Cellulose-driven supported liquid membranes with (choline chloride)-based deep eutectic solvents for CO2 separation from biogas

1 Cellulose-driven supported liquid membranes with (choline chloride)-based deep eutectic solvents for CO2 separation from biogas Gorka Marco Velasco 3rd International Online Conference on Polymer Science Gorka Marco Velasco 21/11/2025 2 In Materials, Technology and Sustainability (MATS) group, we focus on several lines of research: oDesign and application (bio)polymer and composite membrane materials. oSynthesis of ionic liquids and deep eutectic solvents as catalyzers and reaction environment. oValorization of plastic residues by mechanic, chemical, thermal and biological processes. oDevelopment of biorefinery processes from farming and forest residues. Introduction: MATS lines of research Gorka Marco Velasco 3rd International Online Conference on Polymer Science València, Spain 3 To address current climate challenges, Carbon Capture and Storage (CCS) applications have drawn great interest to palliate greenhouse gases (GHG) emission. In this respect, polymer membranes have become an emergent and technically viable CCS technique. Polymer membranes still present constraints when compared with traditional CCS processes, especially regarding green membrane materials. However, they can be enhanced by the incorporation of liquid additives within the polymeric structure such as ionic liquids or deep eutectic solvents (DES), forming supported liquid membranes (SLMs).These present a higher CO2 absorption capacity and selectivity when compared with bare polymeric membranes. Context Source: Islam et al. (2021) Porous support Liquid additive Gorka Marco Velasco 3rd International Online Conference on Polymer Science 4 DESs are mixtures formed by a hydrogen bond acceptor (HBA) and donor (HBD). Hydrogen bonds reduce the melting temperature of the mixture, and it becomes a homogeneous liquid phase. DES present an extreme tunability due to the wide variety of existing HBAs and HBDs and the different molar ratios of the mixture. DES are suitable additives to incorporate into a polymeric matrix due to their cost-effectiveness, availability and their unique physicochemical properties, including: Low vapor pressure Very low toxicity Biodegradability Context Gorka Marco Velasco 3rd International Online Conference on Polymer Science Source: Marco-Velasco, G., Gálvez-Subiela, A., Jiménez-Robles, R., Izquierdo, M., Cháfer, A., & Badia, J. D. (2024). A Review on the Application of Deep Eutectic Solvents in Polymer-Based Membrane Preparation for Environmental Separation Technologies. Polymers, 16(18), 2604. 5 Traditional membrane materials such as poly(vinylidene fluoride) (PVDF), poly(tetrafluoroethylene) (PTFE) or poly(ether sulfone) (PES), among others have been widely reported in literature. However, more sustainable options can be considered to perform membrane-based environmental applications. Cellulose-based membranes have been widely used in water treatment applications. However, CCS purposes remain underexplored. For this work, three DES were used to form DES-based supported liquid membranes (DSLMs) based on cellulose polymer substrates. DSLMs were characterized and tested in CO2and CH4permeability experiments. Context Gorka Marco Velasco 3rd International Online Conference on Polymer Science PVDF PTFE Cellulose-based materials R = COO, NO3 or OH 6 Three different cellulose-based flat-sheet polymer substrates were used. Regenerated cellulose (RC) (Whatman®, Cytiva, UK), Cellulose nitrate (CN) (Dorsan, Barcelona, Spain) and cellulose acetate (CA) (CHMLab, Barcelona, Spain). Materials and methods DESs Cellulose Vacuum DSLMs production Three different DESs were fabricated to produce DSLMs: Choline Chloride : Urea in 1:2 molar ratio (ChCl:U 1:2). Choline Chloride : Glycerol in 1:2 molar ratio (ChCl:Gly 1:2). Choline Chloride : Malic Acid in 2:1 molar ratio (ChCl:MalAc 2:1). Avacuum assisted method was used to immobilize the DES into the polymeric matrix. The resulting DSLMs had an average of 70 %wt content of DES. Gorka Marco Velasco 3rd International Online Conference on Polymer Science Key Concepts DES fabrication method 80ºC 250 rpm Cool at Troom HBA HBD DES + 7 DSLMs permeability of pure gas CH4or CO2was obtained by single-gas permeability tests under atmospheric pressure and room temperature. AHe sweep gas flow rate of 1 mL min-1 was applied in the permeate side of the membrane module to eliminate the flow of permeated gases. Materials and methods Gas concentrations on the permeate side of the membrane were obtained by gas chromatography. Ultimately, CO2/CH4 selectivity was calculated. Gorka Marco Velasco 3rd International Online Conference on Polymer Science DESs Cellulose Vacuum DSLMs production Key Concepts Permeability tests CO2 CO2/CH4 CH4 3. Field emission scanning electron microscopy (FE-SEM): To observe morphology changes on the DSLMs (S) and cross-sections (CS) with respect RC, CN and CA pristine membranes. 8 Materials and methods 2. Energy dispersive X-ray analysis (EDX): For analysis of the most relevant chemical elements of each DSLM. 1. Fourier Transform Infrared spectroscopy (FTIR): This technique assessed the presence of ChCl:U 1:2, ChCl:Gly 1:2 or ChCl:MalAc 2:1 DESs in the RC, CN and CA supports. Characterization techniques Gorka Marco Velasco 3rd International Online Conference on Polymer Science DESs Cellulose Vacuum DSLMs production Key Concepts Permeability tests CO2 CO2/CH4 CH4 SEM FTIR EDX Characterization Results and discussion: Characterization 9 Fourier transform infrared spectroscopy (FTIR) All matrices 3400 cm 1: O H stretching 2900 cm 1: C H stretching 1370 cm 1: CH3stretching 1050 cm 1: C O C stretching Regenerated cellulose (RC) bare membrane mainly present these bands. Cellulose nitrate (CN) 1641 cm 1: NO2anti-symmetric stretching 1276 cm 1: NO2symmetric stretching 832 cm 1: NO stretching Cellulose acetate (CA) 1740 cm 1: C = O stretching 1225 cm 1: C O acetyl group stretching Gorka Marco Velasco 3rd International Online Conference on Polymer Science Results and discussion: Characterization 10 Fourier transform infrared spectroscopy (FTIR) Gorka Marco Velasco 3rd International Online Conference on Polymer Science For all RC membranes 3400 cm 1: O H stretching 2900 cm 1: C H stretching 1370 cm 1: CH3stretching 1050 cm 1: C O C stretching Choline Chloride (ChCl) 1470 cm 1: C H anti-symmetric deformation 960 cm 1: deformation Urea (U) 1680 cm 1: C=O stretching (amide carbonyl) 1630 cm 1: N H bending 1450 cm 1: C N stretching Glycerol (Gly) does not present additional bands Malic Acid (MalAc) 1720 cm 1: C=O stretching (organic acid) Regenerated cellulose (RC) DSLMs Results and discussion: Characterization 11 Fourier transform infrared spectroscopy (FTIR) Gorka Marco Velasco 3rd International Online Conference on Polymer Science For all CN membranes 3400 cm 1: O H stretching 2900 cm 1: C H stretching 1641 cm 1: NO2anti-symmetric stretching 1370 cm 1: CH3stretching 1276 cm 1: NO2symmetric stretching 1050 cm 1: C O C stretching 832 cm 1: NO stretching Choline Chloride (ChCl) 1470 cm 1: C H anti-symmetric deformation 960 cm 1: deformation Urea (U) 1680 cm 1: C=O stretching (amide carbonyl) 1630 cm 1: N H bending 1450 cm 1: C N stretching Glycerol (Gly) does not present additional bands Malic Acid (MalAc) 1720 cm 1: C=O stretching (organic acid) Cellulose nitrate (CN) DSLMs Results and discussion: Characterization 12 Fourier transform infrared spectroscopy (FTIR) Gorka Marco Velasco 3rd International Online Conference on Polymer Science For all CA membranes 3400 cm 1: O H stretching 2900 cm 1: C H stretching 1740 cm 1: C = O stretching 1370 cm 1: CH3stretching 1225 cm 1: C O acetyl group stretching 1050 cm 1: C O C stretching Choline Chloride (ChCl) 1470 cm 1: C H anti-symmetric deformation 960 cm 1: deformation Urea (U) 1680 cm 1: C=O stretching (amide carbonyl) 1630 cm 1: N H bending 1450 cm 1: C N stretching Cellulose acetate (CA) DSLMs 13 Energy dispersive X-ray analysis (EDX) % wt. RC ChCl:U 1:2 DSLM ChCl:Gly 1:2 DSLM ChCl:MalAc 2:1 DSLM C 50.95 49.94 61.72 66.39 N - 6.79 < d.l. < d.l. O 48.25 29.08 28.86 22.93 Cl - 14.18 9.42 10.68 Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science % wt. CN ChCl:U 1:2 DSLM ChCl:Gly 1:2 DSLM ChCl:MalAc 2:1 DSLM C 33.52 42.99 47.79 54.69 N 13.30 11.53 5.69 < d.l. O 53.18 38.31 38.06 38.69 Cl - 7.17 8.46 6.62 % wt. CA ChCl:U 1:2 DSLM C 55.95 56.98 N - 5.01 O 44.05 26.64 Cl - 11.37 Analyses were performed on cross-section Cl content indicated the presence of choline chloride (ChCl) C content increased as DES were immobilized d.l.: detection limits 14 Scanning Electron Microscopy (SEM): x500 (Cross-section) and x1,000 (Surface) magnifications ChCl:U 1:2 Surface ChCl:MalAc 2:1 Surface ChCl:Gly 1:2 Surface ChCl:U 1:2 Cross-section ChCl:Gly 1:2 Cross-section ChCl:MalAc 2:1 Cross-section 50 µm Pristine RC Cross-section Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science 50 µm Pristine RC Surface 50 µm 50 µm 50 µm 50 µm 50 µm 50 µm Dense morphology was obtained after DES immobilization in both cross-section and surface images. 15 Scanning Electron Microscopy (SEM): x4,000 magnifications ChCl:U 1:2 Surface ChCl:MalAc 2:1 Surface ChCl:Gly 1:2 Surface ChCl:U 1:2 Cross-section ChCl:Gly 1:2 Cross-section ChCl:MalAc 2:1 Cross-section 50 µm Pristine RC Cross-section Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science 50 µm Pristine RC Surface 50 µm 50 µm 50 µm 50 µm 50 µm 50 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm Dense morphology was obtained after DES immobilization in both cross-section and surface images. 16 Scanning Electron Microscopy (SEM) x500 (Cross-section) and x1,000 (Surface) magnifications ChCl:U 1:2 Surface ChCl:MalAc 2:1 Surface ChCl:Gly 1:2 Surface ChCl:U 1:2 Cross-section ChCl:Gly 1:2 Cross-section ChCl:MalAc 2:1 Cross-section Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science 50 µm Pristine CN Cross-section 50 µm Pristine CN Surface 50 µm 50 µm 50 µm 50 µm 50 µm 50 µm Dense morphology was obtained after DES immobilization in both cross-section and surface images. 17 Scanning Electron Microscopy (SEM): x4,000 magnifications ChCl:U 1:2 Surface ChCl:MalAc 2:1 Surface ChCl:Gly 1:2 Surface ChCl:U 1:2 Cross-section ChCl:Gly 1:2 Cross-section ChCl:MalAc 2:1 Cross-section 50 µm Pristine CN Cross-section Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science 50 µm Pristine CN Surface 50 µm 50 µm 50 µm 50 µm 50 µm 50 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm 10 µm Dense morphology was obtained after DES immobilization in both cross-section and surface images. 18 Scanning Electron Microscopy (SEM) : x500 (Cross Section) and x1,000 (Surface) magnifications ChCl:U 1:2 Surface ChCl:U 1:2 Cross-section 50 µm CA Surface 50 µm CA Cross-section Results and discussion: Characterization Gorka Marco Velasco 3rd International Online Conference on Polymer Science 50 µm 50 µm Dense morphology was obtained after DES immobilization in both cross-section and surface images.