CN117402346B - Composite polyether defoamer for fermentation and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of foam dispersion or prevention, and particularly discloses a composite polyether defoamer for fermentation and a preparation method thereof. The defoamer is prepared by polymerizing fatty alcohol with propylene oxide, capping with ethylene oxide to obtain polyether polyol, refining, and esterifying and grafting. Compared with the prior art, the defoaming agent prepared by the invention has the advantages of good defoaming and foam inhibiting performance, good stability, wide application range and the like.

Description

Composite polyether defoamer for fermentation and preparation method thereof

Technical Field

The invention relates to the technical field of foam dispersion or prevention, in particular to a composite polyether defoamer for fermentation and a preparation method thereof.

Background

Biological fermentation is widely used in the industries of medicine industry, food industry, energy industry, chemical industry, agriculture and the like, but foam problems often occur when using biological fermentation technology, and the foam may be caused by operation, surrounding environment, stirring and the like, and if the foam is not treated in time, the following problems are caused: 1. foam reduces the loading factor of the fermenter by an amount that affects the relevant value; 2. foam reduces the oxygen transfer system from affecting fermentation; 3. when the foam is too much, a large amount of overflow is caused, and fermentation liquor escapes from an exhaust pipeline or a shaft seal to increase the chance of bacteria contamination; 4. when the foam is severe, aeration and stirring are not performed, and thus the respiration of the cells is hindered, and metabolic abnormality or autolysis of the cells is caused, so that the use of a microbial fermentation defoamer is required.

The defoamers commonly used in the fermentation industry mainly comprise mineral oil, an organosilicon defoamer, a polyether defoamer and a polyether modified silicone oil defoamer. The polyether type defoaming agent is a water-soluble nonionic surfactant with excellent performance prepared by ring-opening polymerization of ethylene oxide and propylene oxide. Aiming at different types of foaming systems, the physical parameters such as hydrophilicity, lipophilicity, turbidity, surface tension and the like of the foaming systems can be improved by adjusting the length, the ratio and the molecular weight of ethylene oxide and propylene oxide chain segments, and the polyether defoamer can exert the inhibition performance only when the temperature of the foaming system is higher than the cloud point, so that the preparation process can adapt to the requirements of different occasions by changing the cloud point of polyether.

Chinese patent 201610373312.6 belongs to the field of chemical additives, and in particular relates to a polyether defoamer and a preparation method thereof. The material consists of the following raw materials in percentage by weight: 89% -95% of polyoxypropylene oxyethylene glycerol ether, 0.6% -2.1% of fatty high-carbon alcohol, 4% -7.7% of silicone grease and silicone oil, 0.1% -0.5% of penetrating agent, 0.1% -0.2% of catalyst, 0.1% -0.2% of dispersing agent and 0.1% -0.3% of stabilizing agent; the viscosity of the silicone oil was 260mpa.s. The defoaming agent has the advantages of good stability, high defoaming strength, low toxicity elimination, nutrition supply for hypha in the fermentation process, and high defoaming speed. The foam eliminating and inhibiting agent has excellent use effect in the industries of papermaking, fermentation, food, medicine and the like; the invention also provides a preparation method of the composite.

Chinese patent 202210706311.4 discloses a long fatty chain modified polyether, polyether defoamer composition and preparation method, wherein the long fatty chain modified polyether consists of 10-47% of long-chain fatty alcohol, 5-10% of ethylene oxide, 30-60% of propylene oxide, 10-30% of butylene oxide and 50-200ppm of bimetallic catalyst, has good spreadability on the surface of foam and penetrability to foam, and can well inhibit foam. The long fatty chain modified polyether is prepared by mixing fatty alcohols with twelve, sixteen, twenty and twenty-eight carbon atoms according to a proportion, taking the fatty alcohols as an initiator, and accessing ethylene oxide, propylene oxide and butylene oxide, and controlling the pressure, temperature and time of the reaction without harsh reaction conditions. The polyether defoamer composition prepared from the long fatty chain modified polyether, the white carbon black and the alkali catalyst has the advantages of simple preparation method, simple composition, and product performance meeting the industrial production requirement, and can be applied to white water, adhesives, printing ink and the like in the wet end of papermaking.

The polyether defoamer has wide application, is easy to disperse in water, has no toxicity or irritation, can be used in general industry and special industries such as food, fermentation, pharmacy and the like, and cannot be replaced by the silicon-containing defoamer. However, polyether defoamers still face the problems of limited use conditions, narrow application range, weak defoaming capability, low foam breaking rate and the like, and thus, improvements of the defoamers are needed.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention aims to solve the technical problem of a composite polyether defoamer for fermentation and a preparation method thereof.

The defoamer used in the fermentation process generally meets the following 4-point requirements: (1) it must be a strong surfactant with low surface tension that can be immersed and spread on the blister; (2) the dispersion is good, the foam-free water-soluble polymer has certain affinity to fermentation liquor, can be rapidly dispersed in the fermentation liquor, and acts on the foam; (3) the method has no or little influence on the growth of thalli and the synthesis and extraction of target products; (4) insoluble or insoluble, has low volatility, and has durable defoaming and foam inhibiting properties. The polyether defoamer has better compatibility with the system, but has weaker defoaming capability, the molecular structure of the defoamer is a linear structure, foam formed in the process of combining with foaming liquid is a linear structure, and the defoamer added before can be dissolved in foaming micelles. This prevents the defoamer from spreading out rapidly over the liquid surface and the defoaming ability is significantly reduced.

The polyether ester is an improved polyether defoamer, which not only maintains the advantages of high temperature resistance, easy dispersion and emulsification, low surface tension, good stability, adjustable cloud point and the like of the polyether defoamer, but also increases the lipophilicity and further reduces the hydrophilicity due to the weakening of hydrogen bonds between water molecules and polyoxyethylene chains after esterification, thereby being beneficial to reducing the surface tension, improving the activity and enhancing the defoaming capability. According to the defoaming agent obtained by esterifying and grafting the synthesized polyether polyol, the polyether ester is further grafted, so that the hydrogen bond between water molecules and polyoxyethylene chains can be weakened, the lipophilicity of the defoaming agent is increased, the surface tension is reduced, the space structure of the defoaming agent is increased, a plurality of grafted alkyl branched chains can be more easily contacted with the hydrophobic chains in the surfactant, and the multi-branched chain structure of the defoaming agent is favorable for damaging the liquid film of the surfactant. Thus, defoaming property is better. And, this larger space structure can also inhibit further occurrence of foam by preventing formation of the stable adsorption layer, thereby achieving a more stable defoaming effect.

In order to achieve the above purpose, the invention provides a preparation method of a composite polyether defoamer for fermentation, which comprises the following steps:

s1, mixing 20-30 parts by weight of palmitol, 25-35 parts by weight of stearyl alcohol and 0.5-1 part by weight of potassium hydroxide, heating to 100-120 ℃, adding 2-5 parts by weight of propylene oxide under the nitrogen atmosphere, controlling the pressure of the system to be 0.2-0.3 MPa, heating to 130-150 ℃, stirring for 1-2 hours, continuously adding 3-8 parts by weight of ethylene oxide, heating to 130-180 ℃, preserving heat, continuously aging for 20-40 minutes, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 80-100 ℃, adding 0.8-1 part by weight of water, stirring for 10-30 min, adding 0.5mol/L phosphoric acid aqueous solution to adjust pH to 5-5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain the refined polyether polyol;

s3, 15-25 parts by weight of refined polyether polyol, 0.5-1.5 parts by weight of gallic acid and 0.1-0.2 part by weight of p-toluenesulfonic acid are heated to 120-180 ℃, the acid value of the system is measured every 1h, the reaction is stopped until the acid value is basically unchanged, triethanolamine is added to adjust the pH value to be neutral after the temperature is reduced to 70 ℃, and the mixture is washed by saturated sodium chloride solution and then dried for the next step;

s4, adding the product obtained in the last step into 5-15 parts by weight of dimethyl sulfoxide, adding 1.5-2.6 parts by weight of dodecyl 1-isothiocyanate and 0.05-0.5 part by weight of dibutyltin dilaurate, stirring for 1-2 hours, adding into water at 60-80 ℃, washing, extracting and drying to obtain the product.

The invention also provides a composite polyether defoamer for fermentation, which is prepared by the method.

The invention has the beneficial effects that:

1. compared with the prior art, the defoaming agent provided by the invention has the advantages of excellent defoaming capability, excellent foam inhibition capability, good stability and lasting defoaming effect.

2. The defoaming agent has the characteristics of good stability, high defoaming speed, small consumption, no toxicity, no smell and the like due to a large space structure, and has excellent use effects of eliminating and inhibiting foam in the industries of food, papermaking, printing ink, coating, chemical industry and the like.

Detailed Description

Comparative example 1

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 400g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain the final product.

Example 1

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 400g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain refined polyether polyol;

s3, heating 1.8kg of refined polyether polyol, 80g of gallic acid and 20g of p-toluenesulfonic acid to 150 ℃, measuring the acid value of the system every 1h, stopping the reaction until the acid value is basically unchanged, cooling to 70 ℃, adding triethanolamine to adjust the pH value to be neutral, washing with saturated sodium chloride solution, and drying for the next step;

s4, adding the product of the last step into 1.2L of dimethyl sulfoxide, adding 230g of dodecyl 1-isothiocyanate and 15g of dibutyl tin dilaurate, stirring for 1h, adding into 70 ℃ water, washing, extracting and drying to obtain the product.

Example 2

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 400g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain refined polyether polyol;

s3, heating 1.8kg of refined polyether polyol, 80g of gallic acid and 20g of p-toluenesulfonic acid to 150 ℃, measuring the acid value of the system every 1h, stopping the reaction until the acid value is basically unchanged, cooling to 70 ℃, adding triethanolamine to adjust the pH value to be neutral, washing with saturated sodium chloride solution, and drying to obtain the modified polyether.

Example 3

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 400g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain refined polyether polyol;

s3, heating 1.8kg of refined polyether polyol, 133g of stearic acid and 20g of p-toluenesulfonic acid to 150 ℃, measuring the acid value of the system every 1h, stopping the reaction until the acid value is basically unchanged, cooling to 70 ℃, adding triethanolamine to adjust the pH value to be neutral, washing with saturated sodium chloride solution, and drying to obtain the product.

Example 4

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 200g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain refined polyether polyol;

s3, heating 1.8kg of refined polyether polyol, 80g of gallic acid and 20g of p-toluenesulfonic acid to 150 ℃, measuring the acid value of the system every 1h, stopping the reaction until the acid value is basically unchanged, cooling to 70 ℃, adding triethanolamine to adjust the pH value to be neutral, washing with saturated sodium chloride solution, and drying for the next step;

s4, adding the product of the last step into 1.2L of dimethyl sulfoxide, adding 230g of dodecyl 1-isothiocyanate and 15g of dibutyl tin dilaurate, stirring for 1h, adding into 70 ℃ water, washing, extracting and drying to obtain the product.

Example 5

A preparation method of a composite polyether defoamer for fermentation comprises the following steps:

s1, mixing 2.5kg of palmitol, 2.6kg of stearyl alcohol and 50g of potassium hydroxide, heating to 110 ℃, adding 500g of propylene oxide under nitrogen atmosphere, controlling the pressure in a system to be 0.25MPa, heating to 140 ℃, stirring for 1h, continuously adding 500g of ethylene oxide, heating to 150 ℃, preserving heat, continuously aging for 30min, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 90 ℃, adding 80mL of water, stirring for 30min, adding 0.5mol/L phosphoric acid aqueous solution to adjust the pH to 5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain refined polyether polyol;

s3, heating 1.8kg of refined polyether polyol, 80g of gallic acid and 20g of p-toluenesulfonic acid to 150 ℃, measuring the acid value of the system every 1h, stopping the reaction until the acid value is basically unchanged, cooling to 70 ℃, adding triethanolamine to adjust the pH value to be neutral, washing with saturated sodium chloride solution, and drying for the next step;

s4, adding the product of the last step into 1.2L of dimethyl sulfoxide, adding 230g of dodecyl 1-isothiocyanate and 15g of dibutyl tin dilaurate, stirring for 1h, adding into 70 ℃ water, washing, extracting and drying to obtain the product.

Test case

The defoaming agent prepared in the comparative example and the example is tested according to HG/T4783-2014 fatty alcohol emulsion defoaming agent, and the defoaming and foam inhibition performance of the defoaming agent on sodium dodecyl sulfate solution and papermaking white water is tested by adopting a circulating brewing method. Recording the foam height change in 900s after the sample is added, wherein the defoaming capability is expressed as foam residual rate, the foam residual rate is the ratio of the minimum foam volume to the initial foam volume, and the smaller the ratio is, the stronger the defoaming performance is; the foam inhibition capacity is expressed by the foam inhibition rate, the smaller the ratio of the foam volume to the initial foam volume is, the stronger the foam inhibition performance is, and the temperature is 40 ℃.

Table 1 results of defoaming and foam suppressing performance test of defoamer

Defoamers generally have high surface activity and can replace the blowing agents and foam stabilizers on the foam, thereby reducing the surface tension of the replaced locations. The foam system is added with the defoaming agent, so that spreading and permeation can be rapidly carried out on the surface of the liquid film of the bubble, and a plurality of areas with uneven surface tension distribution can be generated on the surface. Because of the marangoni effect, the surface tension distribution of the areas is uneven to form a surface tension gradient, and liquid at a low surface tension flows to a high surface tension, so that a liquid film at the area becomes thinner, the foaming stability is poor, further, cracking occurs, and the phenomenon of foam elimination occurs. It is apparent that the greater the surface tension gradient formed by the defoamer molecules and the foaming system, the faster the bubble collapse speed and the stronger the defoaming capability. The comparison between the comparative example and the example shows that the defoaming and foam inhibition performances of the polyether polyol are obviously improved after modification, which is probably due to the fact that the hydrogen bond between polyether and water molecules is reduced after esterification, and the introduced groups have hydrophobic and oleophilic properties, so that the surface tension of the introduced groups in the aqueous solution can be further reduced, and the effect of improving the performances is achieved. However, the saturated fatty acids used in example 3 have long hydrophobic alkyl chains compared to example 3, and thus the performance improvement is superior to example 2. However, in example 1, by further grafting the polyether ester, not only the hydrogen bond between the water molecule and the polyoxyethylene chain can be weakened, so that the lipophilicity is increased, the hydrophilicity is further reduced, the surface tension is reduced, the activity is increased, the defoaming capability is enhanced, the space structure of the defoaming agent is further increased, the grafted multiple alkyl branched chains can be more easily contacted with the hydrophobic chain in the surfactant, and the multi-branched chain structure also contributes to the damage effect on the surfactant liquid film. Thus the defoaming line is better. And, this larger space structure can also suppress further occurrence of foam by formation of the tissue-stabilizing adsorption layer, thereby achieving a more stable defoaming effect.

The difference between example 1 and examples 4 to 5 is that the molecular chain length is also prolonged when the amount of propylene oxide added is increased, which increases the space occupied by the defoamer on the interface film, thus the tendency of improving the defoaming performance, but the molecular weight is too large, which causes that the foam to be formed cannot be timely diffused to the gas-liquid interface and thus the dispersion of the gas in the foaming system cannot be prevented, so that the performance is reduced, and the amount of propylene oxide added needs to be proper to maintain the optimal performance.

The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention by one of ordinary skill in the art without undue burden. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims (2)

1. The preparation method of the defoaming agent is characterized by comprising the following steps:

s1, mixing 20-30 parts by weight of palmitol, 25-35 parts by weight of stearyl alcohol and 0.5-1 part by weight of potassium hydroxide, heating to 100-120 ℃, adding 2-5 parts by weight of propylene oxide under the nitrogen atmosphere, controlling the pressure of the system to be 0.2-0.3 MPa, heating to 130-150 ℃, stirring for 1-2 hours, continuously adding 3-8 parts by weight of ethylene oxide, heating to 130-180 ℃, preserving heat, continuously aging for 20-40 minutes, vacuumizing, degassing, cooling to room temperature, and discharging;

s2, heating the material obtained in the last step to 80-100 ℃, adding 0.8-1 part by weight of water, stirring for 10-30 min, adding 0.5mol/L phosphoric acid aqueous solution to adjust pH to 5-5.5, stirring and mixing uniformly, adding magnesium silicate, dehydrating, and filtering to obtain the refined polyether polyol;

s3, 15-25 parts by weight of refined polyether polyol, 0.5-1.5 parts by weight of gallic acid and 0.1-0.2 part by weight of p-toluenesulfonic acid are heated to 120-180 ℃, the acid value of the system is measured every 1h, the reaction is stopped until the acid value is basically unchanged, triethanolamine is added to adjust the pH value to be neutral after the temperature is reduced to 70 ℃, and the mixture is washed by saturated sodium chloride solution and then dried for the next step;

s4, adding the product obtained in the last step into 5-15 parts by weight of dimethyl sulfoxide, adding 1.5-2.6 parts by weight of dodecyl 1-isothiocyanate and 0.05-0.5 part by weight of dibutyltin dilaurate, stirring for 1-2 hours, adding into water at 60-80 ℃, washing, extracting and drying to obtain the product.

2. A composite polyether defoamer for fermentation, characterized in that the composite polyether defoamer is prepared by the method of claim 1.