• Membrane Journal
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• v.12 no.2
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• pp.75-89
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• 2002

The effect of addition of inorganic salts in polyethersulfone (PES) polymer solution on the membrane formation and ultrafiltartion performance was studied through the thermodynamic and kinetic properties of casting solution. To control the thermodynamic and kinetic properties of casting solution, various inorganic salts $[CaC1_2, LiCl, LiClO_4, ZnC1_2 $and Mg(ClO_4)_2]$ were added in the PES/NMP solution. Variation of membrane morphology and performance of the resulting membranes with change of the salt type and content added in tasting solution were discussed using viscosity, coagulation value, light transmittance measurement, overall membrane porosity, ultrafiltration experiment and cross-sectional SEM image. For all kind of inorganic salts, according as increase of the salt content in casting solution, viscosity is increased, coagulation value becomes lower, top layer thickness below the skin surface is increased, bovine serum albumin(BSA) rejection decreased and pure water flux is increased except $CaC1_2$ and LiCl. In case of $CaC1_2$ and LiCl, it is found that when the salt content is increased, the formation of macrovoids is suppressed and the precipitation rate becomes slow while instantaneous demixing of precipitation type is maintained. However, in case of $LiClO_4$ and $Mg(ClO_4)_2,$ it is found that precipitation rate becomes faster.

• Journal of Plant Biology
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• v.35 no.1
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• pp.1-8
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• 1992

The characteristic of Cyanophyte genus SG63 is similar to that of Aphanot hece sp. The optimal growth was found with the concentration of NaCI and $MgSO_4{\cdot}7H_2O$ on the culture medium. The most optimal condition is 56%0 of NaCl (S4 medium) and 20%0 of $MgSO_4{\cdot}7H_2O$ (M2 medium). The synthesis of chlorophyll a, phycocyanin and soluble proteins is affected by the concentration of the two mineral elements in culture. Especially, the content of chlorophyll a and phycocyanin decreases on the most highly saline medium. The identified principal carotenoids are ${\beta}-carotene$, echinenone, zeaxanthin and myxoxanthophyll. The rates of concentration of protein/chlorophyll a and phycocyanin/chlorophyll a are low on the S4 medium. Inversely, these rates are the highest on the M2 medium. Accordingly, the high concentration of $MgSO_4{\cdot}7H_2O$ provoke the synthesis of phycocyanin and total proteins.oteins.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.2
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• pp.1-11
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• 1989

Sandy dust phenomena was observed from April 19 to 23, 1988 in Seoul. During this period it rained and the precipitation was collected to investigate the rain chemistry. This study was carried out to analyzed the chemical composition of precipitation by the measurements of conditivity, cations $(H^+, NH_4^+, K^+, Na^+, Ca^{2+}, MG^{2+})$, and anions $(SO_4^{2-}, NO_3^-, Cl^-, F^-, Br^-)$ which are believed to be the major ions playing an important role in the acidity of rain water. During the period of sandy dust phenomena the range of pH value and conductivity concentration of rainwater were 6.0-6.7, 172-254 $\mu \mho/cm$. The anions and cations concentrations increased and the orders of these concentrations were $SO_4^{2-} > Cl^- > NO_3^- > Na^+ > Ca^{2+} > NH_4^+ > Mg^{2+}$. THe principal chemical compounds of rainwater were estimated at $(NH_4)_2 SO_4, CaSO_4, NaCl, and MgCl_2$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.86-92
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• 1998

부산 지하수의 오염실태와 그 특성을 파악하기 위하여 1996년과 1997년에 분석된 지하수 수질자료 중에서 pH, TS, KMnO$_4$소비량, Cl, SO$_4$등을 통계분석 하였다. 각 성분의 평균치는 pH가 모두 7.3, TS는 216.0 mg/$\ell$와 242.3 mg/$\ell$, KMnO$_4$소비량은 2.6 mg/$\ell$와 6.3 mg/$\ell$, Cl은 35.7과 50.1mg/$\ell$, SO$_4$는 25.4와 33.9mg/$\ell$이다. 2년 동안 pH의 음용수 기준치 초과 비율은 0.55와 0.47%, TS는 1.89와 2.50%, KMnO$_4$소비량은 0.73과 1.17%, Cl은 1.41과 2.18%, 그리고 SO$_4$는 0.37과 0.86% 이다. 따라서 성분별로 비교해 볼 때, pH의 음용수 기준치 초과비율이 가장 적고, Cl의 초과비율이 가장 크다. Cl 및 SO$_4$이온의 음용수 기준치(각각 100 mg/$\ell$, 200mg/$\ell$) 초과지점과 이 이온들의 평균치보다는 훨씬 큰 100 mg/$\ell$이상되는 지점들의 분포를 분석한 결과, 해안가보다는 내륙에 더 많이 초과지점들이 분포한다. 따라서 부산지하수는 해수에 의한 영향보다는 내륙에서 생활하수나 기타원인(공장폐수, 오염된 하천수, 폐기물 매립 등)에 의한 오염이 훨씬 큰 것으로 보인다. 1996년에 5개 성분의 음용수 기준치 초과비율은 5.06%이고, 1997년의 초과비율은 6.87%로 전년도에 비하여 약간 증가하였다. 그러나 부산이 바다에 접하고 또한 인구과밀 지역임을 고려할 때, 부산의 지하수 수질은 양호한 편이다. 따라서 앞으로 부산 지하수의 보전 및 관리가 적절하게 진행된다면 부산에서 지하수는 시민의 생활용수로서의 역할을 증대해 나갈 수 있을 것이다.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.104-110
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• 2001

In this study, the effect of physico-chemical variables on sludge conditioning was determined to enhance dewaterability of effluent produced from the thermophilic anaerobic digestion of food waste. The gas production rate and methane content during the anaerobic digestion of food waste were $1.1m^3/kg$ VS and 63%, respectively, and the biodegradability of volatile solids was 87.5%. The concentrations of CODcr, TKN and TP of effluent from digestor were 18,500mg/L, 2,800mg/L, and 582mg/L, respectively. At the jar test to screen the flocculant for the dewatering of effluent from digestor, $FeCl_3$ and strong cationic polymer were effective on making flocs in the effluent. The condition of flocculation of effluent were 500mg/L of $FeCl_3$ and 50-100 mg/L of strong cationic polymer, respectively. As the result of measuring of dewaterability potential of effluent to determine the mixing ratio between $FeCl_3$ and polymer by capillary suction time(SCT), optimum condition was 500mg/L of $FeCl_3$ and 80mg/L of strong cationic polymer.

• Journal of Pharmaceutical Investigation
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• v.5 no.3
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• pp.30-35
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• 1975

When the pH of the mixture containing oxytetracycline, $MgCl_26H_2O$ (2 : 1) and citric acid in aqueous solution is changed by adding monoethanolamine, some difference substances are produced. In the range of pH 8.5-9.3, the stable substance which exhibit U. V. max. absorption at 267.5-268 nm and 372.5 nm is produced. According to preparing method, the mixture of oxytetracycline. $MgCl_26H_2O$ (2 : 1) and citric acid in 75% propylene glycol aqueous solution are dissolved with monoethanolamine, and then, it is standed for a long time. An unknown substance is precipitated. It seems to be a compound containing $MgCl_26H_2O$, citric acid and monoethanolamine, but not oxytetracycline.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.760-766
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• 1998

This study was carried out far isolation and characterization of ammonia oxidizing bacteria (AOB) from aquacultural place and sludges of waste water collected in Pusan. One autotrophic AOB, Nitrosomonas sp. and 8 heterotrophic AOB (2 strains of Bacillus sp., 2 strains of Acinetobacter sp., Xanthomonas sp., Alcaligenes sp., Pseudomonas sp., Sphingobacterium sp.) were isolated. and identified. Variation of total nmmonia nitrogen (TAN) and $NO_2-N$ in mineral salt media containing 10mg/ $\ell$ of NHCl for 15 days in differents 9 strains was measured in order to examine the ablitity of ammonia oxidation. TAN was started to reduce after 4 days incubation and ca. 2 mg/$\ell$ of TAN was decreased after 15 days incubation by Nitrosomonas sp., At that time, $NO_2-N$ was produced to 0.023$\~$0.036 mg/$\ell$. Heterotrophic AOB showed the low ability of ammonia oxidation, 0.02$\~$0,04 mg/$\ell$ of TAN was decreased and $NO_2-N$ was produced to 0.01$\~$0.51 mg/$\ell$ after 15 days. When each strain of 8 heterotrophs was incubated in mimeral salt media containing 10 mg/$\ell$ $NH_4Cl$ and 50 mg/$\ell$ glucose, and 50 mg/$\ell$ $NH_4Cl$ and 5 g/$\ell$ glucose, the diminution of TAN was 1.12$\~$3.38 mg/$\ell$ and 1$\~$20 mg/$\ell$, respectively.

• Corrosion Science and Technology
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• v.22 no.5
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• pp.387-392
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• 2023

The objective of this study was to evaluate corrosion resistance of Zn-Al-Mg alloy coated steel in residential water with trace quantities of Cl^-. Comparative evaluations were performed using two commercial coated steel products, GI and Galvalume, as reference samples. Examination of corrosion morphology and measurement of weight loss revealed that the Zn-Al-Mg alloy coated steel exhibited higher corrosion resistance than reference samples. This finding suggests that the alloy coated steel possesses long-term corrosion resistance not only in highly Cl^- concentrated environments such as seawater, but also in environments with extremely low levels of Cl^- found in residential water. The primary factor contributing to the superior corrosion resistance of the Zn-Al-Mg alloy coated steel in residential water is the formation of an inhibiting corrosion product composed primarily of two phases: Zn₅(OH)₆(CO₃)₂ and Zn₅(OH)₈Cl₂·H₂O. The preferential dissolution of Mg from the corroded coating layer can increase alkalinity, which might enhance the thermodynamical stability of Zn₅(OH)₆(CO₃)₂.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.489-492
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• 2000

The rejection of hardness in a lactate fermentation broth was investigated by NTR-729 nanofiltration membrane. Firstly, a method for determining membrane surface charge was proposed on the basis of the rejection data for NaCl, $Na_2SO_4$, $MgCl_2$, $MgSO_4$ solutions. It was found that the NTR-729 membrane was negatively charged. The rejection of $Mg^{2+}$ ions in model solution of lactate was over 80% with lactate concentrations. But the rejection of $Mg^{2+}$ ions in fermentation broth of lactate was about 40 %. This results was caused by anions paired with $Mg^{2+}$ ions. It was found that the repulsive force of monovalent anions with membrane was almost few through an experiment of a mixed solution of NaCl/ $Na_2SO_4$. So the rejection of $Mg^{2+}$ ion in a fermentation broth was lower than that in a model solution because $Mg^{2+}$ ions permeated to the membrane with various monovalent anions.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.34-39
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• 2009

This study was carried out in order to investigate the decolorization and reduced sludge of real textile wastewater by coagulation process. The aim of the study was to verify the relation between decolorization and coagulants of real textile wastewater treatment processes. Coagulation processes were performed using $FeCl_3$, $FeSO_4$, and $Al_2(SO_4)_3$. Real textile wastewater has a mean concentration for BOD, COD, pH, color to be 800 mg/L, 600 mg/L, 9.7, and 102, respectively. From the experimental results, it was shown that the $FeCl_3$ exhibited higher decolorization at the operating conditions 335~2000 mg/L of coagulants and 500 mg/L NaOH dosage. The efficiency of color removal depended on the wastewater pH and concentration of coagulants.