Zhu Xiong,Yun Zhong,Haibo Lin,Fu Liu,Tiantian Li,Jinglong Li
In this work, a feasible and efficient approach was developed to produce Poly(lactic acid (PLA) ultrafiltration membrane with both high permeability and high rejection simultaneously. Poly(L-lactic acid)/Poly(D-lactic acid) (PDLA/PLLA) stereocomplex crystallites were thought to play the critical role different from the traditional pore forming agents or hydrophilic modification. The membrane morphology of the stereocomplex PDLA/PLLA membrane with high porosity and thin skin layer was observed by SEM. The addition of PDLA resulted in the thermodynamic enhancement for phase separation of PLLA casting solution as demonstrated by a rotational rheometer. The PDLA/PLLA stereocomplex crystallization behavior was investigated by DSC and XRD . With increasing the stereocomplex crystallites, the water permeability of PLA membrane significantly increased from ~482 L/m 2 ·h to ~3325 L/m 2 h, while with small loss in degree of rejection. Furthermore, the stereocomplex PLA membrane demonstrated the excellent separation efficiency for nano-TiO 2 and ink dispersion. Besides, the stereocomplex PLA membrane exhibited outstanding anti-protein fouling properties through the static and dynamic BSA antifouling tests. All results demonstrated that the stereocomplexation can effectively tune the pore size evolution and control the permeability, selectivity and fouling resistance.
Yun Zhong,Tiantian Li,Haibo Lin,Lei Zhang,Zhu Xiong,Qile Fang,Guoying Zhang,Fu Liu
In this work, we report the continuous flowing catalysis of meso-/macro-porous microspheres confining Au nanoparticles based on Poly ( l -lactic acid)/Poly (D-lactic acid) (PDLA/PLLA) stereo-complex membrane. Plentiful meso-/macro-porous microspheres (1–2 µm diameter) were assembled inside the stereo-complex Poly(lactic acid) (PLA) membrane through the phase inversion, which were thought to play a critical role on robustly capturing and confining Au nanoparticles (30–40 nm diameter) with the loading content of 1.56 g/m 2 , as demonstrated by the SEM, TEM, EDX and XPS. The Au nanoparticles-loaded stereo-complex PLA membrane exhibits an instantaneous reduction for 4-nitrophenol in a continuous flowing operation with the dynamic reactive constant 386 min −1 under the water flux of 262.8–1440 L/m 2 ·h, which was ∼2900 fold higher than the static catalytic. Moreover, the catalytic membrane keeps above 90% conversion even after 140 min continuous flowing. In addition, The Au nanoparticles-loaded stereo-complex PLA membrane demonstrated the better bovine serum albumin (BSA) antifouling and ink colloid rejection. All results verified that the stereo-complex PLA membrane provided a feasible platform for meso-/macro-porous microspheres confining Au nanoparticles as high efficient heterogeneous catalysts. The proposed strategy could be extended to other robust heterogeneous catalysts for membrane catalytic applications.
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