• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.871-878
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• 2006

Batch experiments were performed to evaluate the applicability of soil washing for heavy metal contaminated soils at Nacdong and Hamchang abandoned mines. The texture of the Nacdong soil was sandy loam. Nacdong abandoned mine soil was almost neutral (pH=6.5). Contaminations of As, Cd, Pb and Zn for Nacdong mine soils were 12,900 mg/kg, 29 mg/kg, 696 mg/kg and 276 mg/kg, respectively. Hamchang abandoned mine soils were acidic (pH=2.6) and the soil texture was loam. The contaminations of As, Cd, Pb and Zn for Hamchang abandoned mine soils were 6,410 mg/kg, 291 mg/kg, 1,300 mg/kg and 1,110 mg/kg, respectively. For the Nacdong abandoned mine soils, oxalic acid was found to be the most effective soil washing extracter for As and Pb while citric acid was the most effective extracter for Cd. For the Hamchang abandoned mine soils, oxalic acid showed the highest extraction efficiencies for As and Pb, whilst citric acid presented the best soil washing efficiencie for Cd. Oxalic acid and EDTA were found to be the most effective soil washing extracter for the Hamchang abandoned mine contaminated soils.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.83-95
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• 2004

The removal efficiency of several washing agents on the $Cs^+$ ion was investigated. Leaching of $Cs^+$ ion from the soil surface by washing agents is affected by the exchange capability of the washing solution. Reuse tests of the effective soil washing agents such as $BaCl_2$, NaOH, citric acid＋ $HNO_3$ and oxalic acid were performed. NaOH, citric acid ＋ $HNO_3$ and oxalic acid solutions can be reused after passing through the ion exchange column. Among the tested solutions, both of citric acid＋ $HNO_3$ and oxalic acid were effective for the decontamination of TRIGA research reactor soil. The radioactivity of soils can be reduced to a release level by the successive application.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.87-101
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• 1999

This study has been carried out to examine the feasibility of washing technique for reducing the heavy metal contamination level of tailing wastes and agricultural soil surrounding abandoned metal mines. Some organic acids with low molecular weight were used as washing solution. Initial contamination levels of copper and lead for some soil samples were found to exceed the standard levels of countermeasure and concern, and those of cadmium to approach the standard level of countermeasure. Experimental results using sequential extraction method revealed that more than half of copper and lead existing in tailing wastes are adsorbed forms available for plants. There are some proportional relationships between metal concentrations determined by using 0.1N HCI solution and those determined by sequential extractions. Citric acid was turned out to be superior to oxalic acid and acetic acid with low molecular weight in washing above three metals. When citric acid is used for washing heavy metals from soil, it is desirable to operate at pH less than 5.5 for better washing effect. Metal removal effect by citric acid solution has been proved to depend upon solution concentration and the mass ratio of solution to soil. Addition of SDS(Sodium Dodecyl Sulfate) to citric acid improved the washing effect of cadmium among three metal most significantly. while copper removal did not change. Washing technique using citric acid for removal of heavy metals from agricultural soil or tailing wastes is recognized to be an effective remediation method.

• Proceedings of the Costume Culture Conference
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• 2003.12a
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• pp.21-26
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• 2003

I 의류의 염색 및 가공 1. 염색 방법 (섬유제품에 의한 분류) ① 섬유 염색 (Fiber Dyeing) ②사염 ③ 원단 염색 ④ 의류 염색 2. 염료 종류에 따른 염색 (Cellulose 섬유를 중심으로) ① 직접 염료에 의한 염색 ② 반응성 염료에 의한 염색 ③ VAT 염료에 의한 염색 ④ Pigment Dyeing ⑤ 형광 증백제에 의한 염색 3. Washing 가공 ① Normal Washing ② Stone Washing ③ Bio Washing ④ Acid Washing ⑤ Sand Washing (중략)

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.808-816
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• 2008

In the present paper, a study has been performed on remediating mine tailings around abandoned mine contaminated with high concentrations of arsenic and heavy metals using the technique of soil washing. Through the removal experiment of arsenic, the optimal conditions in the type and concentration of washing reagent, mixing ratio of mine tailings and washing reagent, and washing time were derived. Results showed that the most effective washing reagents to remove arsenic from mine tailings were oxalic acid(72% removal efficiency) and phosphoric acid(65%), while the oxalic acid(89%) was the most effective in removing the heavy metals containing Cu. In addition, the most economical and efficient washing concentration was 0.25 M and the most suitable washing time was 30 minutes. The optimal mixing ratio of mine tailings and washing reagent was 1 : 20(mass/vol) from the viewpoint of minimization of wastewater produced after the washing, as well as the washing effectiveness. Although the mixture of washing reagents did not help in removal of arsenic, it could lead to much elevated synergy effect on removing Cu and Zn, compared with the single reagent.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.299-304
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• 2001

For the remediation of the contaminated soil with heavy metals, Cd, Cr, Cu, and Pb, the reaction parameters were optimized. Tartaric acid (TA) and oxalic acid(OA) as a washing agent and recovery of metals, The optimum washing conditions of TA and OA were in the ratio of 1 : 20 between soil and acid solution during 2hr reaction under unbuffered pH solutions. At the optimized reaction conditions, the removal efficiencies were compared with that of 0.1 M HCl and ethylenediamine tetraacetic acid(EDTA). TA showed higher efficiency on the removal of Pb than that of EDTA, which established for the remediation of contaminated soil with Pb and Cd metals. The recovery of metal ions from washing solution was achieved by adding calcium hydroxide and sodium sulfide by forming the precipitation of metal hydroxide and metal slfied. Optimum amounts of sodium sulgide and calcium hydroxide were Cd = 25g/$\ell$, Cu = 5~10g/$\ell$ and Pb = 5~10g/$\ell$ for the washing solution of OA and 2~5g/$\ell$ for the washing solution of TA, respectively. The amounts of $Na_2S$ and $CA(OH)_2$ for the tartaric acid was less than that of oxalic acid.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.45-54
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• 2000

Several chemical washing procedures were applied to Zn and Cd contaminated soil. Batch and column tests were performed to determine the metal extraction efficiency as a function of pH and concentration. Washing efficiencies by water and NaOH are very low but those by HCI, EDTA and Oxalic acid are high. The most efficient washing occurs in case of using HCI because heavy metal is ionized easily at the condition of low pH. EDTA and Oxalic acid are also effective to extract Zn and Cd because they have a high complexation affinity for heavy metals forming active surface complexes. More Zn is released than Cd is and release trend is increased as pH is decreased and concentration of washing solution is increased. When heavy metal contaminated soil is remediated, HCI and EDTA are more effective to remove Zn than others are. Meanwhile HCI and Oxalic acid are more effective to remove Cd than others are.

• Journal of Soil and Groundwater Environment
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• v.15 no.5
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• pp.23-31
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• 2010

For an efficient remediation of Pb-contaminated soil (S-1) in a clay shooting range, a soil washing test was performed with mineral acid, organic acid, chelating agent, and chloride. The Pb extraction efficiency of extractant (0.1 M) used in the washing test showed the order of HCl > $Na_2$-EDTA > NTA > DTPA > citric acid > malic acid > succinic acid > acetic acid > $CaCl_2$ > $MgCl_2$, for S-1 soil. As compared to initial Pb concentration, extraction efficiency by the concentration of extractant was 93.35%, 80.80%, 73.92%, and 24.57% in S-1 soil for HCl (0.5 M, pH 1.10), $Na_2$-EDTA (0.01 M, pH 3.99), citric acid (0.5 M, pH 1.27), and $MgCl_2$ (0.1 M, pH 8.82), respectively. S-1 soil had 56.83% of residue form and 43.17% of non-residue form (18.04% of exchangeable form), respectively. Although the concentrations of these fractions sharply decreased after HCl washing, since the exchangeable forms with relatively large mobility are still distributed as high as 18.78% (to Pb total content in residual soils) in S-1 soil, it is necessary to devise a proper management plan for residual soils after soil washing application.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.499-506
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• 2007

This study aims to propose evaluation methods of chemical washing performance and estimate the washing capability by flowing detergent/water solution for application to home appliances such as dishwashers. Standard pollutant is stearic acid. A numerical study is also tried using a SIMPLER code. Preliminary experiments are performed by varying the concentration and temperature of the solution. From the pre-experiments, 10 minute pre-curing time is found to be necessary to remove the stearic acid. Stoichiometric ratio and detergent consumption coefficient of reaction between the detergent and stearic are estimated following a proposed method. Washing experiments of pollutant to compare with the numerical results are performed. The relative errors between the experimental and the numerical results with pre-curing time included are less than 7%. In conclusion, important mechanisms of chemical washing are revealed and methods of predicting washing performance are well established.

• Food Engineering Progress
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• v.23 no.2
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• pp.112-117
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• 2019

The purpose of this study is to develop a method to cultivate lactic acid bacteria (LAB) as a by-product in the fermentation of kimchi through the use of Chinese cabbage leaves. A method to reduce the initial number of microorganisms using citric acid and ethanol to wash cabbage leaves was investigated. In this experiment, Chinese cabbage leaves were washed using a mixture of 3% citric acid and 7% ethanol and the washed cabbage leaves were juiced and used as a sample. The total microorganisms of kimchi cabbage juice (KCJ) was reduced from log 6.53 CFU/g to log 3.69 CFU/g by washing with citric acid and ethanol, and lactic acid bacteria from log 4.40 CFU/g to log 2.01 CFU/g. The salinity of KCJ was appropriate for the growth of lactic acid bacteria but the pH was too low. The yield of washing, juice extraction, and total were 80.82%, 79.32%, and 64.11%, respectively. KCJ made by washing with citric acid and ethanol was good for the culture broth of lactic acid bacteria.