Towards a clean environment: The potential application of eco-friendly magnesia-silicate cement in CO2 sequestration

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 MgCO3.3H2O 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. [Display omitted] •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.