Lai Sin Yuan

Textile/Al2O3–TiO2 nanocomposite as an antimicrobial and radical scavenger wound dressing

Improving the antimicrobial activity and radical scavenging ability of a textile-based nanocomposite (textile/TiO2, textile/Al2O3/TiO2, textile/Al2O3 and textile/Al2O3–TiO2 bimetal oxide nanocomposite) is the key issue in developing a good and flexible wound dressing. In this work, flexible textile attached with Al2O3–TiO2 nanoparticles was prepared by dipping the textile in a suspension containing Al2O3–TiO2 nanoparticles (150 mmol l−1). The mean radical scavenging ability for textile/TiO2, textile/Al2O3/TiO2, textile/Al2O3 and textile/Al2O3–TiO2 bimetal oxide nanocomposites as measured by liquid ultraviolet visible spectroscopy (UV-Vis) coupled with dependence formula was 0.2%, 35.5%, 35.0% and 38.2%, respectively. Based on the X-ray diffraction (XRD) patterns, the preface reactive oxygen species (ROS) scavenging ability shown by the textile/Al2O3–TiO2 bimetal oxide nanocomposite is most probably caused by the crystal structure concluding in a corundum-like structure, with Al3+ ions filling the octahedral sites in the lattice. Increased antimicrobial activity measured by optical density at 600 nm recorded for textile/Al2O3–TiO2 bimetal oxide nanocomposites showed better interaction between Al2O3 and TiO2 nanoparticles. This good interaction is expected to lead to better antimicrobial and radical scavenging ability as shown by the E. coli and human skin fibroblast (HSF) cytotoxicity tests, respectively.

Titania-Loaded Coal Char as Catalyst in Oxidation of Styrene with Aqueous Hydrogen Peroxide

Abstract Titania-loaded coal char catalyst was successfully prepared. The preparation steps involved pyrolysis of low rank coal at different temperatures and durations, sulfonation, impregnation of titanium(IV) isopropoxide, and then heating at 110 °C. It is found that the coal chars’ surfaces were rough after sulfonation and impregnation, while large pore volume, high surface area and carbon composition were observed at low pyrolysis temperature for short duration. These properties contributed to high selectivity towards benzaldehyde (> 90 %) at 600 °C (0.5–2 h)) in styrene oxidation using aqueous hydrogen peroxide as the oxidant.

Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide

AbstractThis research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at room temperature by mixing imine ligand and Ti(IV) sulphate solution. The amorphous, solid complex formed was further silylated with octadecyltrimethoxysilane (OTMS) to induce hydrophobicity. The composition of the resulting silica functionalized with silylated Ti-salicylaldimine complex was varied with Ti:OTMS molar ratio in the range of 1:1/4 to 1:4 at room temperature. The successful attachment of alkylsilyl groups to silica functionalized with Ti-salicylaldimine complex was proven by the FTIR and 29Si solid state NMR spectra. The FTIR spectra showed increasing peak area for sp 3 C-H stretching mode (ca. 2919 cm−1 and 2850 cm−1) and decreasing peak area for Si-OH band with increasing amount of OTMS. TGA showed less water content with higher amount of alkylsilyl groups in the catalyst. This is in agreement with the lower kinetic rate of water adsorption capacity for the hydrophobic catalysts prepared. It was observed that the hydrophobic, silica functionalized with silylated Ti-salicylaldimine complex exhibited higher substrate conversion and reusability compared to the non-silylated catalyst. Graphical AbstractSilica functionalization with silylated Ti-salicylaldimine complex was varied with octadecyltrimethoxysilane (OTMS) concentration to induce hydrophobicity. It was found that the higher degree of hydrophobicity has decreased the water content. Hence, the catalytic activity and TON for Ti increased. It showed that the surface property is important in the design of catalysts.

Synthesis of titania with different shapes

Titania (TiO₂) has been an important renewable material that is able to convert solar energy into chemical energy in recent years. Therefore, the main focus of this paper centers around different strategies and precursors to prepare TiO₂ with various shapes, e.g. perforated hollow TiO₂, anatase hollow TiO₂ spheres, well-aligned TiO₂ and rambutan-like TiO₂/liquid crystal composite, so as to utilize these materials in an environmental-benign way.