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首页> 外文期刊>Journal of Environmental Science and Health. A, Toxic/Hazardous Substances & Environmental Engineering >Effect of oxidant dosage on integrated electrochemical remediation of contaminant mixtures in soils
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Effect of oxidant dosage on integrated electrochemical remediation of contaminant mixtures in soils

机译：氧化剂用量对土壤中污染物混合物综合电化学修复的影响

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Many sites are contaminated with contaminant mixtures, commonly heavy metals and polycyclic aromatic hydrocarbons (PAHs), which pose a great challenge for remediation. The objective of this research was to investigate coupled Fenton-like oxidation and electrokinetic remediation of low permeability soils contaminated with both heavy metals and PAHs. This remediation process aims at simultaneous oxidation of organic contaminants and removal of heavy metals. Fenton's reagent, consisting of hydrogen peroxide (H_2O_2) and native iron catalyst, is utilized for chemical oxidation. Laboratory batch and electrokinetic experiments were performed on kaolin (a low permeability soil) spiked with nickel and phenanthrene each at a concentration of 500 mg/kg of dry soil to represent typical heavy metal and PAH contaminants found at contaminated sites. Experiments were conducted using H_2O_2 solution in 5%, 10%, 20% and 30% concentrations and also using deionized (DI) water as control. For electrokinetic experiments, a voltage gradient of 1 VDC/cm was applied and H_2O_2 solution was introduced at the anode for a total duration of four weeks. Batch tests showed that phenanthrene oxidation increases from 76% to 87% when the H_2O_2 concentration increases from 5% to 30%. The electrokinetic experiments showed substantial electroosmotic flow in all the tests. Approximately one pore volume of flow was generated in the DI baseline test and about 1.2-1.6 pore volumes were generated in case of H_2O_2 tests. Phenanthrene was partially oxidized in the H_2O_2 tests and its removal from the soil was insignificant. Oxidation of phenanthrene increased with increasing concentration of H_2O_2; a maximum of 56% oxidation was observed with 30% H_2O_2. Nickel migrated from anode to cathode. This migration was more pronounced in the H_2O_2 tests as compared to the DI baseline test. Nickel precipitated in all the tests near the cathode due to high pH conditions. These results emphasize that the optimization of H_2O_2/catalyst concentration and voltage gradient as well as the control of soil pH are required to increase the removal of nickel and the oxidation of phenanthrene.
机译：许多场所都受到污染物混合物的污染，通常是重金属和多环芳烃（PAHs），这给修复带来了巨大挑战。这项研究的目的是研究被重金属和多环芳烃污染的低渗透性土壤的类似芬顿氧化和电动修复。该修复过程旨在同时氧化有机污染物和去除重金属。 Fenton试剂由过氧化氢（H_2O_2）和天然铁催化剂组成，用于化学氧化。在掺有镍和菲的高岭土（低渗透性土壤）上分别进行了实验室分批和电动实验，浓度分别为500 mg / kg的干燥土壤，以代表在受污染地点发现的典型重金属和PAH污染物。使用浓度分别为5％，10％，20％和30％的H_2O_2溶液进行实验，还使用去离子（DI）水作为对照。对于电动实验，施加1 VDC / cm的电压梯度，并将H_2O_2溶液引入阳极，总时长为4周。分批测试表明，当H_2O_2浓度从5％增加到30％时，菲的氧化作用从76％增加到87％。电动实验在所有测试中均显示出大量的电渗流。在DI基准测试中产生了约一个孔体积的流量，在H_2O_2测试中产生了约1.2-1.6孔体积。在H_2O_2试验中，菲被部分氧化，从土壤中的去除并不重要。菲的氧化随着H_2O_2浓度的增加而增加。用30％H_2O_2观察到最大56％的氧化。镍从阳极迁移到阴极。与DI基准测试相比，这种迁移在H_2O_2测试中更为明显。在所有测试中，由于高pH条件，镍都会在阴极附近沉淀。这些结果强调，要增加镍的去除和菲的氧化，就需要优化H_2O_2 /催化剂的浓度和电压梯度以及控制土壤的pH值。

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