• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.17-22
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• 2015

International interests in chemical warfare agents (CWAs) have been increased recently because of the use of sarin (GB) in Syrian civil war which caused around 1,300 casualties in 2013. After exposing to natural environments, CWAs undergo hydrolysis or photodegrade to non-toxic degradation byproducts. Generally, CWAs and their degradation byproducts are present at very low concentration (e.g. several ppb), thus pretreatment processes including separation, extraction and concentration are required prior to any analyses. Liquid-liquid extraction and solid-phase extraction (SPE) are common techniques to pretreat environmental samples. Recently, a novel pretreatment method, liquid phase miecoextraction (LPME), has been applied to CWAs analysis, which could reduce amounts of solvent used but promote analytical efficiencies. Fundamental backgrounds of LPME and its application to CWAs analysis were reviewed.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.385-393
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• 2016

Oxidative and thermal degradation of alkanolamines for a promising $CO_2$ capture technology of absorption might cause decrease in $CO_2$ capture efficiency and formation of hazardous byproducts. In this study, characteristics of a representative absorbent of monoehtanolamine (MEA) were examined for a long term operation using a laboratory scale absorption system. An $CO_2$ absorption system with ID 56 mm and absorption zone height 100 cm was developed for the characterization. Absorption solution of 30 wt% MEA was circulated at 100 mL/min to treat air with 15% $CO_2$ and 1 ppm NO at 10 L/min. Temperatures of absorber and stripper were maintained at $40^{\circ}C$ and $120^{\circ}C$, respectively. For the course of 5 weeks continuous operation, MEA concentration was decreased approximately by 70% and $CO_2$ removal efficiency was dropped from 95% to 65%. Ionic byproducts of $NH_4{^+}$, $NO_2{^-}$, and $NO_3{^-}$ were accumulated up to 48 g/mL, 0.2 g/mL, and 1.5 g/mL, respectively, tracking the variation of MEA concentration. Formation of various organic byproducts were also observed.

• Journal of Life Science
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• v.9 no.5
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• pp.581-589
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• 1999

This study was carried out to compare ozonation with photocatalysis degradation for removal Geosmin of algae byproduct. The change of pH was decresed from 7.02 to 2.8 after contact time 480 minute for ozonation. In case of UV-germicidal lamp, pH was very quickly increased from 7.02 to 7.5, but Halogen lamp did very slowly change pH. Geosmin degradation ratio was as following, UV-germicidal lamp/TiO2(100mg/L) O3>UV-germicidal lamp/TiO2(50mg/L)>UV-germicidal lamp(10W)>halogen lamp(50W). Instead of TiO2 suspension solution, Geosmin degradation ratio was very low using hollow bead and pellet as coated TiO2. As a result of identifing byproducts, ozonation generated three species of aldehyde such as 3-Heptanone and three species of alcohol such as Heptanal, but photocatalysis formed 1, 14-Tetradecanediol infinitesimally.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.2
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• pp.128-132
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• 1998

The relative disappearance and rate of degradation of dry matter (DM) and neutral detergent fiber (NDF) of nine different feedstuffs were determined by simultaneously suspending groups of substrates, using the nylon bags, in the rumen of males of Sahiwal cattle and Nili-Ravi buffalo. The digestion kinetics of leguminous forages (Lucerne, berseem and cowpeas) and feed byproducts (cotton seed cake, wheat bran and wheat straw) did not differ between the two species. However, the DM and NDF digestibilities and rates of digestion of grasses and wheat straw were greater in buffalo than in cow bulls, indicating that buffaloes are better converters of poor quality roughages than are Sahiwal. The lag time for DM of grasses did not differ between these two species but the NDF lag time was lower in buffalo than in cows, indicating that both the rate and lag time of digestion may be reliable indicators for assessing the NDF quality.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.10
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• pp.1389-1394
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• 2012

Sheanut cake (SNC), expeller (SNE) and solvent extractions (SNSE) samples were evaluated to determine their suitability in animal feeding. The CP content was highest in SNSE (16.2%) followed by SNE (14.7%) and SNC (11.6%). However, metabolizable energy (ME, MJ/kg) was maximum in SNC (8.2) followed by SNE (7.9) and SNSE (7.0). The tannin phenol content was about 7.0 per cent and mostly in the form of hydrolyzable tannin (HT), whereas condensed tannin (CT) was less than one per cent. The in vitro gas production profiles indicated similar y max (maximum potential of gas production) among the 3 by-products. However, the rate of degradation (k) was maximum in SNC followed by SNE and SNSE. The $t^{1/2}$ (time taken for reaching half asymptote) was lowest in SNC (14.4 h) followed by SNE (18.7 h) and SNSE (21.9 h). The increment in the in vitro gas volume (ml/200 mg DM) with PEG (polyethylene glycol)-6000 (as a tannin binder) addition was 12.0 in SNC, 9.6 in SNE and 11.0 in SNSE, respectively. The highest ratio of $CH_4$ (ml) reduction per ml of the total gas, an indicator of the potential of tannin, was recorded in SNE (0.482) followed by SNC (0.301) and SNSE (0.261). There was significant (p<0.05) reduction in entodinia population and total protozoa population. Differential protozoa counts revealed that Entodinia populations increased to a greater extent than Holotricha when PEG was added. This is the first report on the antimethanogenic property of sheanut byproducts. It could be concluded that all the three forms of SN byproducts are medium source of protein and energy for ruminants. There is a great potential for SN by-products to be incorporated in ruminant feeding not only as a source of energy and protein, but also to protect the protein from rumen degradation and suppress enteric methanogenesis.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.5
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• pp.533-538
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• 1996

The rate and extent of digestion of dietary carbohydrates has a tremendous impact on ruminal fermentation and the productivity of the animals. The objective of the study was to determine the dry matter (DM) and neutral detergent fiber (NDF) degradabilities and rate and extent of feed byproducts (cotton seed cake, wheat bran), legumes [berseem (Egyptian clover), lucern (Medicago sativa), cowpeas (Vigna sinensis)], grasses [maize (Zea mays), millet (Panicum miliaceum), sorghum (Sorghum vulgare)] and wheat straw in ruminally fistulated male buffalo calves. By using nylon bags, 10 grams sample was exposed to the ruminal fermentation for 0, 1, 2, 4, 6, 10, 16, 24, 36, 48 and 96 hours. Dry matter and NDF degradability was measured at 48 hours. Extent of DM and NDF disappearance was determined at each time point. Rates of disappearance of DM and NDF were determined by regressing the natural logarithm of the percentage of original DM and NDF remaining in the bags between 1 and 96 hours. The dry matter digestibility (DMD) of the feed byproducts (FBP) and legume forages when incubated in the rumen of male buffalo calves were greater (p < 0.05) than grasses. Extent of digestion followed similar pattern as DMD. Rate of DMD was higher in FBP than in legumes and was the lowest in the wheat straw. The NDF degradability (NDFD) of FBP, legumes and grasses did not differ, however, wheat straw had the lowest NDFD from all the feeds tested. The lowest NDFD of wheat straw may have been due to the depressing effect of lignin on fiber digestion. The FBP and legumes had higher (p < 0.05) rates and lower extents of NDF digestion than grasses.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.513-520
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• 2006

The effect of chlorination on disinfection byproducts (DBPs) production from bloom-forming freshwater algae including 7 strains of cyanobacteria and 6 strains of diatoms was investigated. The release and degradation of hepatotoxin (microcystins) by the chlorination on Microcystis under differential condition of the chlorination time and dose were also investigated. The disinfection byproducts formation potentials (DBPFP) of cyanobacterial species and diatoms were ranged from 0.017 to $0.070{\mu}mol\;DBPs/mg$ C and from 0.129 to $0.708{\mu}mol\;DBPs/mg$ C respectively. Among three major groups of DBPs, haloacetonitrils (HANs) was major product in most test strains except Aphanizomenon sp. and Oscillatoria sp. Haloacetic acids (HAAs) was less than 5 % of total DBPs. Chloroform and dichloroacetonitril (DCAN) were dominant compounds in trihalomethanes (THMs) and HANs respectively. After 4 hours chlorination of toxic Microcystis aeruginosa under the dose range of 0.5 to $10mg\;Cl_2/L$, the concentration of intracellular microcystins decreased, but dissolved dissolved microcystins concentration increased with the treatment of more than $3mg\;Cl_2/L$. However the total amount of microcystins was almost constant even at $10mg\;Cl_2/L$ of chlorination. To conclude, our results indicate that the chlorination causes algal cell lysis and release of intracellular microcystins in the intact form to surrounding waters.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.E2
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• pp.35-42
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• 2001

Recent development of photocatalytic degradation method that is mediated by TiO$_2$ is of interest in the treatment of volatile organic compounds(VOCs). In this study, trichloroethylene(TCE) and acetone were closely examined in a batch scale of photo-reactor as a function of water vapor, oxygen, and temperature. Water vapor inhibited the photocatalytic degradation of acetone, while there was an optimum concentration in TCE. A lower efficiency was found in nitrogen atmosphere than air, and the effect of oxygen on photocatalytic degradation of acetone was greater than on that of TCE. The optimum reaction temperature on photocatalytic degradation was about 45$^{\circ}C$ for both compounds. NO organic byproducts were detected for both compounds under the present experimental conditions. It was ascertained that the photocatalytic reaction in a batch scale of photo-reactor was very effective in removing VOCs such as TCE and acetone in the gaseous phase.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.149-152
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• 2008

The reaction between iron oxide and ferrous iron is known to be the adsorption of ferrous iron onto the oxide surfaces that produces Fe(II)-Fe(III) (hydr)oxides and ferrous oxide oxidized to ferric ion which is the reducing agent of the target compounds. In our investigations on DS/S using ferrous modified steel slag, the results did not follow the trends. FeO and Fe(II), the major component of steel slag, were used to investigate the degradation of TCE. Degradation did not take place for the first and suddenly degraded after awhile. Degradation of TCE in this system was unexpected because Fe(II)-Fe(III) (hydr)oxides could not be produced in absence of ferric oxide. In this study, the characteristics of FeO/Fe(II) system as a reducing agent were observed through the degradation of TCE, measuring byproducts of TCE and the concentration of Fe(II) and Fe(III). Adsorption of ferrous ion on FeO was observed and the generation of byproducts of TCE showed the degradation of TCE by reduction in the system is obvious. However it did not correspond with the typical reducing mechanisms. Future research on this system needs to be continued to find out whether new species are generated or any unknown mineral oxides are produced in the system that acted in the degradation of TCE.

• Environmental Engineering Research
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• v.25 no.4
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• pp.614-621
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• 2020

Antibiotic pollution is one of the factors contributing to the spread of antibiotic-resistant bacteria in the environment. Advanced oxidation and irradiation processes have been introduced to eliminate antibiotics from water and wastewater. However, few studies have reported the toxic effects of residual antibiotics and their byproducts induced by a treatment system. In this study, we compared the efficacies of chemical (high-performance liquid chromatography (HPLC)) and biological (antimicrobial susceptibility test) assays for measuring the concentrations of residual antibiotics after gamma irradiation for degrading amoxicillin, cephradine, lincomycin, and tetracycline. The concentrations of residual antibiotics estimated using the two assay methods were almost identical, except cephradine. In the case of cephradine, inhibited bacterial growth was observed that was equivalent to twice the concentration measured by HPLC in the samples subjected to gamma irradiation. The observed inhibition of bacterial growth suggested the generation of potentially toxic intermediates following antibiotic degradation. These results indicate that biological and chemical assays should be used in concert for monitoring antibiotic contamination and the toxic derivatives of antibiotic degradation. The results demonstrate that these four antibiotics can be decomposed by 2.0 kGy gamma-irradiation without toxic effects of their byproducts.