Article ID Journal Published Year Pages File Type
6969846 Journal of Hazardous Materials 2016 6 Pages PDF
Abstract
The objective of this work is to evaluate the selectivity and solubility of a buffer chelant. The buffer chelant is ethylenediamine-nitrilotriacetic acid (NTA·3EDA) and its performance is compared to NTA. All experiments were conducted on batches of 25 g of soil in an autoclave at 25 °C or 75 °C with a constant L:S ratio of 2. The experiments were conducted under a CO2 overhead to lower the reaction pH. The buffer chelant allows a 5-fold selectivity increase for heavy metals while increasing or maintaining the same molar extraction yield compared to NTA. These selectivity and extraction results stand out from those obtained with other neutralized NTA. NTA, EDA and the acid gas CO2 are the three necessary ligands in the NTA·3EDA extraction mechanism. A reaction temperature setpoint increase causes a higher Fe dissolution. However, this does not lower the NTA and NTA·3EDA selectivity for heavy metals. Thus, Fe is a non-interfering cation in the NTA and NTA·3EDA extraction mechanisms. This non-interference is less apparent in the NTA extraction mechanism. The present work intends to share another perspective on the design of more selective and soluble chelants for heavy metal extraction.
Related Topics
Physical Sciences and Engineering Chemical Engineering Chemical Health and Safety
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