Publications (37)88.88 Total impact
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Article: Effects of NH₄⁺ on Ce(IV) electro-regeneration in simulated and real spent TFT-LCD Cr-etching solutions.
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ABSTRACT: This investigation studies the electro-regeneration of Ce(IV) from Ce(III) in 4 M HNO(3) in the presence/absence of NH(4)(+) and real spent thin-film transistor liquid-crystal display (TFT-LCD) Cr-etching solutions. On Pt, at 2 A and 70 °C for 100 min, the Ce(IV) yield and apparent rate constant of Ce(III) oxidation in 4 M HNO(3) without NH(4)(+) were 100% and 5.54 × 10(-4) s(-1), respectively (and the activation energy was 13.1 kJ mol(-1)). Cyclic voltammetric and electrolytic measurements consistently support the noticeable inhibition by NH(4)(+) of Ce(III) oxidation and lowering of the Ce(IV) yield, respectively. The apparent diffusion coefficients for 0.2 and 0.02 M Ce(III) oxidation in 4 M HNO(3) that contained 0-0.6 M NH(4)(+) were (0.38-0.25) × 10(-5) and (1.6-0.9) × 10(-5) cm(2) s(-1), respectively. Because of combined effects of NH(4)(+) and anion impurities, the 100 min Ce(IV) yield of a real spent TFT-LCD Cr-etching solution (with [NH(4)(+)]/[Ce(III)] = 0.74 M/0.39 M) was 82%, lower than that of 4 M HNO(3) without NH(4)(+), but higher than those of 4 M HNO(3) that contained anion impurities with/without 0.4 M NH(4)(+).Journal of Environmental Management 04/2012; 104:85-90. · 3.24 Impact Factor -
Article: Characteristics of particulate emissions from a diesel generator fueled with varying blends of biodiesel and fossil diesel.
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ABSTRACT: This study investigated the particulate matter (PM), particle-bound carbons, and polycyclic aromatic hydrocarbons (PAHs) emitted from a diesel-engine generator fuelled with blends of pure fossil diesel oil (D100) and varying percentages of waste-edible-oil biodiesel (W10, 10 vol %; W20, 20 vol %; W30, 30 vol %; and W50, 50 vol %) under generator loads of 0, 1.5, and 3 kW. On average, the PM emission factors of all blends was 30.5 % (range, 13.7-52.3 %) lower than that of D100 under the tested loads. Substituting pure fossil diesel oil with varying percentages of waste-edible-oil biodiesel reduced emissions of particle-bound total carbon (TC) and elemental carbon (EC). The W20 blend had the lowest particle-bound organic carbon (OC) emissions. Notably, W10, W20, and W30 also had lower Total-PAH emissions and lower total equivalent toxicity (Total-BaP(eq)) compared to D100. Additionally, the brake-specific fuel consumption of the generator correlated positively with the ratio of waste-edible-oil biodiesel to pure fossil diesel. However, generator energy efficiency correlated negatively with the ratio of waste-edible-oil biodiesel to pure fossil diesel.Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2011; 46(2):204-13. -
Article: Effect of traffic loading on particle-bound water-soluble ions and carbons collected near a busy road and at an urban site.
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ABSTRACT: This study examines size-resolved particle-bound water-soluble ions and carbons (element carbon (EC) and organic carbon (OC)) collected near a busy road and at an urban site. The traffic-related fine and coarse particles were collected using two manual dichotomous samplers (Dichots) equipped with Quartz filters. The PM(2.5)/PM(2.5-10) value during rush hour (3.57) exceeded that during slack time (2.72). During weekdays and weekends, although the roadside PM(2.5) concentration correlated well with traffic flow (R(2)= 0.91 and 0.81, respectively), the roadside PM(2.5-10) concentration did not. The lowest second aerosol concentrations were observed from 19:00 to 21:00 during weekdays and weekends. The average content of total water-soluble ions in PM(2.5) was 30.7% and 35.7% for weekday and weekend samples, respectively (a total average of 33.2%). In PM(2.5), the content of NO(3)(-) (8.95-11.0%) exceeded that of SO(4)(2-) (7.08-8.10%) at the roadside site. Conversely, the content of PM(2.5)-bound SO(4)(2-) was higher than that of PM(2.5)-bound NO(3)(-) at the urban site. The mean content of PM(2.5)-bound TC was 35.8%, while that of PM(2.5-10)-bound TC was 15.9%. Moreover, the R(2) values of traffic flow versus PM(2.5)-bound EC concentration on weekdays and weekends were 0.89 and 0.56, respectively, and were 0.82 and 0.38, respectively, for those of traffic flow versus PM(2.5)-bound OC concentration.Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 12/2010; 45(14):1839-49. -
Article: Determination of levels of persistent organic pollutants (PCDD/Fs, PBDD/Fs, PBDEs, PCBs, and PBBs) in atmosphere near a municipal solid waste incinerator.
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ABSTRACT: This work develops a comprehensive approach for quantitatively analyzing polychlorinated and polybrominated dibenzo-p-dioxins (PCDDs/PBDDs), dibenzofurans (PCDFs/PBDFs), biphenyls (PCBs/PBBs) and diphenyl ethers (PBDEs). This technique, based on multiple (silica, alumina, and active carbon) columns, can be applied to prepare samples for determining the five group compounds based on high-resolution gas chromatography/high-resolution mass spectrometry. The method was also validated by analyses of blank and spiked samples. In the sampled air, the mean PCDD/F, PCB, PBDD/F, PBDE, and PBB concentrations were 59.6 fg WHO-TEQ Nm(-3), 6.74 fg WHO-TEQ Nm(-3), 12.2 fg WHO-TEQ Nm(-3), 52100 fg Nm(-3), and 341 fg Nm(-3), respectively. The WHO-TEQ of dioxin-like PCB and PBDD/Fs counted for 8.9% and 16% of total TEQ (summed over PCDD/Fs, PBDD/Fs, and dioxin-like PCBs), respectively, suggesting that the atmospheric concentrations of dioxin and dioxin-like compounds should be regulated together because of the persistence and toxicity of PBDD/Fs and dioxin-like PCBs.Chemosphere 08/2010; 80(10):1220-6. · 3.21 Impact Factor -
Article: PM, carbon, and PAH emissions from a diesel generator fuelled with soy-biodiesel blends.
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ABSTRACT: Biodiesels have received increasing attention as alternative fuels for diesel engines and generators. This study investigates the emissions of particulate matter (PM), total carbon (TC), e.g., organic/elemental carbons, and polycyclic aromatic hydrocarbons (PAHs) from a diesel generator fuelled with soy-biodiesel blends. Among the tested diesel blends (B0, B10 (10 vol% soy-biodiesel), B20, and B50), B20 exhibited the lowest PM emission concentration despite the loads (except the 5 kW case), whereas B10 displayed lower PM emission factors when operating at 0 and 10 kW than the other fuel blends. The emission concentrations or factors of EC, OC, and TC were the lowest when B10 or B20 was used regardless of the loading. Under all tested loads, the average concentrations of total-PAHs emitted from the generator using the B10 and B20 were lower (by 38% and 28%, respectively) than those using pure petroleum diesel fuel (B0), while the emission factors of total-PAHs decreased with an increasing ratio of biodiesel to premium diesel. With an increasing loading, although the brake specific fuel consumption decreased, the energy efficiency increased despite the bio/petroleum diesel ratio. Therefore, soy-biodiesel is promising for use as an alternative fuel for diesel generators to increase energy efficiency and reduce the PM, carbon, and PAH emissions.Journal of hazardous materials 03/2010; 179(1-3):237-43. · 4.14 Impact Factor -
Article: Characterization of Persistent Organic Pollutants in Ash Collected from Different Facilities of a Municipal Solid Waste Incinerator
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ABSTRACT: This study investigated five persistent organic pollutants (polychlorinated and polybrominated dibenzo-p-dioxins (PCDDs/PBDDs), dibenzofurans (PCDFs/PBDFs), biphenyls (PCBs/PBBs), and diphenyl ethers (PBDEs)) in ash collected from several units (super heater (SH), heat economizer (HE), semi-dryer absorber (SDA), bag-house filter (BF), and fly ash pit (FAP), and bottom ash (BA) discharger) of a large-scale municipal solid waste incinerator (MSWI). Data on levels and emission factors of the five target compounds in the different units of the MSWI were first reported. The PCDD/Fs were found in high content in the HE, mainly because of the operating temperature range (250–400°C) which is favorable for PCDD/F formation through de novo synthesis. High concentrations PCBs and PBBs were detected in the BF. The highest concentrations of PBDD/Fs and PBDEs were observed in the BA. A significant correlation existed between content of PCDD/F and PCB in individual ash and corresponding operating temperature, while the content of ash-bound PBDD/Fs and PBDEs chiefly related to feeding wastes that contained brominated flame retardants. The emission of the five pollutants in the MSWI was primarily from fly ash. Further treatment is necessary for ash collected from the HE and BF because the ash had total-PCDD/F content exceeding the regulation limit (1 ng I-TEQ/g) in Taiwan.Copyright © Taiwan Association for Aerosol Research. 01/2010; 10:391-402. -
Article: Emissions of Polychlorinated Dibenzo-p-dioxin and Polychlorinated Dibenzofuran from Motorcycles
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ABSTRACT: This study presents the first investigation of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emission from (six 2-stroke and six 4-stroke engine) motorcycles using chassis dynamometer tests. Effects of engine type and lubricant renewal on PCDD/F emission were also evaluated. The mean total PCDD/F emission concentration of tested motorcycles was 1.06 ng/Nm 3 , with a corresponding mean total PCDD/F I-TEQ of 0.0671 ng I-TEQ/Nm 3 . The mean PCDD/F emission concentration of 2-stroke engine motorcycles (1.17 ng/Nm 3 , 0.0727 ng I-TEQ/Nm 3) was more than that (0.912 ng/Nm 3 , 0.0534 ng I-TEQ/Nm 3) of 4-stroke engine motorcycles. The PCDD/F emission factors of motorcycles were comparable to those of some types of vehicles, although the tested motorcycles equipped with cylinders much smaller than those of vehicles. The dominant PCDD/F congeners of 2-stroke and 4-stroke motorcycles in emission priority were OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF, accounting for 37%, 15%, 10% and 9% of the total PCDD/F emission, respectively. The reductions of PCDD/F and I-TEQ emissions after lubricant renewal of the 4-stroke motorcycles were 26%–45% and 41%–63%, respectively.Copyright © Taiwan Association for Aerosol Research. 01/2010; 10:533-539. -
Article: Gas/Particle Partitioning of Dioxins in Exhaust Gases from Automobiles
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ABSTRACT: This study investigates distributions of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) congeners in the exhaust gases of gasoline-and diesel-fueled vehicles. 6 sport utility vehicles (SUVs), 6 diesel passenger vehicles (DPVs), and 3 heavy duty diesel vehicle (HDDV) were examined using chassis dynamometer tests for measuring vehicular dioxin emissions. The mean PCDD/F I-TEQ emission factors were 0.101, 0.0688 and 0.912 ng I-TEQ/km for the SUVs, DPVs and HDDV, respectively. Highly chlorinated congeners dominated both gaseous and particulate phase PCDD/Fs. The major contributors of gas-phase PCDD/F I-TEQ for the SUVs, DPVs, and HDDV were 2,3,4,7,8-PeCDF, 2,3,7,8-TeCDD, and 2,3,4,7,8-PeCDF, respectively; however, 2,3,4,7,8-PeCDF was the major contributor in particulate-phase PCDD/F I-TEQ of these vehicles. The particulate-phase PCDD/Fs was responsible for 78.0, 90.3 and 71.1% of total PCDD/Fs for the SUVs, DPVs, and HDDV, respectively. Therefore, the control of particulate matter is more critical than that of gaseous pollutants for reducing PCDD/F emissions from automobiles.Copyright © Taiwan Association for Aerosol Research. 01/2010; 10:489-496. -
Article: Electro-Regeneration of Ce(IV) in Simulated Spent Cr-Etching Solutions Containing Abundant Ce(III)
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ABSTRACT: This study investigated the effects of the initial Ce(III) concentration, nitric acid concentration, anion impurity, and cell device on Ce(IV) regeneration in simulated spent Cr-etching solutions from thin-film transistor liquid crystal display manufacture. Increasing (electrolyte) concentration (0.5–4 M) favored 0.2 M Ce(III) electro-oxidation, Ce(III) diffusion , and internal cell resistance reduction. The amount of Ce(IV) regenerated from Ce(III) electro-oxidation and the current efficiency (CE) at electrolysis on Pt increased with increasing initial Ce(III) concentration in 4 M without impurities in a divided cell with an anion-exchange (AMI-7001) separator. Both Ce(IV) yield and CE were lowered in the copresence of multiple impurities, and the adverse influence of a single anion impurity on the Ce(IV) yield and CE was in the order . The apparent rate constant of Ce(III) oxidation without impurity was approximately fourfold that with multiple impurities; nevertheless, the two cases exhibited similar Ce(IV) yields or CEs at electrolysis for 300 min. For the Ce(IV) regeneration, the divided cell was superior to an undivided cell in the absence/presence of multiple impurities, and the AMI-7001 was better than a cation-exchange separator (CMI-7000).Journal of The Electrochemical Society. 11/2009; 156(12):E192-E198. -
Article: Characteritization of, and health risks from, polychlorinated dibenzo-p-dioxins/dibenzofurans from incense burned in a temple.
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ABSTRACT: Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) may cause adverse health effects. However, PCDD/F emissions from burning incense in temples have rarely been addressed. This study investigates PCDD/F emissions from burning incense in a temple. The mean total PCDD/F concentrations were 72.4-82.2 pg Nm(-3) at two indoor sites; their corresponding mean total PCDD/Fs I-TEQ concentrations (0.24-0.27 pg I-TEQ Nm(-3)) were approximately 11 times that at a background location. In air samples collected from burning incense, OCDFs accounted for approximately 90% of total PCDD/Fs at the two indoor sites and an outdoor site near the temple, while the major PCDD/Fs in incense ash were PCDDs. The total PCDD/F content and toxic equivalent value of incense ash were 617 pg g(-1) and 1.55 pg I-TEQ g(-1), respectively. At the three sites inside/outside the temple, the air and ash samples contained the same four primary PCDD/Fs-OCDD, 1,2,3,4,6,7,8-HpCDD, OCDF and 1,2,3,4,6,7,8-HpCDF. The Cl- emission factor, which is related to the PCDD/F formation, from burning incense was 0.454 mg g(-1). The resultant lifetime average daily dose and cancer risk for temple workers were 0.00964 pg I-TEQ day(-1) kg(-1) and 9.64 x 10(-6), respectively, approximately 2 times that for residents near the temple (0.00489 pg I-TEQ day(-1) kg(-1) and 4.89 x 10(-6), respectively). We suggest that the chlorine content in incense must be regulated, and the high risk of PCDD/F exposure from burning incense for temple workers and visitors should be of concern.Science of The Total Environment 07/2009; 407(17):4870-5. · 3.29 Impact Factor -
Article: Nafion-117 Behavior during Cation Separation from Spent Chromium Plating Solutions
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ABSTRACT: This study investigated the behavior of Nafion-117 ion-exchange membranes that are commonly used as the separator in electrolytic regeneration of spent chromium plating solutions. In the co-presence of Cu2+, Ni2+, and Fe3+ impurities (0.01−0.1 M) in 0.5−2.0 M H2CrO4, the exchange equivalents of Ni2+ by Nafion-117 was double that of Cu2+ (0.02 mmol of H+/(g of Nafion)) but smaller than that (0.03−0.15 mmol of H+/(g of Nafion)) of Fe3+, exhibiting the order Fe3+ ≥ Ni2+ ≥ Cu2+ in Nafion affinity. The water content (41%) of a Nafion-117 membrane soaked in 2 M H2CrO4 was greater than those (35−38%) in the contaminated 2 M chromic acid solutions, whereas the porosity (0.24) of the former was smaller than those (0.29−0.37) of the latter. For the Nafion-117 in 2 M chromic acid solutions with/without cation impurities, (1) the tortuosity coefficient of Fe3+ was about 1.8 times that of Cu2+ or Ni2+, (2) the calculated pore radius was 3.2 nm for a multiimpurity case (0.1 M Cu(II), Fe(III), Ni(II), and Cr(III) each) based on the Gierke’s model, and (3) the cation impurities did not significantly influence the numbers of water molecules in Nafion clusters. The Nafion-117 withstood the pH < 0 environment with only minor rotation in the fluorocarbon backbone due to accommodation of anionic Cr(VI) within clusters.06/2009; -
Article: Regeneration of Ce(IV) in simulated spent Cr-etching solutions using an undivided cell.
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ABSTRACT: This study investigated regeneration of Ce(IV) from Ce(III) oxidation at 0.05-0.5Acm(-2) in 4M HNO(3) with/without anion impurities (SO(4)(2-) (0.01-0.2M), Cl(-) (0.01-0.08M), and/or Cr(2)O(7)(2-) (0.005-0.016M)) in an undivided cell. Both Ce(IV) yield and current efficiency (CE) were significantly lower in 0.1M than in 1-4M HNO(3) and different on anode materials (in order Pt>IrO(2)/Ti>glassy carbon). The apparent rate constants for Ce(III) oxidation on the Pt anode (k(1)) and for Ce(IV) reduction on a stainless steel cathode (k(2)) were (0.40-1.80)x10(-4) and (0.08-1.01)x10(-4)s(-1), respectively, corresponding to the apparent mass transfer coefficients of (2.0-9.0)x10(-3) and (0.4-5.1)x10(-3)cms(-1), respectively. For Ce(III) oxidation at 0.3Acm(-2) in 4M HNO(3) containing multi-impurity (0.025M SO(4)(2-)+0.08M Cl(-)+0.016M Cr(2)O(7)(2-)), the k(1) was lowered by one order of magnitude although the k(2) remained unchanged, and both Ce(IV) yield and CE were reduced by approximately 89%. The decrease of Ce(IV) yield and CE by the uni-impurity was in order Cl(-)>Cr(2)O(7)(2-)>SO(4)(2-). The obtained parameters are useful to design undivided batch reactors for the Ce(IV) electro-regeneration in spent Cr-etching solutions.Journal of hazardous materials 06/2009; 171(1-3):755-60. · 4.14 Impact Factor -
Article: Effect of Al2O3 mole fraction and cooling method on vitrification of an artificial hazardous material. Part 2: encapsulation of metals and resistance to acid.
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ABSTRACT: This study investigated the encapsulation of metals in vitrified slags using a sequential extraction procedure and how Al ions and slag structure affected the encapsulation of heavy metals. It is found that the substitution of Al ions for Si ions weakened the encapsulation of the glass matrix due to the relatively weaker single bond strength of Al-O. In addition, the substitution also governed the phase distribution of metals that tended to stay slags. In comparison to air cooled slags, water quenched slags were more amorphous and offered relatively better encapsulation of metals. These findings were also supported by the SEM observation and XRD analysis. Although Al(2)O(3) may connect the non-bridging oxygen and polymerize the slag structure, the excess addition of Al(2)O(3) reduced the metal encapsulation and acid resistance of slags.Journal of hazardous materials 05/2009; 169(1-3):635-42. · 4.14 Impact Factor -
Article: Effect of Al2O3 mole fraction and cooling method on vitrification of an artificial hazardous material. Part 1: variation of crystalline phases and slag structures.
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ABSTRACT: This study investigated how Al ions affect slag structure. During vitrification, pure Al(2)O(3), CaO, and SiO(2) served as the encapsulation phases with the use of Al mol% as an operating parameter. All specimens with the same basicity (mass ratio of CaO to SiO(2)) of 2/3 were vitrified at 1400 degrees C and cooled by air cooling or water quenching. XRD was used to measure the volume fractions of crystalline and amorphous phases. In a non-Al environment, CaSiO(3) was formed in air-cooled and water-quenched slags. With the addition of Al(2)O(3), no crystalline phases were observed in water-quenched slags. With the increase of Al mol% in specimens, the Al ions in air-cooled slags initially acted as an intermediate linking one tetrahedron chain to another and reducing the amount of crystalline phase, then behaved as a network former making the slags amorphous, and finally replaced Si ions in silicate frames to generate a large amount of CaAl(2)Si(2)O(8). Air cooling improved the formation of crystallize structures with more leachable metal ions. A highly crystallized Al-framed structure is not suitable for encapsulating hazardous metals in vitrified slags.Journal of hazardous materials 05/2009; 169(1-3):626-34. · 4.14 Impact Factor -
Article: Characterization of polychlorinated dibenzo-p-dioxin/dibenzofuran emissions from joss paper burned in a furnace with air pollution control devices.
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ABSTRACT: Burning joss paper, a common practice in temples in some Asian countries, can release toxic pollutants. This study investigated polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) emissions and profiles from burning joss paper in a temple furnace connected to two wet scrubbers. The mean total PCDD/F content and corresponding toxic equivalent quantity (TEQ) in joss paper were 193 ng kg(-1) and 0.645 ng I-TEQ kg(-1), respectively, whereas those in bottom ash from burned joss paper were 18.5 ng kg(-1) and 1.92 ng I-TEQ kg(-1), respectively. The wet scrubbers decreased individual PCDD/F emissions by 26.7-71.0% and those of total PCDD/Fs and I-TEQ by 47.2% and 66.0%, respectively. The total PCDD/F TEQ emission factors before and after the wet scrubbers were 8.14 and 3.42 microg I-TEQ ton-feedstock(-1), respectively. The estimated total PCDD/F and corresponding TEQ emissions were 5.29 g year(-1) and 0.462 g I-TEQ year(-1), respectively, in Taiwan. Burning joss paper in temple furnaces is a significant source of PCDD/F emissions.Science of The Total Environment 03/2009; 407(10):3290-4. · 3.29 Impact Factor -
Article: Metal recovery from spent hydrodesulfurization catalysts using a combined acid-leaching and electrolysis process.
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ABSTRACT: This study focuses on recovering valuable metals from spent hydrodesulfurization (HDS) catalysts using a combined acid-leaching and fluidized-bed electrolysis process. The electrolytic cell was equipped with a glass bead medium, an iridium oxide mesh anode, and a stainless steel plate cathode. An acid solution consisting of concentrated HNO3/H2SO4/HCl with a volume ratio of 2:1:1 was found to be better than the other tested solution (HNO3/H2SO4=1:1) to leach the metals. For the three-acid mixture, the best solid/liquid ratio and leaching time were 40 g/L and 1 h, respectively, at 70 degrees C; under this condition, the leaching yields of target metals (Mo, Ni, and V) in the 1st stage of leaching reached 90, 99, and 99%, respectively, much higher than those in the 2nd/3rd/4th stages. When this acid leachate was electrolyzed for 2 h at 2 A constant current (current density=approximately 35.7 mA/cm2), a stable cell voltage of 5 V was observed. The electrolytic recoveries of Mo, Ni, and V were approximately 15, 61, and 66%, respectively, but extending the electrolysis time from 2 to 4 h did not increase the recoveries. For this operation, the total recoveries (leaching yieldxelectrolytic recovery) of Mo, Ni, and V were approximately 14, 60, and 65%, respectively.Journal of Hazardous Materials 07/2008; 154(1-3):588-94. · 4.17 Impact Factor -
Article: PAHs, PAH-induced carcinogenic potency, and particle-extract-Induced cytotoxicity of traffic-related nano/ultrafine particles.
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ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) bound in nano/ ultrafine particles from vehicle emissions may cause adverse health effects. However, little is known about the characteristics of the nanoparticle-bound PAHs and the PAH-associated carcinogenic potency/cytotoxicity; therefore, traffic-related nano/ultrafine particles were collected in this study using a microorifice uniform deposition impactor(MOUDI) and a nano-MOUDI. For PM0.056--18, the difference in size-distribution of particulate total-PAHs between non-after-rain and after-rain samples was statistically significant at alpha = 0.05; however, this difference was not significant for PM0.01--0.056. The PAH correlation between PM0.01--0.1 and PM0.1--1.8 was lower for the after-rain samples than forthe non-after-rain samples. The average particulate total-PAHs in five samplings displayed a trimodal distribution with a major peak in the Aitken mode (0.032--0.056 microm). About half of the particulate total-PAHs were in the ultrafine size range. The BaPeq sums of BaP, IND, and DBA (with toxic equivalence factors > or = 0.1) accounted for approximately 90% of the total-BaPeq in the nano/ultrafine particles, although these three compounds contributed little to the mass of the sampled particles. The mean content of the particle-bound total-PAHs/-BaPeqs and the PAH/BaPeq-derived carcinogenic potency followed the order nano > ultrafine > fine > coarse. For a sunny day sample, the cytotoxicity of particle extracts (using 1:1 (v/v) n-hexane/dichloromethane) was significantly higher (p < 0.05) for the nano (particularly the 10-18 nm)/ultrafine particles than for the coarser particles and bleomycin. Therefore, traffic-related nano and ultrafine particles are possibly cytotoxic.Environmental Science and Technology 06/2008; 42(11):4229-35. · 5.23 Impact Factor -
Article: Anion effects on the electrochemical regeneration of Ce(IV) in nitric acid used for etching chromium.
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ABSTRACT: The anion impurities such as SO4(2-), Cl(-), and Cr2O7(2-) commonly present in the spent (hazardous) Cr-etch solutions from color filter manufacturing processes may influence the solutions' regeneration by the electrooxidation of Ce(III) to Ce(IV). This study, therefore, investigated the effects of these anions on Ce(III)/Ce(IV) redox reactions at glassy carbon in HNO3. In cyclic voltammetric tests, the presence of SO4(2-) decreased the formal potential but increased the peak potential separation (Delta Ep) of Ce(III)/Ce(IV) couple, and lowered the peak current for Ce(IV) reduction whereas Cl(-) did not change the formal potential and Delta Ep, but the peaks for Cl(-) and Ce(III) oxidation partially overlapped. Cr2O7(2-) slightly lowered the peak current for Ce(III) oxidation but significantly decreased that for Ce(IV) reduction. The Tafel slope for Ce(III) oxidation was approximately 65mVdecade(-1) in the absence of anion impurities. Increasing SO4(2-), Cl(-), or Cr2O7(2-) in solution raised the Tafel slope. The Ce(III)/Ce(IV) equilibrium potential decreased with the increase of SO4(2-) or Cl(-) but was hardly influenced by Cr2O7(2-) addition. These observations from individual anion species together well explained the anions' co-effect (kinetic hindrance) on the Ce(III) oxidation in HNO3, revealing that these anions are unfavorable for the electrooxidation of Ce(III) in the spent Cr-etch solutions.Journal of Hazardous Materials 05/2008; 152(3):922-8. · 4.17 Impact Factor -
Article: Reaction efficiencies and rate constants for the goethite-catalyzed Fenton-like reaction of NAPL-form aromatic hydrocarbons and chloroethylenes.
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ABSTRACT: The contaminants present as nonaqueous phase liquids (NAPLs) in the subsurface are long-term sources for groundwater pollution. Fenton-like reaction catalyzed by natural iron oxides such as goethite in soils is one of the feasible in situ chemical reactions used to remediate contaminated sites. This research evaluated the Fenton-like reaction of five chlorinated ethylenes and three aromatic hydrocarbons using goethite as the catalyst. The reaction efficiencies and rate constants of these compounds in NAPL and dissolved forms were compared. The content of goethite used in batch experiments was in the range similar to those found in subsurfaces. Low H2O2 concentrations (0.05 and 0.1%) were tested in order to represent the low oxidant concentration in the outer region of treatment zone. The results showed that at the tested goethite and H2O2 ranges, the majority of contaminants were removed in the first 120 s. When aromatics and chloroethylenes were present as NAPLs, their removal efficiencies and reaction constants decreased. The removal efficiencies of 0.02 mmol NAPL contaminants were 26-70% less than those of the dissolved. The measured rate constants were in the order of 10(9) M(-1) s(-1) for dissolved chlorinated ethylenes and aromatic hydrocarbons, but were 25-60% less for their NAPL forms. The initial dosage of H2O2 and NAPL surface areas (18.4-38.2 mm2) did not significantly affect reaction efficiencies and rate constants of chlorinated NAPLs. Instead, they were related to the octanol-water partition coefficient of compounds. For both dissolved and NAPL forms, aromatic hydrocarbons were more reactive than chlorinated ethylenes in Fenton-like reaction. These results indicated that the decrease in reaction efficiencies and rate constants of NAPL-form contaminants would pose more negative impacts on the less reactive compounds such as benzene and cis 1,2-DCE during goethite-catalyzed Fenton-like reaction.Journal of Hazardous Materials 04/2008; 151(2-3):562-9. · 4.17 Impact Factor -
Article: Emissions of polycyclic aromatic hydrocarbons from thermal pre-treatment of waste hydrodesulfurization catalysts.
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ABSTRACT: Despite increasing environmental concerns and stringent limitations on the sulfur content in fuels, many waste hydrodesulfurization (HDS) catalysts containing Co, Mo, Ni and V are generated in the petroleum refining process. To recover valuable metals in the waste HDS catalysts via hydrometallurgy, thermal treatment is usually performed first to remove contaminants (residual oil, carbon and sulfur) present on the surface of catalysts. In this study, the mass partitions of polycyclic aromatic hydrocarbons (PAHs) in different media (aqueous, particulate and gaseous) were quantified in order to determine the efficiency of three different air pollution control devices, cooling unit, filter and glass cartridge, on PAH removal. An afterburner and two furnace temperatures were used to observe the effect on the PAH contents of the treated residues. Results show that total-PAH content in treated residues decreased with the pyrolysis temperature of the primary furnace, while those generated in flue gases were destroyed by the afterburner at an efficiency of approximately 95%. In addition, the thermal process converts high molecular weight PAHs to low molecular weight PAHs, and the afterburner temperature involved (1200 degrees C) was high enough to prohibit the generation of high molecular weight PAHs (HM-PAHs), leading to the domination of low molecular weight PAHs (LM-PAHs) in flue gases, while treated residues were dominated by HM-PAHs. Finally, information on metal contents and their concentrations in the Toxicity Characteristic Leaching Procedure in waste HDS catalyst and thermal treated residues are examined as an index of the potential for metal recovery.Chemosphere 10/2007; 69(2):200-8. · 3.21 Impact Factor
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Institutions
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2004–2011
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National Pingtung University of Science and Technology
- Department of Environmental Science and Engineering
Pingtung, Taiwan, Taiwan
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2009
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Chung Hwa University of Medical Technology
Tainan, Taiwan, Taiwan
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2003
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Clarkson University
- Department of Civil & Environmental Engineering
Potsdam, NY, USA
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