Capture of carbon dioxide by amine-loaded as-synthesized TiO2 nanotubes.

Titanium-based adsorbents for CO2 capture were prepared through impregnating the as-synthesized TiO2 nanotubes (TiNT) with four kinds of amines, namely monoethanolamine (MEA), ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The resultant samples were characterized by X-ray diffraction, low-temperature N2 adsorption as well as transmission electron microscopy. The absorption of CO2 was carried out in a dynamic packed column. The sample impregnated with TEPA showed a better adsorption capacity due to its higher amino groups content. In addition, CO2 adsorption capacity increases as the amount of amine loaded increases. Therefore, TiNT-TEPA-69 showed the highest CO2 adsorption capacity among the three samples impregnated with TETA; approximately 4.10 mmol/g at 30 degrees C. In addition, the dynamic adsorption/desorption performance was investigated. The adsorption capacity of TiNT-TEPA-69 dropped slightly (about 2%) during a total of five cycles. The TiNT-TEPA-69 adsorbent exhibited excellent CO2 adsorption/desorption performance.