Differences Between Anionic Cationic and Nonionic Surfactants

Aug. 06, 2024

Differences Between Anionic Cationic and Nonionic Surfactants

Difference Between Anionic Cationic and Nonionic Surfactants

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The key difference between anionic cationic and nonionic surfactants is that anionic surfactants contain negatively charged functional groups, and cationic surfactants contain positively charged functional groups, whereas nonionic surfactants have no net electrical charge.

The term surfactant refers to surface-active agents. That means, the surfactants can reduce the surface tension between two substances. For example, two substances can be two liquids, a gas and a liquid or a liquid and a solid. There are three main types of surfactants as anionic, cationic and nonionic surfactants. These three types differ from each other according to the electrical charge of the compound.

1. Overview and Key Difference
2. What are Anionic Surfactants
3. What are Cationic Surfactants
4. What are Nonionic Surfactants
5. Side by Side Comparison &#; Anionic Cationic vs Nonionic Surfactants in Tabular Form
6. Summary

What are Anionic Surfactants?

Anionic surfactants are a type of surface-active agents that contain negatively charged functional groups in the head of the molecule. Such functional groups include sulfonate, phosphate, sulfate and carboxylates. These are the most common surfactants we use. For example, soap contains alkyl carboxylates.

What are Cationic Surfactants?

Cationic surfactants are a type of surface-active agents that contain positively charged functional groups in the head of the molecule. Most of these surfactants are useful as antimicrobials, antifungal agents, etc. It is because they can disrupt the cell membranes of bacteria and viruses. The most common functional group we can find in these molecules is ammonium ion.

What are Nonionic Surfactants?

Nonionic surfactants are a type of surface-active agents that have no net electrical charge in their formulations. That means, the molecule does not undergo any ionization when we dissolve it in water. Furthermore, they have covalently bonded oxygen-containing hydrophilic groups. These hydrophilic groups bind with hydrophobic parent structures when the surfactant is added to a sample. The oxygen atoms in these compounds can cause the hydrogen bonding of the surfactant molecules.

Since the hydrogen bonding is affected by temperature, temperature increasing decreases the dissolution of these surfactants. Furthermore, there are two major forms of nonionic surfactants according to the differences in their hydrophilic groups as follows:

Polyoxyethylene

Polyhydric Alcohols

What is the Difference Between Anionic Cationic and Nonionic Surfactants?

There are three main types of surfactants as anionic, cationic and nonionic surfactants. The key difference between anionic cationic and nonionic surfactants is that anionic surfactants contain negatively charged functional groups, and cationic surfactants contain positively charged functional groups, whereas nonionic surfactants have no net electrical charge. Examples for anionic surfactants include the chemical compounds containing sulfonate, phosphate, sulfate and carboxylates. The cationic surfactants mainly contain ammonium cation. There are two major types of nonionic surfactants as polyoxyethylene and polyhydric alcohols.

The following infographic summarizes the difference between anionic cationic and nonionic surfactants.

Summary &#; Anionic Cationic vs Nonionic Surfactants

The term surfactant is used to name surface-active agents. There are three main types of surfactants as anionic, cationic and nonionic surfactants. The key difference between anionic cationic and nonionic surfactants is that anionic surfactants contain negatively charged functional groups, and cationic surfactants contain positively charged functional groups, whereas nonionic surfactants have no net electrical charge.

Reference:

1. Helmenstine, Anne Marie. &#;What Is a Surfactant?&#; ThoughtCo, Feb. 11, , Available here.
2. Helmenstine, Anne Marie. &#;Understanding How Detergents and Surfactants Work and Clean.&#; ThoughtCo, Feb. 11, , Available here.
3. Williams, Jesse J. &#;Formulation of Carpet Cleaners.&#; Handbook for Cleaning/Decontamination of Surfaces, , pp. 103&#;123., doi:10./b978--0/-8.

Image Courtesy:

1. &#;Surfactant&#; By Major measure &#; Own work (Public Domain) via Commons Wikimedia
2. &#;Diagram of Surfactant 2&#; By BQUB19-PDonatiu &#; Own work (CC BY-SA 4.0) via Commons Wikimedia

Anionic Surfactants

Anionic surfactants are surface actives that ionize negative charges in water. In the production of surfactants, anionic surfactants occupy the maximum variety and quantity.

Anionic surfactants are one of the most frequently employed surfactants and make up about 41% of all consumed surfactants. Anionic surfactants are not only the main active components of daily chemical detergents and cosmetics, but also have a wide range of uses in many other industrial fields. Anionic surfactants can play an important role in both industrial and civil applications.

Figure. 1. Schematic structure of anionic surfactants molecule

Types of Anionic Surfactants

According to compositions and structures, anionic surfactants fall into three categories:

Soap surfactants: Soap surfactant is an advanced fatty acid salt with hydrocarbon chain between C11 to C18. Soap surfactants that are frequently used include stearic acid, oleic acid and lauric acid. According to the different metal ions (Mn+), soap surfactants can be divided into alkali metal soaps, alkaline earth metal soaps and organic amine soaps.

Sulfate surfactants: Sulfate surfactants can be mainly divided into sulfated oils and higher fatty alcohols. The chemical structure of sulfate surfactant can be shown as ROSO4-M+, in which the higher alcohol hydrocarbon chain R is between C12 and C18. Sulphated castor oil, commonly known as turkish red oil, is a representative type of sulphated oil. It is a yellow or orange viscous liquid with a slight odor. It can be mixed with water and is a non-irritating detergent and wetting agent. Soaps wash the skin and can also be used to solubilize volatile oils or water-insoluble bactericides.

Sulfonate Surfactants: Sulfonate surfactants mainly include aliphatic sulfonates, sulfoaryl sulfonates and sulfonaphthalene sulfonates. The general structure of the molecule is ROSO3-M+. Their water solubility, resistances to calcium and magnesium salt are slightly less soluble than sulfuric acid.

Applications

Anionic surfactants are a wide group of chemical compounds which have a large number of applications in household cleaning detergents, personal-care products, textiles, paints, polymers, pesticides, pharmaceuticals, mining, oil recovery, and the pulp and paper industries, agriculture, cosmetic industry, sewage treatment industry, textile industry and daily chemical industry.

Agriculture: It is reported that anionic surfactants which are used as pesticide emulsifiers can reduce the amount of emulsifier from 20% to 3%. This will help to improve the chemical stability of pesticides, reduce costs and pollution, and increase the efficiency of utilization. Anionic surfactants are added to insecticides, rust removers and plant growth regulators to improve soils. Anionic surfactants can improve pesticide efficiency by multiple mechanisms. In particular anionic surfactants can increase the foliar uptake of herbicides, growth regulators, and defoliants. Mixed with insecticides, rust removers and plant growth regulators, anionic surfactants can also be used as soil conditioners.

Cosmetic industry: Anionic surfactants have been widely used in cosmetics industry and in our daily life due to their pharmacological and toxicological safety. Anionic surfactants are mainly used as emulsifier, solubilizer, wetting agent and effective component synergist.

Sewage treatment industry: Anionic surfactants can be used for the treatment of domestic sewage and organic wastewater. Anionic surfactants show cationicity in both acidic and alkaline media. This makes it possible to flocculate precipitates with negatively charged aerosol particles. As the king of new flocculants, anionic surfactants have extensive sources, good effect of treating sewage and simple equipment for subsequent sludge disposal, so they are widely used in sewage treatment field, such as the treatment for grain alcohol wastewater, papermaking wastewater, brewery wastewater, monosodium glutamate wastewater, sugar wastewater, high organic content wastewater, feed wastewater, textile printing and dyeing wastewater.

Textile industry: A large amount of anionic surfactants are used in the textile dyeing and printing industry every year. For example, anionic surfactants with cleaning effect are used in the pretreatment process, and anionic surfactants with percolation effect are used in the dyeing and finishing processes. In addition, some functional products such as leveling agents and fixing agents are also anionic type.

Daily chemical industry: Anionic surfactants are widely used in our daily life. The most common soap consisting of sodium stearate is a kind of anionic surfactants. Anionic products have the characteristics of smooth, high foam and low price, which can reduce the cost of the detergents and other products, while improving the product transparency.

Contact us to discuss your requirements of Anionic Vs Nonionic. Our experienced sales team can help you identify the options that best suit your needs.

Reference

Ewa Olkowska;Marek Ruman;Anna Kowalska;Żaneta Polkowska: Determination of Surfactants in Environmental Samples. Part II. Anionic Compounds [J]. Ecological Chemistry and Engineering S, ,20(2).

Anionic surfactants

The anionic surfactant can undergo dissociation when being dissolved in water with the part of surface activity exhibiting hydrophobic anion effects. Typical anionic surfactants include soaps, alkylbenzene sulfonates, alkyl sulfonates, alkyl sulfonates, alkyl sulfates, salts of fluorinated fatty acids, silicones, fatty alcohol sulfates, polyoxyethylene fatty alcohol ether sulfates, α-olefin sulfonate, polyoxyethylene fatty alcohol phosphates ether, alkyl alcohol amide, alkyl sulfonic acid acetamide, alkyl succinate sulfonate salts, amino alcohol alkylbenzene sulfonates, naphthenates, alkylphenol sulfonate and polyoxyethylene monolaurate. Anionic surfactants are generally insoluble at low temperatures. If the concentration continued to increase, they will reach a threshold limit, then precipitating out active agent of hydration. Upon increased water temperature at a certain temperature, due to the dissolving of the micelles, leaving the solubility being rapid increased with this temperature point called as catastrophe point. This feature is hold by ionic surfactants.

There are limited numbers of hydrophilic groups in the anionic type surfactant, but there are many types of hydrophobic groups. The raw materials of important hydrophilic group include carboxylic acid, sulfonic acid ester, sulfonic acid, phosphoric acid esters; the raw materials of hydrophobic group include animal and vegetable greases and their hydrolysis products, such as fatty acids, higher alcohols and the synthesized alcohols as petrochemical raw materials, alkanes benzene, α- olefins, etc., animal and vegetable oils include coconut oil, castor oil, cottonseed oil, palm oil, sperm whale oil, beef tallow and fish oil, etc. Furthermore, the rosin acid, naphthenic acid of the natural processed products have also been frequently used. Anionic surfactants also have excellent penetration, wetting, emulsification, dispersion, solubilization, foaming, decontamination, anti-static and smoothing properties.
Anionic surfactants have the largest yield in different categories of surfactants and can&#;t be mixed together with cationic surfactants for application due to precipitated in the aqueous solution to become ineffective. It can be used in combination with nonionic and amphoteric surfactants. It is commonly used as detergents, wetting agents, emulsifiers and dispersing agents. It is widely used in industry. In daily chemical industry, it is used in various kinds of detergent; in the field of cosmetics, it is used as the foaming agents of shampoos, bath, various kinds of creams, toothpaste, dispersing and emulsifying agents; in the field of food, it can be used as an emulsifier, defoamers, dispersants, preservatives, solubilizers, thickening agents and protein stabilizing agents and so on; it can also be used as feed emulsifier, dispersant, stabilizer; in the field of medicine, it can be used as emulsifiers, thickeners, preservatives, antioxidants and so on;

in the textile industry, it can be used as oiling agent, dyeing auxiliaries, bleaching agents, soft processing agent; in the field of pesticides, it can be used as spraying agents, emulsifying agents and dispersants; it can be used as asphalt emulsifier in highway and urban road construction such as tall oil sulfonate; in the field of civil engineering, it can be used as the water reducing agent of cement; in the development of oil field, it can be used as emulsifier, oil displacement agent, lubricant, sand consolidation agent, blocking agent, demulsifier, corrosion inhibitor, reducing agent, fluid loss agent and son on; it can be used as an emulsifier and fuel additive in the petroleum products; in the polymer industry, it can used as an emulsifier and antistatic agents during the emulsion and polymerization, antistatic agents; metal cleaning agent; mining flotation agent; water treatment agent; the brighteners, dispersants, pitting inhibitor in the plating solution and may be added to copper plating bath and nickel plating solution; it also has applications in other fields such as paint, ink, transportation, ship-breaking and other industries.

A Beginner's Guide to Working with Natural Surfactants

Trying to avoid SLS and other harsh surfactants in your cosmetics? There are many mild, natural surfactants available. Learn about the different types of natural surfactants, with a list of my favorites.

What is a surfactant?

There are many types of surfactants and they are used for many different purposes, but they all share one quality: they help increase the wetting properties of a liquid. Surfactants can be found almost everywhere. You can find them in everything from detergents and shampoos to toothpaste and even conditioners.

Surfactant definition:

(A surfactant,) also called surface-active agent, (is a ) substance such as a detergent that, when added to a liquid, reduces its surface tension, thereby increasing its spreading and wetting properties. (Encyclopaedia Britannica)

Some surfactants are emulsifiers, others are foaming agents (and some may actually do the opposite of those functions). Some act as detergents, while others act as insecticides or fungicides. Some help with solubilizing (small amounts of oils into water, for example) and others help increase viscosity.

How do surfactants work?

Surfactants affect the surface tension of liquids to increase wetting.

Why would you want to increase wetting?

Normally, when you spray water on a surface like a window, rather than spread evenly over the surface, the water will bead up. That&#;s because of the surface tension of the water. The molecules of the water come together in a stable configuration and are attracted to each other. When you are trying to clean that window, though, that beading isn&#;t helping you. You want the water to spread evenly over the surface to better clean it. You also want something that can grab onto the grease and dirt on whatever surface you are trying to clean.

Micelles in surfactants

Surfactants affect the surface tension that is making the water bead up rather than spread out. They have a water-loving head and an fat (oil) loving tail. They come together in structures called micelles.

The structure of a type of micelle.

I already explained a bit about how the micelles in surfactants work in my micellar water recipe, but for those who haven&#;t read that post, let me give you a quick, simplified explanation. The water-loving heads of the micelles bond with the water while the oil-loving tails on the inside of the micelles bond with the grease and grime. That pulls the grease and grime into the center of the micelles out of contact with the water, making them easier to rinse away.

You&#;ll also find that hot water helps clean better because the hot water helps melt the fats which makes it easier for them to be brought into the micelles.

Types of surfactants

There are four main types of surfactants, each behaving somewhat differently, and some with completely different functions. The detergent-like surfactants tend to be the anionic, non-ionic and amphoteric surfactants. Some cationic surfactants are used as emulsifiers and are great for hair conditioners. (I use BTMS, a cationic surfactant, in my hair conditioner recipe.)

These are classified based on the charge of the polar head of the surfactant which can have a positive charge (cationic), a negative charge (anionic), or no charge (non-inonic). Amphoteric surfactants have both a cationic and anionic part attached to the same molecule.

Anionic &#; Anionic surfactants are the most commonly used surfactants because they tend to provide the best cleaning power and the most foam. You&#;ve probably heard people talking about one of the most commonly used anionic surfactants, SLS (Sodium lauryl sulfate or Sodium Laureth Sulfate). It can be found in everything from shampoos and shower gels to even toothpaste. I&#;ve also shown you how to make soap (many types by now!), another anionic surfactant.
Anionic surfactants can be harsher on the skin, which is why they are often combined with other types of milder surfactants.
Nonionic &#; The second most commonly used surfactants are nonionic surfactants. They don&#;t ionize in water or aqueous solutions. Nonionic surfactants are gentler when cleaning. Because they don&#;t carry a charge, they are the most compatible with other types of surfactants. Recently, sugar-based nonionic surfactants have been developed to offer a safer, non-toxic alternative to some of the more harsh surfactants on the market up until now.
Cationic &#; Cationic surfactants don&#;t generally give foaming like the other types of surfactants. They are often used in hair care products (mainly conditioners and anti-static products because they don&#;t provide the foaming for use in shampoos) because their positive charge is attracted to the negative charge in hair. This makes it difficult to completely wash them from your hair, so some stays behind to help reduce friction between hairs which, in turn, reduces the amount of electrostatic charge in hair. This helps make hair more manageable and helps prevent damage.
Cationic surfactants aren&#;t usually compatible with anionic surfactants!
Amphoteric &#; Amphoteric surfactants can carry either a positive or negative charge depending on the pH of your product. Despite that, they are still compatible with all of the other types of surfactants. These tend to be very mild surfactants which is why they are usually combined with other surfactants. While amphoteric surfactants may not give a lot of foam on their own, they can help boost the foam of the other surfactants. Amphoteric surfactants are often combined with anionic surfactants to reduce their harshness and help stabilize their foam.

Natural surfactants list:

Natural surfactants can be derived from many types of plants. Common sources are coconut or palm, but they can also be derived from other types of fruits and vegetables.

There are many natural surfactants on the market today, and with increased consumer demand, I imagine that many more will be available in time. I have tried many of them, but today I&#;ll focus on some of my favorites. I like these surfactants because they are gentle, they tend to be easier to find, and they work well together. You can use these in everything from gentle shampoos to shower gels, facial cleanser, and baby washes.

Choosing your surfactants

Keep in mind that many of these surfactants are not palm free, so you&#;ll want to source them from places that allow for sustainable methods of obtaining their materials. I buy surfactants that have been certified sustainable by RSPO (Roundtable on Sustainable Palm Oil) standards.

Another thing to keep in mind is that these surfactants can differ from manufacturer to manufacturer. The names are polymeric and aren&#;t referring to an exact structure. Some places will use different plants as the origin of elaborating each surfactant, and the way each surfactant cleans, solubilizes, etc. can vary depending on where you buy it from. I&#;ll be describing these surfactants based on my suppliers, but you&#;ll want to check on the specifications of the surfactant you are buying if it&#;s important to you to know what plants have been used to derive them, the pH, the concentration, etc. Use this list as a general guideline!

Along those lines, while mine are listed as ECOCERT approved, that may also be dependent upon the manufacturer of each surfactant.

I&#;ll be updating this list and adding more surfactants as I use them and learn more about them. For now, though, this should give you a good starting point to understanding what we are going to be working with.

Coco Glucoside

Coco Glucoside is a non-ionic surfactant that is obtained from coconut oil and fruit sugars, but it can also be obtained from either potato or corn. It is a very gentle, foamy cleanser and is completely biodegradable. You can use it in products that you want to have an ECOCERT certification. It has an alkaline pH (around 12) which makes it self-preserving as is, but you will probably have to adjust the final pH of products using it to pull it into a range more suitable for your skin or hair (and you&#;ll need to add a preservative).

Decyl Glucoside

Decyl Glucoside is very similar to coco glucoside (non-ionic and ECOCERT compatible), but it has a shorter chain length. It creates less foam (its foam is less stable) than coco glucoside but it does add more viscosity to a product. It is derived from coconut oil and glucose and is completely biodegradable. It can be used in all sorts of shampoos, gels, baby products, etc.

Lauryl Glucoside

Lauryl Glucoside is very similar to the other 2 glucosides I&#;ve mentioned. It has a longer chain length and more viscosity. It takes longer to foam than the other two, but it also has the most stable foam. While it is also a mild cleanser, it isn&#;t as mild as the other 2 alkyl polyglucosides.

Comparing the alkyl polyglucosides. I bought the Lauryl Glucosde from a different supplier, so that may also be a factor in the huge difference in appearance. You&#;ll notice the Lauryl Glucoside I bought was relatively solid, and I had to dilute it quite a bit to be able to use it.

Disodium Laureth Sulfosuccinate

Disodium Laureth Sulfosuccinate is a gentle anionic surfactant that can be used in natural products (ECOCERT). It is a great alternative to SLS for a milder, more natural shampoo (or body wash, etc.). It has larger molecules than some of the other surfactants (like SLS) making it unable to penetrate and irritate the skin in the same way. It cleans and provides foam in products made for people with sensitive skin.

Notice

It has been pointed out to me that the EWG rating for Disodium Laureth Sulfosuccinate has been raised due to the concern that it may be contaminated with ethylene oxide or 1,4 dioxane during the production of this surfactant. It is still generally allowed in natural formulations because it is a mild surfactant. Use personal judgment on whether you feel comfortable using it or not.

Coco Betaine

Coco betaine is a coconut based amphoteric surfactant. It&#;s mild and can help boost foam and increase the viscosity of products made with it. It&#;s very mild and provides for gentle cleansing. It&#;s completely biodegradable and has a pH around 6-8. It is also ECOCERT compatible so it can be used in the elaboration of &#;natural&#; and &#;organic&#; type products.

Sodium Coco Sulfate

Sodium coco sulfate is an anionic surfactant that is ECOCERT and BDIH friendly. It has a pH of 10-11 and is derived from coconut oil. It is a water-soluble surfactant that is sold in solid form. It&#;s usually used in non-soap shampoo bars and/or bar cleaners (syndet bars).

Plantapon® SF

Plantapon SF is a mix of vegetable-based surfactants (coconut, corn, and palm based) that can be used in a variety of gentle cleansing products like shampoos, shower gels, and facial cleansers. It includes sodium cocoamphoacetate, lauryl glucoside, sodium cocoyl glutamate, sodium lauryl glucose carboxylate, and glycerin. It has a pH between 6.5 and 7.5.

Because this is a mix of surfactants, it can be a good choice for those who are just delving into working with surfactants. You can easily mix up formulations without needing to buy a lot of raw materials or doing a lot of work. (I&#;ll work on getting up some recipes that use this as soon as I can.)

Soap nuts and a soap nut solution.

Completely natural surfactants

While not as effective as the other more processed surfactants derived from natural sources, those looking for a completely natural alternative may be interested in studying some of these natural surfactants. These plant based cleansers all have natural saponins that are a type of non-ionic surfactant. They can be used alone or combined with the other surfactants for a more effective final product.

Soap Nuts (Soap Berries, Aritha)

The fruits taken from the sapindus trees/shrubs from the lychee family have saponins which are natural non-ionic surfactants. They are usually called either soap nuts or soap berries, and they clean without creating much foam.

You can either throw a cloth bag of them in with your laundry to naturally wash your clothes, or you can steep them in warm water to extract a liquid that can be used for cleaning. Make just enough for what you&#;ll need and you can freeze the rest.

Liquid Yucca Extract

Liquid yucca extract is a natural non-ionic surfactant that comes from the yucca plant, a desert plant that has natural saponins of its own. While you can add it to your homemade shampoos, yucca extract is also used in gardening to help get nutrients to the roots of other plants by washing away concentrated salts that build up.

Shikakai powder

Shikakai powder is another plant with natural saponins which are natural non-ionic surfactants. It is normally used in hair care as a very natural &#;shampoo.&#; It naturally has a low pH which makes it ideal for hair care. It&#;s said to be good for all hair types, especially those that are prone to breakage and damage. Like with the other natural surfactants, you can either combine it with other surfactants or use it on its own. To use it on its own, you make a paste by mixing the powder with warm water and running it through your wet hair once it the paste has cooled. You then leave it to act for 10-15 minutes before rinsing it out. It may slightly darken hair.

Soapwort

Soapwort is another plant that has been used for many years as a soap alternative. It can be used to clean the skin, wash your hair, or even as a laundry soap. It&#;s especially good for delicate fabrics. To use soapwort, you need to make an infusion of the soapwort in water, and then you can use the resulting liquid as a liquid soap alternative.

For more information, please visit Natural Surfactants List.