Browsing by Author "Nguyen Thi Thuy"

Now showing 1 - 4 of 4

Anodic fabrication of advanced titania nanotubes photocatalysts for photoelectrocatalysis decolorization of Orange G dye
(2016-02-01)
Juang, Yaju
;
Liu, Yijin
;
Nurhayati, Ervin
;
Nguyen Thi Thuy
;
Huang, Chihpin
Titania nanotubes (TNTs) were fabricated on Ti mesh substrates by the anodizing technique. The effects of preparation variables, such as anodizing voltage, time and calcination temperature on the textural characteristics and photocatalytic activity of TNTs were investigated. The surface morphology, crystalline phase, and chemical composition were analyzed using field emission-scanning electron microscopy and X-ray diffraction. The photo-electrochemical properties of TNTs were examined by voltammetry. The TNTs were tested as a photoanode for advanced oxidation processes, such as photocatalytic, electrocatalytic, and photoelectrocatalytic decolorization of Orange G dye. The well-arranged TNTs electrode prepared in this work showed a high photocurrent density of 101 mu A cm(-2) at an optimum length-to-diameter aspect ratio of 31.2. In dye decolorization tests, the electrochemical photocatalytic system using TNTs as the photoanode achieved total decolorization and 64% mineralization under extended reaction time. These results show that TNTs prepared by this method is greatly stable in prolonged use and suitable as a photoanode in the photocatalytic/photoelectrocatalytic treatments of dye wastewater. (C) 2015 Elsevier Ltd. All rights reserved.
Measurement of transparent Alcian blue-stainable materials in freshwater by a centrifugation-based method
(2017-02-01)
Nguyen Thi Thuy
;
Huang, Chihpin
;
Lin, Justin Chun-Te
;
環境工程研究所
;
防災與水環境研究中心
Transparent exopolymer particles (TEP) are particularly abundant in diverse aqueous environments and regarded as a main contributor to biofilm and membrane biofouling. In this study, we optimized a centrifugation- based approach to analyze Alcian blue-stainable materials (ABSM), which cover TEP and acidic polysaccharide-related substances, for reservoirs in Taiwan. Stability of the dye in terms of time and acidic conditioning was firstly monitored intensively at pH 2.5 and 4.0, with and without stirring. Absorbance of dye-reacted solutions of the reference materials ( xanthan gum) and natural ABSM sampled from reservoirs were both examined under different relative centrifugal forces (RCF). Separation efficiency of complexes generated between Alcian blue and the targeting materials under broad range of RCFs (from 1,089 to 34,957 xG) was further assessed based on particle hydrodynamic size distributions, which then provided an insight of their fates that former methods were not addressed. Our results showed centrifugation at high RCFs ( higher than 12,096 xG) was effective to separate these complexes comparing with previous studies only conducted at lower RCFs. Application of the proposed method for five freshwater samples revealed notable high concentrations of Alcian blue-stainable dissolved fraction that could be a critical factor in developing feasible antifouling strategies for membranes used in water treatment.
Temporal variation and interaction of full size spectrum Alcian blue stainable materials and water quality parameters in a reservoir
(2015-07-01)
Nguyen Thi Thuy
;
Lin, Justin Chun-Te
;
Juang, Yaju
;
Huang, Chihpin
;
環境工程研究所
This paper reports on the fate of different fractions of Alcian blue, (AB) stainable material in Pao-Shan reservoir, Taiwan, in a one-year study (2013-2014) and an intensive study during phytoplankton bloom (2014). The interactions between the fractions, including AB stained particles, particle and colloidal transparent exopolymer particles (pTEP and cTEP), dissolved acid polysaccharide (dAPS), and their relationship to other water quality parameters were analyzed. The Flow Cytometer and Microscope (FlowCAM) was for first time used to characterize AB stained particles. The results of the one-year study likely showed relationships of pTEP concentration to phytoplankton count and chlorophyll a, while in the intensive study, AB stained particles abundance and pTEP concentration were correlated neither phytoplankton count nor chlorophyll a, but strongly positively correlated with some phytoplankton species\' abundance. The difference indicates that sampling frequency and phytoplankton composition should be addressed for studying the links between AB stained fractions and phytoplankton. The interaction between different AB stained fractions further suggests that the majority of AB stained particles and pTEP would be directly generated by some phytoplankton species, whereas their abiotic generation by cTEP or dAPS may only have contributed partly to their formation. This differs from previous studies which generally posited that pTEP are mainly formed abiotically from dissolved precursors. Successful application of FlowCAM for visualization of AB stained particles recommends this technique by which particle morphologies can be conserved and morphological features of particle can be simultaneously elucidated. (C) 2015 Elsevier Ltd. All rights reserved.
Visualization and quantification of transparent exopolymer particles (TEP) in freshwater using an auto-imaging approach
(2017-07-01)
Nguyen Thi Thuy
;
Huang, Chih-Pin
;
Lin, Jr-Lin
;
環境工程研究所
;
Institute of Environmental Engineering
Most water sources are full of microscopic transparent exopolymer particles (TEP), which are currently regarded as a major initiator of biofilm formation. This study developed and applied an auto-imaging FlowCAM-based method for online observation and quantification of TEP in freshwater. Samples from reservoirs in Taiwan with a wide range of water quality were directly used to develop this methodology. Factors that potentially affect the measurement were tested. The results showed that characteristics of the particles measured instantaneously after staining samples with Alcian blue differed significantly from those measured at steady states, as a result of particle aggregation. Compared to traditional microscopic methods, this proposed method provides a simple, rapid, and less labor-intensive analysis with particle morphological conservation and a large number of particle attributes. By overcoming the limitations from the former, this technique would offer routine monitoring of these transparent particles from various freshwater sources and feed water in membrane filtration, hence facilitating the use of TEP as a critical parameter for biofouling investigation in water treatment. Application of the method for Taiwan reservoirs showed a wide variety of morphological forms of TEP and its abundance, up to 25,000 ppm.