Preparation of superhydrophobic PVDF membranes for CO2 absorption via a facile spraying method

Abstract

Membrane absorption represents a promising technology in carbon capture. However, its efficiency is limited by membrane wettability and mass transfer resistance. In this study, an adhesive layer was constructed on commercial membranes through the deposition of phenol-amine copolymer. Subsequently, a rapid spraying method was employed to load silica nanoparticles, complemented by fluorinated hydrophobic modification, resulting in the successful fabrication of superhydrophobic PVDF membranes. The membranes were thoroughly evaluated through a series of characterizations and CO₂ absorption experiments, focusing on surface morphology, chemical composition, wettability, roughness, and absorption flux. Comparative analysis between the three-step (S-Si-3-M) and two-step (S-Si-2-M) methods revealed the structural and performance advantages of the latter. The findings indicated that the S-Si-2-M membrane exhibited a loose, porous structure with high roughness, demonstrating superior overall performance compared to S-Si-3-M. The water contact angle for S-Si-2-M was measured at 153.1°, with a sliding angle of 8.2°, confirming its superhydrophobic characteristics. The deposition of phenol-amine rendered the membrane amino-functionalized, enhancing its CO₂ affinity. Absorption experiments revealed that the flux of S-Si-2-M significantly exceeded the pristine membrane under various absorption conditions, maintaining a stable flux of approximately 4.8 mmol m⁻² s⁻¹ over a 40-h absorption experiment, thus indicating excellent membrane absorption performance. This work offers a novel approach for the development of high-performance membrane materials in membrane CO₂ absorption.