An eco-friendly approach for metals extraction using polymeric nanofibers modified with di-(2-ethylhexyl) phosphoric acid (DEHPA)

The aim of this work was to develop new materials employing polymeric nanofibers modified with an organic extractant for the extraction of metals. For this purpose, nylon-6 nanofibers were modified with di-(2-ethylhexyl) phosphoric acid (DEHPA) for use in the selective extraction of zinc and nickel. The best extraction efficiencies were 85.5% for Zn and 4.6% for Ni, achieved under the following conditions: pH 2, solid:liquid (S:L) ratio of 1:40, and contact time of 7.5 min. In the stripping, the best efficiencies were 85.9% for Zn and 90.1% for Ni, using a concentration of HCl of 0.5 M, S:L ratio of 1:10, and contact time of 5 min. The nanofibers were evaluated in terms of their stability and capacity for reuse, and it was found that there was no loss of the DEHPA extractant from the nanofibers, while the extraction efficiency remained almost constant. Regarding to environmental aspects of the new technology, the results confirm that nanofibers exhibit the same efficiency of conventional liquid-liquid extraction, without the disadvantage of the use of organic solvents. In this way, this new technology brings an enormous gain in environmental terms, since it drastically reduces the use of hazardous substances. (C) 2018 Elsevier Ltd. All rights reserved.