Preparation method of polyaluminum ferric sulfate composite water purifying agent

Abstract

The invention discloses a preparation method of a polyaluminum ferric sulfate composite water purifying agent, and belongs to the technical field of water purifying agents. Comprising the following raw materials in parts by weight: 33-45 parts of polyaluminum ferric sulfate, 21-37 parts of modified polyacrylamide and 80-100 parts of deionized water. The water purifying agent prepared by the preparation method disclosed by the invention is simultaneously combined with an aluminum-based water purifying agent, an iron-based water purifying agent and a polyacrylamide water purifying agent which can achieve a synergistic effect, so that the water purifying performance is improved; the polyacrylamide is subjected to cationic modification, so that the flocculation effect of the polyacrylamide is stronger, and the polyacrylamide also has sterilization performance; in conclusion, the prepared water purifying agent combines the advantages of three water purifying agents at the same time, has excellent flocculation effect and sterilization performance, overcomes the defects of a single component, and can adapt to more complex water quality; the important application value is realized in the technical field of water purifying agents.

Description

Technical Field

[0001] The present invention belongs to the technical field of water purifying agents, and specifically relates to a preparation method of a polyaluminum ferric sulfate composite water purifying agent. Background Art

[0002] With the acceleration of the industrialization process and the expansion of the scope of human activities, the problem of water body pollution has become a core challenge in global environmental governance. Among various water treatment technologies, the water purification precipitation method has always occupied an important position due to its simple operation, low cost, and remarkable removal effect on suspended solids, colloidal substances, and some dissolved pollutants. As the core material in the water purification process, inorganic polymer water purifying agents, relying on their multiple action mechanisms such as electric neutralization and adsorption bridging, have gradually replaced traditional low-molecular water purifying agents such as aluminum salts and iron salts and become a research hotspot in the modern water treatment field.

[0003] Commonly used inorganic polymer water purifying agents include polyaluminum sulfate (PAS) and polyferric sulfate (PFS). Due to their high charge density and molecular polymerization degree, they are widely used in the fields of drinking water purification and industrial wastewater treatment. However, single-component water purifying agents have gradually revealed limitations in practical applications. For example, the water purification effect of polyaluminum sulfate significantly decreases in low-temperature and low-turbidity water bodies, and the residual aluminum ions may pose health risks; while polyferric sulfate has strong ability to remove organic matter, but its strong acidity is easy to corrode treatment equipment, and it is prone to color reversion when treating high-color wastewater. Therefore, to overcome the defects of single water purifying agents, existing research has compounded the two to prepare aluminum-iron composite water purifying agents. The composite water purifying agents can not only improve the flocculation effect of the water purifying agent through the synergistic effect of aluminum and iron ions, but also overcome the problems of high cost of aluminum salts, harm to the human body caused by residual aluminum ions, and easy yellowing and blackening of iron salts. Although the aluminum-iron composite water purifying agent has good flocculation effect, for some complex water qualities, there are still some impurity pollutants that cannot be effectively removed. In view of the above problems, there is an urgent need to invent a polyaluminum ferric sulfate composite water purifying agent with excellent flocculation effect to meet the higher requirements in the technical field of water purifying agents. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a preparation method of a polyaluminum ferric sulfate composite water purifying agent.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of a polyaluminum ferric sulfate composite water purifying agent, comprising the following steps:

[0007] Mix polyaluminum ferric sulfate, modified polyacrylamide, and deionized water, perform magnetic stirring at room temperature, then perform ultrasonic dispersion. After uniform dispersion, ripen for 3 - 4 h, filter, and dry the filter residue in an oven to obtain the polyaluminum ferric sulfate composite water purifying agent.

[0008] Further, the raw materials are as follows by weight parts: 33 - 45 parts of polyaluminum ferric sulfate, 21 - 37 parts of modified polyacrylamide, and 80 - 100 parts of deionized water.

[0009] Further, the conditions for magnetic stirring are a rotation speed of 300 - 500 rpm and stirring for 20 - 30 min.

[0010] Further, the time for ultrasonic dispersion is 60 - 120 min and the frequency is 30 - 40 kHz.

[0011] Further, the polyaluminum ferric sulfate is prepared through the following steps:

[0012] Add ferrous sulfate and aluminum nitrate into sulfuric acid solution, under a constant temperature water bath at 80 - 90 °C, process for 2 - 3 h, then add an oxidant, keep the temperature for reaction for 30 - 60 min. After the reaction is completed, filter. Wait until the filtrate cools down to 50 - 60 °C, then dropwise add sodium hydroxide solution to adjust the pH of the solution to 3 - 4, and then carry out aging for 1 - 2 h. Finally, place it in an oven for drying to obtain polyaluminum ferric sulfate.

[0013] Further, the dosage ratio of ferrous sulfate, aluminum nitrate, sulfuric acid solution, and oxidant is 15.7 g: 12.6 g: 100 mL: 1.3 g.

[0014] Further, the oxidant is one of hydrogen peroxide, potassium chlorate, and sodium hypochlorite.

[0015] By compounding the iron - based and aluminum - based water purifying agents, the prepared polyaluminum ferric sulfate has both excellent properties of the two. It has large flocs, fast flocculation and sedimentation speed, good water purification effect, and also significantly reduces the content of harmful substances such as heavy metals in water.

[0016] Further, the modified polyacrylamide is prepared through the following steps:

[0017] Step 1: Use a three - necked flask equipped with a magnetic stirrer, thermometer, and condenser as the reaction device. Add triphenylphosphine, 3 - chloropropionic acid, and sodium iodide into the device. Use toluene as the reaction solvent. After stirring and mixing, heat the device to 80 °C and stir for 3 h. After the reaction is completed, cool to room temperature, remove toluene by vacuum distillation, add n - hexane, filter by suction, wash with cold ether, and dry in vacuum to obtain an intermediate product;

[0018] Triphenylphosphine and 3 - chloropropionic acid undergo an SN2 reaction, and sodium iodide catalyzes the reaction to obtain a quaternary phosphonium product; the specific reaction process is as follows:

[0019]

[0020] Step 2: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add the intermediate product, 2-hydroxyethyl acrylate, dicyclohexylcarbodiimide, and zinc chloride to the apparatus. Use toluene as the reaction solvent. After stirring and mixing, heat the apparatus to 90 °C and stir the reaction for 6 h. After the reaction is completed, cool it to room temperature, remove part of the solvent by vacuum distillation, and then purify it by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 4:1). Rotate evaporate to remove the eluent to obtain the modifier;

[0021] An esterification reaction occurs between the carboxyl group in the intermediate product molecule and the hydroxyl group in the 2-hydroxyethyl acrylate molecule. Dicyclohexylcarbodiimide and zinc chloride act as catalysts to obtain the modifier. The specific reaction process is as follows:

[0022]

[0023] Step 3: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add Span 80, Tween 80, the modifier, and cyclohexane to the apparatus. Then add acrylamide, dimethyldiallylammonium chloride, and methylenebisacrylamide to distilled water and stir continuously until completely dissolved to obtain a mixed solution. Add this solution to the flask, emulsify for 30 min, then add azobisisobutyronitrile, and introduce nitrogen as the protective gas. Heat to 70 °C and stir the reaction for 6 h. After the reaction is completed, demulsify, filter, and dry under vacuum to obtain the modified polyacrylamide;

[0024] Azobisisobutyronitrile acts as an initiator to cause a copolymerization reaction between the raw materials to obtain the modified polyacrylamide.

[0025] Furthermore, in Step 1, the dosage ratio of triphenylphosphine, 3-chloropropionic acid, sodium iodide, and toluene is 26.1 g: 10.8 g: 0.3 g: 100 mL.

[0026] Furthermore, in Step 2, the dosage ratio of the intermediate product, 2-hydroxyethyl acrylate, dicyclohexylcarbodiimide, zinc chloride, and toluene is 33.2 g: 11.6 g: 20.6 g: 1.7 g: 120 mL.

[0027] Furthermore, in Step 3, the dosage ratio of Span 80, Tween 80, the modifier, cyclohexane, acrylamide, dimethyldiallylammonium chloride, methylenebisacrylamide, distilled water, and azobisisobutyronitrile is 1.6 g: 2.7 g: 7.9 g: 50 mL: 10.4 g: 5.3 g: 6.1 g: 100 mL: 0.8 g.

[0028] The molecular chain of polyacrylamide can be fixed on the surfaces of different particles, forming a bridge between sludge colloid particles and the polymer. Meanwhile, the polar groups on the molecular chain adsorb the dispersed particles, enabling the particles to form large aggregates and settle, thereby improving the flocculation effect of the water purifying agent. By modifying polyacrylamide, the prepared modified polyacrylamide is a cationic polyacrylamide with ammonium salts on its molecular chain. As positively charged active groups, they can neutralize the colloidal negative charges in sewage or sludge to cause flocculation, improving the flocculation effect of the water purifying agent. Moreover, the modified polyacrylamide molecule also contains quaternary phosphonium salt groups. As positively charged groups, they further enhance the flocculation effect of the water purifying agent. At the same time, the quaternary phosphonium salt can bind to the negatively charged microbial cell membrane through electrostatic adsorption, destroying the cell membrane structure. It can also enter the microorganism and bind to key enzymes or DNA, inhibiting its metabolic activities, endowing polyacrylamide with excellent bactericidal properties.

[0029] Advantages of the present invention:

[0030] 1. The water purifying agent prepared in the present invention combines aluminum-based, iron-based, and polyacrylamide water purifying agents at the same time, and they can synergistically enhance the effect and improve the water purification performance.

[0031] 2. By carrying out cationic modification on polyacrylamide, not only is the flocculation effect of polyacrylamide stronger, but it also has bactericidal properties.

[0032] In summary, the water purifying agent prepared in the present invention combines the advantages of the three water purifying agents at the same time, has excellent flocculation effect and bactericidal properties, overcomes the defects of single components, and can adapt to more complex water qualities; it has important application value in the technical field of water purifying agents. Specific implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0034] Example 1

[0035] Prepare modified polyacrylamide:

[0036] Step 1: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 26.1 g of triphenylphosphine, 10.8 g of 3-chloropropionic acid, and 0.3 g of sodium iodide to the apparatus. Use 100 mL of toluene as the reaction solvent. After stirring and mixing, heat the apparatus to 80 °C and stir the reaction for 3 h. After the reaction is completed, cool it to room temperature, remove toluene by vacuum distillation, add n-hexane, filter by suction, wash with cold ether, and dry under vacuum to obtain an intermediate product;

[0037] Step 2: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 33.2 g of the intermediate product, 11.6 g of 2-hydroxyethyl acrylate, 20.6 g of dicyclohexylcarbodiimide, and 1.7 g of zinc chloride to the apparatus. Use 120 mL of toluene as the reaction solvent. After stirring and mixing, heat the apparatus to 90 °C and stir the reaction for 6 h. After the reaction is completed, cool it to room temperature, remove part of the solvent by vacuum distillation, and then purify it by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 4:1). Rotate and evaporate to remove the eluent to obtain a modifier;

[0038] Step 3: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 1.6 g of Span 80, 2.7 g of Tween 80, 7.9 g of the modifier, and 50 mL of cyclohexane to the apparatus. Then dissolve 10.4 g of acrylamide, 5.3 g of dimethyldiallylammonium chloride, and 6.1 g of methylenebisacrylamide in 100 mL of distilled water, and stir continuously until completely dissolved to obtain a mixed solution. Add this solution to the flask, emulsify for 30 min, then add 0.8 g of azobisisobutyronitrile, and introduce nitrogen as a protective gas. Heat to 70 °C and stir the reaction for 6 h. After the reaction is completed, demulsify, filter, and dry under vacuum to obtain modified polyacrylamide.

[0039] Example 2

[0040] Preparation of modified polyacrylamide:

[0041] Step 1: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 52.2 g of triphenylphosphine, 21.6 g of 3-chloropropionic acid, and 0.6 g of sodium iodide to the apparatus. Use 200 mL of toluene as the reaction solvent. After stirring and mixing, heat the apparatus to 80 °C and stir the reaction for 3 h. After the reaction is completed, cool it to room temperature, remove toluene by vacuum distillation, add n-hexane, filter by suction, wash with cold ether, and dry under vacuum to obtain an intermediate product;

[0042] Step 2: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 66.4 g of the intermediate product, 23.2 g of hydroxyethyl acrylate, 41.2 g of dicyclohexylcarbodiimide, and 3.4 g of zinc chloride to the apparatus. Use 240 mL of toluene as the reaction solvent. After stirring and mixing, heat the apparatus to 90 °C and stir for 6 h. After the reaction is completed, cool to room temperature, remove part of the solvent by reduced pressure distillation, and then purify by silica gel column chromatography (the eluent is petroleum ether and ethyl acetate, and the volume ratio of the two is 4:1). Rotate and evaporate to remove the eluent to obtain the modifier.

[0043] Step 3: Use a three-necked flask equipped with a magnetic stir bar, a thermometer, and a condenser as the reaction apparatus. Add 3.2 g of Span 80, 5.4 g of Tween 80, 15.8 g of the modifier, and 100 mL of cyclohexane to the apparatus. Then add 20.8 g of acrylamide, 10.6 g of dimethyldiallylammonium chloride, and 12.2 g of methylenebisacrylamide to 200 mL of distilled water, and stir continuously until completely dissolved to obtain a mixed solution. Add this solution to the flask, emulsify for 30 min, then add 1.6 g of azobisisobutyronitrile, and introduce nitrogen as the protective gas. Heat to 70 °C and stir for 6 h. After the reaction is completed, demulsify, filter, and dry in vacuo to obtain the modified polyacrylamide.

[0044] Example 3

[0045] Prepare polyaluminum ferric sulfate:

[0046] Add 15.7 g of ferrous sulfate and 12.6 g of aluminum nitrate to 100 mL of sulfuric acid solution (mass fraction 28%). Under a constant temperature water bath at 80 °C, treat for 2 h, then add 1.3 g of hydrogen peroxide, and keep the temperature for 30 min. After the reaction is completed, filter. After waiting for the filtrate to cool to 50 °C, add sodium hydroxide solution (mass fraction 12%) to adjust the pH of the solution to 3, then carry out aging for 1 h, and finally place it in a drying oven for drying to obtain polyaluminum ferric sulfate.

[0047] Example 4

[0048] Prepare polyaluminum ferric sulfate:

[0049] Add 15.7 g of ferrous sulfate and 12.6 g of aluminum nitrate to 100 mL of sulfuric acid solution (mass fraction 28%). Under a constant temperature water bath at 90 °C, treat for 3 h, then add 1.3 g of sodium hypochlorite, and keep the temperature for 60 min. After the reaction is completed, filter. After waiting for the filtrate to cool to 60 °C, add sodium hydroxide solution (mass fraction 12%) to adjust the pH of the solution to 4, then carry out aging for 2 h, and finally place it in a drying oven for drying to obtain polyaluminum ferric sulfate.

[0050] Example 5

[0051] Mix 33 g of the polyaluminum ferric sulfate prepared in Example 3, 21 g of the modified polyacrylamide prepared in Example 1 and 80 g of deionized water, and stir magnetically at a speed of 300 rpm at room temperature for 20 min. Then, ultrasonically disperse at a frequency of 30 kHz for 60 min. After uniform dispersion, age for 3 h, filter, and dry the filter residue in an oven to obtain a polyaluminum ferric sulfate composite water purifying agent.

[0052] Example 6

[0053] Mix 39 g of the polyaluminum ferric sulfate prepared in Example 3, 29 g of the modified polyacrylamide prepared in Example 1 and 90 g of deionized water, and stir magnetically at a speed of 400 rpm at room temperature for 30 min. Then, ultrasonically disperse at a frequency of 35 kHz for 90 min. After uniform dispersion, age for 4 h, filter, and dry the filter residue in an oven to obtain a polyaluminum ferric sulfate composite water purifying agent.

[0054] Example 7

[0055] Mix 45 g of the polyaluminum ferric sulfate prepared in Example 3, 37 g of the modified polyacrylamide prepared in Example 1 and 100 g of deionized water, and stir magnetically at a speed of 500 rpm at room temperature for 30 min. Then, ultrasonically disperse at a frequency of 40 kHz for 120 min. After uniform dispersion, age for 4 h, filter, and dry the filter residue in an oven to obtain a polyaluminum ferric sulfate composite water purifying agent.

[0056] Comparative Example 1

[0057] In the preparation process of Example 7, only replace the modified polyacrylamide with an equal amount of ordinary polyacrylamide, and keep the other conditions unchanged to prepare a water purifying agent.

[0058] Comparative Example 2

[0059] Use a commercially available polyaluminum sulfate water purifying agent.

[0060] Perform the following performance tests on Examples 5, 6, 7 and Comparative Examples 1 and 2:

[0061] Bactericidal rate detection: At room temperature, culture multiple portions of bacterial suspensions in petri dishes, add the test samples to the bacterial suspensions and shake well, and culture for 7 days; count the number of colonies under a microscope before and 7 days after the test samples are placed in the petri dishes, and calculate the bactericidal rate;

[0062] Heavy metal ion removal rate detection: Add the test samples to the water samples polluted by heavy metal ions, use atomic absorption spectrometry (AAS) to measure the heavy metal ion concentrations in the water samples before and after treatment, and calculate the heavy metal ion removal rate;

[0063] COD removal rate detection: Add the test sample to industrial wastewater, use the potassium dichromate method to measure the COD values of the water samples before and after treatment, and calculate the COD removal rate;

[0064] Turbidity detection: Add the same mass of the test sample to the raw water with an average turbidity of 4.1 NTU. After stirring evenly, let it stand and precipitate for 10 minutes, and take the supernatant to measure its turbidity with a turbidimeter; the smaller the turbidity, the stronger the flocculation effect;

[0065] The measured results are shown in the following table:

[0066]

[0067]

[0068] As can be seen from the above table, the bactericidal rate, heavy metal ion removal rate, COD removal rate and flocculation effect of the water purifying agent prepared in the embodiment of the present invention are stronger than those of the comparative example. Therefore, the present invention has important application value in the technical field of water purifying agents.

[0069] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0070] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, which should all fall within the protection scope of the present invention.

Claims

1. A preparation method of a polyaluminum ferric sulfate composite water purifying agent, characterized in that, It includes the following steps: Mix and stir polyaluminum ferric sulfate, modified polyacrylamide and deionized water, disperse by ultrasonic wave, ripen, filter, dry the filter residue to obtain the polyaluminum ferric sulfate composite water purifying agent.

2. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 1, characterized in that, The modified polyacrylamide is prepared through the following steps: Step 1: Mix triphenylphosphine, 3-chloropropionic acid, sodium iodide and toluene, stir and react at 80 °C for 3 h. After the reaction is completed, cool to room temperature, distill under reduced pressure, add n-hexane, filter by suction, wash, and dry in vacuum to obtain an intermediate product. Step 2: Mix the intermediate product, hydroxyethyl acrylate, dicyclohexylcarbodiimide, zinc chloride and toluene, stir and react at 90 °C for 6 h after mixing. After the reaction is completed, cool to room temperature, distill under reduced pressure, purify by column chromatography, and rotary evaporate to obtain a modifier. Step 3: Add Span 80, Tween 80, the modifier and cyclohexane into a flask. Then dissolve acrylamide, dimethyldiallylammonium chloride and methylenebisacrylamide in distilled water, add it into the flask after dissolution, emulsify for 30 min, then add azobisisobutyronitrile, introduce nitrogen, react at 70 °C for 6 h. After the reaction is completed, demulsify, filter, and dry to obtain the modified polyacrylamide.

3. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 2, characterized in that In Step 1, the dosage ratio of triphenylphosphine, 3-chloropropionic acid, sodium iodide and toluene is 26.1 g: 10.8 g: 0.3 g: 100 mL.

4. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 2, characterized in that, In Step 2, the dosage ratio of the intermediate product, hydroxyethyl acrylate, dicyclohexylcarbodiimide, zinc chloride and toluene is 33.2 g: 11.6 g: 20.6 g: 1.7 g: 120 mL.

5. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 2, characterized in that, In Step 3, the dosage ratio of Span 80, Tween 80, the modifier, cyclohexane, acrylamide, dimethyldiallylammonium chloride, methylenebisacrylamide, distilled water, and azobisisobutyronitrile is 1.6 g: 2.7 g: 7.9 g: 50 mL: 10.4 g: 5.3 g: 6.1 g: 100 mL: 0.8 g.

6. The preparation method of a polymeric ferric aluminum sulfate composite water purifying agent according to claim 1, wherein, Each raw material is as follows by weight parts: 33-45 parts of polyaluminum ferric sulfate, 21-37 parts of modified polyacrylamide, 80-100 parts of deionized water.

7. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 1, characterized in that, The polyaluminum ferric sulfate is prepared through the following steps: Add ferrous sulfate and aluminum nitrate into sulfuric acid solution, treat under a constant temperature water bath at 80-90 °C for 2-3 h, then add an oxidant, keep the temperature for reaction for 30-60 min. After the reaction is completed, filter. Wait for the filtrate to cool to 50-60 °C, then adjust the pH of the solution to 3-4, ripen for 1-2 h, and dry to obtain the polyaluminum ferric sulfate.

8. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 7, characterized in that, The dosage ratio of ferrous sulfate, aluminum nitrate, sulfuric acid solution and oxidant is 15.7 g: 12.6 g: 100 mL: 1.3 g.

9. The preparation method of a polyaluminum ferric sulfate composite water purifying agent according to claim 7, characterized in that, The oxidant is one of hydrogen peroxide, potassium chlorate and sodium hypochlorite.

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