• Journal of Environmental Science International
• /
• v.4 no.1
• /
• pp.91-103
• /
• 1995

The reaction rate, equilibrium, and flow injection analysis methods were fundamentally evaluated for the determination of aqueous ammonia. The selected indophenol blue method was based on the formation of indophenol blue in which ammonium ion reacted with hypochlorite and phenol in alkaline solution. In the optimized reaction condition, the reaction followed 1st order reaction kinetics and the final product was stable. The absorbance measurements before and after the equilibrium were utilized for the reaction rate and equilibrium methods. The reaction rate methods, based on the relative analytical signals for the possibility of eliminating interferents, were shown to have good linear calibration curves but the detection limit and the calibration sensitivity were poorer than those in the equilibrium method. The detection limits were 32-49 pub and 24 pub for the reaction rate and equilibrium methods, respectively In the flow injection analysis, the absorbance was measured before the equilibrium reached and thus resulted in 30% reduction of calibration sensitivity. However, the detection limit was 11 ppb, indicating that the peak-to-peak noise for the blank was remarkably improved. Compared to the manual methods, the optimized experimental condition in a closed reaction system reduced the blank absorbance and the inclusion of ammonia from the atmosphere was prevented. In addition, highly reproducible mixing of sample and reagents and analytical data extracted from continuous recording showed excellent reproducibility.

• Journal of Korean Society on Water Environment
• /
• v.27 no.4
• /
• pp.516-522
• /
• 2011

This study was performed to investigate the removal characteristics of phosphate by adsorption on olivine, which is generated as industrial by-products from quarry. The adsorption of phosphate on olivine was significantly achieved within 1 hour and equilibrated after 3 hours. The adsorption capacity of phosphate was enhanced with decreasing pH. The maximum adsorption capacity was observed to be 0.463 mg/g in the condition of pH 3. The $Ca^{2+}$ and $Mg^{2+}$ ion amount per adsorbent eluted from olivine was increased with decreasing pH. The precipitation test showed that phosphate in aqueous phase under the condition of pH 3 ~ 9 could be eliminated largely by adsorption on olivine, not precipitation. Freundlich adsorption model were successfully applied to describe the adsorption behavior of phosphate on olivine. The $q_m$ of Langmuir adsorption model were 1.3369 mg/g, 1.0544 mg/g, 1.0288 mg/g at pH 3, 6 and 9, respectively. The $K_F$ of Freundlich adsorption model were 0.4247 mg/g, 0.3399 mg/g, 0.2942 mg/g at pH 3, 6 and 9, respectively. The olivine showed high feasibility as a adsorbent for the removal of $PO_4$-P.

• Journal of Environmental Health Sciences
• /
• v.12 no.1
• /
• pp.1-14
• /
• 1986

This investigation was carried out on the study of Ferrite formation by aerial oxidation of Fe $(OH)_2$ suspension of aqueous solution containing heavy metal ions. In this study the optimum reactionary condition of the Ferrite formation in Batch reactor wa studied by aerial oxidation which are subjected to various reaction time and temperature, under the different kinds of R(2NaOH/$FeSO_4$) Values, pH, Air flow rate, and $Fe^2+/M^2+$ mole ratio. The optimum condition for the Ferrite formation in Batch reactor was such that residence Time was 90 min., Temperature $65{\circ}$C, pH 11.0, Air flow rate 2.0l/min and $Fe^{2+}/M^{2+}$ mole ratio 4.0, which was observed by X-Ray diffraction analysis. The relation R-value, pH and ORP affecting the formation of Ferrite is that the jump step in pH 11.0, when a amount of NaOH is added, is steady state to the formation of Ferrite. Effect of R-value of $FeSO_4$ and $FeCl_2$ on the formation of Ferrite in different from each other the optimum condition of the in different from each other the optimum condition of the $FeCl_2$ is R-value 0.7, pH 11.0 and the $FeSO_4$ R-value 1.2, pH 11.0.

• Journal of Animal Science and Technology
• /
• v.47 no.5
• /
• pp.789-804
• /
• 2005

This study was conducted to determine effects of supplementation levels of aqueous direct-fed microbials (DFM; Bacillus spp.) to TMR(exp. 1.) and aqueous DFM addition under the various ratios of starch and cellulose(exp. 2.) on ruminal fermentation and fibrolytic enzyme activity. In experiment 1, ruminal fluids taken from rumen-cannulated Holstein cows were incubated during 24 hr by using TMR as substrates. Aqueous DFM was applied at a rate of 0, 0.025 and 0.05%, respectively. The pH of 0.025% treatment was not significantly different from that of control at 6 and 9 hr, but it was significantly lower (P<0.05) than 0.05% treatment. Concentrations of ammonia-N and VFAs were not affected by supplementing aqueous DFM. The A:P ratio of 0.05% treatment was significantly increased(P<0.05) by supplementation of aqueous DFM as compared with that of control at 24 hr. Although overall fibrolytic enzyme activities were not significantly affected by supplementing aqueous DFM, CMCase(carboxymethylcellulase) activity showed significant increase(P<0.05) compared to control at 6hr. However, the xylanase activity of 0.05% treatment significantly decreased(P<0.05) at 12 hr due to the application of aqueous DFM. There was no significant difference for in vitro dry matter disappearance among treatments. In experiment 2, ruminal fluids were incubated under the condition of various ratios of starch to cellulose(90:10, 70:30, 50:50, 30:70 and 10:90) with or without aqueous DFM(0.025%). Ruminal pH was unaffected by the addition of aqueous DFM, however, as increased level of starch, ruminal pH partially showed significant decrease(P<0.05). Ammonia-N concentration was not affected by aqueous DFM and ratio of starch and cellulose. On 9 hr incubation, DFM addition at a ratio of 70:30 showed significantly (P<0.05) lower value of ammonia-N(35.65 mg/dL) than that(65.05 mg/dL) of control. Concentrations of VFAs were significantly increased(P<0.05) by aqueous DFM addition compared with control at the same ratio on 6 hr incubation. The overall CMCase activity was not affected by aqueous DFM addition. However, the xylanase activity by aqueous DFM partially showed significant differences at the ratios of 90:10, 30:70 and 10:90. Our results indicated that supplementation of aqueous DFM did not significantly improve in vitro fermentation and fibrolytic enzyme activity. In addition, the DFM utilized in this study did not show consistent results by having various effects on ruminal fermentation under different feeding regimens.

• Journal of Industrial Technology
• /
• v.21 no.B
• /
• pp.141-147
• /
• 2001

For the preparation of calcium carbonate particles from aqueous $Ca(OH)_2$ slurry, carbonation reaction of aqueous $Ca(OH)_2$ slurry was carried out by batch method the $CO_2$ into reactor filled with aqueous slurry of $Ca(OH)_2$. The concentration of $Ca(OH)_2$ varies from 1.00 to 7.00wt%, reactor temperature at 20 and $40^{\circ}C$, and reactor pressure from atmospheric pressure to $6.0kg_f/cm^2$. Crystal structure of calcium carbonate was of calcite, the particle size were about $0.05{\sim}2.0{\mu}m$, and the particle shape was cubic and spindle. When reactor temperature was higher, particle size of calcium carbonate was bigger and particle shape was varied, but reaction rate was increased. When reactor pressure was higher, particle size of calcium carbonate was smaller, particle shape was cubic, and reaction rate was increased.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.10
• /
• pp.3293-3303
• /
• 1996

Numerical analyses have been performed to estimate the absorption heat and mass transfer coefficients in absorption process of the LiBr aqueous solution and the total heat and mass transfer rates in a vertical tube absorber which is coolING ed by air. Axisymmetric cylindrical coordinate system was adopted to model the circular tube and the transport equations were solved by the finite volume method. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by water vapor in tube. Effects of film Reynolds number on heat and mass transfer coefficients have been also investigated. Especially, effects of tube diameter have been considered to observe the total heat and mass transfer rates through falling film along the tube. Based on the analysis it has been found that the total mass transfer rate increases rapidly in a region with low film Reynolds number(10 ~ 40) as the film Reynolds number increases, while decreases beyond that region. The total heat and mass transfer rates increase with increasing the tube diameter.

• Preventive Nutrition and Food Science
• /
• v.21 no.4
• /
• pp.355-360
• /
• 2016

The influence of extraction temperature, powder concentration, and extraction time on the antioxidant properties of aqueous ginger extract was investigated. The possibility of estimating the antioxidant properties of the extract from its absorbance and colour properties was also investigated. Results indicated that powder concentration was the most significant factor to consider in optimizing antioxidant extraction. However, temperature and time still influenced the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity while extraction temperature influenced the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the extract. Using the total phenol content, total flavonoid content, ABTS radical scavenging activity, and DPPH radical scavenging activity of the extract, the multiresponse optimization condition for extraction of antioxidant based on the experimental range studied is $96^{\circ}C$, 2.10 g/100 mL, and 90 min. The absorbance of the ginger extract at 610 nm could be exploited for rapid estimation of its total flavonoid and polyphenol with a $R^2$ of 0.713 and 0.753, respectively.

• Journal of Korean Society on Water Environment
• /
• v.20 no.5
• /
• pp.466-472
• /
• 2004

Red mud is formed as a waste during bauxite refining known as Bayer's process. Its main constituents are iron, aluminium, sodium and silica. The disposal of large quantities of wasted red mud causes a serious ecological problem. In this study, the red mud wasted from the bauxite refinery was studied for phosphate removal from aqueous solution according to activation methods. The influence of heat treatment, and neutralization with sea water and acid treatment level for the optimum conditions for phosphate removal have been determined. Heat treatment combined with acid treatment is most suitable for the removal of phosphate from aqueous solution. The optimal condition was activated with 1 N HCl solution after heating in $600^{\circ}C$ during 4 hours. Acid and heat treatment causes sodalite compounds which hinder the phosphate adsorption to leach out. The adsorption data obtained followed a first-order rate expression and fitted well with the Freundlich Isotherm well.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.10
• /
• pp.2978-2982
• /
• 2013

A doubly tethered $N-CH_3$ amide chiral stationary phase (CSP 4) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of an antiarrythmic agent, tocainide, and its analogues and the chromatographic resolution results were compared with those on a singly tethered N-H amide CSP (CSP 1), a singly tethered $N-CH_3$ amide CSP (CSP 2) and a doubly tethered N-H amide CSP (CSP 3) under an identical aqueous mobile phase condition. CSP 4 was found to be generally better than other CSPs in terms of the separation factors (${\alpha}$) and resolutions (RS). The retention times of analytes denoted by the retention factors ($k_1$) on CSP 4 were quite long compared to those on other CSPs because of the improved lipophilicity of CSP 4. The long retention times of analytes on CSP 4 were successfully controlled by the addition of a small amount of ammonium acetate to aqueous mobile phase without hurting the chiral recognition efficiency. The variation of the content and type of organic and acidic modifier in aqueous mobile phase was found not to change the chiral recognition efficiency significantly.

• The Korea Journal of Herbology
• /
• v.25 no.2
• /
• pp.65-70
• /
• 2010

Objectives : Biological activities of marine resources have been rarely evaluated compared with other herbal medicines. In the present study, we aimed to evaluate antimicrobial activities of aqueous and ethanolic extracts of five marine resources(Porphyra tenera, Laminariae Thallus, Sargassum, Ostreae Concha, Maliotidis Concha) against Propionibacterium acnes. Methods : Aqueous axtracts of five marine resources were prepared by decocting in tenfold tap water for 3 h. Etanolic extracts were obtained by extracting five marine resources with tenfold ethanol for 72 h at room temperature. The zone of growth inhibition and minimum inhibitory concentration (MIC) were determined against P. acnes after incubation for 48 h under anaerobic condition. Results : Ethanolic extracts of Porphyra tenera exhibited potent antimicrobial effects(MIC $62.5\;{\mu}g/m{\ell}$ against KCTC3320, MIC $31.25\;{\mu}g/m{\ell}$ against KCTC5527). However, all aqueous extracts tested had no effects on the growth inhibition of P. acnes. In addition, four ethanolic extracts except Porphyra tenera showed little inhibitory effect. Conclusions : These results indicate that ethanolic extracts of Porphyra tenera has antimicrobial activities against P. acnes and also warrant further development of Porphyra tenera extracts as a natural anti-acne agent.