Title: A sustainable nanotechnological approach for urban mining and recovery of strategic elements

Henrique E. Toma

Institute Of Chemstry – University Of Sao Paulo, Brazil


Henrique E. Toma is professor of Chemistry at University of São Paulo, and a distinguished member of The World Academy of Sciences (TWAS) and Fellow of the John Simon Guggenheim Memorial Foundation. He has published 420 journal articles, receiving 10800 citations to date, in addition to 34 patents and 15 books. He is also the recipient of more than 20 international prizes, including the TWAS Award in Chemistry, Simon Mathias Medal (Brazilian Chemical Society), National Order of the Scientific Merit Award (Brazilian Ministry of Science and Technology), and the UNESCO Mercosur Award for Science and Technology.


Humanity is strongly dependent upon strategic elements, such as copper, nickel, cobalt, the noble metals and the rare earths, but the conventional mining processes are raising serious concerns because of the pollution and damage imparted to the environment. In this sense, a new process named magnetic nanohydrometallurgy (MNHM) has been recently developed in our Laboratory making use of engineered superparamagnetic nanoparticles for sequestering the elements and confine them,  using an external magnet (Nd2Fe14B), directly on the electrode surface. Such nanoparticles exhibit a crystalline magnetite core, protected with a silica coating which is treated with an aminoalkylsilane to link a complexing agent, such as DTPA (diethylenetriaminepentaacetic acid). After extensive characterization by FTIR, DLS, AFM, TEM, and confocal Raman spectroscopy, the nanoparticles can be employed in hydrometallurgy, for sequestering strategic metal ions, including the evaluation of their performance by means of their specific adsorption isotherms. In addition to their complexation performance, the magnetic nanoparticles containing the captured metal ions can be collected onto the electrodes in order to perform direct electrochemical deposition  in aqueous solution, at room temperature, without employing polluting organic solvents. After  electrodeposition, the magnetic nanoparticles are completely recovered, returning to the process, for a new batch procedure.  All the steps can be computer controlled and automated, minimizing the operational scale and improving the yield.  In this presentation, the extraction and recovery of strategic metals from urban mining will also be  discussed, as well as the application of MNHM in the separation of lanthanide elements.

Audience take away:

• It will be shown new green nanotechnological strategies which can be applied to the mineral area and environment. Such approach can be useful in water treatment, metal extraction, recycling and recover. It can help launching urban mining, dealing with a worldwide problem represented by the electronic waste.