Researchers from Cardiff University claim that a water disinfectant made right away using hydrogen and air is more highly effective against bacteria and viruses than conventional commercial methods.
The researchers note that their results could completely transform present-day water disinfection technologies. It also offers an exceptional opportunity to provide clean water to communities in need. The results have been published in the journal Nature Catalysis.
The newly devised method uses a catalyst made from palladium and gold that absorbs oxygen and hydrogen to form hydrogen peroxide. Hydrogen peroxide is widely used as a disinfectant and is currently produced on an industrial scale.
Factories produce more than four million tonnes of hydrogen peroxide every year, which is then transported to the locations of use and stored. To prevent degradation during storage and transportation, stabilizing chemicals are often added to the solution during production. However, these chemicals affect its effectiveness as a disinfectant.
Adding chlorine is another usual method for disinfecting water. But chlorine reacts with naturally occurring compounds in water to form compounds that might be toxic to humans, in higher doses.
Hydrogen peroxide produced instantaneously at the operating site overcomes both safety and efficacy issues — both associated with commercial techniques used at present. The researchers tested the disinfection potential of the newly developed method against commercially available hydrogen peroxide and chlorine.
The ability of the disinfectant to act against Escherichia coli under the same conditions was tested, subsequently followed by an analysis to identify the processes by which the bacteria were killed using each method.
They demonstrated that the catalyst used for synthesizing hydrogen peroxide from hydrogen and oxygen led to the production of many highly reactive compounds, called reactive oxygen species (ROS). The researchers showed that the ROS was responsible for the antiviral and antibacterial effect, and not hydrogen peroxide itself.
The catalyst-based method was found to be 10,000,000 times more potent at destroying the bacteria than an equivalent amount of the industrial hydrogen peroxide. It was more than 100,000,000 times more effective compared to chlorination, under the same conditions.
The catalyst-based method was effective at killing viruses and bacteria in a brief time than the other two compounds. According to estimates, about 785 million people lack access to water and 2.7 billion people experience water scarcity at least one month a year.
Around 2.4 billion people worldwide face inadequate sanitation, leading to deadly diarrheal diseases, such as typhoid fever, cholera, and other water-borne illnesses.
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 revolutionizing water disinfection technologies around the world.
Graham Hutchings, Study Co-Author and Regius Professor of Chemistry, Cardiff Catalysis Institute
“We now have proven a one-step process where, besides the catalyst, inputs of contaminated water and electricity are the only requirements to attain disinfection,” added Prof. Hutchings.
“Crucially, this process presents the opportunity to rapidly 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.”Graham Hutchings, Study Co-Author and Regius Professor of Chemistry, Cardiff Catalysis Institute.
Richards, T., et al. (2021) A residue-free approach to water disinfection using catalytic in situ generation of reactive oxygen species. Nature Catalysis. doi.org/10.1038/s41929-021-00642-w.