Reaction Mechanism for the Aqueous-Phase Mineral Carbonation of Heat-Activated Serpentine at Low Temperatures and Pressures in Flue Gas Conditions

• Published in: Environmental science & technology Vol. 48; no. 9; pp. 5163 - 5170
• Main Authors: Pasquier, Louis-César, Mercier, Guy, Blais, Jean-François, Cecchi, Emmanuelle, Kentish, Sandra
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.05.2014
• Subjects: Applied sciences; Aqueous solutions; Asbestos, Serpentine - chemistry; Carbon dioxide; Carbon Dioxide - chemistry; Climatology. Bioclimatology. Climate change; Cold Temperature; Dissolution; Earth, ocean, space; Emissions; Exact sciences and technology; External geophysics; Flue gas; Gases - chemistry; Hot Temperature; Meteorology; Microscopy, Electron, Scanning; Minerals; Minerals - chemistry; Mining; Other industrial wastes. Sewage sludge; Pollution; Pressure; Reaction kinetics; Scanning electron microscopy; Temperature; Wastes; Water - chemistry; Carbon dioxide; CO2 sequestration; Carbon sequestration; beneficiation; industrial waste; greenhouse gas; sustainable development; Mitigation; Geoengineering; Thermal activation; Waste reuse; Reaction mechanism; Carbonation; Emissions reduction; waste management; Mining industry; climate change
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es405449v

Mineral carbonation is known as one of the safest ways to sequester CO2. Nevertheless, the slow kinetics and low carbonation rates constitute a major barrier for any possible industrial application. To date, no studies have focused on reacting serpentinite with a relatively low partial pressure of CO2 (p CO2 ) close to flue gas conditions. In this work, finely ground and heat-treated serpentinite [Mg3Si2O5(OH)4] extracted from mining residues was reacted with a 18.2 vol % CO2 gas stream at moderate global pressures to investigate the effect on CO2 solubility and Mg leaching. Serpentinite dissolution rates were also measured to define the rate-limiting step. Successive batches of gas were contacted with the same serpentinite to identify surface-limiting factors using scanning electron microscopy (SEM) analysis. Investigation of the serpentinite carbonation reaction mechanisms under conditions close to a direct flue gas treatment showed that increased dissolution rates could be achieved relative to prior work, with an average Mg dissolution rate of 3.55 × 10–11 mol cm–2 s–1. This study provides another perspective of the feasibility of applying a mineral carbonation process to reduce industrial greenhouse gas (GHG) emissions from large emission sources.