Various international databases place prof. Seeram Ramakrishna among the top 25 authors and most cited materials scientists worldwide.
This is what he has to say about the latest nanofiber contribution in liquid filtration:
Nafigate: Can you, explain why are nanofibers so revolutionary in liquid filtration?
S. Ramakrishna: In the recent past the liquid filtration industry has not seen major innovations in filter media. Industry is hungry for better performing membranes as the liquid filtration purposes widen and grow.
Electrospun nanofiber filter media is a recent entry into the liquid filtration industry. Nanofibers yield enormous surface area, a great advantage for the filter media used in filtration applications. The surface area to weight ratio increases tremendously when the size of the material is reduced to nano-meter scale. Nanofibers also allow for tuning of pore size, pore distribution and porosity, which promise for high separation efficiency for filtration and purifications applications.
Nafigate: What is the current development status, are there any products on the market?
S. Ramakrishna: Comparing with conventional filter media, the electrospun nanofiber filter media offer several benefits including reduced material requirements, reduced energy consumption, and lower operation cost. The flux rate of nanofiber filter media for microfiltration has already been shown to be greater than the value for the classical media by companies. Advancements in nanofiber production technologies offer for the fabrication of industrial filter media using nanofibers with reduced pressure loss. Frontier companies such as Ahlstorm, Donaldson, eSpin, Stonybrook purification, HVision Platform Technology, Milliken & Company etc. understood to have embraced the nanofiber filter media. These nanofiber products promise for lower pressure drop and longer life at lower energy costs and high filtration efficiency.
Nafigate: What are your achievements in this field?
S. Ramakrishna: We developed electrospun nanofiber filter media suitable for microfiltration, ultrafiltration and Nanofiltration applications, which exhibit superior features, including high energy efficiency, structural durability and operational stability. Our benchmarks study with commercially available membranes has shown that our novel membrane provides higher flux, greater energy savings and higher pressure tolerance.
Nafigate: What are the biggest hurdles in development and how can be those hurdles passed?
S. Ramakrishna: By definition the nanofibers are small in dimension and hence pose challenges in producing filter media with adequate structural stability and durability. Operational demands in microfiltration, ultrafiltration, nanofiltration and membrane bioreactor applications are severe. Careful selection of materials and secondary chemical processes (interfacial polymerization, surface grafting, phase inversion, etc) adopted help to mitigate the operational challenges. Typical electrospun filter media will have pores larger than 100 nanometers. For ultra-filtration and nanofiltration purposes, the pore size needs to be smaller than 100 nanometers. This can be achieved by concepts such as calendaring, thin film composite approach. The quality of electrospun nanofiber layer in terms of uniform porosity and fiber diameter distribution, is the key to ensure production of thin and uniform selective barrier layer on top of the nanofibrous scaffold.
Other big challenge is membrane fouling. The contaminants that adhere to the membranes during filtration over the period of time lead to the formation of fouling, thus affect the performance and life time of the membranes. Approaches such as using an antifouling/super hydrophilic coating on the membranes have already shown promises to extend the life of the membranes.
Nafigate:When can we expect nanofibers based nanofiltration membrane product on the market?
S. Ramakrishna: Nanofibers in water filtration applications no longer require further proof of concept because the nanofibers based microfiltration membranes have already been in the market, and nanofibers in lab-scale ultra filtration and nanofiltration membranes have been successfully demonstrated and achieved higher efficiency, which are also available in scientific reports and literatures. Nanofibers based filter media is a rising star in the modern filtration domain and reaching remarkably rapid progress. Research on nanofibers for nanofiltration, membrane bioreactors, and reverse osmosis applications are gearing up, and this should bring up new way of making membranes that can hopefully reach market in the near future.
Nafigate: Is there any message you would like to pass to Nafigate readers?
S. Ramakrishna: Global issues such as the need for clean water continuously throw open challenges to industries, thus inviting R&D experts to solve specific scientific and technological problems. I am happy to note that the ‘NAFIGATE Portal’ is aimed to facilitate the establishment of partnerships between industries and R&D, academic experts for common goals, which also lead to enterprise competitiveness and new business opportunities. I wish NAFIGATE visitors, readers and members for the continued success in productive partnership and successful entrepreneurship.
Professor Seeram Ramakrishna, FREng, FNAE is the Director of Centre for Nanofibers & Nanotechnology at the National University of Singapore. Various international databases place him among the top 25 authors and most cited materials scientists worldwide. He is a recognized global leader for advancing the field of nanofibers in both academia and industry. He authored about five hundred peer reviewed papers, five books, and thirty patents. Over the past fifteen years he served in several senior academic leadership positions at NUS and as a board member of national organizations. He received PhD from the University of Cambridge, and general management training from the Harvard University. He is an elected international fellow of major professional societies in Singapore, ASEAN, India, UK and USA.
Fonte: Nafigate
