• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.895-908
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• 2023

Disposal of waste containing heavy metals into the environment is a major threat to human health and can result in toxic or chronic poisoning in aquatic life. In the current study, metal-resistant Raoultella ornithinolytica was isolated from metal-contaminated samples collected from the Tanjaro River, located southwest of Sulaymaniyah, Iraq. R. ornithinolytica was identified by partial amplification of 16S rRNA. The uptake potency of heavy metals was assessed using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and indicated that R. ornithinolytica removed 67, 89, 63.4, 55.6, 56.5, 65, and 61.9% of Cd, Pb, Cr, Ni, Zn, Co, and Fe, respectively. These removal rates were influenced by temperature, pH, and contact time; at 35℃ and pH 5 with a change in the incubation time, the reduction rate improved from 89 to 95% for Pb, from 36.4 to 45% for Cu, and from 55.6 to 64% for Ni. Gene analysis indicated that R. ornithinolytica contained pbrT, chrB, nccA, iroN, and czcA genes, but the pcoD gene was absent. Energy-dispersive X-ray spectroscopy (EDS) images showed evidence of metal ion binding on the cell wall surface with different rates of binding. Transmission electron microscopy (TEM) detected different mechanisms for metal particle localization; cell surface adsorption was the main mechanism for Pb, Zn, and Co uptake, while Cd, Ni, and Fe were accumulated inside the cell. The current study describes, for the first time, the isolation of R. ornithinolytica from metal-contaminated water, which can be used as an eco-friendly biological expedient for the remediation and detoxification of metals from contaminated environments.

• Journal of the Mineralogical Society of Korea
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• v.16 no.3
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• pp.201-213
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• 2003

The adsorption property and ability of domestic zeolites for some heavy metal ions (Ag, Pb, Cr, Cu, Zn, Mn), which may cause a serious environmental problem in industrial wastewater, were evaluated on ore unit through a series of adsorption experiments together with careful examinations of mineral composition and properties of the zeolites. Though the adsorption behavior basically took place in the form of a cation exchange reaction, the higher CEC value does not necessarily to imply the higher adsorption capacity for a specific heavy metal. A general trend of the adsorption selectivity for heavy metals in the zeolites is determined to be as follow: $Ag\geq$Pb>Cr,Cu$\geq$Zn>Mn, but the adsorption properties of heavy metal ions somewhat depend on the species and composition of zeolite. Clinoptilolite tends to adsorb selectively Cu in case of Cr and Cu, whereas heulandite prefers Cr to Cu. A dominant adsorption selectivity of the zeolite ores for Ag and Pb is generally conspicuous regardless of their zeolite species and composition. The zeolite ores exhibit a preferential adsorption especially for $Ag^{+}$ so as not to regenerate when treated with $Na^{+}$ . In the adsorption capacity for heavy meta ions, the zeolites differ in great depending on their species: ferrierite>clinoptilolite>heulandite. Considering the CEC value of mordenite, the mordenite-rich ore appears to be similar to the clinoptilolite ore in the adsorption capacity. The adsorption capacity for heavy metals is not positively proportional to the CEC values of the zeolites measured by the exchange reaction with ammonium ion. In addition, the adsorption capacity roughly tends to depend on the zeolite contents, i.e., the grade of zeolite ore, but the trend is not consistent at all in some ores. These may be caused by the adsorption selectivity for some specific heavy metals, the presence of possible stacking micro-faults and natural cations such as K hardly to exchange in the zeolite. Considering the economic availability and functional effectiveness as natural zeolite resources, clinoptilolite ores could be applicable to utilize the domestic zeolites for the removal of heavy metals.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.6-12
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• 1998

To extract insoluble proteins and to improve functional properties of abolished proteins, a protease producing Aspergillus sp. MS-18 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. It was found that production of protease reached to the maximum when the wheat brae medium containing, 3% arabinose, 0.5% polypepton, 0.1% $(NH_4)_2SO_4$ and 0.2% magnesium chloride was cultured for 3 days. Protease was purified 16.9 folds after ion exchange chromatography and gel filtration and the specific activity was 340.4 unit/mg. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. The molecular weight of protease was estimated to be 30,000. Crystalization form of purified protease was a stick shape with rounding edges. The optimum pH and temperature for the protease activity were 9.0 and $60^{\circ}C$, respectively. The enzyme was stable in pH 7.0-12.0 at $50^{\circ}C$. The activity of purified enzyme was inhibited by $Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$ and $Pb^{2+}$, whereas it was activited by $Na^+$, $Mg^{2+}$ and $Mn^{2+}$. The activity of the protease was inhibited by the treatment with ethylenediaminetetraacetic acid and phenylmethane sulfonyl fluoride. The result suggests that the purified enzyme is a serine protease with metal ion at active site. Km and Vmax of purified protease were $29.33\;{\mu}mole/L$ and $5.13\;{\mu}g/min$, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.3
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• pp.15-22
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• 2023

BNKT Ceramics, one of the representative Pb free based piezoelectric ceramics, constitutes a perovskite(ABO3) structure. At this time, the perovskite structure (ABO3) is in the form where the corners of the octahedrons are connected, and in the unit cell, two ions, A and B, are cations, A ion is located at the body center, B ion is located at each corner, and an anion O is located at the center of each side. Since Bi, Na, and K sources constituting the A site are highly volatile at a sintering temperature of 1100℃ or higher, it is difficult to maintain uniformity of the composition. In order to solve this problem, there should be suppression of volatilization of the A site material or additional compensation of the volatilized. In this study, the basic composition of BNKT Ceramics was set to Bi_0.5(Na_0.78K_0.22)_0.5TiO₃ (= BNKT), and volatile site (Bi, Na, and K sources) were coated in the form of a shell to compensate additionally for the A site ions. In addition, the physical and electrical properties of BNKT and its coated with shell additives(= @BNK) were compared and analyzed, respectively. As a result of analyzing the crystal structure through XRD, both BNKT(Core) and @BNK(Shell) had perovskite phases, and the crystallinity was almost similar. Although the Curie temperature of the two sintered bodies was almost the same (TC = 290 ~ 300 ℃), it was confirmed that the d33 (piezoelectric coefficient) and Pr (residual polarization) values were different. The experimental results indicated that the additional compensation for a shell additive causes the coarsening, resulting in a decrease in sintering density and Pr(remanent polarization). However, coating shell additives to compensate for A site ion is an effective way to suppress volatilization. Based on these experimental results, it would be the biggest advantage to develop an eco-friendly material (Lead-free) that replaced lead (Pb), which is harmful to the human body. This lead-free piezoelectric material can be applied to a biomedical device or products(ex. earphones (hearing aids), heart rate monitors, ultrasonic vibrators, etc.) and skin beauty improvement products (mask packs for whitening and wrinkle improvement).

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.191-206
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• 2011

The emplacement ages, whole-rock geochemistry and Sr-Nd isotopic compositions of granitoid rocks from Cheongju area, South Korea, were investigated for delineating their petrogenetic link to the Jurassic Daebo granitoid rocks. Zircon crystals were collected from the diorite, biotite granite and acidic dyke samples in a single outcrop. Cross-cutting relationships show that the emplacement of diorite was postdated by the intrusion of biotite granite. Both rocks have been subsequently intruded by acidic dyke. The U-Pb isotopic compositions of zircon from the diorite, biotite granite, and acidic dyke were measured using a SHRIMP-II ion microprobe, yielding the crystallization ages of $174{\pm}2Ma$, $170{\pm}2Ma$, and $170{\pm}5Ma$, respectively, with 95% confidence limits ($t{\sigma}$). The emplacement ages are consistent with those determined from the above relative ages. The major and trace element patterns of the rocks are consistent with those of the Jurassic Daebo granitoid rocks, possibly suggesting a subduction-related I-type granite. The geochemical signature is, however, betrayed by the Sr and Nd isotopic compositions of these rocks. The isotopic signatures suggest that the rocks were produced either by the partial melting of lower-crust or by the mantle-derived magma contaminated by the basement rocks during its ascent and/or emplacement. In addition, the inherited ages of zircons of the rocks (ca. 2.1, 1.8, 0.8 and 0.4 Ga) suggest a possible assimilation with crustal rocks from the Gyeonggi massif and Ogcheon metamorphic belt.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.385-390
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• 1996

The electrical resistivity of the ceramic glaze coated on ceramic substrate plays an important role on the characteristics of the thick and thin film electrical circuits. In this study the effects of the various modifiers on the electrical resistivity were examined in SiO2-Al2O3-B2O3-RO-Na2O (RO=CaO , SrO, BaO, PbO) glass system. In alkali free glasses where divalent cations are responsible for electrical conduction the electrical conductivity of th glasses increased with the ionic size of divalent cations due to the decrease in the bond strength between oxyben and divalent cation. In Na2O containing glasses however where Na+ ion is responsible for electrical conduction the ionic conductivity decreased with the ionic size of divalent cations because the blocking effect of the cations on Na+ ion movement increased with larger divalent cations. Na+ ionic conduction also depended on the glass structure relaxation due to the corrdination number changes of B2O3 and Al2O3 which varied with the NaO2 content in the glass.

• Journal of Environmental Science International
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• v.6 no.5
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• pp.461-472
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• 1997

This study was carried out to investigate the characteristics of chemical components and precipitation at Kimhae area from March, 1992 to June, 1994. The pH values, concentration of soluble ions($Cl^-$, $NO_2^-}$ $NO_3^-}$, $NO_4^{2-}$-, $PO_4^{3-}$. $F^-$, $Mg^{2+}$, $Ca^{2+}$, $Mn^{2+}$, $K^+) and non-soluble metals(Cr.Si. Zn, Pb, Cu, Fe, Mn, Mg, Ad. V. Cal were measured by pH meter, IC (ion Chromatography) and ICP(Inductively Coupled Plasma). The data were analyzed by the dally. hourly distribution characteristics of acidity and chemical components, as well as the correlation between them. The results are as follows. 1. The pH range of precipitation was from 3.45 to 6.80 in Kimhae area. and average value was pH 4.62 and main chemical components were $SO_4^{2-}$, $Cl^-$, $NO_3^-$. The highest pH value and concentration appeared in initial rain, which might result from urbanlzation and industrialization in this area and long term transportation from China. 2. The hourly correction distribution of main anions related to pH value In the rainwater showed $SO_4^{2-}$ > $NO_3^-$ > $Cl^-$. Hourly concentration of heavy metal and each ion was highly correlated with pH in the precipitation.

• Fashion & Textile Research Journal
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• v.8 no.4
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• pp.458-464
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• 2006

The adsorption ability of heavy metal ions from the aqueous solution by chitosan, which it is well known natural biopolymer, has been investigated. The fundamental study in this research is focusing on the physicochemical adsorption utilizing the chitosan as a organic chelating adsorbent, adsorb especially heavy metal ions from the waste liquid solution. The adsorption ability of the chitosan between metal ions, having different characteristics with Mw of 188,600, 297,200, and 504,200 g/mol and degree of deacetylation (DD) of 86.92% and 100% were investigated targeting on the $Ni^{2+}$, $Co^{2+}$, $Zn^{2+}$, and $Pb^{2+}$ ions, respectively. The uptake of heavy metal ions with chitosan was performed by atomic absorption flame emission spectrophotometer (AAS) as conducted residual metal ions. It was found that chitosan has an strong adsorption capacity for some metals under certain conditions. Chitosan, which have 100% degree of deacetylation showed high adsorption recovery ratio and have an affinity for all kinds of heavy metals. In contrast, the molecular weight of chitosan was not completely affected on metal ion adsorption.

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.45-53
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• 2006

In this study, we prepared porous cation exchange membrane using polystyrene such as, EPS (expanded polystyrene), SAN (styrene acrylonitrile copolymer) and HIPS (high impactive polystyrene). These polystyrenes were sulfonated by acetyl sulfate to make porous cation exchange membrane such as, SEPS, SSAN, SHIPS. SEM was employed to confirm porous structure of membrane, and IR spectroscopy was used to confirm sulfonation rate of ion exchange membrane. Water and methanol content were also increased with amount of sulfuric acid in reactants. SSAN-20 showed the highest value in water and methanol content. Fixed ion concentration and conductivity was also increased with an amount of sulfuric acid in reactants. Methanol permeability for SEPS-20, SSAN-20, SHIPS-20 was found to be $1.326\;{\times}\;10^{-5}\;cm^2/s$, $1.527\;{\times}\;10^{-5}\;cm^2/s$ and $1.096\;{\times}\;10^{-5}\;cm^2/s$ respectively. From the result of electrodialysis experiment in 0.03 M $Pb(NO_3)_2$ aqueous solution, anion exclusion and cation selection effects were confirmed.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.149-154
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• 1999

Response Surface Methodology was applied for optimizing the processing parameters of ultrasound treatment in order to produce low-molecular alginate. The use of ultrasound significantly reduced viscosity of alginate solutions. Suggested parameters of ultrasound treatment for maximum reduction of alginate molecular weight were: specific intensity, 115.81 $W/cm^2$ at 20kHz frequency; treatment time, 35.55 min; temperature, $20.08^{\circ}C$; alginate concentration, $2.5\%$. Low-molecular alginate obtained by ultrasound had two peaks on Sepharose CL-6B gel filtration. The viscosities of control, fraction I, and fraction II at $0.1\%$ concentration and $25^{\circ}C$ were 3.07, 1.23, and 0.82cps, respectively. Molecular weights of control, fraction I, and fraction II alginates were 336,500, 70,400, and 52,800 daltons, and their solubilities were 3, 6, and $14\%$, respectively. The lower molecular weight of alginate, the lower the alcohol precipitation and the higher $Ca^{2+}$ ion binding capacities. Heavy metal ion binding capacities of alginates were high in the following order of Pb, Cd, Zn, and Co.