Papers by Author: Yang Cao

Abstract: In order to find an effective way to degrade the effluent, the Cu/TiO2, La/TiO2, Cr/TiO2 films with unique 3-D network structures were prepared using Ti(OBu)4 by sol-gel method loaded on the gauzes. These films structures were characterized by means of XRD and SEM. The effects of doped TiO2 films and combination of magnetic field and doped TiO2 films on the degradation of methyl orange (MO) were studied. The results indicated that after combinating the magnetic field, the photocatalysis efficiency of doped TiO2 films have been improved,especially the influence on Cu/TiO2 film was more obvious than other films.When magnetic intensity was around 30mT ,the MO degradation ratio went up to 60% by using Cu/TiO2 films.But the influences of magnetic intensity on photocatalytic activities of doped TiO2 films had a maximum value which was 30mT.

Abstract: Fossil oil as a nonrenewable energy resource, with the development of global economy, the need for energy increases continuously. Biodiesel is a renewable and clean energy, which is made by vegetable oil or animal fat and methyl alcohol to produce fatty acid esters. This research shows that waste cooking oil can be used for biodiesel by the means of esterification and transesterification, at the same time waste cooking oil can be reused. Through orthogonal design, the optimum conditions are that at first ,using sulfuric acid 5wt% of waste cooking oil as catalyst, the molar ratio of methanol and oil is 30:1, the reaction temperature is 65 °C，and the reaction time is 3h ; the second step, KOH is used as catalyst, the amount of the KOH is 0.15wt%, the levels of methanol to oil ratio is 25:1, reaction temperature is 60 °C， reaction time is 1h. The maximum yield of biodiesel is 93.24wt%.

Abstract: Nano-titanium dioxide (N-TiO2) have already been studied and applied in the different fields due to its special surface, quantum size effect and high photocatalysis etc super properties. As a kind of biomaterials, biocompatibility and corrosion resistant of titanium are closely related to the surface oxide films. In this paper, nano-titanium dioxide with uniform granularity was synthesized using coprecipitation method. The effects of reactant mixture ratio and sintering temperature on synthesized N-TiO₂ were discussed. X-ray diffraction and Fourier transform infrared spectroscopy were employed to analyze structure of N-TiO₂. The results showed that prepared N- TiO₂ were all anatase and rutile coexistence and the larger ratio of carbamide to titanium oxysulfate (CO(NH₂)₂/TiOSO₄) is propitious to formation of metatitanic acid (TiO(OH)₂) precipitate. Meanwhile, with CO(NH2)2/TiOSO4 increasing, the start time and end time of precipitate decreased. The method used in this paper was a kind of simple process and easy to do.

Abstract: Titanium oxide (Ti-O) films have been widely used in the fields of electron, photology and medicine due to its distinctive optical, electrical and chemical properties. In this paper, Ti-O films were synthesized by micro-arc oxidation firstly, and then surface was modified by NaOH alkali solution under different treatment time. The wettabilities of as-prepared films were investigated by contact angle measurements using four common liquids. nanoindentation was adopted to obtain the films’ nanohardness and modulus. The results show that Ti-O films tend towards hydrophilia and its surface energy increased after alkali treatment, but no obvious effects to nanohardness and modulus of Ti-O films. Surface roughness of Ti-O films increases after alkali treatment firstly, but decreased with continuing to increasing the times of alkali treatment.

Abstract: Two Schiff bases of chitosan (CTS) were synthesized from 4-methoxylbenzylaldehyde (CH₃O-CTS) and 4-methylbenzylaldehyde(CH₃-CTS). The Schiff bases were characterized by FTIR, DSC-TGA, solid ¹³C CP-Mas NMR, and elemental analysis. Antibacterial activities of the Schiff bases against Escherichia coli and Staphylococcus aureus were measured by the optical density method. The antibacterial activity of the Schiff bases is better than that of the original CTS. The IC₅₀ of CH₃O-CTS and CH₃-CTS against Escherichia coli is respectively 40.3 ppm and 43 ppm, which being 38.5 ppm and 39.5 ppm against Staphylococcus aureus, lower than IC₅₀ of chitosan, being 59.5 ppm and 52 ppm against Escherichia coli and Staphylococcus aureus, respectively.

Abstract: TiO₂ thin films were prepared successfully by dip-coating technique and sol-gel method on quartz glass plate. The photocatalytic properties of the fabricated TiO₂ thin films to decompose the Methyl orange(MO) solution with or wihtout ultrasonic vibrations were investigated. Experimental results showed that TiO₂ thin films had best photocatalytic properties when it was coated four layers and calcined at 500°C. The sonophotocatalytic technology is more effective for the decomposition of methyl orange than single TiO₂ photocatalytic,the degradation rate increased by 35%.In addition,the degradation rate is affected by reaction time, the impact of ultrasonic power.

Abstract: Titania nanotube arrays were fabricated in deionize water and glycerol mixed electrolyte containing a certain amount of NH₄F. Three different polishing methods were used for pretreatment of Ti substrates: polished by hand with abrasive paper, by polishing machine, or by chemical polishing fluid (HF:HNO₃=1:4, in volumetric ratio). The morphology of three different samples were imaged by scanning electron microscopy, and their photoelectrical properties were studied as well. Experimental results showed that Titania nanotube arrays grown on the Ti substrate and polished by polishing fluid has highly-ordered and well-defined nanotube structure. The effects of anodization potential and duration on synthesis of highly-ordered TiO₂ nanotubes were also studied in this paper. Both the layer thickness and nanotube diameter linearly increase with the increasing potential. The layer thickness also increases with prolongation of anodization time. By optimizing the preparation conditions, we can successfully control the geometrical structure of TiO₂ nanotube arrays with diameters in the range between 50 and 200 nm and the layer thickness between 800 and 2000 nm.