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

Elemental sulfur (S-8) is an abundant and inexpensive by-product of petroleum refining. Polymeric sulfur is thermodynamically unstable and depolymerizes back to S-8 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 (Mx+ = 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 approximate to 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.