Washing and Extraction of Metals from Contaminated Soil Constituents: Implications for Contaminated Simulated Soil and Metallurgical Wastes with Different Reagents

Abstract

Leaching behaviour of heavy metals (HMs) from simulated soil (SS), prepared according to standard guidelines, as well as its constituents (quartz sand (QS), bentonite clay (BC), and peat moss (PM)) were investigated. The study focused on a batch process with the aim of comparing the leaching potentials and metals solubilisation of ethylene diamine tetraacetic acid (EDTA), ethylene diamine disuccinic acid (EDDS), acetylacetone (Hacac), citric acid (CA), and tartaric acid (TA) for sustainable metal extraction purposes after a maximum leaching time of 60 min. The HMs concentrations with which the constituents were spiked with was such that reflected a contaminated site. The recovery potentials of both the SS and its constituents were found to vary for single metal (SM) and multi-metal (MM) systems. EDTA was the most efficient (on average 31% and 33% for SM and MM) and TA the least efficient (on average of 2% and 3% for SM and MM) extractant. For Hacac, preferential recovery for Cu and Ni were significant when compared to the other metals, while, metal recovery by EDDS in SS was lower than could be expected. The leaching trend for the targeted metals was studied using conventional leaching models.