A method to enhance the CO2 storage capacity of pyroxenitic rocks

Abstract

Investigation of new efficient pathways for CO2 sequestration is of great significance for the mitigation of climate change. Ultramafic rocks are considered among the most promising lithotypes for the safe storage of CO2 via mineral carbonation. This paper investigates a powerful method for the optimization of the ex situ carbonation of pyroxenitic rocks, which comprise part of ultramafic lithologies occurring in ophiolite complexes. The ball milling process was applied to a sample of pyroxenite from the Troodos ophiolite (Cyprus) for the first time, in order to create novel nanomaterials with enhanced CO2 storage capacity. The goal was to accelerate the kinetics of rock-fluid reactions during the carbonation process. The starting rock material and the ball-milled samples were characterized using a variety of methodologies. The experimental results imply that only a few hours of wet ball milling with ethanol as process control agent can substantially increase the CO2 storage capacity of pyroxenites. Through temperature-programmed desorption of CO2 (CO2-TPD) experiments, we show that the optimum milling conditions are 4 h of ball milling with 50 wt% ethanol, leading to an increase of the CO2 uptake of the studied rock material by 41 times. This notable increase designates that pyroxenites are very promising lithologies for CO2 storage via ex situ carbonation, and that ball milling can be an effective preparation technique for this process, providing an efficient and secure carbon storage solution. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd.