Researchers develop nano-coatings for water treatment

Muscat: The research team headed by Dr Sergey Dobretsov, the Director of Centre of Excellence in Marine Biotechnology, Sultan Qaboos University (SQU) together with his colleagues from University of Western Cape (UWC), South Africa are developing photo-catalytic coatings on polymer supports for effective filtration of organic contaminants from water and antifouling applications.
SQU and National Research Foundation, South Africa fund this investigation. The main objective of the project is to use the complementary skills, background knowledge of the South African and Oman teams, train students and young researchers from UWC and SQU in the field of nanotechnology and biotechnology.
Nano-technology referred to the manipulation of materials at nanometer scale (or 10000 times less than width of a human hair). At this scale, materials gain new physical and chemical properties that can be used in different industrial applications. Nano-technology opens a new way to prevent bio-fouling. Nano-coatings are less toxic than traditional antifouling coatings and provide protection via chemical and physical surface modifications at nano-scale.
Dr Dobretsov together with Dr Mohammed Al-Abri, the Director of the Center of Nanotechnology, SQU and Prof. Leslie Petrik, UWC are investigating antifouling properties of doped transition metal oxides, such as titanium oxide (TiO) and zinc oxide (ZnO). When such nano-materials are exposed to sunlight, an electron in the atom moves to a higher energy level. This process creates negatively charged electrons and positively charged holes, which can react with water molecules to form reactive oxygen species (ROS), such as oxygen ions and peroxides. ROS are quickly break down any attached organic matter and fouling organisms and do not accumulate in the environment.
In laboratory experiments, South African and Omani teams were able to demonstrate that upon solar irradiation, photocatalytic nano-coatings could prevent bacterial growth and bacterial fouling. About of 90 per cent of tested bacteria were eliminated and no bacterial re-growth was observed. Additionally, such nano-coatings can degrade and remove water contaminants, such as dyes. This effect was observed under artificial light, as well as sunlight in an outdoor experiment. These nano-coatings can work for water purification and disinfection. Moreover, nano-coatings keep membranes clean from bio-fouling. While these photocatalytic nano-coatings are a significant step towards the production of an eco-friendly antifouling coating, potential risks to human health and environment need to be carefully studied. In the future, both teams would like optimise production of these nano-coatings and test them in relevant industrial applications.