Is it time to ditch the detergent?

Could washing clothes without detergent become a thing of the past?

Scientists at a university in Sweden say that an early-stage investigation into whether laundry can be cleaned with purified water - and no detergent - looks promising.

Water pollution caused by detergents is a big concern globally, with hazardous chemicals present in detergents entering water bodies and food chains. When these substances bio-accumulate, they can pose serious environmental and health risks.

Professor Vitaly Kocherbitov from the department of biomedical science at Malmö University says, “In the long run, our research can solve environmental problems with water pollution caused by detergents. To succeed in this, we need to better understand the intermolecular forces that act in purified water.”

The scientists hypothesise that in purified water – water that has been filtered and deionised so that impurities and especially ions are removed – repulsive forces between charged objects become stronger. As a result, dirt particles detach more easily from surfaces and become finely dispersed in the water.

"Our research can solve environmental problems with water pollution caused by detergents."

Professor Vitaly Kocherbitov, Malmö University

“Our goal is to develop a scientific model that explains what happens both chemically and physically when dirt is removed in purified water," says Andriani Tsompou, a PhD candidate working on the project. "When it comes to washing with detergents we already know what happens, but this is an unexplored area.

“When you have salt in the system, the dirt you want to remove will clump together more and make it harder for the water to remove the particles from the material.”

According to earlier results, Tsompou and her colleagues used water with different properties - tap water, water with added salt, and two grades of purified water. A specialised technique analysed surface interaction of the different waters on Vaseline applied to a glass slide. It showed a 90% purification of Vaseline for both grades of purified water at 25°C temperature.

In later trials, the researchers have experimented with several washing cycles and with different temperatures and achieved 100% purification in purified water at 40°C in two washing cycles. In these trials, the most favourable conditions have been assumed by choosing surfaces and dirts that form weak bonds.

“We have used water-friendly surfaces such as glass and silicate which have a negative charges and then olive oil or Vaseline, which also can get negative charges, so that they release each other easily," explains Tsompou.

The idea is to gradually increase the bond strength and change the materials so that they finally approach real conditions.

“Because these are such complicated processes, we have to build up knowledge from less complicated areas. The next step will be oil on plastic which attach more strongly to each other. The end-goal is of course to test on real fabric,” says Tsompou.

The study published in the Journal of Colloid & Interface Science.