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Effective fractionation of dyes and salts (NaCl) potentially paves a new path to sustainable treatment of textile wastewater. Herein, a loose nanofiltration (NF) membrane was innovatively used as the anion conductive membrane in electrodialysis (ED) for dye and salt separation. The NF membrane with a molecular weight cut-off of 678 Da showed a sufficient retention for reactive dyes with small molecular weights (<627 Da) predominantly based on synergistic effect of steric repulsion and Donnan repulsion. Simultaneously, the NF membrane had a considerably fast transport for anions (i.e., Cl−), as its loose surface structure created extra nano-channels for ion transfer. The anion conductive loose NF membrane based ED process yielded excellent separation performance in a one-step dye/NaCl fractionation. Specifically, a 98.9% desalination efficiency was obtained by the loose NF-based ED process along with 99.4% dye recovery. Additionally, an extremely low fouling propensity was observed during a 5-cycle ED operation, as the negative surface charge of the loose NF membrane served as an intrinsic barrier to prevent the dye species from entering the membrane pores through electrostatic repulsion. This study demonstrated a desirable potential of loose NF membranes as anion conductive membranes in ED for resource recovery from highly-saline wastewater. Image 1 1. Loose nanofiltration (NF)-based electrodialysis (ED) was used for dye/salt separation 2. Loose NF membrane shows an excellent ion transport as anion conductive membrane 3. Loose NF-based ED yields 98.9% desalination efficiency and 99.4% dye recovery 4. Low fouling propensity is observed for loose NF membrane as anion conductive membrane [ABSTRACT FROM AUTHOR]

• Mussel-inspired co-deposition was used to effectively tailor the surface property of NF membrane. • The modified NF membrane yielded a molecular weight cut-off of 305 Da after 90-min co-deposition. • The modified NF membrane showed enhanced fractionation of humic substances (HS) and salts. • NF-based diafiltration enriched and purified the HS from landfill leachate concentrate for sustainability. During the disposal of highly saline wastewaters, i.e., landfill leachate concentrate, a conceptual and paradigmatic transformation from contaminant elimination to sustainable resource extraction urges for novel selective membranes. Mussel-inspired modification through dopamine self-polymerization can be a competitive alternative to tailor the membrane surface properties for enhanced permselectivity to target compounds. Herein, co-deposition of polydopamine-polyethylenimine (PEI) complex onto loose nanofiltration (NF) membranes was conducted using persulfate as trigger, which resulted in a significant alteration in membrane surface properties. Particularly, the pore size of bio-inspired NF membranes decreased, along with a reduction in molecular weight cut-off (MWCO) from 640 to 298 Da after 120-min bio-inspired coating, which yielded an enhancement in rejection of humic substances from 95.1% to 98.9% in filtration of landfill leachate concentrate. Furthermore, the charge of membrane surface was tailored to be more positive due to incorporation of positively-charged PEI, which markedly undermined the electrostatic repulsion force for enhanced salt permeation. These bio-inspired NF membranes showed a superior selectivity between humic substances and salts for their potential fractionation from the landfill leachate concentrate. Through an integrated NF-based diafiltration procedure, the concentration of humic substances was remarkably enriched from 1779.4 to 17247.1 mg·L−1 with 96.0% recovery. Additionally, 99.5% desalination efficiency was achieved, resulting in a high purity (i.e., 98.3%) for humic substances as potential organic fertilizer application. These findings suggest that the bio-inspired co-deposition is an effective strategy to tailor the surface properties of NF membranes for efficient fractionation of humic substances and salts, in view of sustainable resource recovery from the landfill leachate concentrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid co-deposition of dopamine and APTS was used to construct superhydrophilic membranes. • Superhydrophilic membrane had an effective oil repellency with underwater oil contact angle of ∼163.5°. • Superhydrophilic membrane has a fast gravity-driven filtration for oil-in-water emulsions with a separation efficiency of >99.9 % • Incorporation of Cu NPs and polydopamine enables the membranes with complete antibacterial activity. Substantial discharge of industrial oily wastewater calls for an efficient and sustainable treatment for resource recovery. Superwetting membranes offer a feasible approach to fractionate oil species and water from oily wastewater for addressing this technical challenge. In this study, we proposed a useful strategy for constructing a superhydrophilic membrane with superior antibacterial properties through rapid co-deposition of dopamine and 3-aminopropyltriethoxysilane (APTS) initiated by ammonium persulfate on the Cu nanoparticles-loaded porous PVDF substrate. The resultant superhydrophilic membrane yielded an underwater oil contact angle of 163.5°, enabling a fast and robust gravity-driven filtration for various oil-in-water emulsions with a separation efficiency of >99.9 %. Additionally, incorporating of Cu nanoparticles and polydopamine endowed the superhydrophilic membrane with superior antibacterial activity (100 % inhibition efficiency against Escherichia coli), and thereby remarkably enhancing the anti-biofouling performance. This study provides a viable approach to design high-performance membranes for separation of oil-in-water emulsions, with promising applications in the industrial and environmental sectors. [ABSTRACT FROM AUTHOR]