CN113797590A

CN113797590A - Method for regenerating and recycling fluid salt-tolerant flocculating agent

Info

Publication number: CN113797590A
Application number: CN202111236537.4A
Authority: CN
Inventors: 史玉琳; 李易诺; 魏婷婷; 陈龙
Original assignee: Shihezi University
Current assignee: Shihezi University
Priority date: 2021-10-23
Filing date: 2021-10-23
Publication date: 2021-12-17

Abstract

The invention discloses a method for regenerating and recycling a fluid salt-resistant flocculating agent. The method comprises the following steps: adjusting the pH of the solution to release the salt tolerant flocculant from the flocculated sludge; the water-salt system separates the solid dye and the fluid salt-tolerant flocculant; the recycling of the fluid salt-tolerant flocculant is realized by directly separating the fluid salt-tolerant flocculant and the solid dye from the concentrated mixed solution by utilizing the solubility difference of the dye and the flocculant in the saline water, so that the recovery and the recycling of the flocculant fluid are realized. The problem of the high concentration pollutant waste liquid that traditional drip washing mode regeneration desorption silt produced handles is solved, also the production of the maximum degree flocculation silt has simultaneously been reduced. In addition, the fluid salt-tolerant flocculating agent and pollutants are repeatedly used, so that the flocculation operation cost of the wastewater is reduced, the problem of safe treatment of the flocculated sludge is effectively solved, valuable pollutants in the wastewater can be recovered, and the method has important contribution to realizing zero emission of a flocculation operation unit.

Description

Method for regenerating and recycling fluid salt-tolerant flocculating agent

Technical Field

The invention relates to the technical field of textile printing and dyeing wastewater treatment and flocculation sludge treatment, in particular to a method for regenerating and recycling a fluid salt-resistant flocculant.

Background

Flocculation/coagulation is an effective cleaning technology in environmental pollution remediation, but the problem that a large amount of sludge cannot be safely disposed still exists. The production of chemical sludge, the major by-product of the flocculation process, is almost inevitable due to the excessive use of flocculants. If the used flocculant can be regenerated and recycled in the flocculation process, the method is a great step of the flocculation device towards zero discharge. In addition, the recycling of the waste flocculants also enhances the resource utilization of the materials (mainly flocculants and valuable pollutants). Therefore, direct recovery of the flocculant from the flocculated sludge can substantially reduce flocculation costs, minimize the production of flocculated sludge, and enable the recovery and utilization of valuable contaminants (e.g., heavy metal ions, valuable dyes, etc.).

In the traditional flocculant adsorption-desorption cycle process, pollutants are only transferred from sludge to leacheate in the form of concentrated solution, and the method cannot completely eliminate the pollutants and further cannot recycle the pollutants. If specific pollutants are directly separated from the eluent, the pollutants can be prevented from being accumulated as concentrated waste liquid, the water treatment agent can be recycled, and the wastewater treatment cost is reduced. Since most synthetic dyes are very sensitive to ionic strength, salting-out crystallization is a widely used technique for dye separation and purification in industry. In contrast, zwitterionic polyelectrolytes exhibit unique salt tolerance properties, and the polymers remain extremely soluble in high salt solutions. Thus, by utilizing the solubility differences of the zwitterionic flocculant and the dye in the brine, effective separation of the solid dye from the fluid flocculant can be achieved.

Disclosure of Invention

The invention aims to provide a method for regenerating and recycling a fluid salt-tolerant flocculant, which comprises the steps of adjusting the pH value of a solution to release the salt-tolerant flocculant from flocculated sludge, separating a solid dye from a water-salt system, and recycling the fluid salt-tolerant flocculant. By utilizing the solubility difference of the dye and the flocculant in the saline water, the fluid salt-tolerant flocculant and the solid dye can be directly separated from the concentrated mixed liquor. In the method, salting-out precipitation can occur after inorganic salt is added, but the amphoteric flocculant generally has good salt resistance. Therefore, the effective separation of the solid dye and the fluid salt-resistant flocculant is realized by utilizing the obvious solubility difference of the two substances in the salt solution, the problems of secondary enrichment and pollution of pollutants in high-concentration leacheate in the traditional leaching mode are solved, the fluid flocculant can be repeatedly used in a new decolorization experiment, the consumption of a fresh flocculant is effectively reduced, the problem that a large amount of sludge cannot be safely treated in the flocculation process is solved, and the possibility is opened up for the recovery and reutilization of the flocculant and valuable pollutants. In addition, the regenerated fluid salt-tolerant flocculant has good stability in continuous regeneration-reuse circulation, still maintains high-level dye wastewater decolorization effect and regeneration stability, and has excellent wastewater treatment effect.

The invention relates to a method for regenerating and recycling a fluid salt-resistant flocculating agent, which comprises the following steps:

adjusting the pH of the solution to release the salt tolerant flocculant from the flocculated sludge:

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of printing and dyeing wastewater]-triazine-6-starch ethers, diluted 1M H₂SO₄Or adjusting pH to 0.2-9 with 1M HCl aqueous solution, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μ M to collect flocculated sludge after decolorizing active brilliant red K-2BP in printing and dyeing wastewater is completed, placing flocculated sludge in beaker containing 100mL purified water, adjusting pH to 1-11 with 1M NaOH or 1M HCl aqueous solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein salt-tolerant flocculant is 2, 4-bis (p-aminobenzoate) - [1,3,5]]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 0.05-2: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 1g-22.5g of inorganic salt sodium sulfate or sodium chloride into 100mL of the concentrated 10-fold mixed solution prepared in the step a, wherein the salt concentration is 10-225g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2-3cm and the pore diameter of 30-50 mu m, measuring the volume of filtrate passing through the effective area of the common medium-speed filter paper by using a 100mL measuring cylinder within 5-30min, and collecting the filtrate and a filter cake to obtain a renewable fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether and salted solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. c, taking the fluid salt-resistant flocculant obtained in the step b, namely 2, 4-di (p-aminobenzoic acid radical) - [1,3, 5-]0.5mL of triazine-6-starch ether, diluting by 100 times, and calculating a salt-resistant flocculant 2, 4-di (p-aminobenzoic acid base) - [1,3,5] in the filtrate by an ultraviolet spectrophotometer]-concentration of triazine-6-starch ether, flocculating agent 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-bis (p-aminobenzoic acid) with salt tolerance of the regenerated fluid]-triazine-6-starch ether) and reactive brilliant red K-2BP in printing and dyeing wastewater in a mass ratio of 1:2, and then diluted 1M H₂SO₄Or adjusting pH to 1 with 1M HCl aqueous solution, magnetically stirring for 2min, and performing flocculation precipitation with active bright red K-2BP to obtain regenerated fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5]Recycling of the triazine-6-starch ether.

The invention relates to a method for regenerating and recycling a fluid salt-resistant flocculant, wherein the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether involved in the method is obtained from the patent application number 201910403052.6. The structural formula is as follows:

the preparation method of the salt-tolerant flocculant comprises the following steps:

a. pouring cyanuric chloride into a three-neck round-bottom flask, adding 100ml of deionized water, stirring at 0 ℃, dissolving p-aminobenzoic acid and sodium hydroxide in 50ml of deionized water, dropwise adding the mixture into the three-neck round-bottom flask, continuously stirring at 0-5 ℃, reacting for 30min, heating to room temperature, stirring for reaction for 3h, adjusting the pH to 4.6 by using 3M HCL to obtain white precipitate, performing suction filtration, removing most of water from a filter cake by using a blast oven at 60 ℃, drying for 6 h by using a vacuum drying oven at 60 ℃, and grinding to obtain a white intermediate 2, 4-bis (p-aminobenzoate) -6-chloro- [1,3,5] -triazine, wherein the mass ratio of p-aminobenzoic acid to cyanuric chloride is 1:1.5, and the mass ratio of sodium hydroxide to cyanuric chloride is 1: 1.7;

or dissolving p-aminobenzoic acid, cyanuric chloride and sodium hydroxide in a mixed solution of acetone and water, continuously stirring at the temperature of 0-5 ℃, reacting for 30min, heating to room temperature, stirring for reacting for 3h, adjusting the pH to 4.6 by using 3M HCL to obtain white precipitate, then performing suction filtration, removing most of water from a filter cake by using a blast oven at 60 ℃, drying for 6 h by using a vacuum drying oven at 60 ℃, and grinding to obtain a white intermediate 2, 4-bis (p-aminobenzoate) -6-chloro- [1,3,5] -triazine, wherein the volume ratio of acetone to water is 1: 1;

b. adding starch, sodium hydroxide and the intermediate 2, 4-di (p-aminobenzoic acid) -6-chloro- [1,3,5] -triazine obtained in the step a into a four-neck flask according to the mass ratio of 2, 4-di (p-aminobenzoic acid) -6-chloro- [1,3,5] -triazine to starch of 1:6.7-13.4 and the mass ratio of sodium hydroxide to starch of 1:1.7-3, adding 100mL of dimethyl sulfoxide, stirring, stirring for 10h at the temperature of 130 ℃, cooling to room temperature, adding 100mL of absolute ethyl alcohol, stirring for 10min, carrying out suction filtration to obtain a precipitate, and carrying out vacuum drying on a filter cake at the temperature of 60 ℃ for 11h to obtain the salt-resistant flocculant 2, 4-bis (p-aminobenzoic acid yl) - [1,3,5] -triazine-6-starch ether.

The invention relates to a method for regenerating and recycling a fluid salt-resistant flocculant, which realizes the color removal of printing and dyeing wastewater and the regeneration and recycling evaluation of the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP):

fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5] is added according to the mass ratio of 1:1000]Mixing triazine-6-starch ether (STZP) with water, adjusting the pH to 10 by using a 1M NaOH aqueous solution, and magnetically stirring until the mixture is completely dissolved to obtain a fluid salt-resistant flocculant STZP; then diluted 1M H₂SO₄Or 1M HCl aqueous solution to adjust the pH to 1To obtain stable and invertible hydrogel, and then regulating pH of the solution to 10 with 1M NaOH aqueous solution to obtain clear fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5]-triazine-6-starch ether (STZP);

the obtained fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5]]-triazine-6-starch ether (STZP), with the addition of 1g to 22.5g of the inorganic salt NaCl or Na₂SO₄Magnetically stirring for 5min with salt concentration of 10-225g/L, filtering with common medium-speed filter paper with radius of 2-3cm and pore diameter of 30-50 μm at normal pressure, and collecting filtrate A;

dissolving 2g of reactive brilliant red K-2BP into 1L of aqueous solution to simulate printing and dyeing wastewater, taking 50mL of prepared printing and dyeing wastewater, and adding 1g-22.5g of inorganic salt NaCl or Na₂SO₄Magnetically stirring for 5min with salt concentration of 10-225g/L, filtering with common medium-speed filter paper with radius of 2-3cm and pore diameter of 30-50 μm at normal pressure, and collecting filtrate B;

measuring the Zeta potential of a salt-tolerant flocculating agent STZP in the filtrate A and the Zeta potential of active brilliant red K-2BP in the filtrate B by using a nanoparticle Zeta potential analyzer;

measuring the concentration of a salt-tolerant flocculant STZP in the filtrate A and the concentration of active bright red K-2BP in the filtrate B by using an ultraviolet spectrophotometer, and calculating the percentage of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) in the filtrate A and the filtrate B in the fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) before salting-out separation and the percentage of the active bright red K-2BP in the filtrate in the simulated printing and dyeing wastewater before salting-out separation; recovering and reusing fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP):

fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5]]125g/L NaCl or 155g/L Na was added to the triazine-6-starch ether (STZP)₂SO₄Magnetic stirring for 5min, filtering with common medium speed filter paper with radius of 2-3cm and pore diameter of 30-50 μm at normal pressure to obtain regenerated fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5]-triazine-6-starch ethers (S)TZP) and is put into the reactive brilliant red K-2BP wastewater, thereby realizing the color removal of the printing and dyeing wastewater and the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoate) - [1,3,5]]Regeneration and recycling of-triazine-6-starch ether (STZP).

The invention has the beneficial effects that: the method of the invention realizes the effective separation of the salt-tolerant flocculating agent with the same salt tolerance as the fluid salt-tolerant flocculating agent 2, 4-di (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) in the sludge and the dye, can recover and reuse the fluid salt-tolerant flocculating agent, can directly separate specific pollutant solids from the concentrated mixed solution, can realize the effective separation of the solid dye and the fluid salt-tolerant flocculating agent, solves the problem of secondary pollution of pollutants in high-concentration leacheate in the traditional leaching mode, can be repeatedly used for many times, effectively solves the problem that a large amount of sludge cannot be safely treated in the flocculation process, and opens up the possibility for the recovery and reuse of the fluid salt-tolerant flocculating agent and valuable pollutants, meanwhile, the regenerated fluid salt-resistant flocculant has good stability in continuous regeneration-reuse circulation, still maintains high-level flocculation and regeneration effects, and is a great step for zero discharge of the fluid salt-resistant flocculant in printing and dyeing wastewater.

Drawings

FIG. 1 is a schematic diagram showing the salt tolerance of the recycling of amphoteric polyelectrolyte in high concentration printing and dyeing wastewater in example 1 of the present invention.

FIG. 2 shows the maximum absorption wavelength λ of the reactive brilliant red K-2BP solution in example 1 of the present invention_maxA standard curve chart (a) of the concentration C and the absorbance A at 537.0nm, a standard curve chart (b) of the concentration C and the absorbance A at 290.0nm of a reactive bright red K-2BP solution and a standard curve chart (b) of a salt-tolerant flocculating agent STZP solution at the maximum absorption wavelength lambda_maxStandard curve (C) of concentration C versus absorbance a at 290.0 nm.

FIG. 3 is a diagram showing the reversible conversion of the external pH change to the sol-gel process of the flocculant STZP in a one-component system in example 1 of the present invention.

FIG. 4 is a diagram showing the solution properties of the fluid salt-tolerant flocculant STZP in example 1 of the present invention, which is a diagram showing the influence of high ionic strength (NaCl) on the transmittance of the flocculant STZP solution (a), a diagram showing the relationship between the viscosity and shear rate of the flocculant STZP at a high NaCl concentration (b), a diagram showing the influence of high ionic strength (NaCl) on the Zeta potential and residual amount of the flocculant STZP at a high concentration (c), and a diagram showing the Zeta potential and residual amount of active Brilliant red K-2BP at a high NaCl concentration (d), respectively.

Fig. 5 is a diagram of the adsorption performance of the fluid salt-tolerant flocculant STZP in example 1 of the present invention, which is a diagram of directional decoloring of the fluid salt-tolerant flocculant STZP triggered by pH (a), a diagram of directional decoloring of the active bright red K-2BP by the concentration of the fluid salt-tolerant flocculant STZP (b), and a diagram of the influence of the fluid salt-tolerant flocculant STZP on the decoloring performance of the active bright red K-2BP under different NaCl concentrations (c), respectively.

Fig. 6 is a graph (a) of the release rate of the fluid salt-tolerant flocculant STZP from the flocculated sludge at different pH values in example 1 of the present invention, a graph (b) of the retention rate of a common medium-speed filter paper with a pore size of 30-50 μm in a high concentration NaCl/water mixture on a bi-component 1g/L fluid salt-tolerant flocculant STZP and 2g/L active bright red K-2BP, a graph (c) of the effect of a high NaCl concentration on the separation performance of the active bright red K-2 BP/flocculant STZP mixture at pH 10, and a graph (d) of the decolorization efficiency of the fluid salt-tolerant flocculant STZP for 5 consecutive adsorption/desorption cycles.

FIG. 7 is a graph (a) showing the effect of low NaCl concentration on the transmittance of the fluid salt-tolerant flocculant STZP solution, a graph (b) showing the relationship between the viscosity and the shear rate of the 1g/L flocculant STZP at low NaCl concentration, a graph (c) showing the effect of the low NaCl concentration on the Zeta potential and the residual amount of the fluid salt-tolerant flocculant STZP, and a graph (d) showing the Zeta potential and the residual amount of reactive bright red K-2BP at low NaCl concentration.

FIG. 8 is a graph showing the retention rate of ordinary medium-speed filter paper with a pore size of 30-50 μm to two-component 1g/L fluid salt-tolerant flocculant STZP and 2g/L active bright red K-2BP in a low-concentration NaCl/water mixture according to the present invention (a), and a graph showing the influence of low-concentration NaCl on the separation performance of the mixed liquid of active bright red K-2 BP/flocculant STZP at pH 10 (b).

FIG. 9 shows Na of the present invention₂SO₄The influence of the concentration on the transmittance of the fluid salt-tolerant flocculant STZP solution is shown in the figure (a), in Na₂SO₄Fluid salt-tolerant flocculant STZP pair under concentrationInfluence of the decolorizing performance of reactive brilliant red K-2BP (b).

FIG. 10 is a graph of viscosity versus shear rate for a 1g/L flocculant STZP of the present invention under salt-free conditions.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to specific examples.

Example 1

Adjusting the pH of the solution to release the salt tolerant flocculant STZP from the flocculated sludge:

a. at room temperature, taking 1L of active bright red K-2BP wastewater which is prepared in advance and is 0.2g/L, adding a fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) into the dye wastewater, wherein the mass ratio of the fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) to the active bright red K-2BP in the printing and dyeing wastewater is 1:2, controlling the concentration of the fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) to be 0.05g/L, and adjusting the pH of the solution to be 0.2 by adding 1M HCl; after fully stirring, the fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) is subjected to sol-to-gel conversion, the decoloration and precipitation of active brilliant red K-2BP are completed, the generated flocculated sludge is filtered and collected through a 0.45-micron microfiltration membrane, 0.2g of flocculated sludge is placed in a beaker containing 100mL of purified water, the pH of the solution is adjusted to 10 by using a 1M NaOH aqueous solution, and the solution is stirred for 30min to realize the complete release of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) and the active brilliant red K-2BP, so as to obtain a mixed solution concentrated by 10 times; the release rate of the flocculant and the reactive brilliant red K-2BP is accurately evaluated by measuring the content of a salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) - [1,3,5] -triazine-6-starch ether (STZP) and the reactive brilliant red K-2BP in the concentrated mixed solution, and the calculation formula is as follows:

wherein, C_r,eIs a salt-tolerant flocculating agent STZP or active pigment after releaseConcentration of red K-2BP, g/L; v is volume, L; m is_r,0The total mass g of a salt-tolerant flocculating agent STZP and active bright red K-2BP contained in the flocculated sludge;

separating solid dye and fluid salt-tolerant flocculant STZP by a water-salt system:

b. b, adding 15g of inorganic salt sodium chloride into the 10-time concentrated mixed solution obtained in the step a, wherein the salt concentration is 150g/L, magnetically stirring for 5min, and filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 30 mu m to obtain a renewable fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) and a salting-out solid dye; the method comprises the following steps of evaluating the recovery performance of a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) - [1,3,5] -triazine-6-starch ether (STZP) and the retention rate of active bright red K-2BP by taking a filtrate, and calculating the percentage of the salt-tolerant flocculant STZP and the active bright red K-2BP in the filtrate in a concentrated mixed solution before separation, wherein the calculation formula is as follows:

wherein, C_s,0And C_s,eRespectively representing the equilibrium concentration of active bright red K-2BP or salt-tolerant flocculant STZP before and after salting out, g/L;

and measuring the effective area of the filter membrane passing through the measuring cylinder within 5min²The volume of filtrate of (a); then obtaining active bright red K-2BP and salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5] in the filtrate by an ultraviolet spectrophotometer]Content of-triazine-6-starch ether (STZP), g/L, reactive bright red K-2BP and fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The permeation flux and separation factor (α) of triazine-6-starch ether (STZP) are calculated by equation (3) and equation (4):

wherein, C_i,eAnd C_j,eRespectively containing active bright red K-2BP and fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5] in penetrating fluid]-concentration of triazine-6-starch ether (STZP), g/L; c_i,0And C_j,0Respectively comprises active bright red K-2BP and fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5] in raw material liquid]-concentration of triazine-6-starch ether (STZP), g/L; t is time, h; a is the effective area, m²(ii) a V is the filtrate volume, L;

recycling the fluid salt-tolerant flocculant STZP:

c. diluting the fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether (STZP) obtained in the step b by 100 times in 0.5mL under the NaCl concentration of 155g/L, calculating the concentration of the active bright red K-2BP and the fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether (STZP) in the filtrate by an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether (STZP) and new dye wastewater in a mass ratio of 1:2, adjusting the pH to 1 by using a diluted 1M HCl aqueous solution, and magnetically stirring for 2min, performing activated brilliant red K-2BP flocculation and precipitation, and then filtering and collecting flocculated sludge through a microporous filter membrane of 0.45 mu m; the flocculation capacity of the regenerated fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) is evaluated by taking the filtrate, and the percentage of the content of the reactive bright red K-2BP in the filtrate in the wastewater before flocculation is calculated by equation (5), wherein the calculation formula is as follows:

wherein, C₀And C_eRespectively representing the initial concentration and the equilibrium concentration of the reactive brilliant red K-2BP, g/L.

Example 2

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of pre-prepared active bright red K-2BP wastewater of 0.2g/L, adjusting the pH to 6 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the active bright red K-2BP is decolored, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 7 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 15.5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 155g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 35 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 20min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. and (c) taking 0.5mL of the fluid salt-tolerant flocculant obtained in the step (b), diluting by 100 times, calculating the concentration of the salt-tolerant flocculant in the filtrate by using an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater in a mass ratio of 1:2, adjusting the pH to 1 by using a diluted 1M HCl aqueous solution, magnetically stirring for 2min, and performing active bright red K-2BP flocculation and precipitation to realize the salt-tolerant recycling of the regenerated fluid flocculant.

Example 3

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of pre-prepared active bright red K-2BP wastewater of 0.2g/L, adjusting the pH to 9 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the active bright red K-2BP is decolored, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 11 with 1M NaOH water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 17.5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 175g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 25min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 4

a. at room temperature, taking 1L of pre-prepared active brilliant red K-2BP wastewater of 0.2g/L, adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether, adjusting the pH to 9 by using a diluted 1MHCl aqueous solution, magnetically stirring for 2min, finishing flocculation after the decolorization of the active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 10 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 20g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 200g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 30min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 5

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of pre-prepared active bright red K-2BP wastewater of 0.2g/L, adjusting the pH to 9 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the active bright red K-2BP is decolored, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 10 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 22.5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 225g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of-50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 30min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. and (c) taking 0.5mL of the fluid salt-tolerant flocculant obtained in the step (b), diluting by 100 times, calculating the concentration of the salt-tolerant flocculant in the filtrate by using an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater in a mass ratio of 1:2, adjusting the pH to 1 by using a diluted 1MHCl aqueous solution, magnetically stirring for 2min, and performing active bright red K-2BP flocculation and precipitation to realize the salt-tolerant recycling of the regenerated fluid flocculant.

The method of examples 1-5 is adopted to realize the regeneration and recycling of the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) at high sodium chloride concentration of 150-; wherein, FIG. 1 is a schematic diagram of the recovery and reuse of the salt-resistant amphoteric polyelectrolyte in 150-225g/L high-concentration printing and dyeing wastewater in examples 1-5; as shown in fig. 1: under the alkaline condition, carboxylic acid is protonated, and a salt-tolerant flocculating agent STZP can coexist with dye molecules in a uniform miscible state and then is gelatinized by adding acid; the in-situ gelation of the salt-tolerant flocculant STZP can completely remove the dye in water; then, collecting flocculated sludge, adding a small amount of water to form a suspension, adjusting the pH of the solution, and releasing the dye and the salt-tolerant flocculant STZP into the water again through the reversible gel-sol transformation induced by the pH to form a highly concentrated homogeneous solution; adding a large amount of inorganic salt into the coexistence system, precipitating the dye under the salting-out effect, keeping high solubility of the salt-tolerant flocculant STZP in water, and separating the solid dye from the fluid salt-tolerant flocculant STZP by adopting a filtering mode;

FIG. 2 is a standard graph of concentration C and absorbance A of the dye solution and fluid salt tolerant flocculant STZP of examples 1-5; as shown in fig. 2 (a): dye solution at maximum absorption wavelength lambda_maxThe degree of fit of the concentration C at 537.0nm to the absorbance A is R²0.9998, which shows that the relationship between the concentration of the dye solution and the absorbance is linear, can be used to determine the residual amount of the dye in the wastewater; as shown in fig. 2 (b): the degree of fit of the concentration C of the dye solution to the absorbance A at a wavelength λ of 290.0nm is R²0.9997; as shown in fig. 2 (c): fluid salt-tolerant flocculant STZP at maximum absorption wavelength lambda_maxThe degree of fit of the concentration C at 290.0nm to the absorbance A is R²The relation between the concentration of the fluid salt-tolerant flocculant STZP and the absorbance is linear, and the residual amount of the salt-tolerant flocculant STZP in the solution can be determined;

FIG. 3 is a reversible transition diagram of the external pH change in examples 1-5 on the sol-gel process of the salt tolerant flocculant STZP in a one-component system, as shown in FIG. 3: the salt-tolerant flocculating agent STZP contains a large number of amphoteric groups (amino and carboxyl), so that the salt-tolerant flocculating agent STZP can be completely dissolved in a weak alkaline aqueous solution, and the sol-gel transformation of the solution is realized by adjusting the pH value; the sol-gel transition process triggered by NaOH and HCl can be repeated 5 times; under the action of carboxylic acid group protonation, the color of the salt-tolerant flocculant STZP is changed from colorless to milky in the gelation process by adjusting the pH;

FIG. 4(a) is a graph of the effect of ionic strength on the transmittance of salt-tolerant flocculant solutions of examples 1-5, as shown in FIG. 4 (a): when the pH value is 10, the light transmittance of the salt-tolerant flocculant STZP solution in the salt solution is basically unchanged and is kept above 95 percent as the NaCl concentration is increased from 150g/L to 250 g/L; when the salt concentration reaches 250g/L, the solution is saturated, and the light transmittance of the salt-tolerant flocculant STZP solution is slightly reduced due to the overhigh salt concentration; FIG. 4(b) is a graph of viscosity versus shear rate for 1g/L flocculant STZP at high NaCl concentrations as shown in FIG. 4(b) for examples 1-5: at 0.159s^-1At high shear rates of STZP solutionThe maximum viscosity of the salinity (155g/L) is 0.066 Pa.s, and the good thickening capability is shown, which is mainly due to the enhancement of the hydrophobic association degree among molecules and the enhancement of the thickening degree, which leads to the enhancement of the formation of a three-dimensional network; by salt incorporation, it is noted that the viscosity of the STZP solution is low even at high salt concentrations. This also demonstrates that STZP can be uniformly dispersed in solution in the presence of 155g/L NaCl and is not prone to aggregation; FIG. 4(c) is a graph showing the effect of ionic strength on the Zeta potential and residual level of flocculant for examples 1-5, as shown in FIG. 4 (c): when the pH value is 10, the Zeta potential of the salt-tolerant flocculant STZP solution is always a negative value within the NaCl concentration range of 150-250 g/L; when the salt concentration is 250g/L, the total retention rate of the salt-tolerant flocculating agent STZP in water exceeds 78.78%, and the good salt tolerance of the flocculating agent STZP is reflected. FIG. 4(d) is a graph showing the effect of ionic strength on the Zeta potential and residual amount of the dye in examples 1-5, as shown in FIG. 4 (d): when the NaCl concentration is higher than the critical concentration (155g/L), the dye reaches the isoelectric point, indicating that the negatively charged dye molecules are completely shielded by the counter ions, at which time the solubility of the dye in water is at a minimum. Therefore, based on the unique salt resistance of the flocculating agent STZP, the used salt-resistant flocculating agent can be recycled through a NaCl/water solution system;

FIG. 5(a) is a graph of the in situ decolorization behavior of the pH-induced fluid salt tolerant flocculant STZP of examples 1-5, as shown in FIG. 5 (a): the removal rate of the dye increases sharply with decreasing pH. When the pH decreased from 6 to 1, the dye removal increased from 11.8% to 96.8%; FIG. 4(b) is a graph showing the effect of concentration of salt tolerant flocculant STZP on dye decolorization in examples 1-5, as shown in FIG. 5 (b): at an initial dye concentration of 0.2g/L (pH 1), the dye decolorization efficiency is increased along with the increase of the dosage of the salt-tolerant flocculant STZP, and the dye removal rate is increased from 54.4% to 97.6% along with the increase of the dosage of the salt-tolerant flocculant STZP from 5mg/L to 100 mg/L; when the using amount is further increased, the removal rate gradually tends to be balanced and can reach 99.4 percent; FIG. 5(c) shows the effect of the salt-tolerant flocculant STZP on the dye decoloring performance at different NaCl concentrations in examples 1-5, and it can be seen from the figure that the salt has little effect on the dye decoloring rate, indicating that the STZP has excellent salt tolerance and can flocculate in a high-salt system;

FIG. 6(a) is a graph showing the release rate of the fluid salt tolerant flocculant STZP from the flocculated sludge at different pH values in examples 1-5, as shown in FIG. 6(a), the release efficiency gradually increases with increasing pH from 1.0 to 11.0, the flocculant can be completely released when the pH is more than or equal to 10.0, and the regenerated fluid salt tolerant flocculant STZP and the dye are mutually miscible to form a uniform solution; FIG. 6(b) is the retention rate of 1g/L salt-tolerant flocculant STZP and 2g/L dye in two components of the filter paper with medium speed of 30-50 μm under high concentration salt solution in examples 1-5, as shown in FIG. 6 (b): along with the increase of the NaCl concentration from 150g/L to 225g/L, the solute rejection rate of the filter paper is correspondingly increased, and the dye rejection rate is far greater than that of the salt-tolerant flocculant STZP; the retention rates of the separation membrane added with 155g/L NaCl on the dye and the salt-tolerant flocculant STZP are respectively 95.23% and 24.12%, so that the separation of the solid dye and the fluid salt-tolerant flocculant STZP can be realized by adding salt; fig. 6(c) is the effect of NaCl concentration on the separation performance of dye/flocculant STZP mixtures (pH 10) in examples 1-5; as shown in fig. 6 (c): with the increase of NaCl content, solute can be precipitated from the solution, so that flux is reduced, and the flux reduction speed of the dye is observed to be obviously higher than that of a salt-tolerant flocculant STZP; as the NaCl concentration increased from 150g/L to 225g/L, the separation factor increased from 13.52 to 50.40; under the high NaCl concentration (155g/L), the flux of the salt-tolerant flocculant STZP and the dye are respectively 0.088 kg-m^-2·h^-1And 0.011kg · m^-2·h^-1The separation coefficient is 15.99, which shows that the common filter paper can realize the effective separation of the fluid salt-tolerant flocculant STZP and the dye; FIG. 6(d) is the decolorization efficiency of the fluid salt tolerant flocculant STZP of examples 1-5 of the present invention for 5 consecutive adsorption/desorption cycles; as shown in fig. 6 (d): the used fluid salt-tolerant flocculant STZP can be regenerated and continuously reused for 5 times, the dye adsorption efficiency is slightly reduced (about 4.85 percent), and the fluid salt-tolerant flocculant STZP can be efficiently regenerated and recycled.

Example 6

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance, adjusting the pH to 0.2 by using a diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 1 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 1g of inorganic salt sodium chloride into 100mL of the 10-time concentrated mixed solution prepared in the step a, wherein the salt concentration is 10g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 30 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 5min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 7

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance at room temperature, adjusting the pH to 1 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 3 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 2.5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 25g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 10min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 8

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance at room temperature, adjusting the pH to 2 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 5 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 50g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 15-30min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 9

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance at room temperature, adjusting the pH to 6 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 7 with 1M HCl water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. mixing the concentrated 10 times prepared in step aAdding 7.5g inorganic salt sodium chloride with salt concentration of 75g/L into 100mL solution, magnetically stirring for 5min, filtering with common medium speed filter paper with radius of 3cm and pore diameter of 35 μm at normal pressure, and measuring effective area 0.001257-0.002827m through common medium speed filter paper within 20min by using 100mL measuring cylinder²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 10

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance at room temperature, adjusting the pH to 9 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 11 with 1M NaOH water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 10g of inorganic salt sodium chloride into 100mL of the 10-time concentrated mixed solution prepared in the step a, wherein the salt concentration is 100g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring by using a 100mL measuring cylinder through the common medium-speed filter paper within 25minEffective area 0.001257-0.002827m²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 11

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether into 1L of dye wastewater of 0.2g/L prepared in advance at room temperature, adjusting the pH to 9 by using diluted 1M HCl aqueous solution, magnetically stirring for 2min, and finishing flocculation after the decoloration of active brilliant red K-2BP is finished, the flocculated sludge was collected by filtration through a microporous membrane having a pore size of 0.45 μm and placed in a beaker containing 100mL of purified water, adjusting pH to 10 with 1M NaOH water solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein the mass ratio of the salt-tolerant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 12.5g of inorganic salt sodium chloride into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 125g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 30min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

The method of examples 6-11 was used to achieve a fluid salt tolerant flocculant, 2, 4-bis (p-aminobenzoate) - [1,3,5] with a low sodium chloride concentration of 10-125g/L]-triazine-6-starch ether (STZP) regeneration and recycling, tested for its separation and reuse properties see fig. 7-fig. 8; FIG. 7(a) is a graph showing the effect of low NaCl concentration on the transmittance of the fluid salt-tolerant flocculant STZP solution in examples 6-11 of the present invention, as shown in FIG. 7 (a): the light transmittance of the salt-tolerant flocculant STZP solution in the salt solution is basically unchanged and is kept above 96.6% along with the increase of the NaCl concentration from 10g/L to 125g/L, which indicates that the fluid flocculant STZP solution has good salt tolerance; FIG. 7(b) is a graph of viscosity versus shear rate for 1g/L flocculant STZP at low NaCl concentrations in examples 6-11 of the present invention, as shown in FIG. 7 (b): the apparent viscosity of the polymer drops sharply at low shear rates, exhibiting shear thinning behavior. Since the viscosity of the flocculant STZP solution is very low, the viscosity change tendency is mainly due to the high shear rate. The apparent viscosity of STZP increased with increasing NaCl concentration at 0.159s when the salt concentration increased from 50g/L to 100g/L^-1The maximum viscosity increased from 0.053 pas to 0.063 pas at shear rate. Therefore, the STZP solution shows good thickening ability at high salinity (100g/L), mainly due to the enhancement of the intermolecular hydrophobic association degree and the enhancement of the thickening degree resulting in the enhancement of the formation of a three-dimensional network; by salt incorporation, it is noted that even at high salt concentrations, the viscosity of the STZP solution is low; FIG. 7(c) is a graph showing the effect of low NaCl concentration on the Zeta potential and residual amount of the fluid salt-tolerant flocculant STZP in examples 6-11 of the present invention, as shown in FIG. 7 (c): when the pH value is 10, measuring the Zeta potential of the fluid salt-resistant flocculant STZP solution in the NaCl concentration range of 10-125 g/L; colloidThe Zeta potential of the particles is always negative in the measured salinity range and shows an ascending trend at high salt concentrations; when the NaCl concentration reaches 125g/L, the total retention rate of the fluid salt-resistant flocculant STZP exceeds 87.55%, which shows that the fluid flocculant STZP has excellent salt resistance; FIG. 7(d) is a graph showing the Zeta potential and the residual amount of active bright red K-2BP at a low NaCl concentration in examples 6-11 of the present invention, as shown in FIG. 7 (d): in the case of low salt, the Zeta potential of the reactive brilliant red K-2BP solution is systematically negative due to the ionization of the sulfonic acid groups; the addition of inorganic salt (NaCl) can cause the Zeta potential of the active brilliant red K-2BP solution to be remarkably increased, and a large amount of active brilliant red K-2BP is coagulated and separated out; when 125g/L NaCl was added, the residual amount of reactive brilliant red K-2BP decreased to 11.87%, indicating that reactive brilliant red K-2BP could be separated from water by salting out;

FIG. 8(a) is a graph showing the retention rate of a two-component 1g/L salt-tolerant flocculant STZP and a 2g/L dye on a common medium-speed filter paper having a pore size of 30 to 50 μm in examples 6 to 11 of the present invention in a NaCl concentration range of 10 to 125g/L, as shown in FIG. 8 (a): along with the increase of the NaCl concentration from 10g/L to 125g/L, the solute rejection rate of the separation membrane is correspondingly increased, but the dye rejection rate is far greater than that of the salt-tolerant flocculant STZP; adding 125g/L NaCl into the mixed solution of the dye and the salt-tolerant flocculant STZP, wherein the retention rates of the filter paper on the dye and the salt-tolerant flocculant STZP are respectively 90.53% and 15.19%, which shows that the separation of the fluid salt-tolerant flocculant STZP and the solid dye K-2BP can be realized through the filter paper; fig. 8(b) is a graph of the separability of dye/flocculant mixtures at pH 10 in the NaCl concentration range of 10-125g/L in examples 6-11 of the present invention, as shown in fig. 8 (b): under the condition of 10g/LNaCl, the permeation flux of the dye and the salt-tolerant flocculant STZP is larger and is respectively 0.683 kg.m^-2·h^-1And 0.346kg m^-2·h^-1(ii) a But the selectivity of the salt-tolerant flocculant STZP in the filtrate is poor, and the separation factor is only 1.013; as NaCl content increases, solute precipitates out of solution, resulting in flux reduction, but the rate of flux reduction of dye is significantly higher than that of salt tolerant flocculant STZP, which is a salt tolerant flocculant with high solubility in salt solution because the dye undergoes salting out precipitation in brine and is thus trapped by filter paper,thus, may penetrate the filter paper to form a fluid flocculant; the separation factor is increased from 1.013 to 8.562 along with the increase of the NaCl concentration from 10g/L to 125g/L, which shows that the filter paper has good separation effect on the fluid salt-tolerant flocculant STZP and the solid dye K-2 BP;

under the condition of keeping other reaction conditions unchanged, the fluid salt-resistant flocculant STZP is adopted to execute the steps a-c again, the regeneration and recycling performance of the fluid salt-resistant flocculant STZP is tested, 84.81% of the fluid salt-resistant flocculant STZP can be recovered in 125g/L of NaCl solution, and the dye decolorization rate can still reach 88.6% when the recovered and reused fluid salt-resistant flocculant STZP is put into a new round of dye decolorization experiment.

Example 12

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 0.2, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 1g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 10g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 30 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 5min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. taking 0.5mL of the fluid salt-tolerant flocculant obtained in the step b, diluting by 100 times, calculating the concentration of the salt-tolerant flocculant in the filtrate by an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater in a mass ratio of 1:2, and using diluted 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 2min, and performing flocculating precipitation on the active brilliant red K-2BP to realize the recycling of the regenerated fluid salt-resistant flocculant.

Example 13

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 1, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 3, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 2.5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 25g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 10min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. taking 0.5mL of the fluid salt-resistant flocculant obtained in the step b, and diluting by 100 timesCalculating the concentration of the salt-tolerant flocculant in the filtrate by an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater in a mass ratio of 1:2, and diluting with 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 2min, and performing flocculating precipitation on the active brilliant red K-2BP to realize the recycling of the regenerated fluid salt-resistant flocculant.

Example 14

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 2, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 5, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 50g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 15min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. taking 0.5mL of the fluid salt-tolerant flocculant obtained in the step b, diluting by 100 times, calculating the concentration of the salt-tolerant flocculant in the filtrate by using an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater according to the mass ratio of 1:2, and usingDiluted 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 2min, and performing flocculating precipitation on the active brilliant red K-2BP to realize the recycling of the regenerated fluid salt-resistant flocculant.

Example 15

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 6, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 7, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 7.5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 7.5g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 35 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 20min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

c. taking 0.5mL of the fluid salt-tolerant flocculant obtained in the step b, diluting by 100 times, calculating the concentration of the salt-tolerant flocculant in the filtrate by an ultraviolet spectrophotometer, blending the regenerated fluid salt-tolerant flocculant and the dye wastewater in a mass ratio of 1:2, and using diluted 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 2min, and performing activated bright red K-2BP flocculation precipitation to realize salt tolerance of the regenerated fluidAnd (5) recycling the flocculating agent.

Example 16

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting the pH value of the aqueous solution to 9, magnetically stirring for 2min, after the completion of decolorization of the active brilliant red K-2BP, finishing flocculation, filtering and collecting flocculated sludge through a microporous filter membrane with the pore diameter of 0.45 mu M, placing the flocculated sludge in a beaker containing 100mL of purified water, adjusting the pH value to 11 by using an aqueous solution of 1M NaOH, and magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) - [1,3,5] flocculant]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 10g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 100g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 25min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 17

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting the pH value of the aqueous solution to 9, magnetically stirring for 2min, after the completion of decolorization of the active brilliant red K-2BP, finishing flocculation, filtering and collecting flocculated sludge through a microporous filter membrane with the pore diameter of 0.45 mu M, placing the flocculated sludge in a beaker containing 100mL of purified water, adjusting the pH value to 10 by using an aqueous solution of 1M NaOH, and magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) - [1,3,5] flocculant]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 12.5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is prepared in the step a and is concentrated by 10 times, wherein the salt concentration is 125g/L, magnetically stirring for 5min, filtering at normal pressure by using a common medium-speed filter paper with the radius of 3cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 30min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 18

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starchPowdered ether, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 0.2, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 1, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 15g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 150g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 30 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 5min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 19

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 1, magnetically stirring for 2min, and introducing until the active brilliant red K-2BP decolorization is completed and flocculation is finishedFiltering the flocculated sludge through a microporous membrane with a pore size of 0.45 μm, collecting the flocculated sludge, placing the flocculated sludge in a beaker containing 100mL of purified water, and then using 1M H₂SO₄Adjusting the pH value of the aqueous solution to 3, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 17.5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 175g/L, magnetically stirring for 5min, filtering at normal pressure by using a common medium-speed filter paper with the radius of 3cm and the pore diameter of 40 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 10min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 20

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. adding 20g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 200g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 2cm and the pore diameter of 50 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 15min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

Example 21

a. at room temperature, adding a fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of dye wastewater of 0.2g/L prepared in advance]-triazine-6-starch ethers, diluted 1M H₂SO₄Adjusting pH of the aqueous solution to 6, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μm to collect flocculated sludge after the completion of decolorization of active brilliant red K-2BP, placing the flocculated sludge in a beaker containing 100mL of purified water, and adding 1M H₂SO₄Adjusting the pH value of the aqueous solution to 7, magnetically stirring for 30min to obtain a 10-time concentrated mixed solution, wherein the salt-tolerant flocculant is 2, 4-bis (p-aminobenzoic acid) -1, 3,5]-threeThe mass ratio of the oxazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

b. b, adding 22.5g of inorganic salt sodium sulfate into 100mL of the mixed solution which is concentrated by 10 times and is prepared in the step a, wherein the salt concentration is 225g/L, magnetically stirring for 5min, filtering at normal pressure by using common medium-speed filter paper with the radius of 3cm and the pore diameter of 35 mu m, and measuring the effective area 0.001257-0.002827m of the common medium-speed filter paper by using a 100mL measuring cylinder within 20min²Collecting the filtrate and filter cake to obtain renewable fluid salt-tolerant flocculant and salting-out solid active bright red K-2 BP;

recycling the fluid salt-resistant flocculant:

The method of examples 12-21 was used on inorganic salts Na₂SO₄The concentration is 10-225g/L, the regeneration and the recycling of the fluid salt-tolerant flocculant STZP are realized, and the regeneration performance is shown in figure 9 through tests; FIG. 9(a) shows Na in examples 12 to 21 of the present invention₂SO₄Influence of concentration on the light transmittance of the fluid salt-tolerant flocculant STZP solution; as shown in fig. 9 (a): with Na₂SO₄The concentration is increased from 10g/L to 225g/L, the light transmittance of the salt-tolerant flocculant STZP solution in the salt solution is slowly reduced, and Na is added under the same salt concentration₂SO₄The light transmittance of the salt-tolerant flocculant STZP is lower than that of NaCl, which shows that the solubility of the salt-tolerant flocculant STZP in a salt solution not only depends on the ionic strength, but also depends on the ion species; FIG. 9(b) shows the difference in Na in examples 12 to 21 of the present invention₂SO₄Under the concentration, the influence of a fluid salt-tolerant flocculating agent STZP on the decoloring performance of the active brilliant red K-2 BP; as shown in fig. 9 (b): in the dye wastewater, Na is accompanied₂SO₄The concentration is increased from 0 to 20g/L, and the removal rate of reactive brilliant red K-2BP is reduced by 6.4 percent; when Na is present₂SO₄When the concentration is 100g/L, the dye removal rate is improved by 1.6 percent compared with a salt-free system, and the salt resistance is excellent;

under the condition of keeping other reaction conditions unchanged, high-concentration Na is adopted₂SO₄Step a-c is carried out again, the fluid salt-tolerant flocculant is 2, 4-di (p-aminobenzoic acid radical) - [1,3,5]]-regeneration and recycling properties of triazine-6-starch ether (STZP), see table 1;

table 1: 155g/L of Na₂SO₄Recycling property of fluid salt-tolerant flocculant STZP

Na at 155g/L₂SO₄In the solution, the retention rate of the filter paper on the active brilliant red K-2BP is up to 96.5 percent, and the salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] is added]-triazine-6-starch ether (STZP) rejection of 28.4%, i.e. 71.6%, of fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3, 5%]-triazine-6-starch ether (STZP) can be recovered; and is noteworthy that the recycled fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5]]When the triazine-6-starch ether (STZP) is put into a new round of reactive brilliant red K-2BP decolorization experiment, the decolorization rate of the reactive brilliant red K-2BP can still reach 93.1 percent.

Example 22 (control)

Under the condition of no salt, the regeneration performance of the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] -triazine-6-starch ether (STZP) is added:

a. adding a fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) into 1L of printing and dyeing wastewater, wherein the mass ratio of the salt-tolerant flocculant to active brilliant red K-2BP in the printing and dyeing wastewater is 1:2, adjusting the pH to 1 by using a diluted 1M HCl aqueous solution, magnetically stirring for 2min, filtering and collecting flocculated sludge through a microporous filter membrane with the pore diameter of 0.45 mu M after decoloration of the active brilliant red K-2BP is completed, putting 0.3g of the flocculated sludge into a beaker containing 100mL of purified water, adjusting the pH of the solution to 10-12 by using a 1M NaOH aqueous solution, and magnetically stirring for 30min to realize desorption of the active brilliant red K-2BP and complete release of the salt-tolerant flocculant STZP to obtain a mixed solution concentrated by 10 times;

b. b, magnetically stirring the mixed solution concentrated by 10 times obtained in the step a for 5min, directly filtering the mixed solution at normal pressure by using common medium-speed filter paper with the radius of 2-3cm and the pore diameter of 30-50 mu m, measuring the volume of filtrate passing through the common medium-speed filter paper with the effective area by using a 100mL measuring cylinder within 5min, and collecting the filtrate and filter cakes to obtain a renewable fluid salt-resistant flocculant and salted-out solid active bright red K-2 BP;

recycling the fluid salt-tolerant flocculant STZP:

c. taking 0.5mL of the fluid salt-tolerant flocculant STZP obtained in the step b, diluting by 100 times, calculating the concentration of the salt-tolerant flocculant STZP in the filtrate by using an ultraviolet spectrophotometer, and evaluating the separation performance of the fluid salt-tolerant flocculant and the salting-out solid active bright red K-2 BP;

the regeneration performance of the fluid salt tolerant flocculant STZP was achieved as a blank control using the method of example 22 and its separation and reuse performance as shown in FIG. 10 by testing; FIG. 10 shows the salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] for a 1g/L fluid under salt-free conditions in example 22 of the present invention]-viscosity versus shear rate of triazine-6-starch ether (STZP); as shown in fig. 10: the apparent viscosity of the polymer drops sharply at low shear rates, exhibiting shear thinning behavior; at 0.159s ^-12, 4-bis (p-aminobenzoate) - [1,3,5] flocculant]-triazine-6-starch ether (STZP) has a maximum viscosity of 0.041Pa · s. 2, 4-di (p-aminobenzoic acid) -1, 3,5]The viscosity of the triazine-6-starch ether (STZP) solution is very low, the viscosity trend mainly coming from high shear rates;

under the condition of keeping other reaction conditions unchanged, under the salt-free condition, testing the separation performance of the fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] -triazine-6-starch ether (STZP) and active bright red K-2BP to evaluate the regeneration performance of the fluid salt-tolerant flocculant STZP, which is shown in Table 2;

table 2: under the condition of no salt, the recovery and reutilization performance of fluid salt-tolerant flocculant STZP

In salt-free solution, filter paper is resistant to salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5]]-triazine-6-starch ether (STZP) rejection of 0.91%, i.e. 99.09%, of fluid salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3, 5%]Triazine-6-starch ether (STZP) was obtained, but only 1.74% of reactive brilliant red K-2BP was trapped in the filter paper, and a large amount of reactive brilliant red K-2BP still remained in the mixed solution contaminating the salt tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] with the salt tolerant flocculant]Triazine-6-starch ether (STZP), active brilliant red K-2BP and salt-tolerant flocculant 2, 4-bis (p-aminobenzoate) - [1,3,5] were not achieved]-isolation of triazine-6-starch ether (STZP); notably, the fluid salt-tolerant flocculant is 2, 4-bis (p-aminobenzoate) - [1,3, 5-]The permeation flux of the (S) -triazine-6-starch ether (STZP) was 0.350 kg. m^-2·h^-1While the reactive brilliant red K-2BP has higher penetration flux of 0.694kg · m^-2·h^-1At the moment, salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5 is added into the filtrate]The selectivity of the triazine-6-starch ether (STZP) is poor, the separation factor is only 1.009, and the fluid salt-resistant flocculant 2, 4-di (p-aminobenzoic acid radical) - [1,3,5] is difficult to realize]Separation of-triazine-6-starch ether (STZP) and reactive brilliant red K-2BP, i.e. unable to recycle salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5]-triazine-6-starch ether (STZP).

According to the blank control, a water-salt system can be an effective means for effectively separating the solid dye and the fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether (STZP), and the recovery and the recycling of the solid dye and the fluid salt-resistant flocculant 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-triazine-6-starch ether (STZP) are realized.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims

1. A method for regenerating and recycling a fluid salt-tolerant flocculating agent is characterized by comprising the following steps:

a. adding fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid group) - [1,3,5] into 1L of printing and dyeing wastewater]-triazine-6-starch ethers, diluted 1M H₂SO₄Or adjusting pH to 0.2-9 with 1M HCl aqueous solution, magnetically stirring for 2min, filtering with microporous membrane with pore diameter of 0.45 μ M to collect flocculated sludge after decolorizing active brilliant red K-2BP in printing and dyeing wastewater is completed, placing flocculated sludge in beaker containing 100mL purified water, adjusting pH to 1-11 with 1M NaOH or 1M HCl aqueous solution, magnetically stirring for 30min to obtain 10 times concentrated mixed solution, wherein salt-tolerant flocculant is 2, 4-bis (p-aminobenzoate) - [1,3,5]]The mass ratio of the-triazine-6-starch ether to the reactive brilliant red K-2BP in the printing and dyeing wastewater is 1: 2;

the water salt system separates solid dye and fluid salt-tolerant flocculant:

recycling the fluid salt-resistant flocculant:

c. c, taking the fluid salt-resistant flocculant obtained in the step b, namely 2, 4-di (p-aminobenzoic acid radical) - [1,3, 5-]0.5mL of-triazine-6-starch ether, diluting by 100 times, and calculating a salt-resistant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5 in the filtrate by using an ultraviolet spectrophotometer]-concentration of triazine-6-starch ether, flocculating agent 2, 4-bis (p-aminobenzoic acid) -1, 3, 5-bis (p-aminobenzoic acid) with salt tolerance of the regenerated fluid]Mixing (by mass ratio) triazine-6-starch ether with reactive brilliant red K-2BP in printing and dyeing wastewater at 1:2, and diluting with 1M H₂SO₄Or adjusting the pH value of 1M HCl aqueous solution to 1, magnetically stirring for 2min, and performing active bright red K-2BP flocculation precipitation to realize the regeneration fluid salt-tolerant flocculant 2, 4-di (p-aminobenzoic acid) -1, 3,5]Recycling of the triazine-6-starch ether.