Citation: Ciulla, M.; Canale, V.; Wolicki, R.D.; Pilato, S.; Bruni, P.; Ferrari, S.; Siani, G.; Fontana, A.; Di Profio, P. Enhanced CO 2 Capture by Sorption on Electrospun Poly (Methyl Methacrylate). Separations 2023, 10, 505. https://doi.org/10.3390/ separations10090505 Academic Editor: Moises Bastos-Neto Received: 3 August 2023 Revised: 1 September 2023 Accepted: 8 September 2023 Published: 14 September 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). separations Article Enhanced CO 2 Capture by Sorption on Electrospun Poly (Methyl Methacrylate) Michele Ciulla , Valentino Canale , Rafal D. Wolicki, Serena Pilato , Pantaleone Bruni , Stefania Ferrari , Gabriella Siani , Antonella Fontana and Pietro Di Profio * Department of Pharmacy, University of Chieti-Pescara “G. d’Annunzio”, via dei Vestini, I-66100 Chieti, Italy; michele.ciulla@unich.it (M.C.) * Correspondence: pietro.diprofio@unich.it Abstract: Poly(methyl methacrylate) (PMMA) is characterized by high CO 2 capture yield under mild pressures and temperatures. A morphological modification of powdery amorphous PMMA (pPMMA) is carried out by electrospinning to increase the surface/volume ratio of the resulting electrospun PMMAs (ePMMAs). This modification improves the kinetics and the capture yields. The rate constants observed for ePMMAs are two to three times higher than those for pPMMA, reaching 90% saturation values within 5–7 s. The amount of sorbed CO 2 is up to eleven times higher for ePMMAs at 1 ◦ C, and the highest difference in captured CO 2 amount is observed at the lowest tested pressure of 1 MPa. The operating life of the ePMMAs shows a 5% yield loss after ten consecutive runs, indicating good durability. Spent electrospun PMMAs after several cycles of CO 2 sorption-desorption can be regenerated by melting and again electrospinning the molten mass, resulting in a CO 2 capture performance that is undistinguishable from that observed with fresh ePMMA. Scanning electron and atomic force microscopies show a reduction in surface roughness after gas exposure, possibly due to the plasticization effect of CO 2 . This study shows the potential of electrospun PMMAs as solid sorbents for carbon capture from natural gas or pre-combustion and oxyfuel combustion processes. Keywords: CO 2 capture; solid sorbents; poly (methyl methacrylate); polymer plasticization; electrospinning; natural gas 1. Introduction Climate change has become one of the most alarming issues that our society ever faced, urging the development of green alternatives to fossil fuels. However, the transition to fully renewable energy sources is slow, and the combustion of oil and gas is still the main source of our energy needs. In this scenario, it is crucial to develop efficient and sustainable technologies for Carbon Capture and Storage (CCS), which relates to the body of technologies devised to capture anthropogenic carbon dioxide. These techniques can be roughly divided into (i) post-combustion capture, where the gas is captured at the end of a combustion process; (ii) pre-combustion capture, where the fossil fuel is partially oxidized in order to form a syngas mix, and CO 2 is then separated therefrom; (iii) oxy-fuel combustion, where the fossil fuel is burned into an oxygen-enriched atmosphere, thus increasing the amount of CO 2 produced and making the process of extraction easier [1,2]. At present, the most advanced technologies relating to CO 2 mitigation are focused on post-combustion processes, where the flue gas is processed for CO 2 removal under low pressures. Traditional methods for CO 2 capture under ambient pressures are based on amine-based solvents. In comparison to other capture methods, the employment of chemical absorption through amines in post-combustion settings can directly extract carbon dioxide from flue gas, and is readily adapted to common power plants [3]. However, other CO 2 -containing gas mixtures (e.g., pre-combustion and oxyfuel combustion, as well as natural gas) are processed under higher pressures, where polymeric membranes Separations 2023, 10, 505. https://doi.org/10.3390/separations10090505 https://www.mdpi.com/journal/separations