2.1.1 Absorption
It refers to the process by which one substance, such as a solid or liquid, takes up another substance, such as a liquid or gas, through minute pores or spaces between its molecules. The absorption capacity of the absorber depends on the equilibrium concentrations between gaseous phase and the liquid phase. For diluted concentrations in many gases and in a wide interval of concentrations, the equilibrium relation is given by Henry’s Law, which quantifies the gas absorption capacity in the fluid (Cengel & Boles, 2008). A gas absorbing unit should ensure complete contact between the gas and the solvent, in such a way that diffusion occurs at the inter-phase.