Langmuir-Hinshelwood-Hougen-Watson Heterogeneous Kinetics Model for the Description of Fe (II) Ion Exchange on Na-X Zeolite

Abstract

This study aimed to investigate the kinetics of the anion exchange step of ferrous ions with Na-X zeolite in a temperature range of 20 and 80°C for a period of up to 8 hours. A ferrous sulfate heptahydrate solution was used as a ferrous ion source to exchange with the sodium of the Na-X zeolite. The results showed a change in the physical appearance of the zeolite with the progress of the ion exchange process. The catalyst color was observed with the progress of the ion exchange time and changed from yellow to brown. The ferrous ion exchanged contents increased with temperature and reached 0.519 at 80°C after 8 hours. A kinetic model based on the Langmuir-Hinshelwood-Hougen-Watson model was suggested and developed to describe the ion-exchange process. The proposed model was solved numerically, and the results indicated its ability to describe the experimental results with high correlation coefficients. Finally, the activation energy for the forward reaction was 31590.7J/mole compared to 28105.5J/mole for the backward, and the frequency factors for the forward and backward reactions were investigated.

Textural Properties Characterization for NaX and FeX Zeolites by Nitrogen Adsorption-desorption Technique

“…The present NaX has a Vp value of 0.34901 cm 3 /g, greater than the previous work for the NaX [30] and zeolite Y [44]. The current FeX Vp (0.2768 cm 3 /g) was in the same range as the obtained Fe exchange [44][45][46].…”

“…The ion-exchange process appears to impact characteristics such as surface area and pore volume significantly. Textural parameters were compared and summarized in Table 2 for zeolite and FeX, as well as various properties for mesoporous with the same porous structure described in earlier studies [30,[44][45][46]. The surface area of the current NaX was 569.14 m 2 /g, which was comparable to NaX [30,[44][45][46].…”

“…Textural parameters were compared and summarized in Table 2 for zeolite and FeX, as well as various properties for mesoporous with the same porous structure described in earlier studies [30,[44][45][46]. The surface area of the current NaX was 569.14 m 2 /g, which was comparable to NaX [30,[44][45][46]. However, the surface area of the present FeX was 213.31 m 2 /g, which was similar to the surface area of the Fe-zeolite obtained [44] and lower than the stated surface area of Fe2O3-13X [46].…”

Synthesis, Characterizations, and Recent Applications of the Silica-based Mobil Composition of Mesoporous Material: A Review

“…Zeolites have pores that are smaller than 2 nm in diameter, which improves many industrial reactions by increasing the surface area, but the pores are too small to hold a wide range of larger molecules. Diffusion restrictions brought on by smaller pores also have an impact on how well zeolite systems work in various applications [17][18][19][20][21][22][23][24][25][26][27][28][29].…”