Controlled synthesis of Fe₃O₄/MnO₂ (3 1 0)/ZIF-67 composite with enhanced synergetic effects for the highly selective and efficient adsorption of Cu (II) from simulated copperplating effluents

This study designed a composite material with internal synergistic effects among multiple components to achieve highly selective adsorption of Cu (II). Through controlled synthesis, the Fe₃O₄/MnO₂(3 1 0)/ZIF-67 composite was successfully fabricated, leading to significant improvement in adsorption selectivity, capacity, and adsorption rate. The experimental results showed that the composite is of outstanding selectivity in the adsorption of Cu (II), with a partition coefficient K of Cu (II) that was 2.2–5.3 times higher than that of other coexisting ions. Moreover, the composite exhibited a remarkable adsorption capacity of 1261.0 mg g⁻¹ and a fast adsorption rate of 840.7 mg g⁻¹ h⁻¹ at 298 K. Additionally, its magnetic property facilitated easy separation from wastewater, thereby enhancing its potential for commercial applications. The synergetic effect mechanism was analyzed through characterizations and DFT calculations. Furthermore, the recyclability of the composite was investigated, which showed that after seven cycles, the adsorption efficiency remained at 85% of its initial efficiency. It can be concluded that Fe₃O₄/MnO₂(3 1 0)/ZIF-67 has potential to address challenges posed by heavy metal pollution in copperplating effluents.