Preparation method and application of silicon quantum dot water treatment agent with corrosion and scale inhibition performance

Abstract

The application provides a preparation method of a silicon quantum dot water treatment agent with corrosion and scale inhibition performance, wherein trimethylsilicon imidazole is used as a silicon source, carboxymethyl cellulose is used as a modifier, and trisodium citrate is used as a reducing agent, which are dispersed in ultrapure water, and then stirring is performed to obtain a mixed solution; the obtained mixed solution is transferred to a reaction container for heating reaction, and a silicon quantum dot solution is obtained; the silicon quantum dot solution is centrifuged, and then purified and dried to obtain a solid silicon quantum dot water treatment agent. The silicon quantum dot water treatment agent can be applied to carbon steel under neutral and acidic conditions to achieve the purpose of corrosion inhibition, and can effectively inhibit calcium scale in a solution prone to forming calcium sulfate scale and calcium carbonate scale.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment agent preparation, and specifically relates to a preparation method and application of a silicon quantum dot water treatment agent with corrosion and scale inhibition properties. Background Art

[0002] During the operation of circulating cooling water systems, deposits (scale) often accumulate on the metal surfaces of cooling equipment. Most cooling equipment, such as heat exchangers, is made of carbon steel. The presence of deposits significantly reduces the heat exchanger's cooling efficiency and creates the necessary conditions for under-scale corrosion. Water treatment agents with excellent corrosion and scale inhibition properties can not only effectively inhibit scaling and corrosion in circulating cooling water, saving circulating cooling water usage, but also extend the service life of equipment.

[0003] Most water treatment agent solutions are: phosphorus-based, zinc-based, and fully organic formulas, among which phosphorus-based ones account for the largest proportion.

[0004] Over the past five years, non-metallic quantum dots have been widely used in the field of metal corrosion and protection due to their unique biocompatibility and photochemical properties. Non-metallic quantum dot water treatment agents are primarily carbon quantum dots. Through surface modification with nitrogen, sulfur, or functional groups, they form coordination compounds with metal ions, thereby delaying metal corrosion and scaling. Compared to carbon, silicon has excellent corrosion inhibition properties, and traditional silicon-based corrosion inhibitors have been widely used. Therefore, modified silicon quantum dots are more suitable for use as water treatment agents. However, research on silicon quantum dot water treatment agents is relatively rare, and even fewer have practical application value.

[0005] The method to control corrosion and scaling is to add corrosion inhibitors and scale inhibitors to cooling water. Scale inhibitors focus on solving problems such as reduced heat transfer efficiency and equipment blockage caused by scale formation. Corrosion inhibitors: are suitable for situations where metal equipment needs to be protected from corrosion. In water treatment systems containing corrosive media (such as acids, alkalis, salts, etc.), the use of corrosion inhibitors can effectively extend the service life of the equipment. However, the development and research of traditional water treatment agents usually do not focus on their additional functions in addition to testing a single performance, so there is currently little research on multifunctional water treatment agents. Taking into account the characteristics of different water treatment agents, targeted regulation and design of the structure of corrosion inhibitors and scale inhibitors, and the preparation of composite agents that integrate multiple functions are key technologies that are lacking in the application of water treatment agents in actual industrial circulating cooling water systems, and urgently need to be studied in depth by relevant researchers.

[0006] Currently, non-metallic, environmentally friendly quantum dot corrosion inhibitors, represented by carbon quantum dots, have been extensively researched. However, further research is needed into multifunctional quantum dot corrosion inhibitors that combine corrosion and scale inhibition. Therefore, silicon quantum dots are being used in water treatment technology to achieve even better results. However, such research is rare both domestically and internationally, and even fewer have proven to be practically applicable. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties. The silicon quantum dot water treatment agent is prepared using trisodium citrate, carboxymethyl cellulose and trimethylsilyl imidazole as raw materials by optimizing the hydrothermal process parameters. The silicon quantum dot water treatment agent can be applied to carbon steel under neutral and acidic conditions to achieve the purpose of corrosion inhibition, and can effectively inhibit calcium scale in solutions that are prone to forming calcium sulfate scale and calcium carbonate scale.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties comprises the following steps:

[0010] S1: Disperse the silicon source, modifier and reducing agent in ultrapure water, mix and stir for 35-55 minutes to obtain a mixed solution;

[0011] S2: transferring the mixed solution obtained in step S1 to a hydrothermal reaction vessel for reaction to obtain a silicon quantum dot solution;

[0012] S3: Centrifuging the silicon quantum dot solution obtained in step S2, purifying, and freeze-drying to obtain a solid silicon quantum dot water treatment agent.

[0013] Furthermore, in step S1, the mass ratio of the silicon source, the modifier and the reducing agent is 5-7:1:1; and the solid-liquid ratio of the silicon source and ultrapure water is 2-4 g:10 ml.

[0014] Furthermore, the silicon source is trimethylsilyl imidazole, the modifier is one of carboxymethyl cellulose, gum arabic or chitosan, and the reducing agent is trisodium citrate.

[0015] Furthermore, in step S2, the reaction is carried out at a temperature of 210-230° C. for 2-6 hours.

[0016] Furthermore, the characteristics of the silicon quantum dots in step S2 are that they are surface carboxylated and hydroxylated in structure; the lattice spacing is 0.19 nm, and the average diameter is 3.56 nm; the indicators are: they have the dual functions of corrosion inhibition and scale inhibition, and the efficiency of inhibiting calcium sulfate scale is very high. When the addition amount is only 6 mg / L, the inhibition efficiency of calcium sulfate scale reaches 99.99%, and the water solubility is good.

[0017] Furthermore, the process parameters of the centrifugation in step S3 are: centrifugal speed 5000-10000 rpm, centrifugal time 10-30 min.

[0018] Furthermore, the purification process in step S3 is: dialyzing for 24-36 hours using a dialysis bag with a cutoff of 800-1500 Da; and the drying process is: drying at a temperature of -50°C for 48-60 hours.

[0019] The above-mentioned silicon quantum dot water treatment agent is used for corrosion inhibition of carbon steel under neutral and acidic conditions. The silicon quantum dot water treatment agent is applied to the surface of the metal substrate of Q235 carbon steel in a 3.5wt% NaCl solution and a 0.5 mol / L HCl environment. The dosage of the silicon quantum dot water treatment agent is 20-100 mg / L.

[0020] The silicon quantum dot water treatment agent is used in a solution that is prone to forming calcium sulfate scale, and 0.5-6 mg / L of the silicon quantum dot water treatment agent is added to the solution that is prone to forming calcium sulfate scale.

[0021] The silicon quantum dot water treatment agent is used in a solution that is prone to forming calcium carbonate scale, and 5-150 mg / L of the silicon quantum dot water treatment agent is added to the solution that is prone to forming calcium carbonate scale.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0023] 1. The present invention uses trisodium citrate, carboxymethyl cellulose and trimethylsilyl imidazole as raw materials, combines the inherent properties of silicon itself such as good biocompatibility, environmental friendliness and low price, and the characteristics of carboxymethyl cellulose with good corrosion inhibition effect and good water solubility, adopts a simple hydrothermal method to synthesize blue silicon quantum dots in one step, and innovatively uses them in the field of water treatment technology. The above raw materials are cheap and easy to obtain, the operation is green and environmentally friendly, and it is easy to produce on a large scale in factories. The characteristics of the silicon quantum dots prepared by the present invention are: silicon quantum dots with carboxylation and hydroxylation on the surface

[0024] The crystal spacing is 0.19 nm, with an average diameter of 3.56 nm. It also has dual corrosion and scale inhibition functions. Its calcium sulfate scale inhibition efficiency is extremely high, reaching 99.99% at a dosage of only 6 mg / L. It also has excellent water solubility.

[0025] 2. The water treatment agent of the present invention has a wide range of uses and has a good corrosion and scale inhibition effect on common metal or alloy surfaces in complex polluted environments.

[0026] 3. When the silicon quantum dot water treatment agent is added at a concentration of 100 mg / L, the corrosion inhibition efficiency of Q235 carbon steel is 93.68% when immersed in a 0.5 mol / L HCl environment; the corrosion inhibition efficiency is 93.33% when immersed in a 3.5 wt.% NaCl solution; it has a significant inhibitory effect on the corrosion of hydrochloric acid and sodium chloride.

[0027] 4. When the silicon quantum dot water treatment agent of the present invention is added at a concentration of 6 mg / L, the inhibition efficiency of calcium sulfate scale reaches 99.99%; when the addition concentration reaches 150 mg / L, the inhibition efficiency of calcium carbonate scale is 26.45%; it has a certain inhibitory effect on the formation of two types of calcium scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the preparation process of silicon quantum dot water treatment agent;

[0029] Figure 2 Characterization diagrams of silicon quantum dot water treatment agents: transmission electron microscopy images (a, b), high-resolution transmission electron microscopy image (c), and particle size distribution diagram (d);

[0030] Figure 3 This is the infrared spectrum of silicon quantum dots;

[0031] Figure 4 This is the experimental diagram of weight loss of Q235 steel by silicon quantum dots in 0.5 mol / L HCl solution;

[0032] Figure 5 This is the experimental graph of weight loss of Q235 steel by silicon quantum dots in 3.5 wt.% NaCl solution;

[0033] Figure 6 The potentiodynamic polarization curve of silicon quantum dots on Q235 steel in 0.5 mol / L HCl solution;

[0034] Figure 7 The potentiodynamic polarization curve of silicon quantum dots on Q235 steel in 3.5 wt.% NaCl solution;

[0035] Figure 8 This is a scale inhibition test diagram of silicon quantum dot water treatment agent for calcium sulfate and calcium carbonate;

[0036] Figure 9 These are scale diagrams after the scale inhibition test of silicon quantum dot water treatment agent: comparison of changes in calcium sulfate scale before and after adding silicon quantum dot water treatment agent (a, b); comparison of changes in calcium carbonate scale before and after adding silicon quantum dot water treatment agent (c, d). DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0038] The sources used in the present application are as follows:

[0039] The reagents used, unless otherwise specified, can be purchased from conventional biochemical reagent companies, and all aqueous solutions are prepared by using ultrapure water. The Q235 carbon steel is obtained from Jiangsu Gaomiao Matian Ltd. (China), and its chemical composition (in terms of percentage by weight) is as follows: carbon 0.17%; manganese 0.37%; silicon 0.20%; sulfur 0.03%; phosphorus 0.01%, and the remaining components are iron. Before the test is carried out, the sample is first mechanically polished by using silicon carbide papers with particle sizes of 300, 1000 and 1500 respectively, then washed with acetone, and vacuum dried for standby use.

[0040] Embodiment 1

[0041] The present embodiment provides a preparation method of a silicon quantum dot water treatment agent, comprising the following steps:

[0042] S1: 1.8 g of trisodium citrate and 1.8 g of carboxymethyl cellulose are dissolved in 48 mL of ultrapure water, and 12 mL of trimethylsilylimidazole is added dropwise under stirring to obtain a mixed solution;

[0043] S2: The mixed solution obtained in step S1 is transferred into a hydrothermal reaction kettle, and hydrothermal reaction is carried out at 220°C for 2 h, and then cooled to room temperature to obtain a silicon quantum dot solution;

[0044] S3: The silicon quantum dot solution obtained in step S2 is transferred to a centrifuge, and the centrifugal speed is 5000 rpm, and the centrifugal time is 10 min; after removing the solid impurities, the supernatant is taken and purified by dialysis with a 1000 Da dialysis bag, and the dialysis time is 24 h; after the dialysis is completed, it is transferred and freeze-dried at a temperature of -50°C for 48 h; finally, the product silicon quantum dot water treatment agent is obtained, and stored at 4°C for standby use.

[0045] Embodiment 2

[0046] The present embodiment provides a preparation method of a silicon quantum dot water treatment agent, comprising the following steps:

[0047] S1: 1.8 g of trisodium citrate and 1.8 g of carboxymethyl cellulose are dissolved in 48 mL of ultrapure water, and 12 mL of trimethylsilylimidazole is added dropwise under stirring to obtain a mixed solution;

[0048] S2: The mixed solution obtained in step S1 is transferred into a hydrothermal reactor, subjected to a hydrothermal reaction at 220° C. for 2 h, and then cooled to room temperature to obtain a silicon quantum dot solution;

[0049] S3: The silicon quantum dot solution obtained in step S2 was transferred to a centrifuge at a speed of 6000 rpm for 15 min. After removing solid impurities, the supernatant was taken and purified by dialyzing using a 1000 Da dialysis bag for 36 h. After the dialysis was completed, the solution was transferred and freeze-dried at -50°C for 60 h. Finally, the product silicon quantum dot water treatment agent was obtained and stored at 4°C for use.

[0050] Example 3

[0051] This embodiment provides a method for preparing a silicon quantum dot water treatment agent, comprising the following steps:

[0052] S1: Dissolve 1.8 g of trisodium citrate and 1.8 g of carboxymethyl cellulose in 48 mL of ultrapure water, and add 12 mL of trimethylsilyl imidazole dropwise while stirring to obtain a mixed solution;

[0053] S2: The mixed solution obtained in step S1 is transferred into a hydrothermal reactor, subjected to a hydrothermal reaction at 220° C. for 2 h, and then cooled to room temperature to obtain a silicon quantum dot solution;

[0054] S3: The silicon quantum dot solution obtained in step S2 was transferred to a centrifuge at a speed of 5800 rpm for 12 min. After removing solid impurities, the supernatant was taken and purified by dialyzing using a 1000 Da dialysis bag for 30 h. After the dialysis was completed, the solution was transferred and freeze-dried at -50°C for 52 h. Finally, the product silicon quantum dot water treatment agent was obtained and stored at 4°C for use.

[0055] Example 4

[0056] The difference from Example 1 is that the modifier is gum arabic, and the other steps are the same. When the concentration of 100 mg / L is added, the corrosion inhibition efficiency of Q235 carbon steel immersed in a 0.5 mol / L HCl environment reaches 93.28%, and when immersed in a 3.5 wt.% NaCl solution, the corrosion inhibition efficiency reaches 89.02%. It has a significant inhibitory effect on corrosion by hydrochloric acid and sodium chloride.

[0057] Example 5

[0058] The difference from Example 1 is that chitosan is used as the modifier; all other steps are the same. When chitosan is added at a concentration of 100 mg / L, the corrosion inhibition efficiency of Q235 carbon steel reaches 63.95% when immersed in a 0.5 mol / L HCl environment; and 70.61% when immersed in a 3.5 wt.% NaCl solution. The corrosion inhibition is significantly inhibited by hydrochloric acid and sodium chloride.

[0059] The silicon quantum dots obtained in Example 1 were characterized by FTIR and TEM. Figure 2 Transmission electron micrographs of water-soluble silicon quantum dots are shown. Panels a and b show uniform distribution of the silicon quantum dots. Panel c shows a high-resolution transmission electron micrograph of the silicon quantum dots with a lattice spacing of 0.19 nm, indicating excellent crystallinity. Panel d shows an average diameter of 3.56 nm, calculated from measurements of 110 particles.

[0060] like Figure 3 The infrared spectrum of the water-soluble silicon quantum dots prepared in Example 1 shows: FTIR (KBr), ν: 3440, 2935, 1650, 1155 and 1078 cm -1 3440 cm -1 The absorption peak at 2935 cm indicates the presence of -OH and -NH2 groups on the surface of silicon quantum dots; -1 The absorption peak at 1650 cm -1 The peaks at 1115 and 1078 cm correspond to -COOH groups. -1 The observed absorption peaks indicate the presence of COC / Si-O-Si bonds. These findings reveal that the surface of silicon quantum dots contains abundant hydroxyl and carboxyl groups, and these functional hydrophilic groups significantly enhance their solubility in water and their scale and corrosion inhibition properties.

[0061] The corrosion inhibition and scale inhibition performance tests of the silicon quantum dot water treatment agent prepared in Example 1 were conducted using the following test methods:

[0062] (1) Corrosion inhibition performance study - static weight loss

[0063] The static weight loss method was used to evaluate the corrosion inhibition performance of the silicon quantum dot water treatment agent. The corrosion weight loss test was carried out in accordance with the national standard GB 10124-88 "Laboratory uniform corrosion full immersion test method for metal materials".

[0064] The experimental material was Q235 carbon steel, with specimens measuring 5.0 × 2.5 × 0.2 cm. The specimens were polished with sandpaper, treated with anhydrous ethanol, dried, and weighed. The initial mass of the carbon steel was recorded. The weighed specimens were statically suspended in a blank solution and in a circulating water solution containing different corrosion inhibitor concentrations. After immersion for 24 hours, they were removed, cleaned, dried, and weighed. The post-corrosion mass was recorded. The difference in mass before and after corrosion was used to calculate the corrosion rate, inhibition efficiency, and surface coverage.

[0065] (2) Potentiodynamic polarization curve measurement

[0066] The electrochemical test was carried out in a 0.5 mol / L hydrochloric acid solution containing different concentrations of silicon quantum dots. The hydrochloric acid solution without corrosion inhibitor was used as a blank control, and the temperature was controlled in a constant temperature water bath. A saturated calomel electrode (SCE) was used as the reference electrode, a platinum electrode was used as the auxiliary electrode, and a carbon steel electrode was used as the working electrode. Before the electrochemical test, the three-electrode system was immersed in the test solution and the open circuit potential was stabilized to ensure that the feedback of the electrochemical signal depends only on the liquid-solid interface state and to exclude interference from adverse external factors. The scanning range of the potentiodynamic polarization curve was -700 ~ -150 mV, and the scanning rate was 1.0 mV·s -1 , the scanning direction is from negative to positive.

[0067] (3) Scale inhibition performance research - static scale inhibition

[0068] The static scale inhibition method was used to evaluate the scale inhibition performance of the silicon quantum dot water treatment agent. The inhibition test of calcium sulfate was carried out in accordance with the national standard GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agents - Calcium carbonate precipitation method", and the inhibition test of calcium carbonate was carried out in accordance with the industry standard SY / T 5673-2020 "General Technical Conditions for Scale Inhibitors for Oilfields".

[0069] The addition of a scale inhibitor can inhibit the formation of scale in the water, meaning that the amount of calcium sulfate or calcium carbonate precipitates is reduced, and the concentration of free calcium ions in the water is higher than in water without the scale inhibitor. The scale inhibition rate can be calculated based on the change in calcium ion concentration in the blank water sample before and after the experiment and in the water sample after the scale inhibitor was added.

[0070] The silicon quantum dot water treatment agent prepared in Example 1 was added to a 0.5 mol / L HCl solution and a 3.5 wt.% NaCl solution, respectively, to prepare corrosion inhibitor solutions at concentrations of 20, 40, 60, 80, and 100 mg / L. Electrochemical measurements were performed in the above solutions using the treated carbon steel substrate as the working electrode, a saturated calomel electrode as the reference electrode, and platinum as the counter electrode. The resulting polarization curves and corrosion current densities are shown in Figures 6 and 7. Furthermore, the corrosion rate of the substrate was calculated and analyzed using the weight loss method after immersion, with the results shown in Figures 4 and 5.

[0071] Figures 6 and 7 show that the corrosion current density of Q235 steel decreases significantly after the addition of silicon quantum dots compared to the blank condition. This indicates that the addition of silicon quantum dot corrosion inhibitors significantly slows the corrosion of carbon steel by corrosive media (hydrochloric acid and sodium chloride solutions), making them a mixed corrosion inhibitor primarily focused on inhibiting anodic corrosion. Their corrosion inhibition primarily relies on the formation of a physical barrier (hydrophobic protective layer) and chemical adsorption resulting from metal coordination-chelation interactions.

[0072] The silicon quantum dot water treatment agent prepared in Example 1 was added to standard test solutions at concentrations of 1, 2, 3, 4, 5, and 6 mg / L to inhibit calcium sulfate scale, and 5, 10, 50, 100, and 150 mg / L to inhibit calcium carbonate scale. Scale inhibition performance was tested using the static scale inhibition test method described above. The scale inhibition efficiency of the silicon quantum dot water treatment agent for calcium sulfate and calcium carbonate is shown in Figure 8.

[0073] In addition, Example 1 also shows a scale diagram after the silicon quantum dot water treatment agent scale inhibition test. As shown in Figure 9, the silicon quantum dot water treatment agent can destroy the structure of calcium sulfate and calcium carbonate crystals, changing the surface shape and particle size, demonstrating significant scale inhibition performance.

[0074] Example 6

[0075] When the modifier carboxymethyl cellulose (CAS: 9000-11-7) was used directly at a concentration of 18 mg / L, its inhibition efficiency against calcium sulfate scale reached 78.05%, showing some inhibitory effect on calcium sulfate scale formation, but its scale inhibition performance was weaker than that of the silicon quantum dot water treatment agent of the present invention. At a concentration of 100 mg / L, the corrosion inhibition efficiency of Q235 carbon steel immersed in a 0.5 mol / L HCl environment reached 39.97%, and when immersed in a 3.5 wt.% NaCl solution, the corrosion inhibition efficiency reached 43.16%. While it showed some inhibitory effect on corrosion by hydrochloric acid and sodium chloride, its corrosion inhibition performance was weaker than that of the silicon quantum dot water treatment agent of the present invention. In summary, the scale and corrosion inhibition performance of carboxymethyl cellulose was inferior to that of the silicon quantum dot water treatment agent of the present invention.

[0076] Example 7

[0077] According to the document published in 2024, "Carboxyl-Engineered Silicon Quantum Dots(CSiQDs) as an Efficient Scale Inhibitor: Formulation Inhibition Mechanism" (see Ismail, N. , Alshami, A. , Tikeri, G. , Sun, D. , Tayyebi, A. ,&Al-Goraee, AM , et al. (2024). Carboxyl-engineered silicon quantum dots(csiqds) as an efficient scale inhibitor: formulation inhibition mechanism.Industrial&Engineering Chemistry Research, 63(16), 12.), carboxyl silicon quantum dots (CSiQDs) scale inhibitor was prepared. When the addition concentration reaches 20 mg / L, the inhibition efficiency of calcium sulfate scale reaches 100%, and it has a certain inhibitory effect on the formation of calcium sulfate scale, but its scale inhibition performance is weaker than that of the silicon quantum dot water treatment agent. When the addition concentration is 100 mg / L, the corrosion inhibition efficiency of Q235 carbon steel immersed in a 0.5 mol / L HCl environment reaches 11.06%; when immersed in a 3.5wt.% NaCl solution, the corrosion inhibition efficiency reaches 13.52%. There is no significant inhibitory effect on the corrosion of hydrochloric acid and sodium chloride, and the corrosion inhibition performance is weaker than that of the silicon quantum dot water treatment agent of the present invention. In summary, the scale and corrosion inhibition performance of CSiQDs reported in this document is inferior to that of the silicon quantum dot water treatment agent of the present invention.

[0078] Example 8

[0079] Based on the patent "Carboxymethyl Cellulose-Based Sulfur Quantum Dot Scale Inhibitor" (CN202311546267.6), published in 2023, a carboxymethyl cellulose-based sulfur quantum dot scale inhibitor (CMC-SQDs) was prepared. At a dosage concentration of 0.8 mg / L, the inhibition efficiency against calcium sulfate scale reached 100%, surpassing the scale inhibition performance of the silicon quantum dot water treatment agent of the present invention. However, at a dosage concentration of 100 mg / L, when Q235 carbon steel was immersed in a 0.5 mol / L HCl environment, the corrosion inhibition efficiency was only 0.23%, indicating no corrosion inhibition effect. When immersed in a 3.5 wt.% NaCl solution, the corrosion inhibition efficiency was only 4.01%, indicating no significant inhibitory effect on hydrochloric acid and sodium chloride corrosion, indicating no corrosion inhibition performance. In summary, the CMC-SQDs reported in this patent have excellent scale inhibition performance, but lack corrosion inhibition performance. In contrast, the multifunctional silicon quantum dot water treatment agent of the present invention, which has both corrosion inhibition and scale inhibition properties, can achieve a better "one dose, multiple effects" technical effect.

[0080] Example 9

[0081] According to the document published in 2019 "Synthesis and application of CCQDs as a noveltype of environmentally friendly scale inhibitor" (see: Hao, JianLi, LingyunZhao, WeiweiWu, XiaqianXiao, YangyangZhang, HongfengTang, NaWang,Xiaocong. (2019). Synthesis and application of ccqds as a novel type ofenvironmentally friendly scale inhibitor. ACS applied materials&interfaces,11(9).), carboxyl carbon quantum dot scale inhibitors (CCQDs) were prepared. When the addition concentration reaches 200 mg / L, the inhibition efficiency of calcium sulfate scale reaches 100%, and when the addition concentration reaches 20 mg / L, the inhibition efficiency of barium sulfate scale reaches 100%, and the scale inhibition performance is weaker than the silicon quantum dot water treatment agent of the present invention; when the addition concentration is 100 mg / L, the corrosion inhibition efficiency of Q235 carbon steel immersed in 0.5 mol / L HCl environment reaches 29.59%, and there is no corrosion inhibition effect; when immersed in 3.5wt.% NaCl solution, the corrosion inhibition efficiency reaches 36.10%; it has a certain inhibitory effect on the corrosion of hydrochloric acid and sodium chloride, and the corrosion inhibition performance is weaker than the silicon quantum dot water treatment agent of the present invention. In summary, the scale and corrosion inhibition performance of CCQDs reported in this document are inferior to the silicon quantum dot water treatment agent of the present invention.

[0082] Compared with existing corrosion and scale inhibition technologies, silicon quantum dots offer advantages such as a simple synthesis process, mild reaction conditions, readily available raw materials, a green, non-toxic, and easily degradable product, and low raw material costs. Furthermore, silicon quantum dots synthesized via a hydrothermal method using trisodium citrate and carboxymethyl cellulose have demonstrated corrosion inhibition efficiencies exceeding 90%, scale inhibition efficiencies exceeding 99% for calcium sulfate, and a moderate inhibitory effect on calcium carbonate.

[0083] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties, characterized in that: The steps include: S1: Disperse a silicon source, a modifier, and a reducing agent in ultrapure water, mix and stir for 35-55 minutes to obtain a mixed solution; the silicon source is trimethylsilyl imidazole, the modifier is one of carboxymethyl cellulose, chitosan, or gum arabic, and the reducing agent is trisodium citrate; S2: transferring the mixed solution obtained in step S1 to a reaction vessel for reaction to obtain a silicon quantum dot solution; S3: Centrifuging the silicon quantum dot solution obtained in step S2, purifying, and freeze-drying to obtain a solid silicon quantum dot water treatment agent.

2. The method for preparing a silicon quantum dot water treatment agent having corrosion and scale inhibition properties according to claim 1, characterized in that: The mass ratio of the silicon source, the modifier and the reducing agent in step S1 is 5-7:1:1; the solid-liquid ratio of the silicon source and ultrapure water is 2-5g:10ml.

3. The method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to claim 1, characterized in that: In step S2, the reaction is carried out at a temperature of 210-230° C. for 2-6 hours.

4. The method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to claim 1, characterized in that: The characteristics of the silicon quantum dots in step S2 are: water-soluble silicon quantum dots that have completed carboxylation and hydroxylation, and a large number of -COOH and -OH groups are modified on the surface.

5. The method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to claim 1, characterized in that: The process parameters of the centrifugation in step S3 are: centrifugal speed 5000-10000 rpm, centrifugal time 10-30 min.

6. The method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to claim 1, characterized in that: The purification process in step S3 is: dialysis using a dialysis bag with a cutoff of 800-1500 Da for 24-36 hours; the freeze-drying process is: drying at a temperature of -50°C for 48-60 hours.

7. The silicon quantum dot water treatment agent prepared by the method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to any one of claims 1 to 6 is used for corrosion inhibition of carbon steel under neutral and acidic conditions, characterized in that: When Q235 carbon steel is in a 3.5wt% NaCl solution and a 0.5 mol / L HCl environment, a silicon quantum dot water treatment agent is applied to the surface of the metal substrate, and the dosage of the silicon quantum dot water treatment agent is 20-100 mg / L.

8. The silicon quantum dot water treatment agent prepared by the method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to any one of claims 1 to 6 is used in a solution prone to forming calcium sulfate scale, characterized in that: In solutions that are prone to forming calcium sulfate scale, the dosage of silicon quantum dot water treatment agent is 0.5-6 mg / L.

9. The silicon quantum dot water treatment agent prepared by the method for preparing a silicon quantum dot water treatment agent with corrosion and scale inhibition properties according to any one of claims 1 to 6 is used in a solution prone to forming calcium carbonate scale, characterized in that: In solutions that are prone to forming calcium carbonate scale, the dosage of silicon quantum dot water treatment agent is 5-150 mg / L.

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