High-temperature-resistant sewage treatment silicon polyether defoaming agent and preparation method thereof

Abstract

The application discloses a kind of high-temperature-resistant sewage treatment silicon polyether defoamer and preparation method thereof, belong to defoamer technical field.The high-temperature-resistant sewage treatment silicon polyether defoamer, including the following weight fraction raw materials: POSS hybrid hyperbranched silicon polyether polymer 5-15 parts, imidazolium ionic liquid type self-emulsifying silicon polyether 5-10 parts, low viscosity silicone oil 15-30 parts, porous carrier 4-12 parts, dispersing agent 2-5 parts, stabilizer 0.5-1.0 parts and deionized water 40-60 parts.The high-temperature-resistant sewage treatment silicon polyether defoamer prepared by the application has good dispersibility, thermal stability, rapid defoaming property and long-acting bubble inhibition property.

Description

Technical Field

[0001] This invention relates to the field of defoamer technology, specifically to a high-temperature resistant silicone polyether defoamer for wastewater treatment and its preparation method. Background Technology

[0002] In wastewater treatment, wastewater often contains surfactants, oils, proteins, suspended particles, flocculants, and other organic pollutants. Under aeration, stirring, circulation, and high-temperature treatment conditions, large amounts of stable foam are easily generated. The presence of foam not only affects the effective volume and aeration efficiency of wastewater treatment equipment but may also cause misjudgment of liquid level, foam overflow, sludge entrainment, and instability in the operation of subsequent treatment units. Silicone polyether defoamers are widely used in aqueous systems due to their combination of the low surface tension of organosilicon segments and the water dispersibility of polyether segments. However, existing silicone polyether defoamers still have problems in high-temperature, high-salt, high-alkali, and strongly aerated wastewater systems, such as insufficient heat resistance, easy emulsion demulsification, easy floating of silicone oil, easy solubilization of active components by surfactants in wastewater, and short foam suppression time. At the same time, although ordinary low-viscosity silicone oil has a relatively fast defoaming effect, its water phase dispersibility is poor, and it is easy to produce oil spots or deposits when used alone. On the other hand, excessive introduction of hydrophilic polyethers or emulsifiers may lead to over-emulsification of the defoamer, reducing its ability to enter and destroy the foam film.

[0003] Chinese invention patent CN102350097A discloses a silicone polyether defoamer and its preparation method. The silicone polyether defoamer includes 10-70 parts of water, 32-35 parts of dimethyl silicone oil, 30-35 parts of polyether-modified silicone oil, and 20-25 parts of emulsifier. The silicone polyether defoamer prepared by this invention is not only economical, environmentally friendly, safe, and simple to prepare, but also has good stability and excellent defoaming and foam-suppressing effects. However, its high-temperature stability needs to be improved.

[0004] Therefore, there is an urgent need to develop a silicone polyether defoamer for wastewater treatment that combines rapid defoaming, long-lasting foam suppression, and high-temperature resistance to meet the stable defoaming requirements in high-temperature and complex wastewater systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-temperature resistant silicone polyether defoamer for wastewater treatment and its preparation method.

[0006] A high-temperature resistant silicone polyether defoamer for wastewater treatment comprises the following raw materials in parts by weight: 5-15 parts of POSS hybrid hyperbranched silicone polyether polymer, 5-10 parts of imidazolium ionic liquid self-emulsifying silicone polyether, 15-30 parts of low-viscosity silicone oil, 4-12 parts of porous carrier, 2-5 parts of dispersant, 0.5-1.0 parts of stabilizer, and 40-60 parts of deionized water; The POSS hybrid hyperbranched silicone polyether polymer is prepared by the following method: Octa(dimethylsiloxy)octasesquioxane and divinyl-terminated polydimethylsiloxane were mixed and reacted to obtain a prepolymer reaction solution; then allyl polyoxyethylene ether was added to react, and after post-treatment, POSS hybrid hyperbranched silicone polyether polymer was obtained.

[0007] The imidazolium ionic liquid self-emulsifying silicone polyether is prepared by the following method: A1: Low-hydrogen silicone oil, isopentenyl alcohol polyoxyethylene ether and allyl glycidyl ether react in the presence of a platinum catalyst to generate an intermediate; A2: Intermediate, N-methylimidazolium and N-octylimidazolium react in the presence of a proton transfer aid, and then an acidifying salting agent is added for salting to generate imidazolium ionic liquid self-emulsifying silicone polyether.

[0008] The mass ratio of the octa(dimethylsiloxy)octasesquioxane, divinyl-terminated polydimethylsiloxane, and allyl polyoxyethylene ether is 1:(0.5-2.0):(7-9).

[0009] In step A1, the mass ratio of the low-hydrogen silicone oil, isopentenyl alcohol polyoxyethylene ether, and allyl glycidyl ether is 25:30:3.

[0010] In step A2, the mass ratio of the intermediate, N-methylimidazole, and N-octylimidazole is 100:3.2:1.5.

[0011] The acidifying salt-forming agent is lactic acid.

[0012] The porous carrier is composed of fumed silica and diatomaceous earth in a mass ratio of 1:(1-2).

[0013] The dispersant is a low-foaming fatty alcohol polyoxyethylene ether.

[0014] The stabilizer is sodium alginate.

[0015] A method for preparing a high-temperature resistant silicone polyether defoamer for wastewater treatment includes the following steps: The stabilizer was added to deionized water and stirred to dissolve, thus obtaining the aqueous phase. The POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low-viscosity silicone oil and dispersant were mixed and stirred evenly to obtain the oil phase. The oil phase was slowly added to the aqueous phase, and after shear emulsification and homogenization, it was added to a porous carrier in batches. After stirring and filtration, a high-temperature resistant silicone polyether defoamer for wastewater treatment was obtained.

[0016] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: This application combines POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low-viscosity silicone oil, porous carrier, dispersant, and stabilizer to form a composite silicone polyether defoamer suitable for high-temperature, saline, and surfactant-containing wastewater systems. This defoamer has good high-temperature stability, self-emulsifying dispersibility, rapid defoaming, and sustained foam suppression, and can meet the defoaming requirements in high-temperature, aerated, and complex wastewater treatment systems. Attached Figure Description

[0017] Figure 1 Fourier transform infrared spectrum of the POSS hybrid hyperbranched silicone polyether polymer prepared in Example 1.

[0018] Figure 2 The Fourier transform infrared spectrum of the imidazolium ionic liquid self-emulsifying silicone polyether prepared in Example 4 is shown. Detailed Implementation

[0019] Example 1: Preparation of POSS hybrid hyperbranched silicone polyether polymer Under nitrogen protection, 100 mL of anhydrous toluene, 10 g of octa(dimethylsiloxy)octasesquioxane, and 5 g of divinyl-terminated polydimethylsiloxane were added to a reaction flask, stirred and mixed, and heated to 70 °C. Then, 0.02 g of Karstedt platinum catalyst was added, and the mixture was heated to 80 °C and reacted for 1 h to obtain a prepolymer reaction solution. 70 g of allyl polyoxyethylene ether (number average molecular weight 1000) and 0.03 g of... Karstedt platinum catalyst was dissolved in 200 mL of anhydrous toluene and slowly added dropwise to the prepolymer reaction solution at 85 °C over 1.5 h. The temperature was then raised to 90 °C and the reaction continued for 7 h. The temperature was lowered to 50 °C, 1.0 g of activated carbon was added, and the mixture was stirred for 30 min. The mixture was filtered, and the filtrate was concentrated under reduced pressure at 90 °C and -0.095 MPa for 1 h to obtain a concentrate. The concentrate was then slowly added dropwise to 500 mL of n-hexane over 30 min. The mixture was stirred for another 30 min, centrifuged at 4000 rpm for 10 min, and the supernatant was discarded. The polymer was washed twice with n-hexane (100 mL each time) and once with 50 wt% ethanol aqueous solution (100 mL each time). The polymer was then dried under vacuum at 70 °C for 12 h to obtain the POSS hybrid hyperbranched silicone polyether polymer.

[0020] Figure 1 The figure shows the Fourier transform infrared spectrum of the POSS hybrid hyperbranched silicone polyether polymer. As can be seen from the figure, at 2963 cm⁻¹... -1 and 2873cm -1 The absorption peaks appearing nearby are mainly attributed to -CH3 and -CH 2- The CH stretching vibration indicates the presence of polydimethylsiloxane and polyether organic segments in the product; 1260 cm⁻¹ -1The nearby absorption peaks are attributed to the characteristic vibrational absorption of Si-CH3, further confirming that polydimethylsiloxane segments are incorporated into the product structure. (1110 cm⁻¹) -1 A strong absorption peak appears nearby, mainly due to the overlapping absorption of the Si-O-Si skeleton stretching vibration and the COC stretching vibration in the polyether segment, indicating that the product contains both a siloxane skeleton and a polyether bond structure. (940 cm⁻¹) -1 and 560cm -1 The nearby absorption peaks coincide with the vibrational correlations of the Si-O-Si framework in POSS / silsesquioxane, and can be considered as auxiliary characteristic absorptions related to the presence of the POSS silicon-oxygen framework. Additionally, the absorption peaks in the 2130-2160 cm⁻¹ range... -1 No obvious Si-H characteristic absorption peaks were observed nearby, and at approximately 1635 cm⁻¹... -1 No obvious alkenyl characteristic absorption peaks were observed nearby, indicating that the Si-H in octa(dimethylsiloxy)octasesquioxane underwent a hydrosilylation reaction with the unsaturated double bonds in divinyl-terminated polydimethylsiloxane and allyl polyether. In summary, the infrared spectrum indicates that a POSS hybrid hyperbranched silicone polyether polymer containing a POSS cage-like silicon-oxygen structure, polydimethylsiloxane segments, and polyether segments was successfully prepared.

[0021] Example 2 Preparation of POSS hybrid hyperbranched silicone polyether polymer Under nitrogen protection, 100 mL of anhydrous toluene, 10 g of octa(dimethylsiloxy)octasesquioxane, and 15 g of divinyl-terminated polydimethylsiloxane were added to a reaction flask, stirred and mixed, and heated to 70 °C. Then, 0.02 g of Karstedt platinum catalyst was added, and the mixture was heated to 80 °C and reacted for 1 h to obtain a prepolymer reaction solution. 80 g of allyl polyoxyethylene ether (number average molecular weight 1000) and 0.03 g of... Karstedt platinum catalyst was dissolved in 200 mL of anhydrous toluene and slowly added dropwise to the prepolymer reaction solution at 85 °C over 1.5 h. The temperature was then raised to 95 °C and the reaction continued for 6.5 h. The temperature was lowered to 50 °C, 1.0 g of activated carbon was added, and the mixture was stirred for 30 min. The mixture was filtered, and the filtrate was concentrated under reduced pressure at 90 °C and -0.095 MPa for 1 h to obtain a concentrated solution. The concentrated solution was slowly added dropwise to 500 mL of n-hexane over 30 min. The mixture was stirred for another 30 min, centrifuged at 4000 rpm for 10 min, and the supernatant was discarded. The mixture was washed twice with n-hexane (100 mL each time) and once with 50 wt% ethanol aqueous solution (100 mL each time). The mixture was then dried under vacuum at 70 °C for 12 h to obtain the POSS hybrid hyperbranched silicone polyether polymer.

[0022] Example 3 Preparation of POSS hybrid hyperbranched silicone polyether polymer Under nitrogen protection, 100 mL of anhydrous toluene, 10 g of octa(dimethylsiloxy)octasesquioxane, and 20 g of divinyl-terminated polydimethylsiloxane were added to a reaction flask, stirred and mixed, and heated to 70 °C. Then, 0.02 g of Karstedt platinum catalyst was added, and the mixture was heated to 80 °C and reacted for 1 h to obtain a prepolymer reaction solution. 90 g of allyl polyoxyethylene ether (number average molecular weight 1000) and 0.03 g of... Karstedt platinum catalyst was dissolved in 200 mL of anhydrous toluene and slowly added dropwise to the prepolymer reaction solution at 85 °C over 1.5 h. The temperature was then raised to 100 °C and the reaction continued for 6 h. The temperature was lowered to 50 °C, 1.0 g of activated carbon was added, and the mixture was stirred for 30 min. The mixture was filtered, and the filtrate was concentrated under reduced pressure at 90 °C and -0.095 MPa for 1 h to obtain a concentrated solution. The concentrated solution was slowly added dropwise to 500 mL of n-hexane over 30 min. The mixture was stirred for another 30 min, centrifuged at 4000 rpm for 10 min, and the supernatant was discarded. The mixture was washed twice with n-hexane (100 mL each time) and once with 50 wt% ethanol aqueous solution (100 mL each time). The mixture was then dried under vacuum at 70 °C for 12 h to obtain the POSS hybrid hyperbranched silicone polyether polymer.

[0023] Example 4: Preparation of imidazolium ionic liquid self-emulsifying silicone polyether A1: Under nitrogen protection, 150 mL of anhydrous toluene and 100 g of low-hydrogen silicone oil were added to the reaction flask and stirred until well mixed. The temperature was raised to 75 °C, and 0.12 g of Karstedt platinum catalyst was added. 120 g of isopentenyl alcohol polyoxyethylene ether (TPEG-2400) and 12 g of allyl glycidyl ether were mixed evenly and then slowly added dropwise to the reaction flask. The addition was completed in 1.5 h. The temperature was raised to 90 °C and the reaction was carried out for 5 h. The mixture was then rotary evaporated to constant weight at 80 °C and -0.095 MPa to obtain an epoxy-containing silicone polyether intermediate. A2: Under nitrogen protection, 100 mL of anhydrous isopropanol and 100 g of epoxy-containing silicone polyether intermediate were added to a reaction flask and stirred until well mixed. Then, 3.2 g of N-methylimidazole and 1.5 g of N-octylimidazole were added and stirred until well mixed. 0.4 g of 40 wt% lactic acid anhydrous isopropanol solution was added, and the mixture was heated to 75 °C and reacted for 6 h. Then, the mixture was cooled to 40 °C, and 10 g of 40 wt% lactic acid aqueous solution was slowly added. The mixture was reacted for another 2 h, and then rotary evaporated to constant weight at 65 °C and -0.095 MPa. The mixture was washed twice with a mixed solvent of ethyl acetate and n-hexane (ethyl acetate to n-hexane volume ratio of 1:3) (100 mL each time), and then vacuum dried at 70 °C for 12 h to obtain imidazolium ionic liquid self-emulsifying silicone polyether.

[0024] Figure 2 The image shows the Fourier transform infrared spectrum of imidazolium ionic liquid-type self-emulsifying silicone polyether. As can be seen from the image, at 3445 cm⁻¹... -1The broad absorption peaks observed nearby are mainly attributed to the OH stretching vibrations of the β-hydroxyl groups generated after epoxy ring opening and the terminal hydroxyl groups of the polyether segments; 3130 cm⁻¹ -1 The nearby absorption peak can be attributed to the CH stretching vibration on the imidazolium ring, indicating that the imidazolium structure has been introduced into the product. (2925 cm⁻¹) -1 and 2865cm -1 The nearby absorption peaks are mainly attributed to the CH stretching vibrations of -CH3 and -CH2- in the methyl, polyether, and octyl segments of the siloxane, indicating that the product contains siloxane, polyether, and alkyl segments. (1570 cm⁻¹) -1 The nearby absorption peak is related to the vibration of the imidazole ring skeleton, 1465 cm⁻¹. -1 The nearby absorption peaks are mainly attributed to the imidazole ring and CN-related vibrations, further confirming the introduction of an imidazole structure into the product. (1260 cm⁻¹) -1 The nearby absorption peak is a characteristic absorption peak of Si-CH3, indicating that the product retains polydimethylsiloxane segments; 1100 cm⁻¹ -1 and 1048cm -1 The strong absorption peaks in the vicinity are mainly due to the overlapping absorption of Si-O-Si and COC-related vibrations, indicating that the product contains both a siloxane backbone and polyether segments. (800 cm⁻¹) -1 The nearby absorption peaks can be attributed to Si-C and Si-CH3 related vibrations. In summary, the infrared spectrum indicates that an imidazolium ionic liquid-type self-emulsifying silicone polyether containing polydimethylsiloxane segments, polyether segments, and imidazolium ionic liquid side groups has been prepared.

[0025] Example 5 Preparation of high-temperature resistant silicone polyether defoamer for wastewater treatment (1) Weigh: 50g of POSS hybrid hyperbranched silicone polyether polymer (prepared in Example 1), 50g of imidazolium ionic liquid self-emulsifying silicone polyether (prepared in Example 4), 150g of low viscosity silicone oil, 40g of porous carrier (20g of fumed silica and 20g of diatomaceous earth), 20g of dispersant (low foaming fatty alcohol polyoxyethylene ether), 5g of stabilizer (sodium alginate) and 400g of deionized water; (2) Add the stabilizer to deionized water and stir at 500 rpm for 30 min to fully dissolve the stabilizer and obtain the aqueous phase; add POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low viscosity silicone oil and dispersant to the reactor and stir at 45℃ and 600 rpm for 30 min to obtain the oil phase; slowly add the oil phase to the aqueous phase, shear emulsify at 5000 rpm for 10 min, homogenize twice at 40 MPa, and then add the porous carrier in batches (5 batches, 5 min interval between batches), stir at 1500 rpm for 30 min, and then stir at 300 rpm for 10 min to obtain the high temperature resistant silicone polyether defoamer for wastewater treatment.

[0026] Example 6 Preparation of high-temperature resistant silicone polyether defoamer for wastewater treatment (1) Weigh: 100g of POSS hybrid hyperbranched silicone polyether polymer (prepared in Example 2), 80g of imidazolium ionic liquid self-emulsifying silicone polyether (prepared in Example 4), 200g of low viscosity silicone oil, 80g of porous carrier (32g of fumed silica and 48g of diatomaceous earth), 30g of dispersant (low foaming fatty alcohol polyoxyethylene ether), 8g of stabilizer (sodium alginate) and 500g of deionized water; (2) Add the stabilizer to deionized water and stir at 500 rpm for 30 min to fully dissolve the stabilizer and obtain the aqueous phase; add POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low viscosity silicone oil and dispersant to the reactor and stir at 45℃ and 600 rpm for 30 min to obtain the oil phase; slowly add the oil phase to the aqueous phase, shear emulsify at 5000 rpm for 10 min, homogenize twice at 40 MPa, and then add the porous carrier in batches (5 batches, 5 min interval between batches), stir at 1500 rpm for 30 min, and then stir at 300 rpm for 10 min to obtain the high temperature resistant silicone polyether defoamer for wastewater treatment.

[0027] Example 7 Preparation of high-temperature resistant silicone polyether defoamer for wastewater treatment (1) Weigh: 150g of POSS hybrid hyperbranched silicone polyether polymer (prepared in Example 3), 100g of imidazolium ionic liquid self-emulsifying silicone polyether (prepared in Example 4), 300g of low viscosity silicone oil, 120g of porous carrier (40g of fumed silica and 80g of diatomaceous earth), 50g of dispersant (low foaming fatty alcohol polyoxyethylene ether), 10g of stabilizer (sodium alginate) and 600g of deionized water; (2) Add the stabilizer to deionized water and stir at 500 rpm for 30 min to fully dissolve the stabilizer and obtain the aqueous phase; add POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low viscosity silicone oil and dispersant to the reactor and stir at 45℃ and 600 rpm for 30 min to obtain the oil phase; slowly add the oil phase to the aqueous phase, shear emulsify at 5000 rpm for 10 min, homogenize twice at 40 MPa, and then add the porous carrier in batches (5 batches, 5 min interval between batches), stir at 1500 rpm for 30 min, and then stir at 300 rpm for 10 min to obtain the high temperature resistant silicone polyether defoamer for wastewater treatment.

[0028] Comparative Example 1 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the POSS hybrid hyperbranched silicone polyether polymer is replaced with an equal weight of the POSS hybrid hyperbranched silicone polyether polymer prepared by the following method: The preparation method of the POSS hybrid hyperbranched silicone polyether polymer is basically the same as that in Example 2, except that the divinyl-terminated polydimethylsiloxane is replaced with an equal weight of vinyl-terminated polydimethylsiloxane (model BM-209-300).

[0029] Comparative Example 2 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the POSS hybrid hyperbranched silicone polyether polymer is replaced with an equal weight of the POSS hybrid hyperbranched silicone polyether polymer prepared by the following method: The preparation method of the POSS hybrid hyperbranched silicone polyether polymer is basically the same as that in Example 2, except that octa(dimethylsiloxy)octasesquioxane is replaced with an equal weight of polymethylhydrosiloxane.

[0030] Comparative Example 3 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the POSS hybrid hyperbranched silicone polyether polymer is replaced with an equal weight of the POSS hybrid hyperbranched silicone polyether polymer prepared by the following method: The preparation method of the POSS hybrid hyperbranched silicone polyether polymer is basically the same as that in Example 2, except that octa(dimethylsiloxy)octasesquioxane is replaced with an equal weight of 1,3,5,7-tetramethylcyclotetrasiloxane.

[0031] Comparative Example 4 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the POSS hybrid hyperbranched silicone polyether polymer is replaced with an equal weight of the POSS hybrid hyperbranched silicone polyether polymer prepared by the following method: The preparation method of the POSS hybrid hyperbranched silicone polyether polymer is basically the same as that in Example 2, except that allyl polyoxyethylene ether (number average molecular weight of 1000) is replaced with an equal weight of allyl polyoxyethylene ether (number average molecular weight of 500).

[0032] Comparative Example 5 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the POSS hybrid hyperbranched silicone polyether polymer is replaced with an equal weight of the POSS hybrid hyperbranched silicone polyether polymer prepared by the following method: The preparation method of the POSS hybrid hyperbranched silicone polyether polymer is basically the same as that in Example 2, except that allyl polyoxyethylene ether (number average molecular weight of 1000) is replaced with an equal weight of allyl polyoxyethylene ether (number average molecular weight of 1500).

[0033] Comparative Example 6 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the imidazolium ionic liquid self-emulsifying silicone polyether is replaced with an equal weight of imidazolium ionic liquid self-emulsifying silicone polyether prepared by the following method: The preparation method of imidazolium ionic liquid self-emulsifying silicone polyether is basically the same as that in Example 4, except that the low hydrogen content silicone oil in step A1 is replaced with an equal weight of end-hydrogen content silicone oil.

[0034] Comparative Example 7 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the imidazolium ionic liquid self-emulsifying silicone polyether is replaced with an equal weight of imidazolium ionic liquid self-emulsifying silicone polyether prepared by the following method: The preparation method of imidazolium ionic liquid self-emulsifying silicone polyether is basically the same as that in Example 4, except that isopentenol polyoxyethylene ether in step A1 is replaced with an equal weight of methyl allyl alcohol polyoxyethylene ether (HPEG-2400).

[0035] Comparative Example 8 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the imidazolium ionic liquid self-emulsifying silicone polyether is replaced with an equal weight of imidazolium ionic liquid self-emulsifying silicone polyether prepared by the following method: The preparation method of the imidazolium ionic liquid self-emulsifying silicone polyether is basically the same as that in Example 4, except that the epoxy-containing silicone polyether intermediate prepared in step A1 is replaced with an equal weight of the epoxy-containing silicone polyether intermediate prepared by the following method: A1: Under nitrogen protection, 150 mL of anhydrous toluene and 100 g of low-hydrogen silicone oil were added to a reaction flask and stirred until homogeneous. The mixture was heated to 75 °C, and 0.12 g of Karstedt platinum catalyst was added. 120 g of isopentenyl alcohol polyoxyethylene ether (TPEG-2400), 12 g of glycidyl methacrylate, and 0.0012 g of p-methoxyphenol were mixed thoroughly and slowly added dropwise to the reaction flask. After 1.5 h of addition, the mixture was heated to 90 °C and reacted for 5 h. The mixture was then rotary evaporated at 80 °C and -0.095 MPa to constant weight to obtain an epoxy-containing silicone polyether intermediate. A2 was performed using the same procedure as in Example 4.

[0036] Comparative Example 9 The raw material composition and preparation method of the high-temperature resistant wastewater treatment silicone polyether defoamer are basically the same as those in Example 6, except that the imidazolium ionic liquid self-emulsifying silicone polyether is replaced with an equal weight of imidazolium ionic liquid self-emulsifying silicone polyether prepared by the following method: The preparation method of imidazolium ionic liquid self-emulsifying silicone polyether is basically the same as that in Example 4, except that N-octylimidazole in step A2 is replaced with an equal weight of N-dodecylimidazole.

[0037] The low-hydrogen-content silicone oil used in the embodiments and comparative examples of this application is model BM-802-0.18, with a hydrogen content of 0.18 wt%, and is produced by Qingdao Baisenmao New Materials Co., Ltd.; the end-hydrogen-content silicone oil is model BM-202D, with a hydrogen content of 0.5 wt%, and is produced by Qingdao Baisenmao New Materials Co., Ltd.; the low-viscosity silicone oil is model WACKER®AK50; the fumed silica is model AEROSIL® R 972; the diatomaceous earth has a SiO2 content of 91.4 wt% and a D50 of 15 μm, and is produced by Baishan Xingtai Diatomaceous Earth New Materials Co., Ltd.; the sodium alginate has a molecular weight of Mw = 2.85 × 10⁻⁶. 5 Da; Divinyl-terminated polydimethylsiloxane, model BM-209-200, vinyl content 0.45wt%, viscosity 200cst / 25℃, produced by Qingdao Baisenmao New Materials Co., Ltd.; Vinyl-terminated polydimethylsiloxane, model BM-209-300, vinyl content 0.6wt%, viscosity 300cst / 25℃, produced by Qingdao Baisenmao New Materials Co., Ltd.; Polymethylhydrosiloxane, model HMS-991; Low-foaming fatty alcohol polyoxyethylene ether, model SINOPOL 1100-LF; Karstedt platinum catalyst, platinum content 2wt%.

[0038] The defoamers prepared in the examples and comparative examples were tested for dispersibility, defoaming properties, thermal stability, centrifugal oil separation rate, and stability time after dilution with 5wt% NaCl. The test results are shown in Table 1.

[0039] Dispersibility test: 1.0g of the defoamer prepared in the examples and comparative examples were added to beakers, followed by 99.0g of distilled water. The mixtures were stirred for 30 minutes, and their dispersibility was observed. The dispersibility of the defoamer in water was classified into four levels: excellent, good, medium, and poor, as shown below: Advantages: No oil spots on the solution surface; Good: The solution is milky white in color and contains a small number of fine white oil droplets; In the middle: the solution is milky white, with many white oil phase droplets, and the droplets are relatively large; Poor: The defoamer cannot be dispersed in water.

[0040] Defoaming test: 100 mL of a 0.2% sodium dodecylbenzenesulfonate aqueous solution was added to a 1 L graduated cylinder as the foaming liquid. The mixture was heated to 70°C in a water bath, and N2 was bubbled at a gas rate of 2 L / min. When the foam volume reached 500 mL, 1 g of the defoamer prepared in the examples and comparative examples was added, and timing was started simultaneously. The time taken for the foam to disappear when it was ≤10 mL was recorded. The shorter the time, the better the defoaming effect. After defoaming, bubbling continued, and the time taken for the foam height to reach 500 mL again was recorded. The longer the time, the better the foam suppression effect of the defoamer.

[0041] Thermal stability test: Weigh 1.0g of defoamer, add 100mL of deionized water, and stir magnetically for 10min to disperse it evenly to obtain the test dilution; take 20mL of the test dilution and put it into a pressure-resistant glass sample bottle, place it in an autoclave, set it to 121℃ and 0.1MPa, maintain for 30min, and take it out after it cools naturally to room temperature; evaluate the thermal stability according to the above dispersibility grade standard.

[0042] 5wt% NaCl dilution stability time test: Weigh 1.0g of defoaming agent and add it to 99.0g of 5wt% NaCl aqueous solution. Stir at 300r / min for 5min at 25℃ to ensure uniform dispersion, obtaining the diluent to be tested. Transfer the diluent to be tested to a 100mL graduated cylinder and observe it at 25℃. Observe and record the sample state every 1 hour for 72 hours. Record the time when obvious stratification, oil floating, precipitation, or flocculation occurs as the 5wt% NaCl dilution stability time. If no obvious stratification, oil floating, precipitation, or flocculation occurs within 72 hours, it is recorded as 72 hours. Obvious stratification is defined as a clear liquid or oil layer with a height ≥2mm. Obvious oil floating is defined as continuous oil spots or absorbable oil phase on the liquid surface.

[0043] Centrifugal oil separation rate test: Weigh 10.0g of defoamer and place it in a centrifuge tube. Centrifuge at 3000r / min for 30min at 25℃. After centrifugation, observe whether a transparent or semi-transparent oil phase appears in the upper layer of the centrifuge tube. Aspirate the upper oil phase and weigh it, recording it as m1. The initial mass of the defoamer is recorded as m0. If an upper oil phase, a lower sediment, and an intermediate emulsion layer appear simultaneously after centrifugation, only weigh the upper transparent or semi-transparent oil phase, excluding the aqueous clear liquid, milky white emulsion layer, or solid sediment from the count as m1. Each sample is tested in parallel three times, and the average value is taken as the test result. Calculate the centrifugal oil separation rate according to the following formula: Centrifugal oil separation rate / % = m1 / m0 × 100%; In the formula, m1 is the mass of the oil phase precipitated after centrifugation, in g; m0 is the mass of the defoamer sample before centrifugation, in g.

[0044] Table 1 Performance Test Data of Silicone Polyether Defoamer

[0045] The high-temperature resistant silicone polyether defoamer for wastewater treatment prepared by this invention exhibits excellent dispersibility, thermal stability, rapid defoaming, and long-lasting foam suppression. This is mainly due to the synergistic effect formed between the POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low-viscosity silicone oil, porous carrier, dispersant, and stabilizer. The POSS hybrid hyperbranched silicone polyether polymer contains a POSS cage-like siloxane skeleton, polydimethylsiloxane segments, and polyether segments. The POSS cage-like siloxane skeleton has high thermal stability and spatial rigidity, which can improve the structural stability and shear resistance of the defoamer under high-temperature conditions. The polydimethylsiloxane segments have low surface tension, which can promote the migration of active components to the foam membrane interface and destroy the foam membrane. The polyether segments are beneficial to improving the dispersibility of the polymer in the aqueous phase and reducing the floating and agglomeration of the silicone oil active components.

[0046] The imidazolium ionic liquid type self-emulsifying silicone polyether simultaneously contains siloxane segments, polyether segments, and imidazolium ionic liquid side groups. The siloxane segments help maintain low surface tension and defoaming ability, the polyether segments improve aqueous dispersibility, and the imidazolium ionic liquid side groups enhance the interfacial stability and anti-demulsification ability of the defoamer in saline and surfactant-containing wastewater. Specifically, N-methylimidazolium provides good hydrophilic ionic stabilization, while N-octylimidazolium introduces hydrophobic segments, facilitating the entry of active components into the foam interface, thus achieving a good balance between self-emulsifying stability and defoaming activity.

[0047] Low-viscosity silicone oil, as a rapid defoaming component, can spread quickly on the bubble film surface, reducing local surface tension and causing the bubble film to drain, thin, and rupture, thereby shortening the defoaming time. POSS hybrid hyperbranched silicone polyether and imidazolium ionic liquid self-emulsifying silicone polyether have certain compatibility and interface regulation effects on low-viscosity silicone oil, preventing the silicone oil from agglomerating or floating too quickly in the aqueous phase, thus maintaining both rapid defoaming ability and a longer defoaming time. The porous carrier, with its large specific surface area and pore structure, can adsorb and load the low-viscosity silicone oil and silicone polyether active components, allowing them to be gradually released during use. Simultaneously, the solid particles can form bridges between defoaming points in the bubble film, further improving the persistence of defoaming. Fatty alcohol polyoxyethylene ether dispersant can improve the compatibility between the oil and aqueous phases, while sodium alginate stabilizer can improve the suspension stability of the system, reducing porous carrier sedimentation and oil droplet aggregation. Through the synergistic effect of the above components, the defoamer of the present invention can maintain a good dispersion state in high-temperature wastewater systems, and has the properties of rapid defoaming, long-term foam suppression, heat resistance and stability and anti-demulsification.

[0048] In Comparative Example 1, after replacing the divinyl-terminated polydimethylsiloxane with BM-209-300, its vinyl content and viscosity were higher than those of BM-209-200 used in the examples. Under the same weight of feed, the degree of hydrosilylation reaction was more likely to be higher, resulting in an increase in the branching density and chain entanglement of the POSS hybrid silicone polyether and a decrease in chain segment mobility. This weakened its wetting, dispersion and interface regulation effects on silicone oil and porous carriers, and slowed down the migration and release of active components, which was manifested as a longer defoaming time, a shorter foam suppression time, and a decrease in salt dilution stability and centrifugal stability.

[0049] In Comparative Example 2, although polymethylhydrosiloxane contains Si-H bonds and can participate in hydrosilylation reactions, it is a chain-like hydrogen-containing siloxane and does not have a POSS cage-like rigid skeleton. The resulting polymer has lower thermal stability, salt dilution resistance, and oil separation resistance than in Example 6. However, it has good compatibility with silicone oil, so the performance decline is relatively limited.

[0050] In Comparative Example 3, octa(dimethylsiloxy)octasesquioxane was replaced with 1,3,5,7-tetramethylcyclotetrasiloxane. Although it still contains Si-H bonds and can participate in hydrosilylation reactions, it lacks the rigid POSS cage structure and has a smaller molecular size. The resulting silicone polyether structure has poor stability and dispersion stability, making the product more prone to aggregation, oil drift, or oil separation in aqueous and brine systems. Its dispersibility, thermal stability, salt dilution resistance, and centrifugal stability all decrease.

[0051] In Comparative Example 4, the number average molecular weight of allyl polyoxyethylene ether was reduced to 500. The polyether segments were shorter, making it difficult to form a sufficient hydration layer and steric hindrance stabilization effect. This resulted in a decrease in the dispersion stability of the defoamer in aqueous and brine systems. Therefore, its thermal stability, salt dilution resistance, and centrifugal stability were all lower than those of Example 6.

[0052] Comparative Example 5: The number average molecular weight of allyl polyoxyethylene ether increased to 1500. The polyether chain segments were longer and the dispersibility was relatively better. However, the hydrophilicity was too strong, which made the active component of silicone oil overly stable in the aqueous phase. The rate at which it entered the foam liquid film and released its defoaming activity was reduced. Therefore, the initial defoaming time was prolonged and the overall performance was still lower than that of Example 6.

[0053] In Comparative Example 6, after the low-hydrogen-content silicone oil was replaced by the end-hydrogen-content silicone oil, the polyether segments and imidazolium ionic liquid side groups were mainly located at the ends of the siloxane molecular chains, making it difficult to form a uniform side-chain type self-emulsifying structure, which led to a decrease in dispersion stability, interfacial migration ability and foam suppression durability.

[0054] In Comparative Example 7, replacing isopentenyl polyoxyethylene ether with methyl allyl alcohol polyoxyethylene ether resulted in a change in the end-group structure, leading to a less favorable hydrophilic / hydrophobic balance compared to Example 6. In Comparative Example 8, replacing allyl glycidyl methacrylate with glycidyl methacrylate resulted in poor compatibility between the methacrylate double bond and the hydrosilylation reaction. Furthermore, the ester group exhibited weaker hydrolytic stability in high-temperature aqueous environments compared to the ether bond structure, affecting the introduction of the imidazolium side group and structural stability, thus decreasing rapid defoaming and thermal stability. In Comparative Example 9, replacing N-octylimidazole with N-dodecylimidazole improved hydrophobicity due to the introduced long alkyl chain, resulting in a shorter initial defoaming time. However, the excessively long hydrophobic chain and relatively lower imidazolium molar amount may have disrupted the hydrophilic / hydrophobic balance of the self-emulsifying silicone polyether, leading to decreased water dispersibility, thermal stability, salt resistance, and centrifugal stability.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A high-temperature resistant silicone polyether defoamer for wastewater treatment, characterized in that, The raw materials include the following parts by weight: 5-15 parts of POSS hybrid hyperbranched silicone polyether polymer, 5-10 parts of imidazolium ionic liquid self-emulsifying silicone polyether, 15-30 parts of low viscosity silicone oil, 4-12 parts of porous carrier, 2-5 parts of dispersant, 0.5-1.0 parts of stabilizer, and 40-60 parts of deionized water; The POSS hybrid hyperbranched silicone polyether polymer is prepared by the following method: Octa(dimethylsiloxy)octasesquioxane and divinyl-terminated polydimethylsiloxane were mixed and reacted to obtain a prepolymer reaction solution; then allyl polyoxyethylene ether was added to react, and after post-treatment, POSS hybrid hyperbranched silicone polyether polymer was obtained.

2. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 1, characterized in that, The imidazolium ionic liquid self-emulsifying silicone polyether is prepared by the following method: A1: Low-hydrogen silicone oil, isopentenyl alcohol polyoxyethylene ether and allyl glycidyl ether react in the presence of a platinum catalyst to generate an intermediate; A2: Intermediate, N-methylimidazolium and N-octylimidazolium react in the presence of a proton transfer aid, and then an acidifying salting agent is added for salting to generate imidazolium ionic liquid self-emulsifying silicone polyether.

3. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 1, characterized in that, The mass ratio of the octa(dimethylsiloxy)octasesquioxane, divinyl-terminated polydimethylsiloxane, and allyl polyoxyethylene ether is 1:(0.5-2.0):(7-9).

4. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 2, characterized in that, In step A1, the mass ratio of the low-hydrogen silicone oil, isopentenyl alcohol polyoxyethylene ether, and allyl glycidyl ether is 25:30:

3.

5. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 2, characterized in that, In step A2, the mass ratio of the intermediate, N-methylimidazole, and N-octylimidazole is 100:3.2:1.

5.

6. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 2, characterized in that, The acidifying salt-forming agent is lactic acid.

7. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 1, characterized in that, The porous carrier is composed of fumed silica and diatomaceous earth in a mass ratio of 1:(1-2).

8. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 1, characterized in that, The dispersant is a low-foaming fatty alcohol polyoxyethylene ether.

9. The high-temperature resistant silicone polyether defoamer for wastewater treatment according to claim 1, characterized in that, The stabilizer is sodium alginate.

10. A method for preparing a high-temperature resistant silicone polyether defoamer for wastewater treatment as described in any one of claims 1-9, characterized in that, Includes the following steps: The stabilizer was added to deionized water and stirred to dissolve, resulting in an aqueous phase. POSS hybrid hyperbranched silicone polyether polymer, imidazolium ionic liquid self-emulsifying silicone polyether, low-viscosity silicone oil and dispersant are mixed and stirred evenly to obtain an oil phase; the oil phase is slowly added to the aqueous phase, and after shear emulsification and homogenization, it is added in batches to a porous carrier, and after stirring and filtration, a high-temperature resistant silicone polyether defoamer for wastewater treatment is obtained.

Images