• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2269-2273
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• 2012

Pseudo-first-order rate constants $k_{amine}$ have been measured spectrophotometrically for the reactions of benzyl 4-pyridyl carbonate 6 with a series of alicyclic secondary amines in $H_2O$ at $25.0^{\circ}C$. The plots of $k_{amine}$ vs. [amine] curve upward, indicating that the reactions proceed through a stepwise mechanism with two intermediates, a zwitterionic tetrahedral intermediate $T^{\pm}$ and its deprotonated form $T^-$. This contrasts to the report that the corresponding reactions of benzyl 2-pyridyl carbonate 5 proceed through a forced concerted pathway. The $k_{amine}$ values for the reactions of 6 have been dissected into the second-order rate constant $Kk_2$ and the thirdorder rate constant $Kk_3$. The Br${\o}$nsted-type plots are linear with ${\beta}_{nuc}=0.94$ and 1.18 for $Kk_2$ and $Kk_3$, respectively. The $Kk_2$ for the reaction of 6 is smaller than the second-order rate constant $k_N$ for the corresponding reaction of 5, although 4-pyridyloxide in 6 is less basic and a better nucleofuge than 2-pyridyloxide in 5.

• Journal of Korean Medical classics
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• v.36 no.4
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• pp.93-108
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• 2023

Objectives : This paper aims to study the characteristics of zhongfeng treatment by examining the eight principles of zhongfeng treatment in the Zhongfeng Jiaoquan of Zhang Shanlei along with Zhang Bolong's treatment of 'Yangxu Leizhongfeng[Yang deficiency pseudo Wind damage]' which is missing from the eight principles. Methods : The treatment methods in the Zhongfeng Jiaoquan was organized in the order of cause, characteristic, symptom, treatment, and precautions, in order to analyze features that were emphasized by Zhang in zhongfeng treatment. Results : First, treatment for bizheng is to 'open and close', then apply methods of 'qianyang jiangqi(潛陽降氣)' and 'zhenni huatan(鎭逆化痰)' while that for tuozheng is to 'lianyin yiye(戀陰益液)' accompanied by medicinals that 'qianzhen xutang(潛鎭虛陽)'. Second, treatment for ganyang shangnizheng is to 'qianzhen rougan', while for tanzian yongsezheng, one must 'dangdi(蕩滌)' for those who are strong in qi, 'xiehua(泄化)' for those who are weak in qi, while for those who have qinizheng[qi reverse syndrome] to 'shunqi(順氣).' Third, for deficiency in xinye and ganyin, one must 'yuyin yangxue[育陰養血]', while for deficiency in shenyin, one must first 'qianjiang shena[潛降攝納]' then slowly apply the method of 'ziyang shenyin[滋養腎陰]' if there is no phlegm turbidity. Fourth, in order to communicate the meridians and unfold collaterals, if the pathogen is external, apply the method of 'yangxue tongluo[養血通絡]', while if the pathogen is internal, calm by doing 'qianyang zhenni[潛陽鎭逆].' Fifth, in order to treat pseudo zhongfeng caused by yang deficiency, one must 'lianyin gutuo[戀陰固脫]' while using medicinals that 'jiangxiang[潛降]'. Conclusions : Treatment of zhongfeng in the Zhongfeng Jiaoquan diverged from 'wenjing sanhan', the usual approach to zhongfeng which sees it as external, and established the 'qianjiang zhenshe [潛降鎭攝]' treatment method based on the internal wind theory. It suggests a new Korean Medical pathology based on theories of Western medicine, and introduces eight principles in treating zhongfeng, which would influence the treatment of zhongfeng in the future.

• Journal of Korean Society for Atmospheric Environment
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• v.6 no.1
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• pp.1-10
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• 1990

The purpose of the study was to analyze air quality in underground shopping centers using pattern recognition methods. In order to perform this, the concentraion of air pollutants such as $CO, NO_2, NO_x, SO_2$, and particulate matters was measured at the 11 different shopping centers in Seoul metropolitan area and the total of 47 samples were obtained at random based on the size of shopping centers. To introduce a new concept of the "average concentration" for the indoor air quality analyses, the various multivariate statistical analyses have been studied. Thus, a cluster analysis was applied to separate the samples into pseudo-patterns and a disjoint principal component analysis was used to generate homogeneous patterns after removing outliers from the pseudo-patterns. The 6 homogeneous patterns were then obtained as follows:the first pattern was a group of clean sites;the second a group of sites having high dust concentration;the third a group of sites having high dust and $NO_x$ concentration;the fourth a group of sites having low dust and $SO_2$ concentraion and high CO concentration;the fifth a group of sites having high $NO_2 and SO_2$ concentration;and the final a group of miscellaneous sites. Thus, the average concentration could be estimated for each pattern.h pattern.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.269-273
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• 2001

Biosorption of Pb was evaluated for plants, Persicaria chinensis, Oenanthe javanica and Salvinia natnas. The adsorption equilibrium was reached in about 1hr for Pb and the highest adsorption capacity was 150mg Pb/g biomass at S.natans. Pb adsorption process showed a pseudo second order irreversible reaction. The highest initial adsorption rate was 2000mg pb/g biomass/hr at O.javanica. In spite of pH variation, Pb adsorption capacity by was selection, Pb was selectively adsorved. The selectivity of mixture solution showed the adsorption order of Pb>Cu>Cr>Cd. The Pb adsorption capacity of P. chinensis pretreated with NaOH was increased by 30% in comparison with that of no treatment.

• Environmental Engineering Research
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• v.13 no.2
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• pp.79-84
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• 2008

Adsorption of heavy metals by sawdust was investigated to evaluate the effectiveness of using sawdust to remove heavy metals from aqueous solutions. Kinetic and isotherm studies were carried out by considering the effects of initial concentration and pH. The adsorption isotherms of heavy metals fitted the Langmuir or Freundlich model reasonably well. The adsorption capacity of metal was in the order $Pb^{2+}$ > $Cu^{2+}$ > $Zn^{2+}$. A high concentration of co-existing ions such as $Ca^{2+}$ and $Mg^{2+}$ depressed the adsorption of heavy metal. Adsorption data showed that metal adsorption on sawdust follows a pseudo-second-order reaction. Kinetic studies also indicated that both surface adsorption and intraparticle diffusion were involved in metal adsorption on sawdust. Column studies prove that sawdust could be effective biosorbent for the removal of heavy metals from aqueous phase.

• Environmental Engineering Research
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• v.11 no.6
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• pp.318-324
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• 2006

The higher valence state of iron i.e., Fe(VI) was employed for the oxidation of one of an important toxic ion, cyanide in the aqueous medium. Cyanide was oxidized into cyanate, which is 1,000 times less toxic to cyanide and often accepted for its ultimate disposal. It was to be noted that Fe(VI) is a very powerful oxidizing agent and can oxidize most of the cyanide within few minutes i.e., ca 5 mins of contact. The data was obtained by the UV-Visible measurements for the Fe(VI) decomposition. The UV-Visible data was used to evaluate the overall rate constant for second order redox reaction between ferrate(VI) and cyanide. Also the pseudo first order rate constant was calculated as keeping the cyanide concentration in excess.

• Advances in environmental research
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• v.5 no.1
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• pp.37-50
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• 2016

The main objective of this study is to evaluate adsorptive removal of Methylene Blue (MB) dye from aqueous solution using pumice powder. The effects of pH, adsorption time, agitation speed, adsorbent dose, and dye concentrations on dye adsorption were investigated. Process kinetics and isotherm model constants were determined accordingly. The results showed that adsorbent dose, dye concentration and agitation speed are the important parameters on dye adsorption and the removal of MB did not significantly change by varying pH. A total adsorption process time of 60 min was observed to be sufficient to effectively remove 50 mg/L MB concentration. The MB adsorption data obeyed both pseudo first order and second order kinetic models. Adsorption of MB by pumice fitted well both Langmiur and Freundlich isotherms ($R^2{\geq}0.9700$), except for 150 rpm agitation speed that system fitted only Langmiur isotherm. The results of this study emphasize that pumice powder can be used as a low cost and effective adsorbent for dye removal.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.141-146
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• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.83-90
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• 2018

In this study, zeolite (Z-C2) was synthesized using a fusion/hydrothermal method on coal fly ash (FA) discharged from a thermal power plant in the Ulsan area and then analyzed via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Z-C2 was characterized in terms of mineralogical composition and morphological analysis. The XRD results showed that its peaks had the characteristics of Na-A zeolite in the range of $2{\theta}$ of 7.18~34.18. The SEM images confirmed that the Na-A zeolite crystals had a chamfered-edge crystal structure almost identical to that of the commercial zeolite. The adsorption kinetics of Cu, Co, Mn and Zn ions by Z-C2 were described better by the pseudo-second-order kinetic model more than by the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model did. The maximum adsorption capacities of Cu, Co, Mn and Zn ions obtained from the Langmuir model were in the following order : Cu (94.7 mg/g) > Co (77.7 mg/g) > Mn (57.6 mg/g) > Zn (51.1 mg/g). These adsorption capacities are regarded as excellent compared to those of commercial zeolite.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.301-309
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• 2021

Chitosan, natural organic polymer, has been applied in water treatment as adsorbent due to non-toxic for human being. The amino group as functional group, can interacts with cation and anion at the same time. The prepared chitosan bead (HCB) was crosslinked to increase chemical stability (HCB-G) and both HCB and HCB-G were prepared to increase physical strength by drying referred to DCB and DCB-G, respectively. The adsorption effect for crosslinking and drying for four types of chitosan bead was tested using pseudo fist order (PFO), pseudo second order (PSO), and intraparticle diffusion model (ID). Regardless of PFO and PSO, the order of K, rate constant, is as followed: HCB > HCB-G > DCB > DCB-G for Cu(II) and phosphate. Drying leading to contraction of bead significantly reduced adsorption rate due to reduce the porosity of chitosan. In addition, crosslingking also negatively effect on adsorption rate. When compared with Cu(II) using hydrogel bead, phosphate showed higher value than Cu(II) for PFO and PSO. The application of ID showed that both hydrogel beads (HCB and HCB-G) obtained a very low R² ranging to 0.37 to 0.81, while R² can be obtained to over 0.9 for DCB and DCB-G, indicting ID is appropriate for low adsorption rate.