A Comparative Study on The Adsorption Behavior of Congo Red on to ZnAl and ZnCr Layered Double Hydroxides

Abstract

In this work, two synthetic layered double hydroxides (LDH) consists of Zn2+ as M2+ cation with different M3+ cation, i.e., Al3+ and Cr3+ were used as an adsorbent for Congo Red removal aqueous solution. Both Zn-Al and Zn-Cr LDH were characterized by X-ray diffraction, FT-IR, and BET surface area analyzer. The effect of contact time, initial dye concentration, and temperature were evaluated in a batch technique in order to investigate the characteristic of Congo Red adsorption onto both adsorbents. The experimental data were assessed according to the parameter of adsorption kinetics, isotherm, and thermodynamics. The results of LDH characterization showed that Zn-Al LDH has a higher interlayer distance than Zn-Cr LDH, although Zn-Cr LDH has a higher surface area. The FT-IR analysis indicated the interlayer space of both Zn-Cr and Zn-Al LDH was dominated by CO32- as the interlayer anion species. The adsorption kinetics study of Congo Red on both LDH revealed that the adsorption process followed the pseudo-second-order model. For the adsorption isotherm, the experimental data fit well with the Freundlich model rather than the Langmuir model. The thermodynamic study indicated that the adsorption process that occurred on both adsorbents was spontaneous with exothermic nature.

Utilization of Rambutan Peel as s Potential Adsorbent for the Adsorption of Malachite Green, Procion Red, and Congo Red Dyes

“…The data presented in Figure 6 shows that there is an increase in the concentration of the adsorbed dye from 0 to 90 minutes, this indicates that the adsorbent has adsorbed the adsorbate due to the collision between the adsorbent and the adsorbate. The optimum time was then obtained at 90 minutes which was marked by a constant condition, where this condition occurred because the adsorbent was completely fi lled with adsorbate so that the adsorbent had reached the saturation point (Taher et al, 2020). The concentration of adsorbate can also aff ect the adsorption process as presented in Figure 6 shows that the greater the concentration of adsorbate, the amount of adsorbed substance also increases with time.…”