• 한국환경보건학회지
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• 제22권4호
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• pp.62-68
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• 1996

Precipitation samples were collected by the wet-only event sampling method at Seoul from September 1991 to April 1995. Concentrations of samples for the ion components($NO_3^-, NO_2^-, SO_4^{2-}, Cl^-, F^-, Na^+, K^+, Ca^{2+}, Mg^{2+}$ and $NH_4^+$) were measured in addition to pH and electric conductivity. During the sampling period, 182 samples were collected, but only 163 samples were identified as valid. The pH, calculated from the volume-weighted $H^+$ concentration, was found to be 4.7, indicating a relatively intensive acidity compared with data from other regions of the world, where acid deposition was known to be a problem. Above all, the concentration of non-seasalt sulfate was $84 \mu eq/L$, which was the highest compared to that measured in other regions of the world. The major acidifying ions in the precipitation at Seoul were identified as sulfate and nitrate except for chloride, because the Cl/Na ratio in the precipitation was close to the ratio in seawater. If all of the non-seasalt sulfate and nitrate existed in the form of sulfuric and nitric acids, respectively, the average pH in the precipitation was calculated as 3.7, lower than the measured value. Consequently, the difference between the calculated and measured pH suggest that the acidity of precipitation was neutralized by alkaline species, not due to the low contribution of an anthropogenic air pollutants to the precipitation. The equivalent concentration ratio of sulfate to nitrate was 3.5, which indicated that the contributions of sulfuric and nitric acids to the precipitation acidity were 78% and 22%, respectively.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.132-139
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• 2018

A cost-effective preparation method is proposed to prepare nanoporous alumina (NA) using aluminum chloride as a precursor with a lower cost than aluminum butoxide. In addition, the surfactant template was replaced with magnesium stearate, which has a lower unit cost in stearate acid. The adsorption isotherm test for the CO gas was carried out to compare the adsorption performance of the NA adsorbents prepared using post-hydrolysis (NA) and cost-effective precipitation (C-NA). In addition, C-NA exhibited a similar uptake capacity as NA, and the maximum uptake capacity of Pd/C-NA increased 1.3 times via Pd nanodots loading.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.391-407
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• 2023

This article provides a survey of wet (aqueous) methods for recovery, separation, and purification of uranium from fission products in carbonate solutions during the reprocessing of spent nuclear fuel and methods for removal of radionuclides from alkaline radioactive waste. The main methods such as selective direct precipitation, ion exchange, and solvent extraction are considered. These methods were compared and evaluated for reprocessing of spent nuclear fuel in carbonate media according to novel alternative non-acidic methods and for treatment processes of alkaline radioactive waste.

• 한국대기환경학회지
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• 제22권4호
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• pp.487-498
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• 2006

Total 438 precipitation samples were collected in Jeju City between 1997 and 2005, and their major ionic components were analyzed. The comparison tests using ion balance, electric conductivity and acid fraction were performed. It was found their correlation coefficients were in the range of 0.977$\sim$0.994, indicating the good quality of collected dam. The volume-weighted mean pH and electric conductivity were 4.8 and 23.0 $\mu$S/cm, respectively. with the ionic strength of 0.23$\pm$0.20 mM. The marine ($Na^+$, $Mg^{2+}$, and $CI^-$), anthropogenic (nss$SO_4{2-}$, $NO_3^-$, and $NH_4^+$) and soil (nss-$Ca^{2+}$) species have contributed to the ionic components of precipitation samples with 43$\sim$74%, 16$\sim$37% and $\sim$5%, respectively. The seasonal variations of $NO_3^-$ and nss-$SO_4^{2-}$ showed a distinct seasonality with higher concentrations in winter than summer, indicating an increase of fossil fuel consumption and a possibility of long-range transport of those pollutants from continental area along the dominant winter westerly. The levels of nss-$Ca^{2+}$ also were appeared the highest in winter and increased comparatively in spring season. possibly due to the soil influences including the Asian Dust. The acidification contribution of nss-$SO_4^{2-}$ and $NO_3^-$ showed 88$\sim$96%, and the free acidity was in the range of 6.0$\sim$40.1%. Interestingly, the backward trajectories for the case of upper 10% nss-$SO_4^{2-}$ and $NO_3^-$ levels have passed through the China continent before their arrival to Jeju. The precipitation of pH below 4.5 has been occurred frequently when the trajectory's path lied over the China continents. On the other hand, the air masses from the North Pacific area were characterized by lower 10% of nss-$SO_4^{2-}$- and $NO_3^-$ concentration, which demonstrated that air mass from the North Pacific was the cleanest among air masses moved to Jeju.

• Applied Biological Chemistry
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• 제34권4호
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• pp.339-343
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• 1991

저장온도(실온, $35^{\circ}C$, $50^{\circ}C$)와 저장기간($1{\sim}10$개월)별로 보관한 인삼드링크제품의 $CO_2$ 압력, pH, 침전물 생성, 당도, 유리당, 색도, 조사포닌 및 ginsenoside 함량변화를 조사한 결과 $CO_2$ 압력은 실온에서 9개월후, $35^{\circ}C$에서 6개월후 및 $50^{\circ}C$에서 3개월후부터 각각 감소되었다. pH와 당도는 저장온도와 저장기간에 관계없이 각각 $3.17{\sim}3.21$과 $14.3{\sim}14.6$을 나타내었다. 색도, glucose와 fructose 및 panaxatriol계 사포닌은 저장온도가 높고 저장기간이 길수록 증가하였으나 sucrose와 panaxadiol계 사포닌은 감소하였다.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2156-2162
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• 2012

Many literatures focus on the biological relevance and the identification of biomarkers for disease activity assessment while less attention has been paid to the development of standard procedures for sample preparation and storage based on liquid chromatography technique. The influencing factors including protein precipitation, storage temperature, storage time, and reconstitution by ultra pure water were analyzed employing HPLC-DAD. The effects were investigated from five participants over three months by principal components analysis (PCA) and the values of percent changes (PC). The samples with protein precipitation might slow the rate of bacterial enzymatic conversion. After protein precipitation, the average PC of urine samples ($0.136{\pm}0.013$, n = 5) is relatively less than that of the serum samples ($0.173{\pm}0.026$, n = 5) for three months. Minimal effects on metabolic profiles of serum and urine (PC < 0.15) are reasonable for metabolomic studies after protein precipitation and storage at $-20^{\circ}C$ for two months.

• 대한화학회지
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• 제14권1호
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• pp.137-140
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• 1970

• 한국결정성장학회지
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• 제7권1호
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• pp.163-166
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• 1997

• 분석과학
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• 제29권1호
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• pp.19-28
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• 2016

2009~2014년에 제주지역의 강수시료(n=284)를 채취하여 주요 이온 성분을 분석하였다. 분석 정확도 확인을 위해 이온수지, 전기전도도, 산분율 비교법으로 회귀분석을 실시한 결과, 이들의 상관계수는 0.927~0.983의 범위로 양호한 직선성을 나타내었다. 강수의 부피가중평균 pH 4.9, 전기전도도는 22.7 µS/cm, 이온세기는 0.27±0.38 mM로 시료 중 약 35.9 %가 순수한 빗물 수준을 보였다. 강수 이온성분의 부피가중 평균농도(µeq/L)는 Na⁺ > Cl⁻ > nss-SO₄²⁻ > NO₃⁻ > NH₄⁺ > Mg²⁺ > H⁺ > nss-Ca²⁺ > PO₄³⁻ > K⁺ > HCOO⁻ > CH₃COO⁻ > NO₂⁻ > F⁻ > HCO₃⁻ > CH₃SO₃⁻ 순이었다. 강수의 산성화 기여율은 황산과 질산의 기여율이 각각 54.5 %, 36.5 %인 반면에 유기산 음이온인 HCOO⁻ 와 CH₃COO⁻ 의 기여율은 각각 4.8 %, 4.2 %를 나타내어 제주지역 강수의 산성화는 유기산보다는 주로 무기산에 의해 일어나고 있음을 확인할 수 있었다. 또한 중화인자를 확인한 결과, NH₃에 의한 중화인자는 33 %를 나타내었고 CaCO₃에 의한 중화인자는 20 % 이었다.

• 분석과학
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• 제33권1호
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• pp.33-41
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• 2020

Wet precipitation samples were collected in Jeju City and Mt. Halla-1100 site (a site at an altitude of 1100 m on Mt. Halla) during 2011-2013, and their major ionic species were analyzed to examine the chemical composition and characteristics. A comparison of ion balance, electric conductivity, and acid fraction of precipitation revealed correlation coefficients in the range of r = 0.950~0.991, thereby implying the high quality of analytical data. Volume-weighted mean pH and electric conductivity corresponded to 4.86 and 25.5 µS/cm for Jeju City, and 4.98 and 15.1 µS/cm for Mt. Halla-1100 site, respectively. Ionic strengths of the wet precipitation in Jeju City and Mt. Halla-1100 site corresponded 0.3 ± 0.5 and 0.2 ± 0.2 mM, respectively, thereby indicating that more than 30 % of total precipitation was within a pure precipitation criteria. The precipitation with a pH range of 4.5 - 5.0 corresponded to 40.8 % in Jeju City, while the precipitation with a pH range of 5.0 - 5.5 corresponded to 56.9 % in Mt. Halla-1100 site, thereby indicating slightly more weak acidity than that in Jeju city. The volume-weighted mean concentration (µeq/L) of ionic species was in the order of Na⁺ > Cl^- > nss-SO₄^2- > NO₃^- > Mg²⁺ > NH₄⁺ > H⁺ > nss-Ca²⁺ > PO₄^3- > K⁺ > CH₃COO^- > HCOO^- > NO₂^- > F^- > HCO₃^- > CH₃SO₃^- at Jeju City area, while it corresponded to Na⁺ > Cl^- > nss-SO₄^2- > NO₃^- > NH₄⁺ > H⁺ > Mg²⁺ > nss-Ca²⁺ > PO₄^3- > CH₃COO^- > K⁺ > HCOO^- > NO₂^- > F^- > HCO₃^- > CH₃SO₃^- at Mt. Halla-1100 site. The compositions of sea salts (Na⁺, Cl^-, Mg²⁺) and secondary pollutants (NH₄⁺, nss-SO₄^2-, NO₃^-) corresponded to 66.1 % and 21.8 %, respectively, in Jeju City and, 49.9 % and 31.5 %, respectively, in Mt. Halla-1100 site. The acidity contributions in Jeju City and Mt. Halla-1100 site by inorganic acids, i.e., sulfuric acid and nitric acid, corresponded to 93.9 % and 91.4 %, respectively, and the acidity contributions by organic acids corresponded to 6.1 % and 8.6 %, respectively. The neutralization factors in Jeju City and Mt. Halla1100 site by ammonia corresponded to 29.8 % and 30.1 %, respectively, whereas the neutralization factors by calcium carbonate corresponded to 20.5 % and 25.2 %, respectively. From the clustered back trajectory analysis, the concentrations of most ionic components were higher when the airflow pathways were moved from the continent to Jeju area.