In our present time, the significant variation of weather conditions known as climate change has become more evident than ever. This long-term shift in temperature is attributed to global warming, caused by increased concentrations of greenhouse gases in the Earth's atmosphere.
Among all the types of greenhouse gases, carbon dioxide is of particular concern to scientists since it is emitted from human activities like energy combustion and industrial processes. As a solution to increasing the amount of CO2 in the atmosphere, carbon capture and storage (CCS) technology is developed to help mitigate emissions.
Synthesis of 2D Mica Nanosheets
Traditionally, liquid adsorbents are used in capturing and storing CO2 from ambient air, but they are prone to equipment corrosion, costly, and require a high amount of energy for regeneration. Solid porous materials are being explored for CO2 adsorption to overcome these challenges.
Mica, a cheap and naturally occurring mineral, has the potential to be used as a material for CO2 adsorption. This has been the focus of carbon capture research by Associate Professor Wu Ping of the Singapore University of Technology and Design (SUTD).
Mica is known to form alumina silicate layers which are connected through ionic bonds by interlayer potassium cations. However, the complex sheet-like structure makes separating this mineral into a few layers difficult to form two-dimensional (2D) nanosheets ideal for CO2 capture—attempts to do this require long reaction times and high energy requirements.
To develop an efficient approach to producing 2D mica nanosheets, Prof. Wu and his SUTD team collaborated with scientists from the Agency for Science, Technology, and Research, where they combined microwave chemistry and solvothermal mechanochemistry. The team harnessed the energy from microwaves and solvothermal methods to synthesize exfoliated mica (eMica) nanosheets. Unlike bulk mica, eMica nanosheets are more uniform in lateral size and thickness.
Upon testing the potential of eMica for CO2 capture, the research team found that its adsorption capacity was 87% higher than its bulk form. The eMica nanosheets even surpassed the other clay minerals modified for this purpose.
According to Prof. Wu, the superior capacity of eMica nanosheets to adsorb CO2 is attributed to its high specific surface area and the pores in its expanded layers. Adsorbing CO2 can also be improved by adding potassium carbonate (K2CO3) deposits on the eMica nanosheets.
How Does Carbon Capture and Storage Work?
Carbon capture and storage refers to various technology utilized to fight climate change by reducing the emitted carbon dioxide in the atmosphere. The idea behind this concept is to capture the generated CO2 from burning fossil fuels before it is released into the atmosphere.
Carbon capture takes place in large stationary sources of CO2, such as industrial plants that manufacture chemicals. Liquid substances remove the CO2 before it goes out of the smokestack. The captured CO2 is compressed to convert into liquid to transport it to storage sites.
Due to the success of this technology in industrial plants, there has become considerable interest in using this method to remove CO2 from the atmosphere. One of the available options is bioenergy, where CO2 is removed from the air through photosynthesis. Another approach s by direct air capture (DAC), where CO2 is captured from the atmosphere using a chemical process.
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