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In this study, a simple and facile approach was proposed to synthesize silver nanoparticles (AgNPs) loaded cation-exchange membranes (CEMs). A wide analytical study involving scanning electronic microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was accomplished to corroborate that the in situ generated AgNPs were uniformly dispersed in the polymer matrix. In addition, as a result of the proposed synthesis strategy, the cross-linking structure inside the membrane was formed. The proper particle size and dispersibility of the AgNPs improved the mechanical properties of the membranes. Besides, the optimal AgNP-loaded CEM exhibited excellent bacterial killing activities against Gram-negative bacteria and showed a controlled improvement in the electrochemical performance of the prepared membranes. These effects were caused by the obtained distribution of AgNPs near ion-exchange groups that increased the aggregation of water molecules around them, improving the efficiency of ion transport due the formation of array broad ion-transport channels. The optimized CEM [sulfonated polysulfone (60SPSF)-C3#-Ag-2] exhibited an enhanced NaCl removal ratio of 67.5% with a high current efficiency (96.9%) and a low energy consumption (5.84 kWh kg–1). The distance of the inhibition zone from the boundary of the membrane of SPSF-C3#-Ag-2 reached 4.8 mm. These results led us to suggest that the proposed synthesis strategy may have potential applications in the field of antibacterial and desalting ion-exchange membranes.

In digital printing, a high salt content in dye solutions is detrimental, which calls for effective strategy for dye/salt fractionation. In this study, a loose nanofiltration (NF) membrane Sepro 2A was employed to desalinate diverse dye species (2 reactive dyes and 4 cationic dyes). This membrane, with a molecular weight cutoff of 490 Da, showed consistently high rejections to all the reactive and cationic dyes (>97.7%). Operational conditions such as dye concentrations and applied pressures have limited effects on the rejection of the membrane. An integrated NF-diafiltration process, involving a pre-concentration and a diafiltration step, was specifically designed for the fractionation of dye/NaCl mixtures. This loose NF membrane showed >99.7% rejection to reactive dyes (reactive blue 2 and reactive orange 16) and ca. 99.3% salt removal with ca. 2.0% dye loss after 5.0 diavolumes. However, the NF membrane experienced a 15.9% loss to methylene blue due to the lower rejection to this model cationic dye (97.2%). The current study provides important insights into dye/salt fractionation by loose NF membranes for digital ink-jet printing. © 2017 Elsevier B.V.