• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.430-438
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• 2008

The experiments for separation and recovery of CO$_2$ were conducted by aqueous sodium glycinate solution, which is one of the amino acid salts, as an absorbent of CO$_2$ in this study. Absorption capacities of aqueous MEA and sodium glycinate solution according to partial pressure of CO$_2$ were evaluated by vapor-liquid equilibrium tests of 20 wt% and 30 wt% above-mentioned absorbents, respectively. In addition, the pilot scale(2 t-CO$_2$/day) experiments based on prior results were carried out. As a result, CO$_2$ removal efficiency of aqueous sodium glycinate solution was lower than that of aqueous MEA solution. This phenomenon means that CO$_2$ removal efficiency of aqueous sodium glycinate solution mainly depends on its molecular structure. Consequently, the first application of certain amino acid salt, as an absorbent of CO$_2$, to pilot plant of 2 t-CO$_2$/day scale was carried out in our country.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.324-329
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• 2005

The efficiency of reducing nitric oxide using urea combined with alkali salt additives is reported in this study. The inlet concentration of NO is 500 ppm with air flow rates of 3 and 5 L/min. Reduction of NO was studied from 650 to $1,050^{\circ}C$ with urea concentrations of 0.3 to 1 mol/L. The efficiency for the reduction of NO increased by 44% when urea is added alone. A further increase in efficiency was observed in the presence of NaOH as additive in fact, the efficiency was increased by more than 25% and 75% when 0.5 mol/L and 1 mol/L NaOH were added with the urea. The efficiency for the reduction of NO increased with all additives, but descended in the order NaOH, $Na_2CO_3$, $NaNO_3$, HCOONa, and CHCOONa. The maximum efficiency of NaOH and $Na_2NO_3$ are 74% and 73%, respectively. All these additives did not alter the comparatively wide operating temperature window for reducing NO. However, sodium compounds do not shift the maximum NO concentration towards lower temperatures when the NO removal activity enhances.

• Membrane Journal
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• v.34 no.3
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• pp.182-191
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• 2024

This review addresses the pressing need for effective wastewater treatment methodologies by exploring advanced thin-film nanocomposite (TFN) nanofiltration membranes aimed at efficient dye removal from industrial effluents. Utilizing insights from recent research, the review focuses on the fabrication of TFN membranes incorporating innovative materials such as nanocarbons, silica nanospheres, metal-organic frameworks (MOFs), and MoS₂. The primary goals are to enhance dye removal efficiency, improve antifouling properties, and maintain high selectivity for dye/salt separation. By leveraging the distinct advantages of these nanomaterials-including large surface areas, mechanical robustness, and specific pollutant interaction capabilities-this review aims to overcome the limitations of current nanofiltration technologies and provide sustainable solutions for water treatment challenges.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.201-212
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• 2002

The objective of this study was to investigate the treatment efficiency, kinetics, and morphological characteristics of biofilm in upflow $Biobead^{(R)}$ process, a kind of biological aerated filter(BAF). The $Biobead^{(R)}$ system showed high removal rates of $COD_{Mn}$(76~83%), $BOD_5$(67~88%) and SS(71~91%) for food wastewater with high salt concentration ($>4,000mg/{\ell}$) under short reaction times(2~3hrs). Even at aerobic condition, the system had high treatment efficiency for both T-N (51~63%) and T-P(62~81%). The removal kinetics of $COD_{Mn}$, $BOD_5$, T-N, T-P, and $Cl^-$ in the $Biobead^{(R)}$ system showed a plug-flow pattern with reaction rate constants($hr^{-1}$) of 0.58, 0.63, 0,30, 0.48, and 0.38 respectively. A backwashing process to remove excess biomass and filtered solids was needed at least once during 22-hour operation at $0.5kg\;BOD\;m^{-3}{\cdot}d^{-1}$ loading. At the higher loading($1.0kg\;BOD\;m^{-3}{\cdot}d^{-1}$) the backwashing interval was shorten by 8 hours. The COD, BOD, T-N, and T-P were removed from 43 to 66% only by aerobic biodegradation. The SS was removed over 70% by the filtering of $Biobead^{(R)}$ media in the treatment system. The first one of three serial Biobead reactors showed the highest removal values for $COD_{\alpha}$(52.3%), $COD_{Mn}$(38.8%), BOD(62.5%), and T-N(40.0%). The SS and T-P had the highest removal values(47.5% and 29.2%) at the second one of the serial reactors. The biofilm had non-homogeneous spatial distribution and the colonies were embedded in the sunk area of the Biobead. The thickness of the biofilm was very thin ($5.0{\sim}29.4{\mu}m$) compared to the biofilm thickness($200{\sim}300{\mu}m$) used in other BAF systems.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.709-716
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• 2011

Effect of inorganic coagulants dosing on the performance of electro-chemical process was studied when treating hospital wastewater having low electrolyte concentration. It is thought that adding inorganic coagulants caused increase in concentration of electrolyte and this caused increase in free chloride concentration and consequently, caused increase in indirect oxidation effect. Thus, COD removal efficiencies more than doubled in percentage terms at the 2 hrs of reaction time and current density of $1.76A/dm^2$ compared with the results obtained from the parallel experiments without adding inorganic coagulants. T-N removal efficiencies approximately doubled in percentage terms at the 2 hrs of reaction time and 700 ppm of coagulants addition and applied current density of $1.76A/dm^2$ due to the increase of free residual chlorine such as HOCl caused by increase of electrolyte concentration through the addition of inorganic coagulants. Under the same experimental condition, more than 90% of T-P removal efficiencies was obtained. The reason can be explained that increase of chemical adsorption rate between phosphate and insoluble metal compounds caused by dissolved oxygen generated from anode by the increased electrolyte concentration through inorganic coagulants addition make a major role in improving T-P removal efficiencies. It can be concluded that inorganic coagulants addition as the supplemental agent of electrolyte is effective way in improving organic and nutrient salt removal efficiency when treating hospital wastewater having low electrolyte concentration.

• Membrane Journal
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• v.4 no.3
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• pp.163-170
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• 1994

The separation of inorganic salt from amino acid solution using was performed electrodialysis. In order to review the availability of electrodialysis using isoelectric point of amino acid as a bio-separation technique, electrodialysis stacks were designed using ion exchange membrane. Separation of NaCl from amino acid solution was performed in the condition similar to amino acid fermentation process. To obtain otimum conditions of separation, leakage of amino acid depending of pH and limiting current density were measured. On the basis of optimum condition, removal of NaCl and leakage of amino acid were investigated quantitatively in batch and continuous process, and current efficiencies were also obtained. As a result of batch experiment for 11 hours each amino acid solution, removal efficiencies of NaCl were in the ranges of 96.1~96.2%. Amino acid leakage rate of glycine, methionine, alanine were 2.5, 1.7, 2.0% respectively. Current efficiencies were in the ranges of 44.5~44.6%. As a result of continuous experiment in various flow rate of each amino acid solution, it took 120 ~ 150 min to reach to steady state. Removal efficiency of NaCl was increased as the flow rate was decreased, but current efficiency was decreased. At the steady states, there were no leakage of amino acid.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.173-187
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• 2015

The goal of present work is the preparation of a novel positively charged nanofiltration (NF) membrane and its development for the cation removal of aqueous solutions. This NF membrane was fabricated by the surface modification of polysulfone (PSf) ultrafiltration support. The active top-layer was formed by interfacial cross-linking polymerization of poly(ethyleneimine) (PEI) with p-xylylene dichloride (XDC) and then quaternized with methyl iodide to form a perpetually positively charged layer. In order to improve the efficiency of nanofiltration membrane, the concentration of PEI, XDC and methyl iodide solutions, PEI coating and cross-linking time have been optimized. As a result, a high water flux and high $CaCl_2$ rejection (1,000 ppm) was obtained for the composite membrane with values of $18.29L/m^2.h$ and 93.62% at 4 bar and $25^{\circ}C$, respectively. The rejections of NF membrane for different salt solutions followed the order of $Na_2SO_4$ < $MgSO_4$ < NaCl < $CaCl_2$. Molecular weight of cut off (MWCO) was calculated via retaining of PEG solutions with different molecular weights that finally, it revealed the Stokes and hydrodynamic radius of 1.457 and 2.507 nm on the membrane selective layer, respectively. The most efficient positively charged nanofiltration membrane exhibited a $Ni^{2+}$ rejection of 96.26% for industrial wastewater from Shamse Hadaf Co. (Kashan, Iran).

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1629-1635
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• 2019

Azo dyes are recalcitrant pollutants, which are toxic, carcinogenic, mutagenic and teratogenic, that constitute a significant burden to the environment. The decolorization and the mineralization efficiency of Remazol Brillant Orange 3R (RBO 3R) was studied using a probiotic consortium (Lactobacillus acidophilus and Lactobacillus plantarum). Biodegradation of RBO 3R (750 ppm) was investigated under shaking condition in Mineral Salt Medium (MSM) solution at pH 11.5 and temperature $25^{\circ}C$. The bio-decolorization process was further confirmed by FTIR and UV-Vis analysis. Under optimal conditions, the bacterial consortium was able to decolorize the dye completely (>99%) within 12 h. The color removal was 99.37% at 750 ppm. Muliplex PCR technique was used to detect the Lactobacillus genes. Using phytotoxicity, cytotoxicity, mutagenicity and biototoxicity endpoints, toxicological studies of RBO 3R before and after biodegradation were examined. A toxicity assay signaled that biodegradation led to detoxification of RBO 3R dye.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.4 no.2
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• pp.51-56
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• 2018

Azeotropic drying process is routinely applied to enhance nucleophilicity of $[^{18}F]$fluoride ion during the nucleophilic production of PET radiotracers; however, the drying process requires usually 15-25 min. Due to the high demand of employing fluorine-18 ($t_{1/2}=109.8min$) in PET radiopharmaceutical production, several research groups have focused on the method development, obviating tedious removal process of the residual target water ($[^{18}O]H_2O$) for $[^{18}F]$fluoride ion complex to be used in radiofluorination. Some development in radiofluorination in a mixed organic solvent system was demonstrated with various aliphatic substrates, but only kryptand as a phase transfer agent was utilized in the reported method. Here, we extend to investigate the development scope of applicability with basic alkyl ammonium salt as a phase transfer agent through the extensive elution efficiency study and radiofluorination outcome for aliphatic radiofluorination.

• Membrane Journal
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• v.27 no.3
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• pp.240-247
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• 2017

In this study, the heterogeneous ion exchange membranes prepared by the combination of the carbon electrode and mixed the cation and anion exchange polymers and polyvinylidene fluoride as the basic polymer together were made to recognize the efficiency of the salt removal for the application of the membrane capacitive deionization process. The mixing weight ratio of the solvent, basic polymer and ion exchange resin was 7 : 2 : 1 and this mixed solution was directly cast on the electrode. As for the operating conditions of the adsorption voltage and time, feed flow rate, desorption voltage and time of the feed solution NaCl 100 mg/L, the salt removal efficiencies (SRE) were measured. Apart from this NaCl, the $CaCl_2$ and $MgSO_4$ solutions were investigated in terms of SRE as well. Typically, SRE for NaCl 100 mg/L solution under the conditions of adsorption voltage/time, 1.5 V/3 min, desorption voltage/time -0.1 V/3 min, was shown 98%. And for the $CaCl_2$ and $MgSO_4$ solutions, the SREs of 70 and 59% were measured under the conditions of adsorption voltage/time, 1.2 V/3 min, desorption voltage/time -0.5 V/5 min, respectively.