Effect of piperazine on CO₂ loading in aqueous solutions of MDEA at low pressure

Solubilities of CO₂ in aqueous solutions of activated methyldiethanolamine (MDEA) has been investigated for temperatures and CO ₂ partial pressures ranging from 40 to 80°C and 0.1 to 100 kPa, respectively. Piperazine (PZ) is used as activator, with a concentration ranging from 0.01 to 0.1 M, keeping the amine total concentration in the aqueous solution at 2 M. The experimental solubility results were represented by the mole ratio of CO₂ per activated amine present in the liquid mixture. The addition of piperazine, as activator for MDEA, increased the solubility of CO₂ in the region of low CO₂ partial pressure compared to pure MDEA. The CO₂ loading increased with decreasing temperature, increasing CO₂ partial pressure, and increasing PZ concentration.