The utilization of zinc recovered from alkaline battery waste as metal precursor in the synthesis of metal-organic framework

In the treatment of spent wastes, seeking extra economic incentives (e.g., through their regeneration into value-added end products) along with environmental protection is a highly ideal option to consider. In this context, a process was developed to utilize spent alkaline battery waste as a source medium of zinc (Zn²⁺) ions for the synthesis of a high-value material, metal organic frameworks (MOFs). For this purpose, multiple options including acid leaching and base precipitation were first compared for separation of Zn²⁺ ions from battery waste. Secondly, MOF-5 synthesis was carried out through two different routes: one using the Zn²⁺ ions separated from waste batteries (W-MOF-5) and the other using pure chemicals (P-MOF-5). Finally, differences in the structural properties (e.g., crystallinity and morphology) between the two MOF-5 types were assessed through characterization experiments (e.g., FTIR, PXRD, and SEM analyses) and modeling (DFT) studies. W-MOF-5 was found to possess tetragonal lattice parameters which indicated decrease in the Zn²⁺ ions in the framework. This deficiency increased the interplanar Bragg angles which led to the different size and shape of W-MOF-5. Also, the PXRD spectrum indicated the presence of all peaks at similar position with that of P-MOF-5. Additionally, the preparation of 1 kg of W-MOF-5 requires a low cost (42 USD) when one considers >90% of solvent recovery. Also in terms of materials cost, the synthesis of W-MOF-5 was highly cost-effective than that of ZnO nanoparticles. In light of many compatibilities between MOFs synthesized through the two different routes, the method proposed in this work can be further developed toward a simple, fast, and reliable route for MOF-5 production from battery waste.