Nanofiltration membranes based on polyvinylidene fluoride nanofibrous scaffolds and crosslinked polyethyleneimine networks

In this article, we describe the synthesis of new and ion-selective nanofiltration (NF) membranes using polyvinylidene fluoride (PVDF) nanofibers and hyperbranched polyethylenimine (PEI) as building blocks. These new nanofibrous composite (NFC) membranes consist of crosslinked hyperbranched PEI networks supported by PVDF nanofibrous scaffolds that are electrospun onto commercial PVDF microfiltration (MF) membranes. A major objective of our study was to fabricate positively charged NF membranes that can be operated at low pressure with high water flux and improved rejection for monovalent cations. To achieve this, we investigated the effects of crosslinker chemistry on membrane properties (morphology, composition, hydrophobicity, and zeta potential) and membrane performance (salt rejection and permeate flux) in aqueous solutions (2,000 mg/L) of four salts (NaCl, MgCl2, Na2SO4, and MgSO4) at pH 4, 6, and 8. We found that an NFC–PVDF membrane with a network of PEI macromolecules crosslinked with trimesoyl chloride has a high water flux (*30 L m h) and high rejections for MgCl2 (*88 %) and NaCl (*65 %) at pH 6 using a pressure of 7 bar. The overall results of our study suggest that PVDF nanofibers and hyperbranched PEI are promising building blocks for the fabrication of high performance NF membranes for water purification. Special Issue Editors: Mamadou Diallo, Neil Fromer, Myung S. Jhon This article is part of the Topical Collection on Nanotechnology for Sustainable Development S.-J. Park R. K. Cheedrala M. S. Diallo (&) W. A. Goddard III Graduate School of Energy, Environment, Water and Sustainability (EEWS), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea e-mail: [email protected]; [email protected] Present Address: S.-J. Park Department of Bioresources and Rural Systems Engineering, Hankyong National University, Anseong, Greonggi-do 456-749, Republic of Korea M. S. Diallo Environmental Science and Engineering, Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA C. Kim I. S. Kim Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea W. A. Goddard III Materials and Process Simulation Center, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA 123 J Nanopart Res (2012) 14:884 DOI 10.1007/s11051-012-0884-7