A uniform and stable silicon-free defoaming agent for evaporators

Abstract

The present invention discloses a uniform and stable silicon-free defoamer for evaporators. The defoamer comprises the following ingredients by weight: 20-23% propylene glycol block polyether L61, 42-46% propylene glycol block polyether L62, 20-23% octadecyl alcohol, 3-5% tributyl phosphate, 1-3% Tween 80, 0.8-1.2% stearic acid, and 2-4% tert-butylbenzoic acid. The silicon-free defoamer has the advantages of high temperature resistance, excellent defoaming and anti-foaming properties, a simple preparation method, a wide range of raw material sources, and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a uniform and stable silicon-free defoaming agent for an evaporator. Background Art

[0002] Evaporation concentration is one of the important technologies for full-scale membrane treatment of sewage. Some substances contained in sewage (polymers - derivatives + hydrocarbons, floating matter - grease, impurities, surfactants, etc.) are prone to foaming during the evaporation process. A large amount of foam can easily cause material leakage, boiling over, and other phenomena, affecting the evaporation and filtration effects of the evaporator, reducing evaporation efficiency, causing damage to the equipment, and affecting equipment utilization.

[0003] Currently, silicone and polyether defoamers are primarily used. Silicone defoamers dissolve in water, increasing the silicon content. Over time, this can lead to membrane fouling and equipment scaling in membrane-based full-scale treatment processes. Silicone defoamers have low surface tension and strong defoaming capabilities, but poor anti-foaming properties. They are also less stable in high-temperature or high-alkaline environments, leading to demulsification and precipitation. They also contain silicon, which can affect membrane life and easily scale equipment. Polyether defoamers alone are heat-resistant, but exhibit poor anti-foaming and defoaming properties, requiring high usage and resulting in high costs.

[0004] Prior art CN105688452A discloses an emulsion-type silicone defoamer and a preparation method thereof. The silicone defoamer has a faster defoaming speed, stronger antifoaming ability, longer-lasting action time, and lower cost. However, it is prone to demulsification under high temperature conditions, the defoamer performance is reduced, and it contains silicon that is prone to cause membrane pollution.

[0005] The prior art CN110950396A discloses a defoaming agent for landfill leachate and a preparation method thereof. The defoaming agent does not cause membrane blockage in the treatment equipment, its foam suppression ability is significantly improved, the preparation method is simple, and the equipment requirements are low. However, its raw materials are relatively scarce, the cost is high, and the defoaming ability is poor.

[0006] Therefore, it is necessary to develop an efficient and low-cost silicon-free defoamer for evaporators to suppress the foaming phenomenon of the evaporator. Summary of the Invention

[0007] The object of the present invention is to provide a silicon-free defoaming agent for evaporators which has high temperature resistance, excellent defoaming and anti-foaming properties, a simple preparation method, a wide source of raw materials and a low price.

[0008] To achieve the above object, the present invention provides a uniform and stable silicon-free defoaming agent for evaporator, characterized in that it comprises the following components in percentage by weight:

[0009] Propylene glycol block polyether L61: 22~24%;

[0010] Propylene glycol block polyether L62: 44~48%;

[0011] Octadecanol: 22~24%;

[0012] Tributyl phosphate: 2~4%;

[0013] Tween 80: 1~3%;

[0014] Stearic acid: 0.8~1.2%;

[0015] Tert-butylbenzoic acid: 1.5~2.5.

[0016] Furthermore, the average molecular weight of the propylene glycol block polyether L61 is 1800-2200.

[0017] Furthermore, the average molecular weight of the propylene glycol block polyether L61 is 2000.

[0018] Furthermore, the average molecular weight of the propylene glycol block polyether L62 is 2400-2600.

[0019] Furthermore, the average molecular weight of the propylene glycol block polyether L62 is 2500.

[0020] Furthermore, the preparation method is as follows: propylene glycol block polyether L61 and L62, octadecyl alcohol, tributyl phosphate, Tween 80, stearic acid, and tert-butyl benzoic acid are added to a stirring tank in proportion, and then stirred at 60-70° C. for 30 minutes and allowed to stand for 30 minutes.

[0021] The propylene glycol block polyethers L61 and L62 and octadecanol of the present invention, as main agents, significantly reduce the surface tension of the foam when dissolved in the foam. However, since these substances generally have low solubility in water, the reduction in surface tension is limited to a local area of ​​the foam, while the surface tension around the foam remains almost unchanged. The portion with reduced surface tension is strongly pulled and extended in all directions, eventually breaking. When added to the foam system, the portion diffuses toward the gas-liquid interface, making it difficult for the surfactant with a foam-stabilizing effect to restore film elasticity, causing the foam to break. Furthermore, the propylene glycol block polyethers L61 and L62 and octadecanol, as main agents, are relatively low in cost and have a wide market source.

[0022] The present invention preferably uses propylene glycol block polyether L61 with an average molecular weight of 2000 and L62 with an average molecular weight of 2500, which are moderate in molecular weight. This is because lower relative molecular weight of the polyether and higher hydroxyl value not only directly affect the solubility of the product but also increase the product's cloud point, reducing the product's defoaming ability at room temperature. Higher relative molecular weight of the polyether increases the viscosity of the product prepared using it as a reaction raw material, hindering the product's dispersion in aqueous solution and significantly weakening its defoaming performance.

[0023] The octadecyl alcohol of the present invention has suitable defoaming activity and is composed of a hydrophobic alkyl group and a hydrophilic hydroxyl group. The appropriate ratio of hydrophilic and hydrophobic groups provides the most suitable defoaming activity for foam.

[0024] The present invention uses tributyl phosphate as an auxiliary agent, which solubilizes the foaming agent (surfactant) and reduces its effective concentration. This not only reduces the concentration of the foaming agent in the surface layer but also dissolves into the adsorption layer of the foaming agent, reducing the tightness between the foaming agent molecules, thereby weakening the stability of the foam. Tributyl phosphate, as an auxiliary agent, facilitates the integration of the defoamer and the foaming system, facilitating its dispersion into the foaming system. Its inherent low surface tension helps suppress foaming. Furthermore, as an organic phosphate, tributyl phosphate destabilizes the charge on the bubble film surface, accelerating its aging and coalescence, and synergistically defoaming with other components.

[0025] The Tween 80 used in the present invention as an emulsifier can enhance the stability of the defoaming agent, disperse the active ingredients into small particles, facilitate their dispersion in water, and better achieve defoaming and anti-foaming effects.

[0026] The stearic acid of the present invention, as hydrophobic particles, can achieve better emulsification effect, help the defoamer oil droplets to reach the liquid film surface more easily, reduce the repulsive effect between the defoamer oil droplets and the foam liquid film, and improve the defoaming performance.

[0027] The tert-butylbenzoic acid of the present invention, as an anti-precipitation agent, has a large spatial structure, can be adsorbed onto the surface of hydrophobic particles (stearic acid), and fully stretches in the solvent to form a steric layer, thereby increasing the steric hindrance of the particles, effectively preventing agglomeration between particles, and enhancing the stability of the defoaming agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a photo of the silicone-free defoamer of formula 24 after being placed for 14 days.

[0029] Figure 2 This is a photo of the defoaming agent in Case 31 after 14 days of storage.

[0030] Figure 3 This is a photo of the defoaming agent in Case 32 after 14 days of storage. DETAILED DESCRIPTION

[0031] Below in detail embodiments of the present invention, the example of described embodiment is shown in the accompanying drawings, wherein identical or similar reference numerals represent identical or similar elements or elements with identical or similar functions throughout. The embodiment described below by reference to the accompanying drawings is exemplary, is intended to be used for explaining the present invention, and is not to be construed as limiting the present invention. In the embodiment, those not indicating specific techniques or conditions are carried out according to the technology or conditions described in the document in this area or according to the product specification. Reagents used or instruments not indicating manufacturers are conventional products that can be obtained commercially.

[0032] Defoamer performance test

[0033] Defoaming property: Pour 1 ml of foaming liquid (1% sodium dodecylbenzenesulfonate solution) and 20 ml of deionized water into a 100 ml stoppered graduated cylinder, shake 30 times with the same intensity, add 0.2 ml of defoaming agent solution (1%), and record the foam volume after 5 minutes. For a blank test, do not add defoaming agent and use the same other conditions.

[0034]

[0035] Foam suppression: Pour 1 ml of foaming solution (1% sodium dodecylbenzenesulfonate solution), 20 ml of deionized water and 0.2 ml of defoamer solution (1%) into a 100 ml stoppered graduated cylinder. Shake 30 times with the same intensity and record the foam volume after 5 minutes. For a blank test, do not add defoamer and use the same other conditions.

[0036] .

[0037] Example 1: Screening test of propylene glycol block polyether L61 and propylene glycol block polyether L62

[0038] Formula 1: Add 92 parts of polyoxyethylene glycerol ether, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butyl benzoic acid into a stirring tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 1.

[0039] Recipe 2: Combine 92 parts of C 12 -C 14 Fatty alcohol polyoxyethylene polyoxypropylene, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butyl benzoic acid were added to a stirring tank in proportion, and then stirred at 60-70°C for 30 minutes and allowed to stand for 30 minutes to obtain the defoaming agent. The performance of the defoaming agent was tested; the results are shown in Table 1.

[0040] Formula 3: Add 92 parts of polyether F68, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butylbenzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoamer performance was tested; the results are shown in Table 1.

[0041] Formula 4: Add 92 parts of propylene glycol block polyether L61, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butyl benzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 1.

[0042] Formula 5: Add 92 parts of propylene glycol block polyether L62, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butyl benzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoamer performance was tested; the results are shown in Table 1.

[0043] Formula 6: Add 92 parts of propylene glycol random polyether PPE-1500, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butyl benzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 1.

[0044] Table 1 Defoamer performance test results of formula 1-6

[0045]

[0046] It can be seen from the test results of the defoaming agents of formulas 1 to 6 that among the common polyethers selected, propylene glycol block polyether L61 has the strongest antifoaming performance, and propylene glycol block polyether L62 has the strongest defoaming performance. Therefore, propylene glycol block polyether L61 and propylene glycol block polyether L62 are selected as the main agents of the compound defoaming agent.

[0047] Example 2: Screening test of octadecanol

[0048] Formula 7: Add 92 parts of dodecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butylbenzoic acid into a stirring tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 2.

[0049] Formula 8: Add 92 parts of hexadecanol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butylbenzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 2.

[0050] Formula 9: Add 92 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butylbenzoic acid into a stirring tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 2.

[0051] Formula 10: Add 92 parts of behenyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 2 parts of tert-butylbenzoic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested; the results are shown in Table 2.

[0052] Table 2 Defoamer performance test results of formula 7-10

[0053]

[0054] From the test results of defoamers in formulas 7 to 10, it can be seen that as the molecular weight of higher alcohols increases from 12 to 22, the defoaming rate changes slightly, but octadecanol has the best foaming inhibition rate. Therefore, octadecanol is selected as the main agent of the compound defoamer.

[0055] Example 3: Dosage screening test

[0056] Formulas 11-28: Add propylene glycol block polyether L61 and L62, octadecyl alcohol, tributyl phosphate, Tween 80, stearic acid, and tert-butylbenzoic acid into a stirring tank in the order of the mass ratio in Table 2. Then stir at 60-70°C for 30 minutes and let it stand for 30 minutes. The defoaming agent performance was tested. The formula and results are shown in Table 3.

[0057] Table 3 Composition mass ratio and results of implementation formulas 11 to 28

[0058]

[0059] From the test results of defoamers of formulas 11 to 28, it can be seen that the defoamer of formula 24 has the best performance (see Figure 1 , which is a photo of the silicon-free defoamer obtained from Recipe 24 after 14 days of storage), and is superior to existing competing defoamers on the market. Therefore, the dosage within the scope of protection of this invention has a better effect.

[0060] Formulation 29: Add 23.5 parts of propylene glycol block polyether L61, 46 parts of propylene glycol block polyether L62, 23.5 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, and 2 parts of tert-butyl benzoic acid in proportion to a stirring tank, then stir at 60-70°C for 30 minutes and let stand for 30 minutes. Observe the state of the defoamer after standing for 14 days and test the defoamer performance; the results are shown in Table 4.

[0061] Formulation 30: 23 parts of propylene glycol block polyether L61, 46 parts of propylene glycol block polyether L62, 23.5 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 0.5 parts of stearic acid, and 2 parts of tert-butyl benzoic acid were added to a stirring tank in proportion, and then stirred at 60-70°C for 30 minutes and allowed to stand for 30 minutes. The state of the defoamer was observed after standing for 14 days, and the defoamer performance was tested; the results are shown in Table 4.

[0062] Formulation 31: 22.5 parts of propylene glycol block polyether L61, 46 parts of propylene glycol block polyether L62, 22.5 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 2 parts of stearic acid, and 2 parts of tert-butyl benzoic acid were added to a stirring tank in proportion, and then stirred at 60-70°C for 30 minutes and allowed to stand for 30 minutes. The state of the defoamer was observed after standing for 14 days, and the defoamer performance was tested; the results are shown in Table 4.

[0063] Table 4 Performance of formulas 29 to 34 and competing defoamers

[0064]

[0065] Note: Market competitor 1: Jinan Xingfeilong Chemical Co., Ltd. polyether defoamer PPE-860;

[0066] Market competitor 2: Jiangsu Tengda Additives Co., Ltd. T-3400 high-efficiency non-silicone defoaming agent;

[0067] Market competitor 3: Jiangsu Tengda Additive Co., Ltd. TSA-822 high-temperature silicone defoaming agent.

[0068] From the comparison of the test results of the defoamers of formulas 24, 29 and 30, it can be seen that the hydrophobic particles of stearic acid have a greater impact on the defoamer. The lower the content, the worse the defoamer performance. However, if the content is too high (see formula 31), the defoamer contains insoluble solids (see Figure 2 , which is a photo of the silicon-free defoamer obtained from formula 31 after being left for 14 days). Therefore, the appropriate proportion of stearic acid is 1%;

[0069] Formulation 32: Add 23.5 parts of propylene glycol block polyether L61, 47 parts of propylene glycol block polyether L62, 23.5 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, and 1 part of stearic acid in a mixing tank in proportion, then stir at 60-70°C for 30 minutes and let stand for 30 minutes. Observe the state of the defoamer after standing for 14 days and test the defoamer performance; the results are shown in Table 4.

[0070] Formulation 33: 22.5 parts of propylene glycol block polyether L61, 45 parts of propylene glycol block polyether L62, 22.5 parts of octadecyl alcohol, 3 parts of tributyl phosphate, 2 parts of Tween 80, 1 part of stearic acid, and 4 parts of tert-butyl benzoic acid were added to a stirring tank in proportion, and then stirred at 60-70°C for 30 minutes and allowed to stand for 30 minutes. The defoamer was observed after standing for 14 days and its performance was tested. The results are shown in Table 4.

[0071] From the comparison of the defoamers of formula 24, 32 and 33 after 14 days of standing, it can be seen that the defoamer of formula 32 is stratified and has flocs sinking to the bottom (see Figure 3 , which is a photo of the silicone-free defoamer obtained from formula 32 after being left for 14 days). The defoamers of formulas 24 and 33 are uniform and stable turbid liquids (similar in appearance), but the performance of the defoamer of formula 33 is significantly reduced. This shows that the appropriate content of tert-butylbenzoic acid is 2%.

[0072] Example 4-7: Preparation of a uniform and stable silicon-free defoamer for evaporators

[0073] Materials and amounts: see Table 5.

[0074] Preparation method: Add each reagent in proportion to the stirring tank, then stir at 60~70℃ for 30 minutes and let it stand for 30 minutes.

[0075] After preparation, the performance was tested and the results are shown in Table 5.

[0076] It can be seen from the results of Examples 4 to 15 that the components are within the scope of protection of the claims, the performance of the defoamer does not change significantly and the performance is excellent.

[0077] Table 5 Composition mass ratio and results of Examples 4 to 7

[0078]

[0079] Practical Application

[0080] Practical Application 1: The silicon-free defoamer obtained from Formula 24 of the present invention was added to an evaporation concentration tank at a landfill leachate treatment site at a certain concentration. After continuous operation for 90 days, the evaporation tank was cooled to room temperature. After opening, no sticky substance remained on the inner wall of the tank, the filter screen, and the heating tube bundle, and no white substance precipitated. This shows that the defoamer of the present invention has good heat resistance and stability, and is not prone to demulsification and precipitation.

[0081] Practical Application 2: Competitor 3's defoamer was added to an evaporation and concentration tank at a landfill leachate treatment site at a certain concentration. After 30 days of operation, the tank was cooled to room temperature. Upon opening, residual scale was observed on the inner wall of the tank, which was confirmed to be silica scale.

[0082] Practical Application 3: The defoamer of competitor product 1 was added to an evaporation concentration tank at a landfill leachate treatment site at a certain concentration. After 90 days of continuous operation, the defoamer consumption was twice the amount of the defoamer used in the present invention.

[0083] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A uniform and stable silicon-free defoamer for evaporator, characterized in that: The following weight percentages of the ingredients are included: Propylene glycol block polyether L61: 22-24%; Propylene glycol block polyether L62: 44-48%; Octadecanol: 22-24%; Tributyl phosphate: 2-4%; Tween 80: 1-3%; Stearic acid: 0.8-1.2%; Tert-butylbenzoic acid: 1.5-2.5%.

2. The uniform and stable silicon-free defoamer for evaporator according to claim 1, characterized in that: The average molecular weight of the propylene glycol block polyether L61 is 1800-2200.

3. The uniform and stable silicon-free defoamer for evaporator according to claim 1, characterized in that: The average molecular weight of the propylene glycol block polyether L61 is 2000.

4. The uniform and stable silicon-free defoamer for evaporator according to claim 1, characterized in that: The average molecular weight of the propylene glycol block polyether L62 is 2400-2600.

5. The uniform and stable silicon-free defoamer for evaporator according to claim 1, characterized in that: The average molecular weight of the propylene glycol block polyether L62 is 2500.

6. The uniform and stable silicon-free defoamer for evaporator according to claim 1, characterized in that: The preparation method is as follows: propylene glycol block polyether L61 and L62, octadecyl alcohol, tributyl phosphate, Tween 80, stearic acid, and tert-butyl benzoic acid are added to a stirring tank in proportion, and then stirred at 60-70°C for 30 minutes and allowed to stand for 30 minutes.

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