• Carbon letters
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• v.4 no.1
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• pp.31-35
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• 2003

The specific adsorption behaviors of activated carbons (ACs) treated with 30 wt% $H_3PO_4$ or NaOH were investigated in the removals of NO or $NH_3$. The acid and base values were determined by Boehm's titration method. And, the surface properties of ACs were studied by FT-IR and XPS analyses. Also, $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET and t-plot methods, respectively. From the adsorption tests of NO and $NH_3$, it was revealed in the case of acidic treatment on ACs that the $NH_3$ removal was more effective due to the increase of acidic functional groups in carbon surfaces. Also, the NO removal was increased, in the case of basic treatment, due to the improvement of basic functional groups, in spite of significant decreases of BET's specific surface area and total pore volume. It was found that the adsorption capacity of ACs was not only determined by the textural characteristics but also correlated with the surface functional groups in the acid-base intermolecular interactions.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.179-184
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• 2011

In this study, several anion exchange membranes were successfully prepared by radiation grafting of vinylbenzyl chloride (VBC) monomer onto a polyethylene-co-tetrafluoroethylene (ETFE) film and subsequent quaternarization with diamins such as 1,4-diazbicyclo[2,2,2]octane, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N',N'-tetramethyl-1,6-diaminohexane, and trimethylamine. The anion exchange capacities of the prepared membranes were determined by using acid-base titration method. The cross-sectional morphology of the membranes was studied by using SEM instrument. The cross-sectional distribution patterns of the grafted polymers with anion exchange functional groups were also studied by EDX analysis.

• Bulletin of the Korean Chemical Society
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• v.21 no.9
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• pp.849-854
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• 2000

The protonation and divalent cation complexation equilibria of several quinolone antibiotics such as nalidixic acid (NAL),flumequine (FLU), oxolinic acid (OXO), ofloxacin (OFL), norfloxacin (NOR) and enoxacin (ENO) have been examined by potentiome tric titration and spectrophotometric method. The antibacterial activity of these drugs depends upon the pH and the concentration of metal cations such as Mg2+ , Ca2+ in solu-tion. The apparent ionization constants of NAL, FLU, OXO, OFL, NOR and ENO in aqueous solution were found to be 6.33, 6.51, 6.72, 7.18, 7.26, and 7.53, respectively. In aqueous solution, NAL, FLU and OXO were found to be present mainly as two chemical species : molecularand anionic; but OFL, NOR and ENO were present mainly as three chemical species : anionic, neutral zwitterionic and cationic form, in equilibrium. The pKa1 and pKa2are found to be 6.10 and 8.28 for OFL; 6.23 and 8.55 for NOR; 6.32 and8.62 for ENO, respec-tively. The complex formation constants between OFL, NOR or FLU and some divalent cations are measured at pH 7.5. The 1 : 1 complexes are formed mainly by ion-dipole interaction. FLU has somewhat larger Kf values than OFL and NOR because its molecular size is small and the FLU is present asanionic form at pH 7.5.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.393-400
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• 2000

2,2￠-Dihydroxyazobenzene (DHAB) was attached to poly(ethylenimine) (PEI) to obtain DHAB-PEI. Spectral titration revealed that uranyl, Fe(III), Cu(II), and Zn(II) ion form 1 : 1-type complexes with DHAB attached to PEI. Formation constants for the metal complexes formed by the DHAB moieties of DHAB-PEI were mea-sured by using various competing ligands. The results indicated thatthe concentrations of uranyl, Fe(III), and Cu(II) ions can be reduced to 10 -16 -10 -23 M at p 8 with DHAB-PEI when the concentration of the DHAB moiety is 1 residue M. By using cyanuric chloride as the coupling reagent, DHAB-PEI was immobilized on Sephadex G-25 resin to obtain DHAB-PEI-Seph. Binding of uranyl,Fe(III), Cu(II), and Zn(II) ion by DHAB-PEI-Seph was characterized by using competing ligands. A new method has been developed for characteriza-tion of metal sequestering ability of a chelating resin. Formation constants and metal-binding capacity of two sets of binding sites on the resin were estimated for each metal ion. DHAB-PI-Seph was applied to recovery of metals such as uranium,Fe, Cu, Zn, Pb, V, Mn, and W from seawater. The uranium recovery from seawaterby DHAB-PEI-Seph does not meet the criterion for economical feasibility partlydue to interference by Fe and Zn ions. The seawater used in the experiment was contaminated by Fe and Zn and, therefore, the efficiency of uranium extractionfrom seawater with DHAB-PEI-Seph could be improved if the experiment is carried out in a cleaner sea.

• Journal of Industrial Technology
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• v.42 no.1
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• pp.7-12
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• 2022

High nickel layered oxide cathodes are gaining increasing attention for lithium-ion batteries due to their higher energy density and lower cost compared to LiCoO₂. However, they suffer from the formation of residual lithium on the surface in the form of LiOH and Li₂CO₃ on exposure to ambient air. The residual lithium causes notorious issues, such as slurry gelation during electrode preparation and gas evolution during cell cycling. In this review, we investigate the residual lithium issues through its impact on cathode slurry instability based on deformed polyvinylidene fluoride (PVdF) as well as its formation and reduction mechanism in terms of inherently off-stoichiometric synthesis of high nickel cathodes. Additionally, new analysis method with anhydrous methanol was introduced to exclude Li⁺/H⁺ exchange effect during sample preparation with distilled water. We hope that this review would contribute to encouraging the academic efforts to consider practical aspects and mitigation in global high-energy-density lithium-ion battery manufacturers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.427-438
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• 2023

Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acid-base titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.

• Korean Journal of Veterinary Service
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• v.23 no.4
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• pp.349-360
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• 2000

An epidemiological survey was conducted to investigate fowl typhoid outbreaks in Kyungnam province of Korea. The causative agent, salmonella gallinarum was isolated from 68 chicken samples of tentatively diagnosed fowl typhoid cases occurred during the period from January 1996 to September 1999. Comparative studies were also carried out to evaluate the diagnostic methods for detection of S gallinam The results obtained were as follows; 1. Of the 68 cases of tentatively diagnosed fowl typhoid, 56 (82%) cases were determined as fowl typhoid by biochemical test and pathological findings. The other 12 (18%) cases were determined as paratyphoid. 2. Fowl typhoid outbreaks occur continuously all seasons in the year, however the incidence was remarkably increased from May to September. 3. The frequency of incidence of fowl typhoid in terms of regional distribution was relatively high in egg-laying hens facilities, and the mode of transmission is likely to be either egg-to-egg or lateral transfer by wild birds or rats. 4. All of 18 isolates from 56 cases were identified as S gallinarum by biochemical and serological test. 5. Antimicrobial drug susceptibility test against 18 isolates showed that the isolates were highly susceptible to ASH, CZ, CF and GM (above 90%), whereas those strains were 100% resistant to EM, NA and PC. 6. S gallinarum rfbS gene was targeted to be amplified by PCR for comparative detection of S gallinarum in the experimentally infected chickens. The amplified 720bp DNA fragment, which is specific in D serogroup strains of S enterica subspecies was confirmed by agarose gel electrophoresis. 7. A comparison made between fecal culture and PCR-method revealed that later-method was relatively higher in detection rate than that of former method for S gallinarum. 8. Comparison of currently applied methods, rapid serum agglutination test (RST) and microplate agglutination test (MAT), with experimentally infected chickens were made to evaluate sensitivity of detection by neutralizing antibody titration. Both methods detected neutralizing antibodies from the challenged chickens of 5 day post infection. However, positive reactions were determined after 7 and 9 days post infection by MAT and RST, respectively.

• Macromolecular Research
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• v.12 no.4
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• pp.367-373
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• 2004

We have developed a rigorous heat treatment method to improve the biocompatibility of chitosan as a tissue-engineered scaffold. The chitosan scaffold was prepared by the controlled freezing and lyophilizing method using dilute acetic acid and then it was heat-treated at 110$^{\circ}C$ in vacuo for 1-3 days. To explore changes in the physicochemical properties of the heat-treated scaffold, we analyzed the degree of deacetylation by colloid titration with poly(vinyl potassium sulfate) and the structural changes were analyzed by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffractometry (WAXD), and lysozyme susceptibility. The degree of deacetylation of chitosan scaffolds decreased significantly from 85 to 30% as the heat treatment time increased. FT-IR spectroscopic and WAXD data indicated the formation of amide bonds between the amino groups of chitosan and acetic acids carbonyl group, and of interchain hydrogen bonding between the carbonyl groups in the C-6 residues of chitosan and the N-acetyl groups. Our rigorous heat treatment method causes the scaffold to become more susceptible to lysozyme treatment. We performed further examinations of the changes in the biocompatibility of the chitosan scaffold after rigorous heat treatment by measuring the initial cell binding capacity and cell growth rate. Human dermal fibroblasts (HDFs) adhere and spread more effectively to the heat-treated chitosan than to the untreated sample. When the cell growth of the HDFs on the film or the scaffold was analyzed by an MTT assay, we found that rigorous heat treatment stimulated cell growth by 1.5∼1.95-fold relative to that of the untreated chitosan. We conclude that the rigorous dry heat treatment process increases the biocompatibility of the chitosan scaffold by decreasing the degree of deacetylation and by increasing cell attachment and growth.

• Journal of Soil and Groundwater Environment
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• v.29 no.1
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• pp.1-9
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• 2024

As part of monitoring technology aimed at verifying the stability of CO₂ geologic storage and mitigating concerns about leakage, a method for measuring the pH and alkalinity of high-pressure fluid samples was established to obtain practical technology. pH measurement for high-pressure samples utilized a high-pressure pH electrode, and alkalinity was measured using the Gran titration method for samples collected with a piston cylinder sampler (PCS). Experimental samples, referencing CO₂-rich water and CO₂ geologic storage studies, were prepared in the laboratory. The PCS controls the piston, preventing CO₂ degassing and maintaining fluid pressure, allowing mixing with KOH to fix dissolved CO₂. Results showed a 6.1% average error in high-pressure pH measurement. PCS use for sample collection maintained pressure, preventing CO₂ degassing. However, PCS-collected sample alkalinity measurements had larger errors than non-PCS measurements, limiting PCS practicality in monitoring field settings. Nevertheless, PCS could find utility in preprocessing for carbon isotope analysis and other applications. This research not only contributes to the field of CCS monitoring but also suggests potential applications in studies related to natural analogs of CCS, CO₂-rock interaction experiments, core flooding experiments, and beyond.

• Journal of Energy Engineering
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• v.14 no.4 s.44
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• pp.219-225
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• 2005

for the removal of carbon dioxide in flue gas, which is the main cause of the global warming, chemical absorption methods were widely used for years. Alkanolamines such as MEA, AMP, MDEA are mainly used as an absorbent. In this study, cyclic amines - Piperazine, Piperidine and Cyclohelylamine are investigated to compare the chemical solubilities, absorption capacities and rate ot reaction. In conclusion, Piperazine is the most effective absorbent of $CO_2$ and ran be the excellent alternative to the former absorbents. Experiments were performed at 5, 10, 15 weight percent, 30, 40, $50^{\circ}C$, and the gas solubilities are determined by back-titration method, and using Gas Chromatography the absorption rate was compared.