(139b) Carbon Dioxide Capture and Utilization Technology for Recycling Heavy Metals from Industrial Metal Wastes

Uncontrolled release of anthropogenic CO₂ emissions from power plants and other industries (e.g., cement, steel production, natural gas production, etc.) is causing an alarming situation, like global climate change. Due to global warming, an increase in sea level of 38 cm and 1.9 ℃ in global mean temperature has been predicted by the year 2100. Scientists are trying to develop efficient and cost-effective carbon capture and sequestration technologies to combat these climate changes. Although carbon capture and storage (CCS) is the conventional method presently used, the processes of transportation of CO₂ to the storage site, injection of CO₂ in the rock pores, and storage depends on complicated machinery and suitable underground reservoirs. In addition, the process poses the risk of accidental release of CO₂ due to seepage. Carbon capture and utilization (CCU) is currently the preferred option as it can mitigate global climate change by converting the captured CO₂ into value-added chemicals such as chemicals and fuels at the same time. The present work aims to develop disruptive technology for capturing and utilizing carbon dioxide to recycle heavy metals (e.g., copper, zinc, nickel, cobalt, etc.). The added advantage of our current technology lies in reducing the carbon footprint from mining and utilizing other secondary sources of metals like e-wastes and other industrial wastes. E-waste (e.g., PCBs, copper wires, etc.) is also referred to as urban mines as it is a rich source of many valuable metals. Unplanned discard of these hazardous wastes has a negative impact on the environment as well as human health. The objective of the present work is to recycle e-wastes and other hazardous industrial wastes using carbon dioxide from flue gas and extract the valuable metals in metal carbonate, a stable form of metal salts. About 97% zinc extraction has been achieved in the present work from an industrial zinc waste, utilizing captured CO₂ using ammonia solution in a scrubber. Zinc has been extracted as zinc carbonate, having numerous industrial applications, like catalyst synthesis, rubber production, personal cleanliness products, petroleum industry as a sulfur absorber, and feed additives for animals.