Research has shown that soils containing crushed concrete, brick demolition and basic igneous rocks can remove substantial amounts of CO2 from the atmosphere through the formation of soil carbonates. This is an innovative technique of extracting CO2 from atmosphere which takes into account both climate change on waste management.
The formation of soil carbonates, which are predominately composed of CaCO3, depends on two main factors: (i) the availability of calcium; and (ii) carbonate in solution. Calcium is naturally derived from the weathering of silicate minerals (plagioclase feldspars, pyroxenes etc.) that commonly occur in basic igneous rocks (for example basalts and dolerites), or from artificial calcium silicate and hydroxide minerals within concrete and cement.
Carbonate carbon is mainly derived ultimately from photosynthesis, based on stable isotope studies.
During the process, silicate minerals, in particular calcium silicates, react with dissolved CO2 to form carbonates. This leads to the removal of atmospheric CO2 and its subsequent storage in a stable, inorganic state. Once formed within the substrate, this is a permanent store for CO2.
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