• 공업화학
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• 제19권6호
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• pp.690-692
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• 2008

바이오디젤 부산물로부터 중화, 침전, 증류 등의 처리 공정을 거쳐 순수한 글리세롤을 분리할 수 있었다. 황산, 인산, 염산 등을 이용하여 산의 농도와 중화처리 온도에 따라 전처리, 증류공정을 통하여 얻어진 글리세롤 함량을 비교하였다. 염산은 5~37 wt%, 황산은 5~95 wt%, 인산은 5~85 wt% 범위 내에서 각각 중화 실험을 수행하였다. 중화처리 침전온도는 각 산에 대해 293~333 K 범위 내에서 변화시켰다. 그 결과 10 wt% 황산과 313 K의 85 wt% 인산처리 침전 온도로 각각 중화 처리한 경우에서 염 제거가 잘 이루어져 증류된 글리세롤 함량이 가장 높았다. 산 농도와 전처리 온도 조건의 변화는 바이오디젤 부산물로부터의 글리세롤 회수에 어느 정도 영향을 미쳤다.

• 한국대기환경학회지
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• 제1권1호
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• pp.33-41
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• 1985

In order to investigate the Phenomenon of Acid Precipitation, pH value and Anions of Fluroide, chloride, nitrite, phosphate, bromide, nitrate and sulfate were measured from the acid precipitations sampled around 7 districts over seoul area during period of 9 months from January till September, in 1985. From the distribution of pH value gatnered, acid precipitations were noticed during period from January till Aprill, and from as of April 22nd, situation gradually recovered. The average pH value till April showed comparatively low, ranging 4.0-5.0. The pH value of 4.5-5.6 in average over whole year reaches to similar level of those in Japan. Anion analysis revealed that the main factor of pH value in Seoul district attribute mainly to the sulfate ion and nitrate ion. Moreover, these Phenomena of acid precipitation in Seoul area appeared to concentrate on certain districts, and they are slowly moving toward other directions due to such factors as wind-velocity and directions.

• 방사성폐기물학회지
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• 제10권2호
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• pp.77-85
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• 2012

본 연구는 우라늄-함유 석회침전물로부터 U을 제거(/회수) 하기위하여 탄산염 산화용해-산성화 침전과 질산용해-과산화수소 침전을 각각 고찰하였다. 석회침전물 내 우라늄을 용해하는 관점에서는 질산용해가 유리하나 (약 98% 이상 용해) 이 경우 U과 Al, Ca, Fe, Mg, Si 등의 공존 불순물이 다량 공용해되고, 또한 과산화수소 침전에서도 상당량의 불순물이 U과 함께 공침전 된다. 한편 탄산염 용해에 의한 산성화 침전은 우라늄의 용해가 90% 이하로 방사성 고체페기물의 부피감용 측면에서는 질산용해 보다 덜 효율적이지만, 우라늄과 불순물의 공용해나 산성화 침전에 의한 우라늄과 불순물의 공침전이 거의 일어나지 않아 보다 순수한 U을 회수하는 측면에서는 매우 효과적이다.

• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3239-3243
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• 2014

We have developed a simple method for tuning the morphologies of $Cu_2O$ microcrystals. $Cu_2O$ microcrystals were prepared by precipitation at room temperature from a mixture of $Cu(CH_3COO)_2{\cdot}H_2O$, N,N,N',N'-tetramethyl ethylenediamine (TMEDA), ascorbic acid, and polyethylene glycol (PEG). TMEDA was used to promote the formation of copper-TMEDA complexes. A variety of $Cu_2O$ microcrystal morphologies were obtained simply by varying the concentrations of TMEDA and ascorbic acid. Aggregated $Cu_2O$ microspheres are formed at higher concentrations of ascorbic acid in the absence of TMEDA. Aggregated $Cu_2O$ microcubes are formed at lower concentrations of ascorbic acid and higher concentrations of TMEDA. The crystal growth mechanism of these $Cu_2O$ morphologies is explained.

• 한국대기환경학회지
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• 제10권3호
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• pp.159-169
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• 1994

This paper describes the process of acidic precipitation from the atmosphere to the ground water, The net deposition of wet precipitation to the ground surface is obtained by subtracting the interception loss due to plant leaves and evaporation from the amount of total precipitation. As the water immerses through the vegetation and the different soil layers the various chemical reactions take place. The relationship between the acidic precipitation by increasing industrial emissions and the soil acidification mechanism is discussed. The report focuses on the buffering action that involves the proton budget in soil and rocks. Based on the soil constituents, the six buffer ranges of the soil are classified and each buffering process is illustrated. In addition, the Possibility of the contamination of drinking-water reservoirs by continuous acid burden is emphasized.

• 한국대기환경학회지
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• 제11권1호
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• pp.57-68
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• 1995

Precipitation samples were collected by a wet-only automatic acid precipitation sampler at Kangwha island on the western coast in Korea, through January until December 1992. pH, electric conductivity and the concentrations of major water-soluble ion components such as N $H_{4}$$^{+}$, $Ca^{2+}$, $K^{+}$, $Mg^{2+}$, N $a^{+}$, N $O_{3}$$^{[-10]}$ , S $O_{4}$$^{2-}$ and C $l^{[-10]}$ were measured. From the result of checking the validity for assesment of pollution level of precipitation samples by pH using correlation analysis between pH and major components, and t-test of chemical composition between acid rain and non-acid rain, pH proved to be not satisfactory for its pillution level. A more comprehensive method is therefore required. In order to estimate the monthly analytical result of chemical composition of precipitation samples comprehensively, a cluster analysis was used among the various multivariate statistical analysis. As a result of making a cluster analysis for separating the monthly precipitation samples into homogeneous patterns by setting the concentrations of nine major water-soluble ion components as a variable, three homogeneous patterns were obtained. The first pattern was a group of months having average ion concentrations, the second a guoup of months having low ion concentration, and the third a group of months having high ion concentrations. Thus, it was indicated that the pollution level of precipitation was higher on February and lower on May, June, August and September than the other months. As a result, this analysis method could be estimated the chemical coposition of precipitation regionally as well as monthly.monthly.

• 자원리싸이클링
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• 제1권1호
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• pp.58-68
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• 1992

아연을 함유하고 있는 산업폐기물로부터 첨단산업의 소재원료인 미립의 고순도 ZnO 분말을 아연제련의 용매추출 공정에서 직접 합성할 수 있는 방법을 개발하고자 하였다. 아연 함량이 55%인 선재산업의 폐기물을 황산으로 침출하여 아연을 추출하였다. 함아연 용액에서 철분을 침전시켜 제거한 후 D2EHPA를 추출제로 사용하는 용매추출에 의해 아연이온을 유기상으로 추출하여 정제한 뒤 oxalic acid와 같은 침전제를 사용하여 유기상의 아연 이온을 precipitation stripping 법으로 탈거, 침전시켜 $ZnC_2O_4$ 분말을 합성하였으며 이를 해소하여 99.9% 이상의 ZnO 분말을 제조하였다. 황산농도, 침출시간, 황액농도가 아연의 침출율에 미치는 영향과 용매추출시 용액의 산도에 따른 아연과 불순물의 추출거동을 조사하여 최적정제조건을 얻었다. 또한 oxalic acid의 농도, 온도, 계면활성제의첨가, 침전시간 등이 생성된 $ZnC_2O_4$ 분말의 형상과 입자크기 및 분포에 미치는 영향에 대해 조사하였다.

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.369-373
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• 2002

The liquid phase oxidation of p-xylene has been carried out with oxygen-enriched gas, and the manganese component was precipitated probably via over-oxidation to $Mn^{4+}$. The precipitation increased with rising oxygen concentration in the reaction gas and occurred mainly in the later part of the oxidation. The activity of the reaction decreased, and the blackening of the product and side reactions to carbon dioxide increased with the degree of precipitation. Precipitation can be decreased with the addition of metal ions, such as cerium, chromium and iron.

• The Korean Journal of Ecology
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• 제13권2호
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• pp.131-142
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• 1990

From July 1, 1985 to June 30, pH values of precipitation in Seoul area were average 5.1 and acid rain which was lower than pH 5.5 showed a frequence of 70.7%. Seasonal changes appeared in pH values of annual precipitation in Seoul. The pH patterns of spring and autumn were generally less acid than that of summer and winter, and snowfall pH was lower than rainfall. The beginning rainfall in Seoul was neutral because of alkali dust in the atmosphere. As times went on, rainfall pH was gradually low and after 1 to 2 hours, showed a steady state. On the surface soil precipitation was neutralized by soil buffering capacity.

• 한국환경과학회지
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• 제1권1호
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• pp.29-39
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• 1992

A study on acidity in precipitation was carried out during May 1990 - April 1991 at two sites in Chongwon, Choongbook. We observed variations of pH from 4.0 to 7.0. Annual mean value of pH was 5.21 in the area. In particular, strong acidity of rain fall, pH 4.0 were observed during winter to early spring. Neutral values were observed during June to July and were due to wet deposition of atmospheric pollutants by stationary fronts in the rainy season. Interestingly, acidity of snow observed in winter was neutral and it was weaker than the acidity of rain in winter by a value of 2.0. Discussion is made on meteorological and chemical analyses and seasonal variations of acidity of precipitation.