Carbon Storage through Rapid Conversion of Forsterite into Solid Oxalate Phases

Carbon capture and storage are likely to be critical components in lowering atmospheric CO₂ levels. Mineralization is often proposed as a method to store carbon and typically involves reacting CO₂ directly with silicate minerals, such as forsterite, to form carbonate minerals. However, this reaction is slow under standard conditions, so that sequestering significant amounts of carbon can take years or decades. Here, we demonstrate the feasibility of using a reaction between oxalic acid and forsterite to create stable carbon-bearing oxalate minerals. We performed a series of batch experiments at room temperature and pressure to quantify the forsterite dissolution rate and the efficiency of Mg utilization. Our results show that conversion of forsterite to Mg and Fe oxalate is achieved rapidly: after 30 days, 52% of Mg was converted to Mg oxalate so that 1 t of forsterite can be used to store 177 kg of carbon. Our calculations show that reacting ultramafic mine tailings with oxalic acid has the potential to make a significant contribution toward the global target for CO₂ removal by carbon capture and storage.