Method of capturing carbon dioxide using carbide slag

An method of manufacturing active carbide slag adsorbent for capturing carbon dioxide from a gaseous mixture at an ambient temperature, said method comprising

• obtaining carbide slag;
• regulating a water content of the carbide slag such that the water content of the carbide slag is approximately 10% to 40% of a dry mass of the carbide slag, and wherein, the step of regulating the water content of the carbide slag comprises heating the carbide slag at a temperature of about 105° C. and -contacting the active carbide slag adsorbent with the gaseous mixture containing carbon dioxide, thereby permitting the active carbide slag adsorbent to capture carbon dioxide.