Jixiao Wang

High‐Performance Membranes with Multi‐permselectivity for CO2 Separation

Multi-permselective membranes with diffusivity-selectivity, solubility-selectivity, and reactivity-selectivity for CO(2) separation are prepared by interfacial polymerization. The membranes are able to efficiently separate CO(2) from various light gases (H(2) , CH(4) and N(2) ) due to the optimized membrane structure and the comprehensive utilization of distinctions between CO(2) and light gases in size, condensability, and reactivity.

Gas separation membrane with CO2-facilitated transport highway constructed from amino carrier containing nanorods and macromolecules

The CO2-facilitated transport highway in the membrane was designed through amino carrier containing polyaniline nanorods and polyvinylamine. CO2 molecules could transfer quickly owing to the reversible reaction with amino groups. This strategy may have great inspiration for constructing ideal membrane structure and offering the possibility to fabricate highly permeable and selective membrane.

Fabrication of high-performance facilitated transport membranes for CO2 separation

At present, liquid membranes, ion-exchange membranes and fixed carrier membranes are the three popular facilitated transport membranes for CO2 separation. They possess their own advantages, as well as their respective deficiencies. In view of the characters of these three types of facilitated transport membrane, we report a method to combine their advantages and overcome their deficiencies. A new membrane was fabricated by establishing high-speed facilitated transport channels in the fixed carrier membrane. This membrane displays excellent CO2 separation performance and good stability. The results suggest that this is an effective way to fabricate high performance and high stability CO2 separation membranes. Furthermore, establishing high-speed facilitated transport channels in fixed carrier membranes will be a universal route to improve the performance of gas separation membranes.

Electrochemical synthesis of polypyrrole nanowires on composite electrode

Abstract Polypyrrole nanowires growing with two-dimensional instantaneous nucleation and one-dimensional growth pattern were realized on graphite/paraffin composite electrode in phosphate buffer solution.

High-Performance Multilayer Composite Membranes with Mussel-Inspired Polydopamine as a Versatile Molecular Bridge for CO2 Separation

It is desirable to develop high-performance composite membranes for efficient CO2 separation in CO2 capture process. Introduction of a highly permeable polydimethylsiloxane (PDMS) intermediate layer between a selective layer and a porous support has been considered as a simple but efficient way to enhance gas permeance while maintaining high gas selectivity, because the introduced intermediate layer could benefit the formation of an ultrathin defect-free selective layer owing to the circumvention of pore penetration phenomenon. However, the selection of selective layer materials is unfavorably restricted because of the low surface energy of PDMS. Various highly hydrophilic membrane materials such as amino group-rich polyvinylamine (PVAm), a representative facilitated transport membrane material for CO2 separation, could not be facilely coated over the surface of the hydrophobic PDMS intermediate layer uniformly. Inspired by the hydrophilic nature and strong adhesive ability of polydopamine (PDA), PDA was therefore selected as a versatile molecular bridge between hydrophobic PDMS and hydrophilic PVAm. The PDA coating endows a highly compatible interface between both components with a large surface energy difference via multiple-site cooperative interactions. The resulting multilayer composite membrane with a thin facilitated transport PVAm selective layer exhibits a notably enhanced CO2 permeance (1887 GPU) combined with a slightly improved CO2/N2 selectivity (83), as well as superior structural stability. Similarly, the multilayer composite membrane with a hydrophilic CO2-philic Pebax 1657 selective layer was also developed for enhanced CO2 separation performance.

A high performance antioxidative and acid resistant membrane prepared by interfacial polymerization for CO2 separation from flue gas

An antioxidative composite membrane was developed by interfacial polymerization of trimesoyl chloride and sodium 3,5-diaminobenzoate on a cross-linked polydimethylsiloxane coating polysulfone membrane. Diethylene glycol bis(3-aminopropyl) ether was added into the aqueous phase to improve CO2 permeance by the CO2-philic group, namely ether oxygen. Attenuated total reflectance-Fourier transform infrared resonance spectroscopy and scanning electron microscopy were used to characterize the composite membranes. The effects of the molar ratio of monomers in the aqueous phase and the concentrations of monomers in both the aqueous phase and the organic phase were investigated to obtain higher permselectivity. For CO2/N2 gas mixture (15/85 by volume), the optimized membrane displays a CO2 permeance of 5831 GPU and CO2/N2 selectivity of 86 at 0.11 MPa feed pressure. Moreover, the membrane shows excellent antioxidizability and acid resistance. Finally, the economic evaluation of the membranes prepared in this work for flue gas separation was carried out. A two-stage membrane system using the membrane prepared in this work shows cost-competition compared with the traditional chemical absorption method.

Self-Assembly of Aniline Oligomers

A great number of nano/microscaled morphologies have recently been prepared during the oxidation of aniline. At the early stage of oxidation, aniline oligomers are obtained, often in spectacular morphologies depending on reaction conditions. Herein, the flower-like hierarchical architectures assembled from aniline oligomers by a template-free method are reported. Their formation process is ascribed to the self-assembly of oligoanilines through non-covalent interactions, such as hydrogen bonding, hydrophobic forces, and π-π stacking. The model of directional growth is offered to explain the formation of petal-like objects and, subsequently, flowers. In order to investigate the chemical structure of the oligomers, a series of characterizations have been carried out, such as matrix-assisted laser desorption ionization, time-of-flight mass spectrometry, gas chromatography coupled with mass spectrometry analysis, X-ray diffraction, and UV/Vis, Fourier-transform infrared, and Raman spectroscopies. Based on the results of characterization methods, a formation mechanism for aniline oligomers and their self-assembly is proposed.

An antioxidative composite membrane with the carboxylate group as a fixed carrier for CO2 separation from flue gas

A novel composite membrane merely with the carboxylate group as a fixed carrier for CO2 separation from oxidant-containing flue gases was developed. The obtained membrane shows excellent permselectivity and antioxidizability.

A Template‐Free Method toward Urchin‐Like Polyaniline Microspheres

Urchin-like PANI microspheres with an average diameter of 5-10 µm have been successfully prepared. Their surfaces consist of highly oriented nanofibers of ≈30 nm diameter and 1 µm length. The solvent composition plays an important role in the formation process of urchin-like PANI microspheres. The structure of the products has been characterized by FT-IR, UV-vis, and XRD. To investigate the self-assembly of urchin-like PANI microspheres, the effect of polymerization time on the morphology of the products has been studied. The morphological evolution process indicates that the urchin-like microspheres originate from the self-assembly of nanoplates, which then grow into urchin-like microstructures with nanofibers on the surface.

A novel strategy for the synthesis of sheet-like polyaniline.

Polyaniline (PANI) micro/nanosheets are successfully synthesized by a template-free method without using any conventional oxidants. Scanning electron microscopy, transmission electron microscopy, and FT-IR spectroscopy are applied to characterize the products. By investigating the morphologies and chemical structures of the PANI micro/nanosheets, a possible formation mechanism is proposed. In addition, the influences of experimental parameters, such as the kind of dopant, concentration of aniline, and acidity of reaction system, on the morphologies of the PANI micro/nanosheets have been systematically investigated.