CO2 capture and conversion by an organosilane-modified cementitious material

Abstract Alkali-activated fly ash (AFA) could be modified by 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (TRI). The successful modification of fly ash beads by TRI was confirmed by IR spectra and 29Si NMR, the TG-DSC results showed that 18.42671 g TRI was loaded on 100 g AFA. The TRI-modified AFA (TRI-AFA) showed strong sorption for CO2, which was confirmed by GC, and it could incorporate into cement to make a new kind of cementitious material. This kind of cementitious material also showed strong sorption for CO2. Upon immersion of the sample in water, the absorbed CO2 could be converted into CO32− due to the alkali environment in the pore solution of the cement, and the sample was then recovered. The recovered sample maintained 85% capacity for CO2 sorption after 10 cycles. Thus, the sample could reversibly absorb and desorb CO2, and could potentially help in reducing greenhouse gases.