Shiwei Tian,Yaqi Zhang,Qiankun Sha,Tian Yang,Yan Huang,Xingxiang Zhang,Wei Wang,Na Han
Highly efficient treatment of oil-water emulsions in severe environments (organic solvents, strong acids) is recognized as a challenging subject. Polyphenylene sulfide (PPS) is an ideal membrane material with superior thermal stability as well as chemical resistance that is expected to settle this challenge. However, the hydrophobicity of PPS (h-PPS) membrane inherently prevents its efficient treatment of oil-in-water (O/W) emulsions. In this study, superhydrophilic modification of PPS substrates was achieved by in situ electrostatic self-assembly of hydrophilic Zr-MOFs to obtain UiO-66-NH 2 @h-PPS membranes. The introduction of UiO-66-NH 2 crystals constructed the micro/nanoscale hierarchical structure for the substrate, which transforms the PPS substrate from a hydrophobic to a superhydrophilic state (water droplets require only 0.6 s to be completely immersed in the membrane). Meanwhile, the UiO-66-NH 2 @h-PPS membranes gain under-water superhydrophobicity (the under-water oil contact angle exceeds 150° for toluene, hexane , dichloromethane , and carbon tetrachloride , of which toluene reaches 163.1°), thereby improving wettability selectivity and decreasing oil adhesion, permitting the fabricated UiO-66-NH 2 @h-PPS membranes to effectively separate different types of O/W emulsions. The UiO-66-NH 2 @h-PPS membranes acquire excellent permeate fluxes (for the surfactant-free toluene-in-water emulsion, it reaches up to 7638.1 L m −2 h −1 ) and separation accuracy (99.1% oil rejection). Moreover, the UiO-66-NH 2 @h-PPS membrane exhibited outstanding harsh environment resistance. Interestingly, the combination of UiO-66-NH 2 and h-PPS substrate was applicable to degrade the organic compound in water, and the degradation efficiency of the methylene blue achieved 85.7% under visible light within 120 min. In summary, loading Zr-MOFs onto h-PPS substrates provides a novel strategy for the efficient treatment of wastewater under complex conditions with great potential for practical applications.
Shiwei Tian,Yaqi Zhang,Qiankun Sha,Xingxiang Zhang,Tian Yang,Xuhuan Yan,Na Han
Polyphenylene sulfide (PPS) microporous membranes have garnered extensive research enthusiasm concerning their outstanding permeation performance and separation accuracy in treating oily wastewater. Nevertheless, the inherent hydrophobic chemical structure, along with the noticeable concentration polarization effect, predisposes them to severe membrane contamination during the separation process. Accordingly, it is desirable to design a PPS self-cleaning membrane with superior anti-fouling capability, fast transport, and remarkable flux recovery. This study marks the first combination of PPS membrane materials with the photo-Fenton process. In detail, the polyphenol (tannic acid, TA)-polycation (polyethyleneimine, PEI)-metal ion (Fe 3+ ) double cross-linking coatings were first assembled on the PPS substrate surface. Subsequently, β-FeOOH photocatalysts were synthesized through in-situ mineralization to further strengthen the hydrophilicity of the membranes. The obtained PPS/TA-PEI/β-FeOOH composite membrane achieved exceptional separation of diverse oil-in-water (O/W) emulsions. The PPS/TA-PEI/β-FeOOH membranes exhibited in-air superhydrophilic and under-water superoleophobicity, exhibiting under-water oil contact angles greater than 151° for diverse oil agents. The fabricated composite membranes displayed high permeability (a flux of the petroleum ether-in-water (P/W) emulsion reached 3400.5 L m −2 h −1 bar −1 driven by a pressure of 0.05 MPa) along with ideal oil rejection (98.6 %). Significantly, the PPS/TA-PEI/β-FeOOH membrane possessed powerful photo-Fenton self-cleaning capability, and its flux recoveries of the contaminated membrane exceeded 90.3 % for varied O/W emulsions after being cleaned by visible light for 10 min. We believe that our research presents a novel approach for the exploitation of PPS-based photo-Fenton self-cleaning membranes, which also exhibit great applicative potential in oily wastewater treatment.
Porous PPS membranes are commonly employed to separate the released gases in conventional alkaline electrolyzers. However, their poor ionic conductivity and high gas permeability bring up the issues of high energy consumption and rapidly raised safety risks when the electrolyzers operate at high-pressure levels. Therefore, it is of great significance to develop alternative membranes with superior conductivity and gas tightness. In this study, we prepared an ultrathin composite membrane with support layer via combination of hot-pressing and phase inversion precipitation techniques. The comprehensive performances of the prepared membranes, commercial PPS fabric and commercial Zirfon membrane were compared. The cell performance of the prepared membranes and commercial membranes at high current density was also evaluated. The ultrathin composite membrane exhibits lower cell voltage and ionic resistance than commercial membranes. With the introduction of support layer, the tensile strength of the prepared ultrathin composite membrane significantly increased by 19 times.
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