Chromium Removal Using Soil Loaded with Green Iron Nanoparticles
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Chromium Removal Using Soil Loaded with Green Iron Nanoparticles Christiana Mystrioti1 · Thanasis Mpouras2 · Nymphodora Papassiopi1 · Dimitrios Dermatas2 Received: 1 April 2020 / Accepted: 13 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Chromate is considered as a serious environmental problem due its toxicity. Iron nanoparticles produced by green tea polyphenols (GT-nZVI) is a powerful reductant, which can effectively reduce Cr(VI) to Cr(III). Nano ZVI suspension was initially conceived ideal for direct injection in the contaminated aquifers. However GT-nZVI presents limited mobility in calcareous aquifers. For this reason the incorporation of nanoiron in a permeable reactive barrier was investigated as an alternative mode of GT-nZVI application. Namely an amount of soil was loaded with nZVI (0.40 mmol/g of soil) and was evaluated for Cr(VI) removal by conducting batch and column tests. Batch tests were carried out by mixing soil samples, loaded with different levels of nZVI from 0.04 to 0.40 mmol per gram, with contaminated groundwater (GW) containing 1300 ppb Cr(VI). Cr(VI) concentration dropped below detection limit within 1 day using the highest nZVI dose. Soil pre-loaded with nZVI (S-nZVI) presented also high efficiency for chromates remediation, when tested under flow conditions by conducting column tests. Keywords Hexavalent chromium · Soil loaded nZVI · Green nano-iron · Calcareous soils · Batch tests · Column tests · Permeable reactive barriers The groundwater and surface water contamination by organic and inorganic pollutants is considered as a major environmental issue. At Eastern Central Greece, high Cr(VI) concentrations have been detected in groundwater (Dermatas et al. 2015). Hexavalent chromium is ranked 119th in the EPA list of 126 Priority Pollutants (EPA Priority Pollutants List 2014) due to its toxicity and mutagenicity. Various technologies have been tested for hexavalent chromium removal, such as electrochemical remediation, chemical reduction, adsorption and membrane filtration (Dalal and Reddy 2019; Moharem et al. 2019). The removal of heavy metals using nanoparticles have been successfully tested the last years (O’Carroll et al. 2013). The elemental metals (Fe, Ag, Zn) in nanoscale are more effective compared to their granular forms due to the larger specific surface area and high reactivity. The efficient reduction of Cr(VI) to Cr(III) by green iron nanoparticles have been evaluated at laboratory tests and at pilot scale application (Mystrioti et al. 2016, 2018; Mpouras * Christiana Mystrioti [email protected] 1
School of Mining and Metallurgical Engineering, National Technical University of Athens, 15780 Athens, Greece
School of Civil Engineering, National Technical University of Athens, Athens, Greece
2
et al. 2014). However iron nanoparticles suspension present limited mobility to calcareous soils which are commonly encountered in the aquifers of Mediterranean countries. In this study an alternative mode of using nZVI was
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