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• 7,7′-OH-BINOL and diacyl chloride were used to prepare TFC OSN membranes. • The formed polyarylate layer show thin and high microporosity characters. • Two oil phase cross-linker result in nanofilms with diverse microstructures. • The optimal membrane shows methanol flux of 5.81 LMH/bar and MWCO of 288 Da. In recent years, OSN technology has gained great attention for its environmental friendly nature, energy efficiency, and small carbon footprint. Herein, we prepared TFC OSN membranes BINOL-TPC and BINOL-IPC with higher selectivity by employing a contorted molecule 7,7′-dihydroxy-2,2′-binaphthol (7,7′-OH-BINOL) with four functional groups and diacyl chloride (TPC/IPC) via interfacial polymerization (IP) method compared to with trimesoyl chloride (TMC). The use of monomer 7,7′-OH-BINOL with rigid, twisted and multiple reaction sites endow the resulted polyarylate layer with high microporosity and cross-linking density. Notably, the BINOL-TPC and BINOL-IPC membranes exhibited good performance in retaining small molecular solutes, with MWCO values of 288 and 344 Da, respectively. Meanwhile, the methanol permeance of the two composite membranes reach 5.81 and 7.06 LMH/bar, respectively. In addition, the membrane BINOL-TPC could achieve precise separation of mixed dyes with similar molecular weight but opposite charge. As can be seen, by designing and utilizing IP monomers with different structures and functionalities, it is possible to fabricate membranes with diverse microstructures and properties, ultimately leading to varied separation performances. This research offers some new insights in the view of molecular-level tailoring for the fabrication of high performance OSN membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Contorted 7,7′–OH-BINOL was used as a co-monomer with PIP to prepare NF membrane. • The new NF membrane had thinner and less rough surface with enhanced microporosity. • The membrane presented enhanced water permeance and mono-/divalent salt selectivity. High-performance nanofiltration (NF) membranes prepared by interfacial polymerization (IP) are ideal choice for solving water scarcity. In this study, 7,7′-dihydroxy-2,2′-binaphthol (7,7′–OH-BINOL) with rigidly-contorted structure was used as a co-monomer with piperazine (PIP), leading to NF membranes with lower selective layer thickness and enhanced microporosity, thus facilitated the water molecules transportation. The incorporation of 7,7′–OH-BINOL could regulate the interface diffusion rate of PIP and afforded the polyesteramide selective layer with a special bowl-shaped crater surface morphology. The PIP/BINOL-TMC nanofiltration membrane with the optimal phenol/amine ratio presented water permeability of up to 17.01 L m-2 h−1 bar−1, which was more than two times that of the pristine NF membrane (i.e. PIP-TMC). Meanwhile, it displayed comparable Na 2 SO 4 rejection (∼98%) and excellent mono-/divalent salt selectivity (S NaCl/Na2SO4 = 44). In addition, long-term operation and pressure resistance test results demonstrated that the tailored membrane had good operational stability. In conclusion, this work provides a feasible way to overcome the perm-selectivity trade-off effect of NF membrane and potentially could be used to solve the water scarcity problem. [ABSTRACT FROM AUTHOR]

• The nanofilm with high microporosity was prepared from a novel Tris-Phenol monomer. • Surfactant DTAC addition improved the selectivity of the Tris-Phenol OSN membrane. • The MWCO of Tris-Phenol membrane was as low as 295 Da in solvent methanol. • It showed not only size selective mechanisum but also a charge selective behavior. As an emerging membrane separation technology, organic solvent nanofiltration (OSN) has shown great application potential in the field of pharmaceutical and chemical industries referring to organic media. Herein, we prepared a novel microporous thin-film composite (TFC) OSN membrane with superior perm-selective performances, which was fabricated by applying 4,4′,4″-trihydroxytriphenylmethane (Tris-Phenol) to react with trimesoyl chloride (TMC) by interfacial polymerization (IP) technique. The rigid, non-planar and multifunctional nature of Tris-Phenol endowed the polyarylate nanofilm with enhanced microporosity. Of note, the prepared composite membrane showed good selectivity to small organic solutes with molecular weight cut-off (MWCO) as low as ∼295 Da, meanwhile had medium methanol permeance up to 5.86 LMH/bar, by the help of surfactant dodecyl trimethyl ammonium chloridea (DTAC) during the IP reaction. The experiments showed that the Tris-Phenol membrane exhibited extraordinary long-term operation stability. In addition, the Tris-Phenol membrane could achieve separation of solutes with similar molecular weights but different charges. This research well illustrated the novel IP monomer design strategy to fabricate new TFC OSN membrane with high perm-selectivity. [ABSTRACT FROM AUTHOR]

• Novel NF membrane was fabricated from a triamine monomer PMPD with high water flux. • The PMPD combined PIP and MPD moieties in one molecule. • The pristine NF membrane was tailored to zwitterionic surface by 3-BPA. • The membrane PMPD-PA exhibited good antifouling performance. As known, piperazine (PIP) and m -phenylenediamine (MPD) are popularly employed as aqueous monomer to interfacially polymerize with trimesoyl chloride (TMC) for the fabrication of TFC polyamide NF and RO membrane, respectively. In this work, we designed a novel amine monomer 4-(piperazin-1-yl)benzene-1,3-diamine (PMPD) having the combined PIP and MPD units in one molecule and employing it with TMC to prepare the pristine nanofiltration membrane. Subsequently, zwitterionic antifouling PA surface was constructed by modification with 3-bromopropionic acid (3-BPA). The resulting membrane (PMPD-PA) exhibited a smoother surface with enhanced surface hydrophilicity than the membrane made from MPD, and the thickness of the PA active layer was down to ~35 nm. Meanwhile, its pure water permeability was ~19 L m−2 h−1 bar−1, with Na 2 SO 4 rejection of 98.4%, and NaCl rejection as low as 24.1%, performing as a novel selective NF membrane. Furthermore, fouling tests using model foulants BSA and SA well illustrated the good antifouling properties of membrane PMPD-PA with the mitigated flux decline and enhanced flux recovery upon physical cleaning. Thus, this work further demonstrates the fabrication of high-performance TFC NF membrane from the perspective of molecular design. [ABSTRACT FROM AUTHOR]

[Display omitted] • THPPO monomer has a steric structure and with multiple reactive hydroxyl groups. • The ultrathin polyester selective layer was prepared via interfacial polymerization. • The fabricated LNF membrane exhibited good dye/salt separation performance. Loose nanofiltration (LNF) membranes prepared by hydroxyl monomers with good dye rejection and inorganic salt permeation properties have attracted significant attention for treating salt-containing textile wastewater. This study adopted interfacial polymerization (IP) method to fabricate a novel polyester LNF membrane, in which tris (4-hydroxyphenyl) phosphine oxide (THPPO) with a steric structure was employed as the solely aqueous monomer. To enhance the solubility and esterification reaction activity of THPPO, sodium hydroxide (NaOH) was specially adopted in aqueous phase, helping the development of the polyester selective layer. The findings demonstrated that the prepared ultrathin (30–38 nm) polyester selective layer exhibited a smooth surface with a negative charge. The optimal membrane LNF-0.05 exhibited a good water permeance of 20.8 L m−2 h−1 bar−1, excellent rejection of anionic dyes (99.6 % for EBT, 99.3 % for CR, 98.8 % for DR 23, and 98.1 % for MB), and low rejection of monovalent salts (8.2 % for NaCl, 5.0 % for MgCl 2), showing excellent EBT/NaCl mixture selectivity as high as 221. The performance stability of the membranes was partially testified by continuous filtration process. These results confirm the significant application potential of tris-phenol phosphine oxide-based polyester LNF membrane for treating saline textile wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2,6-dipiperazine pyridine (PyBPIP) monomer was synthesized successfully. • The fabricated membrane has a PA active layer with an ultrathin thickness of ∼ 60 nm. • The resulting membrane demonstrated high heavy metal removal (Cu2+, Zn2+, Mn2+, Ni2+). • The fabricated membrane exhibits good stability in 72 h long term operational test. Nanofiltration offers a promising solution for removing heavy metal ions from wastewater, thereby mitigating ecological and environmental risks. In this study, we synthesized a novel pyridine-diamine precursor 2,6-dipiperazine pyridine (PyBPIP), and employed it as the sole aqueous monomer to fabricate tight polyamide (PA) nanofiltration (NF) membranes via interfacial polymerization (IP) method with trimesoyl chloride for the separation of heavy metals. The resulting membrane features an ultrathin PA functional layer (approximately 60 nm), a lower molecular weight cut-off of 251 Da, and a weakly negatively charged surface. This NF membrane exhibits competitive water permeance of approximately 7.67 LMH/bar and excellent rejection rates exceeding 98 % for various heavy metals ions including Zn2+, Mn2+, Cu2+, along with outstanding separation performance for other divalent cations. Additionally, the NF membrane also exhibits robust stability during the 72-h operational test. In summary, this study demonstrates the feasibility of designing suitable monomers for the preparation of highly perm-selective NF membranes for the removal of heavy metal ions in wastewater. [ABSTRACT FROM AUTHOR]