Ming Xiao,Ruixue Li,Jinglin Yin,Junhui Yang,Xinyu Hu,Hongbo Xiao,Wenlei Wang,Ting Yang
The treatment of arsenite pollution in water has always been concerned. Oxidation of high toxic As(III) to relatively low toxic As(V) by efficient photocatalytic oxidation technology is a research hotspot. This paper is focused on the active photocatalyst of TiO 2 @Fe 3 O 4 composites synthesized by a simple hydrothermal method for the efficient photocatalytic oxidation of As(Ⅲ). The successful construction of Ti–O–Fe interface bonds between TiO 2 and Fe 3 O 4 significantly promoted the transfer efficiency of photo-generated carriers, and further rapidly improved the photocatalytic oxidation efficiency of As(Ⅲ). The application results showed that the constructed TiO 2 @Fe 3 O 4 photocatalyst with 0.10 g Fe 3 O 4 (TF-0.10) could complete the transformation from As(Ⅲ) (10,000 μg/L) to As(Ⅴ) within 4 min with a high oxidation ratio of 100% and maintained the good properties with unchanged crystal structure after five cycles. Furthermore, the photocatalytic properties of TiO 2 @Fe 3 O 4 composites were still stable under different pH values. Electron paramagnetic resonance (EPR) consequence displayed that the superoxide radical (‧O 2 — ) and hole (h + ) were the main intermediate product in the arsenic photocatalytic oxidation system, and hydroxyl radical (‧OH) had little effect on this oxidation system. The possible mechanism of As(Ⅲ) photocatalytic conversion was further explored based on the results of the data analysis. Furthermore, this work provides a potential new idea for the practicability of efficient photocatalytic arsenic oxidation.
Hongfei Liu,Kexu Wang,Dongke Zhang,Dishun Zhao,Jianhua Zhai,Wenguang Cui
In this paper, an organic-inorganic hybrid material was synthesized via a simple but effective method, the novel material PGO-TiO 2 /Fe 3 O 4 (PGTF) was produced by loading TiO 2 and Fe 3 O 4 onto polymeric ionic liquid(PIL) functionalized graphene oxide(GO). The successful synthesis of PGTF and related structural feature were confirmed by a series of characterizations. The results of UV diffuse reflectance (DRS) demonstrated that the incorporation of PGO-Fe 3 O 4 to TiO 2 shifted the light absorption of TiO 2 from ultraviolet (UV) to visible region. The band gap energy of the PGTF reduced to1.92 eV as compared to TiO 2 (3.12 eV). Different materials were used to remove methyl orange (MO) from the aqueous solution. The results showed that PGTF had a superior capacity to remove dye due to the synergistic effects of adsorption and photocatalysis . The excellent adsorption properties may result from the high specific surface area of GO and the –NH 2 in the PIL. The polyionic liquid absorbed electrons due to the electrostatic action of the cation head in the polyionic liquid and GO which had high conductivity favored electron transport . The photocatalytic effectiveness increased as a result of the separation of photoexcited electron-hole pairs. The Langmuir model was investigated to evaluate the adsorption equilibrium behavior of MO dyes by PGTF. The maximum adsorption capacity( Q m ax ) was 67.88 mg/g for MO dyes. The pseudo-second-order kinetic model, with a correlation coefficient of 0.999, provided a good fit for the adsorption kinetic processes. The adsorption rate constant K 2 obtained by this model is 0.0072 g/(mg*min). The degradation rate constant of PGTF for MO in the photocatalytic stage was 0.00881 min −1 , which exhibited 3.7, 7.5 and 3 times higher than that of TiO 2 , FT and GTF. The main reactive species in the degradation process were O 2 − 、·OH、h + . PGTF had excellent repeatability because of the presence of Fe 3 O 4 . They can be easily separated from the water. These results indicated that the PGTF composites hold great potential for removing MO from wastewater.
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