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

Abstract

Gallium arsenide (GaAs) semiconductors, 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 leached As and Ga from discarded GaAs without relying on strong acids, alkalis, or hazardous cyanide, and there was no generation of harmful byproducts, thereby reducing environmental impact. 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 an intermediate layer and unreacted core, following a mixed control model. Notably, this method is ideal for real-world application given the low-energy (80 °C), 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 an 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.