نوع مقاله : پژوهشی
نویسندگان
گروه مهندسی عمران - دانشگاه بوعلی سینا .
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In this paper, the influence of calcium carbonate (calcite) in kaolinite on the buffering capacity of clayey soils and soil contaminant remediation with EDTA is investigated. For this purpose, several mixtures of kaolinite and different percentages of carbonate were prepared and were laboratory contaminated with
different concentrations of $Pb(NO_{3})_{2}$. The kaolinite sample initially had 4% natural carbonate. To investigate the impact of carbonate on the soil interaction process with EDTA, 6, 11, 16, 21 and 26 percentages of calcite was added to soil samples. Therefore, different calcareous soil samples had 10, 15, 20, 25, and 30 percentage of calcite, respectively. Then, different concentrations of EDTA were applied to these samples in the EDTA/Pb ratios of 0.2 to 1. This range of EDTA is proposed by prior research. After the mixing period, the samples were centrifuged. Then, the concentration of Pb and Ca was measured in supernatant.
The results show that in this method of soil remediation, due to the solubility of a part of carbonate in low pH, the buffering capacity of soil decreases. With the solubility of calcium carbonate and the release of calcium ions, both calcium and Pb ions will tend to interact with EDTA and form a Ca-EDTA or Pb-EDTA complex. This, in turn, will reduce the efficiency of soil remediation with EDTA. The results of this paper show that the use of EDTA, at low concentrations, with the application of several soil washing will decrease the solubility of carbonate and consequently increase the efficiency of contaminant removal by EDTA from calcareous soils. In addition,
according to the results of this paper, several soil washing with low concentrations of EDTA will not significantly decrease the soil pH. Therefore, the soil buffering capacity will remain constant in this method of soil remediation. In fact, in such a case, the remediated soil will keep its retention capability after the remediation process.
کلیدواژهها [English]
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