Papers by Author: Chen Yu Chang

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: 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: Advanced oxidation processes (AOPs) are potential technologies for the treatment of wastewaters containing non-easily removable organic compounds. Isopropyl alcohol (IPA) is one of the groups with high toxicity and low biodegradability and is always interested by researchers. In this study, Chemical Vapor Deposition (CVD) was used to immobilize TiO2 photocatalyst on the titanium substrate plate and extra applied electric potential on the working electrode (anode) combined with a 365 nm UV lamp for irradiating the IPA wastewater to conduct a photoelectrocatalytic reaction. The experimental results showed, during the photoelectrocatalytic reaction, the extra applied electric potential could inhibit the recombination of the electron-hole pair and raise the overall removal efficiency. However, when the potential was more than 0.5 V, it would reduce the photoelectrocatalytic effect because of the recombination of electrons and holes. Moreover, adding different electrolyte solutions enhanced the different degree of effects of IPA removal. Among the electrolyte solutions added, sodium sulfate improved the photoelectrocatalytic effect most significantly.

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.