Impact of Enhancement on Heavy Metal Retention in Cement Based Solidified Contaminated Bentonite

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Impact of Enhancement on Heavy Metal Retention in Cement Based Solidified Contaminated Bentonite

ارائه دهنده: Provider: shirin darvishpour

اساتید راهنما: Supervisors: Dr. Vahidreza Ouhadi

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Masoud Makarchian, Dr. Abbas Ghadimi

زمان و تاریخ ارائه: Time and date of presentation: 2022 - Tuesday, March 15 from 10 to 12

مکان ارائه: Place of presentation: virtual

چکیده: Abstract: Heavy metal soils are one of the most common problems worldwide. Accumulation of risk is unavoidable not only because of world population growth, but also because of the rapid expansion of the industrial, economic and agricultural sectors. Due to the use of industrial landfills, pesticides, chemical fertilizers, emissions from municipal incinerators, car exhaust, metal ore production, and metal smelting industries, heavy metals may be present. (HMs) from zinc (Zn), cadmium (Cd), lead (Pb) and copper (Cu) contaminants. Identification and burial of heavy metal contaminated products in groundwater and groundwater. Due to the degradability of heavy metals and their toxicity to biological systems, this category of consumption has always been considered from an environmental point of view. Stabilization / Solidification (S / S) has been a common method of hazardous treatments in the past and has been used for decades to bury radioactive waste and hazardous items. Stabilization / Solids Reacting using chemicals is a way to create stable solids that are safe or less hazardous than raw materials. Solidification of contaminants refers to changes in the material in the contaminant that is attached to a substance. These changes include increasing compressive strength, decreasing permeability and compaction of hazardous materials. Contaminant fixation refers to chemical changes between the fixing agent (binding agent) and the hazardous ingredients. Many stabilization / solidification (S / S) based soil clearing technologies are a mixture of mineral compounds (cement, lime, sodium silicate, clay, clay, clay, clay, fly ash, kiln coal, kiln dust, etc.) Repair soils contaminated with organic and inorganic contaminants. Alkalis are added to these mixtures to enhance the stabilizing properties of the refined soils, especially in relation to heavy metals. There are various methods for remediation of contaminated soil, which generally include methods based on the extraction and separation of contaminants from the soil or methods based on solidification of contaminants in the soil. US Environmental Protection Agency (USEPA); Solidification by the cementation process has been described as "the best proven existing technology" for burying more and better toxic elements in nature. The use of cement increases energy consumption and increases CO2 emissions. Approximately 5% of global CO2 is produced by the cement industry. By promoting sustainable development, due to similar methods of green development with engineering properties or even better than cement, among the mixed compounds used in many S / S techniques, fly ash and zeolite due to their cheapness and specificity . Its very good pozzolanic has been used as a substitute for cement. In general, the purpose of this study is to use fly ash and zeolite in agricultural engineering landfill projects in order to prevent the spread and transfer of heavy metal pollutants and save cement consumption in solidification projects using fly ash and zeolite. The group of materials with less financial value. Wind ash and zeolite in the form of 10 to 50% by weight of soil, added to contaminated bentonite with 10, 50, 100 and 150. After storing the samples for 7 and 28 days, the stabilization / solidification samples of the studies performed in both macro-structural and microstructural sections were evaluated. First, the study of the hydration reactions of cement and the formation of pozzolanic reactions caused by fly ash and zeolite over time has been studied. The results show that in samples with 50% zeolite binder, pozzolanic reactions are faster than other samples and the final setting time of these samples is shorter. In the second part, the behavior of lead and fly ash and zeolite with different layers of lead pollutants and different structures in the absorption and storage of heavy metals is investigated. The contaminant is lead. In the next section, the protection of lead contaminants is examined by TCLP testing. Based on the results of adding fly ash and zeolite in different binders, the effect of the stabilization variable and increasing the pH range compared to the intensification samples in the TCLP experiment was not performed. So pH is an important factor in the TCLP test. The results show that different 10% cement additives, with common recommendations in geotechnical stabilization, are not suitable for stabilization / solidification of contaminated bentonite soil in all studied Pb nutrients. Finally, the samples are analyzed by performing an X-ray jump (XRD) test, which can be used for the results of other tests

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