Sulfur–oleylamine copolymer synthesized via inverse vulcanization for the selective recovery of copper from lithium-ion battery E-waste

Abstract

Elemental sulfur (S₈) is an abundant and inexpensive by-product of petroleum refining. Polymeric sulfur is thermodynamically unstable and depolymerizes back to S₈ with time, which limits its applications and causes megatons of sulfur to accumulate in nature. A novel sulfur–oleylamine copolymer, synthesized using the inverse vulcanization method, is reported for the selective recovery of Cu²⁺ from a complex mixture of transition metals. Adsorption studies have been performed using batch experiments in the simulated aqueous solution containing a mix of metal ions (M^x+ = Fe, Al, Mn, Co, Ni and Cu). The effect of different adsorption parameters such as pH, time, adsorbent dose, sulfur content, and desorption have been studied. The results demonstrate that the sulfur–oleylamine copolymer shows high selectivity towards Cu²⁺, with excellent adsorption efficiency of >98% in acidic pH (pH ≈ 1) at room temperature, which is of practical relevance in the handling of battery leach liquors obtained from industrially derived blackmass. Finally, the sulfur–oleylamine copolymers were also applied to battery leach liquors with hydrochloric (HCl) or citric acid and showed Cu²⁺ adsorption efficiency of >98% ± 1 and > 95% ± 7, respectively. This work presents a novel way to convert industrial waste into a stable sulfur polymer and demonstrates its use as a promising material for selective recovery of Cu ions from battery waste and industrial effluents in a simple and cost-effective manner.