Study of CO2 Capture Capability of Purified Carbide Lime Waste

During the production of acetylene, the CaO generated as a by-product quickly hydrates and forms a suspension of calcium hydroxide. This lime paste is not commonly used for building or industrial purposes, and it is usually stored in ponds as a waste, thus representing a problem for the manufacturer. The use of such a paste in the uptake of toxic or greenhouse gases such as SO₂ or CO₂ would therefore represent an alternative of significant value for its recycling. This requires however a pre-treatment of the waste to eliminate organic matter and sulphur that may limit the CO₂ adsorption capability of the lime. In most processes for CO₂ capture, the adsorbent solids are used repeatedly, so that the evolution of their characteristics during the cyclic regeneration are critical to determine the feasibility of their use in practical applications. Here we described the purification process of a lime paste from acetylene industry as well as the main characteristics of the resulting solid, together with the results of a cyclic study of its performance as CO₂ adsorbent.