Optimization of elemental recovery from electronic wastes using a mild oxidizer
Chuchai Sronsri1, Wanpasuk Sittipol2, Napong Panitantum3
1Future Innovation & Research in Science and Technology, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
Waste Management (New York, N.Y.)
|October 7, 2021
Summary
Metals were recovered from electronic waste using optimized electrochemical and columnar extraction methods. This study achieved high recovery rates for industrial metals, gold, and rare-earth elements, minimizing waste generation.
Area of Science:
- Environmental Science
- Materials Science
- Chemical Engineering
Background:
- Electronic waste (e-waste) poses significant environmental challenges due to the presence of valuable and hazardous metals.
- Efficient and sustainable methods for metal recovery from e-waste are crucial for resource conservation and pollution reduction.
Purpose of the Study:
- To develop and optimize methods for recovering valuable metals, including industrial metals, gold, and rare-earth elements, from electronic waste.
- To enhance metal recovery efficiency and minimize waste generation through optimized extraction processes.
Main Methods:
- Columnar extraction was employed to improve contact between leachate and solid waste for industrial metal recovery.
- An electrochemical process with a regenerated oxidizer was optimized for metal concentration and waste reduction.
- Selective columnar extraction and adsorption processes were utilized for gold recovery.
- Acidic extraction under anaerobic conditions was performed for rare-earth element recovery, followed by precipitation and transformation.
Main Results:
- Maximum recovery rate of 1.135 mg·min⁻¹ for industrial metals achieved at 160 A·m⁻² current density, 7 mL·min⁻¹ flow rate, and 0.8 mol·L⁻¹ ferric concentration.
- Highest gold extraction efficiency of 69.39% obtained using 0.7 mol·L⁻¹ thiourea, 0.6 mol·L⁻¹ hydrochloric acid, 0.8 mol·L⁻¹ ferric chloride, 120 min circulation, and 6 mL·min⁻¹ flow rate.
- Adsorption of gold followed the Langmuir model and first-order kinetics, with optimal conditions identified.
- Recovery efficiencies for cerium and neodymium reached 91.7% and 86.7%, respectively.
Conclusions:
- Optimized electrochemical and columnar extraction techniques significantly enhance metal recovery from e-waste.
- The developed methods are effective for selectively recovering gold and rare-earth elements, contributing to sustainable resource management.
- This research provides a framework for efficient metal reclamation from electronic waste, reducing environmental impact.
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