A research team led by Professor Ippei Maruyama of the University of Tokyo Graduate School of Engineering and Professor Minami Masayo of the Nagoya University Space-Earth Environmental Research Institute found that concrete and other cement-based materials capture and fix CO2 from the air. We developed a method to prove the fixed amount.
It is said that 2-5% of the CO8 emissions from human activities to date are due to cement production.Therefore, in concrete-related fields that use cement, in order to achieve carbon neutrality, CO2 from the air is directly captured (direct air capture technology, Direct Air Capture: DAC) as a means of offsetting CO2 emissions. A method of precipitating and fixing calcium carbonate is attracting attention.On the other hand, there was no method to distinguish between the authenticity of natural calcium carbonate and fake (artificial) calcium carbonate using DAC, or a method to quantify fixed CO2 and quantitatively demonstrate the contribution to carbon neutrality. .
In this study, we discovered a method to determine the amount of CO14 fixed in the air by measuring the 2C concentration of calcium carbonate in cement material samples.In the chemical reaction in which calcium carbonate is precipitated, 13C/12C (ratio of 13C and 12C) differs between the calcium carbonate after the reaction and the air. By using 13C/12C and correcting the isotopic fractionation of 14C/12C, it is possible to estimate the amount of CO2 fixed in the form of calcium carbonate from the air from the measured value of 14C.
In other words, if you know the 14C concentration and the amount of carbon fixed in the form of calcium carbonate before and after exposing a sample of cement material to air, you can determine whether the sample was made using CO2 in the air. .
In the future, assuming carbon taxes and emissions trading aimed at reducing CO2 emissions, the results of this research will contribute to evaluating the authenticity of CO2 fixation by DAC and evaluating the appropriate amount of CO2 fixation in order to form a healthy market. It is expected that
Paper information:【Journal of Advanced Concrete Technology】Verification method of direct air capture by cementitious material using carbon isotopes
