Visible Light-Induced Photodegradation of Simazine in Aqueous TiO₂ Suspension

Abstract

The degradation of simazine (SMZ) in TiO2 suspension with the presence of H2O2 was investigated under the irradiation of 420 nm lamps. This process could be optimized by adjusting TiO2 dosage, initial concentration of H2O2, and the initial pH of the solution. The optimum TiO2 dosage was found to be 0.1 g/L, and the highest SMZ decay rate was achieved with the initial H2O2 concentration at 4 mM. Overdose of H2O2 is found to be more critical in jeopardizing the SMZ decay than the overdose of TiO2. A neutral initial pH level at 6.5 was found to be favorable for SMZ degradation. The presence of Cr(VI) significantly accelerated SMZ degradation in the TiO2/H2O2/vis (visible light) process. In addition, 10 simazine derivatives were identifed by liquid chromatography–mass spectrometry/mass spectrometry. It was suggested that dealkylation is the major pathway of SMZ photodecay in the TiO2/H2O2/vis process. The final product was found to be ammeline.

Sonophotocatalytic (42kHz) degradation of Simazine in the presence of Au–TiO2 nanocatalysts

“…On the other hand, further sonophotocatalytic irradiation (>7 h) was expected to completely mineralize the Simazine and the various intermediates produced during its degradation into CO 2 , H 2 O and other small molecular products. Based on the identification of the intermediates observed from the sonophotocatalytic mineralization of Simazine in the presence of Au-TiO 2 , and the available literature [11,[29][30][31], we proposed a pathway for the Simazine degradation as shown in Scheme 1. The similar kind of pathway can be proposed for the photocatalytic and sonocatalytic degradation of Simazine.…”

In-situ generated H2O2 induced efficient visible light photo-electrochemical catalytic oxidation of PCP-Na with TiO2

“…It has been reported that combination of TiO 2 and H 2 O 2 could degrade organic pollutants under visible light irradiation [19,21], the reason was proposed to the chemisorption of H 2 O 2 on the surface of TiO 2 to form yellow complex "titanium peroxide" ( Ti IV OOH) which could be excited by visible light [22][23][24], this was the reason for lower concentration of H 2 O 2 detected in the PEC system. Studies have demonstrated that the H 2 O 2 plays a dual role in enhancing the TiO 2 -based photocatalytic degradation of organic compounds by acting either as an electron scavenger to prevent the recombination of photogenerated electrons and holes or as a hydroxyl radical's source under UV irradiation [38,39].…”

“…Recently, H 2 O 2 combined with TiO 2 (H 2 O 2 /TiO 2 ) has been reported for photocatalytic oxidation of organic contaminants under visible light irradiation [19][20][21]. The general mechanism of H 2 O 2 /TiO 2 visible light driven photocatalysis was ascribed to the chemisorption of H 2 O 2 on the surface of TiO 2 and the subsequent formation of yellow surface complex of Ti IV OOH, which could be sensitized and excited under the visible light irradiation [22][23][24].…”

TiO2 Nanotubes Supported Cu Nanoparticles for Improving Photocatalytic Degradation of Simazine under UV Illumination

“…From the literature, many researchers have focused on TiO 2 nanoparticles (Degussa P25) [4,14]. However this is subject to higher cost, and may undergo aggregation as a result of nanosized instability [15,16]. In contrast, in this work, we synthesized TiO 2 in the form of nanotubes.…”