Qing Fang,Qin Liu,Zongli Xie,Matthew R. Hill,Kaisong Zhang
Solvent-resistant nanofiltration membranes , capable of breaking “trade-off” between permeability and selectivity while resisting physical aging, hold crucial utility in developing advanced membrane materials and reducing energy consumption associated with solvent recovery. Herein, the development of scalable, mixed matrix membranes (MMMs) was presented based on polysulfone (PSf) substrate with ultra-high permeability and aging resistance. The upper selective layer was composed of poly-trimethylsilylpropyne (PTMSP) and two types of nano-fillers, namely poly-dichloroxylene ( p -DCX) and sodium dodecylbenzene sulfonate-molybdenum sulfide (SDBS-MoS 2 ). Under the influence of the additives, the redistribution of the free volume of the polymer as well as the internal spaces within additives creates additional pathways for solvent diffusion, thus increasing solvent permeance. Additionally, the combined effect of the two additives is likely to inhibit filler agglomeration and improve the overall effectiveness of the additives. Compared to pure PTMSP membranes, the p -DCX/SDBS-MoS 2 PTMSP MMMs exhibited enhanced methanol permeance (10.58 vs. 3.14 L m −2 h −1 bar −1 ) and RB rejection (99.23 vs. 96.13 %), which greatly exceeded that of current OSN MMMs. As anticipated, aging of the prepared membranes decelerated with the addition of the additives, and the methanol permeation loss rate decreased from 50.32 % to 13.23 % after 300 h. Molecular dynamics simulations explored by structural analysis revealed the mechanism for the significant improvement in methanol permeance and aging resistance. The membranes obtained were found to be highly industrially applicable, thereby offering the potential to reduce operation costs in energy-intensive separation processes.
Feipeng Wang,Jian Zhou,Linyang Dan,Yihua Qian,Shi Li,Issouf Fofana,Massimo Pompili,Jian Li
The oil-paper insulation system in eco-friendly fire-retardant transformers depends on hydrophilic natural ester insulating oil. Moisture within the system synergistically interacts with aging, worsening oil-paper insulation degradation and hastening overall system aging. Chemical vapor deposition was used to create parylene surface-modified insulating paper as a strategy to inhibit moisture-induced aging in natural ester oil-paper insulation. The effectiveness of the approach was identified by a comprehensive assessment of the physicochemical and electrical properties of the parylene surface-modified insulating paper. The findings from accelerated thermal aging at 130 °C for 90 days on the natural ester oil-paper insulation system reveal the outstanding lipophilic and hydrophobic properties while maintaining electrical characteristics of the parylene surface-modified insulating paper. After 90 days of aging, the parylene surface-modified insulating paper exhibited a 56.76 % higher degree of polymerization and a 19.36 % significantly lower moisture content than conventional cellulose insulating paper. In the natural ester oil-paper insulation system, the parylene surface-modified insulating paper led to a notable 63 % reduction in insulating oil acid value, a 60.50 % decrease in dielectric loss, and a substantial 20.35 % increase in AC breakdown voltage. Molecular-level investigations revealed the inhibitory mechanism of the parylene film, offering a promising solution to enhance the thermal stability and aging resistance of natural ester oil-paper insulation systems.
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