Microwave-assisted desorption of CO2 from ethanolamine solvent in a porous hollow fiber membrane

Chemical absorption using amine-based solvents is perhaps the most mature technology currently available for CO₂ capture. However, its widespread deployment is hindered by design constraints and high operational costs. Recent research has focused on alternative approaches for gas absorption, such as the use of hollow fiber membranes (HFMs) as gas–liquid contactors, and microwave (MW) heating as an alternative energy source for solvent regeneration. This work aims to combine HFMs and MW heating to regenerate spent alkanolamine solvents at atmospheric condition. To this end, an experimental study was conducted in which a single porous hollow fiber membrane was placed inside a custom applicator providing a homogeneous MW field. The solvent was circulated through the lumen of the hollow fiber while being heated by MW irradiation. Desorption rates were evaluated using a two-factor design of experiments (DoE), with the solvent outlet temperature varying between 50 and 60 °C, as well as the solvent and sweep gas flow rates. The desorption fluxes obtained ranged from 0.08 to 0.4 mmol.m −2 s −1 . Comparison of the desorption fluxes obtained with data from the literature showed that microwave regeneration was at least three times more efficient than the results of studies using vacuum regeneration, despite operating at a solvent temperature 10 °C lower. In order to perform a comparative analysis with data from the literature using conventional membrane contactor heating and N 2 -sweeping, the regression equation (DoE) was applied to estimate the lower limits of the desorption flux obtained under MW irradiation, at temperatures higher than those explored experimentally in this work. The extrapolated results predict MW regeneration performances equivalent to, or less than 60% of those of membrane desorption systems maintained in isothermal conditions, as reported in the literature. This study is intended to be complemented by a subsequent part dedicated to the development of a numerical model describing the tested HFM–MW desorption system.