Calcium sulfate scale inhibitor as well as preparation method and application thereof in water treatment

Abstract

The invention discloses a calcium sulfate scale inhibitor as well as a preparation method and application thereof in water treatment, and belongs to the technical field of water treatment. Acrylic acid and chloropropene are used as monomers of the calcium sulfate scale inhibitor, free radical aqueous solution polymerization is performed under the action of an initiator and a reducing agent to obtain the calcium sulfate scale inhibitor, the mass ratio of the acrylic acid to the chloropropene is (4-19): 1, and the viscosity average molecular weight of the calcium sulfate scale inhibitor is 2900-10000. The water-soluble copolymer is prepared by adopting an aqueous solution free radical polymerization method, the synthesis process is simple, the use cost is low, and the obtained copolymer has good hydrophobic effect and calcium sulfate inhibition capability and can effectively solve the problem of scaling of calcium sulfate in a circulating cooling water system. The calcium sulfate scale inhibitor is good in dispersity, does not contain phosphorus, can greatly reduce emission of phosphorus in circulating cooling water, avoids secondary pollution to a water body, and is environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a calcium sulfate scale inhibitor, a preparation method thereof and application in water treatment. Background Art

[0002] In industrial production, circulating cooling water will be seriously scaled during long-term use. One of the more common scaling components is calcium sulfate. These scaling deposits will seriously reduce the conveying capacity and heat conduction efficiency of the pipeline system, and even corrode the pipeline. This not only causes a waste of funds, but also increases production risks. At present, the most effective way to alleviate scaling in industrial water treatment is to add scale inhibitors to the water body. Scale inhibitors can effectively inhibit the precipitation of scale-forming ions in water, and at the same time disperse the formed scale in the water to prevent the formation of hard scale on the surface of the equipment. However, the abuse of phosphorus-containing scale inhibitors has caused serious water pollution. At present, water treatment agents have been developed and developed in the direction of green and phosphorus-free to achieve environmentally friendly and green development. However, common scale inhibitors have a large dosage, which will also aggravate environmental pollution, and a small dosage cannot achieve the ideal scale inhibition effect. For example, PAA, the scale inhibition rate of calcium sulfate at a dosage of 6ppm is only 48.52%, and the dosage of 10ppm is effective for calcium sulfate scale inhibition. Therefore, the production and use of "green and environmentally friendly" scale inhibitors with significant effects and no pollution has become a top priority in scale research. Summary of the invention

[0003] In view of the problems that calcium sulfate scale inhibitors in the prior art have poor scale inhibition effect and cause great environmental pollution, the present invention provides a calcium sulfate scale inhibitor and a preparation method thereof and application in water treatment. The prepared calcium sulfate scale inhibitor has good calcium sulfate scale inhibition performance and can effectively solve the scaling problem in a circulating cooling water system. The scale inhibitor has a simple preparation process, a small amount of monomer residue, a high conversion rate, a relatively low synthesis cost, is easy to promote, and has good application prospects.

[0004] The present invention is achieved through the following technical solutions: A calcium sulfate scale inhibitor is provided. Acrylic acid and allyl chloride are used as monomers. The calcium sulfate scale inhibitor is obtained by free radical aqueous solution polymerization under the action of an initiator and a reducing agent. The mass ratio of acrylic acid to allyl chloride is 4-19:1. The viscosity average molecular weight of the calcium sulfate scale inhibitor is 2900-10000.

[0005] Furthermore, the initiator is sodium persulfate; and the reducing agent is sodium bisulfite.

[0006] Furthermore, the initiator is 1.3-1.6% of the monomer mass; the reducing agent is 8-10% of the monomer mass.

[0007] Furthermore, the mass ratio of acrylic acid to allyl chloride is 19:1.

[0008] In the present invention, the preparation method of the calcium sulfate scale inhibitor comprises the following steps: (1) dissolving allyl chloride in acrylic acid to obtain a mixture of acrylic acid and allyl chloride; (2) Add a certain amount of water into the reaction container, heat it to 80-85°C, and simultaneously dropwise add the acrylic acid and allyl chloride mixture, the initiator aqueous solution and the reducing agent aqueous solution in step (1). After the dropwise addition is completed, keep the temperature for reaction for 30-60 minutes. After the reaction is completed, cool it to room temperature to obtain a calcium sulfate scale inhibitor.

[0009] Furthermore, in step (2), the mass percentage concentration of the initiator aqueous solution is 13%; the mass percentage concentration of the reducing agent aqueous solution is 25%.

[0010] Furthermore, in step (1), the amount of water added to the reaction vessel is 1 to 1.3 times the mass of the mixture of acrylic acid and allyl chloride.

[0011] Furthermore, in step (2), the dripping time of the mixture of acrylic acid and allyl chloride is 60 minutes; the initiator aqueous solution and the reducing agent aqueous solution are dripped 2 to 3 minutes before the mixture of acrylic acid and allyl chloride, and are continued to be dripped for 1 to 6 minutes after the dripping of the mixture of acrylic acid and allyl chloride is completed. The total dripping time of the initiator aqueous solution and the reducing agent aqueous solution is 63 to 68 minutes.

[0012] Furthermore, the heat preservation reaction time in step (2) is 40 minutes.

[0013] In the present invention, the application of the calcium sulfate scale inhibitor in water treatment is characterized in that it is used for the treatment of calcium sulfate in water. Beneficial Effects

[0014] (1) The present invention uses acrylic acid and propylene chloride as raw materials and adopts an aqueous solution free radical polymerization method to prepare a water-soluble copolymer. The synthesis process is simple and the use cost is low. The obtained copolymer has good hydrophobic effect and calcium sulfate resistance, and can effectively solve the scaling problem of calcium sulfate in the circulating cooling water system; (2) The calcium sulfate scale inhibitor in the present invention has stable performance, low usage concentration, excellent calcium sulfate scale inhibition performance, and has chelation, dispersion, lattice distortion and other effects on calcium sulfate scale, and can effectively inhibit the formation of scale. When the scale inhibitor obtained by the present invention is added at a dosage of 6ppm, the scale inhibition rate of calcium sulfate is as high as 98.31%, and when the dosage is 5ppm, the scale inhibition rate can reach 60.34%; while when the PAA polymer is added at a dosage of 6ppm, the scale inhibition rate of calcium sulfate is only 48.52%, and when the dosage is 5ppm, the scale inhibition rate of calcium sulfate is 32.3%; (3) The calcium sulfate scale inhibitor in the present invention has good dispersibility and does not contain phosphorus, which can greatly reduce the discharge of phosphorus in circulating cooling water, avoid secondary pollution to the water body, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the NMR carbon spectrum of the calcium sulfate scale inhibitor prepared in Example 1; Figure 2 This is the H NMR spectrum of the calcium sulfate scale inhibitor prepared in Example 1; Figure 3 This is the NMR carbon spectrum of the calcium sulfate scale inhibitor prepared in Example 2; Figure 4 This is the H NMR spectrum of the calcium sulfate scale inhibitor prepared in Example 2; Figure 5 This is the NMR carbon spectrum of the calcium sulfate scale inhibitor prepared in Example 3; Figure 6 This is the H NMR spectrum of the calcium sulfate scale inhibitor prepared in Example 3; Figure 7 This is the NMR carbon spectrum of the calcium sulfate scale inhibitor prepared in Example 4; Figure 8 This is the H NMR spectrum of the calcium sulfate scale inhibitor prepared in Example 4. DETAILED DESCRIPTION

[0016] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0017] The monomer acrylic acid, initiator sodium persulfate, reducing agent sodium bisulfite and polyacrylic acid PAA (light yellow transparent liquid, content of 50%) used in the present invention are all from Shandong Taihe Water Treatment Technology Co., Ltd.; allyl chloride is from Shanghai MacLean Biochemical Technology Co., Ltd. The content of acrylic acid is 99.8%, and the content of allyl chloride is 98%. Example 1

[0018] (1) Weigh 185.0 g of deionized water into a four-necked flask and heat it to 83°C; (2) Weigh 7.92 g of monomer allyl chloride and dissolve it in 150 g of acrylic acid to obtain a mixture of acrylic acid and allyl chloride; dissolve 3.0 g of initiator sodium persulfate in water to obtain an initiator aqueous solution (mass percentage concentration 13%); dissolve 18 g of reducing agent sodium bisulfite in water to obtain a reducing agent aqueous solution (mass percentage concentration 25%); add the mixture of acrylic acid and allyl chloride, the initiator aqueous solution, and the reducing agent aqueous solution dropwise by a peristaltic pump, the acrylic acid and allyl chloride mixture dropwise for 60 min, the initiator aqueous solution and the reducing agent aqueous solution dropwise at the same time and 2 min in advance of the monomer, continue to dropwise for 1 min after the acrylic acid and allyl chloride mixture is added, and the total dropwise addition time is 63 min, the initiator aqueous solution and the reducing agent aqueous solution are added dropwise at the same time, and the temperature is controlled at 83±2°C during the dropwise addition process; (3) After the addition of the initiator aqueous solution and the reducing agent aqueous solution is completed, the reaction is kept warm for 40 minutes. After the reaction is completed, the temperature is lowered and the material is discharged to obtain a white viscous transparent liquid, which is an acrylic acid / propylene chloride copolymer, that is, a calcium sulfate scale inhibitor. The viscosity average molecular weight of the obtained product is 2996.

[0019] The nuclear magnetic carbon spectrum and nuclear magnetic hydrogen spectrum of the calcium sulfate scale inhibitor prepared in this example are as follows: Figure 1 , Figure 2 shown. Example 2

[0020] (1) Weigh 185.0 g of deionized water into a four-necked flask and heat it to 83°C; (2) Weigh 15.79 g of monomer allyl chloride and dissolve it in 142.11 g of acrylic acid to obtain a mixture of acrylic acid and allyl chloride. Dissolve 3.0 g of initiator sodium persulfate in water to obtain an initiator aqueous solution (mass percentage concentration 13%). Dissolve 18 g of reducing agent sodium bisulfite in water to obtain a reducing agent aqueous solution (mass percentage concentration 25%). Use a peristaltic pump to drop the mixture of acrylic acid and allyl chloride, the initiator aqueous solution, and the reducing agent aqueous solution. The monomer is added for 61 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added simultaneously and 2 minutes in advance of the acrylic acid and allyl chloride mixture. After the acrylic acid and allyl chloride mixture is added, the addition is continued for 5 minutes until the addition is complete. The total addition time is 68 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added simultaneously. During the addition, the temperature is controlled at 83±2°C. (3) After the addition of the initiator aqueous solution and the reducing agent aqueous solution is completed, the reaction is kept warm for 40 minutes. After the reaction is completed, the temperature is lowered and the material is discharged to obtain a yellow viscous transparent liquid, which is an acrylic acid / propylene chloride copolymer, that is, a calcium sulfate scale inhibitor. The viscosity average molecular weight of the obtained product is 4492.

[0021] The nuclear magnetic carbon spectrum and nuclear magnetic hydrogen spectrum of the calcium sulfate scale inhibitor prepared in this example are as follows: Figure 3 , Figure 4 shown. Example 3

[0022] (1) Weigh 185.0 g of deionized water into a four-necked flask and heat it to 83°C; (2) Weigh 23.68 g of monomer allyl chloride and dissolve it in 134.25 g of acrylic acid to obtain a mixture of acrylic acid and allyl chloride. Dissolve 3.0 g of initiator sodium persulfate in water to obtain an initiator aqueous solution (mass percentage concentration 13%). Dissolve 18 g of reducing agent sodium bisulfite in water to obtain a reducing agent aqueous solution (mass percentage concentration 25%). Use a peristaltic pump to drop the mixture of acrylic acid and allyl chloride, the initiator aqueous solution, and the reducing agent aqueous solution. The acrylic acid and allyl chloride mixture is added dropwise for 62 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added dropwise at the same time and 2 minutes before the acrylic acid and allyl chloride mixture is added dropwise. After the acrylic acid and allyl chloride mixture is added dropwise, the addition is continued for 4 minutes until the addition is complete. The total addition time is 68 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added dropwise at the same time. During the addition, the temperature is controlled at 83±2°C. (3) After the addition of the initiator aqueous solution and the reducing agent aqueous solution is completed, the reaction is kept warm for 40 minutes. After the reaction is completed, the temperature is lowered and the material is discharged to obtain a yellow viscous transparent liquid, which is an acrylic acid / propylene chloride copolymer, that is, a calcium sulfate scale inhibitor. The viscosity average molecular weight of the obtained product is 4723.

[0023] The nuclear magnetic carbon spectrum and nuclear magnetic hydrogen spectrum of the calcium sulfate scale inhibitor prepared in this example are as follows: Figure 5 , Figure 6 shown. Example 4

[0024] (1) Weigh 185.0 g of deionized water into a four-necked flask and heat it to 83°C; (2) Weigh 31.58 g of monomer allyl chloride and dissolve it in 126.32 g of acrylic acid to obtain a mixture of acrylic acid and allyl chloride. Dissolve 3.0 g of initiator sodium persulfate in water to obtain an initiator aqueous solution (mass percentage concentration 13%). Dissolve 18 g of reducing agent sodium bisulfite in water to obtain a reducing agent aqueous solution (mass percentage concentration 25%). Use a peristaltic pump to drop the mixture of acrylic acid and allyl chloride, the initiator aqueous solution, and the reducing agent aqueous solution. The acrylic acid and allyl chloride mixture is added dropwise for 62 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added dropwise at the same time and 2 minutes before the acrylic acid and allyl chloride mixture is added dropwise. After the acrylic acid and allyl chloride mixture is added dropwise, the addition is continued for 3 minutes until the addition is complete. The total addition time is 67 minutes. The initiator aqueous solution and the reducing agent aqueous solution are added dropwise at the same time. During the addition, the temperature is controlled at 83±2°C. (3) After the addition of the initiator aqueous solution and the reducing agent aqueous solution is completed, the reaction is kept warm for 40 minutes. After the reaction is completed, the temperature is lowered and the material is discharged to obtain a yellow viscous transparent liquid, which is an acrylic acid / propylene chloride copolymer, that is, a calcium sulfate scale inhibitor. The viscosity average molecular weight of the obtained product is 9046.

[0025] The nuclear magnetic carbon spectrum and nuclear magnetic hydrogen spectrum of the calcium sulfate scale inhibitor prepared in this example are as follows: Figure 7 , Figure 8 shown.

[0026] The calcium sulfate scale inhibitor and polyacrylic acid PAA prepared in the example were used to measure the scale inhibition performance of calcium sulfate according to the industry standard Q / SY 126-2014 "Technical Specifications for Corrosion and Scale Inhibitors for Oilfield Water Treatment". The results are shown in Table 1.

[0027] Table 1 Calcium sulfate scale inhibition rate of different concentrations of scale inhibitors .

Claims

1. A calcium sulfate scale inhibitor, characterized in that: With acrylic acid and allyl chloride as monomers, free radical aqueous solution polymerization is carried out under the action of an initiator and a reducing agent to obtain a calcium sulfate scale inhibitor, the mass ratio of acrylic acid to allyl chloride is 4-19:1, and the viscosity-average molecular weight of the calcium sulfate scale inhibitor is 2900-10000.

2. The calcium sulfate scale inhibitor according to claim 1, characterized in that The initiator is sodium persulfate; the reducing agent is sodium bisulfite.

3. The calcium sulfate scale inhibitor according to claim 1, characterized in that The initiator is 1.3-1.6% of the monomer mass; the reducing agent is 8-10% of the monomer mass.

4. The calcium sulfate scale inhibitor according to claim 1, characterized in that: The mass ratio of acrylic acid to allyl chloride is 19:

1.

5. A method for preparing the calcium sulfate scale inhibitor according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) dissolving allyl chloride in acrylic acid to obtain a mixture of acrylic acid and allyl chloride; (2) Add a certain amount of water into the reaction container, heat it to 80-85°C, and simultaneously dropwise add the acrylic acid and allyl chloride mixture, the initiator aqueous solution and the reducing agent aqueous solution in step (1). After the dropwise addition is completed, keep the temperature for reaction for 30-60 minutes. After the reaction is completed, cool it to room temperature to obtain a calcium sulfate scale inhibitor.

6. The method for preparing the calcium sulfate scale inhibitor according to claim 5, characterized in that: In step (2), the mass percentage concentration of the initiator aqueous solution is 13%; the mass percentage concentration of the reducing agent aqueous solution is 25%.

7. The method for preparing a calcium sulfate scale inhibitor according to claim 5, characterized in that: In step (1), the amount of water added to the reaction container is 1 to 1.3 times the mass of the mixture of acrylic acid and allyl chloride.

8. The method for preparing a calcium sulfate scale inhibitor according to claim 5, characterized in that: In step (2), the dripping time of the mixture of acrylic acid and allyl chloride is 60 minutes; the initiator aqueous solution and the reducing agent aqueous solution are dripped 2 to 3 minutes before the mixture of acrylic acid and allyl chloride, and are continued to be dripped for 1 to 6 minutes after the dripping of the mixture of acrylic acid and allyl chloride is completed. The total dripping time of the initiator aqueous solution and the reducing agent aqueous solution is 63 to 68 minutes.

9. The method for preparing a calcium sulfate scale inhibitor according to claim 5, characterized in that: The heat preservation reaction time in step (2) is 40 minutes.

10. Use of the calcium sulfate scale inhibitor according to any one of claims 1 to 4 in water treatment, characterized in that: Used for the treatment of calcium sulfate in water.

Images