Papers by Author: Xue Fei Lei

Abstract: The paper preliminary studied the photocatalytic efficiency of the filter residue of the acidolysis of high titanium slag (RAHTS) with hydrochloric acid, and explored the photocatalytic efficiency on the acid methyl orange solution under the mercury lamp irradiation. With RAHTS performing as a raw material to react with hydrochloric acid, and then the substance content, nature and catalytic efficiency of the filter residues were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photocatalytic reaction apparatus. Through the experimental investigation, the photocatalytic degradation efficiency on the methyl orange of the filter residues increased with the acid-sludge ratio, reaction time, reaction temperature, and the concentration of hydrochloric acid. When the temperature was 100°C, the reaction time was 4 h, the concentration of the hydrochloric acid was 6 mol/L, the acid-sludge ratio was 1, the filter residues showed a best photocatalytic degradation efficiency. Under that experimental condition, the degradation rate was as high as 85.1%.

Abstract: In this paper, steel slag as the main raw material, modified steel slag adsorbent was prepared using steel slag and the active carbon as the starting materials. The influences of doping substance, the particle size, calcining temperature and doping ratio on the decoloration rate of methyl orange wastewater were investigated. The results showed that the decoloration rate of methyl orange can reach 93.62% when the doping substance was the activated carbon, the particle size was 120 mesh, the calcining temperature was 700°C, the doping ratio was 1:1.

Abstract: Iron titanate photocatalysts were synthesized by the high-energy ball milling method with titanium ore as the starting material. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), thermal gravity and differential thermal analysis (TG-DTA), UV-visible diffuse reflectance absorption spectra (UV-Vis), photoluminescence emission spectra (PL) and photocatalytic degradation measurement were conducted to characterize the structure, surface status, UV-visible light response and performance of the obtained sample. After low temperature calcination (above 400 oC), the photocatalytic activity of iron titanate catalyst decreased gradually, which was mainly due to the decrease of surface hydroxyls and reactant adsorption capability.

Abstract: The paper investigates the feasibility to reduce Cr (VI) from the aqueous solution by sulfate-modified titanium-bearing blast furnace slag (STBBFS) prepared with the different preparation method. The different photocatalysts were examined by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra and scanning electronic microscopy (SEM). The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr (VI) under UV-vis light irradiation. For the photocatalytic reduction of Cr (VI), the photocatalytic activities of STBBFS catalysts were found to be strongly dependent of absorbance in UV-visible region, adsorption capacity and surface acidity, and STBBFS prepared by dry-process showed a higher photocatalytic activity compared to that prepared by hydro-chemistry method.

Abstract: The four main effect production factors, doping rate, calcination temperature, soaking time and heating rate, are chose to design experiments based on the orthogonal table L₉(₃⁴) to prepare urea-modified titanium ore (UTO) sorbents. And the decoloration efficiency of methyl orange is examined by using UTO as sorbents under dark-state absorption. Based on the orthogonal experiments, we obtained the optimal operating parameters: urea 8.0wt%, soaking time 3h, calcination temperature 300°C and heating rate 10°C/min. As the preparation condition was run at the optimal conditions, the decoloration efficiency of methyl orange reached 98.1%, which was significantly better than the undoped samples. Thus, it is feasible to treat dye wastewater by these UTO sorbents.

Abstract: Using calcined sulfate-modified titanium-bearing blast furnace slag (STBBFS) as photocatalyst, decolorization efficiency of methyl orange (MO) in the presence of Cr(VI) were studied. The effect of solution pH on the decolorization efficiency of MO and reduction efficiency of Cr(VI) have been investigated. The results indicate that the acidic solutions are favorable for the photocatalytic oxidation of MO in the presence of Cr(VI), and the optimum pH for oxidation of MO is 1.5. The increasing of photocatalytic activities in the compound system can be attributed to five main reasons: (1) the redox reaction between Cr(VI) and MO; (2) adsorption of Cr(VI) species and dye molecule onto STBBFS surface; (3) the visible light irradiation; (4) Cr(VI) species reduced to Cr(III) by Mn2+ in STBBFS photocatalyst; (5) Moreover, the addition of Cr(VI) species able to act as electron scavengers to catalyst surface promotes the effective separation of electron-hole, and hence promote the increase of decolorization efficiency of MO and reduction efficiency of Cr(VI) in Cr(VI)-MO system under visible irradiation. UV-vis spectral analysis indicated that MO was completely mineralized in the presence of Cr(VI) after 240 min. FTIR spectral analysis showed that all these characteristic peaks of Cr(VI) and MO disappear after photoreaction, indicating the degradation of Cr(VI) and MO.

Abstract: Using sulfate-modified titanium-bearing blast furnace slag (STBBFS) as photocatalyst, decolorization efficiency of methyl orange (MO) in the absence and presence of Cr(VI) were studied. The effect of the initial concentration of Cr(VI) on the decolorization efficiency of MO at pH=1.5 has been investigated. The results indicate that the acidic solutions are favorable for the photocatalytic oxidation of MO in the absence and presence of Cr(VI), and the optimum pH for oxidation of MO is 1.5. In the presence of Cr(VI), decolorization efficiency and adsorption efficiency of MO rapidly increased with the increase of Cr(VI) concentration, indicating a strong promoting effect of Cr(VI) to oxidation of MO. The increasing in decolorization efficiency of MO in the compound system can be attributed to three main reasons: (1) oxidation of MO by Cr(VI); (2) the high affinity of MO to catalyst surface; (3) Moreover, the addition of Cr(VI) species able to act as electron scavengers to catalyst surface promotes the effective separation of electron-hole in the photocatalytic processes, and hence promote the increase of decolorization efficiency of MO in Cr(VI)-MO system under visible irradiation. FTIR spectral analysis showed that all these characteristic peaks of Cr(VI) and MO disappear after photoreaction, indicating the degradation of Cr(VI) and MO.

Abstract: The photocatalytic reduction experiments of Cr(VI) over the sulfate-modified titanium-bearing blast furnace slag photocatalyst under UV-vis light irradiation in the absence/presence of citric acid (0≤[citric acid]≤4 mM) were performed at different pH and different initial concentration. In the presence of citric acid, the photocatalytic reduction efficiency of Cr(VI) was significantly enhanced and kinetic constants of the compound system (in the presence of photaocatalyst, citric acid and Cr(VI))was nearly 9.2 times than that in the absence of citric acid. This enhanced efficiency may be attributed to the effective separation of electron-hole in the presence of citric acid. The maximum rate of Cr(VI) reduction was obtained for an initial citric acid/Cr(VI) molar ratio, R=3.75, a further increment in R being disadvantageous; however, the photocatalytic reduction efficiency of Cr(VI) in the presence of citric acid was always faster than in its absence. The synergistic effect factor is always greater than 6 in the compound system, indicating that a marked synergistic effect between the photocatalytic reduction of Cr(VI) and citric acid.