Amine modification on kaolinites to enhance CO2 adsorption

•CO2 adsorption of kaolinite can be enhanced through amine modification.•CO2 adsorption increases with an increase in amine loading.•The highest CO2 adsorption capacity is 149.0 mg-CO2/g-sorbent.•CO2 adsorption is thought to occur through chemical adsorption.•Kaolinite has important advantages as an adsorbent.

The objective of our study was to prepare an effective and low-cost adsorbent for CO2 capture and to provide detailed analyses of adsorption-related properties. For this purpose, we treat the naturally abundant kaolinite with amines using the wet impregnation method. The thermogravimetric analysis indicates that the CO2 adsorption capacity of kaolinite (3.3 mg/g) can be enhanced through amine modification and increases with an increase in amine loading. In terms of amine-modified parameters, it is observed that kaolinite modified with 4MEA + 1EDA with 50 wt% has the best CO2 adsorption capacity (149.0 mg/g). We also speculate, based on X-ray diffraction and Fourier transformation infrared spectroscopy results, that CO2 adsorption onto amine-modified kaolinite occurs through chemical adsorption. This further substantiates the conclusion that the inexpensive and commonly available kaolinite is a potential solid carrier and is also a good adsorbent for CO2 capture with amine modification.

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