Shuhua Yao

Biosorption of methyl blue onto tartaric acid modified wheat bran from aqueous solution.

Tartaric acid modified wheat bran was utilized as adsorbent to remove methyl blue, a basic dye from aqueous solution. Batch experiments were carried out to study the effect of various experimental parameters such as initial solution pH, contact time, initial dye concentration and adsorbent dosage, on dye adsorption. The results showed that the modification of wheat bran by tartaric acid significantly improved its adsorption capacity, and made this material a suitable adsorbent to remove methyl blue. The adsorption capacity of modified wheat bran was about 1.6 times higher than that of unmodified one. The amount of methyl blue adsorbed was found to vary with initial solution pH, adsorbent dosage, contact time and initial methyl blue concentration. Kinetics study showed that the overall adsorption rate of methyl blue was illustrated by pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the data was tested. Both models adequately described the experimental data of the biosorption of methyl blue. The maximum adsorption capacity for methyl blue calculated from Langmuir model was 25.18 mg/g. The study has shown the effectiveness of modified wheat bran in the removal of methyl blue, and that it can be considered as an attractive alternative to the more expensive technologies used in wastewater treatment.

Preparation, Characterization and Photocatalytic Activity of Lanthanum Doped Mesoporous Titanium Dioxide

Lanthanum doped mesoporous titanium dioxide photocatalysts with different La content were synthesized by template method using tetrabutyltitanate (Ti(OC4H9)4) as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric differential thermal analysis, N2 adsorption-desorption measurements, X-ray diffraction, and UV-Vis adsorption spectroscopy. The effect of La3+ doping concentration from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was investigated. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of about 10 nm with high surface area of 165 m2/g. X-ray photoelectron spectroscopy measurements indicated the presence of C in the doped samples in addition to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecomposition showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradiation.

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Physical properties of nano-titania hollow fibers and their photocatalytic activity in the decomposition of phenol

A series of nano-titania (TiO2) photocatalytic materials with a hollow fiber structure were successfully prepared using tetra-n-butyl titanate (Ti(OC4H9)4) as precursor and cotton fiber as the template. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and N2 adsorption-desorption measurements were employed to characterize the morphology, crystal structure, and surface structure of the samples. The photocatalytic activities of the samples were studied by phenol photodegradation in water under UV irradiation. The effect of calcination temperature, photocatalyst dosage, initial concentration of phenol and irradiation time on the photodegradation of phenol was studied. Results showed that the TiO2 fiber materials have hollow structures, indicating that these materials had a large specific surface area. The fiber structure material showed better photocatalytic properties for the degradation of phenol than pure TiO2 under UV light, and the sample calcined at 500°C exhibited the highest phenol photodegradation efficiency. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed, the photocatalytic activity of TiO2 fiber remained ca. 90% of photocatalytic activity of the fresh sample after being used four times. Moreover, TiO2 fiber was easily recovered by centrifugal separation from water.

Adsorption properties and photocatalytic activity of TiO2/activated carbon fiber composite

Photocatalysts of titanium dioxide (TiO2) and TiO2/activated carbon fiber (TiO2/ACF) composite were prepared by sol-gel method, followed by calcining the pure TiO2 sols and the TiO2/ACF sols at 500°C for 2 h in a N2 atmosphere, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms measurement. Batch experiments were conducted to study the adsorption property of TiO2/ACF composite using methylene blue as adsorbate. The adsorption data obtained from different batch experiments were analyzed using pseudo-second-order kinetic model, the experimental data can be adequately described by the pseudo-second-order equation. The photodecomposition behavior of TiO2/ACF was investigated in aqueous solution using methylene blue as target pollutant. It was found that methylene blue could be removed rapidly from water by TiO2/ACF, the photocatalytic decomposition was obviously improved when the photocatalyst was used. Kinetics analysis revealed that the photocatalytic decomposition reaction can be described well by a first-order rate equation.

Photocatalytic degradation of methylene blue by visible-light-driven yttrium-doped mesoporous titania coated magnetite photocatalyst

ABSTRACTA novel kind of visible-light-driven photocatalyst (Y/MTiO2/Fe3O4) with yttrium-doped mesoporous titania (Y/MTiO2) shell and a magnetite core was prepared by coating photoactive Y/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4) with precursors of Y(NO3)3·6H2O and (Ti(OBu)4) in the presence of Fe3O4 particles, the MTiO2 shell was for photocatalysis, the Fe3O4 core was for separation by the magnetic field and the doped Y was used to enhance the photocatalytic activity of MTiO2. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the degradation rate of methylene blue (50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, the photocatalyst could be easily recovered from the medium by an...

Preparation and characterization of sulfur-modified mesoporous titania photocatalyst

Sulfur-modified mesoporous titania (S-MTiO2) was investigated as a potential photocatalyst under visible light. The photocatalyst was prepared by template method using thiourea and tetrabutyl titanate (Ti(OC4H9)4) as precursors and Pluronic P123 as template. The photoabsorbance of as-prepared photocatalyst was measured by UV-vis absorption spectroscopy, which confirmed the extension of absorption into the visible region. The microstructure of S-MTiO2 was characterized using X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The micro crystal of the S-doped photocatalyst consisted of anatase phase and no significant influence on the nature of crystal formation. X-ray photoelectron spectroscopy (XPS) measurements indicated the presence of C in the prepared photocatalyst in addition to S. The photo-catalytic performance was studied by photodegradation methyl orange (MO) in water under visible light irradiation. The calcination temperature and the doping content influenced the photoactivity.

Preparation, characterization of Fe, Ce Co-doped flower-like TiO 2 photocatalysts and their properties in photocatalytic oxidation of arsenite

Preoxidation process is usually needed in the treatment of arsenic containing water because arsenite (i.e., As(III)) is less easily to be removed by adsorption. Nano-scale titanium dioxide (TiO2) is an efficient photocatalyst for arsenite oxidation. In this study, a series of photocatalysts of un-doped, single-doped and co-doped flower-like TiO2 were successfully prepared by template method using Fe(NO3)3 · 9H2O, ammonium ceric nitrate and tetrabutyl titanate (Ti(OC4H9)4) as precursors and glucan as template. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photoabsorbance of the obtained catalysts was measured by UV–Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV light were estimated by measuring the oxidation rate of As(III) in an aqueous solution. The characterizations indicated that the prepared photocatalysts had flowerlike structures, consisted of anatase phase and possessed high surface area of ca. 160 m2/g. It was shown that the Fe, Ce co-doped flower-like TiO2 could be used as an effective catalyst in photocatalytic oxidation reactions. The synergistic effect of Fe and Ce co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of the co-doped flower-like TiO2 was also confirmed, the photocatalytic activity of flower-like TiO2 remained 88% of that of the fresh sample after being used four times.