Removing charged species from aqueous media is of interest in diverse applications including desalting of saline water. Capacitive deionization (CDI) devices governed by the principles of a supercapacitor use two conductive electrodes which are preferably nanostructured to provide large surface area for adsorption of ions. Practical capacitive deionization systems operate at very low voltages, lower than the dissociation potential of water and unlike Reverse Osmosis, which is popularly used for desalination, capacitive deionization has been shown to be energetically favorable for desalting brackish water.

While it is generally accepted that the specific surface area of the electrode is the primary factor governing the salt removal capacity of the electrode, researchers at Sultan Qaboos University have broken the myth and demonstrated that in practical applications, it is the specific capacitance of the electrode and not the surface area which regulates electrode performance in a capacitive device. Additionally the work highlights the effect of asymmetry in terms of specific capacitance between the two electrodes and proposes a simple electrical model and its dependencies to qualitatively assess the desalting performance. The results show that the electrode with smaller capacitance is the limiting factor, indicating that anode-cathode capacitance should be matched for practical capacitive deionization units to achieve maximum desalting capacities.

The demand for innovation in water treatment, environmental remediation and energy technologies has progressively increased over the years. Nanotechnology has emerged as a viable solution poised to revolutionise the environment sectors especially in the fields of water, energy and pollution control. SQU with the support from the Research Council of Oman (TRC) and the US Office of Naval Research Global (ONRG) has organised the conference entitled “Nanotechnology for Water Treatment and Solar Energy Applications” in  Muscat last month. Three major themes were identified including nanotechnology for water treatment, desalination and biofouling; Solar energy and environmental applications; Nanotechnology for environmental science and engineering.

The aim of the conference was to serve as a forum for distinguished researchers, increase knowledge dissemination and capacity building, as well as set the stage for future collaborations between institutes, centres and industries worldwide. The conference featured 104 delegates from 13 different countries and 31 oral and poster presentations have been given. The proceedings from the conference in terms of peer-reviewed articles will be published in the Elsevier journal “Groundwater for Sustainable Development”. Professor Amer Ali al Rawas Deputy Vice-Chancellor, SQU, and Dr  Ammar al Obeidani, TRC opened the conference. Four keynote addresses from Professor Jérôme Perrin, Scientific Director of Renault company, France, Professor Kishore Paknikar, Director of Agharkar Research Institute, India, Professor Joydeep Dutta, Chair in Functional Materials, KTH Royal Institute of Technology, Sweden (formal Chair in Nanotechnology, SQU), and Professor Yves Blache, University of Toulon, France were given.

“Recognising the pioneering role of Sultan Qaboos University (SQU) in the Sultanate’s higher education sector as the most prominent institution for teaching, research and community service, the first Chair of Oman’s TRC was granted to SQU four years ago in order to meet the increasingly changing needs of development in the Sultanate and leverage the existing and future capacity in Nanotechnology, with a special focus on Water Desalination. This boosted up multidisciplinary nano-technological investigations in the country and put Oman on the map together with other developing countries doing research in the field of nanotechnology”, Professor Joydeep Dutta said. In his talk he highlighted several important achievements of the chair of nanotechnology programme, such as establishment of the fully equipment nanotechnology laboratory and the start of multidisciplinary research in the fields of desalination and water treatment that resulted in the creation of a prototype for capacitive deionisation of brackish waters.

“Biofouling is refereed to undesirable accumulation and growth of marine organisms on the surfaces of man-made installations. Biofouling cost billions of dollars for marine industries, such as ship and boat owners, desalination plants and aquaculture. Thus, it is important to prevent this adverse process. Modern ways of prevention from biofouling include the usage of toxic compounds, such as copper, chlorine and organic biocides that kill corals and fishes and accumulate in the environment. Due to the high detrimental impact of antifouling compounds there is a strong need to develop successful, non-toxic green antifouling solutions”, said Professor Yves Blache.

Professor Jérôme Perrin reminded the audience about necessity of reduction of CO2 emissions in order to stop global warming. “Electric eco-friendly cars can provide new green solutions to cut greenhouse emissions. Innovations in solar panels, batteries, electricity networks in order to reduce cost and increase their efficiency are required. These can be achieved through nanotechnology“, he added.

All speakers at the conference emphasised that we are living in “the world on the edge” and there is a strong demand in clean water, clean environment and renewable energy. These can be done only through combination of existing conventional techniques with nanotechnology enabling emerging techniques to address major challenges. Oman and all Gulf region countries could benefit from high amount of solar energy every day, which should be used in many novel applications.