Efficient and sustainable recycling for waste gallium arsenide semiconductors based on triiodide ionic liquids

Abstract

Gallium arsenide semiconductors (GaAs), holding immense value, can cause environmental pollution and resource waste if stacked up or landfilled at will. Nevertheless, current research on GaAs recycling faces challenges of elevated energy demands and environmental repercussions. Consequently, we developed an efficient and sustainable GaAs recycling technology with promising potential. By utilizing synthesized triiodide ionic liquids, we selectively leach As and Ga from discarded GaAs without relying on strong acids, alkalis, or hazardous cyanide, and no generation of harmful byproducts, thereby reducing environmental impacts. This method achieves exceptional recovery efficiency (As: 94.1%, Ga: 97.1%), high purity (As: 99.9%, Ga:99.7%), and remarkable reusability (over 6 cycles). Our findings revealed that the successful leaching of As and Ga was attributed to powerful redox and complexation mechanisms. In-depth exploration of leaching kinetics indicated that the reaction occurred at intermediate layer and unreacted core, following mixed control model. Notably, this method is ideal for real-world application given the low-energy (80oC), low-viscosity (below 35 cP) and one-step leaching and recovery. Importantly, life cycle assessments indicate that this recycling method substantially mitigates various environmental pressures. And the economic analysis showed that recovering 1.0 kg of waste GaAs could yield a significant profit of 3.36×104 USD. Overall, this innovative strategy represents a noteworthy advancement in green recycling technology.