Browsing by Author "Chiang, PC"

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A dynamic model of ozone disinfection in a bubble column with oxygen mass transfer
(2002-05-01)
Chen, YH
;
Chang, CY
;
Yu, YH
;
Chiang, PC
;
Chiu, CY
The dynamic process of disinfection with ozone in a bubble column is studied for model establishment. Bubble columns have been widely used for ozone disinfection in plants and laboratories. Ozone is produced by passing oxygen-enriched gas through an ozone generator, and introduced into the bottom of a column equipped with a gas-diffuser. There certainly exists a temporary and unsteady period before the ozone disinfection system reaches steady state. Available ozone disinfection models employed to describe dissolved ozone and surviving microorganism profiles have commonly been developed for steady state. Moreover, oxygen mass transfer has usually been neglected in previous ozone disinfection models. However, this information is desirable for the proper operation of ozone disinfection in a bubble column. Thus, the objective of this study was to model and investigate the dynamic ozone disinfection process in a bubble column with oxygen mass transfer. A dynamic axial dispersion model is proposed and was employed to predict the variation of the ozone, microorganism and oxygen concentrations along the column. The results of prediction were obtained based on the conditions of Marinas et al. (1993). E. coli was chosen as the model microorganism. The dynamic model of ozone inactivation is useful for proper prediction of the variables of an ozone disinfection system in a bubble column.
Decomposition of 2-mercaptothiazoline in aqueous solution by ozonation
(2004-07-01)
Chen, YH
;
Chang, CY
;
Chen, CC
;
Chiu, CY
;
Yu, YH
This study investigates the ozonation of 2-mercaptothiazoline (2-MT). The 2-MT is one of the important organic additives for the electroplating solution of the printed wiring board industry and has been widely used as a corrosion inhibitor in many industrial processes. It is of concern for the aquatic pollution control especially in the wastewaters. Semibatch ozonation experiments in the completely stirred tank reactor are performed under various concentrations of input ozone. The concentrations of 2-MT, sulfate, and ammonium are analyzed at specified time intervals to elucidate the decomposition of 2-MT during the ozonation. In addition, the time variation of the dissolved ozone concentration (C-ALb) is continuously monitored in the course of experiments. Total organic carbon (TOC) is chosen and measured as a mineralization index of the ozonation of 2-MT. The results indicate that the decomposition of 2-MT is efficient, while the mineralization of TOC is limited via the ozonation only. Simultaneously, the yield of sulfate with the maximum value of about 47% is characterized by the increases of TOC removal and ozone consumption. These results can provide some useful information for assessing the feasibility of the treatment of 2-MT in the aqueous solution by the ozonation. (C) 2004 Elsevier Ltd. All rights reserved.
Decomposition of 2-naphthalenesulfonate in aqueous solution by ozonation with UV radiation
(2002-09-01)
Chen, YH
;
Chang, CY
;
Huang, SF
;
Chiu, CY
;
Ji, D
This study investigates the ozonation of 2-naphthalenesulfonate (2-NS) combined With ultraviolet (UV) radiation, Naphthalenesulfonic acids are of importance as dye intermediates for the dye and textile auxiliary industries. Its derivatives, such as 2-NS. have been found in rivers and tannery effluents causing Pollution problems. Thus, the 2-NS is of concern for the aquatic pollution control especially in the surface and waste waters. Ozonation combined with UV radiation is employed for the removal of 2-NS in the aqueous solution. Semibatch ozonation experiments were proceeded under different reaction conditions to studs the effects of ozone dosage and UV radiation on the oxidation of 2-NS. The concentrations of 2-NS and sulfate are analyzed at specified time internals to elucidate the decomposition of 2-NS. In addition, values of pH and oxidation reduction potential are continuously Measured in the course of experiments. Total organic carbon is chosen as a mineralization index of the ozonation of 2-NS, The mineralization of 2-NS via the ozonation is remarkably enhanced by the UV radiation. These results can provide useful information for the proper removal of 2-NS in the aqueous solution by the ozonation with UV radiation. (C) 2002 Published by Elsevier Science Ltd.
Dynamic behavior of ozonation with pollutant in a countercurrent bubble column with oxygen mass transfer
(2003-06-01)
Chen, YH
;
Chang, CY
;
Chiu, CY
;
Yu, YH
;
Chiang, PC
The dynamic behavior of ozonation with pollutants in a countercurrent bubble column is studied for the model establishment. Bubble columns have been widely used for an ozonation system in the plants and laboratories. In addition, a countercurrent bubble column has been commonly recommended than a cocurrent one because it has a higher ozone transfer efficiency. Therefore, the investigation of this paper focuses on the countercurrent bubble column. As an ozonation process starts, the gas mixture of ozone and oxygen is introduced into the bottom of a column, and then transferred into the liquid. The pollutants in the wastewater are eliminated subsequently via oxidation by the dissolved ozone. There certainly exists a temporary and unsteady period before the ozonation system reaches steady state. However, available ozonation models employed to describe ozone and pollutant profiles have commonly been developed for steady state. The treating qualities of wastewater in the early stage of ozonation are usually not predicted, and the time required for the steady-state establishment remains to be determined. Moreover, oxygen mass transfer is usually neglected in previous ozonation models so that the increase of dissolved oxygen is uncertain. These information is desirable for the proper design and operation of ozonation system in a bubble column. Thus, the aim of this study is to model and investigate the dynamic processes of ozonation with pollutants including oxygen mass transfer. The dynamic axial dispersion model proposed is employed to predict the variation of the ozone, pollutant, and oxygen concentrations profiles. The validity of the model was demonstrated by comparing the predicted results with the experimental data. The o-cresol was chosen as the model pollutant. The temporal concentration variations of the residual o-cresol and dissolved oxygen in the effluent liquid, and the off-gas ozone in the free volume were measured accordingly. Furthermore, the variation of the enhancement factor of ozone and the amount of off-gas were predicted. Note that it usually needs 2-5 hydraulic retention times to approach steady state under the conditions of this study. Further, the effects of dimensionless system parameters on the performance of the ozonation processes are examined. As a result, the proposed dynamic model of ozonation with pollutants is useful for proper prediction of the variables of an ozonation system in a countercurrent bubble column. (C) 2003 Elsevier Science Ltd. All rights reserved.
Dynamic model of ozone contacting process with oxygen mass transfer in bubble columns
(2002-11-01)
Chen, YH
;
Chang, CY
;
Chiu, CY
;
Huang, WH
;
Yu, YH
The dynamic process of the dissolution of ozone in a countercurrent bubble column is studied for model establishment. Bubble columns have been used widely for ozone contacting in the plant and laboratory. Ozone is produced by oxygen-enriched gas through an ozone generator, and introduced into the bottom of the column equipped with the gas diffuser. The ozone contacting system proceeds for a temporary and unsteady period before reaching steady state. The available ozone dissolution models employed for the description of the dissolved ozone profiles were commonly developed for the steady state. Moreover, oxygen mass transfer is usually neglected in the preceding ozone dissolution models. However, this information is desirable for proper operation of ozone dissolution in a bubble column. Thus, the objective of this study is to model and investigate the dynamic ozone dissolution process in a bubble column with the oxygen mass transfer. The dynamic axial dispersion model proposed is employed to predict the variations of ozone and oxygen concentrations along the column, and the amount of off-gas. The validity of the model is demonstrated by comparing the predicted results with the experimental data. The dynamic model of ozone dissolution is useful and referable for proper prediction of the variables of the ozone contacting system in a bubble column.
Effect of the polyimide structure and ZnO concentration on the morphology and characteristics of polyimide/ZnO nanohybrid films
(2005-01-21)
Hsu, SC
;
Whang, WT
;
Hung, CH
;
Chiang, PC
;
Hsiao, KN
A series of polyimide/ZnO nanohybrid films with different ZnO content were prepared from a rigid pyromellitic dianhydride-4,4'-diaminodiphenyl ether (PMDA-ODA) polyimide (PI) and a flexible 3,3,4,4-benzophenonetetracarboxylic acid dianhydride-4,4'-diaminodiphenyl ether (BTDA-ODA) PI with ZnO nanoparticles (3-4 nm). Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) depict that the ZnO nanoparticles function as a physical cross-linking agent with PI through hydrogen bonding between the OH on the ZnO nanoparticles and the C=O of the imide groups. ZnO nanoparticles in the rigid PMDA-ODA matrix cause a larger percentage decrease in the coefficient of linear thermal expansion (CTE) than in the flexible BTDA-ODA matrix. The BTDA-ODA/ZnO hybrid films have two transition peaks in dynamic mechanical tan curves, but PMDA-ODA/ZnO hybrid films only have one transition peak. Thermogravimetric analysis reveals that ZnO decreases the thermal degradation temperature (T-d) in both hybrid films, but less so in PMDA-ODA/ZnO films. Trans-mission electron microscopy (TEM) images reveal that the rigid matrix induces larger particle size (30-40 nm) compared to the flexible matrix (10-15 nm).
Effects of titania content and plasma treatment on the interfacial adhesion mechanism of nano titania-hybridized polyimide and copper system
(2004-06-03)
Chiang, PC
;
Whang, WT
;
Wu, SC
;
Chuang, KR
;
材料科學與工程學系
Nano-titania (TiO2) incorporated into polyimide (PI) matrix can significantly enhance the adhesion strength for PI/TiO2 hybrid film and copper system. Surface modifications by various plasma treatments (Ar, Ar/N-2 and Ar/O-2) were also applied in this study to improve the adhesion strength. The Ar/N2 plasma treatment is regarded as the more effective way in promoting the adhesion strength. The maximum adhesion value of 9.53 N/cm was obtained for the PI/TiO2-1 wt% hybrid film with Ar/N-2 plasma treatment. It is enhanced about 10 times as large as pristine PI. Furthermore, by Ar/O-2 plasma treatment, a weak boundary of copper oxide was formed at the interlayer between PI/TiO2 hybrid film and copper which decreases the adhesion strength. The effects of plasma treatment and content of nanosized TiO2 on the adhesion strength between PI/TiO2 hybrid film and copper system were studied. Atomic force microscope and contact angle analyses were used to measure the changes in surface morphology and surface energy as a result of plasma treatment. Besides, the interfacial states of peeled-off polymer side and copper side were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Based on the result of XPS spectra, the peeled-off failure mode between PI/TiO2 hybrid film and copper was proposed in this study. (C) 2004 Elsevier Ltd. All rights reserved.
Kinetics of decomposition of polyethylene glycol in electroplating solution by ozonation with UV radiation
(2001-10-01)
Chang, CY
;
Chen, YH
;
Li, H
;
Chiu, CY
;
Yu, YH
The kinetics of the ozonation of polyethylene glycol (PEG) with ultraviolet (UV) radiation in the acid-based electroplating solution of the printed wiring board industry is studied. The substrate prescription of a typical electroplating solution is with pH of 0. 18-0.42, [CuSO4 . 5H(2)O] of 200 g/L, [H2SO4] of 60 g/L, and [Cl-] of 0.03 g/L. Certainly, the discarded electroplating solution is hard to treat with the common chemical and biological processes because of its acidic and metallic compositions. In addition, it contains valuable substances suitable for recovery and reutilization. One of the most important processes for reviving it is to remove the aged organic additives such as PEG. A two-step reaction mechanism in terms of ozone A and total organic carbon is proposed to express the reaction kinetics of PEG ozonation with UV radiation with intensity [I-uv]. The initial concentration of PEG is 30 mg/L, according to the recipe of a typical electroplating solution, which is equivalent to total organic carbon of 16.3 mg/L. The reaction rate r expressions of the concentrations of the liquid phase ozone C-ALb, PEG C-BLb, and intermediates C-ILb are r(A) (=dC(ALb)/dt) = -(k(Am) + k(t)[I-uv)C-ALb (k(R1) + k(RI1)[I-uv])CALbCBLb - (k(R2) + k(RI2)[I-uv])CALbCILb, r(B) (=dC(BLb)/dt) = -(k(R1) + k(RI1)[I-uv])CALbCBLb, r(int) (=dC(ILb)/dt) (k(R1) + k(RI1)[I-uv])CALbCBLb - (k(R2) + k(RI2)[I-uv])CALbCILb, with k(Am) = 0.0036 s(-1), k(1) = 4.654 X 10(-5)s(-1)/(Wm(-2)), k(R1) = 13.525 M(-1)s(-1), k(R2) = 0.751 M(-1)s(-1), k(RI1) = 0.683 M(-1)s(-1)/(Wm(-2)), and k(RI2) = 0.042 M(-1)s(-1)/(Wm(-2)). These reaction kinetic expressions are useful and referable for the proper design of an ozonation system with UV radiation for the treatment of PEG in the printed wiring board electroplating solution.
Physical and mechanical properties of polyimide/titania hybrid films
(2004-01-30)
Chiang, PC
;
Whang, WT
;
Tsai, MH
;
Wu, SC
;
材料科學與工程學系
Titania-containing polyimide (PI) hybrid films with homogeneous and flexible properties have been fabricated via sol-gel process. Various contents of titania are added to three different PI systems by using acetylacetone to reduce the reaction rate and to prohibit gelation. The thermal, electrical and mechanical properties of the hybrid films will be measured and compared to pure PI. Results indicate that the metal-containing PI possesses lower thermal expansion and resistivity than pure PI. Incorporation of small amount of titania enhances mechanical properties of the hybrid films at both low and elevated temperature. The relationship between the effect of titania concentration, structure and properties will also be discussed. (C) 2003 Elsevier B.V. All rights reserved.
Self-organized supramolecular wires
(2003)
Wu, CY
;
Sue, CH
;
Chiang, PC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this work, we immobilized a kind of supramolecules, the calixarenes, on the surface of a silicon wafer. Calixarenes can act as excellent hosts for many molecular guests. Based on the unique property, this work tries to explore possible applications of this material in molecular electronics, especially the immobilization of molecular devices and the measurement of molecular wires.
Synthesis and characteristics of polyimide/siloxane hybrid films for reliability adhesion
(2006-02-24)
Tsai, MH
;
Chiang, PC
;
Whang, WT
;
Ko, CJ
;
Huang, SL
Polyimide/siloxane (PISi) hybrid films from 2,2'-bis[4-(3-aminodiphenoxy)phenyl]sulfone (in-BAPS), 3,3'-oxydiphthatic anhydride (ODPA) and p-aminopropyltrimethoxysilane (APrTS) have been successfully fabricated by an in-situ sol-gel process. The APrTS is used to introduce siloxane structure and to be the end-capped agent to control the polymer block chain length in the range of 5000-20000 g/mol. The network structure of the PISi hybrid film is formed through the hydrolysis and condensation reactions. The PISi hybrid films with various polyimide block chain lengths are characterized with regard to the structure effect, mechanical properties, adhesion strength, adhesive melting flow and thermal stability. The result indicates that the more APrTS is contained, the shorter of the polyimide block chain length is formed and thus the lower inherent viscosity of APrTS-PAA is obtained. It is also suggested that the cross-linked density of the PISi hybrid film increases with the increase in the amount of APrTS. The network structure of the hybrid film reinforces the pure PI and makes the coefficient of thermal expansion (CTE) as well as adhesive melting flow decrease. Based on the dynamic mechanical analyses (DMA), the hybrid film with higher cross-linked density possesses superior mechanical property at elevated temperature. In addition, the introduction of APrTS causes an increase in thermal stability due to the network structure of hybrid film and the filler effect of the siloxane. (c) 2005 Elsevier B.V. All rights reserved.
The synthesis and morphology characteristic study of BAO-ODPA polyimide/TiO2 nano hybrid films
(2003-04-01)
Chiang, PC
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Hybrid nanocomposite films of titanium dioxide (TiO2) in polyimide (PI) from 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (BAO) and 4,4'-1-oxydiphthalic anhydride (ODPA) have been successfully fabricated by an in situ sol-gel process. These nanocomposite films exhibit fair good optical transparency up to 40 wt% of TiO2 Content. X-ray diffraction spectroscopy shows three sharp peaks in pure BAO-ODPA PI. It results from the intermolecular regularity. However, the intermolecular regularity in the hybrid film is disrupted by the introduction of TiO2 nanoparticles with no sharp peak in XRD spectra. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results confirm the formation of TiO2 particles in PI matrix. The surface Ti content is much lower than the theoretical bulk content in all hybrid films. The ratio of the former to the latter increases with the TiO2 content and levels off at TiO2 wt% greater than or equal to 20. Transmission electron microscope (TEM) images show that the TiO2 phase is well dispersed in the polymer matrix. The size of the TiO2 phase increases from 10 to 40 nm when the TiO2 content is 5-30 wt%, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.