Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO2

Abstract

Rare earth element La-doped TiO2 (La/TiO2) was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO2. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO2, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO2 with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L−1 was removed after 120 min in a solution of pH 4.4 with an La/TiO2 amount of 0.5 g·L−1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO2 still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.

Synergistic Mechanism of Rare-Earth Modification TiO2 and Photodegradation on Benzohydroxamic Acid

“…RE/TiO 2 were prepared by the sol-gel method according to previous research [10]. Rare-earth nitrate in the required stoichiometry was mixed with 2 mL deionized water, 2 mL acetic acid and 10 mL absolute ethanol, and the mixture solution after stirring was noted as solution A.…”

“…For example, there needs to be 5 or more days to get to the removal efficiency of 85% for benzohydroxamic acid (BHA, the most widely-used collector in the flotation industry at present) with the method of biodegradation [9]. However, our previous studies indicated that La/TiO 2 and Yb/TiO 2 possessed high photodegradation activity to BHA (the removal efficiency was up to 90% in 2 h) [10]. TiO 2 has been considered as the most promising photocatalyst among various semiconductor photocatalyst materials due to its benign physicochemical property and low cost [11].…”

Effects of Rare Earth Elements and Nitrogen Co‐Doped on the Photocatalytic Performance of TiO2

“…Zhang and Parida reported that La‐doped or Ce‐doped TiO 2 can inhibit the anatase to rutile phase transformation and extend light‐absorption to the visible region, thus greatly improving the photocatalytic performance of TiO 2 . In addition, studies showed that doping with rare earth elements such as La, Ce, Gd, and Sm can inhibit electron‐hole recombination, thus improving the photocatalytic efficiency . Xu et al .…”

Characterization and Computation of Yb/TiO2 and Its Photocatalytic Degradation with Benzohydroxamic Acid

“…Pure TiO 2 and Yb/TiO 2 catalysts were synthesized by sol-gel method [ 13 , 14 , 15 ]. The detailed prepared processes are as follows.…”

“…However, five or more days were needed to obtain a removal efficiency of 85% under the conditions of additional nutrition. Our previous study indicated that La/TiO 2 possessed high activity with respect to BHA [ 13 ]. However, the products of BHA and the oxidation mechanisms were not discussed in the previous study.…”