Alternative Amine Scrubbing for CO2 Capture Utilizing Seawater and Nickel Nanoparticle Catalysts: A Microfluidic Approach

Abstract

As the consumption of fossil fuels has continuously grown to meet global energy demands, atmospheric emissions of greenhouse gases, particularly carbon dioxide (CO2), have rapidly increased over the last century. Excessive anthropogenic CO2 emissions have caused serious international concerns about climate change and its consequences. Postcombustion CO2 capture methods like amine scrubbing are currently being utilized to reduce CO2 emissions from fossil fuel power plants. Aqueous monoethanolamine (MEA) solutions are the most prominent solvents used in this process due to their high CO2 absorption capacity and rapid reaction rate. Unfortunately, the CO2 scrubbing process that employs the amine solutions produces environmentally harmful toxic wastewater and consumes large amounts of freshwater. This research analyzes the effectiveness of an alternative amine scrubbing method that utilizes seawater-based solutions containing nickel nanoparticles as catalysts. The goal is to minimize the use of MEA required in the amine scrubbing process and eliminate the use of freshwater. In a microfluidic environment, CO2 microbubbles were generated and their change in size with respect to time was observed to determine the CO2 absorption capacity and CO2 absorption rate of test solutions. Seawater demonstrated a greater intrinsic CO2 absorption capacity than freshwater, absorbing over 9% more CO2. Additionally, the energy required for solvent regeneration, the most energy intensive and costly part of amine scrubbing, was estimated to be 3-4% less in seawater. Moreover, seawater-based MEA solutions achieved up to 97% CO2 absorption, outperforming freshwater-based MEA solutions by approximately 10%. All seawater solutions demonstrated a faster CO2 absorption rate than their freshwater counterparts. Lastly, in seawater- and freshwater-based solutions, nickel nanoparticles were effective in improving CO2 absorption by up to 4% and 12%, respectively. Seawater- nickel nanoparticles-based amine solutions demonstrated the greatest capability for CO2 capture with the highest CO2 absorption capacity and CO2 absorption rate of all test solutions.