Reusability in visible light of titanate nanotubes for the removal of organic pollutants: role of calcination temperature. Issue 14 (20th June 2022)

• Record Type: Journal Article
• Authors: Ruiz-Castillo, Ana Laura; Hinojosa-Reyes, Mariana; Camposeco-Solis, Roberto; Ruiz, Facundo
• Is Part Of: Environmental technology. Volume 43:Issue 14(2022)
• Page Start: 2081
• Page End: 2098
• Publication Date: 2022-06-20
• Subjects: Titanate nanotubes -- calcination temperature -- adsorption -- photocatalysis -- visible light; Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2020.1866085
• Languages: English
• ISSNs: 0959-3330

Abstract

ABSTRACT: Titanate nanotubes (NTs) were synthesised by the hydrothermal method and later calcined at temperatures between 100–500°C. The calcined NTs were characterised and evaluated in the physicochemical adsorption of the safranin dye and photocatalytic degradation of caffeine. The materials calcined at low temperatures displayed a tubular structure and the H2 Ti3 O7 crystalline phase, which was transformed into anatase nanoparticles at 400°C. The NTs treated at 100°C showed the highest adsorption capacity (94%). Safranin was adsorbed through an ion-exchange mechanism, following the Langmuir isotherm and a pseudo-second-order kinetic model. While NTs calcined at lower temperatures were better for adsorption, the photocatalytic degradation of caffeine increased in samples calcined at higher temperatures with a maximum removal of 72%. The photocatalytic behaviour of the NT samples confirmed that the crystalline anatase structure in conjunction with structural OH groups enhanced the photocatalytic activity. The addition of isopropanol as a scavenger confirmed the important role played by the OH radicals in the photocatalytic process. NTs calcined at 300°C were efficient for both adsorption and photocatalytic processes. Due to its efficiency, this sample was reused after dye adsorption for the photocatalytic degradation of caffeine under visible light due to its enhanced absorbance in the visible region. This research work shows the potential of NTs for wastewater purification. GRAPHICAL ABSTRACT: UF0001