QE331 : Assessment of soil chemical washing method for Pb-Zn removal from soils around the Bama mine complex
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2017
Authors:
Mehrnoosh nazari moghaddam [Author], Giti Forghani Tehrani[Supervisor], Afshin Qishlaqi[Advisor]
Abstarct: The lead and zinc mine in Irankouh, southwest of Isfahan, is one of the country's largest lead and zinc mines. During the years of activity, the mine produced a large amount of mineral deposits that contaminated the dirt surrounding the mine with potentially toxic elements. In order to investigate the effectiveness of the chemical washing method for remediation of contaminated soils from agricultural land around the mine, 36 specimens were harvested and a representative specimen was prepared. Also the sample of waste treated waste was harvested. After preparation of the samples, the total concentration of the elements was measured using the ICP-OES device. To characterize the sequential extraction analysis elements, soil reagents and reagents were used. The sequential extraction results showed that the highest amount of lead and zinc in the soil sample was located in the iron oxide-manganese and carbonate oxide section. In the waste sample, lead is mainly in carbonate, iron oxide, manganese and zinc oxide, often in carbonate. In order to investigate the effectiveness of the chemical washing method, several chemical agents (hydrochloric acid, nitric acid, potassium dihydrate, sodium acetate, acetic acid, sodium hydroxide and sodium-ethylenediaminetetraacetic acid) were first used. The results showed that Na2EDTA and NaOH have the highest and lowest yields for lead and zinc removal, respectively. The probable cause of this is the presence of high levels of lead and zinc in the oxide and carbonate portions of the soil and the ability to complete high-level complexation of lead and zinc with Na2EDTA. After selecting the appropriate material for extraction of lead and zinc, in order to achieve the highest removal rate, several parameters (particle size, pH, concentration, time, and liquid to solid ratio) were optimized. The results of the optimization show that the smaller the particle size, the greater the removal rate due to the high surface area and the high concentrations of fine particle size elements. The highest percentage of Pb and Zn removal was obtained at a pH of 63.2, a concentration of 0.05 M Na2EDTA and 120 minutes. The optimization of the solid to liquid ratio showed that this parameter had no significant effect on the removal rate. To remove lead and zinc from waste sampling, three inorganic acids (HNO3, HCl, H2SO4) were used in 4 concentrations (1, 0.5, 0.1, 0.05 M). The results show that HCl at 1 molar concentration and H2SO4 at the concentration of 0.05 mol, respectively, have the highest and lowest removal rates of lead and zinc, respectively.
Keywords:
#Potential toxic elements #Na2EDTA #Sequential extraction #Soil wahing method Link
Keeping place: Central Library of Shahrood University
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