Process optimization and mechanism for the selective extraction of copper(ii) from polymetallic acidic solutions using a polymer inclusion membrane (PIM) with Mextral®5640H as the carrier

Abstract

This study introduces a novel approach by integrating solvent extraction and polymer inclusion membrane (PIM) separation technologies to engineer an innovative PIM membrane material for the selective separation and enrichment of strategic metals, particularly copper, from polymetallic acidic solutions. The primary objectives were to streamline the technological process, reduce production costs, and enhance separation coefficients between copper and other metals. The optimal extraction conditions were determined as a mass fraction of Mextral®5640H : PVC : NPOE = 3 : 3 : 4, extraction temperature of 35 °C, and 0.9 mol L⁻¹ H₂SO₄ in the stripping solution. Under these conditions, we achieved remarkable extraction efficiencies, with copper reaching 100%, and the separation coefficients between Cu²⁺ and Ni²⁺, Co²⁺, and Zn²⁺ exceeding 10⁶. To elucidate the substantial differences in extraction performance between Cu²⁺ and the other metals (Ni²⁺, Co²⁺, and Zn²⁺), we employed an integrative analytical approach that combines FT-IR spectroscopy, BET analysis, and theoretical calculations. All extracted complexes demonstrated molecular sizes compatible with PIMs, underscoring the critical role of stability and back-extraction performance in the selective extraction of these metal ions.