Carbon dioxide capture using liquid absorption methods: a review

Anthropogenic emissions of greenhouse gases into the atmosphere is inducing global warming, ocean acidification, polar ice melting, rise in sea level, droughts and hurricanes, thus threatening human health and the global economy. Therefore, there is a need to develop cost-effective technologies for CO 2 capture. For instance, solution absorption is promising due to a large processing capacity, high flexibility and reliability, and rich experience in engineering applications. Nonetheless, actual commercial solutions, solvents and processes for CO 2 capture suffer from slow reaction kinetics, low absorption capacity, high-energy consumption, susceptibility to corrosion, toxicity, low stability and high costs. Therefore, current research focuses on developing more economical, effective, green and sustainable technologies. Here we review 2015–2020 findings on CO 2 capture using liquid absorption methods. Methods are based on various solutions, solvents and processes such as carbonate solution, ammonia solution, amine-based solution, ionic liquid, amino acid salt, phase changing absorbent, microcapsulated and membrane absorption, nanofluids and phenoxide salt solution. We discuss absorption performance, absorption mechanism, enhancement pathways and challenges. Amine- and NH 3 -based absorbents are widely used, yet they are limited by high regeneration energy, corrosiveness and degradation, reagent loss and secondary pollution caused by NH 3 escape. Phase changing absorbents are getting more attention due to their lower cost and lower energy penalty. The incorporation of membrane and microencapsulation technologies to absorbing solvents could enhance CO 2 absorption performance by reducing corrosion and increasing selectivity. Adding nanoparticles to solvents could improve CO 2 absorption performance and reduce energy requirement. Besides, solvent blends and promoter-improved solvents performed better than single and non-promoted solvents because they combine the benefits of individual solvents and promoters.