Absorption of carbon dioxide by raw and treated dye-bath effluents

A bench-scale experimental apparatus, consisting of a glass column randomly packed with cylindrical glass rings, was utilized for the removal of carbon dioxide (CO2) by chemical absorption. Various liquid solvents were used, in a batch mode, circulating between the column and a reservoir vessel, and contacting the gas in counter current flow. The absorptive capacity of the liquid solvents and the absorption kinetics were studied by obtaining the respective 'breakthrough curves'. Aqueous solutions of sodium hydroxide (NaOH) were initially utilized in order to demonstrate the experimental apparatus function. Dye-bath effluent proved highly effective due to its high alkalinity and the capacity of the hydrolyzed “azo-reactive” dyes to react with CO2. Decolorized dye-bath effluent (treated with FeSO4) can also be used as a chemical solvent for the absorption of CO2; however, its absorptive capacity is much lower compared to the raw wastewater. The above technique is also a very effective method to neutralize industrial effluents.