Polyvinylidene fluoride/palygorskite composite ultrafiltration membranes
PVDF/palygorskite composite ultrafiltration membranes: Effects of nano-clay particles on membrane structure and properties
Dongyang Wei, Shouyong Zhou*, MeishengLi, Ailian Xue, Yan Zhang, Yijiang Zhao**, JingZhong, Dawei Yang.
Applied Clay Science, 181(2019), 105171
Palygorskite (PGS) was incorporated into a polyvinylidene fluoride (PVDF) matrix and PVDF/PGS nanocomposite UF membranes were prepared successfully via a combination of non-solvent-induced phase separation (NIPS) and thermally-induced phase separation (TIPS) processes. The influence of the size of the PGS particles (PGS-L, 450 nm and PGS-S, 302 nm) on the membrane pore structure, morphology, mechanical strength, filtration performance and antifouling property were investigated. The results showed that the PVDF/PGS-S composite membranes had higher porosity and lower overall membrane thickness and skin layer thickness. This directly resulted in better PWF, BSA flux, BSA rejection and FRR for the membranes loaded with PGS-S, when compared with the characteristics of PVDF/PGS-L membranes. Thus, the physical structures are dominant factors in determining the separation performance of PVDF/PGS composite membranes. However, the surface roughness and thermal stability of PVDF/PGS-L membranes were greater than those of PVDF/PGS-S membranes and their surface was also more hydrophilic. Moreover, they exhibited higher mechanical strength owing to stronger binding forces and lower porosity. Thus, the composite properties of PVDF/PGS UF membranes could be adjusted by controlling the scale of the inorganic filler.
Graphical abstractLink: https://www.sciencedirect.com/science/article/abs/pii/S0169131719302297
PVDF mixed matrix ultrafiltration membrane incorporated with deformed rebar-like Fe3O4–palygorskite nanocomposites to enhance strength and antifouling properties
Jiayun Zhu, Shouyong Zhou*, Meisheng Li, Ailian Xue, Yijiang Zhao* *, Wenbo Peng, Weihong Xing.
Journal of Membrane Science 612 (2020) 118467.
A novel PVDF mixed matrix ultrafiltration membrane was prepared by blending PVDF with the deformed rebar-like Fe3O4–palygorskite nanocomposites (MPGS) using the chemical coprecipitation method. Fe3O4 nanoparticles were anchored on the surface of the palygorskite nanofibers to form deformed rebar-like structures. MPGS were then distributed uniformly on the membrane matrix. PVDF chains firmly wrapped by the deformed rebar-like nanocomposites consequently enhanced the tensile strength of the PVDF membrane. At 7.0 wt. % MPGS, the tensile strength increased from 1.59 MPa to 2.66 MPa. The overall thickness, skin layer thickness, finger-like voids, average pore size and surface roughness of membranes decreased with increasing amounts of MPGS. The rejection of the membrane increased to 99.09% at 7.0 wt. % MPGS. The contact angle of membranes decreased from 99.14° (pure PVDF) to 78.76° (PVDF/7.0 wt. % MPGS). On the other hand, the pure water flux of membranes increased from 123.57 L·m-2·h-1 (pure PVDF) to 356.16 L·m-2·h-1 (PVDF/7.0 wt. % MPGS). The flux recovery rate of the mixed matrix membranes (PVDF/7.0 wt. % MPGS) was as high as 80%. This was more than twice that of the pure PVDF membrane (31.6%). These results demonstrated that the deformed rebar-like structure of the MPGS played a critical role in determining the structures and properties of PVDF mixed matrix ultrafiltration membranes. The hydrophilicity, thermal stability, permeation flux and antifouling property of the mixed matrix membranes increased with addition of MPGS. As such, PVDF/MPGS membranes had excellent comprehensive properties thus making them ideal for application in numerous fields.
(SY ZHOU 2021.02.05供稿）