A cationic natural polymer composite flocculant, its preparation method and application

Abstract

The present invention discloses a cationic natural polymer composite flocculant and its preparation method and application. The composite flocculant of the present invention is prepared by graft copolymerization with moringa, starch, and aluminum ash as the main raw materials under the action of an initiator. The aluminum ash is reacted with hydrochloric acid to obtain an aluminum salt solution. After mixing the starch solution and the moringa seed powder, ultrasonic treatment, stirring, and heating are carried out for gelatinization for a period of time. Then, the aluminum salt solution and the initiator are added for graft copolymerization reaction, and finally purification is carried out to obtain the composite flocculant product of the present invention. The raw materials of the cationic natural polymer composite flocculant prepared by the present invention are more economical, environmentally friendly, and have a higher yield compared to the synthetic raw materials of traditional flocculants. Under the same dosage, the cationic natural polymer composite flocculant prepared by the present invention has a higher removal rate for total phosphorus, chromaticity, suspended solids, etc. in paint wastewater and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment flocculants, and particularly to a cationic natural polymer composite flocculant, its preparation method and application, mainly used for treating paint wastewater. Background Art

[0002] With the increase in the number of production enterprises with spraying processes, the treatment of paint wastewater has become a severe problem. The COD, SS, TN, TP, and NH4-N concentrations of this type of wastewater are high, the chromaticity and turbidity are large, the organic matter concentration is high, the composition is complex, and it contains a large amount of toxic and harmful substances. If it cannot be properly treated, it will surely have a serious impact on the ecological environment.

[0003] Currently, the main method for treating this type of wastewater is to add the organic polymer flocculant polyacrylamide to the paint wastewater. The monomer acrylamide, the raw material for preparing this flocculant, forms polyacrylamide through polymerization. Acrylamide is a neurotoxic agent that can damage the nervous system. After poisoning, symptoms such as ataxia and muscle weakness will appear. When treating paint wastewater with the same concentration, the dosage of polyacrylamide flocculant is relatively large, and the synthesis process is expensive and environmentally unfriendly.

[0004] The present invention aims to develop a cationic natural polymer composite flocculant to treat such paint wastewater, and solve problems such as low treatment efficiency, harm to human health, and environmental unfriendliness of traditional flocculants. Summary of the Invention

[0005] In view of the above technical problems existing in the prior art, the purpose of the present invention is to provide a cationic natural polymer composite flocculant, its preparation method and application.

[0006] The preparation method of the described cationic natural polymer composite flocculant is obtained by graft copolymerization with moringa, starch, and aluminum ash as the main raw materials under the action of an initiator. The graft copolymerization method is as follows:

[0007] 1) Make the moringa seeds into powder, wash them clean, and then put them into an oven to dry to obtain moringa seed powder;

[0008] 2) Measure deionized water, add starch and stir evenly to prepare a starch solution;

[0009] 3) Take aluminum ash and react it with hydrochloric acid to obtain an aluminum salt solution;

[0010] 4) Put the starch solution prepared in 2) into a flask, add the moringa seed powder prepared in 1), ultrasonically vibrate for 5 - 30 min, then take out the flask and put it into a water bath for stirring and heating for gelatinization for a period of time, then add the aluminum salt solution prepared in 3) and stir well, and then add an initiator and carry out graft copolymerization reaction under stirring and heating;

[0011] 5) After the graft copolymerization reaction in step 4) is completed, the obtained graft copolymerization solution is cooled at room temperature, washed with a C1-C3 lower alcohol solvent, and after standing and sedimentation, the solvent is filtered off. The residue is refined with a Soxhlet extractor to further remove organic impurities. The refined residue is dried and ground to obtain the cationic natural polymer composite flocculant.

[0012] Further, in step 2), the concentration of the starch solution is 40-200 mg / L, preferably 60-100 mg / L.

[0013] Further, in step 3), the concentration of the aluminum salt solution is 50-200 mg / L, preferably 100 mg / L.

[0014] Further, in step 4), the temperature for heating and gelatinization is 80-90 °C, and the gelatinization time is 1-2 hours.

[0015] Further, in step 4), the temperature of the graft copolymerization reaction is 90-95 °C, and the reaction time is 0.5-2 hours.

[0016] Further, in step 4), the feeding mass ratio of starch to Moringa oleifera seed powder is 4-10:10, and the feeding mass ratio of starch to aluminum salt is 5-10:10, preferably 6:10.

[0017] Further, in step 4), the initiator is potassium persulfate, and the feeding mass ratio of the initiator to the aluminum salt is 2-4:1, preferably 3:1.

[0018] A cationic natural polymer composite flocculant provided by the present invention can be well applied to the treatment of paint wastewater. The application method is as follows: The cationic natural polymer composite flocculant is put into the paint wastewater according to a solid-liquid ratio of 0.01-0.03 g / L, and first reacted at a stirring speed of 150-200 r / min for 2-8 min, then reacted at a stirring speed of 80-120 r / min for 2-5 min, and finally reacted at a stirring speed of 40-60 r / min for 4-10 min. The supernatant after standing is the treated wastewater.

[0019] Further, the total phosphorus concentration of the paint wastewater is 10-20 mg / L, the suspended solid concentration is 100-200 mg / L, and the removal rates of total phosphorus and suspended solids in the treated wastewater can both reach more than 90%.

[0020] The beneficial effects achieved by the present invention are:

[0021] 1) Starch (C6H 10 O5) nIt is a high-molecular carbohydrate with strong coagulation ability. It can coagulate the pollutant particles in sewage by net trapping and then precipitate them. However, the linear molecular structure has a low degree of polymerization, and the net trapping efficiency during coagulation is low, so large flocculants cannot be formed. Based on the characteristics of starch, this invention patent gelatinizes it under ultrasonic and high temperature conditions, breaks the hydrogen bonds and grafts copolymerizes with charged aluminum salts to increase the degree of polymerization and the chain length, improving its ability to flocculate pollutant particles in sewage. Finally, the obtained copolymer is attached to the moringa seed powder to increase the three-dimensional network and enhance the net trapping performance during sedimentation.

[0022] 2) The raw materials of the cationic natural polymer composite flocculant prepared in this invention are more economical, environmentally friendly, and have a higher yield compared with the synthetic raw materials of traditional flocculants. Under the same dosage, the cationic natural polymer composite flocculant prepared in this invention has a higher removal rate of total phosphorus, chromaticity, suspended solids, etc. in paint wastewater. Specific implementation method

[0023] The following further illustrates the present invention with specific examples, but the protection scope of the present invention is not limited thereto.

[0024] In this invention, the paint wastewater comes from Jiada Machinery Factory in Deqing County, Zhejiang Province. Moringa seeds, starch, potassium persulfate, and polyacrylamide (PAM) used in the comparative example are purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The aluminum ash comes from the waste materials of aluminum processing in a certain machinery factory in Zhejiang.

[0025] Example 1:

[0026] (1) Crush the moringa seeds, sieve them with a 200-mesh sieve, take the moringa seed powder below 200 mesh, wash it with deionized water, and put the washed moringa seed powder into an oven at 80 °C for 24 hours to dry, obtaining dry and sterile moringa seed powder;

[0027] (2) Measure 100 mL of deionized water, add 6 mg of starch, and stir evenly at room temperature to obtain a 60 mg / L starch solution;

[0028] (3) Wash and dry the aluminum ash with deionized water, add a certain amount of hydrochloric acid for reaction and then filter. Put the filtered aluminum salt into an oven at 60 °C for 2 hours to dry, weigh 10 mg of aluminum salt, add 100 mL of deionized water, and stir evenly to obtain a 100 mg / L aluminum salt solution;

[0029] (4) Put the starch solution prepared in step (2) into a round-bottom three-neck flask and add 10 mg of the moringa seed powder prepared in (1), and ultrasonically oscillate for 20 - 30 min;

[0030] (5) Take out the round-bottomed three-necked flask in step (4) from the ultrasonic bath and place it in a water bath for stirring at a stirring speed of 50 r / min. Heat it to 85 °C under stirring for gelatinization for 1.5 hours. Then add the aluminum salt solution prepared in step (3) into the round-bottomed three-necked flask and stir at a stirring speed of 100 r / min for 30 min. Add 30 mg of initiator potassium persulfate and stir at 90 - 95 °C at a stirring speed of 90 r / min for graft copolymerization for 1 hour to obtain a gelatinized copolymer.

[0031] (6) Cool the gelatinized copolymer prepared in step (5) at room temperature, add ethanol for washing, let it stand for sedimentation and then filter to separate the solvent. Further remove organic impurities by refining with a Soxhlet extractor. After drying and grinding the refined residue, obtain natural polymer composite flocculant powder 1.

[0032] (7) Take 500 mL of paint wastewater and place it in a beaker. Add 10 mg of flocculant powder 1 and stir at a stirring speed of 200 r / min for 5 min, then stir at a stirring speed of 100 r / min for 3 min, and then stir at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid at 1 - 2 cm below the liquid surface, and the results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0033] Example 2:

[0034] (1) Crush the moringa seeds and sieve them through a 200-mesh sieve. Take the moringa seed powder below 200 mesh and wash it with deionized water. Put the washed moringa seed powder into an oven at 80 °C for 24 hours of drying to obtain dry and sterile moringa seed powder.

[0035] (2) Measure 100 mL of deionized water, add 8 mg of starch, and stir evenly at room temperature to obtain an 80 mg / L starch solution.

[0036] (3) Wash the aluminum ash with deionized water and dry it. Add a certain amount of hydrochloric acid for reaction and then filter. Put the filtered aluminum salt into an oven at 60 °C for 2 hours of drying, weigh 10 mg of aluminum salt, add 100 mL of deionized water, and stir evenly to obtain a 100 mg / L aluminum salt solution.

[0037] (4) Put the starch solution prepared in step (2) into a round-bottomed three-necked flask and add 10 mg of the moringa seed powder prepared in (1), and perform ultrasonic oscillation for 20 - 30 min.

[0038] (5) Take out the round-bottomed three-necked flask in step (4) from the ultrasonic bath and place it in a water bath for stirring at a stirring speed of 50 r / min. Heat it to 85 °C for gelatinization for 1.5 hours under stirring. Then add the aluminum salt solution prepared in step (3) to the round-bottomed three-necked flask and stir at a stirring speed of 100 r / min for 30 min. Add 30 mg of initiator potassium persulfate and stir at 90-95 °C at a stirring speed of 90 r / min for graft copolymerization for 1 hour to obtain a gelatinized copolymer.

[0039] (6) Cool the gelatinized copolymer prepared in step (5) at room temperature, add ethanol for washing, let it stand for sedimentation and then filter to separate the solvent. Use a Soxhlet extractor for further purification to remove organic impurities. After drying and grinding the purified residue, the natural polymer composite flocculant powder 2 is obtained.

[0040] (7) Take 500 mL of paint wastewater and place it in a beaker. Add 10 mg of flocculant powder 2 and stir at a speed of 200 r / min for 5 min, then stir at a speed of 100 r / min for 3 min, and then stir at a speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid 1-2 cm below the liquid surface, and the results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0041] Example 3:

[0042] (1) Crush the moringa seeds and sieve them through a 200-mesh sieve. Take the moringa seed powder below 200 mesh and wash it with deionized water. Put the washed moringa seed powder into an oven at 80 °C for 24 hours to dry to obtain dry and sterile moringa seed powder.

[0043] (2) Measure 100 mL of deionized water, add 10 mg of starch, and stir evenly at room temperature to obtain a 100 mg / L starch solution.

[0044] (3) Wash the aluminum ash with deionized water and dry it. Add a certain amount of hydrochloric acid for reaction and then filter. Put the filtered aluminum salt into an oven at 60 °C for 2 hours to dry and then weigh 10 mg of aluminum salt. Add 100 mL of deionized water and stir evenly to obtain a 100 mg / L aluminum salt solution.

[0045] (4) Put the starch solution prepared in step (2) into a round-bottomed three-necked flask and add 10 mg of the moringa seed powder prepared in (1), and perform ultrasonic oscillation for 20-30 min.

[0046] (5) Take out the round-bottomed three-necked flask in step (4) from the ultrasonic bath and place it in a water bath for stirring at a stirring speed of 50 r / min. Heat it to 85 °C under stirring for gelatinization for 1.5 hours. Then add the aluminum salt solution prepared in step (3) to the round-bottomed three-necked flask and stir at a stirring speed of 100 r / min for 30 min. Add 30 mg of initiator potassium persulfate and stir at 90-95 °C at a stirring speed of 90 r / min for graft copolymerization for 1 hour to obtain a gelatinized copolymer.

[0047] (6) Cool the gelatinized copolymer prepared in step (5) at room temperature, add ethanol for washing, let it stand for sedimentation and then filter to separate the solvent. Further remove organic impurities with a Soxhlet extractor. After drying and grinding the refined residue, the natural polymer composite flocculant powder 3 is obtained.

[0048] (7) Take 500 mL of paint wastewater and place it in a beaker. Add 10 mg of flocculant powder 3, stir at a speed of 200 r / min for 5 min, stir at a speed of 100 r / min for 3 min, and stir at a speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid at 1-2 cm below the liquid surface, and the results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0049] Example 4:

[0050] (1) Crush the moringa seeds, sieve them with a 200-mesh sieve, take the moringa seed powder below 200 mesh, wash it with deionized water, and put the washed moringa seed powder into an oven at 80 °C for 24 hours of drying to obtain dry and sterile moringa seed powder;

[0051] (2) Measure 100 mL of deionized water, add 8 mg of starch, and stir evenly at room temperature to obtain an 80 mg / L starch solution;

[0052] (3) Wash the aluminum ash with deionized water and dry it. Add a certain amount of hydrochloric acid for reaction and then filter. The filtered aluminum salt is placed in an oven at 60 °C for 2 hours of drying, weigh 10 mg of aluminum salt, add 100 mL of deionized water, and stir evenly to obtain a 100 mg / L aluminum salt solution;

[0053] (4) Put the starch solution prepared in step (2) into a round-bottomed three-necked flask and add 20 mg of the moringa seed powder prepared in (1), and perform ultrasonic oscillation for 20-30 min;

[0054] (5) Take out the round-bottom three-necked flask in step (4) from the ultrasonic bath and place it in a water bath for stirring at a stirring speed of 50 r / min. Heat it to 85 °C under stirring for gelatinization for 1.5 hours. Then add the aluminum salt solution prepared in step (3) to the round-bottom three-necked flask and stir at a stirring speed of 100 r / min for 30 min. Add 30 mg of initiator potassium persulfate and stir at 90 - 95 °C at a stirring speed of 90 r / min for graft copolymerization for 1 hour to obtain the gelatinized copolymer.

[0055] (6) Cool the gelatinized copolymer prepared in step (5) at room temperature, add ethanol for washing, let it stand for sedimentation and then filter to separate the solvent. Further remove organic impurities by refining with a Soxhlet extractor. After drying and grinding the refined residue, the natural polymer composite flocculant powder 4 is obtained.

[0056] (7) Take 500 ml of paint wastewater and place it in a beaker. Add 10 mg of flocculant powder 4 and stir at a stirring speed of 200 r / min for 5 min, then stir at a stirring speed of 100 r / min for 3 min, and then stir at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid at 1 - 2 cm below the liquid surface. The results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0057] Comparative Example 1:

[0058] Take 500 mL of paint wastewater and place it in a beaker. Add 20 mg of polyacrylamide (PAM) and stir at a stirring speed of 200 r / min for 5 min, then stir at a stirring speed of 100 r / min for 3 min, and then stir at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid at 1 - 2 cm below the liquid surface. The results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0059] Comparative Example 2:

[0060] Take 500 mL of paint wastewater and place it in a beaker. Add 20 mg of polyaluminum chloride (PAC) and stir at a stirring speed of 200 r / min for 5 min, then stir at a stirring speed of 100 r / min for 3 min, and then stir at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the clear liquid at 1 - 2 cm below the liquid surface. The results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0061] Comparative Example 3:

[0062] Take 500 mL of paint wastewater and place it in a beaker. Add 20 mg of starch, react at a stirring speed of 200 r / min for 5 min, react at a stirring speed of 100 r / min for 3 min, and react at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the supernatant at a depth of 1 - 2 cm below the liquid surface, and the measured results of total phosphorus, chromaticity, and suspended solids are listed in Tables 1, 2, and 3.

[0063] Comparative Example 4:

[0064] Wash the aluminum ash with deionized water and dry it. Add a certain amount of hydrochloric acid and react, then filter. Put the filtered aluminum salt in an oven at 60 °C and dry it for 2 hours, and then weigh 20 mg of the aluminum salt.

[0065] Take 500 mL of paint wastewater and place it in a beaker. Add 20 mg of aluminum salt, react at a stirring speed of 200 r / min for 5 min, react at a stirring speed of 100 r / min for 3 min, and react at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the supernatant at a depth of 1 - 2 cm below the liquid surface, and measure the total phosphorus, chromaticity, and suspended solids.

[0066] Comparative Example 5:

[0067] Crush the moringa seeds, sieve them with a 200 - mesh sieve, take the moringa seed powder below 200 - mesh and wash it with deionized water. Put the washed moringa seed powder in an oven at 80 °C and dry it for 24 hours to obtain dry and sterile moringa seed powder.

[0068] Take 500 mL of paint wastewater and place it in a beaker. Add 20 mg of moringa seed powder, react at a stirring speed of 200 r / min for 5 min, react at a stirring speed of 100 r / min for 3 min, and react at a stirring speed of 50 r / min for 6 min. After standing for 40 min, take the supernatant at a depth of 1 - 2 cm below the liquid surface, and measure the total phosphorus, chromaticity, and suspended solids.

[0069] Application Example:

[0070] According to the above test method, the flocculants prepared in Examples 1 to 4, as well as Comparative Examples 1 - 5, the treatment effects on paint wastewater are listed in Tables 1, 2, and 3. Among them, the total phosphorus, chromaticity, and suspended solid indexes of the paint wastewater raw materials are the same, and are listed in Tables 1, 2, and 3.

[0071]

[0072]

[0073]

[0074] As can be seen from Table 1-3, when compared with Comparative Examples 1-5, the cationic natural polymer composite flocculants prepared in Examples 1 to 4 of the present invention have obvious effects on total phosphorus, chromaticity, and suspended solids, and the removal rates can be as high as 94.1%, 97.0%, and 90.0%.

[0075] Comparing Examples 1, 2, and 3, for the cationic natural polymer composite flocculants 1-3 prepared, the removal rates of total phosphorus, chromaticity, and suspended solids in paint wastewater by Flocculant 1 are better than those of others. Therefore, the mass ratio of starch to aluminum salt during the preparation process is 0.6-1.0:1 (more preferably 0.6:1).

[0076] Comparing Examples 1 and 4, for the cationic natural polymer composite flocculants 1 and 4 prepared, the removal rates of total phosphorus, chromaticity, and suspended solids in paint wastewater by Flocculant 1 are better than those of Flocculant 4. Therefore, the addition amount of moringa seed powder is 10 mg during the preparation process, and the treatment effect is the best.

[0077] Compared with the traditional flocculants in Comparative Examples 1 and 2, the cationic natural polymer composite flocculant prepared in the present invention has a better treatment effect on paint wastewater. This may be because the starch with a linear molecular structure gelatinizes under ultrasonic and high-temperature conditions to break hydrogen bonds and graft copolymerize with the charged aluminum salt to increase its degree of polymerization, improving its ability to flocculate pollutant particles in sewage. Finally, the obtained copolymer is attached to the moringa seed powder to increase the three-dimensional network and enhance the net capture performance during sedimentation.

[0078] The content described in this specification is only a list of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the examples.

Claims

1. A preparation method of a cationic natural polymer composite flocculant, characterized in that It is prepared by graft copolymerization with moringa seeds, starch, and aluminum ash as the main raw materials under the action of an initiator. The graft copolymerization method is as follows: 1) Make the moringa seeds into powder, wash them clean, and then put them into an oven to dry to obtain moringa seed powder; 2) Measure deionized water, add starch and stir evenly to prepare a starch solution; 3) Take aluminum ash and react it with hydrochloric acid to obtain an aluminum salt solution; 4) Put the starch solution prepared in 2) into a flask, add the moringa seed powder prepared in 1), ultrasonically vibrate for 5 - 30 min, then take out the flask and put it into a water bath to stir and heat for gelatinization for a period of time, then add the aluminum salt solution prepared in 3) and stir well, then add an initiator and carry out graft copolymerization reaction under stirring and heating; 5) After the graft copolymerization reaction in step 4) ends, the obtained graft copolymer solution is cooled at room temperature, washed with a C1 - C3 lower alcohol solvent, allowed to stand and settle, then the solvent is filtered off, and further refined with a Soxhlet extractor to remove organic impurities. The refined residue is dried and ground to obtain the cationic natural polymer composite flocculant; In step 4), the temperature for heating gelatinization is 80 - 90 °C, and the gelatinization time is 1 - 2 hours; In step 4), the temperature for the graft copolymerization reaction is 90 - 95 °C, and the reaction time is 0.5 - 2 hours; In step 2), the concentration of the starch solution is 40 - 200 mg / L; In step 3), the concentration of the aluminum salt solution is 50 - 200 mg / L; In step 4), the feeding mass ratio of starch to moringa seed powder is 4 - 10:10, and the feeding mass ratio of starch to aluminum salt is 5 - 10:10; In step 4), the initiator is potassium persulfate, and the feeding mass ratio of the initiator to the aluminum salt is 2 - 4:

1.

2. The preparation method of a cationic natural polymer composite flocculant as described in claim 1, characterized in that In step 2), the concentration of the starch solution is 60 - 100 mg / L.

3. The preparation method of a cationic natural polymer composite flocculant according to claim 1, characterized in that In step 3), the concentration of the aluminum salt solution is 100 mg / L.

4. The preparation method of a cationic natural polymer composite flocculant according to claim 1, characterized in that In step 4), the feeding mass ratio of starch to aluminum salt is 6:

10.

5. The preparation method of a cationic natural polymer composite flocculant as described in claim 1, characterized in that In step 4), the feeding mass ratio of the initiator to the aluminum salt is 3:

1.

6. A cationic natural polymer composite flocculant prepared by the method according to any one of claims 1 - 5.

7. Use of a cationic natural polymer composite flocculant as described in claim 6 in treating paint wastewater, characterized in that Put the cationic natural polymer composite flocculant into the paint wastewater according to a solid - liquid ratio of 0.01 - 0.03 g / L. First, react at a stirring speed of 150 - 200 r / min for 2 - 8 min, then react at a stirring speed of 80 - 120 r / min for 2 - 5 min, and finally react at a stirring speed of 40 - 60 r / min for 4 - 10 min. The supernatant after standing is the treated wastewater.

8. The application according to claim 7, wherein The total phosphorus concentration of the paint wastewater is 10 - 20 mg / L, and the suspended solid concentration is 100 - 200 mg / L.

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