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Title of the thesis: Electrochemically-assisted aqueous reduction and its application for surface functionalization

Thesis defender: Reima Herrala
Opponent: Prof. Jon Ustarroz, Universite Libre de Bruxelles (VUB), Belgium
Custos: Prof. Jaana Vapaavuori., Aalto University School of Chemical Engineering

In the production and recycling of metals, it is important to valorize as much of the valuable metals in the feed as possible. However, valuable metals like gold and platinum are often found in very small quantities relative to base metals, and this complicates their recovery. The focus of this thesis is a novel method, which aims to selectively recover noble metals from solutions with large concentration differences through electrochemical plating.

In addition to the new method, this thesis stands out from others in the field by focusing on the use of the metal coated surfaces as functional materials. In practice, this means that the neoble metals are directly recovered onto a surface where they can participate in reactions such as carbon dioxide conversion to useful chemicals. For this purpose, the presented research also includes the preparation of porous and electrically conductive carbon surfaces from lignin, a side product of pulping. This way, circular economy practices are advanced in the preparation of functional materials.

The research shows that the novel EAR (Electrochemically-assisted Aqueous Reduction) works for the selective recovery of gold and platinum. The work focused on solutions rich in copper and iron chlorides, as they can be used in the leaching of precious metals from both primary and recycled raw materials. The work further showed that by adjusting the electrochemical parameters (i.e. potential, current) the efficiency, rate, and selectivity of the recovery could be adjusted, as well as the form of the recovered metal.

Keywords: electrochemistry, carbon surfaces, noble metals

Thesis available for public display 7 days prior to the defence at . 

Contact information: 
reima.herrala@aalto.fi 
Multifunctional Materials Design
Hydrometallurgy and Corrosion (Hydromet)