Calcium hydroxide composition and carbon removal in air using the same

A process for direct capture of carbon dioxide in air, the process comprising:

• providing a calcium hydroxide-based composition;
• contacting said composition with air so as to capture CO2 contained in said air by transforming at least some of the calcium hydroxide of said composition into calcium carbonate, forming a calcium carbonate-based composition;
• collecting the calcium carbonate-based composition;
• extracting at least some CO2 from at least some of the collected calcium carbonate-based composition;
• wherein said calcium hydroxide-based composition comprises Ca(OH)2 and an ionic compound with a content of 0.05% or higher than 0.05% by weight relative to the content of Ca(OH)2 but less than 10.0% by weight relative to the content of Ca(OH)2, said ionic compound comprising an alkali metal cation, wherein the calcium hydroxide-based composition has a weight fraction of Ca(OH)2 of at least 80% on a dry basis.