CN118684821A - A scale inhibitor for sewage treatment and its preparation method and application - Google Patents

Abstract

The present invention belongs to the technical field of sewage treatment, and specifically relates to a scale inhibitor for sewage treatment, and its preparation method and application. The preparation method is as follows: add butenedioic acid, 2-acrylamide-2-methylpropanesulfonic acid, 1-vinyl-3-ethylimidazolium bromide, (2-acrylamideethyl)phosphonic acid, dipotassium hydrogen phosphate, deionized water in the reactor in sequence, deoxygenate, stir, and adjust pH7-8; add initiator to the reactor, add dropwise, continue stirring, the mixed solution automatically heats up, and after the temperature stabilizes, continue stirring for 30-60min, then heat up to 60-65℃, continue stirring for 60-80min, adjust pH6-7, cool to below 40℃, and obtain a viscous liquid; add ethanol to the above-mentioned viscous liquid to precipitate solids, filter, dry overnight, and obtain a product scale inhibitor. The scale inhibitor of the present invention has the advantages of simple preparation method and good scale inhibition effect.

Description

A scale inhibitor for sewage treatment and its preparation method and application

Technical Field

The invention belongs to the technical field of sewage treatment, and specifically relates to a scale inhibitor for sewage treatment and a preparation method and application thereof.

Background Art

Water is the source of life, a necessary living material for human beings, and an indispensable raw material and energy carrier in production activities. With the development of society, water shortage and pollution are becoming increasingly serious, people's environmental awareness is increasing, and the industrialization process is accelerating. Circulating cooling water accounts for a large proportion of industrial water. Circulating cooling water is prone to produce inorganic calcium scale after repeated use, such as calcium carbonate, calcium sulfate, barium sulfate, etc. These calcium scales adhere to the inner surface of the pipeline, which will greatly reduce the cooling efficiency of circulating cooling water and bring great disadvantages to industrial production. Therefore, it is urgent to improve the recycling rate of water.

In order to reduce the adverse effects of scale, researchers have studied chemical and physical methods to solve the above problems. Physical treatment methods mainly include electrolysis, electric field, ultrasonic method, etc. This type of method is low-cost and has no secondary pollution, but requires regular shutdown maintenance and complex operation. Generally, it can only treat water with lower hardness and is not suitable for industrial circulating cooling water treatment with complex scale components. Chemical methods include acidification, lime treatment and scale inhibitor treatment. This type of method has the advantages of simple equipment and a wide range of applicable water quality, but the acidification and lime treatment methods have the disadvantages of large acid consumption and high treatment costs, and bring about an increase in ionic strength, which is not conducive to the application of certain industrial scenarios. The use of scale inhibitor treatment has become an important scale inhibition method in industry. Its principle is generally to use the coordination groups of scale inhibitors and metal ions to produce chelation, solubilization and adsorption with calcium and magnesium ions during cooling water treatment. The scale inhibitor treatment method has simple dosing equipment; convenient operation and maintenance, and scale inhibition and dispersion. Therefore, adding scale inhibitors is currently the most popular and reliable method.

CN105254039A discloses a solid corrosion-inhibiting and antiscaling agent for oil fields and a preparation method thereof, and belongs to the technical field of petroleum additives. The oil field is prepared by a series of steps using Echinacea extract, Perilla, Arsanilic acid, Artemisinin, Tartaric acid, 2-hydroxyl tetradecanoic acid, sorbitol, hydroxystearin, sodium acryloyldimethyltaurate, sulfosuccinate, dehydroabietic acid, ethanol and water as raw materials. The prepared antiscaling agent has the advantages of long effective protection period of the agent, less waste of the agent, and good corrosion and antiscaling effect. According to experimental determination, the corrosion inhibition rate is ≥92% and the scale inhibition rate is ≥95%. The preparation method of the invention is simple, the raw materials are phosphorus-free, and it is environmentally friendly. The prepared solid corrosion-inhibiting and antiscaling agent for oil fields has good dispersing and antiscaling effects, and is easy to promote and apply. However, the raw materials of the invention are too complicated, the production cost is high, and it is difficult to promote and use on a large scale.

CN106380535A discloses an oilfield scale inhibitor and its preparation method, belonging to the field of chemical materials. In terms of weight percentage, it is made of the following components: 10-30% dimethyl maleic anhydride polymerization monomer; 10-30% sodium allyl sulfonate polymerization monomer; 10-30% methacrylic acid three polymerization monomers; 5-20% emulsifier; 2-10% initiator; 10-30% organic solvent; 1-5% chain transfer agent; 10-25% deionized water. The scale inhibitor is formed by copolymerizing the three monomers of dimethyl maleic anhydride, sodium allyl sulfonate and methacrylic acid in an organic solvent, and does not contain phosphorus substances; the scale inhibitor has a simple synthesis process, mild reaction conditions, and the synthesized copolymer has strong scale inhibition ability and high purity, and can achieve good scale inhibition effect with a small amount. A large amount of organic solvents are required in the synthesis process of the scale inhibitor of the invention, and these organic solvents are highly toxic and pose a great threat to the safety of production operators.

Summary of the invention

The present invention aims at the above-mentioned deficiencies of the prior art and provides a scale inhibitor for sewage treatment and its preparation method and application. The scale inhibitor of the present invention has the advantages of simple preparation method and good scale inhibition effect.

In order to achieve the above objectives:

One of the purposes of the present invention is to disclose a method for preparing a scale inhibitor for sewage treatment, the specific steps of which are as follows:

(1) adding butenedioic acid, 2-acrylamido-2-methylpropanesulfonic acid, 1-vinyl-3-ethylimidazolium bromide, (2-acrylamidoethyl)phosphonic acid, dipotassium hydrogen phosphate, and deionized water into a reactor in sequence, purging with nitrogen to remove oxygen, stirring, and adjusting the pH to 7-8 with sodium hydroxide solution;

(2) adding an initiator dropwise to the reactor, continuing to stir after the addition is complete, the mixed solution automatically heats up, and after the temperature stabilizes, continuing to stir for 30-60 minutes, then heating to 60-65° C., continuing to stir for 60-80 minutes, adjusting the pH to 6-7 with a sodium hydroxide solution, and cooling to below 40° C. to obtain a viscous liquid;

(3) Add ethanol to the above viscous liquid to precipitate solids, filter, and dry at 70° C. overnight to obtain a scale inhibitor product.

In the present invention, preferably, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid, 1-vinyl-3-ethylimidazolium bromide, (2-acrylamidoethyl)phosphonic acid to butenedioic acid is 0.2-0.4:0.2-0.4:0.05-0.1:1.

In the present invention, preferably, in step (1), the weight ratio of dipotassium hydrogen phosphate, deionized water and maleic acid is 0.1-0.2:8-10:1.

In the present invention, preferably, in step (2), the initiator is a mixed solution of persulfate and sodium bisulfite, and the weight ratio of the initiator to butenedioic acid is 0.1-0.3:1.

Preferably, the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.

Preferably, the concentration of the persulfate is 10-12 wt %, and the concentration of the sodium bisulfite is 3-5 wt %.

In the present invention, preferably, in step (3), the weight ratio of ethanol to butenedioic acid is 15-20:1.

The synthetic reaction equation of the main product of the scale inhibitor for sewage treatment of the present invention is as follows:

Another object of the present invention is to disclose a scale inhibitor prepared by the above preparation method, wherein the main product molecular structure of the scale inhibitor is as follows:

Where: a = 1000-10000;

b = 200-4000;

c = 200-4000;

d＝50-1000.

Preferably, the viscosity average molecular weight of the main product of the antiscalant is 200,000-1,000,000.

The third object of the present invention is to disclose the application of the above-mentioned scale inhibitor in sewage treatment.

The scale inhibitor for sewage treatment of the present invention is a tetrapolymer formed by polymerization of butenedioic acid, 2-acrylamido-2-methylpropanesulfonic acid, 1-vinyl-3-ethylimidazolium bromide, and (2-acrylamidoethyl)phosphonic acid, and contains functional groups such as carboxylic acid, amide, sulfonic acid, imidazoline, and phosphoric acid, all of which have chelating effects, can reduce the free concentration of high-valent metal ions in water, and slow down the contact probability of high-valent ions with carbonate and sulfate, thereby playing a scale inhibitory role. The chain structure of the present invention can adsorb multiple microcrystals of the same charge, and the electrostatic repulsion between them can prevent the mutual collision of microcrystals, thereby avoiding the formation of large crystals. During the scale growth process, the present invention is adsorbed in the crystal growth lattice, which will change the normal shape of the crystal and hinder its growth into larger crystals. Since the scale inhibitor dispersant molecules are adsorbed in the lattice, the regularity of the crystal is greatly destroyed, and the crystal lattice of the crystal is deformed, resulting in a decrease in the strength of the scale crystal, becoming loose and easily washed by water flow, so that the scale is peeled off from the heat transfer surface.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The scale inhibitor for sewage treatment of the present invention has low cost, simple preparation method, convenient use and small dosage;

(2) The scale inhibitor for sewage treatment of the present invention has a good scale inhibition effect. When the concentration is 6 mg/L, the scale inhibition rate can reach 98%.

DETAILED DESCRIPTION

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

The technical solution of the invention is further described below in conjunction with specific embodiments:

Example 1

(1) 0.2 mol of butenedioic acid, 0.04 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.07 mol of 1-vinyl-3-ethylimidazolium bromide, 0.01 mol of (2-acrylamidoethyl)phosphonic acid, 2.32 g of dipotassium hydrogen phosphate, and 185.6 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 2.32 g of an initiator containing 12 wt % potassium persulfate and 5 wt % sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 30 min. The temperature was then raised to 60° C. and stirring was continued for 60 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 348 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 2

(1) 0.2 mol of butenedioic acid, 0.05 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.08 mol of 1-vinyl-3-ethylimidazolium bromide, 0.012 mol of (2-acrylamidoethyl)phosphonic acid, 2.84 g of dipotassium hydrogen phosphate, and 232 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 3.18 g of an initiator containing 12 wt % potassium persulfate and 5 wt % sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 40 min. The temperature was then raised to 65° C. and stirring was continued for 60 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 464 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 3

(1) 0.2 mol of butenedioic acid, 0.055 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.075 mol of 1-vinyl-3-ethylimidazolium bromide, 0.014 mol of (2-acrylamidoethyl)phosphonic acid, 2.92 g of dipotassium hydrogen phosphate, and 224 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 4.22 g of an initiator containing 11 wt % potassium persulfate and 4 wt % sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 60 min. The temperature was then raised to 60° C. and stirring was continued for 70 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) Add 460 g of ethanol to the above viscous liquid to precipitate the solid, filter it, and dry it at 70° C. overnight to obtain a scale inhibitor product.

Example 4

(1) 0.2 mol of butenedioic acid, 0.06 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.065 mol of 1-vinyl-3-ethylimidazolium bromide, 0.016 mol of (2-acrylamidoethyl)phosphonic acid, 3.42 g of dipotassium hydrogen phosphate, and 216 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 6.96 g of an initiator containing 10 wt % potassium persulfate and 3 wt % sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 50 min. The temperature was then raised to 62° C. and stirring was continued for 60 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 448 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 5

(1) 0.2 mol of butenedioic acid, 0.065 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.07 mol of 1-vinyl-3-ethylimidazolium bromide, 0.015 mol of (2-acrylamidoethyl)phosphonic acid, 4.64 g of dipotassium hydrogen phosphate, and 200 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 5.14 g of an initiator containing 11 wt % of sodium persulfate and 4 wt % of sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 30 min. The temperature was then raised to 65° C. and stirring was continued for 80 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) Add 400 g of ethanol to the above viscous liquid to precipitate the solid, filter it, and dry it at 70° C. overnight to obtain a scale inhibitor product.

Example 6

(1) 0.2 mol of butenedioic acid, 0.07 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.055 mol of 1-vinyl-3-ethylimidazolium bromide, 0.018 mol of (2-acrylamidoethyl)phosphonic acid, 3.88 g of dipotassium hydrogen phosphate, and 195 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 6.11 g of an initiator containing 10 wt % of sodium persulfate and 3 wt % of sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 45 min. The temperature was then raised to 63° C. and stirring was continued for 65 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 358 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 7

(1) 0.2 mol of butenedioic acid, 0.075 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.045 mol of 1-vinyl-3-ethylimidazolium bromide, 0.019 mol of (2-acrylamidoethyl)phosphonic acid, 4.12 g of dipotassium hydrogen phosphate, and 202 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 5.16 g of an initiator containing 10 wt % of ammonium persulfate and 3 wt % of sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 50 min. The temperature was then raised to 65° C. and stirring was continued for 75 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 372 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 8

(1) 0.2 mol of butenedioic acid, 0.08 mol of 2-acrylamido-2-methylpropanesulfonic acid, 0.04 mol of 1-vinyl-3-ethylimidazolium bromide, 0.02 mol of (2-acrylamidoethyl)phosphonic acid, 3.92 g of dipotassium hydrogen phosphate, and 211 g of deionized water were added to a reactor in sequence, and nitrogen was purged to remove oxygen. The mixture was stirred and the pH was adjusted to 7-8 with sodium hydroxide solution.

(2) 5.32 g of an initiator containing 11 wt % of ammonium persulfate and 5 wt % of sodium bisulfite was added dropwise to the reactor. After the addition was completed, stirring was continued. The mixed solution automatically heated up. After the temperature stabilized, stirring was continued for 60 min. The temperature was then raised to 60° C. and stirring was continued for 60 min. The pH was adjusted to 6-7 with sodium hydroxide solution and the temperature was lowered to below 40° C. to obtain a viscous liquid.

(3) The above viscous liquid was added with 392 g of ethanol to precipitate the solid, which was filtered and dried at 70° C. overnight to obtain a scale inhibitor product.

Example 9 Evaluation of scale inhibition effect

The scale inhibitors (Examples 1-8) of the present invention were evaluated. The evaluation method was based on GB/T16632-2019 "Determination of scale inhibition performance of water treatment agents - calcium carbonate deposition method". The dosage of the scale inhibitor was 2, 4, and 6 mg/L. The object of evaluation was reverse osmosis influent from a water treatment company. ATMP (aminotri(methylenephosphonic acid)) was used as a comparison sample. The test results are shown in Table 1.

Table 1 Scale inhibition rate determination results (%)

From Table 1 we can see that:

(1) The scale inhibition rate of the scale inhibitor for sewage treatment of the present invention reaches more than 91% when the concentration is 2 mg/L, and the highest is 93.2%; while the scale inhibition rate of ATMP (aminotrimethylenephosphonic acid) in the comparative example is 69.8%, which is significantly lower than that of the present invention;

(2) The scale inhibition rate of the scale inhibitor for sewage treatment of the present invention reaches 96% or more when the concentration is 4 mg/L, and the highest is 97.3%; while the scale inhibition rate of ATMP (aminotrimethylenephosphonic acid) in the comparative example is 85.3%, which is significantly lower than that of the present invention;

(3) The scale inhibition rate of the scale inhibitor for sewage treatment of the present invention reaches 98% or above when the usage concentration is 6 mg/L, with the highest reaching 98.4%; while the scale inhibition rate of the comparative example ATMP (aminotri(methylenephosphonic acid)) is 90.6%, which is significantly lower than that of the present invention.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (8)

1. The preparation method of the scale inhibitor for sewage treatment is characterized by comprising the following specific steps of:

(1) Sequentially adding butenedioic acid, 2-acrylamido-2-methylpropanesulfonic acid, 1-vinyl-3-ethylimidazole bromide, (2-acrylamidoethyl) phosphonic acid, dipotassium hydrogen phosphate and deionized water into a reactor, purging with nitrogen to remove oxygen, stirring, and regulating the pH to 7-8 with sodium hydroxide solution;

(2) Dropwise adding an initiator into the reactor, continuously stirring after the dropwise adding is finished, automatically heating the mixed solution, continuously stirring for 30-60min after the temperature is stable, then heating to 60-65 ℃, continuously stirring for 60-80min, regulating the pH value to 6-7 by using a sodium hydroxide solution, and cooling to below 40 ℃ to obtain a viscous liquid;

(3) And adding ethanol into the viscous liquid to settle out solid, filtering, and drying at 70 ℃ overnight to obtain the product scale inhibitor.

2. The method for preparing the scale inhibitor for sewage treatment according to claim 1, wherein the molar ratio of the 2-acrylamido-2-methylpropanesulfonic acid, the 1-vinyl-3-ethylimidazole bromide and the (2-acrylamidoethyl) phosphonic acid to the butenedioic acid is 0.2-0.4:0.2-0.4:0.05-0.1:1.

3. The method for preparing a scale inhibitor for sewage treatment according to claim 1, wherein in the step (1), the weight ratio of dipotassium hydrogen phosphate, deionized water and butenedioic acid is 0.1-0.2:8-10:1.

4. The method for preparing a scale inhibitor for sewage treatment according to claim 1, wherein in the step (2), the initiator is a mixed solution of persulfate and sodium bisulfite, and the weight ratio of the initiator to the butenedioic acid is 0.1-0.3:1.

5. The method for preparing a scale inhibitor for sewage treatment according to claim 4, wherein the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.

6. The method for preparing a scale inhibitor for sewage treatment according to claim 4, wherein the concentration of the persulfate is 10-12wt% and the concentration of the sodium bisulphite is 3-5wt%.

7. The scale inhibitor prepared by the preparation method according to any one of claims 1 to 6.

8. The use of the scale inhibitor according to claim 7 in sewage treatment.