Reaction mechanism for the aqueous-phase mineral carbonation of heat-activated serpentine at low temperatures and pressures in flue gas conditions

Environ Sci Technol. 2014 May 6;48(9):5163-70. doi: 10.1021/es405449v. Epub 2014 Apr 8.

Abstract

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 (pCO2) 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asbestos, Serpentine / chemistry*
  • Carbon Dioxide / chemistry*
  • Cold Temperature
  • Gases / chemistry*
  • Hot Temperature
  • Microscopy, Electron, Scanning
  • Minerals / chemistry*
  • Mining
  • Pressure
  • Water / chemistry*

Substances

  • Asbestos, Serpentine
  • Gases
  • Minerals
  • Water
  • Carbon Dioxide