Comparative Study of Zn Loading on Advanced Functional Zeolite NaY from Bagasse Ash and Rice Husk Ash for Sustainable CO2 Adsorption with ANOVA and Factorial Design

The Diffusion Behavior of CO2 Adsorption from a CO2/N2 Gas Mixture on Zeolite 5A in a Fixed-Bed Column

The objective of this research was to investigate the behavior and conditions for CO2 adsorption using a mixture of CO2/N2 over a fixed-bed column of zeolite 5A. The study was performed with a variation in gas composition of CO2/N2 as a 20/80, 50/50, and 80/20 volume %, the adsorption temperatures as 298, 333, and 373 K and the total feed flow rates as 1, 2, and 4 L/h under 100 kPa pressure. The Bohart–Adams, Yoon–Nelson, and Thomas models were used to predict the breakthrough behavior of CO2 adsorption in a fixed column. Furthermore, the adsorption mechanism has been investigated using the kinetics adsorption of pseudo-first-order, pseudo-second-order, Boyd model, and intraparticle model. Increasing the CO2 composition of a gas mixture resulted in a high CO2 adsorption capacity because of the high partial pressure of CO2. The capacity of CO2 adsorption was decreased with increasing temperature because of physical adsorption with an exothermic reaction. The CO2 adsorption capacity was also decreased with increasing feed flow rates with inadequate time for CO2 adsorbates diffusion into the pores of the adsorbent before exiting the packed bed. The CO2 adsorption by zeolite 5A confirmed that the physical adsorption with intraparticle diffusion was the rate-controlling step of the whole process.

CO2 adsorption performance of template free zeolite A and X synthesized from rice husk ash as silicon source

In this work, zeolite NaA (RA) and NaX (RX) have been successfully synthesized using rice husk ash and it is a low cost synthesis process and it does not produce environmental hazards. Sodium silicate (SS) is extracted from rice husk ash which is an alternative silica source for zeolite synthesis. The zeolites are prepared by using a SS silica source extracted from the rice husk ash, and it has been used as an adsorbent for the CO₂ adsorption process which may help in controlling the global warming problems. The zeolites are synthesized by a hydrothermal method without using any organic templating agent. FESEM and TEM micrographs revealed that the synthesized zeolites RA and RX have “Ice cube” and octahedral morphology respectively. From the N₂ sorption studies, the BET surface area of the synthesized zeolites have been found and are 106.25 m² g⁻¹ and 512.79 m² g⁻¹ respectively. The maximum CO₂ adsorption capacities of zeolite RA and RX are 2.22 and 2.45 mmol g⁻¹, respectively at a temperature of 297.15 K. The recorded data are fitted by using non-linear adsorption isotherm models of Langmuir, Freundlich and Toth isotherm models. The fitted isotherm models are observed to be a type I adsorption isotherm according to the IUPAC classification criterion.

In this work, zeolite NaA (RA) and NaX (RX) have been successfully synthesized using rice husk ash as source and it is a low cost synthesis process and it does not produce any environmental hazards.