In this study, a carbon nanotubes composite coated with N-isopropylacrylamide hydrogel (NIPAM-CNTs) was synthesized. Mixed-matrix membranes (MMMs) were fabricated by incorporating NIPAM-CNTs composite filler into poly(ether-block-amide) (Pebax MH 1657) matrix for efficient CO separation. The as-prepared NIPAM-CNTs composite filler mainly plays two roles: (i) The extraordinary smooth one-dimensional nanochannels of CNTs act as the highways to accelerate CO transport through membranes, increasing CO permeability; (ii) The NIPAM hydrogel layer coated on the outer walls of CNTs acts as the super water absorbent to increase water content of membranes, appealing both CO permeability and CO/gas selectivity. MMM containing 5 wt % NIPAM-CNTs exhibited the highest CO permeability of 567 barrer, CO/CH selectivity of 35, and CO/N selectivity of 70, transcending 2008 Robeson upper bound line. The improved CO separation performance of MMMs is mainly attributed to the construction of the efficient CO transport pathways by NIPAM-CNTs. Thus, MMMs incorporated with NIPAM-CNTs composite filler can be used as an excellent membrane material for efficient CO separation.
Ultrathin
microporous nanosheets denoted as Zn-tetra-(4-carboxyphenyl)porphyrin
(Zn-TCPP) were synthesized and incorporated into a Pebax MH 1657 (Pebax)
polymer to fabricate mixed matrix membranes (MMMs) for efficient CO2 separation. The Zn-TCPP nanosheets with a microporous structure
provide high-speed channels for fast CO2 transport and
shorten the diffusion pathways, both contributing toward high CO2 permeability. Furthermore, scanning electron microscopy results
indicate that the ultrathin Zn-TCPP nanosheets with an ultrahigh aspect
ratio (>200) tend to arrange horizontally in the Pebax matrix.
The
obtained unique cross-sectional structure of the MMMs functions as
a selective barrier, allowing repeated discrimination of gases due
to the tortuous interlayer of horizontal nanosheets, thus improving
the selectivity of the MMMs. In addition, the horizontally arranged
microporous nanosheets were found to strongly interact with the membrane
matrix and endowed the MMMs with excellent interfacial compatibility,
which improved the CO2 permeability and eliminated unselective
permeation pathways. Significantly, the optimized CO2 separation
performance of the MMMs surpassed the 2008 Robeson’s limit.
To improve CO 2 separation performance in mixed matrix membranes (MMMs), a novel mesoporous silica-coated on the outer surface of multi-walled carbon nanotube (MWCNTs@mSiO 2 ) core@shell filler was synthesized and dispersed into Pebax MH 1657 (TPE) matrix. The introduced mSiO 2 layer on the outer surface of MWCNTs have a favorable effect on the dispersion and compatibility of MWCNTs@mSiO 2 core@shell filler in TPE matrix. Most importantly, the pore channels of mesoporous silica and MWCNTs constructed the feasible gas transport pathways for CO 2 permeation in MMMs. The MMMs presented the best CO 2 separation performance when the content of MWCNTs@mSiO 2 in TPE matrix was 10 wt%. The CO 2 permeability and CO 2 /CH 4 selectivity of TPE-MWCNTs@mSiO 2 -10 membrane were 379 Barrer and 39 for CO 2 /CH 4 mixed-gas, respectively. The CO 2 permeability and CO 2 /N 2 selectivity of TPE-MWCNTs@mSiO 2 -10 membrane were 364 Barrer and 58 for CO 2 /N 2 mixedgas, respectively. POLYM. COMPOS., 00:000-000,
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