Synthesis and characterization of polymeric membrane contactors for biogas upgrading: Experimental validation and AI-based performance prediction

Abstract

Biogas is a vital renewable energy source that requires the efficient separation of acid gases, such as CO₂ and H₂S, to enhance its energy value and prevent corrosion of equipment or pipelines. Gas–liquid membrane contactors (GLMCs) are emerging as the most promising option for upgrading biogas. This study aims to develop an efficient indigenous flat-sheet GLMC system for separating CO₂ from biogas using various hydrophobic porous membranes, including polyvinylidene fluoride, polyvinyl chloride, and polystyrene, using aqueous absorbents such as sodium hydroxide (NaOH) and monoethanolamine (MEA). The polymeric membranes were synthesized via the phase inversion technique and characterized for their structural and morphological properties, contact angle, surface roughness, crystallinity, and functional groups. The effects of the liquid absorbent's flow rate and concentration on CO₂ separation were also investigated. Results showed that the polystyrene membrane exhibited the highest CO₂ absorption flux of 10.71 × 10⁻² mol/m²·s when using 0.2 M NaOH as the absorbent, with constant gas and liquid flow rates of 0.4 L/min and 0.5 L/min, respectively. Furthermore, different AI models were developed using the experimental data to predict the mass transfer rate of CO₂ in the membrane contactor. A comparative assessment revealed that the extra trees regressor model was the most accurate model for predicting GLMC performance in biogas separation.