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Abstract In this study, the novel technique, namely interfacial polymerization (IP) coupled with surface amidation, was proposed to fabricate polyamide thin-film composite (TFC) membranes for improved reverse osmosis performance. TFC membrane with loose polyamide separation layer was firstly prepared through conventional IP process. Surface amidation was then performed through covering the surface of the loose polyamide layer with aqueous 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) solution. Amidation reaction between the free carboxylic and amino groups on membrane surface was confirmed through ATR-FTIR and XPS analyses. Permeation tests revealed that the step of surface amidation could effectively improve the ability of membrane rejection to solute, showing significant increases of NaCl, NaNO 3 and glycerol rejections from about 96.4%, 90.5% and 78.4% to 97.8%, 93.7% and 91.3%, respectively. The water permeability of the membrane obtained via IP followed with surface amidation was at least 22.3% higher than the membrane of the same NaCl rejection obtained via conventional IP process. Thus, the method developed was attractive for the fabrication of TFC reverse osmosis membranes with improved permeability to water and rejection ability to solutes. Additionally, the step of surface amidation of present work can be potentially applied to the in-situ rejuvenation of used polyamide reverse osmosis membranes. Highlights • TFC membrane was fabricated via interfacial polymerization and surface amidation. • Surface amidation was facilely implemented via using acidic EDC aqueous solution. • PA selective layer composed of a top dense skin on loose bulk was obtained. • PA TFC membrane with improved reverse osmosis performance could be obtained. [ABSTRACT FROM AUTHOR]

Effective oil/water separation is urgently demanded but still remains a global challenge. Membranes with super-wettability have been rapidly developed, but most of the membranes are suffered from the complicated fabrication procedures and inability of separating different types of emulsions. In this work, super-amphiphilic PVDF composite membranes were developed via synchronous in-situ growth and immobilization of Ag nanoparticles during phase inversion. This method allowed the membrane formation and nanoparticle immobilization at the same time. The impact of silver growth time on the surface morphology and wettability was comprehensively investigated. The introduction of Ag nanoparticles endowed the membranes with micro/nano-structures and super-wetting property, which made the membrane possess reversible under-liquid superamphiphobicity. The PVDF composite membranes exhibited high permeate flux and outstanding separation efficiency for different surfactant-stabilized oil/water emulsions. Moreover, the prepared membranes could be regenerated through a facile method of rinsing and drying and the high separation performance could be maintained after repeated cycles, indicating the outstanding anti-fouling performance of the membranes. Furthermore, the PVDF composite membranes exhibited superior antibacterial performance. This work made progress in fabricating super-wetting membranes with excellent emulsion separation performance and the membranes can be prospective candidate for oily-mixture separation in practical applications. [Display omitted] • Under-liquid superlyophobic PVDF membrane was successfully fabricated. • A novel synchronous in-situ growth and immobilization of Ag NPs was adopted. • The impact of Ag growth time on morphology and wettability was investigated. • The membrane could effectively separate various surfactant-stabilized emulsions. • The membrane exhibited excellent durability and anti-fouling performance. [ABSTRACT FROM AUTHOR]

In this study, heterostructured MOF/lamellar talc composites was successfully synthesized by in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles on acidified black talc (ABT) and introduced into polydimethylsiloxane (PDMS) matrix to prepare high-performance mixed matrix membranes (MMMs) via spin coating and thermal cross-linking. The submicron-size natural lamellar black talc (BT) was first explored as stable carrier to synthesize laminated composite with continuous MOF phase. Owing to its silica-oxygen tetrahedral structure, the resultant laminated composite presented good compatibility with PDMS matrix, avoiding the formation of interfacial defect between polymer and nanoparticles. Moreover, well-dispersed and continuous ZIF-8 nanoparticles on lamellar nanosheets had preferential adsorption effect for alcohol, enhancing the selectivity of membranes. The coupling effects of graphene-like lamellar structure from talc and sequential transport channels from ZIF-8 attributed to greatly enhance permeation flux. Various techniques such as FESEM, TEM, FTIR, XRD and EDS were applied to investigate the morphology and structure of composites and membranes, and pervaporation experiments were applied to probe the behavior of polymer-based composite membranes. High performance defect-free ZIF-8@ABT/PDMS MMMs exhibited excellent total permeate flux of 1711 g m−2 h−1 with very competitive separation factor of 41 for low concentration n-butanol recovery. [Display omitted] • Heterostructured composite was first achieved by in-situ growth of MOF on talc nanosheet. • MMMs were obtained by introducing lamellar composites into PDMS matrix via spin-coating. • Interfacial defect was avoided by good compatibility between ZIF-8@ABT and PDMS matrix. • Preferential adsorption and unobstructed pathway were achieved by MOFs and lamellar ABT. • Stable ZIF-8@ABT/PDMS membranes exhibited excellent performance for butanol recovery. [ABSTRACT FROM AUTHOR]

Pore size distribution is crucial for the application of nanofiltration membrane in size-selective separation of industrial fluids. In this work, a novel combined interfacial polymerization (IP) and in-situ sol-gel strategy was proposed to fabricate composite nanofiltration membrane with narrow pore size distribution. Aqueous solution of piperazine and polyvinyl alcohol (PVA) was employed to perform interfacial polymerization with organic solution of trimesoyl chloride and tetraethyl orthosilicate (TEOS) on porous support. The non-reactive additive TEOS within the interfacially synthesized selective separation layer was then employed to perform sol-gel. The space-limited hydrolysis and condensation of TEOS molecules and their chemical bonding with PVA molecules were confirmed by analyzing membrane physico-chemical property and were found to be effective in tuning mean pore diameter, narrowing the pore size distribution and thus enhancing membrane perm-selectivity. Compared to those of membrane PA1 with similar mean pore size fabricated by only IP technique, the water permeability and rejection ratio of PEG1000 to raffinose (R PEG1000 /R raffinose) of membrane PA-TEOS0.5 fabricated by combined IP and sol-gel technique were higher by 25.0 and 20.1%, respectively. Moreover, static adsorption and dynamic deposition tests using aqueous bovine serum albumin solution proved that in-situ sol-gel process could endow the membrane with better protein fouling resistance. Image 1 • A combined interfacial polymerization and in-situ sol-gel technique was proposed. • Structure of interfacailly synthesized barrier layer was tuned via in-situ sol-gel. • In-situ sol-gel led to decreased mean pore size and narrowed pore size distribution. • Membrane fabricated by the combined technique exhibited improved perm-selectivity. • In-situ sol-gel endowed the membrane with improved anti-protein-fouling property. [ABSTRACT FROM AUTHOR]

• Carbodiimide-assisted zwitterionic modification was performed with PA TFC membrane. • Irreversible depositions by dyes CR and VBB were lowered by 68.4 and 91.8 %. • Water permeabilities to CR and VBB aqueous solutions were enhanced by 62.3 and 95.2 %. • Permselectivity property was better than most of the reported zwitterionic membranes. • Separation performance to dye aqueous solutions was better than membrane NF270. In this work, a novel method of carbodiimide-assisted zwitterionic modification was proposed and implemented to incorporate zwitterionic moieties onto poly(piperazine amide) membrane for improved water permeability and anti-depositing property, which are crucial for highly efficient nanofiltration of dye-contained effluents. Carboxyl groups of polyamide layer were firstly transferred into N-acylurea using excess l-ethyl-3-(3-(dimethylamino)propyl)-carbodiimide. Zwitterions were then incorporated through ring-opening reaction between tertiary amine groups of N-acylurea and 1, 4-butanesultone. Carbodiimide-assisted zwitterionic modification was verified by ATR-IR and XPS analyses and was found to not affect membrane pore size but significantly enhance membrane's permeation and anti-dye-deposition performances. Compared with those of virgin membrane, water permeabilities of the desired zwitterionic membrane to pure water, Congo red aqueous solution and Victoria blue B aqueous solution were higher by 42.9, 62.3 and 95.2 %, respectively, hydraulic resistances from irreversible deposition of Congo red and Victoria blue B molecules were dramatically lowered by 68.4 and 91.8 %, respectively. Furthermore, the perm-selectivity performance of the desired zwitterionic membrane in terms of molecular weight cut-off and pure water permeability was better than most of the reported zwitterionic membranes, and the separation and anti-depositing performances to both anionic and cationic dye aqueous solutions were better than commercial membrane NF270. [ABSTRACT FROM AUTHOR]