Alkali-treated titanium dioxide as adsorbent for CO2 capture from air

Abstract

The novel TiO2-based adsorbents exhibiting high CO2 capture efficiency were prepared through modification of a crude TiO2 obtained by sulfate technology, with NH4OH and/or KOH solutions of various concentrations. The prepared adsorbents were characterized by N2 adsorption–desorption at 77K, X-ray diffraction and elemental analysis. The morphology of the samples was observed with scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). The results revealed that the modification of TiO2 with alkali solutions is a simple and efficient method of preparation of CO2 sorbents with high adsorption capacity. The co-modification of TiO2 with NH4OH and KOH allowed to increase the total adsorption capacity from 0.06mmol CO2/g in case of crude TiO2 to 0.53mmol CO2/g in case of the most efficient co-modified sample (TiO2–2.5%N/10%K). The adsorption properties of the materials were not only influenced by their textural characteristics, but also related to the surface chemistry, which was affected by the type of the modifying agent and the concentration of the modification solutions.