Abstract

Mixing a polymer matrix and nanofiller to prepare a mixed matrix membrane (MMM) is an effective method for enhancing gas separation performance. In this work, a unique UiO-66-decorated halloysite nanotubes composite material (UiO-66@HNT) was successfully synthesized via a solvothermal method and dispersed into the Pebax-1657 matrix to prepare MMMs for CO2/N2 separation. A remarkable characteristic of this MMM was that the HNT lumen provided the highway for CO2 diffusion due to the unique affinity of UiO-66 for CO2. Simultaneously, the close connection of the UiO-66 layer on the external surface of HNTs created relatively continuous pathways for gas permeation. A suite of microscopy, diffraction, and thermal techniques was used to characterize the morphology and structure of UiO-66@HNT and the membranes. As expected, the embedding UiO-66@HNT composite materials significantly improved the separation performances of the membranes. Impressively, the as-obtained membrane acquired a high CO2 permeability of 119.08 Barrer and CO2/N2 selectivity of 76.26. Additionally, the presence of UiO-66@HNT conferred good long-term stability and excellent interfacial compatibility on the MMMs. The results demonstrated that the composite filler with fast transport pathways designed in this study was an effective strategy to enhance gas separation performance of MMMs, verifying its application potential in the gas purification industry.

Highlights

  • Due to the increasing consumption of fossil fuels by humans, the concentration of carbon dioxide in the atmosphere has led to a gradual global temperature increase

  • According to the Intergovernmental Panel on Climate Change (IPCC), CO2 levels will increase to 450 ppm in 2035, which will contribute to a 2 ◦ C increase in global temperature [1]

  • CmHg−1 ), L is the thickness of the membrane, V is the volume of the permeate side of the membrane, p1 is the pressure of the feed side and p2 is the pressure of the permeate side, A is the effective membrane area, T is the absolute dp temperature (K), dt2 is pressure rise rate, and R is the ideal gas constant

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Summary

Introduction

Due to the increasing consumption of fossil fuels by humans, the concentration of carbon dioxide in the atmosphere has led to a gradual global temperature increase. MOFs have been used to great effect in a variety of applications due to their high porosity, adjustable pore structure, and rich chemical functions Due to their uniform pore diameters, MOFs are widely used for gas separations. UiO-66 was coated on HNT to create a pathway for gas transmission and accelerate CO2 into the lumen of HNT These nanotubes were embedded in the Pebax-1657 matrix to fabricate MMMs for CO2 /N2 separation. Pebax-1657 is a commercial rubbery polymer used as continuous phase with high gas permeability and selectivity. It consists of a hard segment (PA) and a soft segment (PEO). The long-term stability of the MMMs was studied in order to test their anti-aging behavior

Materials
Fabrication of MMMs of MMMs
Image of
Permeability Experiment
Maxwell Model
Results
As shown
XRD patterns
TheThe
BET Characterization of the Material
Effect of Filler Type and Content on the Gaspermeability
Comparison of the performance of other coefficients
Effect of Feed Pressure on Gas Separation Performance
Comparison with Robeson’s Upper Bound
11. Theofmembrane had stable
Conclusions

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