• Environmental Analysis Health and Toxicology
• /
• 제18권1호
• /
• pp.63-67
• /
• 2003

Benzoic acid is produced about 700 tons/year in Korea as of 1998 survey. Most is used as a stabilizer in the processes of synthesis of pharmaceuticals and dyes. It is also used for ingradient of paint, disinfections, and antifungals. Due to the antioxidant activity of benzoic acid, the chemical is also used as food preservatives. Although the chemical is widely used in Korea, exposure levels in air, water, soil or sediment have not been monitored or estimated so that risk evaluation of benzoic acid was not possible. In this study, distribution of the chemical among environmental media was estimated using EQC model based on the chemical-physical properties. In Level I and II of which the chemical are hypothesized in equilibrium and no transfer through the media, more than 93％ of benzoic acid are estimated to be distributed in water. However, in Level III of which non-equilibrium and intermedia transfer could be occurred, the chemical is estimated to distributed to soil, 64％ and water,35% as of total amount.

• 한국환경보건학회지
• /
• 제21권4호
• /
• pp.17-23
• /
• 1995

As a basic experiment to develope biological pretreatment proces~ in water treatment, the experiments on biodegradability and isothermal adsorption of activated carbon were performed on refractories such as humic acid, $NH_3-N$, phenol and ABS which caused the problems in drinking water treatment. Also, the treatabilities on humic acid were examined in the continuous flow type reactors. The removal efficiencies of humic acid, $NH_3-N$, phenol and ABS in the biodegradable experiments for 5 days were 20.1%, 73.4%, 91.7% and 97.5%, respectively. In the isothermal adsorption test of refractories on activated carbon to be used as a media in the continuous flow type reactors, ABS and phenol are adsorbed easily, but humic acid and $NH_3-N$ are difficult to be done. The removal efficiencies of humic acid in granular activated carbon(GAC) reactor were about 7-8% higher than in biological activated carbon(BAC) reactor. The removal efficiencies of humic acid in biological fluidized bed(BFB) reactor were about 30% in GAC media, but were almost zero in sea sand media.

• 한국자동차공학회논문집
• /
• 제8권5호
• /
• pp.181-187
• /
• 2000

Fatigue tests under acid fog environment were carried out to investigate the effect of acid fog on the corrosion fatigue strength of SM55C in comparison with distilled water. Main results obtained are as follows. The fatigue strength of SM55C under acid fog environment are remarkably decreased as compared with that of distilled water specimen. The corrosive effect of acid fog on fatigue strength are more serious under low stress amplitude level than under high stress amplitude level, and this leads to continuous reduction of fatigue strength. Under acid fog environment in early stage of crack growth. because the corrosive components dissolve the crack face offensively. the unstable fracture surface appears. But, the stable corrosion precipitation and products layer are formed on the fracture surface in accordance with the time pass.

• 한국응용과학기술학회지
• /
• 제33권3호
• /
• pp.411-420
• /
• 2016

The objective of this study was to determine the effect of drinking water containing trimethyl glycine or ascorbic acid on growth performance and blood parameter profiles of duck exposed to scorching heat stress. A total of 480 ducks were randomly assigned to the following eight experiment groups for 42 days : control group C with general water, treatment group 1 (T1) with drinking water containing 100 ppm ascorbic acid, treatment group 2 (T2) with drinking water containing 200 ppm ascorbic acid, treatment group 3 (T3) with drinking water containing 300 ppm ascorbic acid, treatment group 4 (T4) with drinking water containing 400 ppm trimethyl glycine, treatment group 5 (T5) with drinking water containing 800 ppm trimethyl glycine, treatment group 6 (T6) with drinking water containing 1,200 ppm trimethyl glycine, treatment group 7 (T7) with electrolytes of KCl (0.5%) + $NaHCO_3$ (1.0%)+NaCl (0.5%). Our results revealed that the body weights and feed intakes of treatment groups, especially T3 and T6, were increased compared to the control group, where as the feed conversion ratios of treatment groups were decreased (p<0.05). Blood levels of total cholesterol, triglyceride, LDL-C, glucose, AST, ALT and pH in treatment groups were lower compared to those in the control group (p<0.05). Blood levels of red blood cell, platelets profiles, electrolyte and gas in treatment groups were higher compared to those of the control group (p<0.05).

• 한국응용과학기술학회지
• /
• 제20권4호
• /
• pp.372-376
• /
• 2003

Water-soluble cutting fluids are used for processing of aluminium materials. This short article describes properties of new additives of water-soluble cutting fluids for aluminium materials. Various Diels-Alder adducts of unsaturated fatty acids with acrylic acid of maleic anhydride were prepared by thermal reactions. Triethanolamine salts of Diels-Alder adducts of dehydrated castor oil fatty acids with acrylic acid or maleic anhydride showed excellent anti-corrosion property of aluminium materals. These thermal adducts showed anti-rust property for cast-iron chips, too.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.316-325
• /
• 2018

Aluminum based metal-organic framework using a di-carboxylate linker succinic acid (Al-SA MOF), are synthesized in water with minimal generation of secondary pollutants. The physicochemical properties of Al-SA MOF were examined, followed by its utility for the adsorption of Acid Black 1 (AB1) in aqueous media. Influences of key parameters such as pH, contact time, initial AB1 concentration,temperature, and selectivity on the adsorption process were assessed. A series of adsorption mechanisms are proposed, which involve electrostatic, hydrogen bonding, and hydrophobic interactions. These findings suggest that Al-SA MOF is a potent candidate in removing complex azo dyes molecules from aqueous media.

• 한국환경과학회지
• /
• 제7권2호
• /
• pp.149-156
• /
• 1998

Enoronmental problems caused by certain geologic conditions Include pollution of soil by heavy metal, acidization of souls , acid mine drainage, Pound-water pollution, and natural radioactivity, as well as zoo-logical hazards such as landslide and subsidence. The acrid mine drainage contains large amount of heavy metals nO, therefore. cause serious pollution onto the nearby drainage systems and soils. In spite of this prospective environmental danger, few studies have been done on the acid mine drainage derived from non-metallic ore deposits such as pyrophyllitefNapseok) deposits. The sudo-bearing pyrophyllite ores, alteration zones, and mine talllngs of pyrophylllte deposits produce acrid mine drainage by the okidation of weathering. Compared to the fresh host rocks, the ores and altered rocks of pyrophyllite deposits produce acidic solution which contain higher amount of heavy metals because of OeP lower buffering capacity to acrid solution. The pus of urine water and nearby stream water of pyrophyllite deposits are 2.1~3.7, which are strong- ly acidic and much lower than that (6.2~7.2) of upstream water and than that (6.8~7.6) of the stream water derived from the non-mineralized area. This study reveals that this acrid mine drainage can affect the downstream area which is 8km far from the pyrophyllite deposits, even though the drain Is diluted with abundant non-contaminated river water This suggmists that not only acid mine drainage but also the sulfide-bearing sediments originated from the pyrophyllite deposits move downstream and form acidic water through continuous oxidation reaction. The heavy metals such as Pb, Zn, Cu, Cd, Nl, Mn and Fe are enriched In the mine water of low pH, and their contents decrease as the pH of mine water Increases because of the Influx of fresh stream wainer. SoUs of the Pyrophyulte deposits are characterized by high contents of heavy metals. The stream sediments containing the yellowish brown precipitates formed by neutralization of acid mine drainage occur in all parts of the stream derived from the pyrophyllite deposits, and the sediments also contain high amounts of heavy metals. In summary, the acid mine drainage of the pyrophyllite deposits is located in the upstream part of Hoidong water reservoir in Pusan contains large amounts of heavy metals and flows into the Holdong water reservoir without any purification process. To protect the water of Holdong reservoir, the acid mine drainage should be treated with a proper purification process.

• 한국자원식물학회지
• /
• 제19권2호
• /
• pp.204-208
• /
• 2006

콩나물의 생산과정에서 야기되고 있는 부패를 방지하기 위한 다양한 방법이 제시되고 있다. 본 연구는 물에 침종하는 수침(水浸)을 이용한 종자정선과 0.1% acetic acid에 2분간 실시한 종자소독이 콩나물의 발아와 생장, 형태 및 생산수율에 미치는 영향을 조사하고자 실시하였던 바 그 결과를 요약하면 다음과 같다. 1. 물에 뜨는 부유 종자의 비율은 5분간 물에 침종시킨 종자를 건져 40분간 aeration 시켜 다시 물에 침종시킬 경우 가장 높았다. 2. 상품으로 판매가 가능한 하배축 길이가 4cm이상의 비율은 은하콩에서는 水浸(水浸)과 acetic acid 처리간 차이가 없었던 반면, 풍산 나물콩과 준저리에서는 acetic acid 처리에 비하여 가결 수침 처리(水浸 處理)에서 높았다. 3. 세근형성 비율과 개체당 세근수는 은하콩과 준저리에서는 수침 처리(水浸 處理)에서, 풍산나물콩은 acetic acid 처리에서 상대적으로 높고 많았다. 4. 개체당 전체생계중은 은하콩과 풍산나물콩에서는 수침 처리(水浸 處理) 보다는 acetic acid 처리에서 많았던 반면. 준저리는 이와 반대의 결과를 보였다. 그러나 준저리를 이용한 대량생산 체계에서의 생산 수율은 수침(水浸)을 이용한 종자정선과 acetic acid를 이용한 종자소독간에 차이가 없었다.

• Composite Materials and Engineering
• /
• 제3권3호
• /
• pp.167-178
• /
• 2021

In the present paper, the destructive behavior of distilled water, salty water, sulfuric acid, and heat on glass/vinyl ester composites was investigated by experimental methods. Hetron 922 vinyl ester resin and two types of mat and woven glass fibers as the reinforcements were used to fabricate composite test samples. All samples were immersed in distilled water, salty water, and sulfuric acid with three different concentrations. The tests were performed at 20℃ and 70℃ for the exposure duration of 1, 2, 4, and 8 weeks. Bending tests were performed after aging for all composite samples to check the degradation of the bending modulus and strength. The results show that the effect of distilled water, in comparison with salty water, on the degradation of composite samples was significant. On the other hand, almost non-sensitivity of concentrations of salty water on the weight gain of specimens has been observed. In addition, it was also observed that the degradation of samples at 70℃ temperature is much more than that of at 20℃. Also, it was observed that the flexural modulus of virgin specimens exposed to salty water (2% concentration) has been recovered just after two weeks of immersion. Furthermore, in some cases, composite samples under the sulfuric acid solution have lost almost 80% of their mechanical properties.

• Journal of Microbiology and Biotechnology
• /
• 제23권2호
• /
• pp.260-266
• /
• 2013

Rhodococcus sp. strain p52, a previously isolated dibenzofuran degrader, could effectively inhibit the growth of cyanobacteria, including species of Microcystis, Anabaena, and Nodularia. When strain p52 was inoculated at the concentration of $7.7{\times}10^7$ CFU/ml, 93.5% of exponentially growing Microcystis aeruginosa ($7.3{\times}10^6$ cells/ml initially) was inhibited after 4 day. The threshold concentration for its algicidal activity against M. aeruginosa was $7.7{\times}10^6$ CFU/ml. Strain p52 exerted algicidal effect by synthesizing extracellular substances, which were identified as trans-3-indoleacrylic acid, DL-pipecolic acid, and L-pyroglutamic acid. The effective concentrations of trans-3-indoleacrylic acid and DL-pipecolic acid against M. aeruginosa were tested to be 0.5 mg/l and 5 mg/l, respectively.