Guangyue Ding

Preparation and photocatalytic activity of BiOCl catalyst

Abstract The BiOCl powders prepared by the hydrolysis method were investigated with the X-ray diffractometry (XRD), scanning electron microscopy (SEM) and differential thermal analysis (TG-DTA). The results show that the powders are of the tetragonal primitive crystal structure, composed of homogeneous particles of fine ferrite plates, and stable in the temperature range of 40-600 °C. In addition, the photocatalytic activity of BiOCl powders was evaluated by methyl orange (MO) in aqueous solution illuminated by xenon-lamp, and the effect of the BiOCl amount on the photocatalytic activity was investigated. Moreover, the photocatalytic properties of BiOCl and TiO2-P25 were also compared. The results show that the favorite amount of BiOCl powders is 1.0 g/L for the MO degradationand the photocatalytic activity of the BiOCl catalyst is comparable to the TiO2-P25 catalyst under the same experiment condition.

Preparation and photocatalytic properties of ilmenite NiTiO3 powders for degradation of humic acid in water

The powders of ilmenite structure NiTiO3 were prepared by a modified Pechini process using tetrabutyl titanate and nickel acetate as raw materials, and using citric acid and ethanol as a chelating agent and a solvent respectively. The powder samples were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). The photocatalytic activity of NiTiO3 under the irradiation of ultraviolet rays (UV) light was evaluated by degrading humic acid (HA) in water as a probe reaction. The possible photodegradation mechanism was studied by the examination of active species ·OH, ·O2−, and holes (h+) through adding scavengers. The TG-DTA and XRD results indicated that the good crystal structure of ilmenite phase NiTiO3 could be obtained when the Ni-Ti citrate complex was calcined at 600°C. The photocatalytic activity experiments indicated that NiTiO3 had favourable photocatalytic activity under the irradiation of UV light, and the photocatalytic degradation rate of HA reached 95.3% after a 2.5 h reaction with the photocatalyst calcined at 600°C and a photocatalyst dosage of 0.4 g/L. The possible photocatalytic mechanism was deduced that holes (h+) and ·OH radicals are the major reactive active species in the photocatalytic reaction, and dissolved oxygen plays a weak role in the degradation of HA.

Synthesis of BiOCl photocatalyst by a low-cost, simple hydrolytic technique and its excellent photocatalytic activity

A novel photocatalyst, bismuth oxychloride (BiOCl) micro-nano particles with a fine ferrite plate structure, was prepared by a low-cost, simple hydrolytic method. The as-prepared BiOCl was characterized by scanning electron microscopy (SEM), thermogravimetric analysis-differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectra (DRS). The effects of preparation conditions such as sodium dodecyl benzene sulfonate (SDBS) dispersant, HCl concentration, and heat treatment temperature on BiOCl performances were investigated. Moreover, its photocatalytic activity was evaluated on the degradation of methylene orange (MO) and was compared with that of TiO2 (P25). The experimental results confirmed that BiOCl micro-nano particles prepared with SDBS, the HCl concentration of 1.5 mol/L, and the heat treatment temperature of 80°C exhibited the best performance for the photodegradation of MO solution, and they showed good stability and better photocatalytic activity than P25 photocatalyst.

Study on the solubility and morphology of calcium sulfate dihydrate in nitric acid and phosphoric acid aqueous medium

In order to investigate the solubility of CaSO<inf>4</inf>·2H<inf>2</inf>O at different contents of H<inf>3</inf>PO<inf>4</inf> and HNO<inf>3</inf> aqueous medium, a series of tests was designed for determining the solubility of CaSO<inf>4</inf>·2H<inf>2</inf>O at 25°C and 65°C in different acidic concentration solvents, the crystal morphology of the deposition solid-phase after liquid-solid equilibrium was examined by microscope, and the crystalline of the deposition solid-phase was characterized by XRD. The results showed that the solubility of CaSO<inf>4</inf>°2H<inf>2</inf>O increases gradually with the increase of H<inf>3</inf>PO<inf>4</inf> and HNO<inf>3</inf> content, the solubility at 65°C is always higher than at 25°C. In the mixed acid solvent system, when changing the content of HNO<inf>3</inf> at a fixed H<inf>3</inf>PO<inf>4</inf> content of 20%, the solubility of CaSO<inf>4</inf>·2H<inf>2</inf>O increases with the increasing content of HNO<inf>3</inf>; however when changing the content of H<inf>3</inf>PO<inf>4</inf> at a fixed HNO<inf>3</inf> content of 10%, the solubility first increases and then decreases with the increase of H<inf>3</inf>PO<inf>4</inf> content. The micrographs showed that the crystal morphologies of CaSO<inf>4</inf>·2H<inf>2</inf>O were also changed at the different experimental conditions, but basically were rod-like and flat-long flake. XRD analysis showed that the deposition solids were basically a stable form of CaSO<inf>4</inf>·2H<inf>2</inf>O, but when both the H<inf>3</inf>PO<inf>4</inf> concentration and HNO<inf>3</inf> concentration is 20%, the characteristic peaks of CaSO<inf>4</inf>·2H<inf>2</inf>O all disappear, and only at 2θ = 25.41 ° a weak peak of CaSO<inf>4</inf>·1/2H<inf>2</inf>O comes forth, this means the crystal type of deposition solid-phase at this condition has been transformed and the crystal particles are also very small.