Membrane displaying a dual thin-film titanium-zirconium as selective layers for water treatment

Abstract

A single dual thin-film titanium-zirconium as selective layers membrane for divalent and monovalent ions removal was fabricated. Both dioxide of titanium (TiO2) and dioxide of zirconium (ZrO2) have been co-deposited on an ultrafiltration polyacrylonitrile membrane using information given by scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS). The important insights provided by SEM associated with EDS on the arrangement and potential functions of nanoparticles (NPs) due to their unambiguous chemical signal were used for characterization and modification of membrane surface at an atomic scale. Thus, a novel thin-film composite-nanofiltration membrane (TFC-NFM) has been performed for the first time. The new-born organic–inorganic membrane NF-TiZr exhibited excellent performance rejection towards monovalent ions and its rejection rate for multivalent ions reached 95%. The order of salts rejection was CaCl2 > MgSO4 ~ MgCl2 > NaCl > Na2SO4. The permeate flux of the NF-TiZr membrane is as high as 58 L m–2 h–1. 180 h-continuous exploitation of NF-TiZr showed a slight variation of permeate flux less than 1.2% and the salt rejection remained high than 92.5% at the end of the operation. To our best knowledge, it is the first time SEM was combined with EDS to help for optimal co-deposition of nanoparticles on the membrane surface. This study may provide useful insights to design next-generation NFMs.