Synergistic promotion for CO2 absorption and solvent regeneration by fine waste red mud particles on in amine-based carbon capture: Performance and mechanism

Using waste red mud as catalysts for enhancing mass transfer and boosting amine-based solvent regeneration is a promising option for both resources recycling and efficient carbon capture. Here, the effect of fine red mud particles was firstly investigated on carbon dioxide (CO 2 ) absorption and desorption. The Brownian motion and shuttle effect of submicron or micron red mud particles play a positive role in reducing the concentration boundary layer and updating the CO 2 -species concentration of liquid/gas film, which is beneficial for mass transfer enhancement. Additionally, the composite metal oxides of red mud support abundant acid/base active sites for water dissociation, which can promote the proton transfer and boost carbamate decomposition. Therefore, the average enhancement factor is ∼1.49 and the average absorption rate increases by 22.8 %; while the maximal desorption rate (2.14 mmol/min) increases by 289 % and relative heat duty decreases by 16.3 %, after adding 2.5–5 % red mud particles. The continuous CO 2 absorption–desorption experiments verify red mud increases the capture efficiency from 51.6 % (blank test) to 62.4 %. The results offer a favorable technology for reuse of industrial solid waste in the field for low-energy carbon capture.