By inducing the extraction by heavy metal acid and chelating reaction using organic acid such as citric acid, 1) there is no deformation of the soil structure, 2) it is harmless to the ecology after washing, and 3) it can be used to effectively remove heavy metals. The study was conducted and an on-...
By inducing the extraction by heavy metal acid and chelating reaction using organic acid such as citric acid, 1) there is no deformation of the soil structure, 2) it is harmless to the ecology after washing, and 3) it can be used to effectively remove heavy metals. The study was conducted and an on-site demonstration experiment was conducted to derive the appropriate washing conditions and to evaluate the washing efficiency for the conditions.
For heavy metal contaminated soil washing using organic acid and EDTA, use high-concentration complex heavy metal contaminated soil for continuous washing and analysis of residual heavy metal concentration in contaminated soil according to detergent type and detergent concentration to evaluate efficiency, and analyze SM&T before and after washing. Soil washing experiment for Pb-contaminated soil and Pb/Zn complex contaminated soil was performed by conducting a field-applied experiment on the appropriate cleanser derived from lab-scale experiments and actual on-site contaminated soil. And washing concentrations to perform additional experiments.
Among cleaning agents, NTA showed high cleaning ability for all heavy metals except As and Pb. EDTA showed excellent cleaning ability against As and Pb, and citric acid and malic acid are high cleaning agents. The washing ability is lower than that of EDTA and NTA, and the washing ability of Pb is relatively low. After washing, the relationship between the residual concentration (qe) in soil and the heavy metal concentration (Ce) in the washing agent during repeated washing was analyzed by applying a biphasic desorption model. The cleaning agents with excellent washing performance by type of washing agent were in the order of Malic acid In the case of high concentration Pb single contaminated soil, when citric acid (0.025 M) was used as a washing agent, the washing efficiency increased as the washing agent concentration increased, and EDTA (0.025 M) showed improved washing efficiency compared to citric acid at the same washing agent concentration. Pb removal efficiency was more than 50% at 1.525 hours or more at a washing time of 0.025 M. The washing time for the Pb/Zn complex soil was considered to be 1.0 to 1.5 hours, and the concentrations of Pb and Zn in the soil after washing were 35% and 40% for Pb and Zn in 0.025 M citric acid. When washing with 0.015 M citric acid, the washing efficiency increased with increasing L/S in soils with particle size Hcit / Nacit> Na-cit was found, and as a result of applying 0.4M Hcit, Pb was about 75% and Zn was 80% or more. However, the washing efficiency of Na-cit was less than 10%. In the organic acid washing, the washing efficiency was greatly influenced by the pH fluctuation according to the amount of the detergent injection. In conclusion, 0.4 M Hcit was found to be the most effective detergent concentration, but 0.1 M was selected as the optimal washing concentration in consideration of economic efficiency and efficiency. As a result of evaluating the washing efficiency according to the high-liquid ratio and the washing method, the washing time was found to be 30 minutes in the range of 3 to 5 high-liquid ratios, and repeat washing was repeated twice every 30 minutes at 0.1M Hcit and once every 1 hour washing. Similar washing efficiency was shown, but in other cases, repeated washing showed better washing efficiency. Therefore, it is considered to be advantageous to perform repeated washing.
By inducing the extraction by heavy metal acid and chelating reaction using organic acid such as citric acid, 1) there is no deformation of the soil structure, 2) it is harmless to the ecology after washing, and 3) it can be used to effectively remove heavy metals. The study was conducted and an on-site demonstration experiment was conducted to derive the appropriate washing conditions and to evaluate the washing efficiency for the conditions.
For heavy metal contaminated soil washing using organic acid and EDTA, use high-concentration complex heavy metal contaminated soil for continuous washing and analysis of residual heavy metal concentration in contaminated soil according to detergent type and detergent concentration to evaluate efficiency, and analyze SM&T before and after washing. Soil washing experiment for Pb-contaminated soil and Pb/Zn complex contaminated soil was performed by conducting a field-applied experiment on the appropriate cleanser derived from lab-scale experiments and actual on-site contaminated soil. And washing concentrations to perform additional experiments.
Among cleaning agents, NTA showed high cleaning ability for all heavy metals except As and Pb. EDTA showed excellent cleaning ability against As and Pb, and citric acid and malic acid are high cleaning agents. The washing ability is lower than that of EDTA and NTA, and the washing ability of Pb is relatively low. After washing, the relationship between the residual concentration (qe) in soil and the heavy metal concentration (Ce) in the washing agent during repeated washing was analyzed by applying a biphasic desorption model. The cleaning agents with excellent washing performance by type of washing agent were in the order of Malic acid In the case of high concentration Pb single contaminated soil, when citric acid (0.025 M) was used as a washing agent, the washing efficiency increased as the washing agent concentration increased, and EDTA (0.025 M) showed improved washing efficiency compared to citric acid at the same washing agent concentration. Pb removal efficiency was more than 50% at 1.525 hours or more at a washing time of 0.025 M. The washing time for the Pb/Zn complex soil was considered to be 1.0 to 1.5 hours, and the concentrations of Pb and Zn in the soil after washing were 35% and 40% for Pb and Zn in 0.025 M citric acid. When washing with 0.015 M citric acid, the washing efficiency increased with increasing L/S in soils with particle size Hcit / Nacit> Na-cit was found, and as a result of applying 0.4M Hcit, Pb was about 75% and Zn was 80% or more. However, the washing efficiency of Na-cit was less than 10%. In the organic acid washing, the washing efficiency was greatly influenced by the pH fluctuation according to the amount of the detergent injection. In conclusion, 0.4 M Hcit was found to be the most effective detergent concentration, but 0.1 M was selected as the optimal washing concentration in consideration of economic efficiency and efficiency. As a result of evaluating the washing efficiency according to the high-liquid ratio and the washing method, the washing time was found to be 30 minutes in the range of 3 to 5 high-liquid ratios, and repeat washing was repeated twice every 30 minutes at 0.1M Hcit and once every 1 hour washing. Similar washing efficiency was shown, but in other cases, repeated washing showed better washing efficiency. Therefore, it is considered to be advantageous to perform repeated washing.
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