Yinshan Jiang

Synthesis and photocatalytic activity of N-doped NaTaO3 compounds calcined at low temperature.

N-doped NaTaO(3) compounds (NaTaO(3-x)N(x)) were successfully synthesized using NaTaO(3) prepared at low calcination temperature as starting material and melamine (C(3)H(6)N(6)) as nitrogen source. The as-prepared NaTaO(3-x)N(x) samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra. The XRD results indicate that the crystallization temperature of NaTaO(3) is up to 700 degrees C and the doping of N does not lead to significant structural changes. Moreover, as observed by SEM images, the particle sizes of resultant NaTaO(3-x)N(x) are in the range of 100-150 nm, which are much smaller than NaTaO(3) particles synthesized by traditional solid state reaction method. The photocatalytic activities of NaTaO(3-x)N(x) were examined by methylene blue (MB) aqueous solution under UV light. It is found that the photocatalytic activity of NaTaO(3-x)N(x) depend strongly on the doping content of N, and sample NaTaO(2.961)N(0.039) shows the highest photocatalytic activity for the degradation of MB. Furthermore, it is also found that NaTaO(3-x)N(x) catalysts display super structural stabilities during photocatalytic degradation, and could recover their photocatalytic activity after calcination at 500 degrees C, suggesting a promising utilization of such photocatalyst.

A high-stability silica-clay composite: synthesis, characterization and combination with TiO2 as a novel photocatalyst for Azo dye.

A novel micro-mesopores composite material has successfully been synthesized at basic hydrothermal conditions using natural mineral montmorillonite (MMT) and tetraethoxysilane (TEOS). Two surfactants, cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG), have been employed in order to shape the pores in the composite. The resultant silica-clay has large surface area (472m(2)/g) and high hydrothermal stability, which makes it a potentially host-material for catalyst. The molecular size of different surfactant leads to the multi-peak distribution of pore size, and the surfactant of larger size (PEG) corresponds to the formation of larger pores. Moreover, the photocatalytic results show that, comparing with pure TiO(2) particles, the loaded TiO(2) on such silica-clay shows higher photodegradation rate of methyl orange (MO) in aqueous. And another porous aluminosilicate host, zeolite, was also discussed for comparison.

The interaction of cellulose and montmorillonite in a hydrothermal process

In this paper, the interaction of cellulose and montmorillonite in a hydrothermal process was discussed. The preparation of the composite was performed at 230 °C for different periods of time from 0.5 to 16 h. The hydroxypropyl methyl cellulose was set to 50 wt.% in the composite and multiple sets of data were compared. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry-differential thermal analysis, specific surface area and electric potential for evaluation of interactions. Hydrochar is a solid carbon-rich mixture produced from the hydrothermal carbonization of the cellulose. The cellulose can be adsorbed at the surface of montmorillonite. The pores of montmorillonite are partially blocked by the hydrochar. The state of the hydrochar has a significant effect on the order of montmorillonite. The zeta potential of the composite is mainly affected by hydrochar. In turn, the Fourier transform infrared spectroscopy results indicate that montmorillonite affects the hydrochar structure, and the thermal stability of hydrochar is improved. The experimental results show that the presence of hydrochar in the composite causes significant changes in surface properties and the interlayer structure. Meanwhile, montmorillonite plays a protective role on the hydrochar.Graphical Abstract

The role of potassium chlorate on expansion of dickite layers and the preparation of a novel TiO2 impregnated dickite photocatalyst using expanded dickite as carrier

The layered dickite particles were expanded by rapidly heating the mixture of dickite–urea intercalation complex and KClO3. Then a novel TiO2 impregnated dickite photocatalyst was prepared from expanded dickite (used as a carrier) and TiOSO4 aqueous suspension. The resulting expanded dickite particles and the reaction mechanism were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry and specific surface area test. Results showed KClO3 reacted rapidly with the urea molecules remaining on the surfaces of the dickite–urea intercalation complex in the rapid heating process. A large number of gases produced from the reaction expanded the dickite layers. The expanded layers could reach 20 nm thick and their average specific surface area was nearly ten times larger than that of raw dickite. The exposed inner surfaces of the expanded dickite were new places where TiO2 particles deposited. Photocatalytic activity was evaluated by the degradation of methyl orange in aqueous solutions. The TiO2/dickite photocatalyst had a porous layer structure and nano-size TiO2 particles, and demonstrated an enhanced adsorption and photocatalytic ability for the removal of methyl orange.

Opal promotes hydrothermal carbonization of hydroxypropyl methyl cellulose and formation of carbon nanospheres

Hydrothermal carbon nanospheres were prepared by introducing opal into the hydrothermal carbonization system of hydroxypropyl methyl cellulose (HPMC). Then the effects of opal on hydrothermal carbonization of HPMC were investigated after different reaction durations (105–240 min). The reaction products were characterized by elemental analysis, gas chromatography-mass spectrometry (GC-MS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. Results of elemental analysis indicated that the H (hydrogen) and O (oxygen) content of HPMC decreased through dehydration, demethylation, decarbonylation and hydrolysis reactions, forming hydrochar with higher carbon content. The addition of opal was confirmed to accelerate the hydrolysis of HPMC. N2 adsorption–desorption tests and SEM analysis showed that opal with a large specific surface area adsorbed HPMC hydrolysis products, such as furans, and facilitated furan cyclodehydration on its surfaces to form cross-linked carbons, which contributed to the quick formation of hydrochar. Moreover, the adsorption by opal also inhibited hydrochar aggregation, so the final hydrothermal carbon spheres had sizes of 20–100 nm.

UV shielding performance of illite/TiO2 nanocomposites

Illite/TiO2 nanocomposites have been successfully synthesized by the hydrothermal method. Phase and microstructural analysis confirmed that TiO2 nanocrystals were loaded on the surface of illite with a strong chemical bond. The as-prepared illite/TiO2 samples presented high UV shielding performance with increasing TiO2 content. The PIT-50% sample exhibited the best UV shielding performance, blocking almost 100% of UVC, over 98% of UVB and nearly 60% of UVA while having poor photocatalytic activity. Furthermore, the illite/TiO2 powders were dispersed more homogeneously on the matrix when compared to TiO2, and their photocatalytic activity could be adjusted to a suitable range to achieve better UV shielding performance. Therefore, unlike the traditional rutile UV blocker, this novel illite/anatase blocker can display desirable UV shielding properties, especially at longer irradiation times, and the fabric maintained 71.35% tensile strength after the UV aging test with half the amount of TiO2. All these results indicate that illite/anatase nanocomposites are promising UV shielding materials for textiles and polymers, with regard to both cost and performance.