Recovery of toxic metal ions from washing effluent containing excess aminopolycarboxylate chelant in solution

Abstract

Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatment of toxic metal-contaminated solid waste materials.Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated

Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation

“…A careful cleaning of the laboratory wares was ensured following the process described by Hasegawa et al [25] before and after each use.…”

“…The next step was the washing with the ultrapure water followed by elution (1 and 6 mol L -1 HNO 3 + ultrapure water). More detail about the adopted separation arrangement, including the optimization of the aforementioned steps is described elsewhere [25].…”

“…Hence, the metal-extraction process that includes the use of chelant should have the option for recycling of the chelant for concurrent application after the recovery of metal to reduce the cumulative cost-factor [25,33,34]. It was observed that the temperature within the reaction system is better to be maintained ~120 °C for considerable removal of indium from the waste source without the eradication of the chelant and is, therefore, practiced.…”

“…A MRT-SPE, AnaLig TE-01, showed better separation efficiency than the chelating resins and the ion-exchange resins for the separation of toxic metal ions from the washing effluent containing APCs [25]. In the current work, four other MRT-SPE options (TE 06, TE 07, TE 09 and TE 13) from the AnaLig TE-series, including the AnaLig TE-01, have been evaluated for the separation of indium from chelant solution.…”

“…9) matrix based on the combination of size, configuration, electronic interaction, charge, wetting, and other factors [46]. The proposed separation scheme with the use of MRT-SPE has the subsequent advantage of recycle the chelant [25]. However, the ITO-thin film in the LCDwaste also contains tin as an ingredient, and the chelant-induced co-extraction of tin was likely with indium according to its corresponding ratio in the ITO.…”