A phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system

Abstract

The present invention belongs to the technical field of scale inhibitors for reverse osmosis systems, and discloses a scale inhibitor used in a high-salt and high-alkali water desalination reverse osmosis system. The scale inhibitor prepared by the present invention is composed of brown algae extract, sodium alginate, deionized water, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, etc. The present invention adopts environmentally friendly components, does not contain any organic phosphine or inorganic phosphate, is easily biodegradable, can not only reduce the risk of microbial contamination of the membrane system, but also reduces the impact of sewage discharge on the environment. Compared with traditional scale inhibitors, the scale inhibition performance is superior and the scale inhibition range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of scale inhibitors for reverse osmosis systems, and in particular to a scale inhibitor used in a reverse osmosis system for desalination of high-salt and high-alkali water. Background Art

[0002] In recent years, reverse osmosis and ion exchange have been widely used in water treatment. Reverse osmosis has gradually replaced ion exchange and become the main technology for pure water preparation due to its advantages of small footprint, low operating costs, no secondary pollution, stable water output, and high degree of automation. In particular, reverse osmosis technology plays a key role in the desalination of saline-alkali water. However, due to the high salt and alkalinity characteristics of saline-alkali water, it is easy to cause scaling on some reverse osmosis membranes and membrane tubes used. Membrane scaling will lead to a decrease in membrane filtration performance and more frequent membrane cleaning or replacement, which will eventually reduce water production and increase costs. In severe cases, it will also affect the normal and stable operation of the system. Adding scale inhibitors is an important means to prevent scaling.

[0003] Scale inhibitors are agents that prevent or interfere with the precipitation and scaling of insoluble inorganic salts on metal surfaces. They are often used in reverse osmosis water treatment systems to prevent scale from being deposited on reverse osmosis membranes. According to their chemical composition, scale inhibitors can generally be divided into phosphorus-based scale inhibitors and synthetic polymer scale inhibitors. The use of phosphorus-containing scale inhibitors will increase the phosphorus content in the water body, accelerate the growth of microorganisms in the water, and long-term accumulation will also pollute water resources and endanger human health, thus causing water pollution. Synthetic polymer scale inhibitors have problems such as difficulty in degradation after use. With the requirements of sustainable development and environmental protection, phosphorus-free, non-toxic green scale inhibitors have become a research hotspot in the water treatment agent industry. Summary of the invention

[0004] In view of this, in order to solve the technical problems of the existing traditional phosphorus-containing scale inhibitors such as large usage, non-biodegradability, and pollution to the environmental water bodies, the present invention provides a green and environmentally friendly phosphorus-free scale inhibitor suitable for use in high-salt and high-alkali water desalination and alkali reverse osmosis systems. The scale inhibitor has high efficiency in scale inhibition and is very friendly to the ecological environment.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system consists of brown algae extract, sodium alginate, deionized water, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, carboxymethyl dextran and attapulgite.

[0007] In a further technical solution of the present invention, the weight proportions of the phosphorus-free scale inhibitor components suitable for saline-alkali water reverse osmosis system are as follows: 1-3 parts of brown algae extract, 3-11 parts of sodium alginate, 40-80 parts of deionized water, 6-10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2-7 parts of carboxymethyl dextran, and 2-10 parts of attapulgite.

[0008] In a further technical solution of the present invention, the preferred brown algae extract is Sargassum extract.

[0009] The saline-alkali water used in the present invention is saline-alkali water with a salt content of 1000-5000 mg / L and an alkalinity of 200-400 mg / L (calcium carbonate).

[0010] When the phosphorus-free scale inhibitor prepared by the invention is used to treat high-salt and high-alkali water by using a reverse osmosis membrane system, the concentration of the phosphorus-free scale inhibitor added to the saline-alkali water is 4 mg / L.

[0011] In a further technical solution of the present invention, the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system specifically comprises the following steps:

[0012] ① Take brown algae extract, sodium alginate, deionized water, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, carboxymethyl dextran and attapulgite according to weight proportions for later use;

[0013] ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 30-35°C, then add brown algae extract, stir for 5-10 minutes, and continue to heat the reactor to 40-45°C;

[0014] ③ Then put the attapulgite into the reactor and stir for 5-10 minutes. Heat the reactor to 50-60°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor warm at 60°C and stir for 1.5-3 hours. Cool to room temperature to obtain the scale inhibitor.

[0015] It can be seen from the above technical solution that the present invention discloses a scale inhibitor used in a high-salt and high-alkali water desalination and alkali reverse osmosis system. Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The scale inhibitor prepared by the present invention does not contain any organic phosphine or inorganic phosphate, which can not only reduce the risk of microbial contamination of the membrane system, but also reduce the impact of sewage discharge on the environment.

[0017] 2. The scale inhibitor prepared by the present invention adopts environmentally friendly components, has excellent scale inhibition performance, is easily biodegradable, and solves the problem that traditional agents lack broad-spectrum scale inhibition performance for calcium carbonate, calcium sulfate, strontium carbonate and barium sulfate. After testing, the scale inhibition rate for calcium carbonate and calcium sulfate scale is above 90%.

[0018] 3. The present invention connects chitosan and allyl sulfonic acid to the commonly used carboxymethyl cellulose main chain through graft copolymerization, thereby introducing a large number of hydroxyl, amino and sulfonic acid groups, which not only solves the problem of poor water solubility of traditional cellulose, but also adds functional groups with good scale inhibition performance to the polymer chain, so that the prepared polymer can not only replace expensive components such as polyaspartic acid and polyepoxysuccinic acid in scale inhibitors, but also is easily biodegradable, environmentally friendly, and has quite superior scale inhibition performance.

[0019] 4. The scale inhibitor of the present invention also contains brown algae extract, which is rich in alginic acid. Alginic acid is the main component of brown algae and contains many functional sites in its molecules, such as hydroxyl and carboxylic acid groups. The carboxylic acid groups have great tolerance to cations in the solution or on the surface of inorganic minerals, and can seriously damage the crystal structure of calcium sulfate and calcium carbonate, thereby making them unable to adhere to the reverse osmosis membrane on the surface, thereby exerting scale inhibition performance.

[0020] 5. Sodium alginate is also added to the scale inhibitor of the present invention. When the scale inhibitor is added to sewage, the free calcium ions in the sewage will undergo a complex reaction with the sodium alginate, thereby interfering with the free calcium ions and carbonate ions to form precipitation, thereby exerting scale inhibition performance.

[0021] 6. The scale inhibition component of the present invention also includes attapulgite. Due to the special structure of attapulgite, it has adsorption and ion exchange effects. When added to high-salt and high-alkali sewage, it can adsorb a large number of anions and cations in the solution, reducing the number of various anions in the saline-alkali water. It not only reduces the salt content and alkalinity of the sewage, but also reduces the number of scale-forming ions from the source, and then assists the molecules in the scale inhibitor that exert scale inhibition performance to better react with the scale-forming ions in the solution, quickly exert the scale inhibition effect, and improve the scale inhibition efficiency of the scale inhibitor. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Unless otherwise specified, the operations and processing methods involved in the present invention are conventional operations in the art.

[0024] Unless otherwise specified, the instruments used in the present invention are conventional instruments in the art.

[0025] The embodiment of the present invention discloses a phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system. The phosphorus-free scale inhibitor is composed of brown algae extract, sodium alginate, deionized water, chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, carboxymethyl dextran, and attapulgite. The weight proportions of the components are as follows: 1-3 parts of brown algae extract, 3-11 parts of sodium alginate, 40-80 parts of deionized water, 6-10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2-10 parts of attapulgite, and 2-7 parts of carboxymethyl dextran. The typical but non-limiting contents of the brown algae extract are: 1 part, 1.5 parts, 2 parts, 2. a typical but non-limiting content of carboxymethyl dextran is 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts or 11 parts; a typical but non-limiting content of deionized water is 40 parts, 50 parts, 60 parts, 70 parts or 80 parts; a typical but non-limiting content of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer is 6 parts, 7 parts, 8 parts, 9 parts or 10 parts; a typical but non-limiting content of attapulgite is 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts; a typical but non-limiting content of carboxymethyl dextran is 2 parts, 3 parts, 4 parts, 5 parts, 6 parts or 7 parts.

[0026] In a specific embodiment of the present invention, the brown algae extract can be any one of kelp extract, wakame extract, giant kelp extract, water cloud extract, cord algae extract, acid algae extract, hemerocallis extract, cyst algae extract, rope algae extract, chickweed extract, net algae extract, round fan algae extract, sargassum extract, antler extract, sea wormwood extract, sea millet extract, and sea lettuce extract, or a mixture of any two or more in any proportion. Among them, the preparation method of the brown algae extract is specifically as follows: the brown algae is cleaned with distilled water, dried to constant weight in a constant temperature oven at 45°C, then crushed into coarse powder, mixed with distilled water at a weight ratio of 1:15, stirred and heated at 80°C for 6h, cooled to room temperature, vacuum filtered, and dried to obtain the brown algae extract.

[0027] According to a preferred embodiment of the present invention, the brown algae extract is a Sargassum extract.

[0028] In a further technical scheme of the present invention, the preparation method of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer is as follows: carboxymethyl cellulose is put into a reactor, distilled water is added to dissolve it, nitrogen is introduced for 30 minutes, the temperature of the reactor is raised to 70°C, stirring and reacting for 1 hour, chitosan and sodium allyl sulfonate are added and stirred evenly, the temperature of the reactor is lowered to 55°C, and an initiator is uniformly added dropwise, the mass of the initiator is 11% of the total mass of the monomers, and after the addition is completed, magnetic stirring is carried out at this temperature for 5 minutes, the temperature of the reactor is raised to 85°C, and the reaction is carried out for 3 hours, the reaction solution is mixed with acetone and allowed to stand until precipitation occurs, the acetone is recovered, the precipitate is washed with anhydrous ethanol, filtered under reduced pressure, and dried at 90°C to obtain chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer; wherein the molar ratio of chitosan, carboxymethyl cellulose, and sodium allyl sulfonate is 2:1:0.8; wherein the initiator is ammonium persulfate or sodium persulfate.

[0029] The embodiment of the present invention also includes a method for preparing a phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system, and the preparation steps are as follows:

[0030] ① According to weight, take 1-3 parts of brown algae extract, 3-11 parts of sodium alginate, 40-80 parts of deionized water, 6-10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2-10 parts of attapulgite, and 2-7 parts of carboxymethyl dextran for later use;

[0031] ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 30-35°C, then add brown algae extract, stir for 5-10 minutes, and continue to heat the reactor to 40-45°C;

[0032] ③ Then put the attapulgite into the reactor and stir for 5-10 minutes. Heat the reactor to 50-60°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor warm at 60°C and stir for 1.5-3 hours. Cool to room temperature to obtain the scale inhibitor.

[0033] In order to make the present invention easier to understand, the phosphorus-free scale inhibitor applicable to the saline-alkali water desalination reverse osmosis system and the preparation method of the present invention are further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] A phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 1 part of kelp extract, 3 parts of sodium alginate, 40 parts of deionized water, 6 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2 parts of attapulgite, and 2 parts of carboxymethyl dextran.

[0036] The method for preparing the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system comprises the following steps:

[0037] ① According to weight, take 1 part of kelp extract, 3 parts of sodium alginate, 40 parts of deionized water, 6 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2 parts of attapulgite, and 2 parts of carboxymethyl dextran for later use;

[0038] ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 30°C, then add brown algae extract, stir for 10 minutes, and continue to heat the reactor to 40°C;

[0039] ③ Then put the attapulgite into the reactor and stir for 10 minutes. Heat the reactor to 50°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor warm at 60°C, stir and react for 3 hours, and cool to room temperature to obtain the scale inhibitor.

[0040] The scale inhibitor prepared in Example 1 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 1655 mg / L, the alkalinity was 280 mg / L (calculated as calcium carbonate), and the silicate was 15.4 mg / L. The reverse osmosis device was stably operated for 6 months, and the pressure difference before and after the reverse osmosis membrane, the water production and the conductivity of the produced water remained basically unchanged, showing excellent scale inhibition performance.

[0041] Example 2

[0042] A phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 3 parts of undaria pinnatifida extract, 11 parts of sodium alginate, 80 parts of deionized water, 10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 10 parts of attapulgite, and 7 parts of carboxymethyl dextran.

[0043] The method for preparing the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system comprises the following steps:

[0044] ① According to weight, take 3 parts of kelp extract, 11 parts of sodium alginate, 80 parts of deionized water, 10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 10 parts of attapulgite, and 7 parts of carboxymethyl dextran for later use;

[0045] ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 35°C, then add brown algae extract, stir for 5 minutes, and continue to heat the reactor to 45°C;

[0046] ③ Then put the attapulgite into the reactor and stir for 5 minutes. Heat the reactor to 60°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor at 60°C and stir for 1.5 hours. Cool to room temperature to obtain the scale inhibitor.

[0047] The scale inhibitor prepared in Example 2 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 2155 mg / L, the alkalinity was 303.6 mg / L (calculated as calcium carbonate), and the silicate was 16.4 mg / L. The reverse osmosis device was stably operated for 6 months, and the pressure difference before and after the reverse osmosis membrane, the water production and the conductivity of the produced water remained basically unchanged, showing excellent scale inhibition performance.

[0048] Example 3

[0049] A phosphorus-free scale inhibitor suitable for a saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 2 parts of Sargassum extract, 8 parts of sodium alginate, 60 parts of deionized water, 8 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran.

[0050] The method for preparing the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system comprises the following steps:

[0051] ① According to weight, take 2 parts of Sargassum extract, 8 parts of sodium alginate, 60 parts of deionized water, 8 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran for later use;

[0052] ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 32°C, then add brown algae extract, stir for 8 minutes, and continue to heat the reactor to 42°C;

[0053] ③ Then put the attapulgite into the reactor and stir for 7 minutes. Heat the reactor to 55°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor warm at 60°C, stir and react for 2 hours, and cool to room temperature to obtain the scale inhibitor.

[0054] The scale inhibitor prepared in Example 3 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 3105 mg / L, the alkalinity was 386 mg / L (calculated as calcium carbonate), and the silicate was 17.8 mg / L. The reverse osmosis device was stably operated for 6 months, and the pressure difference before and after the reverse osmosis membrane, the water production and the conductivity of the produced water remained basically unchanged, showing excellent scale inhibition performance.

[0055] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

[0056] Comparative Example 1

[0057] The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 8 parts of sodium alginate, 60 parts of deionized water, 8 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran.

[0058] The preparation method of the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system in the above-mentioned comparative example 1 is consistent with the preparation method described in Example 3.

[0059] The scale inhibitor prepared in Comparative Example 1 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 3105 mg / L, the alkalinity was 386 mg / L (calculated as calcium carbonate), and the silicate was 17.8 mg / L. The reverse osmosis device was stably operated for 6 months. The pressure difference before and after the reverse osmosis membrane increased, the water production decreased, and the conductivity of the produced water increased.

[0060] Comparative Example 2

[0061] The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 2 parts of Sargassum extract, 8 parts of sodium alginate, 60 parts of deionized water, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran.

[0062] The preparation method of the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system in the above-mentioned comparative example 2 is consistent with the preparation method described in Example 3.

[0063] The scale inhibitor prepared in Comparative Example 1 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 3105 mg / L, the alkalinity was 386 mg / L (calculated as calcium carbonate), and the silicate was 17.8 mg / L. The reverse osmosis device was stably operated for 6 months. The pressure difference before and after the reverse osmosis membrane increased, the water production decreased, and the conductivity of the produced water increased.

[0064] Comparative Example 3

[0065] The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 2 parts of Sargassum extract, 60 parts of deionized water, 8 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran.

[0066] The preparation method of the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system in the above-mentioned comparative example 3 is consistent with the preparation method described in Example 3.

[0067] The scale inhibitor prepared in Comparative Example 1 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 3105 mg / L, the alkalinity was 386 mg / L (calculated as calcium carbonate), and the silicate was 17.8 mg / L. The reverse osmosis device was stably operated for 6 months. The pressure difference before and after the reverse osmosis membrane increased, the water production decreased, and the conductivity of the produced water increased.

[0068] Comparative Example 4

[0069] The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system is composed of the following raw materials in parts by weight: 60 parts of deionized water, 8 parts of attapulgite, and 5 parts of carboxymethyl dextran.

[0070] The preparation method of the phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system in the above-mentioned comparative example 4 is consistent with the preparation method described in Example 3.

[0071] The scale inhibitor prepared in Comparative Example 1 was applied to the reverse osmosis membrane system of a sewage treatment plant, and the addition amount was 9 mg / L. The conductivity of the sewage inlet water was between 3000-7000 μs / cm, the salt content was 3105 mg / L, the alkalinity was 386 mg / L (calculated as calcium carbonate), and the silicate was 17.8 mg / L. The reverse osmosis device was stably operated for 6 months, and the pressure difference before and after the reverse osmosis membrane increased significantly, the water production decreased seriously, and the conductivity of the produced water increased significantly.

[0072] Test example

[0073] The phosphorus-free scale inhibitors suitable for saline-alkali water reverse osmosis systems prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to a static scale inhibition performance comparison test (inhibition of calcium carbonate scale and calcium sulfate scale).

[0074] Test methods

[0075] ①Static test of calcium carbonate scale inhibition efficiency

[0076] The experiment adopts GB / T16632-2018 (GB / T16632-2008) and the specific steps are as follows: use CaCl 2 ·2H 2 O and NaHCO3 Prepare the experimental water sample with a calcium ion concentration of 240 mg / L and a bicarbonate ion concentration of 732 mg / L. Use borax buffer solution to adjust the water sample to a pH of about 9 and place it in a water bath at 80°C for 10 hours. After cooling to room temperature, filter the water sample, transfer 25 mL of the filtrate to a conical flask, add water to about 80 mL, add 5 mL of potassium hydroxide solution (3.5 mol / L) and 0.1 g of calcium-carboxylic acid indicator, and titrate Ca with EDTA solution (0.01 mol / L). 2+ Mass concentration and calculate the scale inhibition rate.

[0077] ②Calcium sulfate scale inhibition static test

[0078] Use deionized water to prepare a certain mass concentration of CaCl 2 and Na 2 SO 4 Water sample, Ca 2+ and SO 4 2- The molar ratio of Ca is 1:1. Take equal amounts of two water samples, add appropriate amount of scale inhibitor, adjust pH with borax, let stand in 80℃ water bath for 10h, cool and take the upper liquid and filter it quickly with filter paper. 2+ The mass concentration was tested by EDTA complexometric titration. The results are shown in Table 1.

[0079] Table 1

[0080]

[0081] As can be seen from the data in Table 1, the scale inhibitors prepared in Examples 1-3 of the present invention performed well in the static scale inhibition test, and both the calcium carbonate scale inhibition rate and the calcium sulfate scale inhibition rate were above 90%. In addition, the products prepared by the present invention do not contain organic phosphine and inorganic phosphate (salt), which reduces the growth of bacteria and algae and the adhesion of slime, reduces the pollution of the reverse osmosis membrane, and is convenient for wide promotion and application.

[0082] It can be seen from the data of Comparative Examples 1-4 that the scale inhibition performance of the scale inhibitor obtained by the present invention can be significantly improved by compounding brown algae extract, sodium alginate, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, etc.

Claims

1. A phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system, characterized by: It is composed of brown algae extract, sodium alginate, deionized water, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, carboxymethyl dextran and attapulgite; The preparation method of the brown algae extract is specifically as follows: the brown algae is cleaned with distilled water, dried in a constant temperature oven at 45°C to constant weight, and then crushed into coarse powder, mixed with distilled water at a weight ratio of 1:15, heated with stirring at 80°C for 6 hours, cooled to room temperature, vacuum filtered, and dried to obtain the brown algae extract.

2. The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system according to claim 1, characterized in that: The weight proportions of the components of the scale inhibitor are as follows: 1-3 parts of brown algae extract, 3-11 parts of sodium alginate, 40-80 parts of deionized water, 6-10 parts of chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, 2-7 parts of carboxymethyl dextran, and 2-10 parts of attapulgite.

3. A phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system according to claim 1 or 2, characterized in that: The brown algae extract is: any one of kelp extract, undaria pinnatifida extract, giant kelp extract, water cloud extract, string algae extract, acid algae extract, hemerocallis extract, cystalgae extract, rope algae extract, chickweed extract, web algae extract, fan algae extract, sargassum extract, antler's eye extract, wormwood extract, sea millet extract, and sea lettuce extract, or a mixture of any two or more of them in any proportion.

4. The phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system according to claim 3, characterized in that: The brown algae extract is Sargassum extract.

5. The method for preparing a phosphorus-free scale inhibitor suitable for saline-alkali water reverse osmosis system according to any one of claims 1 to 4, characterized in that: The following steps are involved: ① Take brown algae extract, sodium alginate, deionized water, chitosan-carboxymethyl cellulose-allyl sulfonic acid copolymer, carboxymethyl dextran and attapulgite according to weight proportions for later use; ②Put sodium alginate and carboxymethyl dextran into the reactor, add deionized water and stir evenly, raise the temperature in the reactor to 30-35℃, then add brown algae extract, stir for 5-10 minutes, and continue to heat the reactor to 40-45℃; ③ Then put the attapulgite into the reactor and stir for 5-10 minutes. Heat the reactor to 50-60°C, add chitosan-oxidized microcrystalline cellulose-allyl sulfonic acid copolymer, keep the reactor warm at 60°C and stir for 1.5-3 hours. Cool to room temperature to obtain the scale inhibitor.

6. The phosphorus-free scale inhibitor according to claim 1 is used in the treatment of high-salt and high-alkali water using a reverse osmosis membrane system, characterized in that: The scale inhibitor is added to saline water at a concentration of 4 mg / L.

7. The use according to claim 6, characterized in that: The saline water has a salt content of 1000-5000 mg / L and an alkalinity of 200-400 mg in terms of calcium carbonate.

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