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. 2023 May 25;24(11):9281.
doi: 10.3390/ijms24119281.

Faujasite-Type Zeolite Obtained from Ecuadorian Clay as a Support of ZnTiO3/TiO2 NPs for Cyanide Removal in Aqueous Solutions

Ximena Jaramillo-Fierro  1 , Hipatia Alvarado  2 , Fernando Montesdeoca  2 , Eduardo Valarezo  1
Affiliations

Faujasite-Type Zeolite Obtained from Ecuadorian Clay as a Support of ZnTiO3/TiO2 NPs for Cyanide Removal in Aqueous Solutions

Ximena Jaramillo-Fierro et al. Int J Mol Sci. .

Abstract

In this study, zeolites prepared by the hydrothermal method from Ecuadorian clay were combined with the precursor clay and with the semiconductor ZnTiO3/TiO2 prepared by the sol-gel method to adsorb and photodegrade cyanide species from aqueous solutions. These compounds were characterized by X-ray powder diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive X-rays, point of zero charge, and specific surface area. The adsorption characteristics of the compounds were measured using batch adsorption experiments as a function of pH, initial concentration, temperature, and contact time. The Langmuir isotherm model and the pseudo-second-order model fit the adsorption process better. The equilibrium state in the reaction systems at pH = 7 was reached around 130 and 60 min in the adsorption and photodegradation experiments, respectively. The maximum cyanide adsorption value (73.37 mg g-1) was obtained with the ZC compound (zeolite + clay), and the maximum cyanide photodegradation capacity (90.7%) under UV light was obtained with the TC compound (ZnTiO3/TiO2 + clay). Finally, the reuse of the compounds in five consecutive treatment cycles was determined. The results reflect that the compounds synthesized and adapted to the extruded form could potentially be used for the removal of cyanide from wastewater.

Keywords: ZnTiO3/TiO2; adsorption; clay; cyanide; faujasite; nanoparticles; photocatalysis.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
X-ray diffraction (XRD) pattern of TZC composite, clay, zeolite, and ZnTiO3/TiO2. M: montmorillonite, L: albite, C: cristobalite, Q: quartz, H: heulandite, E: hematite, F: FAU zeolite, A: LTA zeolite, P: Na-P1 zeolite, An: TiO2, and T: ZnTiO3.
Figure 2
Figure 2
Scanning electron microscopy (SEM) images of (a) clay, (b) zeolite, (c) ZnTiO3/TiO2, and (d) TZC composite.
Figure 2
Figure 2
Scanning electron microscopy (SEM) images of (a) clay, (b) zeolite, (c) ZnTiO3/TiO2, and (d) TZC composite.
Figure 2
Figure 2
Scanning electron microscopy (SEM) images of (a) clay, (b) zeolite, (c) ZnTiO3/TiO2, and (d) TZC composite.
Figure 3
Figure 3
Energy-dispersive X-ray (EDX) spectra of (a) clay, (b) zeolite, (c) ZnTiO3/TiO2, and (d) TZC composite.
Figure 3
Figure 3
Energy-dispersive X-ray (EDX) spectra of (a) clay, (b) zeolite, (c) ZnTiO3/TiO2, and (d) TZC composite.
Figure 4
Figure 4
Percentage of adsorption of cyanide species on the powdered and extruded compounds. (Adsorbent = 200 mg L−1, KCN = 20 mg L−1, pH = 7.0 ± 0.1).
Figure 5
Figure 5
Effect of pH on the adsorption of cyanide species on extruded compounds. (Adsorbent = 200 mg L−1, KCN = 20 mg L−1, pH = 3–11).
Figure 6
Figure 6
Absorption isotherms of the extruded compounds (a) C, (b) TC, (c) ZC, and (d) TZC. (Adsorbent = 200 mg L−1, KCN = 5–200 mg L−1, pH = 7.0 ± 0.1).
Figure 7
Figure 7
Thermodynamic study of cyanide adsorption on extruded compounds. (Adsorbent = 200 mg L−1, KCN = 20 mg L−1, pH = 7.0 ± 0.1).
Figure 8
Figure 8
Adsorption kinetics of extruded compounds (a) C, (b) TC, (c) ZC, and (d) TZC. (Adsorbent = 200 mg L−1, KCN = 20 mg L−1, pH = 7.0 ± 0.1).
Figure 9
Figure 9
Intraparticle diffusion plots for cyanide removal by extruded compounds. (Adsorbent = 200 mg L−1, KCN = 20 mg L−1, pH = 7.0 ± 0.1).
Figure 10
Figure 10
Photocatalytic cyanide degradation by the extruded compounds. (Catalyst = 200 mg L−1, KCN = 20 mg L−1, pH = 7.0 ± 0.1, λ = 310 nm).
Figure 11
Figure 11
Percentage of cyanide adsorbed and photodegrade by the extruded compounds.
Figure 12
Figure 12
Extruded compounds reuse experiment.
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