This study investigates the removal of CO₂ from a gas mixture using sodium hydroxide in a laboratory-scale spray dryer. A gas stream containing 1.4% v/v CO₂ was treated with aqueous NaOH solutions at concentrations of 3 wt.%, 7 wt.%, and 9 wt.%. The study evaluated the impact of inlet gas temperatures ranging from 140°C to 170°C and aqueous solution flow rates between 21 ml/min and 39.6 ml/min. Gas-phase CO₂ at the dryer outlet was monitored and used to fit a time-dependent apparent first-order model fitted directly to the integrated solution by nonlinear least squares. The two-parameter model predicted the reaction rate with high R² (0.97–0.99). Higher inlet gas temperature and increased aqueous solution flow rate improved CO₂ removal under the tested conditions, and an intermediate NaOH concentration (7 wt.%) gave the best performance. Kinetic analysis returned an activation energy of 41.57 kJ/mol for the initial uptake term (K₁), while the decay term (K₂) showed weak temperature dependence with an activation energy of 3.13 kJ/mol. These findings show the feasibility of using spray drying technology for carbon capture while providing essential kinetic parameters for process scaling.

Keywords

Spray drying, sodium hydroxide, CO₂ capture, kinetic modelling, reaction rate, Arrhenius equation.