Preparation of thin film composite nano-filtration membranes for brackish water softening based on the reaction between functionalized UF membranes and polyethyleneimine

Publication date: Available online 23 June 2019Source: Journal of Membrane ScienceAuthor(s): Farideh Zarei, Rozita M. Moattari, Saeid Rajabzadeh, Maryam Bagheri, Abolfazl Taghizadeh, Toraj Mohammadi, Hideto MatsuyamaAbstractA new method was developed to prepare a low-pressure nano-filtration membrane based on the membrane surface reaction (functionalized UF blend membrane) with polyethyleneimine (PEI) to fabricate thin film composite (TFC) membranes for water softening applications. The TFC selective layer was prepared by a reaction between the carboxyl functional groups of a carboxylated polyether sulfone (C-PES)/PES UF blend membrane and PEI. Hyper-branched PEI (HPEI) and PEI were used as poly-cations for fabricating the TFC NF membrane. Glutaraldehyde was used to cross-link the PEI on the membrane surface. The effects of the poly-cation concentration, crosslinker concentration, reaction time, reaction temperature, pH, and NaCl concentration as the supporting polyelectrolyte on the water permeability (WP) and rejection were evaluated. The addition of C-PES lead to the formation of finger-like structures and increased the water flux. While the effect of the polycation solution pH value was found to be the dominant parameter, optimization of the reaction time and concentration was necessary to obtain a membrane with acceptable water filtration capability. An NF membrane with WP as high as 10.1 LMH/bar and MgCl2 (1000 ppm) rejection of 90% was obtained.
Source: Journal of Membrane Science - Category: Materials Science Source Type: research