Formation of porous calcite mesocrystals from CO2–H2O–Ca(OH)2 slurry in the presence of common domestic drinks

Abstract

This study reports a simple, innovative and fast method to synthesize porous calcite mesocrystals with high specific surface area from Ca(OH)₂–water–CO₂ slurry in the presence of common domestic drinks (soluble coffee, orange juice, carrot juice, white wine, sugar–water and milk). As already reported in previous studies, calcite nanoparticles (<100 nm) can be obtained at low temperature (≤30 °C) in the absence of additives. We demonstrate herein that the use of common domestic drinks as additives can induce the formation of calcite mesocrystals with a peanut-like morphology, i.e. the formation of a nanostructured material in which the constituent calcite nanoparticles (10 < size < 50 nm) are aligned and/or oriented, forming regular micrometric (<3 μm) 3D porous aggregates. We note that the additives used in the system did not induce polymorphism because only calcite was measured/observed in the solid products using XRD, FESEM and TEM or in collected-time suspensions using Raman spectroscopy. This innovative method for synthesizing porous calcite mesocrystals has significant relevance because only a few hours (6 h < time < 24 h) were required and synthesis was possible using a dispersed triphasic gas–liquid–solid system under high non-constant CO₂ pressure (anisobaric conditions), contrary to available methods requiring days or weeks, in which reactant diffusion is typically imposed since these systems were initially designed to mimic biomineralization processes. Moreover, this new synthesis method could easily be scaled to industrial processes to produce calcite mesocrystals with high specific surface area (up to 30 m² g⁻¹). The nanostructured state, the mesoporosity and the high specific surface area for these synthesized calcite mesocrystals could improve the typical industrial and medical uses for synthetic calcite.