Indian Institute of Technology Madras (IIT Madras) Researchers have developed an innovative, green, and sustainable method to recover valuable metals from electronic waste (e-waste) using environmentally-friendly solvents derived from natural compounds.

This breakthrough could pave the way for safer and more eco-efficient e-waste recycling practices that protect the environment while supporting India’s circular economy goals.

Video Bytes of the researchers explaining this work can be viewed and downloaded from the following link - https://drive.google.com/drive/folders/1GBnK52N9RR2HaqxIBcS3v52CRLpLPA0N?usp=sharing

E-waste, one of the fastest-growing waste streams globally, contains a wealth of recoverable metals such as copper, gold, and iron. Yet, conventional recycling methods rely on harsh chemicals that produce toxic effluents and often yield metals in impure forms requiring further processing.

To overcome these challenges, the IIT Madras research team explored the use of deep eutectic solvents (DES) — special liquid mixtures made from biodegradable natural substances that can dissolve metals without harming the environment.

In their study, the team developed a green solvent from thymol (derived from thyme) and capric acid, which effectively dissolved copper metal. The dissolved copper was then safely extracted using trisodium citrate, a non-toxic chemical, and subsequently used to synthesise copper nanoparticles — materials with significant industrial and technological applications.

By adjusting the pH of the solution, the researchers could produce different forms of copper, such as copper oxide nanoparticles and pure copper metal. The process was also successfully extended to recover iron from real e-waste samples like printed circuit boards and copper sheets.

The research was conducted by Prof. Ranjit Bauri, Department of Metallurgical and Materials Engineering; Prof. S. Pushpavanam, Department of Chemical Engineering; and Ms. Sinu Kurian, Ph.D. Research Scholar jointly affiliated with both the departments.

The findings were published in The Journal of Sustainable Metallurgy (https://doi.org/10.1007/s40831-025-01204-1), a reputed peer-reviewed journal that focuses on advancing the circular economy principle

Elaborating on the unique aspects of this Research, Prof. S. Pushpavanam, Department of Chemical Engineering, IIT Madras, said, “Unlike conventional acid-based extraction techniques, this method is biodegradable, non-toxic, and water-efficient, generating no hazardous waste. Its ability to recover multiple metals and directly produce valuable nanomaterials makes it more versatile and sustainable than other existing approaches.”

Further, Prof. Ranjit Bauri, Department of Metallurgical and Materials Engineering, IIT Madras, said, “This green recovery process can significantly reduce pollution and environmental damage caused by e-waste while minimizing the demand for virgin metal mining. For society, the innovation promises safer recycling systems, cleaner ecosystems, and efficient use of natural resources, aligning with India’s sustainability and net-zero commitments.”

Speaking about the current status of the research, Ms. Sinu Kurian, Ph.D. Research Scholar, added, “Currently, our research has shown successful laboratory-scale results, validating its potential across multiple metals and real e-waste samples. The next phase will focus on scaling up the process for industrial applications, improving solvent recyclability, and testing cost-effective alternatives to enhance economic viability.”

IIT Madras is also exploring collaborations with industry and recycling companies for pilot-scale implementation, with possibilities of technology transfer and licensing to enable real-world adoption.