Abstract
For promoting the absorption of atmospheric CO2 into the ocean, the use of electrolysis treatment of seawater to produce calcium carbonate (CaCO3) and decrease the concentration of carbonate ion in a superficial seawater was studied. Through an experiment using a continuous flow electrolytic cell with a porous separating membrane, a large amount of H2 gas and CaCO3 particle were produced at the cathode, and a small amount of O2 gas was produced at the anode. CO2 gas was not entirely emitted during the electrolysis treatment, and the mixture of catholyte seawater, after the separation of CaCO3, and anolyte seawater was alkalined at pH 8.3-8.7 compared to the raw seawater of pH 8.1. A precipitate produced by the electrolysis treatment was composed of aragonite-CaCO3 and brucite-Mg(OH)2, and the amount, chemical composition and crystal shape were changed by the electrolysis conditions. Based on the fact that the excess atmospheric CO2 could be stably isolated from the biosphere as solid CaCO3 submerged on a sea floor, and alkalined seawater should have a potential to promote the absorption of atmospheric CO2 without seawater acidification by the direct CO2 discharge, the proposed method might become a solution for global warming.
