Papers by Author: Ching Hsing Lin

Abstract: The La/TiO2 photocatalyst was prepared by lanthanum into TiO2 structure in a sol-gel process. The catalyst was characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), ESCA, and Brunauer Emmett Teller (BET) analyses. Photocatalytic activities of the supported catalysts were examined through decomposition process of azo-dye Acid Yellow 17 solution under UV irradiation. The results showed that the particle size of TiO2 is about 20 nm, and the particle of La/TiO2 is about 10 nm. The crystal structure is mainly in anatase phase, the contents of the rutile phase increase with the increase of the amount of doped lanthanum. The adsorption capacity of La/TiO2 catalysts increases with lanthanum dosage in the acidic solution. The contribution of actual photodecomposition was determined by desorption process, after the photocatalytic reaction. In the acidic solution, better photodecomposition efficiency is achieved than in the neutral or alkaline solution. The experiments demonstrated that the optimum doping of La at 10 mol %, the maximum photodecomposition in dye concertration at 15 mg L-1 and photocatalytic dosage at 0.75 g L-1, achieving the highest effect.

Abstract: Pd/SDB (Styrene Divinylbenzene Copolymer), a hydrophobic catalyst, has been used for the destruction of volatile organic compounds (VOCs) in wastewater. Although the catalysts performed well in low VOC concentrations, they were not as effective in high VOC concentrations because of the heat removal problem. On the other hand, Pt/Zeolite contains a high silica to alumina ratio, which gives it hydrophobic characteristics and allows it to endure significantly higher temperatures than Pd/SDB. Hence, they were chosen for the treatment of wastewater containing high VOC concentrations. As expected, the catalysts presented both high conversion rates and good stability maintenance. Because of their high stability and rapid regeneration, the catalysts were regarded to be promising for industrial applications. In this study, the noble metal content of Pt/Zeolite amounted to 1.5 wt.%, and that the different temperatures and pressures collocating with different weight hourly space velocity (WHSV) were used to test the VOCs conversion efficiency. The results showed that the best reduction temperature was 450°C below the temperature- programmed reduction (TPR) process. The reaction system consisted of a continuous dripping flow with a fix-bed system and proportional integral derivative (PID) temperature controller. Selected VOCs such as methanol, ethanol, propanol and formaldehyde were investigated over the catalyst. Qualitative and quantitative analysis of the reagents and the potential organic intermediates was determined using gas chromatography with a flame ionization detector (FID). The experimental results indicated that the reaction rate is inversely proportional to the molecular weight for the compounds with the same functional group. For the same molecular weight, aldehyde is easier to destroy than alcohol. Ethanol and propanol, atypical products of incomplete oxidation of alcohols, were detected in the reaction gas. To minimize the energy consumption, we preferred liquid phase reaction since the heat of reaction could maintain the reaction temperature.

Abstract: The Dye-Sensitized TiO2 thin film fabricated by TiO2 nanoparticles is a novel technology with advantage in low cost, little pollution and simple in manufacturing process. The fiber-shaped reacting sites provide enlarged photo-sensing area of the TiO2 thin films. Natural dye of TCPP was applied to improve the photo absorbability in this study. Besides, a novel plasma surface activation technique employed on the thin film showed well performance compared with previous reports by heating methods. The SEM images demonstrate that the nano-TiO2 composites deposited on the fiber substrate. Degradation of acetone under 365 and 420 nm light irradiation were conducted to evaluate the photocatalytic ability of the TiO2 and TCPP/TiO2 thin films. While TiO2 thin films gel catalyst showed good photocatalytic performance with a high degradation efficiency of 99.9%, only about 80% conversion efficiency was achieved by the TCPP/TiO2 thin films reactor under 365 nm light irradiation. Although the TCPP dye on TiO2 nanoparticle shows beneficial reflection intensity in 420 nm, the acetone degradation capability of TiO2 and TCPP/ TiO2 thin films reactor decreased about 30% and 25% respectively compared with the degradation efficiency under 365 nm.

Abstract: The TiO2 thin films were coated on the 100 meshes stainless steel 304 (SS304) sieves by using the sol-gel method followed by a thermal treatment at 200oC. The prepared TiO2-coated sieves were then employed to setup a photocatalytic reactor for evaluating their abilities on the degradation of VOCs (volatile organic compounds). The UV lamp was enveloped with a cylinder TiO2-coated sieve and located in the center of the reactor. A VOCs diffusing tube was applied to yield acetone under water bath. The yielded gaseous acetone was enforced to pass through the TiO2-coated sieves and reacted by photocatalytic reaction. Both the inflow gas and off-gas were monitored by a PID (photoionization detector) sensor for calculating the treat efficiencies under various conditions. The results showed that the amorphous structure was observed on the TiO2 films after sol-gel method, whereas the crystalline anatase phase was found after annealing at 200oC. The SEM images showed that the surface morphology of TiO2 coated SS304 sieves was very similar to that of uncoated sieves, demonstrating a good uniformity and thin thickness of the sol-gel coating method derived in this work. It was observed that most volatile acetone (almost 100%) was removed after treated with the designed photocatalytic reactor under a high fed flow rate (0.5- 2.0 l/min). As compared with the control experiments (UV OFF test), the adequate photocatalytic abilities of this developed TiO2 coated sieves were demonstrated. With the advantages of high contacting area with VOCs, low headloss, durable substrate and easy maintenance, the TiO2-coated sieves possessed a high potential for applying on the photocatalytic degradation of indoor air pollutants.

Abstract: . The study combined UV/TiO2 with ultrasonic procedure to degrade azo dye wastewater of Acid Yellow 17. The effects of factors including pH value, initial concentration of dye, and quantities of TiO2, Fe (II), and Fe (III) added on the removal efficiency of azo dye Acid Yellow 17 were investigated. Experimental results revealed significant additive effect attributed to the combination of two procedures under 13-watt UV irradiation and 10-watt ultrasound. Analysis of the catalyst properties indicated no evident changes in the appearance of crystal and TiO2 catalyst by UV/TiO2 combined with ultrasonic procedure. However, the specific surface area was increased by approximately 53%. No effective formation of hydrogen peroxide (ND  1 mg/L) proved that the addition of Fe (II) and Fe (III) failed to induce the Fenton-like reaction effectively. Nevertheless, the addition of Fe ions affected significantly the initial adsorption and the degradation rate of the dye. Moreover, the treatment efficiency of Fe (III) was found to be superior to that of Fe (II) under the same concentration.

Abstract: TiO2 thin films obtained by sol-gel and dipping deposition on glass fibers substrates followed by thermal treatment was used in this works. In an attempt to understand the structure and the morphology of TiO2 sol-gel thin films, analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) are reported. Degradation of toluene under 365 nm light illumination was conducted to evaluate the photocatalytic ability of the TiO2 thin films. A special design of glass reactor allowed the UV lamp to be located in the center of the reactor. The photocatalyst reactor was then filled with TiO2 thin films/glass fibers substrates to exams the photocatalysis of toluene vapor ranged from 10 to 1,000 ppmv. Toluene depletion was sampled by gas chromatography (GC). The results showed that the photocatalytic performance of the reactor had high toluene depletion efficiency of 99.9% under 20 ppmv, and the efficiency decreased when toluene concentration were 100 and 1,000 ppmv. The improvement of the photocatalytic activity was ascribed to the fibers-based reactor provides a significantly huge surface area of the TiO2 thin films. These results will be useful and assist engineers to design photocatalyst reactors for the VOCs removal.

Abstract: In this study, the Taguchi method was used to optimize the preparation of titanium dioxide thin film reactor through modified chemical vapor deposition (CVD) method and then conversion ratio of toluene was evaluated at the optimal condition. The results indicated that optimal condition for preparation of TiO2 thin film reactor was as followings: water bath temperature of 80°C, Ti (OC3H7)4 / H2O ratio of 4, carrier gas flow rate of 1000 mL min-1, catalytic oxidation temperature of 400°C, oxidation time of 8 hrs, calcination temperature of 450°C, spraying speed of 30 rpm and furnace linear motion geared motor speed of 75 cm min-1. The conversion ratio of 56.56 ppmv toluene could be achieved up to 99.8% with the irradiation intensity of 3.76μW cm-2 at the flow rate of 300 mL min-1 after 120 minutes.