Green photocatalytic remediation of Fenthion using composites with natural red clay and non-toxic metal oxides with visible light irradiation. Issue 1 (2nd January 2023)

• Record Type: Journal Article
• Authors: Santos, Leila Maria Mendes; Nascimento, Madson M.; Borges, Sheila dos Santos; Bomfim, Elton; Macedo, Victória de Jesus; Silva, Luciana Almeida
• Is Part Of: Environmental technology. Volume 44:Issue 1(2023)
• Page Start: 118
• Page End: 129
• Publication Date: 2023-01-02
• Subjects: Photocatalysis -- pesticide -- Fenthion -- red clay -- sunlight; Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2021.1964611
• Languages: English
• ISSNs: 0959-3330

Abstract

ABSTRACT: In the present work, composites with non-toxic metal oxides, such as TiO2 and ZnO, and a natural red clay ( taua ) reach in hematite were used in the photocatalytic degradation of Fenthion. The composite TiO2 /Taua (0.5:1 wt. ratio) and pure TiO2 were prepared by sol-gel method while ZnO/Taua (0.5:1 wt. ratio) and pure ZnO were prepared by Pechini method. The materials were characterized by XRD, SEM, EDX, and DRS. The anatase phase was formed in both pure TiO2 and TiO2 /Taua, while the hexagonal phase was formed in pure ZnO and ZnO/Taua. The bandgap energies for the two composites were narrowed compared to the respective pure oxides as consequence of the hematite (α-Fe2 O3, E g = 2.1 eV) in the red clay, reaching 2.1 eV for TiO2 /Taua and 2.0 eV for ZnO/Taua, while the bandgap energies for pure TiO2 and ZnO were 3.2 and 3.0 eV, respectively. Fenthion was not degraded in the dark, but the concentration droped 20% after 180 min under visible light irradiation without photocatalyst and 60% after 210 min in the presence of the pure red clay. Both TiO2 /Taua and ZnO/Taua composites were also photocatalytic active to degrade Fenthion ( λ > 420 nm), with degradation of 78% (in 180 min) and 85% (in 210 min) respectively. In the optimized conditions (pH 2, 100 mg L −1 of H2 O2 and 30 mg L −1 of Fenthion), the ZnO/Taua composite was the most efficient, reaching 89% degradation in up to 30 min, with Fenthion sulfoxide as the degradation product. GRAPHICAL ABSTRACT: UF0001