Application of Partially Miscible Solvent System for an Efficient Extraction of Organic Pollutants from Contaminated Sludge
. Water, Air, and Soil Pollution 2019
. Publisher's VersionAbstract
A systematic study of extraction of various organic pollutants from highly contaminated solid media (e.g., sludge) by applying a phase transition of a benign partially miscible solvent system composed of water/ethyl acetate/ethanol was conducted. This solvent system possesses an upper critical solution temperature of about 55 °C. The efficiency of the phase transition extraction (PTE) process is found to be higher and much faster compared to those obtained without phase transition (at ambient temperature). The influence of various operating conditions on the process efficiency was investigated. The performance of the phase transition extraction when applied on contaminated sludge is much better than the extraction with ethyl acetate only, although the latter is shown to be a very efficient solvent for extracting various organic contaminants (e.g., pharmaceuticals, persistent organic pollutants) from aqueous solutions. The efficiency of phase transition extraction from the aqueous solution was somewhat lower than that achieved with ethyl acetate, but it shows a clear advantage in the presence of detergents, as emulsion formation is prevented. © 2019, Springer Nature Switzerland AG.
New insights into chelator recycling by a chelating resin: From molecular mechanisms to applicability
. Chemosphere 2019
, 800-806. Publisher's VersionAbstract
As part of the project of developing a “green” and highly feasible soil remediation process, recycling an eco-friendly chelating agent, glycine, using Chelex-100 chelating resin, was studied. Two model complexes, copper and nickel glycinates, were tested under various conditions, including equivalent viscosity but different temperature conditions. Two similar complexes demonstrated very different reactivity towards Chelex-100. An in-depth study led to the discovery of unusual metal-dependent mechanisms of the complex-to-resin metal transfer. Particularly, nickel transfer proceeds via a dissociative mechanism, whereas copper transfer does not require pre-dissociation of the complexes, and proceeds via the associative ligand-exchange mechanism. Both processes result in the recovery of the used chelator. The glycine solution was applied on the spiked soil, then recovered on Chelex-100 resin and successfully reused, thus demonstrating a proof of the concept. These findings contribute to the science, strategies, and methodology of both water purification and chelator recycling fields. © 2018 Elsevier Ltd