Counterion effect of cationic surfactants on the oxidative degradation of Alizarin Red-S photocatalysed by TiO2 in aqueous dispersion

Photocatalytic activity of G-TiO2@Fe3O4 with persulfate for degradation of alizarin red S under visible light

A composite photocatalyst combined with TiO₂, graphite (G) and Fe₃O₄ was prepared by co-precipitation method. Then the G-TiO₂@Fe₃O₄ was employed with persulfate (PS) to degrade alizarin red S (ARS) under visible light. The removal rate of ARS reached 100% after 60 min irradiation. The degradation rate constant of G-TiO₂@Fe₃O₄/PS exhibited 20.8, 9.0 and 3.1 times than that of TiO₂, G-TiO₂ and G-TiO₂@Fe₃O₄, respectively. The effects of photocatalyst dosage, mass ratios of graphite and Fe₃O₄ to TiO₂, PS dosage, initial pH and ARS concentration on the degradation efficiency were investigated. The optimal removal efficiency of ARS was obtained when G-TiO₂@Fe₃O₄ dosage was 0.25 g/L, G: TiO₂ = 0.005, Fe₃O₄: TiO₂ = 0.8, PS concentration was 6 mmol/L, initial pH = 3, and initial concentration of ARS was 100 mg/L. The SO₄·^- was demonstrated more important than O₂^- and·OH in the degradation of ARS. The intermediates and possible degradation pathways of ARS were discussed. Reuse and stability of G-TiO₂@Fe₃O₄ were also tested, and 88.3% photocatalytic activity was maintained after five cycles. Therefore, the proposed G-TiO₂@Fe₃O₄/PS not only had excellent photocatalytic activity, but also showed superior stability and reusability.

New insights in photocatalytic removal of Alizarin Yellow using reduced Ce3+/TiO2 catalyst

The present communication aims to obtain a novel Ce³⁺/TiO₂ thin film in a single step facile method using the in situ template process. The material was characterized by the XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), TEM (transmission electron microscope), and AFM (atomic force microscope) analyses. The thin film catalyst was intended to introduce in the degradation of one of potential dye Alizarin Yellow from aqueous solutions using the UV-A radiations. The mechanisms of degradation along with the physicochemical parametric studies were conducted extensively. The mineralization of pollutant and the replicate use of catalysts further enhance the applicability of present communication. Additionally, the real matrix treatment was conducted to simulate the treatment process.

TiO2 Photocatalyzed Degradation of the Azo Dye Disperse Red 1 in Aqueous Micellar Environments†

The photoinduced degradation of the azo dye Disperse Red 1 was studied in a microheterogeneous system comprising titanium oxide (TiO₂ ) and sodium dodecyl sulfate, exposed to UV light. Degussa P25, Anatase and TiO₂ synthesized in acidic conditions were supported on raschig rings. The TiO₂ photocatalyzed degradation is enhanced in the vicinity of the surfactant critical micelle value. Further increase on the surfactant concentration leads to a loss in photodegradation performance up to values equivalent to that observed without surfactant. Surfactant influence can be explained by two different phenomena taking place. The increasing concentration of surfactant leads to an increase in micellar concentration, inducing the incorporation of the dye to the hydrophobic moiety of the micelles, rendering the hydroxyl radical unable to interact with the dye. Similarly, the increased concentration of micelles at the photocatalyst/water interface might lead to a decrease in the number of active sites on the TiO₂ surface able to either generate reactive species and/or interact with de dye molecules. Additives such as H₂ O₂ , NaCl, Na₂ SO_4, and Na₂ CO₃ are able to override the influence of the surfactant both positively and negatively, being the final outcome of the influence highly dependent on the crystalline form of the TiO₂ photocatalyst.

Structure effects of amphiphilic and non-amphiphilic quaternary ammonium salts on photodegradation of Alizarin Red-S catalyzed by titanium dioxide

The role of surfactants such as single- and double-tailed tetraalkylammonium bromide and various non-amphiphilic tetraalkylammonium salts was investigated on the TiO₂photocatalyzed degradation of Alizarin Red-S under UV light irradiation.