CN110078355B - Flocculating agent applied to sludge conditioning and synthesis method thereof - Google Patents

Flocculating agent applied to sludge conditioning and synthesis method thereof Download PDF

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CN110078355B
CN110078355B CN201910466617.5A CN201910466617A CN110078355B CN 110078355 B CN110078355 B CN 110078355B CN 201910466617 A CN201910466617 A CN 201910466617A CN 110078355 B CN110078355 B CN 110078355B
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曾波
李山
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Hubei Huayao Biotechnology Co ltd
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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
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
    • C02F11/147—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using organic substances

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Abstract

The invention discloses a flocculating agent applied to sludge conditioning and a synthesis method thereof. The flocculant is a polymer represented by a general formula (1); synthesizing a macromolecular initiator by lignin, 2-bromoisobutyryl bromide and an organic ion solution in an ice water bath at 4 ℃; under the protection of ice water bath and nitrogen at 4 ℃, under the catalysis of copper bromide and reaction ligand, the macromolecular initiator and the reaction monomer are polymerized to obtain the final flocculant. The novel lignin anion flocculant obtained by the invention has a strong adsorption function and can be widely applied to flocculation of inorganic colloid and heavy metal cations in sludge; the molecular structure of the prepared and synthesized material is controllable, the reaction condition is mild, the environment is friendly, and the method is suitable for mass application.

Description

Flocculating agent applied to sludge conditioning and synthesis method thereof
Technical Field
The invention belongs to the technical field of sludge treatment, and particularly relates to a flocculant applied to sludge conditioning and a synthesis method thereof.
Background
Sludge is generally a byproduct after urban sewage treatment, still contains a large amount of moisture, contains a large amount of germs, parasites, organic toxic substances, inorganic heavy metals, silt and the like in solid contents, is often accompanied by odor, and often causes secondary pollution if the sludge is randomly stacked or improperly treated. The water content in the sludge is more than 90%, and the solid floc structure in the sludge is conveyed, so that the problems of high transportation cost, large occupied area and the like are caused, and the ideal effect cannot be achieved by directly performing general dehydration treatment. Common sludge dewatering treatment modes include sludge concentration, sludge dewatering, sludge temperature and sludge conditioning. Sludge concentration often has the problems of large power consumption, low concentration ratio and the like. The sludge after natural drying and mechanical dehydration treatment has the defects of long dehydration time, high maintenance cost and high power consumption of mechanical dehydration. Sludge stabilization is generally performed by anaerobic digestion treatment, and can generate usable biogas, but the investment cost is high, the biogas production time is long, the operation and management cost is high, and the sludge stabilization is easily influenced by the environment.
The reduction and resource recycling of the sludge through sludge treatment are better solutions for reasonable sludge treatment. The sludge contains a large amount of microorganism EPS, organic nutrients and various trace elements, the sludge after dehydration and reduction treatment can be used as vegetation soil after composting fermentation, and humic acid and the like in the sludge can be directly used as fertilizers after further processing and extraction. However, the compost also contains a large amount of inorganic heavy metals and toxins, and the compost is directly composted without treatment, so that heavy metal plants are often accumulated and finally enter a human body through a food chain, and therefore, the compost needs to be subjected to harmless and temperature treatment. In addition, the dewatered sludge is directly subjected to compost fermentation, the nutrient utilization is not high, and a large amount of organic nutrients are lost after dewatering.
Sludge conditioning is often required for the purpose of reducing and detoxifying sludge. Common sludge conditioning methods include chemical conditioning, material conditioning, and microbial conditioning. The physical conditioning comprises ultrasonic conditioning and microwave conditioning, wherein the ultrasonic conditioning can disintegrate sludge extracellular polymers, disperse sludge particles and increase the specific surface area, but causes the sludge dewatering performance to be deteriorated; the microwave conditioning has the advantages of high heating speed, easy operation and control and energy saving, but the depth of penetrating the sludge is limited, and the conditioning effect is not ideal. The microbial conditioning is to improve the dehydration performance of the sludge by using microbial cells as a flocculating agent, but the treatment period is long and the treatment effect is not obvious.
The common chemical conditioning is to condition the sludge by using inorganic matters, organic polymers or natural modified organic polymers as flocculating agents. The inorganic conditioner is often used in a large amount, so that the volume of the dewatered sludge is large, and the requirements on pH and ionic strength are high. The organic polymer conditioner gradually replaces the inorganic conditioner, the dosage of the organic polymer conditioner is small, the influence of pH and ionic strength is small, the sludge amount after conditioning is small, but the synthesis process is complex, the process requirement is high and difficult to control, and the cost is high. Most of natural modified polymeric flocculants are modified and graft copolymerized by starch, cellulose, chitin, lignin and the like, and the natural modified polymeric flocculants are cheap in synthetic raw materials and efficient in conditioning effect. However, the common natural modified polymer organic matters are generally subjected to Mannich graft copolymerization or potassium permanganate serving as an initiator, the reaction regulation is harsh, and the yield is not high. ATRP is an atom transfer radical polymerization method developed by Matyjaszewski of the university of Calycor-Meilong, which is widely applied to lignin modification and grafting, and has the advantages of mild reaction conditions, controllable synthetic polymer molecules and the like, but the atom transfer radical polymerization method is not reported when being applied to lignin modification grafting reaction of sludge flocculant.
Disclosure of Invention
In order to solve the problems, the embodiment of the invention provides a flocculant applied to sludge conditioning and a synthesis method thereof.
The technical scheme is as follows:
a flocculant applied to sludge conditioning is a compound represented by a general formula (1).
Figure DEST_PATH_IMAGE001
Specifically, "Lignin" in the general formula (1) represents a polyguaiacyl, polyviola-tyl or polyphenylyl group structure in the molecular structure of Lignin, and "Lignin" in the general formula (1)m，n，p，qEach represents a square bracket [ 2 ] in the respective general formula (1)]"the number of repeating units;m，n，p，qare all positive integers greater than or equal to 1.
Further, R in the general formula (1)1Independently selected from the general formula (2)
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General formula (3)
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General formula (4)
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General formula (5)
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General formula (6)
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General formula (7)
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One or more of them.
Further, R in the general formula (2)2R in the general formula (3)3R in the general formula (4)3R in the general formula (5)5R in the general formula (6)6R in the general formula (7)7Each independently selected from alkyl groups having 1 to 6 carbon atoms or phenylalkyl groups having 7 to 10 carbon atoms.
A method for synthesizing a flocculant applied to sludge conditioning comprises the following steps:
preparing a macromolecular initiator: dissolving 10-15 parts of lignin in 200-500 parts of organic ionic liquid, heating at 95-105 ℃ for 4.5-6 h, adding 70-80 parts of 2-bromoisobutyryl bromide in an ice-water bath at 4 ℃ after the lignin is safely dissolved, and reacting for 24h to form reaction liquid; adding the reaction solution into 500-1000 parts of water at the speed of 0.01-0.1 part/min to obtain a precipitate, washing and filtering the precipitate with 500-1000 parts of diethyl ether for 3-5 times, and then carrying out vacuum freeze drying to obtain a macromolecular initiator;
synthesis of lignin-based flocculant: adding accurately weighed 1-1.5 parts of the macroinitiator prepared in the step (1) into 200-500 parts of organic ionic liquid to form an ionic solution reaction system; then, respectively adding 0.01-0.02 part of copper bromide and 0.5-1.5 parts of reaction ligand into an ionic solution reaction system at 4 ℃ under the protection of ice water bath and nitrogen; adding a mixed solution of a reaction monomer and methanol in a mass ratio of 1: 2-1: 5 into the ionic solution reaction system at a speed of 0.01-0.1 part/min, and reacting for 4 hours at 15-30 ℃; then washing and filtering the mixture for 3-5 times by using 500-1000 parts of distilled water to obtain a reaction product; placing the reaction product in an acetone solvent, and extracting for 24 hours at 120 ℃ to obtain a white colloidal polymer; washing the white colloidal polymer with 500-1000 parts of distilled water, carrying out suction filtration for 3-5 times, and carrying out vacuum freeze drying to obtain the flocculant.
Specifically, the lignin in the step (i) is one of high-boiling alcohol lignin, acetic acid lignin or cellulose enzymolysis lignin.
Specifically, the organic ionic liquid in the step (i) is one or more of fluorinated heterocyclic nitrogen compounds.
Specifically, 24-60 parts of one or more of pyrrole, imidazole, pyridine, pyridazine or pyrazine can be added to the reactant in the step (i).
Specifically, the reaction ligand in the step (c) is one of pentamethyldiethylenetriamine, 1,4,7,10, 10-hexamethyltriethylenetetramine, N1- (2- (dimethylamino) ethyl) -N2 ((dimethylamino) methyl) -N1, N2 dimethylethane-1, 2-diamine, N- (ethane-1, 2-diyl) bis (N, N '-trimethylformamide), and N, N-methylenebis (N, N' -trimethylformamide).
Specifically, the reactive monomer in step (II) may be represented by the general formula (8)
Figure 354119DEST_PATH_IMAGE008
And (4) showing.
The technical scheme adopted by the invention at least has the following beneficial effects: the invention adopts an ATRP graft copolymerization method to prepare the graft copolymer
Monomers capable of generating anions in the water phase are polymerized onto lignin molecules to obtain the novel lignin anion flocculant which has a strong adsorption function and can be widely applied to flocculation of inorganic colloid and heavy metal cations in sludge. The preparation method of the flocculant synthesized by the invention has the advantages of high product purity, controllable polymerization degree structure of synthesized high polymer, mild reaction condition, environmental protection and suitability for mass application.
Drawings
FIG. 1 is a general structural diagram of a flocculant applied to sludge conditioning according to an embodiment of the present invention;
FIG. 2 shows a lignin prepared according to an embodiment of the present invention1H-NMR spectrum;
FIG. 3 shows a wood product according to an embodiment of the present inventionOf lignin macroinitiators1H-NMR spectrum;
FIG. 4 shows a lignin graft polymer1H-NMR spectrum;
FIG. 5 is an ATR-FTIR spectrum of a lignin, a lignin macroinitiator, a lignin graft polymer, provided by embodiments of the present invention;
FIG. 6 is a TGA thermal stability graph of a lignin and a lignin graft polymer provided by embodiments of the present invention;
FIG. 7 is a specific resistance diagram of sludge after the lignin graft polymer is applied to sludge flocculation according to an embodiment of the present invention;
FIG. 8 is a graph of water content of mud cake after the lignin graft polymer is applied to sludge flocculation according to an embodiment of the present invention;
FIG. 9 is a graph of the turbidity of the filtrate after the lignin graft polymer is applied to sludge flocculation according to an embodiment of the present invention;
FIG. 10 is a graph of total TOC of a lignin-grafted polymer after sludge flocculation, according to an embodiment of the present invention;
FIG. 11 is a molecular diagram of an organic HPSEC in raw sludge after extraction by a method according to an embodiment of the present invention;
FIG. 12 is a molecular diagram of an organic HPSEC after raw sludge conditioning by L-g-P10 extracted by a method according to an embodiment of the present invention;
FIG. 13 is a molecular diagram of an organic HPSEC after raw sludge conditioning by L-g-P15 extracted by a method according to an embodiment of the present invention;
FIG. 14 is a molecular diagram of an organic HPSEC after raw sludge conditioning by L-g-P20 extracted by a method of an embodiment of the invention;
FIG. 15 is a molecular diagram of an organic HPSEC extracted by the method of the embodiment of the invention after conditioning raw sludge with L-g-P30.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
A flocculant applied to sludge conditioning is a compound represented by a general formula (1).
Figure 59907DEST_PATH_IMAGE001
Specifically, "Lignin" in the general formula (1) represents a polyguaiacyl, polyviola-tyl or polyphenylyl group structure in the molecular structure of Lignin, and "Lignin" in the general formula (1)m，n，p，qEach represents a square bracket [ 2 ] in the respective general formula (1)]"the number of repeating units;m，n，p，qare all positive integers greater than or equal to 1.
Further, R in the general formula (1)1Independently selected from the general formula (2)
Figure 395074DEST_PATH_IMAGE002
General formula (3)
Figure 937044DEST_PATH_IMAGE003
General formula (4)
Figure 15859DEST_PATH_IMAGE004
General formula (5)
Figure 513836DEST_PATH_IMAGE005
General formula (6)
Figure 347800DEST_PATH_IMAGE006
General formula (7)
Figure 298439DEST_PATH_IMAGE007
One or more of them.
Further, R in the general formula (2)2R in the general formula (3)3R in the general formula (4)3R in the general formula (5)5R in the general formula (6)6R in the general formula (7)7Each independently selected from alkyl groups having 1 to 6 carbon atoms or alkyl groups having 7 to 10 carbon atomsA phenylalkyl group.
A method for synthesizing a flocculating agent applied to sludge conditioning comprises the following steps:
preparing a macroinitiator: dissolving 10-15 parts of lignin in 200-500 parts of organic ionic liquid, heating at 95-105 ℃ for 4.5-6 h, adding 70-80 parts of 2-bromoisobutyryl bromide in an ice-water bath after the lignin is safely dissolved, and reacting for 24h to form reaction liquid; and adding the reaction solution into 500-1000 parts of water at the speed of 0.01-0.1 part/min to obtain a precipitate, washing and filtering the precipitate with 500-1000 parts of diethyl ether for 3-5 times, and then carrying out vacuum freeze drying to obtain the macroinitiator.
Synthesizing a lignin-based flocculant: adding accurately weighed 1-1.5 parts of macroinitiator into 200-500 parts of organic ionic liquid to form an ionic solution reaction system; then, under the protection of ice water bath and nitrogen, respectively adding 0.01-0.02 part of copper bromide and 0.5-1.5 parts of reaction ligand into an ionic solution reaction system; adding a mixed solution of a reaction monomer and methanol in a mass ratio of 1: 2-1: 5 into the ionic solution reaction system at a speed of 0.01-0.1 part/min, and reacting for 4 hours at 15-30 ℃; then washing and filtering the mixture for 3-5 times by using 500-1000 parts of distilled water to obtain a reaction product; putting the reaction product into an acetone solvent, and extracting for 24 hours at 120 ℃ to obtain a white colloidal polymer; washing the white colloidal polymer with 500-1000 parts of distilled water, carrying out suction filtration for 3-5 times, and carrying out vacuum freeze drying to obtain the flocculant.
Wherein the lignin is one of high-boiling alcohol lignin, acetic acid lignin or cellulose enzymolysis lignin.
Wherein, the organic ionic liquid is one or more of fluorinated heterocyclic nitrogen compounds.
Wherein the reaction ligand is one or more of pentamethyldiethylenetriamine, 1,4,7,10, 10-hexamethyltriethylenetetramine, N1- (2- (dimethylamino) ethyl) -N2 ((dimethylamino) methyl) -N1, N2 dimethylethane-1, 2-diamine, N- (ethane-1, 2-diyl) bis (N, N ', N' -trimethylformamide) and N, N-methylenebis (N, N ', N' -trimethylformamide).
Wherein the reaction monomer is one or more of 3-methacryloxy-2-oxopropane sodium sulfonate, 3-methacryloxy propylamine methyl sodium sulfonate and O- ((methacryloxy) methyl) carbonyl sodium bisulfate.
Example one R2\R3\R4\R5\R6\R7
R in the general formula (2) of the present invention2R in the general formula (3)3R in the general formula (4)3R in the general formula (5)5R in the general formula (6)6R in the general formula (7)7Optionally, for example: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, pentyl, neopentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 2-dimethylbutyl, 3-dimethylbutyl, 2, 3-methylbutyl, phenyl, methylphenyl, dimethylphenyl, ethylphenyl, 1-methylethylphenyl, 2-methylethylphenyl, propylphenyl, butylphenyl, 1-methylpropylphenyl, 2-methylpropylphenyl, 3-methylpropylphenyl, 1-dimethylethylphenyl, 2-dimethylethylphenyl.
EXAMPLE two Lignin
The lignin used by the invention is one of high-boiling alcohol lignin, acetic acid lignin or cellulose enzymatic hydrolysis lignin.
The high-boiling alcohol lignin is obtained by steaming and extracting lignin raw material with high-boiling alcohol solvent such as 1, 4-butanediol, ethylene glycol, benzene alcohol, ethyl acetate, etc. The lignin raw material can be larch, wheat straw, Chinese alpine rush or coniferous grass and the like, and is obtained by the steps of drying, crushing, sieving and drying.
EXAMPLES Tri organic Ionic liquids
The organic ionic liquid is one or more of fluorinated heterocyclic nitrogen compounds. Specifically, fluorinated hetero nitrogen compounds are exemplified by: 1-allyl-3-methylimidazolyl fluoride, 3-methyl-1-vinyl-2, 5-dihydro-1H-imidazole-3-fluoride, 2-methyl-6, 7,8,8 a-tetrahydropyrrolo [1,2-a]Pyrazine fluoride, 1-methylpyrazine fluoride, 4-dimethylmorpholine fluoride, 4-methylmorpholine fluoride, 4-allyl-1-methyl-3, 4-dihydropyrazineOxazine fluoride, 5-allyl-1-methylpyrimidine fluoride, 3-allyl-1-methyl-2, 3-dihydropyrimidine fluoride, 4-methyl-3, 4-dihydro-2H-1, 4-oxazine fluoride, 4-methyl-4H-1, 4-oxazine fluoride, 2-allyl-4-methyl-4H-1, 4-oxazine fluoride. Preferred fluorinated heteronitrogen compounds are: 1-allyl-3-methylimidazolyl fluoride, 3-methyl-1-vinyl-2, 5-dihydro-1H-imidazole-3-fluoride, 2-allyl-4-methyl-4H-1, 4-oxazine fluoride, 4-allyl-1-methyl-3, 4-dihydropyrazine fluoride, 5-allyl-1-methylpyrimidine fluoride and 3-allyl-1-methyl-2, 3-dihydropyrimidine fluoride.
Example four characterization of lignin graft polymer synthesis
By using1The synthesized lignin-grafted polymer (L-g-P) was characterized by H-NMR and FTIR.
1H-NMR characterization was carried out using a 500 MHz DRX-500 nuclear magnetic resonance apparatus (Bruker, Germany). Respectively dissolving 5mg of Lignin (Lignin), 5mg of macroinitiator (Lignin-Br) and 5mg of Lignin graft polymer (L-g-P) in 0.6 mL of corresponding deuterated reagent (DMSO-d for Lignin, Lignin-Br and CDCl for Lignin-P)3Solvent d), respectively determining the amounts of Lignin, Lignin-Br and Lignin-g-P1H-NMR spectrum. FTIR characterization was determined using a Vector333 Fourier transform infrared spectrometer (Bruker, Germany), using a KBr tablet process to add a small amount of sample into KBr powder, and testing was performed by tablet pressing after the sample was ground to homogeneity.
GPC measurement was carried out by using a Water1515 type gel permeation chromatograph (Waters Co., U.S.A.) using THF as a mobile phase, dissolving 3ng of a sample in 1mL of THF, filtering the solution with a 2.5 μm organic membrane, and measuring the molecular weight.
FIG. 2, FIG. 3 and FIG. 4 are respectively a lignin, a lignin macroinitiator and a lignin graft polymer1H-NMR spectrum. Relative to fig. 2, multiple peaks appear at δ = 1.8-2.2 in fig. 3, with the main peaks being a (δ = 2.07) and b (δ = 2.1) and the others being interfering peaks, indicating phenolic hydroxyl groups and phenolic hydroxyl groups in the lignin molecule in this exampleThe alcoholic hydroxyl groups are respectively substituted by 2-bromo isobutyryl bromide, so that chemical shift is generated, and the synthesis of the lignin macroinitiator is proved.
With respect to fig. 2, a plurality of proton peaks appear in fig. 4, the proton peaks at chemical shifts δ =6.48 and δ =6.40 belong to the proton peaks on the carbon atoms at c and d in fig. 4, respectively, and the proton peaks at chemical shifts δ =4.43 and δ =6.48 represent CH at e and f in fig. 4, respectively2The proton peak at chemical shift δ =8.18 represents the proton on NH at g in fig. 4 and at chemical shift δ =4.94 represents CH at h in fig. 42The proton peak of (2) can be seen, and the spectrum is mainly embodied by the characteristic peak of the grafted side chain polymer.
FIG. 5 shows ATR-FTIR spectra of a lignin, a lignin macroinitiator, and a lignin graft polymer, which are reported in the present invention, after acylation of lignin, at 1741.81cm-1And 1257.3cm-1And a stretching vibration peak of carbonyl (C = O) and ether bond C-O-C is increased, which indicates that the acyl bromide group is grafted to the lignin and the synthesis of the macroinitiator Lingin-Br is completed. 2850cm from the spectrum of the graft copolymer-1And 2950cm-1In the presence of methylene (-CH)2) C-H stretching vibration absorption peaks are formed; 1140cm-1The characteristic peak is a C-O-C stretching vibration peak of open-chain aliphatic anhydride in a grafted side chain, which is obviously stronger than a Lignin-Br peak due to the introduction of a monomer, and the characteristic peaks prove that the synthesized polymer is obtained.
Example five thermodynamic characterization
TGA was measured using a Perkin Elmer TGA 4000 thermogravimetric analyzer (Perkin Elmer, USA). Placing 5mg of the sample in a crucible; the temperature was measured to 900 ℃ at a heating rate of 10K/min under a nitrogen atmosphere.
The thermal stability of a lignin and a lignin graft polymer synthesized by the present invention was measured by TGA in a nitrogen atmosphere, and the test results are shown in FIG. 6, wherein L-g-P10, L-g-P15, L-g-P20 and L-g-P30 respectively indicate that the molecular ratio of lignin to monomer in the graft copolymer is 1:10, 1:15, 1:20 and 1: 30. In FIG. 6, the thermal decomposition temperature of unmodified lignin was 189.9 ℃ when the thermal decomposition amount reached 2.5%, and the coke residual amount of aromatic ring chemical structure of lignin was 31.4% when the temperature was 900 ℃. When the thermal decomposition amount of the modified lignin reaches 2.5%, the thermal decomposition temperature is obviously improved compared with that of the unmodified lignin, the thermal decomposition temperatures of L-g-P10, L-g-P15, L-g-P20 and L-g-P30 are respectively 318.5 ℃, 334.2 ℃, 354.2 ℃ and 384.4 ℃, and the thermal decomposition temperature of the graft modified lignin is increased along with the increase of the length of the graft chain, and the liquid crystal phase transition temperature of the graft modified lignin is also slightly increased. In addition, the lignin-based liquid crystal polymer also has a lower residual amount of thermal decomposition than unmodified lignin. In general, the thermal stability of the lignin-based liquid crystal polymer subjected to grafting modification is improved, and the thermal decomposition temperature is also improved along with the increase of the molecular weight of the polymer.
EXAMPLE sixthly sludge Conditioning and dewatering Properties
Under the condition of room temperature, quickly adding a certain amount of lignin and L-g-P with different polymerization degrees into the sludge, wherein the adding amount is 0.01-0.5%, starting a magnetic stirrer, quickly stirring and reacting for 2 min, slowly stirring and reacting for 8min, and extracting supernatant and EPS for determination.
Measurement of sludge dewatering Property: the sludge Specific Resistance (SRF) represents the resistance per unit weight of sludge per unit filtration area when filtered under a certain pressure. And (4) dewatering the sludge as above, performing reduced pressure suction filtration to obtain a filter cake, and naturally drying. Spraying gold at fixed points, and taking SEM floc pictures. Obtaining corresponding fractal dimension D by graphical method by using Sand box counting methodf. The formula of the specific resistance of the sludge can be expressed as follows:
r = 2pA2b/μω
wherein p is a filtration pressure (kg. m)-2) (ii) a A is the filtration area (m)2) Mu is dynamic viscosity (kg · s · m) of the filtrate-2) (ii) a Omega is the weight of dry solids retained on the filter medium by a unit volume of filtrate filtered-3) (ii) a b is the slope of the line represented by the filtering equation t/V = bV + a, t is the filtering time(s); v is the volume of filtrate (m)3)。
Determination of the turbidity of the supernatant: after the sludge is conditioned by adding the flocculating agent, the filtrate obtained by suction filtration has certain impurities, the filtrate is turbid, the capability of the flocculating agent in removing colloidal particles, fine particles and some color-developing components in the sludge can be reflected, and the physical quantity directly reflects the conditioning effect of the sludge. The turbidity was measured directly with a turbidimeter.
The effect of the synthetic flocculant of the present invention applied to sludge dewatering is shown in fig. 7 and 8. As can be seen from FIG. 7, the specific resistance SRF of the sludge gradually decreases after the conditioning by the flocculating agent, and when the addition amount is in the addition amount range of 0.0005 to 0.001 g/g in terms of the percentage of the sludge weight, the specific resistance SRF value of the sludge sharply decreases with the increase of the addition amount, and the SRF value after being more than 0.001 g/g does not obviously increase with the increase of the addition amount. From fig. 8, it can be seen that the change rule of the water content of the conditioned mud cake is basically consistent with the change of the sludge Specific Resistance (SRF). The analysis shows that the sludge dewatering performance is continuously enhanced along with the increase of the polymerization degree of the flocculating agent, the coagulation effect of the L-g-P30 is optimal, the sludge dewatering performance is best, and compared with the traditional flocculating agent, the reasonable adding amount of the flocculating agent is about 0.001 g/g and is far lower than the adding amount of the traditional flocculating agent which is 0.01-0.03 g/g. Fig. 9 shows the turbidity of the filtrate after the sludge conditioning by different flocculant adding amounts, and it can be seen that the turbidity of the filtrate after the flocculant conditioning is remarkably reduced, the whole turbidity is reduced with the increase of the flocculant adding amount, the trend is the same as the sludge specific resistance SRF, and the turbidity of the filtrate is finally reduced to 12.84NTU by the sludge after the L-g-P30 conditioning.
Example effects of heptaflocculation on sludge TOC
Total Organic Carbon (TOC) is measured by a TOC-L CPN type determinator (Shimadzu) and a 680 ℃ combustion catalytic oxidation method, so that the method not only can effectively oxidize easily decomposed low molecular weight organic compounds, but also can oxidize insoluble and macromolecular organic compounds which are difficult to decompose.
As can be seen from the graph 10, compared with the original sludge which is conditioned by the flocculating agent, the content of the soluble organic carbon (DOC, reflected by the change of TOC) in the sludge is slightly reduced (0.35-1.32 mg/L), when the addition amount reaches 0.001 g/g, the DOC content is stable, compared with the DOC content conditioned by 4 kinds of the flocculating agents, the DOC content conditioned by L-g-P30 is the lowest, and then L-g-P20, L-g-P15 and L-g-P10 are consistent with the change rule of the SRF value of the sludge, and the flocculating agent has little effect of removing the total organic carbon.
EXAMPLE eight Effect of flocculation on EPS
50mL of sludge is taken in a centrifuge tube at 3000 r.min-1Centrifuging for 10min at the rotating speed of (1), collecting supernatant (I), adding 15mL of 0.05% NaCl solution into the rest precipitate, rapidly stirring in a vortex oscillator, and then rotating at 150 r.min in a shaking table-1Horizontally shaking for 10min, then at 5000 r.min-1Centrifuging for 10min at the rotating speed of (1), and collecting sludge supernatant liquid; adding 15mL of 0.05% NaCl solution into the precipitate, rapidly stirring in vortex oscillator, heating in 60 deg.C water bath for 30min, and then heating at 5000 r.min-1Centrifuging for 20min at the rotating speed of (3), and collecting supernatant liquid (c). And combining the supernatant I, the supernatant II and the supernatant III, and filtering the mixture through a filter membrane of 0.45 mu m to be tested.
High Performance Size Exclusion Chromatography (HPSEC) a Waters liquid chromatography system consisting of a Waters 2487 dual wavelength absorption detector, a Waters 1525 pump. The column used for the separation was TSKgelG3000 SWXL. The mobile phase is 5 mol.L-1Phosphate buffer and 0.01 mol.L-1Passing NaCl solution through 0.22 μm filter membrane, and performing ultrasonic treatment for 15min at mobile phase flow rate of 1.0 mL/min-1The measurement wavelength was 254 nm, and the injection volume was 200. mu.L. Sodium polystyrene sulfonate (PSS) as a standard substance of relative molecular mass, PSS used in the marked line has relative molecular mass of 1.8 × 103、4.2×103、6.5×103。
FIG. 11, FIG. 12, FIG. 13, FIG. 14 and FIG. 15 are the molecular maps of HPSEC, which is the organic matter in the raw sludge extracted by the above-mentioned method, the L-g-P10 treated group, the L-g-P15 treated group, the L-g-P20 treated group and the L-g-P30 treated group, respectively. Wherein the molecular peaks at relative molecular weights > 5000 generally represent proteins and polysaccharides; the molecular weight component is 1000-5000, and is mainly humic acid and a low molecular weight component; the molecular weight is less than 1000, and the material is a micromolecular framework material. FIGS. 11 to 15 show that the binding EPS, in which the molecular peaks at 60000, 700000 and 1200000 are mainly macromolecular, are removed together with silt and other inorganic substances in the sludge by flocculation, while the small-molecular proteins, polysaccharides and humic acids represented by the molecular peaks at 1000, 1200, 2500, 3500, 4000, 25000 and 40000 of medium molecular weight are not removed by flocculation and remain in the supernatant after flocculation.
Further, the extracted protein, polysaccharide, humic acid in the EPS solution were determined by BCA method, anthrone colorimetric method and ZBG21005-87 method, respectively, and the results are shown in Table 1. Table 1 shows that the removal rate of protein, carbohydrate and humic acid is not high, and is between 3.53% and 14.35%.
TABLE 1
Group of Protein (g/kg) Carbohydrate (g/kg) Humic acid (g/kg) Hg(mg/kg) Cu(mg/kg) Pb(mg/kg) Cr(mg/kg)
Control group 87.31±4.76 234.46±37.63 47.15±1.78 175.09±12.63 278.41±35.26 217.68±53.62 28.74±1.35
L-g-P10 84.23±3.64 232.26±41.26 45.26±1.25 163.15±23.65 236.37±41.29 185.31±46.28 21.26±1.74
L-g-P15 78.28±5.26 230.32±32.06 44.36±2.07 123.74±32.46 214.45±57.32 134.72±62.35 18.47±2.43
L-g-P20 75.37±4.19 228.51±41.67 44.25±1.26 87.26±27.45 185.31±62.78 102.26±72.03 14.32±2.21
L-g-P30 74.78±3.67 227.75±23.46 43.79±2.31 67.74±23.54 174.52±58.34 87.48±25.06 12.18±184
Example nine removal of heavy metals from sludge
ICP-AES method: weighing 0.1 g of sample, placing the sample in a microwave digestion tank, adding 6mL of nitric acid, 2mL of hydrochloric acid, 3mL of hydrofluoric acid and 1mL of hydrogen peroxide, and placing the sample in a microwave digestion instrument for digestion. And taking out after cooling, transferring the sample to a polytetrafluoroethylene beaker by using a small amount of water, adding 3mL of perchloric acid, smoking until the sample is nearly dry, taking down the cooling beaker, adding 5mL of nitric acid to dissolve residues, cooling, fixing the volume to a 100mL volumetric flask, and shaking up uniformly. If insoluble matter exists, dry filtering. And (3) measuring the contents of mercury, copper, lead and chromium in the filtrate after the sludge neutralization conditioning by adopting a Plasma 2000 full-spectrum inductively coupled Plasma spectrometer.
As can be seen from Table 1, the removal rates of mercury, copper, lead and chromium were the highest for L-g-P30, and were 61.31%, 37.32%, 59.81% and 57.62%, respectively.
Through the sixth embodiment, the seventh embodiment, the eighth embodiment and the ninth embodiment, the sludge conditioned by the flocculant synthesized by the invention has good dewatering performance, the content of organic carbon, total protein, total sugar and humic acid in the conditioned filtrate is not obviously reduced, and only a small part of macromolecular bound EPS is taken away with silt and other inorganic matters in the sludge along with flocculation; the removal rates of the L-g-P30 on mercury, copper, lead and chromium in the filtrate are the highest and are respectively 61.31%, 37.32%, 59.81% and 57.62%; the flocculant still has a large amount of organic matters in the filtrate after conditioning the sludge, and can remove heavy metals in the sludge to a certain extent, thereby providing a brand new solution for the recycling of the filtrate and the utilization of waste.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. The flocculant applied to sludge conditioning is characterized in that the flocculant is a compound represented by a general formula (1);
Figure FDA0003353655780000011
"Lignin" in the general formula (1) represents a polyguaiacyl group, a polyvioletranyl group or a polyprenyl group in a molecular structure of Lignin, and m, n, p, q in the general formula (1) respectively represent square brackets "[ term ], [ in the respective general formula (1)]"the number of repeating units; the m, n, p and q are positive integers which are more than or equal to 1, and R in the general formula (1)1Independently selected from the general formula (2)
Figure FDA0003353655780000012
General formula (3)
Figure FDA0003353655780000013
General formula (4)
Figure FDA0003353655780000014
General formula (5)
Figure FDA0003353655780000015
General formula (6)
Figure FDA0003353655780000016
General formula (7)
Figure FDA0003353655780000017
One or more of the above; r in the general formula (2)2R in the general formula (3)3The above-mentionedR in the general formula (4)4R in the general formula (5)5R in the general formula (6)6R in the general formula (7)7Each independently selected from alkyl with 1-6 carbon atoms or phenylalkyl with 7-10 carbon atoms;
the method comprises the following steps:
preparing a macromolecular initiator: dissolving 10-15 parts of lignin in 200-500 parts of organic ionic liquid, heating at 95-105 ℃ for 4.5-6 h, adding 70-80 parts of 2-bromoisobutyryl bromide in an ice-water bath at 4 ℃ after the lignin is safely dissolved, and reacting for 24h to form reaction liquid; adding the reaction solution into 500-1000 parts of water at the speed of 0.01-0.1 part/min to obtain a precipitate, washing and filtering the precipitate with 500-1000 parts of diethyl ether for 3-5 times, and then carrying out vacuum freeze drying to obtain a macroinitiator;
synthesis of lignin-based flocculant: adding accurately weighed 1-1.5 parts of the macroinitiator prepared in the first step into 200-500 parts of the organic ionic liquid to form an ionic solution reaction system; then, respectively adding 0.01-0.02 part of copper bromide and 0.5-1.5 parts of reaction ligand into the ionic solution reaction system under the protection of ice-water bath at 4 ℃ and nitrogen; adding a mixed solution of a reaction monomer and methanol in a mass ratio of 1: 2-1: 5 into the ionic solution reaction system at a speed of 0.01-0.1 part/min, and reacting for 4 hours at 15-30 ℃; then washing and filtering the mixture for 3-5 times by using 500-1000 parts of distilled water to obtain a reaction product; putting the reaction product into an acetone solvent, and extracting for 24 hours at 120 ℃ to obtain a white colloidal polymer; and washing the white colloidal polymer with 500-1000 parts of distilled water, carrying out suction filtration for 3-5 times, and carrying out vacuum freeze drying to obtain the flocculant.
2. The method for synthesizing the sludge conditioning flocculant according to claim 1, wherein the lignin in the step (i) is one of high-boiling alcohol lignin, acetic acid lignin or cellulose enzymolysis lignin.
3. The synthesis method applied to the sludge conditioning flocculant according to claim 1, wherein the organic ionic liquid in the step (i) is one or more of fluorinated heterocyclic nitrogen compounds.
4. The synthesis method applied to the sludge conditioning flocculant according to claim 1, characterized in that 24-60 parts of one or more of pyrrole, imidazole, pyridine, pyridazine or pyrazine are added to the reactant in the step (i).
5. The method for synthesizing flocculant for sludge conditioning according to claim 1, wherein the reaction ligand in the step (c) is one of pentamethyldiethylenetriamine, 1,4,7,10, 10-hexamethyltriethylenetetramine, N1- (2- (dimethylamino) ethyl) -N2 ((dimethylamino) methyl) -N1, N2 dimethylethane-1, 2-diamine, N- (ethane-1, 2-diyl) bis (N, N ', N' -trimethylformamide), N-methylenebis (N, N ', N' -trimethylformamide).
6. The flocculant applied to sludge conditioning and the synthesis method according to any one of claims 1 to 4, wherein the reaction monomer in the step (II) is represented by a general formula (8)
Figure FDA0003353655780000021
And (4) showing.
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