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Suitable Defoamers for Reverse Osmosis Membranes

by endalton 15 Jan 2025

Suitable Defoamers for Reverse Osmosis Membranes

 

1. Overview of Reverse Osmosis Membrane Defoamers

 

   1.1 Definition and Principle of Action

 

Reverse osmosis membrane defoamers are chemical agents specifically designed to address foam issues in reverse osmosis water treatment processes. Their main components are usually a combination of modified silicone polyethers and modified silicone polyethers, which endows the defoamers with unique properties. According to relevant information, these defoamers can rapidly penetrate the surface of foam, disrupt its stability, and achieve quick defoaming effects. Moreover, they possess the ability to persistently inhibit the formation of new foam, effectively controlling it over an extended period. Additionally, these defoamers are highly compatible with the chemical components in reverse osmosis water treatment systems, without causing any additional chemical reactions, and are environmentally safe, posing no secondary pollution risks to water quality or the environment.

 

   1.2 Scope of Application and Scenarios

 

The scope of application for reverse osmosis membrane defoamers is extensive, primarily used in various industrial and chemical wastewater treatments. In practical applications, due to the use of chemical agents, water flow impacts, and changes in internal system pressure, a significant amount of foam is often generated during the reverse osmosis water treatment process. If not controlled in time, these foams can lead to poor water flow, reduced filtration efficiency of the reverse osmosis membrane, increased cleaning frequency, and higher costs. Research indicates that the use of reverse osmosis water treatment defoamers can significantly reduce or even eliminate various problems caused by foam, improving production efficiency, ensuring the stable operation of the production process, and reducing production costs and risks. For instance, in large-scale industrial wastewater treatment plants, the addition of an appropriate amount of reverse osmosis water treatment defoamers effectively resolves foam issues, making the water treatment system run more smoothly and optimizing water quality.

 

2. Classification of Defoamers

 

   2.1 Silicone-based Defoamers

 

Silicone-based defoamers are one of the commonly used types in reverse osmosis membrane treatment. Their main component is polydimethylsiloxane (silicone), which has an extremely low surface tension, allowing it to quickly spread across the gas-liquid interface, reducing the surface tension of the liquid, and thereby disrupting the stability of foam. Depending on different preparation methods, silicone-based defoamers can be divided into various forms such as water emulsion, oil-based systems, solid powders, defoaming rods, and self-emulsifying and self-dispersing types. Among them, water emulsion defoamers are suitable for defoaming in aqueous media, while oil-based defoamers are applicable to oily foaming systems. Silicone-based defoamers are widely used in multiple fields such as textile printing and dyeing, petrochemical industry, and papermaking industry. For example, in the sizing process of textile printing and dyeing, an addition of 0.2-0.25g/L of water emulsion silicone-based defoamer can effectively control the generation of foam.

 

   2.2 Polyether-based Defoamers

 

Polyether defoamers belong to the category of non-ionic surfactants and possess excellent defoaming and foam-inhibiting functions. Their main components are block copolymers of polyoxypropylene and polyoxyethylene formed in the presence of an initiator. Polyether defoamers are non-toxic, poorly soluble in water but easily soluble in organic solvents, and can be used alone or formulated into emulsions. Depending on the starting agent used in synthesis, polyether-type defoamers can be divided into polyol types, fatty acid ester types, and amine ether types. Among these, polyol and fatty acid ester types are more widely applied. Polyether defoamers are used in industries such as pharmaceuticals, fermentation, cosmetics, and pharmaceuticals, and are irreplaceable by silicone-based defoamers. For example, in the fermentation process of antibiotics, polyether defoamers can effectively control the generation of foam, ensuring the smooth progress of the fermentation process.

 

   2.3 Composite Defoamers

 

Composite defoamers are made by combining two or more different types of defoamers to enhance defoaming effects and adaptability. For example, the non-ionic T-F composite fermentation defoamer is a common type of composite defoamer. This defoamer combines the advantages of different defoamers, providing better defoaming and foam-inhibiting effects under various process conditions. The pH value of composite defoamers typically ranges from 6.0 to 9.0, making them suitable for a variety of different fermentation production processes. In practical applications, composite defoamers can be adjusted and optimized according to specific process requirements and foam characteristics to achieve the best defoaming effect.

 

3. Key Factors in Selecting Defoamers

 

   3.1 Chemical Compatibility

 

When selecting reverse osmosis membrane defoamers, chemical compatibility is a crucial consideration. The defoamer must be compatible with the various chemical agents and membrane materials used in the reverse osmosis water treatment system. Research indicates that some chemically reactive defoamers may react with other chemicals in the system, leading to a decline in agent performance or damage to the membrane materials. For example, certain highly acidic or alkaline defoamers may corrode the membrane materials, affecting their filtration performance and service life. Therefore, choosing chemically stable and highly compatible defoamers, such as those composed of modified silicone polyethers and modified silicone polyethers, can ensure the stable operation of the water treatment system and avoid additional costs and maintenance issues caused by chemical reactions.

 

   3.2 Defoaming and Foam-Inhibiting Effects

 

The core function of a defoamer is to quickly eliminate foam and prevent the formation of new foam over an extended period. In the reverse osmosis water treatment process, the generation of foam not only affects treatment efficiency but can also lead to equipment failure and a decline in water quality. According to experimental data, high-quality defoamers can eliminate a large amount of foam within a short time (usually within a few minutes) and effectively control the formation of new foam for up to 24 hours. For example, the modified silicone polyether and modified silicone polyether composite defoamer has shown excellent performance in practical applications, with a defoaming speed 30% faster than traditional defoamers and a foam-inhibiting time extended by 50%. This highly efficient defoaming and foam-inhibiting capability can significantly improve the operational efficiency of the reverse osmosis water treatment system, reducing downtime and maintenance costs caused by foam issues.

 

   3.3 Environmental and Safety Considerations

 

With the increasing awareness of environmental protection, the selection of environmentally safe defoamers has become particularly important. Defoamers should not produce harmful substances during use and should have no negative impact on the environment and human health. According to environmental department reports, some defoamers containing heavy metals or harmful chemical substances can pollute water bodies and soil after use, and may even affect human health through the food chain. Therefore, choosing defoamers that meet environmental standards and are biodegradable, such as those based on natural plant oils or produced through bio-fermentation technology, not only helps protect the environment but also meets the increasingly stringent environmental regulations. Moreover, from a safety perspective, non-toxic and low-irritation defoamers are safer and more reliable to operate and use, reducing potential health risks to operators.

 

4. Common Reverse Osmosis Membrane Defoamer Products

 

   4.1 Domestic Well-known Brand Defoamers

 

The domestic defoamer market is developing rapidly, with many brands winning market recognition for their high-quality products and good services. The following are some well-known domestic brands of reverse osmosis membrane defoamers and their characteristics:

 

- Sixin Technology: As a participant in the industry standards for silicone defoamers, Sixin Technology owns numerous defoamer product patents in China and has a large-scale defoamer production base. Its defoamer products cover a wide range of industries such as textiles, pharmaceuticals, papermaking, coatings, petroleum, cleaning, food, fertilizers, cement, building materials, and machinery processing. The product quality is stable, with excellent defoaming and foam-inhibiting performance, short usage time, and long-lasting efficiency, earning high praise from users.

 

- Shanghai Liqi Chemical Additives Co., Ltd.: Established in 2001, it is one of the leading manufacturers of emulsion-type silicone defoamers in China. The company's silicone series defoamers have been at the forefront of domestic performance and quality, widely used in papermaking, textile printing and dyeing, adhesive, petroleum processing, cleaning, fermentation, circulating water, and wastewater treatment industries, and are highly favored by customers.

 

- Yantai Hengxin Chemical Technology Co., Ltd.: A high-tech enterprise integrating the research, development, production, and sales of fine and special chemicals, with its own research and development capabilities and the right to operate imports and exports independently. The company's main products, including defoamers, are popular in more than 31 provinces, cities, and autonomous regions in China and in more than ten

 countries and regions around the world, thanks to its technical and talent advantages, a sound quality management system, and standardized management system.

 

- Guangdong Zhonglian Fine Chemical Co., Ltd.: A technology-oriented entrepreneurial enterprise, committed to becoming a technical pioneer in the fine chemical field through scientific and technological innovation. Its defoamer products are diverse, including silicone defoamers, non-silicone defoamers, polyether defoamers, mineral oil defoamers, and high-carbon alcohol defoamers, which can be widely used in multiple industry fields, breaking the foreign technical monopoly.

 

   4.2 International Well-known Brand Defoamers

 

Internationally, there are also some well-known and influential brands in the defoamer field, whose products are widely used globally. The following are some internationally renowned reverse osmosis membrane defoamer brands:

 

- Dow Chemical: Founded in 1897 in the United States, a globally renowned diversified chemical company. Its products and services are widely used in multiple fields. In the field of defoamers, Dow Chemical, with its strong research and development capabilities and technological innovation, produces defoamers that are efficient and stable, meeting the needs of different industrial water treatment processes.

 

- BASF: A chemical giant originating from Germany, with products covering multiple fields. In the production of defoamers, BASF focuses on product quality and performance. Its defoamer products excel in chemical stability and compatibility, suitable for various complex water treatment environments, effectively ensuring the normal operation of reverse osmosis membranes.

 

- BYK Additives & Instruments: Founded in 1873 in Germany, a member of the ALTANA group, and one of the world's leading suppliers of specialty chemicals. BYK's defoamer products are favored by the market for their excellent performance and wide application range, capable of quickly eliminating foam and providing long-lasting foam inhibition, offering reliable solutions for reverse osmosis water treatment.

 

- WACKER: Founded in 1914 in Germany, a world leader in the chemical industry. WACKER's defoamer products are known for their high quality and innovation. In reverse osmosis membrane water treatment, they can effectively reduce the surface tension of liquids, disrupt the stability of foam, and have good compatibility with other chemical components in the system, ensuring the efficiency and stability of the water treatment process.

 

5. Usage Methods and Precautions for Defoamers

 

   5.1 Addition Methods and Dose Control

 

The addition methods and dose control of defoamers are crucial for ensuring their effectiveness and cost-effectiveness in the reverse osmosis water treatment process. The following are several common addition methods and their corresponding dose control methods:

 

   Direct Addition

 

- Description: The defoamer is directly added to the foaming system. This method is simple to operate and is suitable for areas where foam generation is relatively concentrated. For example, in the pre-treatment stage of reverse osmosis water treatment, when the raw water enters the system, adding the defoamer directly to the raw water pool can effectively prevent the generation of foam.

 

- Dose Control: The addition amount is determined based on the volume of the foaming system and the foam generation situation. Generally, the addition amount of the defoamer can be 200ppm to 5000ppm. The specific addition amount needs to be determined according to the results of small-scale tests. For example, for a raw water pool of 1000 cubic meters, if the foam generation is relatively serious, and the optimal addition amount of the defoamer determined by small-scale tests is 1000ppm, then 1000 kilograms of defoamer need to be added.

 

   Metering Pump Continuous Drip Addition

 

- Description: The defoamer is continuously dripped into the foaming system through a metering pump. This method ensures the uniform dispersion of the defoamer, playing its continuous defoaming ability. It is suitable for systems where foam generation is relatively continuous and stable, such as in the continuous operation process of reverse osmosis water treatment. The metering pump can precisely add the defoamer to the system according to the set flow rate and frequency, ensuring the persistence of the defoaming effect.

 

- Dose Control: The parameters of the metering pump are adjusted according to the system's flow rate and foam generation rate. For example, if the flow rate of the reverse osmosis water treatment system is 100 cubic meters per hour, and the foam generation rate is 10 liters per hour, and it is determined through experiments that 0.5 grams of defoamer are needed to treat 1 cubic meter of water, then the flow rate of the metering pump should be set to 50 grams per hour to ensure the continuous supply of the defoamer and effective defoaming.

 

   Spray Head Spraying

 

- Description: The defoamer is sprayed onto the water surface through a spray head, allowing the defoamer to fully contact the foam and quickly disrupt the stability of the foam. This method is suitable for occasions where foam generation is relatively dispersed and the area is large, such as in the post-treatment stage of reverse osmosis water treatment. When the treated water enters the storage pool, the defoamer is evenly sprayed on the water surface through a spray head, which can quickly eliminate the foam and ensure the stability of the water quality.

 

- Dose Control: The spraying amount is determined based on the spraying area and the foam generation situation. For example, for a storage pool with an area of 100 square meters, if the foam generation is relatively uniform, and it is determined through experiments that 0.1 liters of defoamer are needed per square meter, then 10 liters of defoamer need to be prepared for spraying. At the same time, the frequency and amount of spraying can be adjusted in time according to the speed of foam generation and the defoaming effect.

 

   Importance of Dose Control

 

Accurately controlling the dose of the defoamer can not only ensure the defoaming effect but also avoid waste and possible side effects. Over-dosing of the defoamer may lead to excessive residual chemical substances in the water treatment system, affecting the water quality and even potentially damaging the reverse osmosis membrane. On the other hand, insufficient dosage cannot effectively control the foam, affecting the water treatment efficiency and equipment operation. Therefore, determining the optimal dosage through small-scale tests and adjusting it in time according to the actual operation is the key to the effective application of the defoamer.

 

   5.2 Storage and Handling

 

The correct storage and handling methods are crucial for maintaining the performance of the defoamer and extending its service life. The following are the precautions for the storage and handling of the defoamer:

 

   Storage Conditions

 

- Temperature: The defoamer should be stored in an environment with a suitable temperature, generally recommended to be between 5and 30. Too high or too low temperatures may affect the performance of the defoamer. For example, some silicone-based defoamers may solidify at low temperatures, and at high temperatures, they may accelerate decomposition, leading to a decline in defoaming effect.

 

- Humidity: The defoamer should be stored away from humid environments. High humidity may cause the defoamer to absorb moisture, affecting its dispersibility and stability. It is recommended to control the relative humidity of the storage environment to below 60%.

 

- Light Exposure: Strong sunlight may cause photochemical reactions in the chemical components of the defoamer, destroying its structure and reducing the defoaming effect. Therefore, the defoamer should be stored in a cool, shaded place, such as in a dark corner of a warehouse or shielded with shading materials.

 

   Packaging and Sealing

 

- Packaging Materials: The defoamer is usually packaged in plastic drums. Plastic drums have good chemical stability and sealing properties, which can effectively prevent the defoamer from deteriorating due to contact with the external environment. During storage, it is necessary to ensure that the packaging drum is intact without leakage or damage.

 

- Sealing: After each use, the packaging drum should be sealed in time to prevent moisture, impurities, and other substances in the air from entering the drum and affecting the quality of the defoamer. For defoamers that have been opened but not used up, sealing tape or special sealing caps can be used to seal the opening to ensure its sealing.

 

   Pre-use Handling

 

- Stirring Uniformly: Before using the defoamer, it should be stirred evenly. Since the defoamer may separate or settle during storage, stirring evenly can ensure the uniform distribution of its effective components and achieve the best defoaming effect. When stirring, manual stirring rods or electric stirrers can be used, and the defoamer should be stirred at a certain speed and direction until it reaches a uniform state.

 

- Dilution: Depending on the usage requirements and the properties of the defoamer, dilution may sometimes be necessary. When diluting, an appropriate diluent should be chosen, such as water or a specific organic solvent, and diluted according to a certain ratio. The diluted defoamer should be used as soon as possible to avoid performance degradation due to long-term storage. For example, for some water-based defoamers, they can be diluted with

 water at a ratio of 1:10 and then added for use.

 

   Disposal of Waste

 

- Environmental Disposal: After use, the defoamer may produce certain waste. The disposal of this waste should follow environmental principles to avoid polluting the environment. For biodegradable defoamers, they can be disposed of according to local environmental requirements through biological degradation; for non-biodegradable defoamers, they should be handed over to qualified environmental disposal agencies for professional disposal, such as incineration, landfill, etc.

 

- Safety Precautions: When handling defoamer waste, appropriate safety precautions should be taken, such as wearing gloves, masks, goggles, etc., to avoid direct contact between the waste and the human body, preventing harm to the health of the operators. At the same time, it is necessary to ensure good ventilation during the disposal process to prevent the accumulation of harmful gases.

 

6. Market Status and Development Trends of Defoamers

 

   6.1 Market Size and Growth Trends

 

The market for reverse osmosis membrane defoamers is showing a steady growth trend along with the rapid development of the water treatment industry. According to data from Forward Industry Research Institute, the scale of China's reverse osmosis membrane market was about 11.6 billion yuan in 2023, and the market size of defoamers, as an important auxiliary chemical, has also expanded accordingly. Globally, the market for reverse osmosis membrane defoamers is also growing, and it is expected that by 2029, the global reverse osmosis membrane industry market size will exceed 6.5 billion US dollars, and the defoamer market will also benefit from this.

 

In China, with the strengthening of environmental protection policies and the increasing prominence of water scarcity issues, the application of reverse osmosis water treatment technology is becoming more and more widespread, directly driving the growth of the defoamer market demand. Especially in the fields of industrial wastewater treatment and seawater desalination, there is an urgent need for efficient and environmentally friendly defoamer products. In addition, with the improvement of domestic enterprises' water quality requirements and the attention to production efficiency and cost control, the usage of defoamers is also increasing.

 

In terms of market distribution, coastal areas and economically developed regions have a more concentrated demand for reverse osmosis membrane defoamers. These areas have developed industries and a large demand for water treatment, and the requirements for the performance and quality of defoamers are also higher. For example, provinces such as Guangdong, Shandong, and Jiangsu, with their strong industrial foundations and numerous water treatment facilities, have become the main consumer markets for defoamers.

 

   6.2 Technological Innovation and Product Upgrades

 

With the continuous progress of science and technology and the increasing diversification of market demand, technological innovation and product upgrades in reverse osmosis membrane defoamers have become an important trend in the development of the industry.

 

   Development of New Defoamers

 

- Environmental-friendly Defoamers: With the increasing awareness of environmental protection, the research and production of environmental-friendly defoamers have become a focus. These defoamers do not produce harmful substances during use, have no negative impact on the environment and human health, and have good biodegradability. For example, defoamers based on natural plant oils or produced through bio-fermentation technology are not only environmentally friendly but also meet the increasingly strict environmental regulations.

 

- High-efficiency Composite Defoamers: In order to improve the defoaming effect and adaptability, researchers have compounded different types of defoamers to prepare new types of composite defoamers. These defoamers combine the advantages of various defoamers and can play a better defoaming and foam-inhibiting effect under different process conditions. For example, the non-ionic T-F composite fermentation defoamer has a wide pH value range and is suitable for a variety of different fermentation production processes.

 

- Intelligent Defoamers: Using advanced material science and chemical engineering technology, intelligent defoamers that can automatically adjust the defoaming effect according to the foam generation situation have been developed. These defoamers can realize intelligent perception and response to foam through special chemical structures or nanotechnology, improving the defoaming efficiency and economy.

 

   Improvement of Product Performance

 

- Defoaming Speed and Foam-inhibiting Durability: By optimizing the chemical formula and preparation process of the defoamer, the defoaming speed and foam-inhibiting durability have been improved. For example, the modified silicone polyether and modified silicone polyether composite defoamer has shown excellent performance in practical applications. Its defoaming speed is 30% faster than traditional defoamers, and the foam-inhibiting time is extended by 50%. This highly efficient defoaming and foam-inhibiting ability can significantly improve the operational efficiency of the reverse osmosis water treatment system, reducing downtime and maintenance costs caused by foam issues.

 

- Chemical Compatibility: Strengthening the research on the chemical compatibility of defoamers with various chemical agents and membrane materials in the reverse osmosis water treatment system to ensure that the defoamer does not have a negative impact on other components in the system during use. For example, choosing chemically stable and highly compatible defoamers, such as those composed of modified silicone polyethers and modified silicone polyethers, can ensure the stable operation of the water treatment system and avoid additional costs and maintenance problems caused by chemical reactions.

 

- Stability and Durability: Improving the stability and durability of the defoamer to maintain good performance under different environmental conditions. For example, by adding special stabilizers or using advanced packaging technology, the shelf life of the defoamer can be extended, reducing the performance degradation caused by deterioration during storage and transportation.

 

   Expansion of Application Fields

 

- Seawater Desalination: With the increasing shortage of global water resources, seawater desalination has become an important way to solve the freshwater crisis. The application of reverse osmosis membrane defoamers in the seawater desalination process is also becoming more and more widespread. Special defoamers suitable for seawater environment have been developed to effectively improve the efficiency and quality of seawater desalination.

 

- Biomedical Field: In the biomedical field, the requirements for water quality are extremely high, and reverse osmosis water treatment technology is widely used in the production of pharmaceutical water. Therefore, the requirements for the purity and safety of defoamers are also stricter. Defoamers that meet the standards of the biomedical industry have been developed to meet the strict water quality requirements of this field, ensuring the quality and safety of drug production.

 

- Electronic Industry: The demand for ultra-pure water in the electronic industry is increasing, and the application of reverse osmosis water treatment technology in this industry is also becoming more and more widespread. Special defoamers with high purity and low impurity content have been developed to effectively remove foam from water, ensuring the production quality of ultra-pure water and meeting the production needs of the electronic industry.

 

7. Case Analysis of Defoamers in Reverse Osmosis Membrane Applications

 

   7.1 Successful Application Cases

 

In a thermal power plant's intermediate water treatment plant in the north, since its establishment in 2007, the influent water source has been the Class A water discharged from the sewage treatment plant. The workshop is equipped with 4 sets of first-stage reverse osmosis systems, each with 175 membrane elements, designed to produce 100t/h of water. Among them, System I has been using the enhanced industrial reverse osmosis membrane of Times沃顿 since its commissioning in 2007. In the initial 5 years of operation, the average desalination rate of the system was above 97.5%, and the system recovery rate was above 75%, providing high-quality and stable water sources for the power plant's boiler makeup water, and has received high recognition from users. Due to the excellent performance of the PURO-I membrane elements, in 2017, the plant replaced the imported membrane elements in the second reverse osmosis system with the PURO-I membrane elements of Times沃顿. Currently, both reverse osmosis systems are running stably. The PURO-I membrane elements have a desalination rate of 99.75% and a production capacity of 10500GPD. By increasing the cross-linking degree of the desalination layer, they have a wider range of acid and alkali cleaning tolerance and enhanced anti-pollution capabilities. At present, the enhanced anti-pollution PURO-I membrane elements have accumulated a large number of application cases in fields such as power, steel, petrochemicals, municipal drinking water, electronics, and coal chemical industry.

 

   7.2 Problems Encountered and Solutions

 

In the operation of the reverse osmosis membrane system, the generation of foam is a problem that cannot be ignored. For example, in some reverse osmosis water treatment processes, due to the use of chemical agents, water flow impacts, and changes in internal system pressure, a large amount of foam is often generated. If not controlled in time, these foams can lead to poor water flow, reduced filtration efficiency of the reverse osmosis membrane, increased cleaning frequency, and

 higher costs. In response to this problem, reverse osmosis membrane cleaning defoamers have played a crucial role. They act like a silent guardian, ensuring the stable operation of the reverse osmosis membrane system and playing an irreplaceable role in many industrial and water treatment fields.

 

During the cleaning process of the reverse osmosis membrane, the cleaning agent reacts with the pollutants on the membrane surface, which may produce a large amount of gas. In addition, the proliferation of microorganisms on the membrane surface may also lead to the generation of foam due to metabolic products. The characteristics of the influent water quality also affect the generation of foam. If the influent water contains a high concentration of organic matter or certain specific ions, foam may be generated when mixed with cleaning agents. Foam can reduce cleaning efficiency, as it hinders the full contact between the cleaning agent and the membrane surface, preventing the removal of pollutants on the membrane surface. Excessive foam may also cause the cleaning equipment to malfunction, for example, foam may overflow from the cleaning tank, polluting the surrounding equipment and environment.

 

Reverse osmosis membrane cleaning defoamers can quickly adsorb on the surface of foam, reducing the surface tension of the foam liquid film. When the surface tension is reduced to a certain extent, the foam becomes unstable and ruptures. Normally, foam has a certain elasticity and can resist external disturbances to a certain extent to maintain stability. The defoamer changes the structure of the foam by interacting with its components, causing it to lose elasticity and thus promoting the rapid rupture of the foam. By using reverse osmosis membrane cleaning defoamers, the foam problem in the cleaning process can be effectively solved, improving cleaning efficiency and ensuring the performance and service life of the reverse osmosis membrane. When selecting, it is necessary to fully consider its principle of action, characteristics, and various precautions to ensure the selection of suitable reverse osmosis membrane cleaning defoamers.

 

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