Can we wash our clothes without using detergents?
With or without detergents? This is the goal pursued by a team of scientists from Sweden’s Malmö University. Researchers are trying to understand what happens chemically and physically when they use treated water to remove impurities. There is still a lot of work to do. However, in the long run, this research, published in Science Direct, will allow us to solve a major environmental problem related to the use of detergents.
The destructive effect of detergents on the environment
Detergents are products used to clean clothes. They contain soap and surfactants. These surfactants allow, among other things, to break the bonds between the fabric and the dirt to remove it. Unfortunately, these chemicals are not environmentally friendly. Indeed, they are produced and widely used. In Europe alone, more than 3 million tons of detergents were produced in 2020.
Whether these detergents are used in liquid, powder or other form, they affect soil and water. Common detergents featured in television commercials are petroleum-derived compounds. Once in the environment, they do not break down as they should. Some of them are not even biodegradable. It then accumulates in soils and waterways.
These detergents contain chemicals such as sulfates, phosphates, bleaches, chemical fragrances, and phenols. After being evacuated from the washing machine, they end their lives in sewers, then in treatment plants and rivers to reach the sea and oceans.
You should know that more than 60% of surfactants in detergents end their life in the water environment. This causes major environmental pollution problems.
These substances are not without effect on health. Indeed, after the cleaning procedure, 2.5% of the detergent remains in the fibers of the clothes. It can cause skin irritation, inflammation and allergic reactions in some people.
Also read: What is the secret of clean laundry?
The issue of attractive forces and repulsive forces
To reduce the effect of detergents, scientists all over the world have started research. Their goal is to find greener detergents based on natural sources. For example, effective surfactants are now available. They are completely biodegradable and less toxic to the environment.
Researchers at Sweden’s Malmö University have started a new approach. The latter consists in the complete elimination of detergents and the use of only water. That’s a tall order. Indeed, it is important that the washing quality remains the same as that obtained by using detergents.
In many cases, it is possible to remove water-soluble or hydrophilic stains using only water. On the other hand, hydrophobic soils are insoluble and their removal with water is a problem. Surfactants in conventional detergents allow you to remove the hydrophobic properties of certain stains and therefore dissolve them to remove them.
It is impossible to dissolve hydrophobic impurities in water. However, the researchers realized that it is quite possible to disperse them temporarily, at least in suspension. There are many different forces in such a mix. We see electrostatic interactions and van der Waals forces. They are important to maintain the stability of the suspension. This implies a balance between the attractive and repulsive forces acting on the particles. The particles must be dispersed properly. For this, repulsive forces (electrostatic interactions) must prevail over attractive forces (Van der Waals forces).
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Only ultra-pure water for cleaning clothes
Researchers have performed various purification experiments with different types of water. They used tap water, water with added SDS (sodium dodecyl sulfate), detergent and strong ionic surfactant, and two different grades of purified water (distilled and ultrapure). They used a real-time technique called QCM-D. This allows us to analyze surface phenomena such as adsorption and desorption, or even the bonds formed between a liquid and a specific surface.
Scientists used petroleum jelly to simulate dirt in their experiments. They obtained 90% extraction of petroleum gel on a glass slide for both purified waters at 25°C. The researchers then experimented with several wash cycles and different temperatures. They were able to remove 100% of the oil at 40°C in two washing cycles with ultrapure water.
Ultrapure water is water extracted by filtration. It contains only H+ ions and OH- ions. It is also free from salts, minerals, metals and other impurities.
Scientists will now continue their research. They will use oil on plastic, which sticks tighter than Vaseline on glass.
Also read: Why making your own cosmetics is a bad idea?