Kai Huang,Xiao Quan,Xipeng Li,F. Handan Tezel,Baoan Li
Organic fouling has been a major impediment for the widespread application of nanofiltration membranes because it could degrade the performance and shorten the service life of such membranes. In this study, the NH 2 -functionalized silica nanoparticles (NH 2 –SiO 2 NPs) were grafted on the surface of commercial NF90 membrane to improve the hydrophilicity and antifouling property with the N -(3-dimethylaminopropyl)- N -ethylcarbodiimide hydrochloride coupled with the N -hydroxysuccinimide (EDC/NHS) to activate carboxyl groups on the membrane surface. The surface roughness (Ra) of this modified membrane decreased from value of 47.4 nm of the pristine membrane to 43 nm. The water contact angle of the modified membrane decreased from 48.4° to 15°, indicating the high hydrophilicity of the surface. Moreover, the EDC/NHS membrane showed good stability when it was exposed to the ruinous physical stress (2-min sonication). The optimized grafting conditions, including the SiO 2 concentration (0.5 wt%), the activation time of EDC/NHS (20 min), and the reaction time of NH 2 –SiO 2 NPs with membrane surface (12 h), were obtained by a series of experiments. Under the antifouling test of 36 hours with bovine serum albumin (BSA) and hexadecyltrimethylammonium bromide (CTAB) as foulants, the EDC/NHS membrane lost 42.1% and 49.6% of its initial flux, respectively, which is lower than that of the pristine membrane (52.2% and 68%, respectively). After cleaning with deionized water for 2 hours, the EDC/NHS membrane also showed significant improvement of flux recovery ratio (92% and 87%, respectively) than did the pristine membrane (70.3% and 60%, respectively).
Novel Fe3O4/polyimide (PI) composite films with extraordinary dielectric properties were prepared via in situ polymerization of PI in the presence of 4,4′-diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA) and compatible amine-functionalized carbon-coated Fe3O4 nanoparticles (Fe3O4@C–NH2). Fe3O4 nanoparticles prepared via solvothermal reaction were coated with crosslinked glucose and then surface-grafted via carbodiimide coupling. The core–shell structure of Fe3O4@C–NH2 was thereafter obtained with amine functionalities on the carbonized-glucose shell. Homogeneous dispersion of Fe3O4@C–NH2 and strong interfacial covalent bonding on the shell surface contributed to high dielectric constants (ε) and extremely low dielectric losses (tan δ) in the composite films. The highest dielectric constant of the composite films was 58.6 at 1 kHz when the Fe3O4@C–NH2 composition was 1.13 vol%, as well as a low dielectric loss of 0.0091 and a high breakdown strength of 126.5 ± 11.3 MV m−1 were observed without considerable sacrifice of the thermal stability and mechanical properties.
危险品化学品经营许可证（带存储）