• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.207-209
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• 2002

A fraction of TRIGA contaminated soil whose decontamination is practicable by soil washing was about 34.2 %. It appeared from results of first decontamination experiment that decontamination efficiency using (NH$_4$)$_2$SO$_4$, H$_2$C$_2$O$_4$, and NaOH solution were high. Meanwhile, the most suitable ratio of contaminated soil mass(g) to decontamination solution volume(ml) appeared to be 1:10 according to experiment results. And the most suitable concentration of oxalic acid used as a decontamination solution appeared to be 0.5 M.

• Journal of agricultural medicine and community health
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• v.21 no.2
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• pp.159-171
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• 1996

It is investigated to determine the removal efficiency of organic - phosphorus insecticide residues in lettuce by washing processes, the 5 washing solution (stagnant tap water, flowing tap water, alkaline solution, acidic solution) were used with the washing time(10, 30, 50sec) and frequencies(1, 2, 3 washing, 2 rinsing). The removal efficiency of residual pesticides by 5 washing methods was increased on the more washing time and frequency, and also was the highest on the 3 times washing for each 50 sec. The removal rate with stagnant tap water was 33.7% of Diazinon, 45.7% of Dimethoate and 24.6% of Fenitrothion, but 29.4% of Diazinon, 37.7% of Dimethoate and 24.5% of Fenitrothion with flowing tap water. Therefore, the former was significantly higher effective than the latter one. The removal rate of residual pesticides with alkaline solution showed 32.1% of Diazinon, 49.5% of Dimethoate and 29.9% of Fenitrothion, and 30.4% of Diazinon, 36.4% of Dimethoate and 21.0% of Fenitrothion with acidic solution. The washing efficiency of neutral detergent showed the most effective result than others with 47.1% of Diazinon, 58.0% of Dimethoate and 39.5% of Fenitrothion. Consequently, it's appeared that the neural detergent washing was the most effective method on the 3 times washing for each 50 sec.

• Journal of Soil and Groundwater Environment
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• v.19 no.4
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• pp.45-51
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• 2014

In accordance with the view on remediated soil as a resource, this study assessed the applicability of soil washing with the neutral phosphate for remediation of arsenic (As)-contaminated soil. Three soil samples of different land uses (i.e., rice paddy, upland field and forest land) were collected from the study site, and the aqua regia-extractable As concentrations were 59.2, 30.8 and 53.1 mg/kg, respectively. Among the neutral phosphate reagents, ammonium phosphate showed the highest As washing efficiency. The optimized washing condition was 2-hr washing with 0.5M ammonium phosphate solution (pH 6) and soil to liquid ratio of 1 : 5. The extraction efficiencies of As did not guarantee the residual soil As concentrations to satisfy the Korea soil regulatory level (i.e., Worrisome level) in the three soil samples. To enhance washing efficiency, the As-contaminated soil was submerged in washing solution (1 : 1, w/v) for 24 hr and 1-hr washing with 0.5M ammonium phosphate solution was tested. As extraction efficiencies of 36.1 (rice paddy), 21.4 (upland field) and 26.4% (forest land) were attained, which satisfied the Worrisome level for Region 1 (25 mg/kg of As) in rice paddy, but not in upland field and forest land.

• 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.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.205-208
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• 2001

The bitterness of brewers yeast slurry decreased by washing with mild caustic soda solution followed by washing with 0.85% (w/v) NaCl solution The higher concentration of caustic soda was, the lower the bitterness unit(BU) of washed yeast slurry was. The lethal rate of yeast cells increased. When the concentration of caustic soda solution increased from 0.05%(w/v) to 0.25%(w/v), the BU of brewers yeast slurry was decreased from 45 to 3, but yeast cells viability decreased from 93% to 0%. The optimum washing conditions of brewers yeast slurry were as follows: the concentration of caustic soda solution was $0.07{\sim}0.1%$(w/v) and the contact time of brewers yeast slurry with caustic soda was $10{\sim}20$ minutes. The similar washing effect was obtained when the brewers yeast slurry was washed with 20%(v/v) ethanol solution.

• 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.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.389-395
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• 2024

The purpose of this study was to evaluate the effect of different washing solvents and washing methods on the flexural strength of 3D printed temporary resin. A bar(25 × 2 × 2 mm) was produced with a layer thickness of 50 ㎛ using an LCD-type 3D printer and divided into 15 groups(n = 10, each) according to washing solution(IPA; 99% isopropyl alcohol, TPM; 93% Tripropylene glycol monomethylether, ETL; Ethanol, TWC; Twin 3D Cleaner, and DNC; DIO navi Cleaner) and washing method(Dip; Dip washing, Ultra; Ultrasonic washing, and Auto; Automated washing). All groups were washed for 5 minutes, and post-cured for 5 minutes using a UV LED light curing machine. The Flexural strength was measured using a three-point bending test using a universal testing machine. For statistical analysis, one-way ANOVA, Tukey HSD post hoc test, Kruskal-Wallis test and post-hoc by Bonferroni-Dunn test(𝛼=.05) were performed depending on whether the normality test was satisfied. In all washing solvents except TPM and DNC, the Dip group showed the lowest flexural strength values, while the Auto group showed the highest flexural strength values except for DNC. Additionally, the washing solution showed completely different flexural strength values depending on the washing method.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.81-82
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• 2009

IEC 60456 declared the cocoa soiled cloth to be one of the standard soiled test cloths for measuring the performance of the clothes washing machines. Researchers for textile washing have known that cocoa soiled cloth has shown unpredictable washing performance. The color of cocoa mainly comes from flavonoids, and flavonoids reversibly change color with alkalinity from pH 1 to pH 7 as food colorants. The color change of flavonoids under various washing conditions, in the alkali solution, has not yet been confirmed. In this study, we have investigated the color change and the soil removal of the cocoa soiled cloth which were washed with alkaline washing liquids of various hardnesses. The cocoa soiled cloth which was washed in the water which was 60ppm or higher became darker than the soiled cloth. When the cloth was washed in the detergent solution, the cloth was slightly darker only when the washing condition was $20^{\circ}$ and 250ppm. As the water hardness increased, the soil removal decreased and the higher washing temperature was more effective.

• Membrane and Water Treatment
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• v.9 no.3
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• pp.137-146
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• 2018

Soil washing is one of the most frequently used remediation technologies for heavy metal-contaminated soils. Inorganic and organic acids and chelating agents that can enhance the removal of heavy metals from contaminated soils have been employed as soil washing agents. However, the toxicity, low removal efficiency and high cost of these chemicals limit their use. Given that humic substance (HS) can effectively chelate heavy metals, the development of an eco-friendly, performance-efficient and cost-effective soil washing agent using a nano-scale chelator composed of HS was examined in this study. Copper (Cu) and lead (Pb) were selected as target heavy metals. In soil washing experiments, HS concentration, pH, soil:washing solution ratio and extraction time were evaluated with regard to washing efficiency and the chelation effect. The highest removal rates by soil washing (69% for Cu and 56% for Pb) were achieved at an HS concentration of 1,000 mg/L and soil:washing solution ratio of 1:25. Washing with HS was found to be effective when the pH value was higher than 8, which can be attributed to the increased chelation effect between HS and heavy metals at the high pH range. In contrast, the washing efficiency decreased markedly in the low pH range due to HS precipitation. The chelation capacities for Cu and Pb in the aqueous phase were determined to be 0.547mmol-Cu/g-HS and 0.192mmol-Pb/g-HS, respectively.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.8-19
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• 2008

The physicochemical properties of soils having high uranium content, located around Duckpyungri in Korea, were investigated and the lab scale soil washing experiments to remove uranium from the soil were preformed with several washing solutions and on various washing conditions. SPLP (Synthetic Precipitation Leaching Procedure), TCLP (Toxicity Characteristic Leaching Procedure), and SEP (Sequential Extraction Procedure) for the soil were conducted and the uranium concentration of the extracted solution in SPLP was higher than Drinking Water Limit of USEPA (30 ${\mu}g$/L), suggesting that the continuous dissolution of uranium from soil by the weak acid rain may generate the environmental pollution around the research area. For the soil washing experiments, the uranium removal efficiency of pH 1 solution for S2 soil was about 80 %, but dramatically decreased as pH of solution was > 2, suggesting that strong acidic solutions are available to remove uranium from the soil. For solutions with 0.1M of HCl and 0.05 M of ${H_2}{SO_4}$, their removal efficiencies at 1 : 1 of soil vs. washing solution ratio were higher than 70%, but the removal efficiencies of acetic acid, and EDTA were below 30%. At 1 : 3 of soil vs. solution, the uranium removal efficiencies of 0.1M HCl, 0.05 M ${H_2}{SO_4}$, and 0.5M citric acid solution increased to 88%, 100%, and 61% respectively. On appropriate washing conditions for S2 soil such as 1 : 3 ratio for the soil vs. solution ratio, 30 minute for washing time, and 2 times continuous washing, TOC (Total Organic Contents) and CEC (Cation Exchange Capacity) for S2 soil were measured before/after soil washing and their XRD (X-Ray Diffraction) and XRF (X-Ray Fluorescence) results were also compared to investigate the change of soil properties after soil washing. TOC and CEC decreased by 55% and 66%, compared to those initial values of S2 soil, suggesting that the soil reclaimant may need to improve the washed soils for the cultivated plants. Results of XRF and XRD showed that the structural change of soil after soil washing was insignificant and the washed soil will be partially used for the further purpose.