• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.2
• /
• pp.609-617
• /
• 2013

The objective of this study was to evaluate the oxidation method to remove endocrine disrupting chemicals in reverse osmosis(RO) retentate for the reuse of wastewater effluent. Oxidation of organic pollutants was induced by the persulfate catalyzed by Fe(II). Affecting factors such as initial pH and ionic strength on the Fe(II) catalyzed persulfate oxidation were evaluated. $17{\alpha}$-ethynylestradiol (EE2) degradation efficiency decreased as pH and ionic strength increased. However, the efficiency increased as chloride ion concentration increased due to the influence of radical transfer.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.10
• /
• pp.1159-1164
• /
• 1999

The study investigated the effect of carrier composition (ionic strength and pH) on the retention of various proteins in flow field-flow fractionation (Flow FFF) as well as the conformational change of Bovine Serum Albumin (BSA) with urea concentration, storage time and temperature. The study found that the retention of protein in Flow FFF increased with the ionic strength of the carrier liquid. Most proteins were well solubilized at pH = 7-8. The hydrodynamic diameters obtained from Flow FFF retention data agree well with theoretical values. The retention increased and the peak shape became distorted at extreme pH conditions of the carrier solution. The selected carrier composition for comparison between the literature value of proteins was 0.05 M tris buffer solution with a pH of 8. Storing BSA at 4 ±2℃ over a period of three months resulted in slow dimerization. Also, in case of the storage of BSA at 37 ±5℃ for one week, the retention of both BSA monomer and dimer increased with the urea concentration. Finally, the structural composition of specific enzymes: malonyl-CoA decarboxylase (MCDC) and malonyl-CoA synthesis (MCS) was determined by using Flow FFF at specific carrier solutions. The molecular weight of the natural MCDC was determined to be 208 kDa, which means it is a homotetramer, while that of the MCS was determined to be 47 kDa, which means it is a monomer.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.1
• /
• pp.104-110
• /
• 2016

The transport of silver nanoparticles (AgNPs) was investigated through a column packed with sand. A series of column experiments were carried out to evaluate the effect of ionic strength (IS), pH, electrolyte type and clay mineral on mobility of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs). The deposition of PVP-AgNPs was increased with increasing solution ionic strength and decreasing pH. Furthermore, the depositon of PVP-AgNPs was affected by the electrolyte type (NaCl vs. NaNO₃) and was shown to be greater at NaNO₃ solution. Also, the transport of PVP-AgNPs was greatly increased after the pre-deposition of clay particles on sand. Our results suggest that various environmental factors can influence the mobility of PVP-AgNPs in soil-groundwater systems and should be carefully considered in assessing their environmental risks.

• Electrical & Electronic Materials
• /
• v.11 no.11
• /
• pp.9-17
• /
• 1998

The dependence of the ionic conductivity on the B-site ion substitution in (Li0.5La0.5)Ti1-xMxO3 (M=Sn, Zr, Mn, Ge) system has been studied. Same valence state and various electronic configuration and ionic radius of Sn4+, Zr4+, Mn4+ and Ge4+(4d10(0.69$\AA$), 4p6(0.72$\AA$), 3d10(0.54$\AA$) and 3d3(0.54$\AA$), respectively) induced the various crystallographic variaton with substitutions. So it was possibleto investigate the crystallographic factor which influence the ionic conduction by observing the dependence of the conductivity on the crystallographic factor which influence the ionic conduction by observing the dependence of the conductivity on the crystallographic variations. We found that the conductivity increased with decreasing the radii of B-site ions or vice versa and octahedron distortion disturb the ion conduction. The reason for this reciprocal proportion of conductivity on the radius of B-site ions has been examined on the base of the interatomic bond strength change due to the cation substitutions. The results were good in agreement with the experimental results. Therefore it could be concluded that the interatomic bond strength change due to the cation substitutions may be the one of major factors influencing the lithium ion conductivity in perovskite(Li0.5La0.5) TiO3system.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.4
• /
• pp.287-293
• /
• 2009

This study investigated the influence of ionic strength on the adhesion and release of bacteria (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus) in quartz and iron-coated sands using column experiments. Results show that the mass recovery remained constant (E. coli = 13.7${\pm}$0.5%, B. subtilis = 9.8${\pm}$1.3%, S. aureus = 13.0${\pm}$2.1%) in iron-coated sand while it decreased from 80.7 to 45.3% (S. aureus) in quartz sand with increasing ionic concentrations from 1 to 100 mM. As the ionic concentrations of leaching solution was lowered from 100 to 0.1 mM, average 39.1% of bacterial detachment was quantified from quartz sand, but no bacterial release was observed in iron-coated sand. The phenomenon observed in iron-coated sand can be attributed to the inner-sphere complexes between bacteria and coated sand, which have minimal effect from ionic strength. This study improves our knowledge regarding the bacterial interaction with surface-modified porous media.

• Korean Journal of Food Science and Technology
• /
• v.30 no.1
• /
• pp.69-76
• /
• 1998

This study was investigated to determine the effect of additives and ionic strength on the functionality of extracted proteins in preblends in order to use less additive in restructured meat products. Preblends contained the combinations of sodium chloride (NaCl; 0, 4.5, 9.0%), sodium tripolyphosphate (STPP; 0, 2.5, 5.0%), and tetrasodium pyrophosphate (PP; 0, 2.44, 4.88%). The pH values increased linearly with increasing STPP and PP concentrations (p<0.01). In the equivalent ionic strengths, PP was more effective than STPP in increasing pH. Phosphate ions were more effective on total extractable protein (used 1 M NaCl buffer) than chloride ion at equivalent ionic strengths. Solubility was decreased by adding NaCl and increasing total extractable proteins. Meat sulfhydryl contents were high with increasing total extractable proteins. When protein extracts were heated at $65^{\circ}C$, 7 min, meat sulfhydryl contents decreased and surface hydrophobicity increased (p<0.01). However, all protein extracts showed no differences in SDS-PAGE pattern. In conclusion, PP is more effective than STPP in order to use less additive but there was no linear relationship between functionnal improvement and ionic strength.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.6
• /
• pp.1519-1526
• /
• 2010

The behavior of peptide or protein solutes in saline aqueous solution is a fundamental topic in physical chemistry. Addition of ions can strongly alter the thermodynamic and physical properties of peptide molecules in solution. In order to study the effects of added ionic salts on protein conformation and dynamics, we have used the molecular dynamics (MD) simulations to investigate the behavior of Staphylococcus aureus Hfq protein under two different ionic concentrations: 0.1 M NaCl and 1.0 M NaCl in presence and absence of RNA (a hepta-oligoribonucleotide AU5G). Hfq, a global regulator of gene expression is highly conserved and abundant RNA-binding protein. It is already reported that in vivo the increase of ionic strength results in a drastic reduction of Hfq affinity for $Q{\beta}$ RNA and reduces the tendency of aggregation of Escherichia coli host factor hexamers. Our results revealed the crucial role of 0.1 M NaCl Hfq system on the bases with strong hydrogen bonding interactions and by stabilizing the aromatic stacking of Tyr42 residue of the adjacent subunits/monomers with the adenine and uridine nucleobases. An increase in RNA pore diameter and weakened compactness of the Hfq-RNA complex was clearly observed in 1.0 M NaCl Hfq system with bound RNA. Aggregation of monomers in Hfq and the interaction of Hfq with RNA are greatly affected due to the presence of high ionic strength. Higher the ionic concentration, weaker is the aggregation and interaction. Our results were compatible with the experimental data and this is the first theoretical report for the experimental study done in 1980 by Uhlenbeck group for the present system.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.2
• /
• pp.195-207
• /
• 2015

Physical properties of strontianite ($SrCO_3$) synthesized under variable conditions such as different ionic strength, temperature, and aging time were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). All synthesized samples show a single phase of strontianite. Crystallinity of the synthesized strontianite increases with increasing temperature and ionic strength with $NaNO_3$. Crystal sizes of the samples increase dramatically, and their morphology changes from rod or dendritic to prismatic shape as ionic strength and temperature of the solution increase. In addition, crystal sizes increase, and their morphology changes from rod or prismatic crystals to spheroidal aggregates with increasing aging time. These results suggest that changes in conditions of the synthesis for strontianite play an important role in controlling the crystallinity and morphology of results provide crucial information on the prediction for the physical properties of strontianite under different conditions during the formation of strontianite crystals.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.2
• /
• pp.119-124
• /
• 2009

The aim of this study was to investigate the influence of ionic strength and iron impregnation on the attachment of Enterococcus faecalis to granular activated carbon (GAC). Column experiments were performed to examine bacterial adhesion to coconutbased GAC (c-GAC), iron-impregnated c-GAC (fc-GAC), acid-washed c-GAC (a-GAC) and iron-impregnated a-GAC (fa-GAC) under two different solution (NaCl 1, 10 mM) conditions. Results showed that bacterial mass recovery in c-GAC decreased from 77.3 to 61.6% while in a-GAC it decreased from 71.6 to 32.3% with increasing ionic strength from 1 to 10 mM. This indicates that bacterial attachment to GAC can be enhanced with increasing ionic strength. Results also showed that the mass recoveries in fc-GAC were 62.6% (1 mM) and 53.3% (10 mM) while they were 50.8% (1 mM) and 16.9%(10 mM) in fa-GAC, which were lower than those in c-GAC and a-GAC. This demonstrates that bacterial adhesion to GAC can be enhanced through iron impregnation. This study provides information regarding the effects of ionic strength and iron impregnation on bacterial attachment to GAC. Furthermore, this study will advance our knowledge of bacterial removal in surface-modified granular media.

• Journal of Korean Society on Water Environment
• /
• v.25 no.2
• /
• pp.288-294
• /
• 2009

Flow field-flow fractionation (Fl-FFF) device has been widely used to verify the size and molecular weight of various colloids and organics. The Fl-FFF, however, generally uses carrier solutions with only low to moderate ionic strengths to exclude the high affinity of materials to the membrane under high ionic strength conditions. Thus, materials existing in seawaters have not been accurately analysed based on the hydrodynamic size and molecular weight using current Fl-FFF techniques. The highest ionic strength tested was up to 0.1 M, while seawater ionic strength is about 0.6 M. The aim of this study is to accurately measure the hydrodynamic size of particles under carrier solutions close to seawater conditions with the Fl-FFF. By employing various operating conditions during the Fl-FFF analyses, it was demonstrated that the flow conditions, the concentration of surfactants, and stabilization times were key factors in acquiring compatible data. Results have shown that the cross flow was more influential factor than the channel flow. The concentration of the surfactant was to be at least 0.05% and the minimum 15 hr of stabilization was needed for accurate and reproducible data acquisition under seawater condition.