Rapid Self-Assembly of Oligo(<i>o</i>-phenylenediamine) into One-Dimensional Structures through a Facile Reprecipitation Route

The self-assembly of oligo(o-phenylenediamine) (OPD) into 1-D nanostructures on a macroscopic length scale was found when they were transferred from N-methyl pyrrolidone to deionized water. Field emission scanning electron microscopy and confocal fluorescence microscopy were used to investigate the morphology of the precipitates. Results showed that large amounts of OPD 1-D supertructures could be obtained through the simple reprecipitation route, and the length of the fibers could be tuned from microscale to macroscale by adjusting the ratio of two solvents. X-ray diffraction patterns and UV−vis spectra revealed that π−π interactions between OPD molecules that facilitated the formation of 1-D structures became predominant when they were transferred from a good solvent to a bad one. Accordingly, a possible formation mechanism was proposed

Solar-Intensified Ultrafiltration System Based on Porous Photothermal Membrane for Efficient Water Treatment

Membrane separation is widely regarded as a promising technology for water treatment. To run the membrane at the optimal conditions, preheating of feedwater before being sent into the membrane unit is often employed, which results in high energy consumption. Here we report a multifunctional system that combines traditional pressure-driven membrane filtration with solar thermal technology based on a photothermal membrane for high-efficiency water treatment. The multifunctional membrane consists of multiwalled carbon nanotubes and polysulfone (MWCNT-PSf), which not only facilitates the water permeation through the membrane but also effectively heats the feed solution by sustainable solar energy. The composite membrane containing MWCNT demonstrates excellent light absorption of 94% over the full solar spectrum range, which can effectively preheat the feedwater. With the assistance of light irradiation, the MWCNT-PSf photothermal membrane exhibits high water flux over 314 L m–2 h–1 with a rejection above 95% for coomassie brilliant blue at 0.10 MPa, which is 101.3% higher than that without light irradiation. The solar-intensified ultrafiltration system based on a porous photothermal membrane provides a new avenue to treat wastewater or seawater

Dual-Modulated Polyamide Membranes Based on Vapor–Liquid Interfacial Polymerization for CO₂ Separation

Polyamide (PA) membranes show great application potential in the CO2 separation study. However, the PA membranes prepared by the traditional interfacial polymerization (IP) have a dense microstructure and a singularity of functional groups, making it difficult to exhibit both high CO2 permeance and selectivity. Herein, we report a new dual-modulation strategy by preparation method optimization and filler modification to improve the CO2 separation performance of the PA membranes. The PA membranes prepared by vapor–liquid IP have a loose microstructure, which greatly improves the gas permeance. The introduction of mono-(6-ethanediamine-6-deoxy)-beta-cyclodextrin (CD) can better loosen the PA microstructure, and the CO2-philic groups in the CD boost the CO2 selectivity by the facilitated transport effect. Ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate is further sealed into PA membranes to remedy the possible microvoids or defects and CD cavities of the membrane microstructure. The prepared membranes display excellent CO2 separation performance with CO2/H2, CO2/CH4, and CO2/N2 selectivity of 8.2, 45.5, and 116.9, as well as a CO2 permeance of about 320 GPU. The proposed strategy provides a facile and effective route to dual-modulated PA membranes for the study of CO2 separation and can be expanded to other macrocyclic molecules and ionic liquid systems

Codoping Strategy To Improve Stability and Permeability of Ba_0.6Sr_0.4FeO_3−δ-Based Perovskite Membranes

To improve the stability and oxygen permeability of Ba_0.6Sr_0.4FeO_3−δ (BSF)-based perovskite membranes, an Mg and Zr codoping strategy is proposed. The characterization by X-ray diffraction, Mössbauer spectroscopy and oxygen permeation measurements revealed that single-element Mg doping could improve the oxygen permeability of BSF-based membranes. However, in situ XRD measurements indicated that the single-element Mg doping exhibits a poor thermal stability at low oxygen partial pressure. Single-element Zr doping could improve the structure stability of BSF-based perovskites but lead to a serious decrease of oxygen permeability. Compared with the BSF-based perovskites doped by either Mg or Zr alone, Mg and Zr codoped perovskite Ba_0.6Sr_0.4Fe_0.8Mg_0.15Zr_0.05O_3−δ showed a better stability than single-element Mg doping and exhibited a higher oxygen permeability than single-element Zr doping. For the Mg and Zr codoped BSF, the oxygen permeation flux reached 0.78 mL min^–1 cm^–2 at 950 °C under an air/He oxygen partial pressure gradient

Temperature-Induced Structural Reorganization of W‑Doped Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ Composite Membranes for Air Separation

The practical use of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) prototypical oxygen-transport membrane for air separation is currently hampered by the decomposition of the cubic perovskite into a variant with hexagonal stacking at intermediate temperatures of ≤850 °C, which impairs the oxygen transport. Here, we report the development of a W-doped BSCF composite that contains Fe-rich single perovskite (SP) and W-rich double perovskite (DP) phases with different crystallographic parameters. In contrast to BSCF, the BSCFW SP/DP composite maintains its cubic structure at 800 °C for 200 h, demonstrating its structural stability at intermediate temperatures. We use X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy to show that the enhanced phase stability of the composite is associated with a temperature-induced SP–DP dynamic interaction, which involves W and Fe interdiffusion between the SP and DP phases, dynamically adjusting the chemical composition and limiting structural distortion and new phase formation. The composite exhibits a stable permeation performance in the oxygen-transport membrane during over 150 h operation at 800 and 700 °C, confirming the potential of intermediate-temperature oxygen-transport membranes for air separation and providing insight for designing thermally stable composite oxides

Single-Hole Hollow Carbon Nanospheres via a Poly(ethylene glycol)-Assisted Emulsion-Templating Strategy for Intensified Liquid-Phase Adsorption

Single-hole hollow carbon nanospheres (HCH) possess unique properties that combine the advantages of a hollow cavity and an opening hole in the shell, making them very attractive in various applications. However, it is still a challenge to synthesize HCH via a facile and scalable route. Herein, we develop a poly­(ethylene glycol) (PEG)-assisted emulsion-templating method to synthesize HCH, involving only a hydrothermal process and pyrolysis. In the emulsion system, the PEG molecules can be used as a reverse demulsifier to induce the formation of hollow structures with a closed shell (HCS, PEG-1000), a single hole in the shell (HCH, PEG-2000), and a bowl-like shell (HCB, PEG-4000). It is found that HCH exhibits higher adsorption capacities (2–4 times higher than those of HCS) and faster adsorption rates toward large molecules (e.g., Congo red), indicating the intensification of liquid-phase adsorption induced by the single-hole hollow structure, which can promote mass transfer and simultaneously enhance the adsorption capacity