Recovery of cobalt from spent lithium ion batteries utilizing surface modified graphene oxide

Abstract

Metal content present in the spent lithium ion batteries (LIBs) make their recycling vital for resources conservation and environmental sustainability. Cobalt, grouped among critical, valuable and strategic metals, is the basic part of the LIBs cathode and defines its recycling economic capacity. In the present work, an attempt has been made to develop an efficient hydrometallurgical technique based on solid phase extraction method for the recovery of cobalt from leach solution of waste LIBs. An adsorbent was synthesized by diazotization of p-phenylenediamine modified graphene oxide (GO-PPDA) sheets with disodium 1-nitroso-2-naphthol-3-6-disulphonate (nitroso R-salt, NRS) in one pot process of Mill's reaction. Maximum retention of cobalt (99.9%) was achieved at pH 5.5–6.5. Adsorption kinetics favour complexation as a separation mechanism following second order kinetics model with R2 value of 0.9999 with sample flow rate of 1.5 mL/min. Langmuir isothermal model (R2 = 0.998) also confirm monolayer chemisorption mechanism with 29.7 mg/g adsorption capacity. The two-step elution mechanism enables us to achieve 99.5% extraction efficiency with ~98% purity. The chelating adsorbent was found reasonably stable even after the 30th cycle of adsorption and desorption with <2% decrease in removal efficiency. The results show that the proposed adsorbent is successful in terms of selectivity, reusability, analytical merit and stability.