and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(3) And (3) adding 0.5 g of sodium borohydride into the dialysate in the step (2), and stirring at 25 ℃ for 12 hours. The solution was centrifuged at 2000rpm and the lower precipitate was dried at 100 ℃ for 12 h.
(4) 5 g of methyl iodide, sodium hydroxide and 1 g of sodium iodide were dissolved in 120 g of N-methyl-2-pyrrolidone, respectively.
(5) Adding the substance in the step (3) into the solution in the step (4), and reacting for 12h at 50 ℃ by high-speed stirring. After the reaction is finished, 100 g of acetone is added to precipitate the product, the product is obtained by centrifugation at 2000rpm and is dried for 24 hours at 100 ℃, and the flocculant I with the grafting rate of 52 percent is obtained.
Example 2:
(1) 1 g of chitosan (degree of deacetylation: 80%, relative molecular mass: 35 ten thousand) was dissolved in 50ml of acetic acid (0.1mol/L) solution, adjusted to pH 5 with 0.1mol/L sodium hydroxide solution, 120 g of glutaraldehyde was added, and the reaction was stirred at high speed at 48 ℃ for 24 hours. The reacted solution was filled into a dialysis bag with a molecular weight cut-off of 14000 and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(2) And (3) adding 3 g of dopamine into the dialysate in the step (1), and reacting for 12 hours at a high speed and at a temperature of 25 ℃. The solution after reaction was filled into a cut-off 14000 dialysis bag and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(3) And (3) adding 0.5 g of sodium borohydride into the dialysate in the step (2), and stirring at 25 ℃ for 12 hours. The solution was centrifuged at 2000rpm and the lower precipitate was dried at 100 ℃ for 12 h.
(4) 5 g of methyl iodide, sodium hydroxide and 3 g of sodium iodide were dissolved in 120 g of N-methyl-2-pyrrolidone, respectively.
(5) Adding the substance in the step (3) into the solution in the step (4), and reacting for 12h at 50 ℃ by high-speed stirring. After the reaction is finished, 100 g of acetone is added to precipitate the product, the product is obtained by centrifugation at 2000rpm and is dried for 24h at 100 ℃, and the flocculant II with the grafting rate of 60% is obtained.
Example 3:
(1) 1 g of chitosan (degree of deacetylation 90%, relative molecular mass 25 ten thousand) was dissolved in 50ml of hydrochloric acid (0.1mol/L) solution, adjusted to pH 5 with 0.1% by mass sodium hydroxide solution, 120 g of glutaraldehyde was added, and the reaction was stirred at high speed at 48 ℃ for 24 hours. The reacted solution was filled into a dialysis bag with a molecular weight cut-off of 14000 and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(2) And (3) adding 5 g of dopamine into the dialysate in the step (1), and reacting for 12 hours at a high speed and at a temperature of 25 ℃. The solution after reaction was filled into a cut-off 14000 dialysis bag and the bag was dialyzed in 1L of water for 12 hours, which was repeated 7 times.
(3) And (3) adding 0.5 g of sodium borohydride into the dialysate in the step (2), and stirring at 25 ℃ for 12 hours. The solution was centrifuged at 2000rpm and the lower precipitate was dried at 100 ℃ for 12 h.
(4) Separately, 5 g of methyl iodide, sodium hydroxide and 1 g of sodium iodide were added to 120 g of N-methyl-2-pyrrolidone.
(5) Adding the substance in the step (3) into the solution in the step (4), and reacting for 12h at 50 ℃ by high-speed stirring. After the reaction is finished, 100 g of acetone is added to precipitate the product, the product is obtained by centrifugation at 2000rpm and is dried for 24h at 100 ℃, and the flocculating agent III with the grafting rate of 75% is obtained.
Example 4 treatment of Polymer-containing wastewater and Secondary flocculation of methyl Violet dye wastewater
Respectively preparing polymer-containing sewage with PAM concentration of 500mg/L and PH of 7 and printing and dyeing sewage with methyl violet concentration of 100 mg/L. 5 parts of 20ml polymer-containing sewage are taken, chitosan, polyaluminium chloride, a flocculating agent I, a flocculating agent II, a flocculating agent III and 20mg of the flocculating agent III with the same mass are respectively added, the mixture is rapidly stirred at 200rpm for 5min, then slowly stirred at 50rpm for 15min, the mixture is kept still for 2 hours until precipitation is generated, supernatant of the solution before and after flocculation is taken to detect the viscosity of the solution, and the removal rate of PAM is calculated according to a formula Q ═ (No-Ne)/No × 100% (wherein Q represents the removal rate, No and Ne respectively represent the viscosity of the solution before and after flocculation, and the unit is Pa.S). And (3) performing secondary flocculation, namely adding 20mL of printing and dyeing sewage of 5 parts by weight and 20mL of the flocculation precipitation compound with the same volume respectively, rapidly stirring at 200rpm for 5min, slowly stirring at 50rpm for 15min, and standing for 2 hours. The supernatant was taken to determine the uv absorbance of methyl violet and the clearance was calculated according to the formula Q ═ Ao-Ae)/Ao × 100% (where Q represents the clearance and Ao and Ae represent the uv absorbance of the solution before and after flocculation, respectively, in units of L/(g · cm)).
TABLE 1 Effect of different flocculants on PAM and methyl violet removal
| Flocculating agent | Removal rate of polyacrylamide | Methyl violet |
| Chitosan | ||
| 25％ | 20％ | |
| Polyaluminium chloride | 43％ | 58％ |
| Flocculating agent I | 53％ | 71％ |
| Flocculant II | 57％ | 76％ |
| Flocculating agent III | 62％ | 81％ |
The viscosity of the sewage is determined by PAM which is a main pollutant in the polymer-containing sewage; therefore, when the polymer-containing sewage is treated, the viscosity is an important factor for evaluating the flocculation effect of the sewage. We therefore calculated the PAM removal by the viscosity of the wastewater before and after flocculation. As can be seen from Table 1, the removal rate of polyacrylamide by the dopamine-modified chitosan is far higher than that of polyaluminium and unmodified chitosan; therefore, the fact that the adhesion and bridging capacity of the chitosan are improved by the dopamine is also verified. From table 1 and fig. 2, it can be seen that the secondary flocculation of methyl violet sewage also achieves a better flocculation effect, realizes the reuse of the flocculant and PAM, greatly improves the flocculation efficiency, and saves the flocculation cost.
Example 5 treatment of Polymer-containing wastewater and Secondary flocculation Bright Green dye wastewater
Respectively preparing polymer-containing sewage with PAM concentration of 500mg/L and PH of 9 and printing and dyeing sewage with brilliant green concentration of 150 mg/L. 5 parts of 20ml polymer-containing sewage are taken, chitosan, polyaluminium chloride, a flocculating agent I, a flocculating agent II, a flocculating agent III and 20mg of the flocculating agent I, the flocculating agent III and the flocculating agent III with the same mass are respectively added, the mixture is rapidly stirred for 5min at 200rpm, then slowly stirred for 15min at 50rpm, and kept still for 2 hours until precipitation is generated, and the removal rate of PAM is calculated according to a formula Q ═ (No-Ne)/No 100% (wherein Q represents the clearance rate, No and Ne respectively represent the viscosity of the solution before and after flocculation, and the unit is Pa.S). And (3) performing secondary flocculation, namely adding 20mL of printing and dyeing sewage of 5 parts by weight and 20mL of the flocculation precipitation compound with the same volume respectively, rapidly stirring at 200rpm for 5min, slowly stirring at 50rpm for 15min, and standing for 2 hours. The supernatant was taken to determine the ultraviolet absorbance of brilliant green according to the formula Q ═ Ao-Ae)/Ao × 100% (wherein Q represents the clearance, Ao and Ae represent the ultraviolet absorbance of the solution before and after flocculation, respectively, and the unit is L/(g · cm)) to calculate the brilliant green clearance.
TABLE 2 flocculant removal effect on PAM and Bright Green
| Flocculating agent | PAM removal rate | Removal rate of brilliant |
| Chitosan | ||
| 25％ | 16％ | |
| Polyaluminium chloride | 43％ | 67％ |
| Flocculating agent I | 58％ | 85％ |
| Flocculant II | 61％ | 90％ |
| Flocculating agent III | 67％ | 94％ |
As can be seen from Table 2, the flocculation effect of the synthesized novel chitosan flocculant is far better than that of the traditional flocculant, wherein the flocculation effect of the flocculant C is the best. The result of primary flocculation of PAM in comparative example 4 can be found that PAM is flocculated better under alkaline conditions. The secondary flocculation of the brilliant green dye sewage can be seen from figure 3 that the brilliant green color before and after flocculation is obviously changed, the brilliant green dye sewage after flocculation is nearly colorless, and the removal rate reaches 94%.
Example 6 Effect of pH on flocculating PAM
Respectively preparing polymer-containing sewage with PAM concentration of 500mg/L and PH of 3, 5, 7, 9, 11 and 13, respectively taking 20ml, adding flocculating agent III20mg with the same mass, quickly stirring at 200rpm for 5min, then slowly stirring at 50rpm for 15min, standing for 2 hours until precipitation is generated, taking supernatant of the solution before and after flocculation, detecting the viscosity of the supernatant, and calculating the PAM clearance according to a formula Q ═ (No-Ne)/No × 100% (wherein Q represents clearance, No and Ne respectively represent the viscosity of the solution before and after flocculation, and the unit is Pa.S). The PAM clearance was plotted against PH, and as shown in fig. 4, the PAM clearance increased gradually with increasing PH, providing better flocculation in alkaline than acidic environments, with the highest removal at PH 11.
Example 7 Effect of different flocculant addition levels on flocculating PAM
Preparing polymer-containing sewage with the concentration of PAM of 500mg/L and the PH of 11. Taking 20mL of 6 parts of polymer-containing sewage with the same volume, respectively adding 5mg of flocculant III, 10mg of flocculant, 15mg of flocculant, 20mg of flocculant, 25mg of flocculant, 30mg of flocculant, 35mg, rapidly stirring at 200rpm for 5min, slowly stirring at 50rpm for 15min, standing for 2 hours until precipitation is generated, taking supernatant of the solution before and after flocculation, detecting the viscosity of the supernatant, and calculating the removal rate of PAM according to a formula Q ═ (No-Ne)/No 100% (wherein Q represents the removal rate, and No and Ne respectively represent the viscosity of the solution before and after flocculation, and the unit is Pa.S). And (3) drawing a relation graph of the PAM clearance and the mass of the flocculant III, wherein the removal rate is increased and then tends to be stable along with the increase of the addition amount of the flocculant from FIG. 5, and the removal rate reaches the maximum when 25mg is added, and basically keeps stable afterwards. The technical means disclosed by the scheme of the invention are not limited to the technical means disclosed by the technical means, and the technical scheme also comprises the technical scheme formed by any combination of the technical characteristics. While the foregoing is directed to embodiments of the present invention, it will be appreciated by those skilled in the art that various changes may be made in the embodiments without departing from the principles of the invention, and that such changes and modifications are intended to be included within the scope of the invention.
Claims (7)
1. A chitosan flocculant has a structural formula as follows:
wherein n is 1500-;
the preparation method of the chitosan flocculant comprises the following steps:
1) adding glutaraldehyde into chitosan solution, and stirring at 30-50 deg.C for reaction; putting the solution after reaction into a dialysis bag with the molecular weight cutoff of 14000 for dialysis;
2) adding excessive dopamine into the dialysate obtained in the step 1), and stirring and reacting at 20-30 ℃; putting the solution after reaction into a dialysis bag with the cut-off molecular weight of 14000 for dialysis;
3) adding sodium borohydride into the dialysate obtained in the step 2), and stirring and reacting at 20-30 ℃; centrifuging the reaction solution to obtain a precipitate, and drying the precipitate;
4) separately, 5 parts by weight of methyl iodide, 2 parts by weight of sodium hydroxide and 3.6 parts by weight of sodium iodide were added to 120 parts by weight of N-methyl-2-pyrrolidone to prepare a solution;
5) adding the precipitate obtained in the step 3) into the solution obtained in the step 4), and stirring and reacting at the temperature of 30-60 ℃; and after the reaction is finished, adding acetone to precipitate a product, filtering or centrifuging the solution to obtain a product, and drying to obtain the flocculant.
2. The chitosan flocculant of claim 1, wherein the acid solution in step 1) is hydrochloric acid or acetic acid.
3. The chitosan flocculant of claim 1, wherein the mass ratio of dopamine to chitosan in step 2) is 1-5: 1.
4. The chitosan flocculant of claim 1, wherein the mass ratio of methyl iodide to chitosan in step 4) is 1-3: 1.
5. Use of the chitosan flocculant of claim 1 in the treatment of sewage containing polyacrylamide.
6. Use of the chitosan flocculant of claim 1 for treating printing wastewater.
7. A method for treating sewage, which is characterized in that the method comprises the steps of adding the chitosan flocculant of claim 1 into sewage containing polyacrylamide, adsorbing, recovering the flocculant, and adding the flocculant into printing and dyeing sewage for adsorption.
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| CN109337944A (en) * | 2018-10-30 | 2019-02-15 | 浙江海洋大学 | A method of flocculant is prepared using bacillus marinus |
| CN109402193A (en) * | 2018-11-08 | 2019-03-01 | 浙江海洋大学 | A method of flocculant is prepared using ocean cock Salmonella |
| CN110327896A (en) * | 2019-06-21 | 2019-10-15 | 中科广化（重庆）新材料研究院有限公司 | A kind of magnetism poly-dopamine/carboxymethyl chitosan adsorbent and the preparation method and application thereof |
| CN114622411B (en) * | 2019-12-20 | 2023-10-20 | 晋江亿兴隆纺织实业有限公司 | Environment-friendly sizing process of all-cotton yarn |
| CN112520934B (en) * | 2020-12-18 | 2022-09-20 | 华自科技股份有限公司 | Method for producing tap water by utilizing magnetic weighting agent coagulation magnetic separation technology |
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| KR20100061987A (en) * | 2008-12-01 | 2010-06-10 | 한밭대학교 산학협력단 | The coagulation composition which contains chitosan and sulfate compounds for water treatment and a method of preparing thereof |
| CN101775083A (en) * | 2010-02-24 | 2010-07-14 | 安徽师范大学 | Preparation method, using method for modified chitosan and application thereof |
| CN102079795A (en) * | 2009-11-27 | 2011-06-01 | 中国人民解放军第二炮兵总医院 | Preparation of water-soluble crosslinked chitosan and application thereof |
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| KR20100061987A (en) * | 2008-12-01 | 2010-06-10 | 한밭대학교 산학협력단 | The coagulation composition which contains chitosan and sulfate compounds for water treatment and a method of preparing thereof |
| CN102079795A (en) * | 2009-11-27 | 2011-06-01 | 中国人民解放军第二炮兵总医院 | Preparation of water-soluble crosslinked chitosan and application thereof |
| CN101775083A (en) * | 2010-02-24 | 2010-07-14 | 安徽师范大学 | Preparation method, using method for modified chitosan and application thereof |
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