Jong-Kwon Im

Ultrasonic degradation of acetaminophen and naproxen in the presence of single-walled carbon nanotubes

Ultrasonic (US) and single-walled carbon nanotube (SWNT)-catalyzed ultrasonic (US/SWNT) degradation of a pharmaceutical (PhAC) mixture of acetaminophen (AAP) and naproxen (NPX) used as analgesics was carried out in water. In the absence of SWNTs, maximum degradations of AAP and NPX occurred at a high frequency (1000 kHz) and under acidic conditions (pH 3) and different solution temperatures (25 °C at 28 kHz and 35 °C at 1000 kHz) during US reactions. Rapid degradation of PhACs occurred within 10 min at 28 kHz (44.5% for AAP; 90.3% for NPX) and 1000 kHz (39.2% for AAP; 74.8% for NPX) at a SWNT concentration of 45 mgL(-1) under US/SWNT process, compared with 28 kHz (5.2% for AAP; 10.6% for NPX) and 1000 kHz (29.1% for AAP; 46.2% for NPX) under US process. Degradation was associated with the dispersion of SWNTs; small particles acted as nuclei during US reactions, enhancing the H2O2 production yield. NPX removal was greater than AAP removal under all US-induced reaction and SWNT adsorption conditions, which is governed by the chemical properties of PhACs. Based on the results, the optimal treatment performance was observed at 28 kHz with 45 mgL(-1) SWNTs (US/SWNT) within 10 min.

Kinetics and degradation mechanism of clofibric acid and diclofenac in UV photolysis and UV/H2O2 reaction

AbstractIn this study, we investigated the removal of the selected pharmaceuticals, clofibric acid and diclofenac, using UV photolysis and UV/H2O2 reactions. The degradation of diclofenac during UV photolysis reaction was faster than that of clofibric acid. Diclofenac was mainly removed by photolysis reaction; clofibric acid was more sensitive to OH radical. More effective removals of clofibric acid and diclofenac were observed when H2O2 was added in the UV photolysis reaction. The competition kinetics showed that the second-order rate constant between the OH radical and the pharmaceuticals was 5.57 × 109 M−1 s−1 for clofibric acid and 2.45 × 109 M−1 s−1 for diclofenac, respectively. The major reaction intermediates during the UV photolysis and UV/H2O2 reactions of clofibric acid were 4-chlorophenol and hydroquinone, and these intermediates were degraded as phenol with further reaction.

The Estimation of Emission Factor of N₂O and CH₄ by Measurement from Stacks in the Waste Incinerators and Cement Production Plants

The purpose of this study is to estimate the emission factor of non-CO₂ global warming gases such as N₂O and CH₄ by measuring concentrations from stacks of waste incinerators and cement production plants. Based on the established monitoring methods, N₂O concentration measured from stacks in incinerator were between 0.62 and 40.60 ppm v (ave. 11.50 ppm v ). The concentration of N₂O was dependent on the incinerator types. However, the concentrations of CH4 gas were between 2.65 and 5.68 ppm v (ave. 4.22 ppm v ), and did not show the dependency on the incinerator types. In the cement production plant, the concentration ranges of N₂O from the stack were from 6.90 to 10.80 ppmv (ave. 8.60 ppm v ), and CH4 were between 1.80 and 2.20 ppm v (ave. 2.60 ppm v ). Using measured concentrations, the emission amounts of N2O and CH4 from stacks per year were calculated. The results were is 4.2 ton N₂O/yr in the incinerators, and 53.7 ton N₂O/yr in the cement facilities. The big difference is from the flow rate of flue gas in the cement facilities compared to the incinerators. By the same reason, the CH₄ emission amounts in cement plant and incinerator was found to be 339 ton CO₂/yr and 34.1 ton CO₂/yr, respectively. Finally, the emission factor of N2O in the incinerators were calculated using the measured concentration and the amount of incinerated wastes, and was 42.5~799.1 g/ton in kiln and stoker type, 11.9~79.9 g/ton in stoker type, 90.1 ton/g in rotary kiln type, 174.9 g/ton in fluidized bed type, and 63.8 g/ton in grate type, respectively. Also, the emission factors of CH₄ were found to 65.2-91.3 g/ton in kiln/stoker type, 73.9-122 g/ton in stoker type, 109.5 g/ton rotary kiln, and 26.1 g/ton in fluidized bed type. This result indicates that the emission factor in incinerators is strongly dependent on the incinerator types, and matched with result of IPCC (International Panel on Climate Change) guideline.

Quantitative Determination of PFOA and PFOS in the Effluent of Sewage Treatment Plants and in Han River

Perfluorinated compounds (PFCs) have a wide range of domestic and industrial applications, but they are persistent in the environment. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are among the metabolites of PFCs and occur at high concentration in the environment. Korea is the largest importer of PFC compounds in the world, therefore, the accumulation of these compounds is possible. In this study, the concentrations of PFOS and PFOA were determined in water samples taken from sewage treatment plants (STPs) and the Han River in Seoul, Korea. After extraction with a HLB cartridge, PFCs in the samples were analyzed by HPLC with an ion trap mass spectrometry in electrospray negative mode. Limits of detection was between 1 and 1.6 ng/l. The result showed that the concentrations of PFOS and PFOA in effluent and influent of the four STPs in Seoul were 60 ~ 570 ng/l, and not detected (nd) ~ 254 ng/l, respectively. The levels of PFOS and PFOA were higher in the effluents which passed through the treatment process than in influent water samples which was against expectation. The concentration of PFOA and PFOS in the Han River was 60 ~ 570 ng/l and nd ~ 254 ng/l, respectively. PFOA was detected in every sample, but PFOS was only detected in the downstreams of the Han River. This result indicates that there is comprehensive contamination of PFCs in the aquatic environment in Korea.Perfluorinated compounds (PFCs) have a wide range of domestic and industrial applications, but they are persistent in the environment. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are among the metabolites of PFCs and occur at high concentration in the environment. Korea is the largest importer of PFC compounds in the world, therefore, the accumulation of these compounds is possible. In this study, the concentrations of PFOS and PFOA were determined in water samples taken from sewage treatment plants (STPs) and the Han River in Seoul, Korea. After extraction with a HLB cartridge, PFCs in the samples were analyzed by HPLC with an ion trap mass spectrometry in electrospray negative mode. Limits of detection was between 1 and 1.6 ng/l. The result showed that the concentrations of PFOS and PFOA in effluent and influent of the four STPs in Seoul were 60~570 ng/l, and not detected (nd)~254 ng/l, respectively. The levels of PFOS and PFOA were higher in the effluents which passed through the treatment process than in influent water samples which was against expectation. The concentration of PFOA and PFOS in the Han River was 60~570 ng/l and nd~254 ng/l, respectively. PFOA was detected in every sample, but PFOS was only detected in the downstreams of the Han River. This result indicates that there is comprehensive contamination of PFCs in the aquatic environment in Korea.

Optimization of naproxen and ibuprofen removal in photolysis using a Box–Behnken design: Effect of Fe(III), NO3 −, and humic acid

This study investigated the roles and optimum conditions of four independent variables [ultraviolet (UV) intensity, Fe(III), NO3 −, and humic acid (HA) concentration] in the photolytic removal of naproxen (NPX) and ibuprofen (IBP) in water using a response surface method based on the Box–Behnken design. Lab-scale experiments used analysis of variance and t-test statistics to test the significance of independent variables and their interactions. Predicted levels of NPX and IBP removals were found to be in good agreement with experimental levels (R2 = 0.9891 for NPX and 0.9936 for IBP). UV intensity and HA were the most positively and negatively significant variables (P < 0.001), respectively. However, Fe(III) and NO3 − ions had a less significant impact (P > 0.05). This result implies that NPX was removed by both direct photolysis (photons) and indirect reaction (OH radical), while IBP was removed mainly by the OH radical. NPX was more susceptible to the OH radical than IBP (kOH/NPX = 8.24 × 109 M−1s−1 and kOH/IBP = 7.51 × 109 M−1s−1). According to a quadratic regression model, the predicted maximum removal efficiencies for NPX and IBP were 71.66% and 63.58% when the predicted optimum ratio of UV (mW cm−2):Fe(III) (mg/L):NO3 − (mg/L):HA (mg/L) was 6.3:0.94:0:0 and 6.3:0.94:20:0, respectively, which was similar to the respective experimental NPX and IBP removal values of 70.21% and 62.16%. Supplemental materials are available for this article. Go to the publishers online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

PM 10 and CO 2 Concentrations in the Seoul Subway Carriage

【The subway is the major public transportation system in Seoul with 2.2 million people using it everyday. Indoor air pollution in the subway can be a significant part of population exposure because of the number of people using the subway, time spent in transit and potentially high exposure for certain pollutants. The Korea Ministry of Environment has established the level 2 of recommended standards of

Sonocatalytic-TiO2 nanotube, Fenton, and CCl4 reactions for enhanced oxidation, and their applications to acetaminophen and naproxen degradation

PM_{10}

Enhanced ultrasonic degradation of acetaminophen and naproxen in the presence of powdered activated carbon and biochar adsorbents

and

Organic fouling and reverse solute selectivity in forward osmosis: Role of working temperature and inorganic draw solutions

CO_2

Sonocatalytic degradation coupled with single-walled carbon nanotubes for removal of ibuprofen and sulfamethoxazole

in subway trains. The aims of this study were to determine the airborne levels of