• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.36-42
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• 2005

This study examined the feasibility of producing sulfuric acid and ammonia water from ammonium sulfate solution using two-compartment electrodialysis with a bipolar membrane (EDBM). Electrodialysis experiments were carried out with 20 wt% ammonium sulfate at different current densities and sulfuric acid concentrations in a concentrate compartment. The current efficiency increased with the current density from 25 to $100\;mA/cm^2$. Nevertheless, the efficiency was relatively low compared with that of general desalting electrodialysis, owing to the diffusion of sulfuric acid from the concentrate compartment to the diluate. The diffusion rate through the anion exchange membrane increased with the sulfuric acid concentration in the concentrate compartment, which decreased the current efficiency. Conversely, the electrical resistance decreased with increasing current density owing to the Joulian heat generated during water dissociation in the transition region of the bipolar membrane under a high electric field. From the experimental results, we concluded that operating at a higher current density is effective from the perspective of current efficiency and electrical resistance when producing sulfuric acid and ammonia water from ammonium sulfate using a two-compartment EDBM process. Further studies on the effects of increasing the sulfuric acid concentration on current efficiency are required to apply the EDBM process practically.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.623-628
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• 1985

Rate constants for complexing with thiocyanate after ring opening of molybdenum-oxalate in acid media were obtained spectrophotometrically at 460nm. The acid-assisted dissociation of molybdenum-oxalate and the reaction of thiocyanate with oxalatooxomolybdenum (V) complex in acid media were investigated with thiocyanate and hydrogen ion concentration. The kinetic data indicate that molybdenum-oxalate is protonated to a limited extent in acid media and the protonated complex is responsible for an increase in rate for the reaction of thiocyanate with oxalatooxomolybdenum (V) complex. Replacement of an oxalate ligand in acid media has been interpreted in terms of dissociative mechanism involving bond-breaking of the oxygen trans to the yl oxygen.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.745-750
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• 2007

An isotope dilution-liquid chromatography/tandem mass spectrometric method was developed as a candidate reference method for the accurate determination of folic acid in infant milk formula. Sample was spiked with 13C5-folic acid and then extracted with phosphate buffer (pH 6) solution. The extract was further cleaned up by deproteinization followed by a C18 solid-phase extraction cartridge. The extract was analyzed by using LC/ ESI/MS/MS with selectively monitoring the collisionally induced dissociation channels of m/z 442 → m/z 295 and m/z 447 → m/z 295, which are the neutral glutamyl loss from the [M+H]+ ions of folic acid and 13C5-folic acid, respectively. LC/MS/MS chromatograms showed substantially reduced background from chemical noises compared to LC/MS chromatograms. Repeatability and reproducibility studies showed that the LC/MS/ MS method is a reliable and reproducible method which can provide less than 1.5 relative percentage of method precision.

• Food Science of Animal Resources
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• v.30 no.6
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• pp.946-950
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• 2010

This study evaluated the antimicrobial effects of meat processing-related organic acids on Burkholderia thailandensis (Burkholderia pseudomallei surrogate) with different water activities. B. thailandensis KACC12027 (4 log CFU/mL) was inoculated in microwell plates containing tryptic soy broth pH-adjusted to 4, 5, 6, and 7 with ascorbic acid, citric acid, and lactic acid and with water activities adjusted to 0.94, 0.96, 0.98, and 1.0 with NaCl, followed by incubation at $35^{\circ}C$ for 30 h. The optical density (OD) of the samples was measured at 0, 3, 6, 12, 24, and 30 h at 595 nm to estimate the growth of B. thailandensis. Growth of B. thailandensis was observed only at water activity of 1.0. In general, more bacterial growth (p<0.05) was observed at pH 6 than at pH 7, and the antimicrobial effects of the organic acids on B. thailandensis were in the following order: Ascorbic acid > lactic acid > citric acid after incubation at $35^{\circ}C$ for 30 h. These results indicate that organic acids in meat processing-related formulations should be useful in decreasing the risk related to an emerging high risk agent (B. pseudomallei).

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.168-170
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• 2010

• Journal of Environmental Science International
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• v.21 no.4
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• pp.421-435
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• 2012

Novel $N_2O_2$ tetradentate ligands, H-3BPD and H-2BPD were synthesized. Hydrochloric acid salts of Br-3BPD, Cl-3BPD, Br-2BPD and Cl-2BPD having Br and Cl substituents at the $para$ position of the phenol hydroxyl group, were synthesized. The ligands were characterized by C. H. N atomic analysis, $^1H$ NMR, $^{13}C$ NMR, UV-visible, and mass spectra. The proton dissociation constants ($logK_n{^H}$) of the phenol hydroxyl group and secondary amine of the synthesized $N_2O_2$ ligands were shown by four step wise values. The orders of the calculated overall proton dissociation constants ($log{\beta}_p$) were Br-3BPD < Cl-3BPD < H-3BPD in case of 3BPD and Br-2BPD < Cl-2BPD < H-2BPD in case of 2BPD respectively. The order agreed well with that of $para$ Hammett substituent constants(${\delta}_p$). The stability constants($logK_{ML}$) of the complexes between the synthesized ligands and transition metal(II) ions agreed with the order of $log{\beta}_p$ of the ligands. The order of the $logK_{ML}$ value of the each transition metal (II) ion was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II), which agreed well with that of Iriving-Williams series.

• Journal of Environmental Science International
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• v.19 no.7
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• pp.849-860
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• 2010

A new $N_3O_2$ pentadentate ligand, N,N'-Bis(2-hydroxybenzyl)-ethylenetriamine(H-BHET 3HCl) was synthesized. The hydrochloric acid salts of Br-BHET 3HCl, Cl-BHET 3HCl, $CH_3O$-BHET 3HCl and $CH_3$-BHET 3HCl containing Br-, Cl-, H-, $CH_3O-$ and $CH_3-$ groups at the para-site of the phenol group of the H-BHEP were synthesized. The structures of the ligands were confirmed by C. H. N. atomic analysis and $^1H$ NMR, $^{13}C$ NMR, UV-visible and mass spectra. The calculated stepwise protonation constants(${\logK_n}^H$) of the synthesized $N_3O_2$ ligands showed six steps of the proton dissociation. The orders of the overall protonation constants($\log{\beta}_p$) of the ligands were Br-BHET < Cl-BHET < H-BHET < $CH_3O$-BHET < $CH_3$-BHET. The orders agreed well with that of para Hammett substituent constants(${\delta}_p$). The calculated stability constants($\logK_{ML}$) between the ligands and heavy metal ions (Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II)) agreed well with the order of the overall proton dissociation constants of the ligands but they showed a reverse order in para Hammestt substituent constants(${\delta}_p$). The order of the stability constants between the heavy metal ions with the synthesized ligands were Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II).

• Journal of Environmental Science International
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• v.18 no.7
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• pp.735-746
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• 2009

Hydrochloric acid salt of a new $N_2O_3$ pentadentate ligand, N,N'-Bis(2-Hydroxybenzyl)-1,3-diamino-2-propanol(H-BHDP 2HCl) was synthesized. Br-BHDP 2HCl, CI-BHDP 2HCl, $CH_3-BHDP$ 2HCl and $CH_3O$-BHDP 2HCl having Br, Cl, $CH_3$ and $CH_3O$ substituents at 5-position of the phenol group of H-BHDP 2HCl were also synthesized. The potentiometry study in aqueous solution revealed that the proton dissociations of the synthesized ligands occurred in four steps and their order of the calculated overall proton dissociation constants($log{\beta}_p$) was Br-BHDP < Cl-BHDP < H-BHDP < $CH_3O-BHDP$ < $CH_3-BHDP$. The order showed a similar trend to that of Hammett substituent constants(${\delta}_p$). The order of the stability constants($logK_{ML}$) was Co(II) < Ni(II) < Cu(II) < Zn(II) < Cd(II) < Pb(II). The order in their stability constants ($logK_{ML}$) of each transition metal complex agreed with that of the overall proton dissociation constants ($log{\beta}_p$).

• Journal of Environmental Science International
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• v.15 no.8
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• pp.799-809
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• 2006

Hydrobromic acid salts of new N, N, O tridentate ligands containing phenol, 2-[(2-Methylamino- ethyl- amino)-methyl]-phenol(H-MMP. 2HBr), 5-Bromo-2-[(2-Methylamino-ethylamino)-methyl]-phenol (Br- MMP. 2HBr), 5-Chloro-2-[(2-Methylamino-ethylamino)-methyl]-phenol(Cl-MMP. 2HBr), 5-Methyl-2-[(2-Methylamino-ethylamino)-methyl]-phenol(Me-MMP. 2HBr), 5-Methoxy-2-I(2-Methylamino-ethylamino)- methyl]-phenol(MeO- MMP. 2HBr) and. 1-[(2-Methylamino-ethylamino)- methyl]-naphthalen-2-ol(Nap- MMP. 2HBr) were synthesized. The synthesized ligands were confirmed by C. H. N. atomic analysis, UV-visible and IR spectroscopies, $^1$H NMR, $^{13}$C NMR and mass analysis. The potentiometry study revealed that the proton dissociation constants(logK$_n^H$) of the synthesized ligands and stability constants (logK$_{ML}$, logK$_{LM2}$) of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions occurred in three steps and the order of the calculated overall proton dissociation constants(log$\beta_p$) and stability constants (logK$_{ML}$) of ligands was Br-MMP. 2HBr < Cl-MMP 2HBr < H-MMP. 2HBr < Nap-MMP. 2HBr < Me-MMP. 2HBr < MeO-MMP. 2HBr. The order showed a similar trend to that of Hammett substituent constants($\delta_p$). The synthesized ligands usually form 2:1(ML$_2$) complexes with transition metal ions. The order of the stability constants of each transition metal ions was Co(II) < Ni(II) < Cu(II) ;> Zn(II) ;> Cd(II) ;> Pb(II).

• Journal of Environmental Science International
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• v.16 no.8
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• pp.913-920
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• 2007

Hydrochloride acid salts of new $N_2O_2$ tetradentate ligands containing amine and phenol N,N'-bis(2-hydroxybenzyl)-o-phenylenediamine(H-BHP), N,N'-bis(5-bromo-2-hydroxybenzyl)-o-phenylenediamine(Br-BHP), N,N'-bis(5-chloro-2-hydroxybenzyl)-o-phenylene-diamine(Cl-BHP), N,N'-bis(5-methyl-2-hydroxybenzyl)-o-phenylene-diamine (Me-BHP) and N,N'-bis(5-methoxy-2-hydroxybenzyl)-o-phenylenediamine(MeO-BHP) were synthesized. The ligands were characterized by elemental analysis, mass and NMR spectroscopy. The elemental analysis showed that the ligands were isolated as dihydrochloride salt. The potentiometry study revealed that the proton dissociation constants$(logK_n{^H})$ of ligands and stability constants $(logK_{ML})$ of transition and heavy metals complexes. The order of the stability constants of each metal ions for ligands was Br-BHP < Cl-BHP > H-BHP < MeO-BHP < Me-BHP.