Nickel Nanoparticles for Carbon Capture via Micro CO₂ Bubbles

To capture anthropogenic carbon dioxide (CO₂), monoethanolamine (MEA) has been dominantly used due to its low cost and excellent efficiency. One limitation of this approach is the generation of wastewater containing a heavy chemical harmful to the environment. Another barrier is that MEA is effective only in a basic condition while the capturing solution becomes acidic indispensably as excessive CO₂ is hydrated. In our previous study, we found that nickel (Ni) nanoparticles (NPs) catalyze the CO₂ hydration dramatically regardless of pH conditions. This work uses Ni NPs as a possible alternative to MEA for carbon capture. To evaluate NiNPs’ performance for CO₂ capturing, a bubble-based microfluidic approach is employed in a long serpentine microchannel. In a large parameter space, time-dependent changes in size along the microchannel are monitored at high-speed until CO₂ dissolution reaches equilibrium to quantify CO₂ dissolution. We found that the rate and total amount of CO₂ dissolution with NiNPs are superior to those with MEA. This study proves that NiNPs alleviate environmental concerns raised by MEA and therefore could be a good catalyst for carbon capture. The fundamentals and governing physics of enhanced CO₂ dissolution in NiNPs-water mixture will be also discussed.