Preparation method of novel sewage demulsifier
By modifying chitosan quaternary ammonium salt Schiff base derivative demulsifiers, the problems of large dosage and secondary pollution of traditional demulsifiers have been solved, achieving efficient and environmentally friendly industrial wastewater treatment that can adapt to complex water quality and quantity fluctuations.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-13
AI Technical Summary
In existing industrial wastewater treatment, the stability of emulsions makes demulsification and separation difficult. Traditional demulsifiers require large quantities, are costly, and are prone to causing secondary pollution. Physical methods have low efficiency and a narrow range of applications, making it difficult to meet the treatment needs of complex industrial wastewater.
Chitosan was used as a raw material to synthesize a chitosan quaternary ammonium salt Schiff base derivative through a two-step modification reaction. 3-chloro-2-hydroxypropyltrimethylammonium chloride and pyridine-2-carboxaldehyde were introduced to improve its hydrophilicity and water solubility, and to generate carbon-nitrogen double bonds and positive charges, thereby disrupting the emulsion balance.
The newly prepared demulsifier requires a small dosage, is biodegradable, is suitable for treating complex industrial wastewater, reduces costs, improves demulsification efficiency, and reduces environmental pollution, thus showing good prospects for industrialization.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for preparing a novel wastewater demulsifier. Background Technology
[0002] In the field of industrial wastewater treatment, the stable properties of emulsions pose a significant challenge to demulsification and separation. Naturally occurring substances in wastewater, such as colloids and asphaltenes, spontaneously form stable emulsion systems, significantly increasing the difficulty of demulsification. Simultaneously, these types of wastewater generally exhibit a small density difference between oil and water, further hindering the oil-water separation process. Furthermore, industrial wastewater often contains high-density mineral oil, and its quality and quantity fluctuate in real-time with the production process, making traditional demulsification processes inadequate and severely impacting demulsification efficiency and separation effectiveness, thus failing to meet the requirements for compliant industrial wastewater treatment. Currently used chemical demulsifiers are mostly synthetic polymers. While they have some demulsification effect, they suffer from drawbacks such as large dosage, high cost, and potential secondary pollution. Physical demulsification methods are limited by equipment, resulting in low treatment efficiency and a narrow range of applications. Against this backdrop, the development of chitosan biomass-based demulsifiers is of great significance. Chitosan, derived from natural biomass, possesses advantages such as good biocompatibility, biodegradability, and no secondary pollution. Furthermore, its active groups, such as amino and hydroxyl groups, can interact with emulsifying substances in wastewater, disrupting the emulsion balance and enhancing the demulsification effect. Developing a method for preparing chitosan biomass-based demulsifiers can effectively address the shortcomings of traditional demulsification technologies, meet the treatment needs of complex industrial wastewater, and possess both environmental and economic value, playing a crucial role in promoting the upgrading of industrial wastewater treatment technologies.
[0003] Therefore, it is necessary to provide a novel method for preparing a wastewater demulsifier. Summary of the Invention
[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a novel method for preparing a wastewater demulsifier.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a novel wastewater demulsifier includes the following steps: using chitosan as a raw material, different solubility regulators and different reactants are introduced under different acidic or alkaline environments and reacted in two steps to synthesize a modified chitosan quaternary ammonium salt Schiff base derivative, which is then dissolved in water to obtain the novel wastewater demulsifier.
[0006] Further, in the first step of the reaction, chitosan was added to isopropanol and stirred at a moderate temperature. Then, 3-chloro-2-hydroxypropyltrimethylammonium chloride was added, and the reaction continued under moderate temperature conditions. After the reaction was completed, precipitation, filtration, and drying were performed. In the second step of the reaction, chitosan quaternary ammonium salt (the product of the first step) was added to methanol under an acidic environment, followed by pyridine-2-carboxaldehyde. The reaction was carried out under moderate temperature conditions. After the reaction was completed, precipitation, filtration, and drying were performed to obtain the chitosan quaternary ammonium salt Schiff base derivative modified in two steps.
[0007] Preferably, the concentration of 3-chloro-2-hydroxypropyltrimethylammonium chloride is 65%~70%.
[0008] Preferably, the concentration of pyridine-2-carboxaldehyde is 95% to 100%.
[0009] Preferably, isopropanol is used as the solubility regulator in the first step. This solubility regulator can adjust the polarity of the reaction system, helping chitosan and 3-chloro-2-hydroxypropyltrimethylammonium chloride to disperse and dissolve better, ensuring sufficient contact and reaction between the two. Simultaneously, this regulator can also reduce the viscosity of the system, facilitating subsequent separation. Methanol is used as the solubility regulator in the second step. Although chitosan quaternary ammonium salt (the product of the first step) is more soluble than raw chitosan, it still has limited solubility in some systems. Methanol, as a regulator, can help chitosan quaternary ammonium salt and pyridine-2-carboxaldehyde to fully dissolve and disperse, ensuring uniform reaction. Furthermore, methanol can prevent side reactions such as excessive polymerization of aldehydes.
[0010] This invention also provides a method for preparing a novel wastewater demulsifier, comprising the following steps: (1) Add chitosan to isopropanol and stir magnetically under medium temperature conditions; (2) Gradually add 65%~70% 3-chloro-2-hydroxypropyltrimethylammonium chloride to the reaction flask and stir magnetically under medium temperature conditions; (3) After the reaction is complete, the solution is cooled to room temperature and its pH value is measured. If it is not neutral, it is neutralized. Then, ethanol is added to precipitate and separate the product, which is then filtered, washed, and finally dried to constant weight. (4) Under acidic conditions, chitosan quaternary ammonium salt [the product obtained in step (3)] was added to methanol, and then pyridine-2-carboxaldehyde with a concentration of 95%~100% was added. The mixture was magnetically stirred and refluxed under medium temperature conditions. (5) After the reaction is complete, the solution is cooled to room temperature, and then cold acetone solution is added to precipitate and separate the product. The product is filtered, washed, and finally dried to constant weight to obtain the chitosan quaternary ammonium salt Schiff base derivative after two modifications.
[0011] Preferably, the stirring time in step (1) is 3-5 hours and the temperature is 50-60℃.
[0012] Preferably, the stirring time in step (2) is 12-16 hours and the temperature is 65-75℃.
[0013] Preferably, the stirring time in step (4) is 10-14 hours and the temperature is 60-70℃.
[0014] Preferably, vacuum drying is used in both steps (3) and (5).
[0015] The present invention also provides a novel wastewater demulsifier for use in wastewater demulsification. The reaction steps are as follows: add the demulsifier to the wastewater, stir for 30 minutes, and let stand for 60 minutes to obtain a demulsified water sample.
[0016] The steps are as follows: Add the demulsifier to the wastewater, stir for 30 minutes, and let it stand for 60 minutes to obtain the demulsified water sample.
[0017] Compared with the prior art, the advantages of the present invention are: (1) The chitosan quaternary ammonium salt Schiff base derivative obtained by the present invention through two modifications under different conditions solves the problem that single chitosan has poor water solubility and general inhibition effect. The chitosan is modified by introducing 3-chloro-2-hydroxypropyltrimethylammonium chloride and pyridine-2-carboxaldehyde. On the one hand, it improves hydrophilicity and water solubility. On the other hand, by introducing aldehydes to combine with amino-NH2 on chitosan to generate carbon-nitrogen double bond -C=N- (i.e. Schiff base structure) and positively charged quaternary ammonium salt groups, it can affect the arrangement of water molecules and reduce the possibility of hydrogen bonds forming between water molecules.
[0018] (2) The novel wastewater demulsifier used in this invention requires a small dosage and has high biodegradability during wastewater treatment, thus reducing environmental pollution. Furthermore, the novel wastewater demulsifier used in this invention is suitable for treating complex industrial wastewater.
[0019] (3) The demulsifier provided by the present invention is easy to prepare and has a low cost, and has good industrialization prospects. Detailed Implementation
[0020] The present invention will now be described in further detail with reference to the embodiments.
[0021] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventionally available products. Isopropanol, CAS No.: 67-63-0, was purchased from Shanghai Maclean's Biochemical Technology Co., Ltd.; 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, CAS No.: 3327-22-8, was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.; pyridine-2-carboxaldehyde, CAS No.: 1121-60-4, was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.
[0022] Example 1 This embodiment provides a novel wastewater demulsifier, the preparation process of which is as follows: (1) Weigh 4.0g of chitosan and 50mL of isopropanol using an electronic balance, and add them to the reaction flask in sequence. Stir magnetically at 50℃ for 4h.
[0023] (2) Gradually add 30 mL of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution and stir magnetically at 65°C for 15 h.
[0024] (3) After the reaction is complete, measure the pH value of the mixture in the reaction flask. If it is not neutral, carry out a neutralization reaction until it is neutral.
[0025] (4) Add ethanol to precipitate and separate the product, filter, wash, and dry under vacuum at 80°C to obtain chitosan quaternary ammonium salt.
[0026] (5) Measure 75 mL of methanol, weigh 2.0 g of chitosan quaternary ammonium salt prepared in step (4) using an electronic balance, measure 4.72 mL of pyridine-2-carboxaldehyde and 10 mL of acetic acid, add them to the reaction flask in sequence, and reflux at 60 °C for 12 h.
[0027] (6) After cooling to room temperature, add cold acetone solution to precipitate, filter, wash, and vacuum dry at 50°C to obtain the modified chitosan quaternary ammonium salt Schiff base derivative.
[0028] Example 2 This embodiment provides a novel wastewater demulsifier, the preparation process of which is as follows: (1) Weigh 4.0g of chitosan and 50mL of isopropanol using an electronic balance, and add them to the reaction flask in sequence. Stir magnetically at 50℃ for 4h.
[0029] (2) Gradually add 30 mL of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution and stir magnetically at 65°C for 15 h.
[0030] (3) After the reaction is complete, measure the pH value of the mixture in the reaction flask. If it is not neutral, carry out a neutralization reaction until it is neutral.
[0031] (4) Add ethanol to precipitate and separate the product, filter, wash, and dry under vacuum at 80°C to obtain chitosan quaternary ammonium salt.
[0032] (5) Measure 75 mL of methanol, weigh 2.0 g of chitosan quaternary ammonium salt prepared in step (4) using an electronic balance, measure 4.72 mL of pyridine-2-carboxaldehyde and 10 mL of acetic acid, add them to the reaction flask in sequence, and reflux at 70 °C for 12 h.
[0033] (6) After cooling to room temperature, add cold acetone solution to precipitate, filter, wash, and vacuum dry at 50°C to obtain the modified chitosan quaternary ammonium salt Schiff base derivative.
[0034] Example 3 This embodiment provides a novel wastewater demulsifier, the preparation process of which is as follows: (1) Weigh 4.0g of chitosan and 50mL of isopropanol using an electronic balance, and add them to the reaction flask in sequence. Stir magnetically at 60℃ for 4h.
[0035] (2) Gradually add 30 mL of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution and stir magnetically at 75°C for 15 h.
[0036] (3) After the reaction is complete, measure the pH value of the mixture in the reaction flask. If it is not neutral, carry out a neutralization reaction until it is neutral.
[0037] (4) Add ethanol to precipitate and separate the product, filter, wash, and dry under vacuum at 80°C to obtain chitosan quaternary ammonium salt.
[0038] (5) Measure 75 mL of methanol, weigh 2.0 g of chitosan quaternary ammonium salt prepared in step (4) using an electronic balance, measure 4.72 mL of pyridine-2-carboxaldehyde and 10 mL of acetic acid, add them to the reaction flask in sequence, and reflux at 70 °C for 12 h.
[0039] (6) After cooling to room temperature, add cold acetone solution to precipitate, filter, wash, and vacuum dry at 50°C to obtain the modified chitosan quaternary ammonium salt Schiff base derivative.
[0040] Example 4 This embodiment provides a novel wastewater demulsifier, the preparation process of which is as follows: (1) Weigh 4.0g of chitosan and 50mL of isopropanol using an electronic balance, and add them to the reaction flask in sequence. Stir magnetically at 55℃ for 4h.
[0041] (2) Gradually add 30 mL of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution and stir magnetically at 65°C for 15 h.
[0042] (3) After the reaction is complete, measure the pH value of the mixture in the reaction flask. If it is not neutral, carry out a neutralization reaction until it is neutral.
[0043] (4) Add ethanol to precipitate and separate the product, filter, wash, and dry under vacuum at 80°C to obtain chitosan quaternary ammonium salt.
[0044] (5) Measure 75 mL of methanol, weigh 2.0 g of chitosan quaternary ammonium salt prepared in step (4) using an electronic balance, measure 4.72 mL of pyridine-2-carboxaldehyde and 10 mL of acetic acid, add them to the reaction flask in sequence, and reflux at 70 °C for 12 h.
[0045] (6) After cooling to room temperature, add cold acetone solution to precipitate, filter, wash, and vacuum dry at 50°C to obtain the modified chitosan quaternary ammonium salt Schiff base derivative.
[0046] Comparative Example 1 (1) Weigh 4.0g of chitosan and 50mL of isopropanol using an electronic balance, and add them to the reaction flask in sequence. Stir magnetically at 55℃ for 4h.
[0047] (2) Gradually add 30 mL of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution and stir magnetically at 65°C for 15 h.
[0048] (3) After the reaction is complete, measure the pH value of the mixture in the reaction flask. If it is not neutral, carry out a neutralization reaction until it is neutral.
[0049] (4) Add ethanol to precipitate and separate the product, filter, wash, and dry under vacuum at 80°C to obtain chitosan quaternary ammonium salt.
[0050] Weigh 4.0 g of chitosan and 50 mL of isopropanol using an electronic balance, and add them sequentially to the reaction flask. Stir magnetically at 55 °C for 4 h. Filter, wash, and dry under vacuum at 80 °C.
[0051] Table 1. Demulsification performance of wastewater demulsifiers in Examples 1-4 and Comparative Examples 1-2 Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 1 Transmittance (%) 96.2 94.3 97.4 92.1 82 63 absorbance 0.432 0.443 0.412 0.491 0.544 0.592 Settlement rate (%) 95.4 94.2 96.5 93.6 82.5 71.4 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing comparative examples, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a novel wastewater demulsifier, characterized in that, The preparation method of the demulsifier is as follows: (1) Chitosan was added to isopropanol and magnetically stirred under medium temperature conditions; (2) Gradually add 65%~70% 3-chloro-2-hydroxypropyltrimethylammonium chloride to the reaction flask and stir magnetically under medium temperature conditions; (3) After the reaction is complete, the solution is cooled to room temperature and its pH value is measured. If it is not neutral, it is neutralized. Then, ethanol is added to precipitate and separate the product, which is then filtered, washed, and finally dried to constant weight. (4) Under acidic conditions, chitosan quaternary ammonium salt [the product obtained in step (3)] was added to methanol, and then pyridine-2-carboxaldehyde with a concentration of 95%~100% was added. The mixture was magnetically stirred and refluxed under medium temperature conditions. (5) After the reaction is complete, the solution is cooled to room temperature, then cold acetone solution is added to precipitate and separate the product, filter, wash, and finally dry to constant weight to obtain the chitosan quaternary ammonium salt Schiff base derivative after two modifications. Its structural formula is shown below:
2. Wherein, A is the substituted cationic surfactant group, and B is the substituted pyridine group.
3. The method for preparing a novel wastewater demulsifier according to claim 1, characterized in that, The reaction requires two steps, and the drugs needed for each step are different. The reactants in the first step are chitosan and 3-chloro-2-hydroxypropyltrimethylammonium chloride; the reaction in the second step is chitosan quaternary ammonium salt (the product of the first step) and pyridine-2-carboxaldehyde.
4. The method for preparing a novel wastewater demulsifier according to claim 1, characterized in that, The solubility regulator in the first step is isopropanol, and the solubility regulator in the second step is methanol.
5. The method for preparing a novel wastewater demulsifier according to claim 1, characterized in that, The concentration of 3-chloro-2-hydroxypropyltrimethylammonium chloride is 65%~70%, and the concentration of pyridine-2-carboxaldehyde is 95%~100%.
6. The method for preparing a novel wastewater demulsifier according to claim 1, characterized in that, The reaction temperature is 60℃~100℃.
7. The method for preparing a novel wastewater demulsifier according to claim 1, characterized in that, The reaction time is 10 h-24 h.