Photocatalytic degradation of methyl blue by silver ion-doped titania: Identification of degradation products by GC-MS and IC analysis

Abstract

An anionic triphenyl methane dye, methyl blue ((disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate) was degraded photocatalytically with undoped micro-TiO2- and Ag(+)-doped micro TiO2 in a slurry-type batch reactor under UV irradiation and the efficiency was compared with that obtained using nano-TiO2- and Ag(+)-doped nano-TiO2. The influence of different parameters, i.e., photocatalyst loading, dye concentration, initial pH, temperature, depth of solution, interfering ions and electron acceptors on the dye degradation was investigated. The decolorization and mineralization efficiency was better for Ag(+)-doped micro-TiO2 than undoped micro-TiO2. Nano-TiO2 was more efficient than micro-TiO2, while Ag(+)-doped nano-TiO2 was the most efficient of all. Cost analysis showed degradation using micro-TiO2- and Ag(+)-doped micro-TiO2 are much cheaper than that using nano-TiO2 and Ag(+)-doped nano-TiO2. Therefore Ag(+)-doped micro-TiO2 was used for the detailed study. The degradation products formed were identified using GC-MS analysis after photocatalytic degradation for 180 min with Ag(+) -doped micro TiO2. Ion chromatography analysis was carried out for anions to identify the end products of degradation.

AgAu Nanotubes: Investigating the Effect of Surface Morphologies and Optical Properties over Applications in Catalysis and Photocatalysis

“…In all experiments, no organic degradation products were identified by gas chromatography mass spectrometry (GC-MS) analyses, which indicate the complete mineralization of methylene blue during the oxidation processes. 47,58,59 In fact, as expected, a progressive increase in the methylene blue conversion was observed when stronger oxidizing agents were employed. More specifically, the conversion of methylene blue using both AgAu nanotubes as function of the oxidizing agent increased in the following order: atmospheric air (Figures 6A-6B) < hydrogen peroxide ( Figures 6C-6D) < tert-butyl hydroperoxide ( Figures 6E-6F).…”

Ag modified ZnS for photocatalytic water pollutants degradation: Influence of metal loading and preparation method

“…On the other hand, the decrease of photocatalytic activity, observed at higher Ag content (0.5Ag), can be explained considering that Ag particles may act as a recombination center due to the increase of Ag particle size on ZnS surface (as argued from the reduction of specific surface area) [67]. This effect probably determined the worsening of the photocatalytic activity, as also observed in the literature [68]. The total inhibition of photocatalytic activity, observed for 2Ag and 4Ag, could also be explained considering the very low optical band-gap value of these samples (2.1 eV for 2Ag and 1.8 eV for 4Ag), which brings to the inhibition of MB photodegradation process because of the possible more facile electron/hole recombination in the excited state of the catalyst [21].…”

Solar Based Photocatalytic Decolorization of Four Commercial Reactive Dyes Utilizing Bound TiO₂-Fe₃O₄ Nanocomposite

“…As shown in Table 7, there were good linear [38][39][40]44,[51][52]. It is assumed that no intermediate products present or strongly absorbed than the dye on the surface of the photocatalyst [38,40].…”