Fecha de publicación: 16/10/2024 Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Biogas separation using CNC/PVA-LA hollow fiber facilitated transport membranes.


Abstract
The composition of biogas consists mainly of CH4 (~60%) and CO2 (40%). To be considered a clean fuel, CH4 concentration in biogas must be increased to over 95%. In this study, membranes which were stacked in a chamber were utilized to purify biogas by passing biogas over them. These membranes were composed of polyethersulfone hollow fiber substrate coated with a “selective layer” made of cellulose nanocrystals (CNC-0–2 wt) in polyvinyl alcohol (PVA) and l-arginine as a CO2 carrier. Of the different CNC concentrations in PVA-LA, CNC1/PVA-LA (1.0 wt% CNC in PVA-LA) displayed the lowest water contact angle of 17° (corresponding to higher moisture absorbing ability). With further increase in CNC concentration, even though CNC1.5/PVA-LA showed the higher crystallinity (66%), and water contact angle increased (20°); reducing the chances of facilitated transport of CO2 through it. Biogas separation experiments were conducted at 90% RH and different feed pressures (0.8–1 bar) for various CNC concentrations. Increasing the CNC concentration led to a thicker selective layer, enhancing the CO2 permeability and selectivity up to CNC1/PVA-LA. However, with the further addition of CNC, both permeability and selectivity decreased. At 90% RH and 1 bar feed pressure, the CNC1/PVA-LA setup demonstrated a CO2 permeability of 20,522 Barrer and a selectivity of 33, making it suitable for low-pressure biogas storage systems with lower energy requirements.