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Advanced reverse osmosis (RO) membranes for desalination, typically thin-film composite (TFC) membranes, have emerged as a prominent research direction to combat water scarcity. The substrate properties, such as the amine monomer adsorption capacity, are considered important for the interfacial polymerization (IP) process. Herein, inspired by Marangoni convection, a tailored dendrimer interlayer based on the plasma-treated polyethylene substrate was developed via the in-depth modification driven by surface tension gradient to precisely adjust the substrate properties. In addition, sodium dodecyl sulfate (SDS) was introduced as an additive to synergistically improve the desalination performance, and its role was reinvestigated. The quantitative experiments of amine monomer adsorption show that the substrate with in-depth modification possesses enhanced adsorption capacity. Therefore, massive amines can be enriched at the substrate surface, which can erupt and react violently in IP, thereby forming a polyamide layer with thick apparent thickness and abundant nanovoids. The RO membrane after optimization exhibits 99.19 % of rejection to NaCl and 3.87 L m−2 h−1 bar−1 of permeance, which shows good competitiveness compared with the advanced polymer-based RO membranes. This work provides constructive suggestions for the screening of interlayers to RO membranes and the application of polyethylene-based TFC membranes. [Display omitted] • In-depth dendrimer interlayer was tailored based on Marangoni convection. • The role of SDS was reinvestigated in the PE-based system. • Quantitative experiment was designed to detect the MPD adsorption at the substrate. • The novel PE-based RO membrane shows competitive desalination performance. [ABSTRACT FROM AUTHOR]

Membrane separation technologies featuring environmentally friendly and highly efficient processes have been widely adopted for sustainable development. Non-linear macromolecules, represented by aromatic poly(amidoamine) dendrimers (ArPD), have good potential for increasing the porosity of the active layer in thin-film composite (TFC) membranes. However, they are often difficult to use as the sole monomer in interfacial polymerization to prepare membranes with high separation accuracy. Herein, the DMF/H 2 O system was determined to resolve the problem of ArPD dissolution, and the behavioral differences of ArPD for different generations in film-forming were then elucidated. For G4 (the fourth generation of ArPD) -TMC (trimesoyl chloride) membranes, the good sieving performance is attributed to the relatively dense polyamide networks from interfacial polymerization, and the continuous pore channels from the tightly packed macromolecules. Therefore, the final polyamide layer shows significant heterogeneity. Moreover, a "patching" strategy was employed to further improve the separation performance. The ArPD-based membranes exhibit about 3 times higher permeance than MPD (m-phenylenediamine)-based membranes under the comparable NaCl rejection. For the repaired membrane, the water permeance reaches 3.2 L m−2 h−1 bar−1 with the NaCl rejection of about 94.9%, which is advantageous compared with reported macromolecule-based membranes. The repaired membrane also shows excellent performance in the removal of small organics in organic solvent system. For example, the methanol permeance achieves 1.5 L m−2 h−1 bar−1 with the rejection to potassium cinnamate (186.25 g mol−1) about 90.3%. This work provides a typical paradigm for the application of macromolecules in the preparation of TFC membranes. [Display omitted] • An aromatic poly(amidoamine) dendrimer (ArPD) served as the sole amine monomer to participate in IP reaction. • The active layer of G4 (the fourth generation of ArPD) -TMC membrane shows significant heterogeneity. • A "patching" strategy was used to further improve the separation performance. • ArPD-based membranes show good performance in desalination and removal of organics. [ABSTRACT FROM AUTHOR]

Polysulfoneamide (PSA) separation membranes show promising prospects for use in acidic wastewater treatment due to their outstanding acid stability. However, current PSA membranes have the disadvantages of low flux, poor NaCl rejection, and poor acid resistance of substrate. In this paper, a positively charged PSA membrane was successfully prepared by using polyethylene (PE) stretch membrane (usually used as a battery diaphragm) as the substrate, with polyethyleneimine (PEI) and naphthalene-1,3,6-trisulfonyl chloride (NTSC) as the monomers for interfacial polymerization. The acid-resistant membrane exhibits a dense structure with an average pore size of just 0.2844 nm. Consequently, the membrane exhibits superior rejection rates for monovalent and divalent metals (MgCl 2 99.15 %, CaCl 2 98.85 %, MgSO 4 94.5 %, NaCl 93.27 %), while also maintaining satisfactory flux. The membrane has excellent acid resistance, and maintains its superior separation performance after being immersed in 20 wt% H 2 SO 4 at a high temperature of 24 h. [Display omitted] • PSA acid-resistant membrane with excellent performance by using porous PE substrate. • PSA membranes show 93 % rejection for NaCl. • PSA membrane has a positively charged surface, with rejection up to 99.1 % for MgCl 2. • The differences between porous PE and PSF substrates were compared. • The influence of PEI Mw on membrane performance was discussed. [ABSTRACT FROM AUTHOR]

The escalating global demand for clean water has driven a growing interest in developing thin-film composite (TFC) membranes with high permeability and selectivity for wastewater treatment and desalination processes. Engineering polymer materials with precisely tunable properties for selective molecular separation remains a challenging step toward achieving this goal. Herein, we have fabricated a highly permselective asymmetric polyamide nanofilm with a dual-layer structure in which the bottom layer is a porous hyperbranched aromatic polyamide (HBPA) interlayer, and the top layer is a dense polyamide layer with a nanostrip structure. The HBPA porous layer was covalently assembled in situ via oxidative coupling reaction with ammonium persulfate on a polysulfone (PSF) substrate. The hydrophilic porous HBPA interlayer forms nanosized cavities that may enhance the storage and confine amine monomer diffusion, leading to the construction of a striped pattern PA nanofilm. The resulting asymmetric PA membrane exhibits excellent water permeability of 18.39 ± 1 L m−2 h−1 bar−1 (3.98 times that of control membranes) and improved divalent salt (Na 2 SO 4) rejection (≥98 %), surpassing most of the commercial and reported nanofiltration membranes. The HBPA-regulated interfacial polymerization provides a groundbreaking framework for developing high-performance membranes for precisely controlled nanofiltration. [Display omitted] • In situ covalent assembly of hyperbranched aromatic poly (amidoamine) via oxidative coupling reaction. • Hyperbranched aromatic poly (amidoamine) interlayer plays a pivotal role in regulating the IP process. • Hyperbranched aromatic poly (amidoamine) interlayer endows the TFC membranes with multi-scale morphology. • Asymmetric PA nanofilm exhibits outstanding permeability and ion separation performance. [ABSTRACT FROM AUTHOR]

The strategy of introducing a hydrophilic interlayer on the porous substrate has been widely applied in the modification of nanofiltration (NF) membranes. Herein, an environmentally friendly polycarboxylic interlayer is prepared from the mixture of catechol and sodium periodate (SP). Catechol is easy to oxidize to generate reactive o-quinones which undergoes phenolic polymerization to form covalent polymer with the carboxyl group, with the effect of SP initiation. Due to the introduction of carboxylic group, the interlayer is hydrophilic and can store more piperazine molecules to provide a more uniform platform for interfacial polymerization, which is conductive to form a thin and dense polyamide (PA) active layer. Compared with the traditional membrane, the modified thin film composite (TFC) membrane exhibits 1.7-fold of permeance (up to 15.4 ± 1 L·m−2·h−1 bar−1), maintaining a high rejection of Na 2 SO 4 (98.42 ± 1.2%). Although the TFC membrane without an interlayer tends to be thick and defective in low PIP concentration, the role of the interlayer can eliminate this limitation. Besides, the modified TFC membrane possesses a high electronegativity with the fact that isoelectric point (3.29) has been lower than that of the traditional membrane, which has the potential to separate negative organic pollutants in the wastewater treatment. • An polycarboxylic interlayer is fabricated by catechol polymerization with SP initiation. • The novel interlayer shows a high electronegativity. • The interlayer possesses the role of helping the storage of amine molecules and providing a uniform platform for interfacial polymerization reaction. • The desalination performance of the optimal novel NF membrane is enhanced. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanofiltration composite membrane shows excellent permeability and solvent resistance was prepared on PI/Noria composite ultrafiltration membrane. • Noria in PI solution can migrate to composite ultrafiltration membrane surface during non-solvent-induced phase separation and act as an interlayer, which can regulate the following interfacial polymerization. • This process omits the preparation process of the interlayer, making the preparation process simpler. • Due to the special composite surface structure, the interlayer is removed, which avoids the disadvantage of weak bonding force between the separation layer and the support layer caused by the existence of the interlayer. Organic solvent nanofiltration (OSN) membrane, a type of thin film composite (TFC) membrane, is widely used in separating organic solvents, but the low permeability of organic solvents is currently challenging to solve. This experiment used cross-linked polyimide (PI) as raw material and Noria as a nanoparticle additive to prepare a composite ultrafiltration membrane through non-solvent-induced phase separation (NIPS). Noria migrated to the composite ultrafiltration membrane surface during NIPS and acted as an interlayer, which can regulate the following interfacial polymerization. Then, the nanofiltration membrane was prepared by interfacial polymerization method using the modified PI membrane as the support layer. The experimental results showed that the hydrophilicity of the PI/Noria composite ultrafiltration membrane was significantly enhanced, in addition to a significant increase in pure water flux to 239 L m-2h-1bar−1. The methanol flux of the prepared composite nanofiltration membrane could be up to 5.472 L m-2h-1bar−1, which was twice as high as that of the unmodified composite membrane, and the G250 dye retention rate remained at over 99.6%. The nanofiltration performance is excellent and has good prospects for application in OSN. [ABSTRACT FROM AUTHOR]