Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remov...Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remove discrete particles or metal-bearing particles and/or chemical extraction based on leaching or dissolving process to extract the metals from the soils into an aqueous solution. However, washwater remained from soil washing process contains discrete particulate particles along with heavy metals as solution phase to be treated separately, as well as this process can produce large amount of sludge that requires further treatment, slow metal precipitation, poor settling, the aggregation of metal precipitates. Electrical treatments including electrocoagulation and electrolysis can be effective in removing these substances from washwater. This paper reviews the theoretical models in applying electrocoagulation and electrolysis to remove heavy metals and discrete particulate particles in washwater by examining and comparing the status of washwater treatment technologies which have been undertaken, mostly in the US and EU for the period 1990-2012.展开更多
An old automotive industrial site located at Mexico City with many years of operation and contaminated with heavy oil hydrocarbons, particularly spent oils, was assessed for restoration using the surfactant enhanced s...An old automotive industrial site located at Mexico City with many years of operation and contaminated with heavy oil hydrocarbons, particularly spent oils, was assessed for restoration using the surfactant enhanced soil washing (SESW) process. The main goal of this study was to characterize the contaminated soil in terms of TPHs, BTEX, PAHs, and metals contents as well as microbiologically (total heterotrophs and specific degrading microorganisms). We also aimed to determine the surfactant type and concentration to be used in the SESW process for the automotive waste oil contaminated soil. At the end, sixteen kg of contaminated soil were washed and the produced wastewater (approximately 40 L) was characterized in terms of COD, BOD;solids, and other physico-chemical parameters. The soil contained about 14,000 mg of TPH/kg soil (heavy fraction), 0.13 mg/kg of benzo (k) fluoranthene and 0.07 mg/kg of benzo (a) pyrene as well as traces of some metals. Metals concentrations were always under the maximum concentration levels suggested by Mexican regulations. 15 different surfactants were used to identify the one with the capability to achieve the highest TPH removal. Surfactants included 5 anionics, 2 zwitterionic, 5 nonionics and 3 natural gums. Sulfopon 30 at a concentration of 0.5% offered the best surfactant performance. The TPH removals employing the different surfactants were in the range from 38% to 68%, in comparison to the soil washing with water (10% of TPH removal). Once the surfactant was selected, 70 kg of soil were washed and the resulting water contained approximately 1300 mg/L of COD, 385 mg/L of BOD (BOD/COD = 0.29), 122 mg/L of MBAS, and 212 mg/L of oil and greases, among other contaminants.展开更多
[Objectives] To summarize the characteristics of washing salinity by irrigation in Hetao Irrigation District, and propose the empirical framework of washing salinity by irrigation to maintain soil quality, and provide...[Objectives] To summarize the characteristics of washing salinity by irrigation in Hetao Irrigation District, and propose the empirical framework of washing salinity by irrigation to maintain soil quality, and provide a theoretical basis for maintaining the sustainable development of soil in Hetao Irrigation District. [Methods] The methods of experiment, questionnaire, on-the-spot investigation and literature review were used. [Results] This study proposed the empirical framework of washing salinity by irrigation to maintain soil quality in Hetao Irrigation District. Seven factors of the framework, including flood irrigation, land leveling, plastic film mulching, fertilization, soil organic matter, pH and salinity, and their relationships were determined. The characteristics of these factors in Hetao Irrigation District were investigated(flooding irrigation with a large amount of irrigation water, high amount of fertilizer application, low organic matter, high pH, large variation of salinity, etc.). The mechanisms and effects of various factors affecting soil quality in Hetao Irrigation District were analyzed(the mean soil organic matter(SOM) and pH were kept in the range of 10.9-13.9 g/kg and 8.0-8.15 in recent 35 years, respectively, and increased slightly, etc.). [Conclusions] The empirical framework can be used as a theoretical norm for evaluating soil quality under the condition of washing salinity by irrigation. Under the condition of washing salinity by irrigation, the agricultural soil quality in Hetao Irrigation District showed a stable trend over time. Using this framework, we can find soil problems, and adjust some unbalanced factors to maintain the stability of soil quality in Hetao Irrigation District, and can also provide a reference for other areas.展开更多
The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution.However,the complex environment of soil and the competitive behavior of leaching chemi...The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution.However,the complex environment of soil and the competitive behavior of leaching chemicals considerably restrain adsorption capacity of adsorbent material during washing process,which demands a higher resistance of the adsorbents to interference.In this study,we synthesized strongly magnetic,high specific surface area(573.49 m^(2)/g)UiO66 composites(i.e.,UiO66-Fe_(3)O_(4))using hydrothermal process.The UiO66-Fe_(3)O_(4) was applied as an adsorbent during the ethylene diamine tetraacetic acid(EDTA)-assisted washing process of contaminated soil.The incorporation of UiO66-Fe_(3)O_(4)results in rapid heavy metal removal and recovery from the soil under low concentrations of washing agent(0.001 mol/L)with reduced residual heavy metal mobility of soil after remediation.Furthermore,UiO66-Fe_(3)O_(4)can quickly recollect by an external magnet,which offers a simple and inexpensive recovery method for heavy metals from contaminated soil.Overall,UiO66-Fe_(3)O_(4)configuration with EDTA-assisted washing process showed opportunities for heavy metals contaminated sites.展开更多
A sophorolipids(SLs)micro-emulsion in Winsor type Ⅰ form was used for crude oil contaminated soil washing treatment.The micro-emulsion shows higher oil removal rate than SLs aqueous solution and diesel oil.The type ...A sophorolipids(SLs)micro-emulsion in Winsor type Ⅰ form was used for crude oil contaminated soil washing treatment.The micro-emulsion shows higher oil removal rate than SLs aqueous solution and diesel oil.The type Ⅰ micro-emulsion with w(SLs)=6%,w(NaCl)=1%,w(diesel)=13.36% gave a high oil removal rate of 95.6% and the eluate remained in type Ⅰ state.The recovered oil showed lower viscosity,mainly caused by the entering of diesel from the micro-emulsion phase into the oil phase and the lower removal rate of the heavier components,such as the resin and asphaltene.The initial heavily saline-alkaline soil changed into mildly saline-alkaline state after washing treatment,favoring the germination and growth of plants,with ryegrass showing better germination and growth effect than alfalfa.The ryegrass showed good phytoremediation effect on the contaminated soil after SLs micro-emulsion washing.The combination process of SL micro-emulsion washing and ryegrass phytoremediation is prospective for oily soil treatment.展开更多
It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant e...It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant extraction efficiency of traditional pumping and treating, which is a typical washing technology for the remediation of contaminated soils, with methods that utilize freeze-thaw cycles. In the soil freezing process, water shifts from unfrozen soils to the freezing front, and the permeability of soil will be enhanced under certain temperature gradients and water conditions. Therefore, this paper discusses the purification of contaminated soil through freeze-thaw action. We conducted a cleansing experiment on clay and silica sand infused with NaCl（simulation of heavy metals） and found that the efficiency of purification was enhanced remarkably in the latter by the freeze-thaw action. To assess the effective extraction of DNAPLs in soil, we conducted an experiment on suction by freezing, predicated on the different freezing points of moisture and pollutants. We found that the permeability coefficient was significantly increased by the freezing-thawing action, enabling the DNAPL contaminants to be extracted selectively and effectively.展开更多
Coal preparation solid waste,which is a major environmental issue for coal-producing areas in China,may be microbiologically digested and transformed into a product suitable as a soil amendment to increase soil organi...Coal preparation solid waste,which is a major environmental issue for coal-producing areas in China,may be microbiologically digested and transformed into a product suitable as a soil amendment to increase soil organic matter content and prevent and enhance plant/crop growth.Coal preparation waste collected from a coal sorting plant in Inner Mongolia,China was digested in bioreactors inoculated with microbial enrichments prepared from activated sludge and cow manure.The effluent solids from the coal preparation waste bioreactors were analyzed for their suitability as organic soil amendments,which complied with China standards.Plant growth tests were conducted in sandy soil from a semi-arid region in Colorado,which was amended with the effluent solids.Kentucky bluegrass(Poa pratensis L.)and chives(Allium schoenoprasum)were used as the representative plants for the growth tests,where results indicated substantially higher yields of Kentucky bluegrass and chives for the sandy soils amended with the effluent solids when compared to a commercial organic fertilizer.The number and average length of Kentucky bluegrass shoots were 10 and 5.1 times higher,respectively,in soils amended with the effluent solids.Similarly,the number and average length of chives shoots were 10 and 1.7 times higher,respectively,in soils amended with the effluent solids.Overall,the microbial digestion of coal preparation waste for application as an organic soil amendment is a viable alternative and beneficial use of coal preparation solid waste.展开更多
Potentially toxic metals,Cd and Pb in paddy soil,have important meanings for safety of rice.A comparison extraction of Cd and Pb with EDTA,DTPA,citric acid,and FeCl3 and effects on soil fertility was studied.Results i...Potentially toxic metals,Cd and Pb in paddy soil,have important meanings for safety of rice.A comparison extraction of Cd and Pb with EDTA,DTPA,citric acid,and FeCl3 and effects on soil fertility was studied.Results indicate that about 59%and 63%of soil Cd and Pb were simultaneously removed by 10 g/L EDTA at pH 5 with a soil/extractant ratio of 1:10(W/V)for 30 min while 52%and 51%by 5 g/L DTPA.Acid extractable and reducible Cd by EDTA and DTPA contributed 58%and 53%of the removals and acid extractable and reducible Pb were about 49%and 41%,respectively.Slight changes of soil fertility,including pH,cation exchange capacity,organic matter,and soil extractable phosphorus,were observed.Extractions of citric acid and ferric chloride,however,were only efficient for Cd and the soil pH was decreased significantly.This study suggests that EDTA and DTPA can be considered as suitable agents to clean up the paddy soils contaminated with potentially toxic metals.展开更多
The accumulation of heavy metals in soil is a serious environmental problem. It is well known that heavy metals have an affinity for different compartments of soil. The risk associated with the presence of metals in s...The accumulation of heavy metals in soil is a serious environmental problem. It is well known that heavy metals have an affinity for different compartments of soil. The risk associated with the presence of metals in soil is the ability of their transfer in water or plants. In the present research, batch extraction experiments were conducted using acetic acid (AA) as an extractant solution at various concentrations and contact times to determine the best conditions of soil washing process to achieve high heavy metal removal efficiencies. AA was investigated for its applicability for the removal of lead, cadmium and nickel from soil. Batch soil washing experiments were performed on 1.0 g portions of the spiked soil using different concentrations (0.001, 0.005, 0.01, 0.05, and 0.1 mol/L) of AA (CH3COOH) with solid: liquid ratio of 1:10. The results showed that AA extracted greater Pb than Cd and Ni. The extraction was carried out with shaking times from 15 to 180 min. The removal percentage of Pb varies from 42.2%-100% and Cd from 5.2%-31.1% with increasing concentration of AA, while the removal efficiency of Ni was not exceeded about 1%. Comparing with Pb and Cd, the removal efficiency of Ni was very low;this means that the solubility of Ni in AA was very low. It was found that 0.1 mol/L AA for soil washing was effective in removing absorbed Pb from contaminated soil (100% efficiency) at time 15 min. While the efficiency reaching 100% with washing solution of 0.05 and 0.01 mol/L at times 120 and 180 min, respectively. The efficiencies of Cd and Ni extraction were improved when 1 mol/L of AA solution was used (41.3% to 70.6% for Cd and 16.3% to 23.3% for Ni).展开更多
This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The ...This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The field soil contained concentrations of Pb (307.31 mg⋅kg−1), Zn (207.77 mg⋅kg−1) and Cr (447.50 mg⋅kg−1). Both (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water were found to be effective on removing (Na2S2O5) Pb, Cr and Zn respectively. (Na2S2O5) + (0.1 HCl) Cr, Zn and Pb respectively. Sulfur Pb, Cr and Zn respectively. The removal rate of Pb, Zn, and Cr varied from 10.35% - 26%, 3.4% - 21.60% and 4.97% - 23.88% for (0.01 M Na2S2O5 respectively. The removal rate of Pb, Zn, and Cr varied from 16.13% - 20.07%, 8.20% - 23.48%, 5.42% - 28.93% for (0.01 M Na2S2O5 + 0.1 M HCl) respectively. The removal rate of Pb, Zn, and Cr varied from 10.20% - 25.5%, 9.55% - 25.13% and 6.04% - 25.54% for (S) respectively.展开更多
文摘Soil washing, ex situ mechanical technique, is one of the few permanent treatment alternatives to remove metal contaminants from soils by employing physical separation based on mineral processing technologies to remove discrete particles or metal-bearing particles and/or chemical extraction based on leaching or dissolving process to extract the metals from the soils into an aqueous solution. However, washwater remained from soil washing process contains discrete particulate particles along with heavy metals as solution phase to be treated separately, as well as this process can produce large amount of sludge that requires further treatment, slow metal precipitation, poor settling, the aggregation of metal precipitates. Electrical treatments including electrocoagulation and electrolysis can be effective in removing these substances from washwater. This paper reviews the theoretical models in applying electrocoagulation and electrolysis to remove heavy metals and discrete particulate particles in washwater by examining and comparing the status of washwater treatment technologies which have been undertaken, mostly in the US and EU for the period 1990-2012.
文摘An old automotive industrial site located at Mexico City with many years of operation and contaminated with heavy oil hydrocarbons, particularly spent oils, was assessed for restoration using the surfactant enhanced soil washing (SESW) process. The main goal of this study was to characterize the contaminated soil in terms of TPHs, BTEX, PAHs, and metals contents as well as microbiologically (total heterotrophs and specific degrading microorganisms). We also aimed to determine the surfactant type and concentration to be used in the SESW process for the automotive waste oil contaminated soil. At the end, sixteen kg of contaminated soil were washed and the produced wastewater (approximately 40 L) was characterized in terms of COD, BOD;solids, and other physico-chemical parameters. The soil contained about 14,000 mg of TPH/kg soil (heavy fraction), 0.13 mg/kg of benzo (k) fluoranthene and 0.07 mg/kg of benzo (a) pyrene as well as traces of some metals. Metals concentrations were always under the maximum concentration levels suggested by Mexican regulations. 15 different surfactants were used to identify the one with the capability to achieve the highest TPH removal. Surfactants included 5 anionics, 2 zwitterionic, 5 nonionics and 3 natural gums. Sulfopon 30 at a concentration of 0.5% offered the best surfactant performance. The TPH removals employing the different surfactants were in the range from 38% to 68%, in comparison to the soil washing with water (10% of TPH removal). Once the surfactant was selected, 70 kg of soil were washed and the resulting water contained approximately 1300 mg/L of COD, 385 mg/L of BOD (BOD/COD = 0.29), 122 mg/L of MBAS, and 212 mg/L of oil and greases, among other contaminants.
基金Supported by Natural Science Foundation of Inner Mongolia Autonomous Region (2020MS04001)Science and Technology Research Program of Hetao University (HYZX201952)Talent Introduction Startup Program of Hetao University (HYRC2019006)。
文摘[Objectives] To summarize the characteristics of washing salinity by irrigation in Hetao Irrigation District, and propose the empirical framework of washing salinity by irrigation to maintain soil quality, and provide a theoretical basis for maintaining the sustainable development of soil in Hetao Irrigation District. [Methods] The methods of experiment, questionnaire, on-the-spot investigation and literature review were used. [Results] This study proposed the empirical framework of washing salinity by irrigation to maintain soil quality in Hetao Irrigation District. Seven factors of the framework, including flood irrigation, land leveling, plastic film mulching, fertilization, soil organic matter, pH and salinity, and their relationships were determined. The characteristics of these factors in Hetao Irrigation District were investigated(flooding irrigation with a large amount of irrigation water, high amount of fertilizer application, low organic matter, high pH, large variation of salinity, etc.). The mechanisms and effects of various factors affecting soil quality in Hetao Irrigation District were analyzed(the mean soil organic matter(SOM) and pH were kept in the range of 10.9-13.9 g/kg and 8.0-8.15 in recent 35 years, respectively, and increased slightly, etc.). [Conclusions] The empirical framework can be used as a theoretical norm for evaluating soil quality under the condition of washing salinity by irrigation. Under the condition of washing salinity by irrigation, the agricultural soil quality in Hetao Irrigation District showed a stable trend over time. Using this framework, we can find soil problems, and adjust some unbalanced factors to maintain the stability of soil quality in Hetao Irrigation District, and can also provide a reference for other areas.
基金supported by the University Basic Research Fund of China(No.2232020A-10)the Joint Foundation of Iron and Steel,National Natural Science Foundation of China(No.U1660107)。
文摘The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution.However,the complex environment of soil and the competitive behavior of leaching chemicals considerably restrain adsorption capacity of adsorbent material during washing process,which demands a higher resistance of the adsorbents to interference.In this study,we synthesized strongly magnetic,high specific surface area(573.49 m^(2)/g)UiO66 composites(i.e.,UiO66-Fe_(3)O_(4))using hydrothermal process.The UiO66-Fe_(3)O_(4) was applied as an adsorbent during the ethylene diamine tetraacetic acid(EDTA)-assisted washing process of contaminated soil.The incorporation of UiO66-Fe_(3)O_(4)results in rapid heavy metal removal and recovery from the soil under low concentrations of washing agent(0.001 mol/L)with reduced residual heavy metal mobility of soil after remediation.Furthermore,UiO66-Fe_(3)O_(4)can quickly recollect by an external magnet,which offers a simple and inexpensive recovery method for heavy metals from contaminated soil.Overall,UiO66-Fe_(3)O_(4)configuration with EDTA-assisted washing process showed opportunities for heavy metals contaminated sites.
基金financial support of National Natural Science Foundation of China(22078366)。
文摘A sophorolipids(SLs)micro-emulsion in Winsor type Ⅰ form was used for crude oil contaminated soil washing treatment.The micro-emulsion shows higher oil removal rate than SLs aqueous solution and diesel oil.The type Ⅰ micro-emulsion with w(SLs)=6%,w(NaCl)=1%,w(diesel)=13.36% gave a high oil removal rate of 95.6% and the eluate remained in type Ⅰ state.The recovered oil showed lower viscosity,mainly caused by the entering of diesel from the micro-emulsion phase into the oil phase and the lower removal rate of the heavier components,such as the resin and asphaltene.The initial heavily saline-alkaline soil changed into mildly saline-alkaline state after washing treatment,favoring the germination and growth of plants,with ryegrass showing better germination and growth effect than alfalfa.The ryegrass showed good phytoremediation effect on the contaminated soil after SLs micro-emulsion washing.The combination process of SL micro-emulsion washing and ryegrass phytoremediation is prospective for oily soil treatment.
基金supported by the National Natural Science Foundation of China (No. 41371092)the Scientific Research Foundation for Returned Overseas Students+1 种基金the Education Department of Henan Province Science and Technology Research projects (No.14B170007)the doctoral foundation of Henan Polytechnic University (No. 648349)
文摘It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant extraction efficiency of traditional pumping and treating, which is a typical washing technology for the remediation of contaminated soils, with methods that utilize freeze-thaw cycles. In the soil freezing process, water shifts from unfrozen soils to the freezing front, and the permeability of soil will be enhanced under certain temperature gradients and water conditions. Therefore, this paper discusses the purification of contaminated soil through freeze-thaw action. We conducted a cleansing experiment on clay and silica sand infused with NaCl（simulation of heavy metals） and found that the efficiency of purification was enhanced remarkably in the latter by the freeze-thaw action. To assess the effective extraction of DNAPLs in soil, we conducted an experiment on suction by freezing, predicated on the different freezing points of moisture and pollutants. We found that the permeability coefficient was significantly increased by the freezing-thawing action, enabling the DNAPL contaminants to be extracted selectively and effectively.
基金The authors declare that the work of Co-author Dr.Liang Chen was partially supported by the National Key R&D Program of China(2016YFC0401405)the National Natural Science Foundation of China(No.41772245).
文摘Coal preparation solid waste,which is a major environmental issue for coal-producing areas in China,may be microbiologically digested and transformed into a product suitable as a soil amendment to increase soil organic matter content and prevent and enhance plant/crop growth.Coal preparation waste collected from a coal sorting plant in Inner Mongolia,China was digested in bioreactors inoculated with microbial enrichments prepared from activated sludge and cow manure.The effluent solids from the coal preparation waste bioreactors were analyzed for their suitability as organic soil amendments,which complied with China standards.Plant growth tests were conducted in sandy soil from a semi-arid region in Colorado,which was amended with the effluent solids.Kentucky bluegrass(Poa pratensis L.)and chives(Allium schoenoprasum)were used as the representative plants for the growth tests,where results indicated substantially higher yields of Kentucky bluegrass and chives for the sandy soils amended with the effluent solids when compared to a commercial organic fertilizer.The number and average length of Kentucky bluegrass shoots were 10 and 5.1 times higher,respectively,in soils amended with the effluent solids.Similarly,the number and average length of chives shoots were 10 and 1.7 times higher,respectively,in soils amended with the effluent solids.Overall,the microbial digestion of coal preparation waste for application as an organic soil amendment is a viable alternative and beneficial use of coal preparation solid waste.
基金Project(2015BAD05B02)supported by the National Science and Technology Support Program,China
文摘Potentially toxic metals,Cd and Pb in paddy soil,have important meanings for safety of rice.A comparison extraction of Cd and Pb with EDTA,DTPA,citric acid,and FeCl3 and effects on soil fertility was studied.Results indicate that about 59%and 63%of soil Cd and Pb were simultaneously removed by 10 g/L EDTA at pH 5 with a soil/extractant ratio of 1:10(W/V)for 30 min while 52%and 51%by 5 g/L DTPA.Acid extractable and reducible Cd by EDTA and DTPA contributed 58%and 53%of the removals and acid extractable and reducible Pb were about 49%and 41%,respectively.Slight changes of soil fertility,including pH,cation exchange capacity,organic matter,and soil extractable phosphorus,were observed.Extractions of citric acid and ferric chloride,however,were only efficient for Cd and the soil pH was decreased significantly.This study suggests that EDTA and DTPA can be considered as suitable agents to clean up the paddy soils contaminated with potentially toxic metals.
文摘The accumulation of heavy metals in soil is a serious environmental problem. It is well known that heavy metals have an affinity for different compartments of soil. The risk associated with the presence of metals in soil is the ability of their transfer in water or plants. In the present research, batch extraction experiments were conducted using acetic acid (AA) as an extractant solution at various concentrations and contact times to determine the best conditions of soil washing process to achieve high heavy metal removal efficiencies. AA was investigated for its applicability for the removal of lead, cadmium and nickel from soil. Batch soil washing experiments were performed on 1.0 g portions of the spiked soil using different concentrations (0.001, 0.005, 0.01, 0.05, and 0.1 mol/L) of AA (CH3COOH) with solid: liquid ratio of 1:10. The results showed that AA extracted greater Pb than Cd and Ni. The extraction was carried out with shaking times from 15 to 180 min. The removal percentage of Pb varies from 42.2%-100% and Cd from 5.2%-31.1% with increasing concentration of AA, while the removal efficiency of Ni was not exceeded about 1%. Comparing with Pb and Cd, the removal efficiency of Ni was very low;this means that the solubility of Ni in AA was very low. It was found that 0.1 mol/L AA for soil washing was effective in removing absorbed Pb from contaminated soil (100% efficiency) at time 15 min. While the efficiency reaching 100% with washing solution of 0.05 and 0.01 mol/L at times 120 and 180 min, respectively. The efficiencies of Cd and Ni extraction were improved when 1 mol/L of AA solution was used (41.3% to 70.6% for Cd and 16.3% to 23.3% for Ni).
文摘This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The field soil contained concentrations of Pb (307.31 mg⋅kg−1), Zn (207.77 mg⋅kg−1) and Cr (447.50 mg⋅kg−1). Both (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water were found to be effective on removing (Na2S2O5) Pb, Cr and Zn respectively. (Na2S2O5) + (0.1 HCl) Cr, Zn and Pb respectively. Sulfur Pb, Cr and Zn respectively. The removal rate of Pb, Zn, and Cr varied from 10.35% - 26%, 3.4% - 21.60% and 4.97% - 23.88% for (0.01 M Na2S2O5 respectively. The removal rate of Pb, Zn, and Cr varied from 16.13% - 20.07%, 8.20% - 23.48%, 5.42% - 28.93% for (0.01 M Na2S2O5 + 0.1 M HCl) respectively. The removal rate of Pb, Zn, and Cr varied from 10.20% - 25.5%, 9.55% - 25.13% and 6.04% - 25.54% for (S) respectively.
