Functionalized organic filler based integrated membranes for environmental remediation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Global environmental concerns necessitate efficient carbon dioxide (CO2) separation technologies.
• Mixed matrix membranes (MMMs) offer a promising approach by combining the properties of polymers and functional fillers.
• Nitrogen-rich, CO2-philic fillers can enhance CO2 separation performance in MMMs.

Purpose of the Study:

• To synthesize and characterize mixed matrix membranes (MMMs) using varying loadings of porphyrin poly(N-isopropyl Acryl Amide) (P-NIPAM) as functionalized organic fillers within a polysulfone (PSU) matrix.
• To evaluate the CO2 separation efficiency of these MMMs through pure and mixed gas permeation studies.
• To analyze the performance of the MMMs against established benchmarks, such as Robeson's upper bound, and to model their gas permeation behavior.

Main Methods:

• Solution casting was employed to fabricate MMMs with P-NIPAM fillers (5-20%) in a PSU matrix.
• Characterization techniques included field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), and Fourier Transform Infrared Spectrometer (FT-IR).
• Pure and mixed gas permeation experiments were conducted under feed pressures ranging from 2 to 10 bar.

Main Results:

• MMMs exhibited well-distributed fillers, homogenous surfaces, and cross-sectional structures due to favorable organic species interactions (π-π interactions, Lewis basic functionalities).
• The MMMs demonstrated superior CO2/CH4 and CO2/N2 separation performance, exceeding Robeson's upper bound.
• CO2/CH4 permeability improved to 88.2 ± 0.9 Barrer, and CO2/N2 permeability reached 75 ± 0.8 Barrer, with selectivities of 85% for both gas pairs.
• The modified Maxwell-Wagner-Sillar model accurately predicted CO2 permeabilities with a low average absolute relative error (AARE%) of 0.87%.

Conclusions:

• The developed MMMs, incorporating functionalized P-PNIPAM, show exceptional CO2 separation capabilities due to the filler's affinitive properties.
• These membranes represent a significant advancement in CO2 capture technology for anthropogenic sources.
• While promising, the cost analysis indicated that membrane production costs for industrial setups using indigenous resources remain a consideration for scalability.