A group of Iranian researchers from Babol University of Technology succeeded in the production of polysulfonic nanofiltration membranes with desirable performance and high stability in non-aqueous media. The membranes can be used in foodstuff industries, chemical industries, wood and paper industries, medical industries, oil and petrochemical industries, and so forth. The synthesis of solvent resistant nanofiltration membranes at semi-industrial scale by using nanotechnology to purify biodiesel not only fulfils the environmental requirements, but also plays an important role in reducing the price of biodiesel. Dr. Majid Peyravi explained the objectives of the research, and said, “The aim of the research was to strengthen the thin layer composite nanofiltration membrane by using nonlinear compounds (sulfonic copolymers) as the additive to modify the membrane components. Moreover, the presence of functional groups such as ether, sulfide, and sulfoxide in the structure of the sulfonic copolymer improves the reactivity and chemical and thermal resistance of the membrane components.” According to Dr. Peyravi, commercial nanofiltration membranes are usually used to separate the dissolving part from the aqueous phase. This fact limits the application of the membranes only to water and wastewater purification. Taking into consideration the fact that in many cases, the dissolving part must be separated from a non-aqueous solution, ordinary nanofiltration membranes cannot be used due to their low chemical and thermal stability in non-aqueous solvents. Solvent resistant nanofiltration membranes are a new generation of nanofiltration membranes that in addition to having high chemical and thermal stability, they possess all other advantages of nanofiltration membranes in the purification and separation processes. Results of the research have been published in details on 15 December 2013 in Journal of Membrane Science, vol. 423-424, pp. 225-237.