Guide to the use of water-based non-silicon defoamers: scientific operation from entry to mastery

In industrial production, foam problems often lead to reduced efficiency, increased costs and even product scrapping, and water-based non-silicon defoamers have become a "weapon" to solve this problem with their environmentally friendly and efficient characteristics. However, how to use defoamers scientifically to avoid "ineffective addition" or "overuse"? This article will reveal the "code" for the correct use of water-based non-silicon defoamers from basic principles to practical skills.

1. Know your "weapon": the core characteristics of water-based non-silicon defoamers

Before use, you need to clarify its three key characteristics:

Ingredients and safety

Water-based non-silicon defoamers are mainly polyethers, mineral oils, plant extracts, etc., do not contain silicone, and are suitable for food, medicine, and environmentally sensitive fields. It is necessary to confirm whether the product has passed relevant certifications (such as FDA, NSF).

Defoaming mechanism

Defoaming is achieved through three steps of "penetration-membrane rupture-liquid discharge": rapid penetration of the foam membrane, reducing surface tension to rupture the membrane, and accelerating liquid discharge to prevent foam regeneration.

Applicable scenarios

Applicable to water-based systems (such as coatings, papermaking, and water treatment), but in strong acid, strong alkali or high temperature (>80°C) environments, special models that are heat-resistant and acid-resistant need to be selected.

2. Preparation before use: Accurate diagnosis of foam problems

Blindly adding defoamers may be counterproductive, and the following steps need to be analyzed:

Locate the source of foam

Physical stirring: high-speed dispersion, pumping and other operations introduce air.

Chemical reaction: such as fermentation gas production and aeration process in sewage treatment.

Raw material characteristics: surfactants, resins and other ingredients are prone to foaming.

Evaluate the hazards of foam

Determine whether the foam affects production (such as blocking pipes, reducing coating quality) or is just "visual interference".

Select matching models

Choose acid-resistant, high-temperature-resistant or food-grade defoamers according to the system pH value, temperature, and composition. For example, the papermaking white water system requires an alkali-resistant type, and food fermentation requires a non-toxic grade.

3. Scientific addition: four-step operation method

Step 1: Determine the amount of addition

Basic dosage: usually 0.05%-0.5% of the total amount of the system (such as 0.5-5kg for 1 ton of paint).

Dynamic adjustment: 

Determine the optimal dosage through small tests. For example, gradually add to the paint until there are no shrinkage holes, no pinholes, and the coating gloss meets the standard.

Avoid excessive dosage: excessive dosage may cause shrinkage holes, stratification or affect product performance (such as decreased adhesion of the paint).

Step 2: Choose the time to add

Preventive addition: Add before stirring and reaction to form a "protective film" to inhibit foam generation.

Remedial addition: When foam has been generated, add small amounts in batches and stir (such as adding once every 1 hour in sewage treatment).

Key nodes: Focus on adding during the high-incidence period of foam such as the paint grinding stage and the peak period of fermentation gas production.

Step 3: Optimize the addition method

Direct addition: Dilute the defoamer (usually diluted 1-10 times) and slowly pour it into the system to avoid excessive local concentration.

Continuous dripping: Defoamer is continuously injected through a metering pump (such as papermaking white water system) to maintain a stable concentration.

Spraying method: Spray defoamer at the place where foam accumulates (such as the top of the fermentation tank) to quickly eliminate surface foam.

Step 4: Mixing and dispersion

Low-speed stirring: Stir at 50-100 rpm for 10-15 minutes after adding to avoid destroying the stability of the system.

Avoid shearing: High-speed shearing may destroy the molecular structure of the defoamer and reduce the effect.

4. Practical cases: Key points of operation in different industries

Case 1: Water-based paint production

Problem: A large amount of foam is generated during high-speed dispersion, resulting in shrinkage of the coating.

Solution:

Add 0.3% of polyether defoamer during the grinding stage and disperse for 10 minutes.

Add 0.1% defoamer during the paint mixing stage to ensure that there are no bubbles remaining.

Effect: The glossiness of the coating is increased by 15%, and the defective rate is reduced from 8% to 1%.

Case 2: Sewage treatment aeration tank

Problem: Foam accumulation in the activated sludge process hinders aeration efficiency.

Solution:

Choose an alkali-resistant mineral oil-based defoamer, dilute it 5 times and drip it continuously through a metering pump.

The amount added per hour is 0.02% of the water flow rate.

Effect: Foam height is reduced by 70%, and aeration efficiency is increased by 18%.

Case 3: Food fermentation tank

Problem: Yeast fermentation gas production causes foam overflow.

Solution:

Use food-grade polyether defoamer and add 0.1% at the beginning of fermentation.

In the middle and late stages, according to the foam situation, spray 0.05% defoamer every 2 hours.

Effect: Fermentation cycle is shortened by 10%, and there is no foam overflow accident.

5. Common misunderstandings and solutions

Misunderstanding 1: The defoamer has poor effect and blindly increases the dosage

Reason: It may be due to poor compatibility or improper addition time.

Solution: Check the system pH value and temperature, or replace the matching model; change to preventive addition.

Myth 2: The system becomes turbid or stratified after defoaming

Reason: The defoamer reacts with the system components.

Solution: Choose a model with better compatibility, or add a dispersant to improve stability.

Myth 3: The effect decays after long-term use

Reason: The defoamer is consumed by the system components or degraded by microorganisms.

Solution: Regularly add defoamers, or choose special models that resist microbial degradation.

6. Safety and environmental protection: details that cannot be ignored

Operation protection

Wear protective clothing, gloves and goggles to avoid direct contact with the skin or inhalation.

Operate in a ventilated environment and stay away from fire sources (some mineral oil-based defoamers are flammable).

Waste disposal

Wastewater containing defoamers must be treated to meet the standards before being discharged to avoid affecting aquatic organisms.

Empirical containers must be treated as hazardous wastes and cannot be discarded at will.

Conclusion: From "empiricism" to "scientific management"

The use of water-based non-silicon defoamers is not "one-and-done", but requires systematic management in combination with system characteristics, process parameters and environmental requirements. Through accurate diagnosis, scientific addition and continuous optimization, enterprises can not only solve the foam problem, but also improve production efficiency, reduce costs, and achieve a win-win situation of green and efficiency. In the future, with the development of intelligent monitoring technology, the use of defoaming agents will be more accurate and efficient, injecting new vitality into Industry 4.0.