چكيده فارسي :
زمينه و هدف: خاك‌هاي آلوده به فلزات سنگين يكي از مشكلات متداول ژئوتكنيك زيست‌محيطي در سراسر جهان هستند. از سوي ديگر ايجاد بستري مناسب براي مراكز دفن زباله همواره يكي از مخاطرات پژوهشگران ژئوتكنيك و ژئوتكنيك زيست‌محيطي در سه دهه گذشته بوده است. ارائه ماده‌اي با خصوصيات ژئوتكنيك زيست‌محيطي مناسب با كمترين ميزان نفوذپذيري و قابليت جذب حداكثري آلاينده از اهداف اين مقاله است. فرايند توليد نانوذرات رسي از رس‌هاي بنتونيت با رويكرد بالا به پايين شامل حذف بعضي از مواد به شكل ضايعات است. در پژوهش‌هاي صورت گرفته از طريق فرايندهاي فيزيكي و شيميايي اجزاي نمونه رسي بنتونيت به دو بخش اصلي نانومونت‌موريلونيت (SLB) و ضايعات فرايند (BLB) جداسازي شده است. روش بررسي: در اين پژوهش با انجام يك سري آزمايش‌هاي ژئوتكنيكي و ژئوتكنيك زيست‌محيطي فرايند اندركنش نانومونت‌موريلونيت (SLB)، ضايعات فرايند (BLB) و نمونه رسي بنتونيت با آلاينده‌هاي فلز سنگين مورد مطالعه و تجزيه و تحليل آزمايشگاهي قرار گرفته است. شايان ذكر است روند جداسازي اجزا نمونه رسي بنتونيت از طريق آزمايش‌هاي ريزساختاري پراش اشعه ايكس (XRD)، تعيين سطح ويژه (SSA) و بررسي تصاوير ميكروسكوپ الكتروني پويشي (SEM) مورد آناليز قرار گرفت. بحث و نتيجه‌گيري: نتايج تحقيق حاضر نشان مي‌دهد، ضايعات فرايند (BLB) حدود 80% آلاينده فلز سنگين مس را در غلظت cmol/kg-soil 100 نگهداري مي‌كند. همچنين ميزان نفوذپذيري نمونه BLB در حدود m/sec 10-10*5.2 و درصد تورم آن 70% است
چكيده لاتين :
Soils contaminated with heavy metals are among the common environmental geotectonic problems all around the globe. Clay is considered as one of the best protective layers for environment to absorb polluters. Considerable SSA, very low permeability and the clays cationic capacity have been good factors to use these materials in geo-environmental projects vastly. It can react with the materials existing in the polluters because of the layered structure and special vast surface so the clay can absorb all or some of the dangerous polluter materials passing through the soil. Each part of the mineral materials constituting the clay, carbonate, organic materials, oxides, amorphous materials or remained phases can play a role in the process retention heavy metals. Carbonates play a special role in the process of the clay and metallic polluters’ interaction. The effect of the soil structure in retention heavy metal has been studied in many researches. In geotechnical environment view the clay mineral montmorillonite is one of the clays used in geo-environmental projects. Among the clay minerals montmorillonite has the highest property absorbing polluters. In the absence of clayey soils, compacted bentonite-enhanced sand mixtures are attracting greater attention as suitable material for contaminant barrier systems. The efficiency of these insulated barriers depends largely on their hydraulic and mechanical behavior. In landfills, as the main function of the liner is to minimize the movement of water out of the waste disposal facility, Landfill should satisfy three performance criteria if it is to perform satisfactorily as a barrier material. It should have low hydraulic conductivity (typically less than 1×10-9 m/s), should have sufficient strength in order to be stable during construction and operation, and it should not be susceptible to excessive shrinkage cracking due to water content changes that usually occur during the lifetime of the landfill. On the other hand, provision of the proper platform for landfills has been a concern of geotectonic and environmental geotectonic researchers in the past three decades. One of the objectives of this research was to introduce a material with suitable environmental geotectonic properties, minimum permeability, and maximum contaminant absorption potential. The process of producing nanoclay particles from bentonite clay with a top-down approach involves omission of some materials in the form of tailings. In related studies, the bentonite clay sample was divided into the following two main parts through physical and chemical processes: nano-montmorillonite (SLB) and process tailings (BLB). In this research, through a series of geotectonic and environmental geotectonic experiments the interaction of nano-montmorillonite interaction (SLB), process tailings (BLB), and bentonite clay samples with heavy metal contaminants was studied and analyzed experimentally. It shall be mentioned that the process of separating bentonite clay sample components was analyzed through microstructural X-ray diffraction (XRD) and specific surface area (SSA) experiments as well as scanning electron microscope (SEM) imaging. The tests conducted in the study were mostly on the basis of ASTM standard and the geo-environmental tests directions issued by McGill University of Canada. The soil carbonate percentage was defined by titration method. The specific surface area (SSA) was determined using the ethylene glycol-monoethyl ether (EGME) method. CEC was determined by the BaCl2 replacement method. The carbonate content of the soil was determined by titration, and the soil pH was measured in 1:10 soil solution.Also the soil pollution retention capacity was measured by titration test and HNO3 in different concentrations was added to the samples. Results of the present research suggest that process tailings (BLB) contain approximately 80% of copper as a heavy metal contaminant at a concentration of 100 cmol/kg-soil. In addition, permeability of the BLB sample and its inflation are approximately 5.2 10-10 m/sec and 70%, respectively.
