Fig. 3.
Raman spectra of solutions at different times. The indicated times are the periods when samples were taken during absorption and desorption tests for Raman spectrum analysis. The peak intensities are proportional to the concentration of species in solution. a CO2 absorption without TiO(OH)2, b CO2 absorption with TiO(OH)2, c CO2 desorption without TiO(OH)2, d CO2 desorption with TiO(OH)2. Absorption conditions—total mass of solution: 200 g; MEA concentration in the solution: 20 wt%; total flow rate of gas: 1000 mL/min; composition of gas: 10 vol% CO2, 10 vol% O2, and 80 vol% N2; temperature: 25 °C; absorption time: 6000 s. Desorption conditions–total mass of solution: 200 g; MEA concentration in the solution: 20 wt%; temperature: 88 °C; time: 2400 s