Inorganic nanotubes with permanent wall polarization as dual photo-reactors for wastewater treatment with simultaneous fuel production. Issue 9 (25th July 2021)

• Record Type: Journal Article
• Authors: Patra, Sabyasachi; Schaming, Delphine; Picot, Pierre; Pignié, Marie-Claire; Brubach, Jean-Blaise; Sicard, Lorette; Le Caër, Sophie; Thill, Antoine
• Is Part Of: Environmental science. Volume 8:Issue 9(2021)
• Page Start: 2523
• Page End: 2541
• Publication Date: 2021-07-25
• Subjects: Environmental sciences -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d1en00405k
• Languages: English
• ISSNs: 2051-8153

Abstract

Abstract : Janus methyl imogolite nanotube (Imo-CH3 ) with a hydrophobic internal cavity and a hydrophilic external surface, and possessing a permanently polarized thin wall, has been shown to act as a dual photo-reactor for wastewater treatment with simultaneous fuel production. Abstract : Photocatalytic production of fuels, even in small quantities, from the mineralization of hazardous pollutants, is a promising and renewable way of recycling wastewater. In the present work, the potential of methyl functionalized inorganic aluminosilicate nanotubes (methyl imogolite/Imo-CH3 ) as photocatalytic nanoreactors for this application is demonstrated. Using the phototoxic polycyclic aromatic hydrocarbon dibenzo( a, h )anthracene (DBAN) as a model pollutant, we show that DBAN molecules can be efficiently trapped inside Imo-CH3 nanotubes in an aqueous medium to undergo subsequent oxidative photo-degradation under UV light. The kinetics of this photo-degradation were shown to depend strongly on both the initial DBAN concentration in the nanotubes and the presence/absence of dissolved dioxygen. The photo-degradation process followed a complex mechanistic pathway, consisting of combined photo-oxidation and photo-cycloaddition reactions, where detection of carbon dioxide (CO2 ) as a photo-oxidation product confirmed the mineralization of encapsulated DBAN. CO and CH4 molecules were also formed, however these could arise from the further photo-reduction of CO2 on the external surface of the nanotubes. Moreover, dihydrogen (H2 ) was produced upon UV illumination under anaerobic conditions due to water reduction reactions on the external surfaces of Imo-CH3 nanotubes. The possible mechanistic pathways of these processes are proposed, and the dual capability of Imo-CH3 nanotubes for simultaneous pollutant degradation and H2 production is then demonstrated – a rare feat for a single photocatalyst material.