Green-Synthesized HF-free MIL-100(Fe) Nanoparticle-Infused Chitosan Mixed-Matrix Membranes for Enhanced CO₂ Permeance

Abstract

The green synthesis route for producing mixed-matrix membranes (MMMs) has recently received a lot of attention to capture CO 2 from the gaseous mixture. Taking this into consideration, biopolymer chitosan (CS) was selected as a matrix and MIL-100(Fe) nanoparticles (NPs) as the nanofiller, which was created using an hydrofluoric acid (HF)-free environment at ambient conditions. The advantages of the zwitterion mechanism via amine groups of CS and the high surface area and CO 2 affinity via open-metal sites of MIL-100(Fe) NPs were exploited in the study. A solution casting approach was employed to fabricate the active layer of filler-embedded CS solution with a desired thickness of ∼1 to 1.5 μm onto the poly(ether sulfone) (PES) support. The effect of MOF addition on the chemical, physical, and thermal structure of synthesized MMMs was studied by utilizing various analytical techniques and compared with the pristine CS membrane. At optimum operating conditions of 2.21 bar feed pressure and 85 °C temperature under swollen circumstances, the pure CS membrane showed CO 2 /N 2 selectivity of 29 and CO 2 permeance of 24 gas permeation units (GPU). Under similar operating conditions, the optimized MMM demonstrated enhanced CO 2 /N 2 selectivity and permeance of 59 and 85 GPU, respectively. Finally, when the obtained results were compared to the axis of the Robeson diagram, the performance of the polymer/MOF membranes containing 15 wt % MOF was shown to be more suitable for separating CO 2 from N 2, even at adverse conditions.