Carbon dioxide fixation: Waste material utilization for under water applications

Increasing concentration of atmospheric green house gases such as carbon dioxide (CO
2
) that traps solar energy within the atmosphere are being investigated in connection with the warming of the planet and changes in climatic conditions. Carbon dioxide emitted from point sources plays major role for climate change. The steel industry is one of the largest energy consuming manufacturing sectors accounting for 3–5% of global carbon dioxide emissions. Mineral carbonation, involving the carbonation of the calcium and magnesium oxides in the steel slag fixes the carbon dioxide in the industrial waste. The process parametric studies are presented by varying the particle size, stirrer speed, temperature and pressures. The maximum carbonation efficiency obtained was in the range of 35-40% by direct carbonation method. Similarly results using catalysts such as acetic acid, ammonium chloride for the indirect carbonation method with carbon dioxide as well as flue gas are also presented. It is observed that the maximum carbonation efficiency is in the range of 85–97% with carbon dioxide and 50–55% with flue gases. The carbonated steel materials are proposed to utilize for the development of artificial reefs. Initial studies on the test blocks immersed in sea water are also discussed.