A chemo-geotechnical approach to obtain optimal mixtures of zeolite-bentonite as heavy metal adsorbents
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ORIGINAL PAPER
A chemo-geotechnical approach to obtain optimal mixtures of zeolite-bentonite as heavy metal adsorbents Elahe Karimdad 1 & Mohammad Bashirgonbadi 1 & Ebrahim Rahimi 1 Received: 4 January 2020 / Accepted: 26 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The removal or reduction of heavy metal leakage from waste leachates into the soil and aquatic environment has been of interest for many years. A suitable solution is to enclose wastes in the impermeable, adsorbent, and durable layers that tolerate different ambient conditions. This indicates the need to consider geotechnical parameters along with the adsorption behavior of the adsorbents. In routine practice, a mixture of bentonite clay, zeolite, and geo-synthetics is used. This study aims to introduce suitable mixtures of zeolite and bentonite as natural adsorbents for sealing/adsorption of heavy metals in liner systems. Various mixtures of bentonite and zeolites of clinoptilolite and clinoptilolite-heulandite types were examined. Twenty-three mixed and non-mixed samples were prepared and tested. Once the soil index and soil compaction parameters were determined, an experiment program was designed to evaluate the cracking potential related to the freeze-drying process, as well as the adsorption potential of the samples at different ambient conditions (i.e., temperature and pH). It is observed that increasing the temperature up to 40 °C increases the adsorption potential. According to the results, the optimal adsorbents were found in the mixtures of zeolite/bentonite with the ratio of 4:1 in the first place and zeolite/bentonite with a ratio of 3:1 in the second, under various conditions. Keywords Zeolite-bentonite mixture . Heavy metal adsorption . Chemo-geotechnical approach . Liner systems
Introduction The evaluation of the standards for designing landfill lining and capping systems legislated in different countries shows that low permeability is one of the most important criteria to prevent advective and diffusive transport through the systems (Chai and Miura 2002; Müller and Wöhlecke 2019). Heavy metals would enter the environment through natural phenomena and anthropogenic activities related to agriculture, mining, transportation, landfilling, metal finishing, tannery, electroplating, chemical manufacturing, battery production, and any other industrial manufacturing (e.g., Bashi-Azghadi et al. 2016; Bolan et al. 2014; Elhatip et al. 2004; Li et al. * Ebrahim Rahimi [email protected] Elahe Karimdad [email protected] Mohammad Bashirgonbadi [email protected] 1
School of Earth Sciences, Damghan University, Damghan 3671641167, Iran
2019). Living organisms need very small amounts of heavy metals known as trace elements, including iron, cobalt, copper, magnesium, molybdenum, vanadium, strontium, and zinc, to continue to grow and survive. A high concentration of these toxic elements in the environment affects the lives of humans, animals, and plants, and their growth will be interrupted. Heavy metal
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