Carbon dioxide removal from triethanolamine solution using living microalgae-loofah biocomposites

Nowadays, the climate change crisis is an urgent matter in which carbon dioxide (CO₂) is a major greenhouse gas contributing to global warming. Amine solvents are commonly used for CO₂ capture with high efficiency and absorption rates. However, solvent regeneration consumes an extensive amount of energy. One of alternative approaches is amine regeneration through microalgae. Recently, living biocomposites, intensifying traditional suspended cultivation, have been developed. With this technology, immobilizing microalgae on biocompatible materials with binder outperformed the suspended system in terms of CO₂ capture rates. In this study, living microalgae-loofah biocomposites with immobilized Scenedesmus acuminatus TISTR 8457 using 5%v/v acrylic medium were tested to remove CO₂ from CO₂-rich triethanolamine (TEA) solutions. The test using 1 M TEA at various CO₂ loading ratios (0.2, 0.4, 0.6, and 0.8 mol CO₂/mol TEA) demonstrated that the biocomposites achieved CO₂ removal rates 3 to 5 times higher than the suspended cell system over 28 days, with the highest removal observed at the 1 M with 0.4 mol CO₂/mol TEA (4.34 ± 0.20 g_CO2/g_biomass). This study triggers a new exploration of integration between biological and chemical processes that could elevate the traditional amine-based CO₂ capture capabilities. Nevertheless, pilot-scale investigations are necessary to confirm the biocomposites's efficiency.