Towards a clean environment: The potential application of eco-friendly magnesia-silicate cement in CO2 sequestration. (10th April 2020) - Abdel-Gawwad, Hamdy A.
Abstract: The key point of this study is the fabrication of magnesia-based cement with promising mechanical properties and high efficiency of CO2 -capture. The naturally occurring volcanic ashes (white & red ashes) and reactive magnesium oxide are the main materials used in the synthesis of eco-friendly CO2 -capture materials. Volcanic ashes were individually mixed with reactive magnesium oxide at ash to magnesium oxide ratio of 25:75 wt %. The dry blends can react with water to yield hardened materials (at ambient temperature) with compressive strength depends on the type of volcanic ash. A considerable change in the features of the hardened samples was recorded when the fabricated materials exposed to 100% CO2 gas for 28-days. This change is mainly due to CO2 -capture by magnesium hydroxide Mg(OH)2 within the fabricated materials, resulting in the formation of Nesquehonite minerals MgCO3 .3H2 O as proved by X-ray diffraction, thermo-gravimetric, and infra-red instrumental techniques. The thermo-gravimetric analysis demonstrates that, the fabricated sample containing low amorphous red ashes has higher CO2 -capture capacity (∼260 kg/ton) compared to that having high amorphous white volcanic ashes (∼220 kg/ton) at 28-days of CO2 -exposure. Accordingly, the fabricated magnesia-based cement is not only used as cementitious material with outstanding mechanical properties, but also used as a super CO2 -absorbent precursor. This can strongly contribute in the mitigation of global warming potential caused by different industrial activities. Graphical abstract: Image 1 Highlights: Eco-friendly hardened materials with high CO2 - capture capacity has been synthesized. Two naturally volcanic ashes and reactive magnesium oxide are the main raw materials. The amorphous content plays an important role in the rate of CO2 capture. The CO2 -capture capacity by the prepared materials was ranging from 220-260 kg/ton.