Synthesis of CaCO3–SiO2 composite using CO2 for fire retardant

Abstract

Calcium carbonate (CaCO3) and calcium silicate (Ca2SiO4) are widely used fillers for fire retardant to polymer and other materials. In recent years, reducing greenhouse gas has become a key issue for environmental concern. Capturing CO2 gas as a solid form in room temperature and ambient condition is attractive method to reduce the greenhouse gas and uses as a fire retardant, such as CaCO3–SiO2 composite. Calcium carbonate–silica composite (CaCO3–SiO2) has been synthesized by bubbling CO2 gas into an aqueous Ca(OH)2 medium with NH4OH catalyst. Completely dissolved and transparent Ca(OH)2 solution was prepared to react Ca(OH)2, tetraethoxy orthosilicate (TEOS), and CO2. The characteristic FTIR absorption peaks of CaCO3 and SiO2 appeared at 1450, 1100, 875 and 712 cm−1. Field emission scanning electron microscope (FESEM) images show mixed particle sizes with small particles (approximately several hundred nanometers) and large particles (approximately several micrometers). Using completely dissolved Ca(OH)2 and TEOS with NH4OH catalyst is one of the effective method not only capturing CO2 greenhouse gas and use as fire retardant.