Instant water cleaning method better than commercial approach, scientists claim

The researchers at Cardiff University said the results could revolutionise water disinfection technologies and present an opportunity to provide clean water to communities that need it most.

The novel method works by using a catalyst made from gold and palladium that takes in hydrogen and oxygen to form hydrogen peroxide – a commonly used disinfectant currently produced on an industrial scale.

Industry makes over four million tonnes of hydrogen peroxide in factories each year, where they then transport it to the places where it’s used and stored. Stabilising chemicals are often added to the solutions during the production process to stop them degrading but these reduce its effectiveness as a disinfectant.

Another common approach to disinfecting water is the addition of chlorine. But experts have found that chlorine can react with naturally occurring compounds in water to form compounds that, in high doses, can be toxic to humans.

According to the research team, the ability to produce hydrogen peroxide at the point of use would overcome both efficacy and safety issues currently associated with commercial methods.

Graham Hutchings, a professor of chemistry at the Cardiff Catalysis Institute, said: “The significantly enhanced bactericidal and virucidal activities achieved when reacting hydrogen and oxygen using our catalyst, rather than using commercial hydrogen peroxide or chlorination, shows the potential for revolutionising water disinfection technologies around the world.”

In their study, the team tested the disinfection efficacy of commercially available hydrogen peroxide and chlorine compared to their new catalytic method. They tested each for its ability to kill Escherichia coli in identical conditions, followed by subsequent analysis to determine the processes by which it killed the bacteria using each method.

They found that as the catalyst brought the hydrogen and oxygen together to form hydrogen peroxide, it simultaneously produced several highly reactive compounds, known as reactive oxygen species (ROS). The team showed these handled the antibacterial and antiviral effects, and not the hydrogen peroxide itself.

The catalyst-based method was 10,000,000 times more potent at killing the bacteria than an equivalent amount of the industrial hydrogen peroxide, and over 100,000,000 times more effective than chlorination, under equivalent conditions. The method was also more effective at killing the bacteria and viruses in a shorter space of time compared to the other two compounds.

Experts estimate that around 785 million people lack access to water and 2.7 billion experience water scarcity at least one month a year. Inadequate sanitation – a problem for around 2.4 billion people around the world – can also lead to deadly diarrhoeal diseases, including cholera and typhoid fever, and other water-borne illnesses.

“We now have proven one-step process where; besides the catalyst, inputs of contaminated water and electricity are the only requirements to attain disinfection,” Hutchings explained. “Crucially, this process presents the opportunity to disinfect water over timescales in which conventional methods are ineffective, whilst also preventing the formation of hazardous compounds and biofilms, which can help bacteria and viruses to thrive.”