High-efficiency defoaming agent, preparation method and application thereof

Abstract

The application discloses a kind of high-efficiency defoaming agent and its preparation method and application, it is related to fine chemical technology field.The high-efficiency defoaming agent contains higher alcohol, the carbon number of above-mentioned higher alcohol is 31~45;And, modified organosilicon, above-mentioned modified organosilicon is prepared by chemical modification to low hydrogen-containing silicone oil by silane addition reaction to cypressene alcohol;The conversion rate of above-mentioned silane addition reaction is >93.5%.The high-efficiency defoaming agent provided by the application has better defoaming and bubble inhibition capacity, and the defoaming, bubble inhibition active effect time is longer, and the defoaming agent stability is higher, while more obvious inhibition wastewater aerobic activated sludge tank's foaming trend, with wide application range.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a high-efficiency defoamer, its preparation method, and its application. Background Technology

[0002] Wastewater treatment is the process of purifying wastewater to meet the water quality requirements for discharge into a water body or for reuse. Classified by source, wastewater treatment is generally divided into industrial wastewater treatment and domestic wastewater treatment. Industrial wastewater includes industrial wastewater, agricultural wastewater, and medical wastewater, while domestic wastewater is wastewater generated in daily life, referring to a complex mixture of various forms of inorganic and organic matter. Due to the complex composition of wastewater, especially domestic wastewater, a large amount of foam is generated during treatment, severely affecting wastewater treatment efficiency; therefore, defoamers need to be added.

[0003] Defoamers with an O / W emulsion structure are widely used as foam inhibitors in wastewater treatment processes. Known wax-based O / W emulsion defoamers are manufactured as follows: the effective components of room-temperature solids and liquids, such as higher alcohols, hydrocarbons, and fatty acid esters, are heated and melted, emulsified and dispersed under normal pressure, and then cooled. Chinese patent CN104225965 proposes an emulsion-type organosilicon defoamer using high-boiling silicone oil as one of the raw materials, reducing production costs and providing a reasonable treatment channel for high-boiling byproducts of organosilicon monomers. While polyvinyl alcohol (PVA) is used as a thickener, it generates foam during water dissolution, reducing production capacity and affecting product quality and usability. CN103830938 proposes using nonionic surfactants as emulsifiers, such as Tween-60, Span-40, or polyether silicone oil, which have high emulsifying ability but poor alkali resistance. Therefore, there is an urgent need for a defoamer with stable and durable defoaming performance. Summary of the Invention

[0004] The purpose of this invention is to provide a high-efficiency defoamer, its preparation method, and its application. This high-efficiency defoamer has better defoaming and foam-suppressing abilities, longer duration of defoaming and foam-suppressing activity, higher stability, and can more significantly inhibit the foaming trend of aerobic activated sludge tanks in wastewater, thus having a wide range of applications.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A highly efficient defoamer contains a higher alcohol having a carbon number of 31-45; and,

[0007] The modified organosilicon is prepared by chemically modifying low-hydrogen silicone oil with cedarwood phenolic alcohol via a hydrosilylation reaction; the conversion rate of the hydrosilylation reaction is >93.5%. This invention uses cedarwood phenolic alcohol to modify low-hydrogen silicone oil via a hydrosilylation reaction to prepare the modified organosilicon. When applied to defoamers, it synergistically enhances the defoaming and foam-suppressing abilities of the defoamer when combined with other components. It exhibits lower surface tension, rapid defoaming, long foam-suppressing time, good stability, no demulsification or oil floating phenomenon, easy dispersion in water, no precipitation, good adaptability, and low dosage. Simultaneously, it significantly inhibits the foaming tendency of aerobic activated sludge tanks in wastewater, prolongs the foam-suppressing activity time of membrane scale inhibitors, and ensures the normal operation of the petrochemical wastewater treatment process. The reason for this may be that by chemically modifying organosiloxanes with cypress olefins, substituents are introduced onto the silicon atoms in their backbone, further enhancing their physical / chemical properties while maintaining their inherent performance. The resulting modified organosilicon exhibits better surface activity and lower surface tension, leading to defoamers with superior defoaming and foam-suppressing properties. Furthermore, the introduction of polar and inactive hydrocarbon groups into the organosilicon chain structure enhances the stability of the modified organosilicon and prolongs the foam-suppressing activity duration of the antifoaming agent in membrane scale inhibitors. This invention provides a defoamer with excellent comprehensive performance and broad application prospects. The preparation process is simple and easy to operate, making it more suitable for industrial production.

[0008] In one specific embodiment, the high-efficiency defoamer has an O / W type emulsion structure.

[0009] In one specific embodiment, the hydrogen content of the low-hydrogen silicone oil is 0.05~0.30%.

[0010] In one specific embodiment, the high-efficiency defoamer also contains polydimethylsiloxane and polyether.

[0011] In one specific embodiment, the high-efficiency defoamer also contains an emulsifier.

[0012] In one specific embodiment, the emulsifier is selected from at least one of Span and Tween.

[0013] The present invention further discloses the above-mentioned high-efficiency defoamer, comprising: by weight, 20-30 parts modified organosilicon, 10-20 parts polydimethylsiloxane, 10-20 parts higher alcohol, 8-14 parts polyether, 3-6 parts silica, 2-4 parts emulsifier, and 40-60 parts distilled water.

[0014] The preparation method of the above-mentioned modified organosilicon includes:

[0015] Add cypress phenol to toluene, then add platinum catalyst, and heat to 75-85°C under nitrogen protection. Then start adding a toluene solution containing low hydrogen-containing silicone oil dropwise. After the addition is complete, measure the Si-H content at regular intervals. When the content remains unchanged, it is the endpoint of the reaction. Distill under reduced pressure, add a mixture of n-hexane / tetrahydrofuran to precipitate 2-4 times, rotary evaporate, and vacuum dry overnight at 75-85°C to obtain modified organosilicon.

[0016] In a specific embodiment, the mass ratio of cedarwood phenol to toluene is 1:35~50; the concentration of the toluene solution containing low-hydrogen silicone oil is 0.02~0.03 g / mL; the amount ratio of cedarwood phenol to low-hydrogen silicone oil is n(C=C):n(Si-H)=1~1.2:1; and the amount of platinum catalyst is 30~45 ppm (calculated as Pt).

[0017] In one specific embodiment, the volume ratio of n-hexane to tetrahydrofuran in the n-hexane / tetrahydrofuran mixture is 18~22:1.

[0018] More preferably, the polyether in the high-efficiency defoamer is replaced by a novel polyether; the novel polyether is obtained by polymerization of ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane. This invention uses ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as monomers to prepare a polyether with a novel structure through a copolymerization reaction. When applied to defoamers, it can further reduce the surface tension of the defoamer, enhance its defoaming and foam-suppressing abilities, and further improve the stability and dispersibility of the defoamer in water. This enhances the defoaming performance in aerobic activated sludge tanks and prolongs the duration of defoaming and foam-suppressing activity. The reason for this may be that the molecular chain structure of the novel polyether prepared in this invention may increase the ability of the molecules to cover the surface, and the increased volume of the alkyl hydrophobic groups increases the density of hydrophobic groups on the surface, thereby effectively reducing surface tension, enhancing the defoaming and foam-suppressing performance of the defoamer, and improving its stability.

[0019] More specifically, the method for synthesizing the above-mentioned novel polyether includes:

[0020] Initiator n-butanol and catalyst potassium hydroxide are mixed, vacuumed and purged with high-purity nitrogen 2-4 times, while simultaneously dehydrating. Then, a uniformly mixed mixture of ethylene oxide, methylthiopropylene oxide and 1,4-bis[(glycidoxy)methyl]cyclohexane is added for polymerization. The reaction pressure is set to less than 0.4 MPa, the reaction temperature is 110-120℃, and the reaction time is 5-8 h. Then, a neutralizing agent is added to neutralize to neutrality. Finally, an appropriate amount of adsorbent is used, followed by vacuum dehydration, drying, and filtration to obtain a novel polyether.

[0021] In a specific embodiment, the amount of initiator n-butanol used is 3.5~5wt% of the total amount of polymerizable monomers; the amount of catalyst potassium hydroxide used is 2~3wt‰ of the total amount of polymerizable monomers; and the molar ratio of ethylene oxide, methylthiopropylene oxide and 1,4-bis[(glycidoxy)methyl]cyclohexane is 1:0.2~0.5:0.2~0.4.

[0022] In one specific embodiment, the molecular weight of the novel polyether is 1000~3000.

[0023] The preparation method of the above-mentioned high-efficiency defoamer includes: taking modified organosilicon, polydimethylsiloxane, higher alcohol and polyether, heating to 80~90℃, stirring for 20~40min, adding silica, slowly heating to 110~130℃, stirring for 1~3h; cooling to 80~100℃ and adding emulsifier and stirring at high speed, then adding water, mixing and stirring at 10000~12000r / min for 30~50min to obtain the high-efficiency defoamer.

[0024] This invention further discloses the application of the above-mentioned high-efficiency defoamer in the field of water treatment.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention utilizes cypress phenol to modify low-hydrogen silicone oil via hydrosilylation reaction. When applied to defoamers, it synergistically enhances the defoaming and foam-suppressing abilities of the defoamer when combined with other components. It exhibits lower surface tension, rapid defoaming, long foam-suppressing time, good stability, and easy dispersibility in water. Simultaneously, it significantly inhibits the foaming tendency in aerobic activated sludge tanks and prolongs the foam-suppressing activity time of membrane scale inhibitors, ensuring the normal operation of petrochemical wastewater treatment processes. Furthermore, this invention uses ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as monomers to prepare a novel polyether structure through copolymerization. When applied to defoamers, this further reduces the surface tension of the defoamer, enhances its defoaming and foam-suppressing abilities, and further improves its stability and dispersibility in water. This enhances the defoaming performance of aerobic activated sludge tanks and further prolongs its activity time. This invention provides a defoamer with excellent comprehensive performance and broad application prospects. The preparation process is simple and easy to operate, which is more conducive to industrial production.

[0027] Therefore, the present invention provides a high-efficiency defoamer, its preparation method and application. The high-efficiency defoamer has better defoaming and foam-suppressing capabilities, and the defoaming and foam-suppressing activity lasts longer. The defoamer has higher stability and can more significantly inhibit the foaming trend of aerobic activated sludge tanks in wastewater, and has a wide range of applications. Attached Figure Description

[0028] Figure 1 The infrared spectral test results of the modified organosilicon and low-hydrogen silicone oil in Example 1 of this invention;

[0029] Figure 2 The infrared spectral test results are for the novel polyether in Example 5 of this invention. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to specific embodiments:

[0031] The platinum catalyst used in the embodiments of the present invention is chloroplatinic acid, and the hydrogen content of the low-hydrogen silicone oil used is 0.16%, both of which are commercially available; the polyether used in the embodiments of the present invention is polyether L61, which was purchased from Nantong Aonuo Chemical Co., Ltd.

[0032] Example 1:

[0033] A high-efficiency defoamer comprises, by weight: 26 parts modified organosilicon, 14 parts polydimethylsiloxane, 15 parts higher alcohol (n-dodecyl alcohol), 10 parts polyether, 4 parts silica, 3 parts emulsifier, and 50 parts distilled water. The emulsifier is Span 60.

[0034] Preparation of modified organosilicon:

[0035] Toluene was added to cylindrical alcohol at a mass ratio of 1:45, followed by a platinum catalyst (37 ppm, calculated as Pt). Under nitrogen protection, the mixture was heated to 82°C, and a toluene solution containing 0.025 g / mL low-hydrogen silicone oil was added dropwise, ensuring that the ratio of cylindrical alcohol to low-hydrogen silicone oil was n(C=C):n(Si-H) = 1.1:1. After the addition was complete, the Si-H content was measured at regular intervals. The reaction endpoint was reached when the Si-H content remained constant. The mixture was then distilled under reduced pressure, and a hexane / tetrahydrofuran (20:1, v / v) mixture was added to precipitate the product three times. The product was then rotary evaporated and vacuum dried overnight at 80°C to obtain modified organosilicon. The conversion rate of the hydrosilylation reaction was 94.2%.

[0036] Preparation of the above-mentioned high-efficiency defoamer: Take modified organosilicon, polydimethylsiloxane, higher alcohol and polyether, heat to 85°C, stir for 30 min, add silica, slowly heat to 125°C, stir for 2 h; cool to 95°C, add emulsifier and stir at high speed, then add water, mix and stir at 12000 r / min for 40 min to obtain the high-efficiency defoamer.

[0037] Example 2:

[0038] A high-efficiency defoamer comprises, by weight: 22 parts modified organosilicon, 18 parts polydimethylsiloxane, 11 parts higher alcohol (n-dodecyl alcohol), 9 parts polyether, 3 parts silica, 2 parts emulsifier, and 42 parts distilled water. The emulsifier is Tween 80.

[0039] The preparation method of modified organosilicon differs from that in Example 1 in that: the ratio of cypress phenolic alcohol to low-hydrogen silicone oil is n(C=C):n(Si-H) = 1.2:1; the amount of platinum catalyst is 32 ppm (calculated as Pt); and the conversion rate of hydrosilylation reaction is 95.2%.

[0040] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 1.

[0041] Example 3:

[0042] A high-efficiency defoamer comprises, by weight: 28 parts modified organosilicon, 12 parts polydimethylsiloxane, 10 parts higher alcohol (n-dodecyl alcohol), 13 parts polyether, 4 parts silica, 4 parts emulsifier, and 58 parts distilled water. The emulsifier is a mixture of Span 60 and Tween 80 in a mass ratio of 1:1.

[0043] The preparation method of the modified organosilicon differs from that in Example 1 in that: the ratio of cypress phenol to low-hydrogen silicone oil is n(C=C):n(Si-H) = 1.05:1; the amount of platinum catalyst is 41.6 ppm (calculated as Pt); and the conversion rate of the hydrosilylation reaction is 93.9%.

[0044] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 1.

[0045] Example 4:

[0046] A high-efficiency defoamer comprises, by weight: 27 parts modified organosilicon, 14 parts polydimethylsiloxane, 13 parts higher alcohol (n-dodecyl alcohol), 11 parts polyether, 5 parts silica, 3 parts emulsifier, and 55 parts distilled water. The emulsifier is selected from at least one of Span and Tween.

[0047] The method for preparing modified organosilicon differs from that in Example 1 in that: the ratio of cypress phenolic alcohol to low-hydrogen silicone oil is n(C=C):n(Si-H) = 1.15:1; the amount of platinum catalyst is 37.6 ppm (calculated as Pt); and the conversion rate of the hydrosilylation reaction is 94.1%.

[0048] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 1.

[0049] Example 5:

[0050] The difference between this high-efficiency defoamer and Example 1 is that it uses a novel polyether prepared in this example to replace the polyether.

[0051] The preparation method of the modified organosilicon is the same as that in Example 1.

[0052] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 1.

[0053] Synthesis of novel polyethers:

[0054] Initiator n-butanol and catalyst potassium hydroxide were mixed, evacuated, and purged with high-purity nitrogen 2-4 times while dehydrating. Ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane were then added for polymerization. The reaction pressure was set to less than 0.4 MPa, the reaction temperature to 115℃, and the reaction time to 6 h. A neutralizing agent was then added to neutralize the mixture. The resulting product was then dehydrated under vacuum using an appropriate amount of adsorbent, dried, and filtered to obtain a novel polyether with a molecular weight of 1189.5. In the specific preparation process, the amount of initiator n-butanol used was 4.2 wt% of the total monomers; the amount of catalyst potassium hydroxide used was 2.6 wt‰ of the total monomers; and the molar ratio of ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane was 1:0.36:0.27.

[0055] Example 6:

[0056] The difference between this high-efficiency defoamer and Example 5 is that it uses low-hydrogen silicone oil instead of modified organosilicon.

[0057] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 5.

[0058] The synthesis of the novel polyether was the same as in Example 5.

[0059] Example 7:

[0060] The difference between this highly efficient defoamer and Example 6 is that the novel polyether was prepared in this example.

[0061] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 6.

[0062] The synthesis of the novel polyether differs from that in Example 6 in that: the amount of initiator n-butanol used is 3.8 wt% of the total amount of polymerizable monomers; the amount of catalyst potassium hydroxide used is 2.1 wt‰ of the total amount of polymerizable monomers; the molar ratio of ethylene oxide, methylthiopropylene oxide and 1,4-bis[(glycidoxy)methyl]cyclohexane is 1:0.3:0.3; and the molecular weight of the novel polyether is 1137.4.

[0063] Example 8:

[0064] The difference between this highly efficient defoamer and Example 6 is that the novel polyether was prepared in this example.

[0065] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 6.

[0066] The synthesis of the novel polyether differs from that in Example 6 in that: the amount of initiator n-butanol used is 4.7 wt% of the total amount of polymerizable monomers; the amount of catalyst potassium hydroxide used is 2.9 wt‰ of the total amount of polymerizable monomers; the molar ratio of ethylene oxide, methylthiopropylene oxide and 1,4-bis[(glycidoxy)methyl]cyclohexane is 1:0.45:0.25; and the molecular weight of the novel polyether is 1208.8.

[0067] Comparative Example 1:

[0068] The difference between this high-efficiency defoamer and Example 1 is that it uses low-hydrogen silicone oil instead of modified organosilicon.

[0069] The preparation of the above-mentioned high-efficiency defoamer is the same as in Example 1.

[0070] Experimental Example 1:

[0071] Infrared characterization

[0072] The tests were performed using the potassium bromide pellet method with a Thermo Nicolet 67 Fourier transform infrared spectrometer, with a wavelength range of 4000–500 cm⁻¹. -1 .

[0073] The modified organosilicon and low-hydrogen silicone oil prepared in Example 1 were subjected to the above tests, and the results are as follows: Figure 1 As shown in the figure. Analysis of the figure reveals that, compared to the infrared spectrum of low-hydrogen-content silicone oil, the infrared test results for modified organosilicon show a higher concentration in the 3300~3500 cm⁻¹ range. -1 The characteristic absorption peak of -OH appears in the range, at 2165 cm⁻¹. -1 The characteristic absorption peaks of the nearby Si-H bonds have largely disappeared, and the absorption peaks are now mostly in the 2800~3000 cm⁻¹ range. -1 The presence of enhanced intensity of characteristic absorption peaks for methyl and methylene groups within the specified range indicates that the modified organosilicon in Example 1 was successfully prepared.

[0074] The novel polyether prepared in Example 5 was subjected to the above tests, and the results are as follows: Figure 2 As shown in the figure. Analysis of the figure reveals that in the infrared spectrum of the novel polyether, 3486 cm⁻¹... -1 The area around the -OH group has a characteristic absorption peak, 2800~3000 cm⁻¹. -1 The characteristic absorption peaks for methyl and methylene groups are within the range of 1100 cm⁻¹. -1 The area near the characteristic absorption peak of COC is 657 cm⁻¹. -1 The presence of a characteristic absorption peak of the CS bond nearby indicates that the novel polyether in Example 5 was successfully prepared.

[0075] Conversion rate calculation:

[0076] Conversion rate % = (Products of the reaction / Products before the reaction) × 100%

[0077] Experimental Example 2:

[0078] Defoamer performance characterization

[0079] 1. Determination of foam suppression performance

[0080] Take 100 mL of foaming solution (obtained by dissolving 10 g of sodium dodecylbenzenesulfonate in deionized water and transferring it to a 1 L volumetric flask and making up to the mark), add it to a 500 mL graduated cylinder, then place it into a glass tube connected to a nitrogen cylinder, add 0.01 g of defoamer sample, adjust the gas flow rate to 500 mL / min, and start timing. Stop when the foam volume reaches 500 mL. The time obtained is the foam suppression time.

[0081] 2. Defoaming performance determination

[0082] Take 500 mL of the foam, remove the glass tube, and record the time it takes for the foam to completely disappear as the defoaming time.

[0083] 3. Stability determination

[0084] Centrifugation stability test: Take 30 mL of emulsion sample and put it into a 50 mL centrifuge tube. Centrifuge at 5000 r / min for 60 min and observe whether layering and oil floating phenomena occur in the centrifuge tube.

[0085] Water dispersibility test: Add 0.5g of defoamer sample to 100g of deionized water, shake repeatedly, and observe the dispersion of the defoamer sample in water. If the sample disperses quickly in water and no oily substance appears on the water surface, it indicates excellent dispersibility in water; if the sample disperses relatively quickly in water and no oily substance appears in the water, it indicates good dispersibility in water; if the sample disperses slowly in water and flocculent material appears on the water surface, it indicates average dispersibility in water; if the sample does not disperse in water and a large amount of flocculent material appears on the water surface, it indicates poor dispersibility in water.

[0086] The high-efficiency defoamers prepared in Comparative Example 1 and Examples 1-8 were subjected to the above tests, and the results are shown in Table 1:

[0087] Table 1. Performance Characterization Test Results of Defoamer

[0088] sample Defoaming time / min Defoaming time / s Centrifugal stability Water dispersibility Comparative Example 1 15.4 12.3 Layering generally Example 1 20.8 7.4 Unlayered better Example 2 20.4 7.8 Unlayered better Example 3 20.9 7.6 Unlayered better Example 4 20.2 7.3 Unlayered better Example 5 24.7 4.6 Unlayered Excellent Example 6 19.1 8.9 Unlayered better Example 7 20.9 9.1 Unlayered better Example 8 19.5 8.8 Unlayered better

[0089] Analysis of the data in Table 1 shows that the defoaming time of the high-efficiency defoamer prepared in Example 1 is significantly shorter than that of Comparative Example 1, while the foam suppression time is longer. This indicates that using cypress olefin-modified organosilicon as one of the defoamer components, in combination with other components, can effectively enhance the defoaming performance of the defoamer, significantly shortening the defoaming time and significantly extending the foam suppression time. The effect of Example 5 is significantly better than that of Example 1, and the effect of Example 6 is better than that of Comparative Example 1. This indicates that using the novel polyether obtained by polymerizing ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as one of the components of the defoamer can further enhance the defoaming and foam suppression capabilities of the defoamer.

[0090] Meanwhile, the centrifugal stability and water dispersibility of the high-efficiency defoamer prepared in Example 1 were significantly better than those in Comparative Example 1, indicating that using cypress olefin-modified organosilicon as one of the defoamer components, in combination with other components, can effectively enhance the stability of the defoamer and significantly improve its water dispersibility. The effect of Example 5 was significantly better than that of Example 1, and the effect of Example 6 was better than that of Comparative Example 1, indicating that using a novel polyether obtained by polymerizing ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as one of the components of the defoamer can further enhance the stability of the defoamer and further improve its water dispersibility.

[0091] Experimental Example 3:

[0092] Interfacial tension measurement

[0093] Add a 0.8 g / L concentration of defoamer sample to the deionized water. Measure the inner diameter of the beaker with calipers. Then add water to the caliper reading and measure the water temperature. Calculate the water density based on the temperature. Next, place a capillary tube and a U-shaped glass rod with a wire attached into the beaker, securing them with a test tube clamp. Control the capillary tube's position relative to the beaker's axis so that one end of the wire is just touching the water surface. Simultaneously, use calipers to read the water surface position and the liquid level position inside the capillary tube. Finally, calculate the surface tension using the following formula:

[0094] Surface tension (mN / m) = (ρgh)(h+3 / r) / 2

[0095] In the formula, ρ represents the density of water, in g / cm³. 3 ; r represents the inner diameter of the capillary tube, mm; h is the height of the water column in the capillary tube.

[0096] The high-efficiency defoamers prepared in Comparative Example 1 and Examples 1-8 were subjected to the above tests, and the results are shown in Table 2:

[0097] Table 2. Surface tension characterization test results of defoamer

[0098] sample Minimum surface tension (mN / m) Comparative Example 1 24.6 Example 1 21.4 Example 2 21.7 Example 3 21.1 Example 4 21.5 Example 5 19.3 Example 6 22.6 Example 7 22.8 Example 8 22.4

[0099] Analysis of the data in Table 2 shows that the minimum surface tension of the high-efficiency defoamer prepared in Example 1 is significantly lower than that of Comparative Example 1, and the foam suppression time is longer than that of Comparative Example 1. This indicates that using cypress olefin-modified organosilicon as one of the defoamer components, in combination with other components, can effectively reduce the surface tension of the defoamer and improve its defoaming performance. The effect of Example 5 is significantly better than that of Example 1, and the effect of Example 6 is better than that of Comparative Example 1. This indicates that using the novel polyether obtained by polymerizing ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as one of the components of the defoamer can further reduce the surface tension of the defoamer and improve its defoaming and foam suppression performance.

[0100] Experimental Example 4:

[0101] Characterization of foam elimination performance in aerobic activated sludge tanks for wastewater

[0102] Take 200 mL of a mixture of aerobic activated sludge and oil refinery wastewater (concentration of activated sludge is 5000 mg / L), add it to a 500 mL graduated cylinder, and use an air pump to aerate it until the foam height is 300 mL (defoaming time > 30 s). Then add 4 mL of defoamer sample and record the defoaming time. Continue to aerate and record the foam height generated within 30 min.

[0103] Method for adding defoamer samples: Add defoamer at the point where the sludge from the secondary sedimentation tank is returned to the aerobic activated sludge tank. Try to choose a point with a relatively low organic matter content as the addition point to ensure that the defoamer can be fully and evenly mixed in the sludge, reduce the dosage, and prolong the contact time between the defoamer and the sludge-wastewater mixture.

[0104] The high-efficiency defoamers prepared in Comparative Example 1 and Examples 1-8 were subjected to the above tests, and the results are shown in Table 3:

[0105] Table 3. Test results of defoaming performance of aerobic activated sludge

[0106] sample Defoaming time / s Foam height / mL Comparative Example 1 14.6 43.5 Example 1 9.3 27.4 Example 2 9.6 27.8 Example 3 9.2 27.5 Example 4 9.5 27.1 Example 5 4.3 15.7 Example 6 9.8 31.6 Example 7 9.6 31.2 Example 8 9.9 31.9

[0107] Analysis of the data in Table 3 shows that the defoaming time required for defoaming treatment of aerobic activated sludge with the high-efficiency defoamer prepared in Example 1 is significantly shorter than that in Comparative Example 1, and the foam height within half an hour is significantly lower than that in Comparative Example 1. This indicates that using cypress olefin-modified organosilicon as one of the components of the defoamer, in combination with other components, can effectively enhance the defoaming effect of the defoamer in the aerobic activated sludge tank of wastewater, and has a longer foam-suppressing activity. The effect of Example 5 is significantly better than that of Example 1, and the effect of Example 6 is better than that of Comparative Example 1. This indicates that using the novel polyether obtained by polymerizing ethylene oxide, methylthiopropylene oxide, and 1,4-bis[(glycidoxy)methyl]cyclohexane as one of the components of the defoamer can further enhance the defoaming effect of the defoamer in the aerobic activated sludge tank of wastewater and prolong the foam-suppressing time of the defoamer.

[0108] The conventional techniques described in the above embodiments are existing technologies known to those skilled in the art, and therefore will not be described in detail here.

[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A highly efficient defoamer, comprising a higher alcohol having a carbon number of 31-45; and, The modified organosilicon is prepared by chemically modifying low-hydrogen silicone oil with cypress ol via a hydrosilylation reaction; the conversion rate of the hydrosilylation reaction is >93.5%; the hydrogen content of the low-hydrogen silicone oil is 0.05~0.30%; and the high-efficiency defoamer also contains polydimethylsiloxane and polyether. The preparation of modified organosilicon includes: Add cedarwood phenolate to toluene, then add platinum catalyst. Under nitrogen protection, heat to 75-85℃ and begin dropwise addition of a toluene solution containing low-hydrogen silicone oil. After the addition is complete, measure the Si-H content at regular intervals. The reaction endpoint is reached when the content remains constant. Distill under reduced pressure, add a hexane / tetrahydrofuran mixture to precipitate 2-4 times, rotary evaporate, and vacuum dry overnight at 75-85℃ to obtain modified organosilicon. The mass ratio of cedarwood phenolate to toluene is 1:35-50; the concentration of the toluene solution containing low-hydrogen silicone oil is 0.02-0.03 g / mL; the ratio of cedarwood phenolate to low-hydrogen silicone oil is n(C=C):n(Si-H) = 1-1.2:

1.

2. The high-efficiency defoamer according to claim 1, characterized in that: The high-efficiency defoamer has an O / W type emulsion structure.

3. The high-efficiency defoamer according to claim 1, characterized in that: The high-efficiency defoamer also contains an emulsifier.

4. The high-efficiency defoamer according to claim 3, characterized in that: The emulsifier is selected from at least one of Span and Tween.

5. A method for preparing the high-efficiency defoamer according to claim 1, comprising: Take modified organosilicon, polydimethylsiloxane, higher alcohol and polyether, heat to 80~90℃, stir for 20~40min, add silica, slowly heat to 110~130℃, stir for 1~3h; cool to 80~100℃, add emulsifier and stir at high speed, then add water, mix and stir at 10000~12000r / min for 30~50min to obtain a high-efficiency defoamer.

6. The application of the high-efficiency defoamer according to claim 1 in the field of water treatment.

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