# Sustainable Recovery of Cu, Fe, Ni, and Zn from Multilayer Ceramic Capacitors Using a Ternary Deep Eutectic Solvent

## TL;DR

This paper presents a sustainable method using deep eutectic solvents to recover valuable metals like copper, nickel, and zinc from electronic waste.

## Contribution

The study introduces a ternary deep eutectic solvent (GLY-CA) for efficient and eco-friendly metal recovery from multilayer ceramic capacitors.

## Key findings

- Copper and zinc were fully recovered using citric acid and the GLY-CA mixture.
- The ternary solvent (GLY-CA) showed lower viscosity, improving handling and efficiency.
- Iron recovery reached a maximum of 60%, likely due to its varied chemical forms.

## Abstract

The rapid growth in electronic waste (e-waste) generation highlights the urgent need for efficient and environmentally sustainable methods for metal recovery. This study focuses on the selective recovery of valuable metals from multilayer ceramic capacitors (MLCCs), commonly found in printed circuit boards (PCBs) of post-consumer electronics. MLCCs were manually recovered from dismantled computer PCBs, thermally treated, pulverized, and characterized using X-ray fluorescence and X-ray diffraction techniques. To evaluate green alternatives to traditional acid leaching, three deep eutectic solvents (DESs) based on choline chloride (ChCl) were prepared: citric acid (CA), glycerol (GLY), and a ternary (GLY-CA) mixture of both (GLY-CA). Leaching experiments were conducted over a 24 h period and analyzed using atomic absorption spectroscopy. The results showed complete recovery (100%) of copper using both CA and the GLY-CA mixture, while nickel recovery reached 100% with CA and moderate levels with GLY-CA. Zinc recovery was also high (99%) with both CA and GLY-CA. Iron showed a maximum recovery of 60%, potentially due to its occurrence in various chemical forms. The ternary DES (GLY-CA) demonstrated lower viscosity, improving handling and operational efficiency. These findings highlight the potential of citric-acid-based and ternary (GLY-CA) DESs as effective, low-toxicity leaching agents for the recovery of critical metals from MLCCs.