Iranian Scientists Find New Method to Turn E-Waste into Gold
Amin Zadeh Nazari, a senior researcher and postdoctoral scientist in the laboratory of Professor Alireza Abbas Pour Raad at Cornell University, said that given that approximately 50 million tons of e-waste are produced annually and only 20 percent of it is recycled, this approach could help reduce the environmental burden.
Zadeh Nazari synthesized two novel vinyl-linked covalent organic frameworks (VCOFs), materials designed to extract gold ions and nanoparticles from discarded circuit boards. Among them, one VCOF showed exceptional selectivity, absorbing 99.9% of gold while avoiding other metals like nickel and copper.
"We can use gold-containing COFs to convert carbon dioxide into useful chemicals and by converting carbon dioxide into value-added materials, we not only reduce the demand for waste disposal, but also provide environmental and practical benefits. It's a win-win for the environment," he added.
The rising demand for gold requires innovative methods for its recovery from e-waste. The method presents the synthesis of two tetrazine-based vinyl-linked covalent organic frameworks, including TTF-COF and TPE-COF that adsorb gold ions and nanoparticles and catalyze the carboxylation of terminal alkynes. These covalent organic frameworks have low band gaps and high photocurrent responses. TTF-COF has an adsorption capacity toward aqueous Au(III) of 2440 mg g–1, and TPE-COF’s Au(III) adsorption capacity is 1639 mg g–1.
The gold source is metal flakes isolated from waste computer processing units. Of the gold present, > 99% is selectively captured by TTF-COF whereas only 5% of the Ni and 2% of the Cu in the solution is adsorbed. The Au-loaded covalent organic frameworks catalyze the carboxylation of terminal alkynes and are stable and reusable for six reuse cycles. The covalent organic frameworks convert e-waste into a valuable catalyst for a useful green organic transformation.
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