• Membrane and Water Treatment
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• v.14 no.4
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• pp.163-173
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• 2023

The presence of high amounts of organic and inorganic contaminants in textile wastewater is a major environmental concern. Therefore, the treatment of textile wastewater is an urgent issue to save the aquatic environment. The disposal of large quantities of untreated textile wastewater into inland water bodies can cause serious water pollution. In this study, synthetic dye wastewater samples were prepared using orange dye in the laboratory. The synthetic samples were then treated by a batch adsorption process using the prepared activated carbon (AC) from date pits. The wastewater parameters studied were the pH, total dissolved solids (TDS), total suspended solids (TSS), electrical conductivity (EC) and salinity. The activated adsorption process showed that the maximum removal efficiencies of electric conductivity (EC), salinity, TDS and TSS were 65%, 92%, 89% and 90%, respectively. The removal efficiencies were proportional to the increase in contact time (30-120 min) and AC adsorbent dose (1, 3 and 5 g/L). The adsorption profile indicates that 5 g/L of adsorbent delivers better results for TDS, EC, TSS and salinity at contact time of 120 min. The adsorption characteristics are better suited to the pseudo-second-order kinetic model than to the pseudo-first-order kinetic model. The Langmuir and Freundlich isotherms were well suited for describing the adsorption or contact behavior of EC and TSS within the studied system.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.475-482
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• 1986

Rates and equilibriurn of complex formation between $Ni^{2+}$ and D-penicillamine have been investigated in aqueous solutions. Kinetic study on the complex formation were performed in the pH range of 8∼9 by the use of pressure-jump technique. D-Penicillamine coordinates to the nickel(II) ion utilizing sulfur and nitrogen as donor atoms in the high pH condition (pH 9.2). However, in the pH range of 8.25∼9.07, the stepwise stability constant becomes drastically reduced and the undissociated mercapto group does not participate in bonding. The rate-determining step of the complexation reaction is found to be the release of a water molecule from the inner-coordination sphere of $Ni^{2+}$ ion.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.258-264
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• 2012

Purpose: This review aims at introducing 3 modeling approaches classified into 3 categories based on the purpose (estimation or prediction), structure (linear or non-linear) and phase (steady-state or dynamic-state); 1) statistical approaches, 2) kinetic modeling and 3) mechanistic modeling. We hope that this review can be a useful guide in the model-based approach of calcium metabolism as well as illustrates an application of engineering tools in studying biosystems. Background: The meaning of biosystems has been expanded, including agricultural/food system as well as biological systems like genes, cells and metabolisms. This expansion has required a useful tool for assessing the biosystems and modeling has arisen as a method that satisfies the current inquiry. To suit for the flow of the era, examining the system which is a little bit far from the traditional biosystems may be interesting issue, which can enlarge our insights and provide new ideas for prospective biosystem-researches. Herein, calcium metabolic models reviewed as an example of application of modeling approaches into the biosystems. Review: Calcium is an essential nutrient widely involved in animal and human metabolism including bone mineralization and signaling pathways. For this reason, the calcium metabolic system has been studied in various research fields of academia and industries. To study calcium metabolism, model-based system analyses have been utilized according to the purpose, subject characteristics, metabolic sites of interest, and experimental design. Either individual metabolic pathways or a whole homeostasis has been modeled in a number of studies.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.150-155
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• 1998

Kinetic studies on the reaction of isoquinoline with para-substituted benzylbromides were conducted under various pressures (1 ~1000 bar) in acetonitrile. From the rate constants obtained, the activation parameters such as$\DeltaV^{\neq}, \Delta\beta^{\neq}, \DeltaH^{\neq}, \DeltaS^{\neq}, \DeltaG^{\neq}$ and Ea were evaluated. Reaction rate increasing the pressure and temperature. The activation compressibility coefficient and the activation entropy showed negative values. From the substituent effect and the results, it was found that the reaction proceeds through $S_N2$ mechanism, but the structure of transition state was slightly changed with substituents and pressure.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.792-799
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• 1994

The spectral changes of 3,3'-diethyl oxacarbocyanine(DOC) in the aqueous solution and in the presence of polyacrylic acid(PAA) were studied by means of absorption and fluorescence spectroscopy. The spectral change of DOC in the aqueous solution with concentration changes is attributed to the formation of dimer. In the presence of PAA, the characteristic changes of metachromatic band with changes of P/D (the ratio between available binding site and the dye concentration) are found and the discussions are made in terms of stacking theory. A kinetic study of the interaction between DOC and PAA was also investigated by the absorption and fluorescence stopped-flow spectroscopy. The observed relaxation effect in PAA-DOC system can be described quantitatively by assuming two relaxation processes occur.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.592-599
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• 2018

An increase in the global production of biodiesel has resulted in the newfound significance of its byproduct, glycerol. The synthesis of acetins is an economical avenue to enhance the value of glycerol derived from biodiesel. WE developed an eco-friendly process for the synthesis of fuel additives from glycerol using a mixed oxide $SO{_4}^{2-}/CeO_2-Al_2O_3$ as catalyst. The $CeO_2-Al_2O_3$ mixed oxide was synthesized by the combustion method and then sulfated. The characterization of the catalyst was by means of XRD, BET, FTIR, and SEM. The influence of temperature, mole ratio and catalyst loading on yield and selectivity of the acetins was studied for the esterification of glycerol. The reaction rate constants ($k_1$, $k_2$ and $k_3$) were estimated using optimization method in MAT lab, and the activation energies ($E_1$, $E_2$ and $E_3$) were determined by the Arrhenius equation. Furthermore, a kinetic model was developed.

• Applied Biological Chemistry
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• v.21 no.2
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• pp.112-118
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• 1978

Xanthine oxidase from bovine thyroid glands was purified to apparent homogeneity when judged by analytical disc gel electrophoresis. The purification procedures include pancreatin digestion, butanol extraction, ammonium sulfate precipitation, calcium phosphate gel adsorption, ultrafiltration, calcium phosphate gel-cellulose column chromatography, gel filtration, preparative Sephadex G-25 column electrophoresis, and preparative polyacrylamide gel electrophoresis. The enzyme was enriched 1,000-fold. However, its specific activity was markedly low as compared with highly purified milk enzyme. Thyroidal xanthine oxidase exhibited a low specificity for substrates and electron acceptors. The kinetic properties of thyroid xanthine oxidase were found to be similar to those of the milk enzyme on the basis of Michaelis constants for common substrates.

• Transactions of the Korean hydrogen and new energy society
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• v.4 no.1
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• pp.11-19
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• 1993

The kinetic studies of the hydrogen induced amorphization in $ErCo_2$ Laves phase is observed by the internal standard method using X-ray diffraction intensities. The activation energy and rate constant exponent for the amorphization in $ErCo_2$ are found to be 26 kcal/mole and 0.78, respectively. From these results, it is believed that the mechanism of the hydrogen induced amorphization in $ErCo_2$ is related to the motion of Co atoms. Though there are many similar physical properties between $ErCo_2$ and $ErNi_2$, the activation energy for the amorphizatin in $ErCo_2$ is larger than that in $ErNi_2$ and the amorphization rate in $ErCo_2$ is slower. It is suggested that these differences of activation energy for the hydrogen induced amorphization and the amorphization rate between $ErCo_2$ and $ErNi_2$ is due to the occurence of structural change on forming crystalline hydride.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.1
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• pp.23-34
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• 2004

Escherichia coli transcription termination factor Rho catalyzes the unwinding of RNA/DNA duplex in reactions that are coupled to ATP binding and hydrolysis. Fluorescence stopped-flow methods using ATP and the fluorescent 2'(3')-O-( N-methylanthraniloyl) derivatives (mant-derivatives) of ATP and ADP were used to probe the kinetics of nucleotide binding to and dissociation from the Rho-RNA complex. Presteady state nucleotide binding kinetics provides evidence for the presence of negative cooperativity in nucleotide binding among the multiple nucleotide binding sites on Rho hexamer. The binding of the first nucleotide to the Rho-RNA complex occurs at a bimolecular rate of 3.6${\times}$10$\^$6/ M$\^$-1/ sec$\^$-1/ whereas the second nucleotide binds at a slower rate of 4.7${\times}$10$\^$5/ M$\^$-1/ sec$\^$-1/ at 18$^{\circ}C$, RNA complexed with Rho affects the kinetics of nucleotide interaction with the active sites through conformational changes to the Rho hexamer, allowing the incoming nucleotide to be more accessible to the sites. Adenine nucleotide binding and dissociation is more favorable when RNA is bound to Rho, whereas ATP binding and dissociation step in the absence of RNA occurs significantly slower, at a rate ∼70- and ∼40-fold slower than those observed with the Rho-RNA complex, respectively.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1897-1901
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• 2011

This report shows the rates of solvolyses for phenyl methanesulfonyl chloride ($C_6H_5CH_2SO_2Cl$, I) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Three representative solvents, studies were made at several temperatures and activation parameters were determined. The thirty kinds of solvents gave a reasonably precise extended Grunwald-Winstein plot, coefficient (R) of 0.954. The sensitivity values (l = 0.61 and m = 0.34, l/m = 1.8) of phenyl methanesulfonyl chloride (I) were smaller than those obtained for benzenesulfonyl chloride ($C_6H_5SO_2Cl$, II; l = 1.01 and m = 0.61) and 2-propanesulfonyl chloride ($(CH_3)_2CHSO_2Cl$, III; l = 1.28 and m = 0.64). As with the two previously studied solvolyses, an $S_N2$ pathway with somewhat ionization reaction is proposed for the solvolyses of I. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were determined and they are also in line with values expected for a bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.34 in $CH_3OH/CH_3OD$ is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.