by Prof. Mohamed Khayet, Faculty of Physics, University Complutense of Madrid, Spain.
Membrane Distillation (MD) is a non-isothermal separation technology used for the treatment of high salinity waters and Reverse Osmosis (RO) brines up to saturation. It is capable to produce not only distilled water but also ultra-pure water. Its drawback is the no availability of membranes designed specifically for MD. Among other characteristics, such as a high hydrophobicity and porosity, an MD membrane should exhibit a high liquid entry pressure into its pores and low heat transfer by conduction.
Different surface modification techniques such as coating, radiation graft polymerization and plasma polymerization are used to modify the structural characteristics and chemical properties of different types of membranes. In general, these techniques involve more steps during membrane fabrication line increasing their cost and changing their surface physical structure (e.g. change of the pore shape reducing its size or even closing it).
We have developed a simple procedure to prepare composite double layered hydrophobic/hydrophilic membranes for MD without any post-modification step using fluorinated polyurethane additive (FPA). Because of its low Gibbs free energy compared to the host hydrophilic polymer, FPA migrate to the air/membrane interface during its formation changing its surface chemistry. Various types of FPA modified membranes have been prepared using different hydrophilic host polymers and FPAs synthesized with different formulations. Not only we could prepare flat-sheet membranes with very high MD desalination performance, but also robust MD hollow fiber membranes. Recently, we could modify the surface of polymeric nanofibers by FPA and prepare electrospun nanotextured membranes with very high MD salt rejection factors and water production rate.
Prof. Mohamed Khayet: Director of the University Complutense of Madrid (UCM) Research Group “Membranes and Renewable Energy” affiliated to Campus Moncloa of International Excellence (Madrid, Spain); Full Professor at the Faculty of Physics (UCM) and Associated Researcher in IMDEA Water (Madrid Institute of Advanced Studies on Water, Spain). He got his Ph.D. in Physics from the UCM. He realized various research stays in different international institutions (Industrial Membrane Research Institute in Ottawa, Canada; Institute of Nuclear Chemistry and Technology in Warsaw, Poland; Centre for Clean Water Technologies at the University of Nottingham in UK, Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University in Singapore, Yale University, Berkeley University, etc.). His main research field is membrane science and nanotechnology. He has coordinated various national and international projects funded by different institutions (EU, Middle East Desalination Research Center, Spanish Ministries; Companies such as Abengoa Water, etc.) and published over 170 papers since 2000 in international journals with 11384 total citations and an H-index of 61 (Google Scholar). He filed 6 International Patents and published 3 books on membrane science and technology. Among other awards, he received the Prince Sultan Bin Abdulaziz International Prize for Water (PSIPW) in 2012 for his novel and creative works on membrane distillation technology that he has studied and promoted in all its theoretical and experimental aspects (from membrane synthesis to implementation). He is co-editor of the Journal “Desalination” and member of the Editorial Board of various other journals: “Applied Membrane Science & Technology”, “Membrane Water Treatment (MWT)”, “Membranes”, “Polymers”, “Applied Sciences”, “Journal of Materials Science and Nanotechnology”, “Journal of Membrane Science and Research”, “Scholarena Journal of Nanoscience and Nanotechnology”, “Nano Research & Applications”, etc.
His research experience and expertise include among others membrane engineering (flat sheet, hollow fiber, nanotextured and 2D membranes) for different membrane separation processes (Membrane distillation, ultra- & nano-filtration, forward osmosis, reverse osmosis, pervaporation, etc.), nanocomposites, water-energy nexus, development of theoretical models, optimization (RSM, ANN), fouling, desalination, solar thermal and photovoltaic systems, thermal conductivity and diffusivity of phase change materials (PCMs) & nanofluids.