CO₂-induced multi-metal (Ca, Mg, Fe, Mn) precipitates and its interaction with CO₂

This study investigates the identification of multi-metal precipitate (MMP) synthesized by the co-precipitation of multi-metal cations (Ca²⁺, Mg²⁺, Fe²⁺_, and Mn²⁺) using NaOH in the atmospheric CO₂ and MMP-suspended solution with CO₂ of 1 bar at 25 °C for 2 h (CO₂-MMP) to evaluate the interaction with CO₂. The MMP was identified as a complex composite consisting of layered double hydroxide (LDH), metal hydroxide, metal oxides, and carbonates as minor. The CO₂-MMP shows the formation of carbonized minerals and dissolved LDH and Mg(OH)₂ due to reduced pH. The CO₂ uptake by CO₂-MMP is as much as ~ 0.029 mg/mg, indicating the involvement of Ca from both Mg-calcite/aragonite and CaFe-LDH in carbonation. Moreover, the CO₂ reaction improved the BET surface area of MMP by 150%, which indicates its potential for efficient CO₂ interaction. This study provides valuable insights into the precipitation of multi-metal cations and their interaction with CO₂.