Development of selective sorbents for the recovery of transition metal ions from battery waste through capacitive deionization

Abstract

In this study, amines and acid chloride were reacted through a room temperature method, and amines, carboxylic acids, and aldehydes reacted through a solvothermal method to produce seven different covalent organic frameworks in recovering transition metals from spent battery waste through capacitive deionization. The produced covalent organic frameworks were characterized by structural analyses, including BET surface area measurement, SEM analysis, FTIR spectroscopy, and XRD analysis, contact angle measurements to examine surface and porous structure, and surface morphology, determine which functional groups are present in the structure, and crystalline nature, and check hydrophilicity. A hybrid capacitive deionization technique was further employed to evaluate the capacitive behavior of the covalent organic frameworks as cathode electrode in capacitive deionization applications. The maximum metal uptake (10.13 mg/g cobalt, 24.43 mg/g nickel, 40.10 mg/g manganese and 4.70 mg/g lithium) and rate at 2 V were obtained using a covalent organic framework produced by reacting amines, carboxylic acids, and aldehyde by the solvothermal method, which resulted in both amide and imine linkages, along with nitrile functional groups retained from the nitrile-substituted amine precursors. The application of these covalent organic frameworks in capacitive deionization with battery leachates showed effective removal and recovery of transition metal ions, thereby contributing to waste valorization, offering low energy and environmentally friendly alternative to conventional recycling processes.