From Waste to Value: Conversion of Calcium Sulfate to Vaterite via Carbon Capture and Storage

ABSTRACT Developing effective solutions to reduce carbon dioxide emissions into the atmosphere is crucial for mitigating climate change. While various methods for CO 2 capture and storage exist, many of the proposed approaches are not yet economically viable on larger scales. Here we introduce a new sustainable strategy for carbon management that relies on the carbonation of calcium sulfate, an abundant byproduct of various industrial processes. Through in‐situ observation tools, we uncover the carbonation mechanism and demonstrate that phase‐pure vaterite (a metastable form of calcium carbonate) can be obtained without additives via straightforward conversion of gypsum powder in water at ambient conditions. The resulting particles exhibit interesting properties such as high specific surface area and reactivity. To demonstrate the value of the products for real‐life applications, the obtained vaterite was tested as a raw material for construction. Upon mixing with water, the spherical vaterite particles transformed into aragonite crystals through a dissolution‐reprecipitation pathway, which was accompanied by rapid compressive strength development on a level comparable to that of conventional cements. Our findings constitute an important first step toward repurposing gypsum waste as a sink for carbon dioxide and source to produce materials with reduced environmental impact.