An environmentally friendly wastewater high-efficiency decolorizing flocculant and its preparation method

Abstract

The present invention relates to the field of printing and dyeing wastewater treatment, and specifically discloses an environmentally friendly wastewater high-efficiency decolorization flocculant and a preparation method thereof. The preparation method of the environmentally friendly wastewater high-efficiency decolorization flocculant comprises the following steps: step 1, preparing a dicyandiamide formaldehyde decolorization agent; step 2, preparing modified zeolite particles; step 3, preparing an environmentally friendly wastewater high-efficiency decolorization flocculant. The flocculant prepared above has the advantages of being conducive to better improving the decolorization and flocculation effect of the flocculant while also preventing the ammonia nitrogen content in the treated wastewater from increasing easily.

Description

Technical Field

[0001] The invention relates to the field of printing and dyeing wastewater treatment, and in particular to an environmentally friendly wastewater high-efficiency decolorizing flocculant and a preparation method thereof. Background Art

[0002] Dicyandiamide formaldehyde polycondensate is a new type of high-efficiency decolorant that came out in the 1990s. It has the special effect of removing the color of dye wastewater. By providing a large number of cations, the negative charges on the dye molecules are neutralized and destabilized. At the same time, the added high-efficiency decolorizing flocculant generates a large amount of flocs due to hydrolysis, which can adsorb and capture the destabilized dye molecules, separate them from the water body, and achieve the purpose of decolorization. Therefore, dicyandiamide formaldehyde decolorizer has become the most widely used substance in many methods of printing and dyeing wastewater treatment.

[0003] The preparation of traditional dicyandiamide formaldehyde decolorizing flocculant is generally synthesized by using dicyandiamide and formaldehyde under the catalytic action of hydrochloric acid or other types of inorganic acids, but the dicyandiamide formaldehyde decolorizing flocculant synthesized by the traditional process has strong hydrophobicity, low polymerization degree, weak adsorption capacity, and is often not easy to disperse in wastewater containing surfactants, resulting in poor flocculation effect. Therefore, the currently commonly used improved preparation method is usually to use dicyandiamide and formaldehyde as raw materials, add ammonium chloride as a catalyst, so that the molecular chain obtained by polycondensation contains amino groups, imino groups and the like, which is conducive to better combining with the azo structure and sulfonic acid groups contained in the wastewater dye molecules, so that the flocculant has a better decolorization effect; at the same time, the amino group and the imino group are hydrophilic groups, which is conducive to better improving the hydrophilicity of the decolorizing flocculant, and is conducive to the decolorizing flocculant being more easily dispersed in the wastewater, thereby better achieving the decolorization and flocculation effect.

[0004] However, although the introduction of amino and imino groups into the decolorizing flocculant can improve the decolorizing and flocculating effect of the decolorizing flocculant to a certain extent, the introduced groups also contain ammonia nitrogen, which makes it easy for the wastewater after decolorizing and flocculating treatment to have excessive ammonia nitrogen content and difficult to meet the discharge standards. Therefore, there is still room for improvement. Summary of the invention

[0005] In order to better reduce the ammonia nitrogen content of wastewater after flocculation treatment, the present application provides an environmentally friendly wastewater high-efficiency decolorization flocculant and a preparation method thereof.

[0006] In the first aspect, the present application provides a method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, which adopts the following technical solution:

[0007] A method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant comprises the following steps:

[0008] Step 1, preparing dicyandiamide formaldehyde decolorizing agent, is as follows:

[0009] Step 1-1, by weight, add 80-85 parts by weight of dicyandiamide, 60-65 parts by weight of formaldehyde and 16-19 parts by weight of ammonium chloride into a reaction kettle, raise the temperature to 70-80° C., adjust the pH to 7-8, and react at a constant temperature for 100-130 minutes to obtain a preliminary mixture;

[0010] Step 1-2, continue to add 34-36 parts by weight of ammonium chloride to the preliminary mixture, increase the temperature to 70-80° C., adjust the pH to 4-5, and react at a constant temperature for 60-120 minutes to obtain a polymer;

[0011] Step 1-3, discharging the material at a constant temperature, and placing the discharged polymer in an open container and standing until the temperature of the polymer drops to room temperature to form a viscous liquid, thereby obtaining a dicyandiamide formaldehyde decolorizer;

[0012] Step 2, preparing modified zeolite particles, is as follows:

[0013] The zeolite is ground into powder, carboxymethyl cellulose glue is added to the powdered zeolite, and the mixture is stirred to form a paste, and the mixture is re-granulated to form zeolite particles, and then a layer of polyvinyl alcohol glue is coated on the surface of the zeolite particles, and the mixture is dried to obtain modified zeolite particles.

[0014] Step 3, preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, as follows:

[0015] By weight, 75-80 parts by weight of the dicyandiamide formaldehyde decolorizer prepared in step 1, 15-20 parts by weight of the coagulant aid and 5-10 parts by weight of the modified zeolite particles prepared in step 2 are mixed and stirred to disperse evenly, thereby obtaining an environmentally friendly wastewater high-efficiency decolorization flocculant.

[0016] By using ammonium chloride as a raw material for preparing a dicyandiamide formaldehyde decolorizer to replace hydrochloric acid in the traditional process, the dicyandiamide formaldehyde molecular chain obtained by the reaction contains more amino and imino groups, which is conducive to better combining with the azo structure and sulfonate groups contained in the wastewater dye molecules, so that the decolorization effect of the flocculant is better; at the same time, the amino and imino groups are both hydrophilic groups, which is conducive to better and more uniform dispersion of the flocculant in the wastewater, so that the decolorization and flocculation effects of the flocculant are better and more efficient.

[0017] At the same time, the catalyst ammonium chloride used in the reaction, the coagulant aid used in combination with the decolorizer, and the modified zeolite are not likely to cause environmental pollution, making the flocculant more environmentally friendly.

[0018] Since carboxymethyl cellulose glue is a substance that can be quickly dissolved in water, when the above-mentioned flocculant is put into wastewater for use, the dicyandiamide formaldehyde decolorizing agent and the coagulant aid will gradually dissolve, adsorb and flocculate the dye molecules and suspended matter and other impurities in the water, while the modified zeolite particles are temporarily insoluble in water under the protection of polyvinyl alcohol, so that the zeolite is not easy to affect the decolorization effect of the amino group and the imino group on the dicyandiamide formaldehyde decolorizing agent; when the impurities such as color and suspended matter in the wastewater are removed to a certain extent, the polyvinyl alcohol will also gradually and slowly dissolve in the water, so that the coated zeolite is released. If the solubility of polyvinyl alcohol is insufficient, the wastewater purified by the preliminary flocculant can be heated to make the temperature of the wastewater rise to 55-60°C, so as to accelerate the dissolution of polyvinyl alcohol, so that the coated zeolite is completely released, which is conducive to better absorption. The ammonia nitrogen in the attached wastewater makes it difficult for the ammonia nitrogen content in the wastewater to reach the discharge standard due to the addition of flocculants, thereby making the decolorization and flocculation effect of the flocculant better; at the same time, polyvinyl alcohol contains a large number of hydrophilic groups, which is conducive to the modified zeolite particles to be better and more evenly dispersed in the wastewater and better play the role of adsorbing ammonia nitrogen; in addition, since the modified zeolite particles are made of powder pressed granules, polyvinyl alcohol glue is also a water-soluble substance, and the difference in the dissolution time of carboxymethyl cellulose glue and polyvinyl alcohol glue in water is utilized, the modified zeolite particles are easy to become loose after being soaked in water for a certain period of time, so that the modified zeolite particles will gradually disperse into powder in the wastewater, float in the water, and be adsorbed by the flocculant, thereby making the subsequent cleaning of the wastewater flocculation simpler and more convenient, and the flocculation precipitation only needs to be discharged as sludge.

[0019] By adopting the above technical scheme, it is beneficial to better improve the decolorization and flocculation effects of the flocculant, making the decolorization and flocculation of the flocculant more efficient; at the same time, it makes the wastewater less likely to be affected by the decolorization flocculant and cause the ammonia nitrogen content to fail to meet the standard; in addition, it makes the subsequent cleaning of the modified zeolite particles simpler and more convenient, and makes the modified zeolite particles less likely to affect the adsorption of the flocculant before the flocculant takes effect.

[0020] Preferably, the reaction temperature in step 1-1 is 70-75°C, the pH value is 7.5-7.6, and the reaction time is 115-120 min; the reaction temperature in step 1-2 is 70-75°C, the pH value is 4.8-5.0, and the reaction time is 110-120 min.

[0021] By controlling the reaction conditions in step 1-1 and step 1-2, the performance of the dicyandiamide formaldehyde decolorizer obtained by polymerization can be improved, so that dicyandiamide has better water solubility, more moderate molecular weight, and is easier to form a viscous liquid, which is conducive to more uniform dispersion of modified zeolite particles in the polymer, and further helps to better improve the decolorization effect of the flocculant.

[0022] Preferably, in step 1-1, a catalyst is also added, and the catalyst is any one of sodium hydroxide, calcium hydroxide, potassium hydroxide, and sodium acetate.

[0023] More preferably, the catalyst is sodium hydroxide.

[0024] By adding a Lewis base as a catalyst in step 1-1, and preferably sodium hydroxide as a catalyst, it is beneficial to better shorten the curing time of the dicyandiamide formaldehyde decolorizer, so that the preparation of the dicyandiamide formaldehyde decolorizer is more efficient.

[0025] Preferably, in step 2, after the surface of the modified zeolite particles is coated with polyvinyl alcohol glue, a water-soluble film is adhered to the surface of the polyvinyl alcohol glue, and the temperature at which the water-soluble film dissolves in water is 40-45°C.

[0026] By adhering a layer of water-soluble film on the outer surface of the modified zeolite particles, it is beneficial to better wrap the modified zeolite particles, so that when the dicyandiamide formaldehyde decolorizer is dissolved in water and plays a decolorizing role, the modified zeolite particles are less likely to be exposed to water, which may affect the decolorization effect of the dicyandiamide formaldehyde decolorizer. The exposure time of the modified zeolite particles can be instantly controlled by controlling the water temperature according to the actual decolorization flocculation situation.

[0027] Preferably, in step 2, the particle size of the powdered zeolite powder is 0.5-1 μm.

[0028] By controlling the particle size of the powdered zeolite powder, it is helpful to better control the time for the modified zeolite particles to disperse into powder in water, so that the modified zeolite particles can better fully play the role of adsorbing ammonia nitrogen, and it is helpful to reduce the situation where the modified zeolite particles are dispersed into powder and adsorbed by flocculants before the ammonia nitrogen in the wastewater is fully adsorbed; at the same time, the zeolite powder after complete dissolution and dispersion is more easily adsorbed by the flocculant, making the subsequent treatment of the zeolite powder more convenient and quicker.

[0029] Preferably, in step 2, the particle size of the zeolite particles formed by re-granulation is 20-30 μm.

[0030] By controlling the particle size of the modified zeolite particles, the modified zeolite particles can be more evenly dispersed in the dicyandiamide formaldehyde decolorizer, and are not easy to form precipitation and settle at the bottom of the decolorizer; at the same time, it is also beneficial to better control the time for the modified zeolite particles to disperse into powder in water, so that the modified zeolite particles can better fully play the role of adsorbing ammonia nitrogen, which is beneficial to reduce the situation where the modified zeolite particles are dispersed into powder and adsorbed by the flocculant before the ammonia nitrogen in the wastewater is fully adsorbed.

[0031] Preferably, in the steps 1-3, the viscosity of the dicyandiamide formaldehyde decolorizing agent is 50-80 Pa·s.

[0032] By controlling the consistency of the powdered dicyandiamide formaldehyde decolorizer, the modified zeolite particles can be better dispersed in the decolorizer, so that the modified zeolite particles are not easy to precipitate and are not easy to be dispersed evenly due to the excessive viscosity of the decolorizer, which is conducive to the flocculant to play a better role.

[0033] Preferably, the coagulant aid is polyacrylamide emulsion.

[0034] By selecting polyacrylamide emulsion as a coagulant aid, it is helpful to better accelerate the dissolution rate of the flocculant, so that the flocculant can take effect more quickly after being added to the water. At the same time, it also makes the charge stability of the flocculant higher and the flocculation effect better.

[0035] In the second aspect, the present application provides an environmentally friendly wastewater high-efficiency decolorizing flocculant, which adopts the following technical solution:

[0036] An environmentally friendly wastewater high-efficiency decolorizing flocculant is prepared by adopting the preparation method of the environmentally friendly wastewater high-efficiency decolorizing flocculant.

[0037] The flocculant prepared by the above preparation method can ensure efficient decolorization and flocculation of wastewater, and is not easy to introduce too much ammonia nitrogen to cause excessive ammonia nitrogen content in the wastewater, and the operation of decolorization and flocculation is simple and convenient.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. By adding modified zeolite particles and coagulant to the decolorizer, it is helpful to better improve the decolorization and flocculation effect of the flocculant, making the decolorization and flocculation of the flocculant more efficient, and it is not easy for the wastewater to be affected by the decolorization flocculant and cause the ammonia nitrogen content to fail to meet the standard, and it also makes the subsequent cleaning of the modified zeolite particles simpler and more convenient.

[0040] 2. By using polyvinyl alcohol to coat zeolite particles to form modified zeolite particles, the modified zeolite particles are less likely to affect the adsorption and decolorization of the flocculant before the flocculant takes effect, making the timing of the modified zeolite particles taking effect more appropriate.

[0041] 3. By controlling the particle size of zeolite powder, modified zeolite particles and the viscosity of dicyandiamide formaldehyde decolorizer, it is beneficial for the modified zeolite to be better dispersed in the decolorizer. At the same time, it is also beneficial to better control the dissolution time of the modified zeolite particles, and to better coordinate the decolorizer, coagulant and modified zeolite particles with each other, so that the timing of the modified zeolite particles to play a role is easier to control.

[0042] 4. The flocculant prepared by the above preparation method can ensure efficient decolorization and flocculation of wastewater, and is not easy to introduce too much ammonia nitrogen to cause excessive ammonia nitrogen content in the wastewater, and the operation of decolorization and flocculation is simple and convenient. DETAILED DESCRIPTION

[0043] The present application is further described in detail below with reference to embodiments and comparative examples.

[0044] In the following examples and comparative examples, the raw materials are all commercially available.

[0045] Example 1

[0046] The present application discloses a method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, comprising the following steps:

[0047] Step 1, preparing dicyandiamide formaldehyde decolorizing agent, is as follows:

[0048] Step 1-1, add 800g of dicyandiamide, 600g of formaldehyde and 160g of ammonium chloride into a 2000mL three-necked flask equipped with a magnetic stirrer, a thermometer and a reflux condenser, and add potassium hydroxide, adjust the pH to 7.0, then increase the temperature to 80°C, and react at a constant temperature for 100min to obtain a preliminary mixture.

[0049] Step 1-2, continue to slowly add 340g of solid ammonium chloride to the preliminary mixture, add it over 30 minutes, and keep the temperature of the system at 80°C, add hydrochloric acid to adjust the pH to 4.0, and react at a constant temperature for 60 minutes to obtain a polymer.

[0050] Step 1-3, discharging the material at a constant temperature, and placing the discharged polymer in an open beaker, leaving it to stand under natural conditions, and naturally cooling it to room temperature, until the viscosity of the polymer detected is 30-40 Pa·s, thereby obtaining a dicyandiamide formaldehyde decolorizing agent.

[0051] Step 2, preparing modified zeolite particles, is as follows:

[0052] The zeolite is added into a mortar and ground into powder, and the powder with a particle size less than 0.5 μm is screened out, and the powder with a particle size greater than 0.5 μm is poured back into the mortar and ground again until the particle size of all the powders is less than 0.5 μm, and then 120 g of the zeolite powder with a particle size less than 0.5 μm is mixed evenly with 40 g of sodium carboxymethyl cellulose glue to form a paste, and then the paste is added into a granulator for granulation, and the particle size of the particles obtained by granulation is controlled to be 10-20 μm, and finally a layer of polyvinyl alcohol glue is coated on the surface of the zeolite particles, and dried to obtain modified zeolite particles.

[0053] Step 3, preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, as follows:

[0054] Take 750g of the dicyandiamide formaldehyde decolorizer prepared in step 1, 150g of the coagulant aid and 50g of the modified zeolite particles prepared in step 2, mix them evenly, and stir them so that the modified zeolite particles are evenly dispersed in the dicyandiamide formaldehyde decolorizer to obtain an environmentally friendly wastewater high-efficiency decolorization flocculant.

[0055] In this embodiment, the coagulant aid is polyacrylamide emulsion.

[0056] Example 2

[0057] The difference from Example 1 is:

[0058] The specific operations of step 1 are as follows:

[0059] Step 1-1, add 850g of dicyandiamide, 650g of formaldehyde and 190g of ammonium chloride to a 2000mL three-necked flask equipped with a magnetic stirrer, a thermometer and a reflux condenser, and add calcium hydroxide, adjust the pH to 8.0, then increase the temperature to 76°C, and react at a constant temperature for 130min to obtain a preliminary mixture.

[0060] Step 1-2, continue to slowly add 360g of solid ammonium chloride to the preliminary mixture, add it over 30 minutes, and keep the temperature of the system at 76°C, add hydrochloric acid to adjust the pH to 4.5, and react at a constant temperature for 100 minutes to obtain a polymer.

[0061] Step 1-3, the polymer is allowed to stand and cool until the viscosity of the polymer detected is 90-100 Pa·s, thereby obtaining a dicyandiamide formaldehyde decolorizing agent.

[0062] In step 2, zeolite powder with a particle size of 1-2 μm is screened for granulation, and the particle size of the particles obtained by granulating the zeolite powder is controlled to be 40-50 μm.

[0063] The dosage of each component used in step 3 is different, as follows:

[0064] 800g decolorizer; 200g coagulant; 100g modified zeolite particles.

[0065] Example 3

[0066] The difference from Example 1 is:

[0067] The reaction temperature in step 1-1 is 70° C., the pH value is 7.5, and the reaction time is 120 min.

[0068] The reaction temperature in step 1-2 is 70° C., the pH value is 4.8, and the reaction time is 120 min.

[0069] The curing time in steps 1-3 is 16 hours.

[0070] Example 4

[0071] The difference from Example 1 is:

[0072] The reaction temperature in step 1-1 is 75° C., the pH value is 7.6, and the reaction time is 115 min.

[0073] The reaction temperature in step 1-2 is 75° C., the pH value is 5.0, and the reaction time is 110 min.

[0074] The curing time in steps 1-3 is 15 h.

[0075] Example 5

[0076] The difference from Example 1 is that in step 2, after a layer of polyvinyl alcohol glue is coated on the surface of the zeolite particles, a layer of water-soluble film is adhered to the outside of the polyvinyl alcohol glue, and the dissolution temperature of the water-soluble film in water is 40-45°C.

[0077] Example 6

[0078] The difference from Example 1 is:

[0079] Step 1-3, the polymer is allowed to stand and cool until the viscosity of the polymer detected is 50-80 Pa·s, thereby obtaining a dicyandiamide formaldehyde decolorizing agent.

[0080] In step 2, zeolite powder with a particle size of 0.5-1 μm is screened for granulation, and the particle size of the particles obtained by granulating the zeolite powder is controlled to be 20-30 μm.

[0081] Example 7

[0082] The present application discloses a method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, comprising the following steps:

[0083] Step 1, preparing dicyandiamide formaldehyde decolorizing agent, is as follows:

[0084] Step 1-1, add 820g of dicyandiamide, 630g of formaldehyde and 180g of ammonium chloride to a 2000mL three-necked flask equipped with a magnetic stirrer, a thermometer and a reflux condenser, and add sodium hydroxide, adjust the pH to 7.5, then increase the temperature to 75°C, and react at a constant temperature for 120min to obtain a preliminary mixture.

[0085] Step 1-2, continue to slowly add 350g of solid ammonium chloride to the preliminary mixture, add it over 30 minutes, and keep the temperature of the system at 75°C, add hydrochloric acid to adjust the pH to 5.0, and react at a constant temperature for 120 minutes to obtain a polymer.

[0086] Step 1-3, discharging the material at a constant temperature, and placing the discharged polymer in an open beaker, leaving it to stand under natural conditions, and naturally cooling it to room temperature, until the viscosity of the polymer detected is 70-80 Pa·s, thereby obtaining a dicyandiamide formaldehyde decolorizing agent.

[0087] Step 2, preparing modified zeolite particles, is as follows:

[0088] The zeolite is added into a mortar and ground into powder, and the powder with a particle size of 0.5-1 μm is screened out, and the powder with a particle size greater than 1 μm is poured back into the mortar and ground again until the particle size of all the powders is less than 1 μm, and then 120 g of the zeolite powder with a particle size of 0.5-1 μm is mixed evenly with 40 g of sodium carboxymethyl cellulose glue to form a paste, and then the paste is added into a granulator for granulation, and the particle size of the granules obtained by granulation is controlled to be 20-30 μm, and finally a layer of polyvinyl alcohol glue is coated on the surface of the zeolite particles, and a layer of water-soluble film soluble in 40-45° C. hot water is adhered to the outside of the polyvinyl alcohol glue to obtain modified zeolite particles.

[0089] Step 3, preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, as follows:

[0090] Take 780g of the decolorizer prepared in step 1, 175g of the coagulant aid and 80g of the modified zeolite particles prepared in step 2, mix them evenly, and stir them so that the modified zeolite particles are evenly dispersed in the dicyandiamide formaldehyde decolorizer to obtain an environmentally friendly wastewater high-efficiency decolorization flocculant.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that no modified zeolite particles are added to the flocculant.

[0093] Comparative Example 2

[0094] The difference from Example 1 is that the modified zeolite particles are replaced by an equal amount of zeolite not modified in step 2.

[0095] Comparative Example 3

[0096] The difference from Example 1 is that: in step 2, the zeolite is ground and bonded to form granules to obtain modified zeolite particles, and no polyvinyl alcohol glue layer is coated on the outer surface of the zeolite particles.

[0097] Experiment 1

[0098] Wastewater was taken from a comprehensive wastewater pool of a dyeing and finishing factory in Guangzhou. The wastewater is bright in color, clear and transparent, and in solution form. It mainly contains dye components such as Reactive Brilliant Red X-3B, Disperse Cationic Brilliant Red SD-5GN and Acid Scarlet G. The chromaticity of the wastewater before treatment was detected according to 3. Platinum-cobalt colorimetry in GB11903-1989 "Determination of Chromatism of Water Quality", and the test data was 594°; the CODCr content of the wastewater before treatment was detected according to GB 11914-1989 "Determination of Chemical Oxygen Demand of Water Quality - Dichromate Method", and the test data was 684 mg / L; the mass concentration of ammonia nitrogen in the wastewater before treatment was detected according to HJ535-2009 "Determination of Ammonia Nitrogen in Water Quality - Nessler's Reagent Spectrophotometric Method", and the test data was 17.52 mg / L.

[0099] Take 10 beakers with a capacity of 2000mL, and add 1500mL of the above wastewater to each beaker, stir the wastewater at a speed of 50r / min using an electric stirrer, and add 120mg of the environmentally friendly wastewater high-efficiency decolorizing flocculant prepared in the above embodiments and comparative examples to the beakers while stirring, continue stirring for 1min, then reduce the speed to 35r / min, stir for 10min, let stand for 4h, heat the mixture in the beaker to 40°C, keep warm for 5min, let stand for 2h under natural conditions, continue to increase the temperature to 45°C, keep warm for 5min, and stir at a speed of 50r / min for 10min, let stand for 1h under natural conditions, take the supernatant, and detect and record the chromaticity (°) of the wastewater after treatment according to 3. platinum-cobalt colorimetry in GB11903-1989 "Determination of chromaticity of water quality"; according to GB 11914-1989 "Determination of Chemical Oxygen Demand of Water Quality" Dichromate Method Detect and record the COD of wastewater after treatment Cr Content (mg / L); According to HJ 535-2009 "Determination of Ammonia Nitrogen in Water Quality - Nessler's Reagent Spectrophotometry", the mass concentration of ammonia nitrogen in the wastewater after treatment (mg / L) was detected and recorded. In addition, the turbidity and precipitation of the wastewater after treatment were observed.

[0100] The test data of the above experiments are detailed in Table 1.

[0101] Table 1

[0102]

[0103] According to the data comparison between Example 1 and Comparative Example 1 in Table 1, although the existing decolorant and coagulant aid can be used to treat printing and dyeing wastewater, good decolorization and flocculation effects can be achieved. However, since the decolorization and flocculation effects are mainly achieved by introducing amino groups and imino groups into the dicyandiamide formaldehyde molecular chain, it is easy to cause the treated wastewater to have a high ammonia nitrogen content. By adding modified zeolite particles, it is beneficial to adsorb ammonia nitrogen in the wastewater, so that the ammonia nitrogen content in the wastewater is not easily affected by the decolorant, and it is easier to meet the wastewater discharge standard.

[0104] According to the data comparison of Example 1 and Comparative Example 2 in Table 1, although the effect of reducing the ammonia nitrogen content in the treated wastewater can be achieved by adding zeolite, the zeolite will also affect the amino and imino groups on the decolorant. In addition, the zeolite particles are too large and easily settle at the bottom of the wastewater, making it difficult to be evenly dispersed in the wastewater, which will also have a certain impact on the ammonia nitrogen absorption of the wastewater to a certain extent, and it is not convenient to clean up after treatment. By first grinding the zeolite into powder and then granulating it into a granular state, it is convenient for the modified zeolite particles to be better evenly dispersed in the decolorant, and it is beneficial for the modified zeolite particles to be better evenly dispersed in the wastewater, and it is also beneficial for the subsequent cleaning of the modified zeolite particles.

[0105] According to the data comparison between Example 1 and Comparative Example 3 in Table 1, coating a layer of polyvinyl alcohol glue on the surface of the zeolite particles is beneficial to better protect the modified zeolite particles, so that the modified zeolite particles are less likely to be affected by the decolorization and flocculation effect of the decolorizer due to too rapid dissolution, and are less likely to be directly adsorbed and flocculated by the flocculant due to too rapid dissolution, making it difficult to reduce the ammonia nitrogen content.

[0106] According to the data comparison of Examples 1-4 in Table 1, it can be seen that controlling the reaction conditions of the decolorizing agent is beneficial to better improve the decolorizing and flocculation effect of the decolorizing agent.

[0107] According to the data comparison between Example 1 and Example 5 in Table 1, it can be obtained that by adhering a layer of water-soluble film on the surface of the modified zeolite particles, it is beneficial to better control the dissolution time of the modified zeolite particles, so that the decolorization effect of the decolorizer and the ammonia nitrogen adsorption effect of the zeolite are less likely to be affected, which is beneficial to better improve the decolorization and flocculation effect of the flocculant while also lowering the ammonia nitrogen content in the water.

[0108] According to the data comparison between Example 1 and Example 6 in Table 1, by controlling the particle size of the zeolite powder and the modified zeolite particles and controlling the viscosity of the decolorizer, it is beneficial to better control the dissolution time of the modified zeolite particles, making the decolorizer less susceptible to the influence of the zeolite, and making the zeolite less likely to be directly adsorbed and flocculated by the flocculant, which is beneficial to better improve the decolorization and flocculation effect of the flocculant while also lowering the ammonia nitrogen content in the water.

[0109] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, characterized in that: The following steps are involved: Step 1, preparing dicyandiamide formaldehyde decolorizing agent, is as follows: Step 1-1, by weight, add 80-85 parts by weight of dicyandiamide, 60-65 parts by weight of formaldehyde and 16-19 parts by weight of ammonium chloride into a reaction kettle, raise the temperature to 70-80° C., adjust the pH to 7-8, and react at a constant temperature for 100-130 minutes to obtain a preliminary mixture; Step 1-2, continue to add 34-36 parts by weight of ammonium chloride to the preliminary mixture, increase the temperature to 70-80° C., adjust the pH to 4-5, and react at a constant temperature for 60-120 minutes to obtain a polymer; Step 1-3, discharging the material at a constant temperature, and placing the discharged polymer in an open container and standing until the temperature of the polymer drops to room temperature to form a viscous liquid, thereby obtaining a dicyandiamide formaldehyde decolorizer; Step 2, preparing modified zeolite particles, is as follows: The zeolite is ground into powder, carboxymethyl cellulose glue is added to the powdered zeolite, and the mixture is stirred to form a paste, and the mixture is re-granulated to form zeolite particles, and then a layer of polyvinyl alcohol glue is coated on the surface of the zeolite particles, and the mixture is dried to obtain modified zeolite particles. Step 3, preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant, as follows: By weight, 75-80 parts by weight of the dicyandiamide formaldehyde decolorizer prepared in step 1, 15-20 parts by weight of the coagulant aid and 5-10 parts by weight of the modified zeolite particles prepared in step 2 are mixed and stirred to disperse evenly, thereby obtaining an environmentally friendly wastewater high-efficiency decolorization flocculant.

2. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to claim 1, characterized in that: The reaction temperature in step 1-1 is 70-75°C, the pH value is 7.5-7.6, and the reaction time is 115-120 min; the reaction temperature in step 1-2 is 70-75°C, the pH value is 4.8-5.0, and the reaction time is 110-120 min.

3. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to claim 1, characterized in that: In the step 1-1, a catalyst is also added, and the catalyst is any one of sodium hydroxide, calcium hydroxide, potassium hydroxide, and sodium acetate.

4. A method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to any one of claims 1 to 3, characterized in that: In the step 2, after the surface of the modified zeolite particles is coated with polyvinyl alcohol glue, a water-soluble film is adhered to the surface of the polyvinyl alcohol glue, and the temperature at which the water-soluble film dissolves in water is 40-45°C.

5. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to any one of claims 1 to 3, characterized in that: In the step 2, the particle size of the powdered zeolite powder is 0.5-1 μm.

6. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to claim 5, characterized in that: In the step 2, the particle size of the zeolite particles formed by re-granulation is 20-30 μm.

7. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to claim 6, characterized in that: In the steps 1-3, the viscosity of the dicyandiamide formaldehyde decolorizing agent is 50-80 Pa·s.

8. The method for preparing an environmentally friendly wastewater high-efficiency decolorizing flocculant according to any one of claims 1 to 3, characterized in that: The coagulant aid is polyacrylamide emulsion.

9. An environmentally friendly wastewater high-efficiency decolorizing flocculant, characterized by: The product is prepared by the method for preparing the environmentally friendly wastewater high-efficiency decolorizing flocculant as described in any one of claims 1 to 8.

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