Latest Research Highlights

Eco-friendly nanotechnology-based anti-fouling technologies for maritime industries

18 Nov, 2019 | Return|

Marine biofouling is the unwanted growth and accumulation of organisms on submerged man-made surfaces, such as vessel hulls, buoys, nets, pipers, prier pilings and membranes of desalination plants. Biofouling organisms, ranging from the size of tenths of a millimeter to centimeters, cause numerous technical and economic problems to maritime industries. Biofouling on ships’ hulls reduces the speed of vessels by increasing the ship’s drag, thus it has to burn much more fuel to move quickly. Biofouling can clog water intake pipes and heat exchanges, as well as reduce buoyancy and damage materials and equipment working in the sea. Biofouling of reverse osmosis (RO) membranes of desalination plants seriously affects their operation in terms of reduction of the filtration process and the quality and cost of the produced water. In order to prevent biofouling, engineers employ different techniques which are based on application of toxic substances, such as chlorine, copper, and organic biocides that kill marine organisms. All of these are harmful to humans and destroy and pollute the marine environment. Nanotechnology is concerned with the manipulation of materials at nanometer (one billionth of a meter) scale. At this scale, materials gain new physical and chemical properties that can be used in different industrial applications ranging from new packaging materials to superfast electronic microchips. Nanotechnology opens a new way to prevent biofouling. Nano-coatings are less toxic than traditional antifouling coatings and provide protection via chemical and physical surface modifications at nano-scale. In this regard, we have led a research team to investigate the antifouling properties of a photocatalytic nanocoating. When this nano-coating is exposed to sunlight, the zinc oxide (ZnO) atoms react with water to form reactive oxygen species (ROS) such as oxygen ions and peroxides. ROS quickly break down any attached organic matter and fouling organisms on the surface of the coating. In laboratory experiments, we found that, with sunlight irradiation, ZnO nano-coatings on glass slides could prevent bacterial fouling and completely inhibit the settlement of bryozoans. In another study, it was demonstrated that ZnO nano-coatings have anti-algal activity against planktonic microalgae causing harmful algal blooms (HABs) in Oman waters. In the laboratory experiments, nano-coatings eliminated 98% of microalgae at densities higher than those during HABs. In comparison with chlorination treatment, no re-growth of microalgae was observed even after 2 weeks of incubation. In an open door experiment under natural sunlight, ZnO nano-coatings significantly reduced densities of bacteria and diatoms on the coated substrata. Antifouling activity of ZnO nano-coatings has been proven in a 1 month field experiment in Al Mouj marina. These findings have been published in high impact factor peer review journals. While these nano-coatings are a significant step forward in the production of an eco-friendly antifouling coating, potential risks to human health and environment still need to be carefully studied.