Surfactants in cleaning products: the different types and their properties

Abwaschwasser mit Reinigungsmittel

Surfactants are the hidden heroes of the cleaning world. These remarkable molecules play a crucial role in a wide range of products, from household cleaners to personal care products. But what exactly are surfactants and how do they work? That's exactly what you'll learn in the following article.

What are surfactants?

Surfactants are chemical compounds known as surface-active substances . They have the unique ability to reduce the surface tension between two liquids or between a liquid and a solid. This property allows surfactants to act as effective cleaning agents and emulsifiers in cleaning products. They are also known as detergents. Generally speaking, they can be divided into two main categories.

  • Natural surfactants: These are made from renewable raw materials.
  • Synthetic surfactants: They are usually made from raw materials such as crude oil.

The structure of a surfactant typically includes a hydrophobic (water-repelling) part and a hydrophilic (water-attracting) part. The hydrophobic part binds to dirt and oil , while the hydrophilic part binds to water . This combination allows surfactants to disperse dirt particles and grease in water so they can be removed during rinsing or washing .

Person washing hands

In cleaning products, surfactants are crucial for efficiency. Not only do they help to dissolve dirt and grease, but they also allow these contaminants to remain suspended in the washing solution and not settle back on the clean surface. Through the way they work, surfactants make a significant contribution to effectively cleaning surfaces and improving the appearance and hygiene of textiles , dishes and other cleaned items. But what types of surfactants are there and how do they differ?

Surfactants: Structure and classification of detergent substances

Surfactants are complex molecules. They have their own structure that determines their effectiveness in cleaning products. They can be divided into different categories based on their molecular structure and charge properties. Here is an overview of their structure and classification:

Structure of surfactants

Hydrophobic (water-repellent) part: This part of the surfactant molecule is usually a long hydrocarbon chain. It has an aversion to water but an affinity to oils and fats, which allows it to bind to dirt .

Hydrophilic (water-loving) part: This is the part of the molecule that attracts water and can dissolve well in water . It often consists of a group of atoms that carry a positive, negative, or no charge.

Classification of surfactants

Surfactants are classified based on the charge properties of their hydrophilic portion. The following four types are most commonly used in cleaning products:

  • Anionic surfactants: These surfactants are negatively charged in the hydrophilic part. Due to their strong cleaning power and good foaming, anionic surfactants are often used in detergents and dishwashing detergents
  • Cationic surfactants: These surfactants have a positive charge in the hydrophilic part. They often have a disinfectant effect and are used in fabric softeners and some cleaning products.
  • Non-ionic surfactants: Their hydrophilic part carries no charge. They are milder than anionic surfactants and are often used in products for sensitive skin or surfaces.
  • Amphoteric surfactants: Depending on the pH value of the medium, they can carry both a positive and a negative charge. Amphoteric surfactants are particularly mild and skin-friendly and are therefore often used in personal care products.

With the information mentioned, you have already gained a small overview of the world of surfactants. In order to expand your knowledge and be fully informed the next time you shop, we would like to take a closer look at the individual types of surfactants.

What are anionic surfactants?

Anionic surfactants are a class of surfactants in which the hydrophilic (water-loving) part of the molecule is negatively charged. This negative charge is created when the molecule dissociates in an aqueous solution, making it able to interact with water and clean effectively. The hydrophobic (water-repelling) part of these surfactants is usually made up of long hydrocarbon chains that bind to fats and oils.

Examples of anionic surfactants in cleaning agents

  • Sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS): These surfactants are commonly used in detergents, dishwashing detergents and many personal care products such as shampoos and shower gels.
  • Alkylbenzenesulfonates: A major ingredient in many detergents and all-purpose cleaners.
  • Soaps (fatty acid salts): These soaps are biodegradable and are very often a component of environmentally friendly cleaning products.

Anionic surfactants: advantages and disadvantages

Advantages of anionic surfactants

  • Strong cleaning power: Anionic surfactants are particularly effective at removing grease and dirt.
  • Good foaming: They produce plenty of foam that helps pick up and carry away dirt particles.

Kitchen sponge used to clean a surface

  • Cost efficiency: Many anionic surfactants are relatively inexpensive to produce.

Possible disadvantages of anionic surfactants

  • Skin irritation: Some anionic surfactants (SLS) can cause irritation on sensitive skin.
  • Environmental impact: Some older types are difficult to degrade. If they get into the outside world, they can cause environmental problems.
  • Difficulties in hard water: Anionic surfactants can react with the minerals in hard water and lose their cleaning efficiency.

Biodegradable and skin-friendly variants are always preferable. This reduces the negative impact on the environment.

What are non-ionic surfactants?

Non-ionic surfactants are a type of surface-active substance characterized by the fact that their hydrophilic part does not carry an electrical charge. They achieve their cleaning effect by lowering the surface tension of water, which makes it easier to mix with oils and fats. Without a charge, non-ionic surfactants tend to be mild and less reactive with other chemical substances, which makes them very versatile.

Examples of non-ionic surfactants in cleaning agents

  • Alcohol ethoxylates: Often used in detergents and all-purpose cleaners because they effectively remove dirt while being gentle on surfaces and skin.
  • Alkylphenol ethoxylates: Used to be a component of many cleaning products. However, due to environmental concerns, they have now increasingly been replaced by more environmentally friendly alternatives.

Non-ionic surfactants: advantages and disadvantages

Advantages of non-ionic surfactants

  • Mild cleaning: They are less aggressive than other types of surfactants and therefore gentle on sensitive surfaces and the skin.
  • Less sensitivity to water hardness: Non-ionic surfactants are less susceptible to the formation of insoluble salts in hard water, which improves their cleaning efficiency.
  • Stability: They are stable across a wide pH spectrum and can be used in a variety of cleaning products.

Possible disadvantages of non-ionic surfactants

  • Lower foaming: Compared to anionic surfactants, they often produce less foam, which may be perceived as less effective in some cleaning contexts.
  • Environmental impact: Some older types, such as alkylphenol ethoxylates, are known for their harmful environmental impacts, although they are increasingly being replaced by more environmentally friendly alternatives.

If you value environmental compatibility and gentle cleaning, then most cleaning products that contain non-ionic surfactants are generally a good choice. Because they offer an optimal balance between cleaning performance and environmental responsibility .

What are cationic surfactants?

Cationic surfactants are a category of surface-active substances whose hydrophilic head carries a positive charge. These positively charged molecules tend to bind to negatively charged surfaces, such as many types of dirt and microbial cell walls. This property makes them effective disinfectants and fabric softeners.

Examples of cationic surfactants in cleaning agents

  • Quaternary ammonium compounds: These are often found in disinfectants because, in addition to their ability to remove dirt, they also have antimicrobial effects.
  • Benzalkonium chloride: A widely used cationic surfactant used in disinfectants, sanitary cleaners and personal care products.

Cationic surfactants: advantages and disadvantages

Advantages of cationic surfactants

  • Antimicrobial properties: They can kill or inhibit the growth of bacteria and other microorganisms, making them important ingredients in disinfectants.
  • Softening effect: Used in fabric softeners, they give textiles a pleasant feel and reduce static charge.
  • Efficiency in low concentrations: Cationic surfactants are often effective even in low doses.

Yellow warning sign "Cleaning in Progress"

Possible disadvantages of cationic surfactants

  • Environmental concerns: They are often less biodegradable than other surfactants and can harm aquatic ecosystems.
  • Potential toxicity: Some cationic surfactants can be toxic to humans and animals at higher concentrations.
  • Limitations of use: Cationic surfactants are not compatible with anionic surfactants as they can neutralize each other.

Cleaning products containing cationic surfactants are not recommended . Where they are necessary, attention should be paid to more environmentally friendly formulations and safer applications in order to minimize environmental impact and health risks.

What are amphoteric surfactants?

Amphoteric surfactants, also known as zwitterionic surfactants, are characterized by their ability to carry both positive and negative charges depending on the pH of the solution in which they are found. They have a unique molecular structure that allows them to change their charge. At a low pH they behave more like cationic surfactants and at a high pH they resemble anionic surfactants.

Examples of amphoteric surfactants in cleaning agents

  • Betaines, especially cocamidopropyl betaine: Often used in shampoos and body washes and valued for their skin compatibility and mild cleansing properties.
  • Amine oxides, such as lauramine dipropylamine oxide: Found in household cleaners and personal care products.

Amphoteric surfactants: advantages and disadvantages

Benefits of amphoteric surfactants

  • Mild cleansing: Amphoteric surfactants are considered to be particularly mild, which makes them ideal for use in products for sensitive skin.
  • Good skin tolerance: They rarely cause irritation and are therefore a popular choice for baby products and care products for sensitive skin.

Heart-shaped foaming sponge

  • Adaptability: Their ability to change their charge makes them versatile and effective across a wide pH range.

Possible disadvantages of amphoteric surfactants

  • Cost: Amphoteric surfactants can be more expensive to produce than anionic or nonionic surfactants.
  • Foaming: Although they have good cleaning properties, they may not always produce the desired foam that some consumers associate with cleaning power.
  • Compatibility: Their amphoteric nature can add complexity to product formulation as they can react both synergistically and antagonistically with other surfactants.

The properties mentioned make amphoteric surfactants particularly versatile and gentle in use, making them a popular choice in personal care products and for sensitive surfaces. They are able to clean effectively while being less irritating to the skin or material surfaces than other surfactant types .

How can you tell which surfactants are harmful when shopping?

To find out which surfactants you might want to avoid, it's important to look at the ingredient list. The following tips will help you make a good decision:

  1. Pay attention to the ingredients: Look at the list of ingredients on the packaging. You can often find surfactants under terms that end in "-sulfate", "-betaine" or "-ethoxylate".
  1. Avoid certain surfactants: If you have sensitive skin or want to be environmentally conscious, you should avoid surfactants like sodium lauryl sulfate (SLS) or sodium laureth sulfate (SLES) as these can be considered irritants. Avoid surfactants that are not biodegradable or come from petroleum-based sources.
  1. Pay attention to seals and certificates: Look for environmental or organic seals. They make it clear that a product was manufactured without aggressive surfactants.
  1. Manufacturer information: Find out about the surfactants used and their origin on the manufacturer’s website.
  1. Monitor your skin's reactions: If your skin becomes irritated after using a product, check which surfactants it contains and avoid them in the future.
  1. Choose milder alternatives: There are also gentler alternatives . These include sugar surfactants, which are often used in sustainable products.

As you have already noticed, you don't have to be a chemist to find your way through the product jungle. With the help of the tips mentioned, you can easily find products that are a good fit for your skin and your ecological awareness.

Synthetic surfactants vs. natural surfactants: which is the better choice?

If you have to choose between synthetic and natural surfactants, products with green surfactants such as sugar-based ones are always the better choice . Natural surfactants are obtained from renewable sources and are environmentally friendly as they tend to be more biodegradable.

Unlike their synthetic counterparts, which are often petroleum-based and can cause irritation on sensitive skin, natural surfactants are kinder to the skin. They offer effective cleaning power without compromising on environmental and skin-friendliness. Therefore, choosing products with green surfactants is not only a conscious choice for health, but also supports a sustainable lifestyle.

Conclusion: Surfactants and their properties

Surfactants are essential ingredients in the world of cleaning products that play a central role due to their ability to reduce surface tension. They allow water to interact with oils and fats, effectively removing dirt and grease from various surfaces. Their versatility allows the right surfactant to be found for every application, from powerful degreasing household cleaners to gentle personal care products.

FAQ: Questions & Answers

What are surfactants?

Surfactants are chemical compounds used in cleaning products to reduce the surface tension of liquids. This allows them to mix water with oils and fats, allowing the removal of dirt and grease from surfaces.

Are surfactants harmful to the environment?

Some conventional surfactants can be harmful to the environment, but there are many biodegradable and environmentally friendly alternatives. It is important to look for products with sustainably sourced and biodegradable surfactants.

How do surfactants affect water quality?

Surfactants can affect water quality, especially if they are not fully biodegradable. However, eco-friendly surfactants are designed to break down quickly in the environment without leaving harmful residues.

Can surfactants be used in organic cleaning products?

There are surfactants that are obtained from natural sources and are suitable for use in biological cleaning products. These are often of plant origin and meet ecological standards.

How to choose the right detergent with surfactants?

When buying cleaning products, it is important to pay attention to the type of surfactants and their origin. Products containing biodegradable and environmentally friendly surfactants are preferable, especially for households with children, pets or sensitive people.