Browsing by Author "Huang, C. P."

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Adsorption characteristics of ammonium ion onto hydrous biochars in dilute aqueous solutions
(2019-01-01)
Fan, Ruemei
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Chen, Ching-lung
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Lin, Jui-yen
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Tzeng, Jing-hua
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Huang, Chih-pin
This research aims at studying the characteristics of ammonium adsorption onto hydrous bamboo biochar. Results showed that pH played the most important role in ammonium adsorption. High ionic strength enhanced the ammonium adsorption capacity of bamboo biochar. Ammonium adsorption was exothermic and spontaneous. FTIR results showed shift, disappearance, or appearance of specific functional groups on the bamboo biochar surface. Surface precipitation and complex formation contributed to the adsorption of ammonium onto hydrous bamboo biochar. Biochar can be an effective adsorbate for ammonium removal from water. Additionally, the formation of nitrogen containing precipitates on the biochar surface, potentially, leads to the in-situ synthesis of slow-release fertilizer.
Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation
(2008)
Su, Y. C.
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Huang, C. P.
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Pan, Jill R.
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Lee, H. C.
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環境工程研究所
Recently, the membrane bioreactor ( MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub- critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub- critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules ( e. g. polysaccharides) may play an important role in membrane fouling under sub- critical flux operation.
Enhanced catalytic reduction of nitrophenols by sodium borohydride over highly recyclable Au@graphitic carbon nitride nanocomposites
(2019-01-01)
Thanh Binh Nguyen
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Huang, C. P.
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
In this study, a photochemical green synthesis using thermal exfoliation process is developed to fabricate Au@graphitic carbon nitride (g-C3N4) nanocomposite, highly recyclable and reusable, for the catalytic reduction of nitrophenols by NaBH4. Au nanoparticles (Au NPs) in the diameter of 5-15 nm are deposited onto the surface of g-C3N4 in 3-6 layers of structure. The synthesized Au@g-C3N4 nanocomposites exhibit excellent catalytic activity and stability in the reduction of nitrophenols including 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-nitrophenol, and 2,4,6-nitriophenol. The catalytic performance of Au@g-C3N4 is highly dependent on the initial nitrophenol concentration, Au loading, inorganic anions, and pH. The rate constant of 4-nitrophenol reduction over Au@g-C3N4 (2 wt%) is 26.4 times that of pure Au NP in the presence of 7 mM of NaBH4 at pH 5. Moreover, Au@g-C3N4 can be reused for at least 10 consecutive cycles without considerable loss of catalytic activity. The presence of anions (0.1 M) such as H2PO4-, SO42-, HCO3-, and NO3- decreases the rate of 4-nitrophenol reduction by a factor of 1.2-8.8; whereas there is a 1.2-time increase in rate constant upon the addition of Cl- ion. The detection of H-center dot radical adducts indicates that Au NPs adsorbs BH4- ions and forms Au-H species. The porous and conductive g-C3N4 provides large surface area for nitroarene adsorption and subsequent electron transfer from the Au-H species to 4-nitrophenol, which results in accelerating the reduction of 4-nitrophenol. Results clearly demonstrate that Au@g-C3N4 is a promising green catalyst of enormous potential for nitroaromatic reduction, which provides a new venue for tailoring Au-based nanomaterials in elucidation of a wide variety of heterogeneous catalytic reactions.
Fouling analysis of polysulfone ultrafiltration membranes used for drinking water treatment
(2011)
Zhao, B. Q.
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Huang, C. P.
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Chen, S. Y.
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Wang, D. S.
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Li, T.
Natural organic matter (NOM) plays a significant role in the fouling of ultrafiltration membranes in drinking water treatment processes. For a better understanding of the interaction between fractional components of NOM and polysulfone (PS) ultrafiltration membranes used for drinking water treatment, fouling and especially the physically irreversible fouling of natural organic matter were investigated. Resin fractionation, fluorescence excitation-emission matrix (EEM) spectroscopy, fourier transform infrared spectroscopy (FTIR), contact angle and a scanning electron microscope (SEM) were employed to identify the potential foulants. The results showed that humic acid and fulvic acid of small size were likely to permeate the membrane, while the hydrophobic fraction of humic and fulvic acid and aromatic proteins tended to be rejected and retained. Organic compounds such as proteins, humic substances, and polysaccharide-like materials, were all detected in the fouling layer. The physically irreversible fouling of the PS membrane seemed to be mainly attributed to the hydrophobic fraction of humic substances.
Graphite Supported Stainless-Steel Electrode for the Degradation of Azo Dye Orange G by Fenton Reactions: Effect of Photo-Irradiation
(2019-01-01)
Liu, Ching-Fang
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Huang, C. P.
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Juang, Yaju
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Hu, Chi-Chang
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Huang, Chihpin
An electrode, stainless steel supported on graphite, was used for the degradation of hazardous organic compounds, azo dye Orange G (OG), using the photoelectro- Fenton (PEF) process. Results showed that the applied current controlled the electrogeneration rate of both ferrous ion and hydrogen peroxide, which in turn affected the dye degradation kinetics. At an applied current density of 45Acm-2, the SS-graphite electrode yielded a molar [H2O2]/[Fe2+] ratio of 3.6, which was optimal for dye degradation. Under otherwise identical conditions, UV irradiation significantly enhanced OG degradation, i.e.,PEF is more effective than electro-Fenton (EF) process. At the optimal applied current density of 45Acm-2, or optimal molar [H2O2]/[Fe2+] of 3.6, OG decolorization and total organic carbon removal were 83% (in 3h) and 55% (in 7h), versus 75% (in 3h) and 20% (in 7h) by PEF and EF, respectively. OG degradation by both PEF and EF processes followed the pseudo first-order kinetics, which suggested the major role of OH radical in OG decolorization.
Influence of pulsed laser annealing on the optical properties of ZnO nanorods
(2012-08-01)
Lin, T. N.
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Huang, C. P.
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Shu, G. W.
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Shen, J. L.
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Hsiao, C. S.
"The effect of pulsed laser annealing (PLA) on the photoluminescence (PL) properties of ZnO nanorods was investigated. As the fluence of pulsed laser increases, the UV PL in ZnO nanorods shows a general increasing trend, except at a range of fluences from 10 to 70?mJ/cm2. It is found that the treatment with the PLA at the fluence of 70?mJ/cm2 leads to a larger improvement of crystalline properties than that with rapid thermal annealing (RTA). The relationship between PL intensity and fluence of pulsed lasers can be well explained by a combination of the deterioration in surface crystallinity and the increased donor densities after PLA."
Photocatalytic degradation of bisphenol A over a ZnFe2O4/TiO2 nanocomposite under visible light
(2019-01-01)
Thanh Binh Nguyen
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Huang, C. P.
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
A ZnFe2O4-TiO2 nanocomposite combining p-type ZnFe2O4 and n-type TiO2 was successfully fabricated. The ZnFe2O4-TiO2 nanocomposite greatly enhanced the bisphenol A (BPA) photodegradation under visible light irradiation at 465 +/- 40 nm. Loading TiO2 with 1 wt% of ZnFe2O4 produced high photocurrent and low charge transfer resistance. The photodegradation rate of BPA by ZnFe2O4-TiO2, which was highly dependent on the water chemistry including pH, anions, and humic acid, was 20.8-21.4 times higher than that of commercial TiO2 photocatalysts. Chloride and sulfate ions enhanced BPA photodegradation mostly due to the production of more radical species; whereas nitrate, dihydrogen phosphate, and bicarbonate ions decreased the photodegradation rate of BPA due to the scavenge of hydroxyl radicals. The photoactivity and recyclability of ZnFe2O4-TiO2 in lake water was also assessed. A near complete BPA removal from lake water was observed under visible light irradiation. Furthermore, >90% of photocatalytic activity toward BPA degradation was achieved in 5 cycles of continuous addition of BPA to the lake water. The BPA degradation intermediates were identified by HPLC/MS/MS and possible reaction pathways were proposed. Results clearly demonstrate the excellent visible-light-sensitive photocatalytic degradation of BPA over ZnFe2O4-TiO2 composite which has a great application potential for the decomposition of emerging contaminants in impaired waters. (c) 2018 Published by Elsevier B.V.
Photoelectrochemical degradation of dye wastewater on TiO2-coated titanium electrode prepared by electrophoretic deposition
(2016-06-13)
Liu, Ching-Fang
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Huang, C. P.
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Hu, Chi-Chang
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Juang, Yaju
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Huang, Chihpin
The degradation of azo dye Orange G (OG) on TiO2/Ti electrode was studied using a photoelectrocatalytic system. TiO2/Ti electrode was prepared by electrophoretic deposition (EPD) process. Results of surface analyses, namely, X-ray diffraction (XRD), SEM, X-ray photoelectron spectroscopy (XPS), and linear sweep voltammetry (LSV), revealed that the optimal EPD condition was a deposition potential of 180 V for 1 min and annealed at 350 degrees C. The TiO2/Ti electrode was used as photoanode and a graphite cathode for the degradation of OG. The coupling effect of photocatalytic and electrochemical oxidation processes was evaluated in terms of the decolorization of OG. The degradation of OG increased in the following increasing order: photocatalysis < electrochemical oxidation < photoelectrochemical degradation. A decolorization of 54.3% was achieved at an applied current density of 75 A cm(-2). The degradation of Orange G follows the first-order kinetics in those three treatment processes, which suggests the participation of OH radicals in the decolorization reaction. (C) 2016 Elsevier B.V. All rights reserved.
The role of fluoroaluminate complexes on the adsorption of fluoride onto hydrous alumina in aqueous solutions
(2020-03-01)
Lin, Jui-Yen
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Chen, Yung-Long
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Hong, Xin-Ya
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Huang, Chinpin
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Huang, C. P.
Activated alumina (AA) has been extensively applied in the defluorination of industrial wastewaters and groundwater. Although the dissolution of AA due to formation of fluoroaluminate complexes (AlFx3-x), especially in acidic condition, has been observed, its role on fluoride uptake by alumina has not been discussed in any previous literature, most of which consider F- as the sole adsorbed species. The present study described the effect of fluoroaluminate complexes on fluoride adsorption onto alumina. Results indicated that fluoroaluminate complexes, major fluoride species at pH < 6, were responsible for total fluoride adsorbed. Free fluoride ions were adsorbed mainly in the alkaline pH region, e.g., pH > 6. The dissolution of AA during defluorination was measured and analyzed by the thermodynamic solubility model. The surface concentration of F- and AlFx3-x were calculated considering electrostatic interactions. Characterization of fluoride-laden AA by XPS revealed that the fraction of surface Al-F species decreased with pH, which suggested the transition of the surface fluorinated species to that of free fluoride ions. The stability constants of four surface complexes, namely, AIOH-FAl2+, AlOH-F2Al+, AlOH2(+)(F)-F-, and AIOH-F-, were 10(6.88), 10(5.36), 10(2.72) and 10(2.36), respectively. Obviously fluoroaluminate complexes exhibited stronger chemical bonds with the surface hydroxy species than free fluoride. (C) 2019 Published by Elsevier Inc.
Uptake of BDE-209 on zebrafish embryos as affected by SiO2 nanoparticles
(2018-08-01)
Chao, Shu-Ju
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Huang, C. P.
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Chen, Pei-Chung
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Chang, Shih-Hsien
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Huang, Chihpin
It was hypothesized that interactions between emerging contaminants such as decabromodiphenyl ether (BDE-209) and nanoparticles (NPs) such as nano-SiO2 (nSiO(2)), can affect contaminant transport in the aquatic environment and its ecotoxicity. This study assessed the influence of nSiO(2) on the uptake of BDE-209 by zebrafish embryo. The distribution of BDE-209 and nSiO(2) on the external chorion and the internal embryo mass (i.e., dechorionated embryo) was measured. For single exposure of nSiO(2) to zebrafish embryo, separately, results showed that nSiO(2) accumulation on the chorion surface was higher than that in the dechorionated embryo. The nSiO(2) accumulation on the chorion surface was 129-200 mg-nSiO(2)/gchorion at 48 h post fertilization, hpf, of exposure time, whereas the equilibrium adsorption of nSiO(2) on the dechorionated embryo was ca. 0.42-0.54 mg-nSiO(2)/g-embryo at 6 hpf. Results showed that the formation of nSiO(2)-BDE-209 associates promoted both extracellular and intracellular uptake of BDE-209 by zebrafish embryo, thereby increasing the bioconcentration of BDE-209 on the chorion surface and in embryo. The results also revealed that the accumulation of BDE-209 on the chorion was remarkably greater than that on the dechorionated embryo at 48 hpf. The uptake of BDE-209 was 17.2 +/- 0.45 mg/g-chorion (or 86 ng-BDE-209/chorionated embryo) and 0.37 +/- 0.01 mg/g-embryo (or 18.6 ng-BDE-209/dechorionated embryo), respectively, when co-exposure of zebrafish embryos to BDE-209 and nSiO(2). Results from the SEM and EDS analysis revealed that nSiO(2) already passed through the chorion and adhered to the embryo surface/mass. (C) 2018 Elsevier Ltd. All rights reserved.