Adsorption of CO₂ Using “Sugar Cube”-Shaped Zeolite A Type Derived from Thermally Treated Kaolin and NaOH

Abstract

Making use of low-cost zeolite adsorbents for CO2 adsorption is an encouraging technique for the adsorption of the CO2 gas emitted from flue gases. In the present work, the zeolites were successfully synthesized from kaolin by the conversion of metakaolin and also by using 2.5 and 3 M of NaOH. The transformation of kaolin into metakaolin was achieved through a thermal treating process for 4 h at various temperatures such as 600, 700, 800, and 900 °C. The molar ratio used for the synthesis was X Na2O:Al2O3:1.926 SiO2:128 H2O (where X = 2.5 and 3 M of NaOH). The 2.5 and 3 A (600–900 °C) zeolite was synthesized through the hydrothermal process without using any organic template agent. The “sugar cube” and octahedral-shaped morphology are observed through FESEM and TEM analysis. The textural properties of the synthesized samples were found using N2 adsorption/desorption studies. The type IV and type I adsorptions were identified from the sorption studies. However, the CO2 sorption studies are recorded at 297.15 K, and the type I adsorption isotherms were observed according to the IUPAC classification criterion. The experimentally observed data were fitted by nonlinear regression curve fit using a Langmuir, Freundlich, and Toth adsorption isotherm, and their parameters were recorded.