CHENNAI: Researchers at the Indian Institute of Technology Madras (IIT-M) have developed a green, non-toxic and water-efficient technology to recover valuable metals from electronic waste, offering a cleaner alternative to conventional recycling methods that rely on hazardous chemicals.
The innovation, based on environmentally benign solvents derived from natural compounds, could significantly strengthen India's circular economy efforts while reducing the environmental damage caused by the rapidly growing e-waste stream.
Electronic waste contains high concentrations of recoverable metals such as copper, gold and iron, but existing extraction techniques typically use strong acids, generating toxic effluents and impure metal outputs. To address this, the IIT-M team turned to deep eutectic solvents (DES), biodegradable liquid mixtures capable of dissolving metals without environmental harm.
A green solvent using thymol, derived from thyme, and capric acid formulated by the researchers efficiently dissolved copper, which was then extracted using trisodium citrate, a non-toxic reagent, and converted into copper nanoparticles with wide industrial applications. By fine-tuning the pH, the process yielded copper oxide nanoparticles or pure copper metal.
The method was also successfully extended to recover iron from real e-waste samples, including printed circuit boards.
The research was carried out by Professor Ranjit Bauri of the Department of Metallurgical and Materials Engineering, Professor S Pushpavanam of the Department of Chemical Engineering, and Sinu Kurian, a doctoral researcher jointly affiliated with both departments.
The findings were published in The Journal of Sustainable Metallurgy.
"Unlike acid-based extraction, this process is biodegradable, non-toxic and generates no hazardous waste. It can recover multiple metals and directly produce value-added nanomaterials," Pushpavanam said.
Ranjit Bauri noted that the technology could reduce pollution from e-waste recycling and cut dependence on virgin metal mining, aligning with India's sustainability and net-zero goals.
Sinu Kurian said the process has been validated at the laboratory scale and the next phase will focus on industrial scaling, solvent recyclability and cost optimisation. IIT-M is exploring industry partnerships for pilot-scale deployment and technology transfer.