Enhancing the rate of ex situ mineral carbonation in dunites via ball milling

• Dunitic materials with enhanced CO2 uptake were created via ball milling (BM).
• The optimum conditions are 12 h of BM with 50 wt% ethanol as process control agent.
• The BM process increased the CO2 uptake of dunites by a factor of 6.9.
• The presence of H2O has a substantial positive effect on CO2 uptake.
• The positive effect of H2O on CO2 uptake is more evident after the BM process.

The investigation of potential options for CO2 sequestration is of vital importance for alleviating the ongoing climate problem. This paper presents an efficient method for enhancing the ex situ carbonation of dunites. The ball milling process was applied to a dunite from the Troodos ophiolite (Cyprus), in order to create a new type of material with enhanced CO2 uptake. Through CO2 chemisorption followed by temperature-programmed desorption (CO2-TPD) experiments, optimum ball milling conditions were found (12 h of wet ball milling with 50 wt% ethanol as process control agent), leading to an increase of CO2 uptake of dunite by a factor of 6.9. A further increase of CO2 uptake by 10% was accomplished after 4 h of additional ball milling with smaller balls. Additionally, CO2-TPD along with in situ DRIFTS studies indicated that the CO2 uptake of the dunitic materials can be substantially enhanced by the presence of H2O during CO2 chemisorption. The positive effect of H2O on CO2 chemisorption becomes much more evident after the ball milling process. Specifically, the CO2 uptake of the ball-milled sample (BM45) was enhanced by a factor of 5.8 (from 181.9 to 1047.5 μmol g−1), when CO2 chemisorption was performed in the presence of 20 vol% H2O.

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