Julia Järlebark, Physics

​Title of thesis: Electrochemical investigations of Pt–Hg and Cu–Hg alloys for mercury decontamination purposes

   (password 229865)

Abstract

Mercury is a heavy metal of large environmental concern due to its potential to spread and bioaccumulate and to its high toxicity for all living organisms. To date, there is no method capable of efficient and sustainable removal of mercury from aqueous solutions under a wide range of conditions. The focus of this thesis is to investigate several aspects of mercury removal by electrochemical alloy formation between mercury and platinum or copper. Mercury ions in the solution are reduced by the application of an electric potential, and forms an alloy with a solid platinum or copper electrode. Using an electrochemical quartz crystal microbalance, the temperature dependence of the alloy formation between mercury and platinum is studied in the range 20–60 °C, and the apparent activation energy of the reaction is determined to be 0.29 eV. Another purpose of the thesis is relating the structure of the electrode at various length-scales to the rate of mercury removal. The electrochemical surface area is determined by underpotential deposition of hydrogen and by measurements of the electrical double-layer capacitance, and the electrode structure is studied using a scanning electron microscope. Mercury removal rates are determined through batch experiments with subsequent inductively coupled plasma mass spectrometry analysis. It can be concluded that a macroscopic surface area enhancement, e.g. in the form of a metal foam, generates an enhanced rate of mercury removal, while a porosity on the microscopic level, such as a porous platinum black structure, does not contribute to an increased mercury removal rate. Two case studies investigating the applicability of the technology are also performed within the thesis; removal of mercury from concentrated sulphuric acid produced in a commercial smelting plant and from a flue gas condensate from a combined heat and power plant. Mercury is successfully removed from the flue gas condensate using platinum coated titanium fibre electrodes, and from the sulphuric acid using platinum coated stainless steel electrodes. 
​​Supervisor: Björn Wickman
Examiner: Björn Wickman
Opponent: Oskar Vallhagen
Category Student project presentation
Location: Online via Zoom
Starts: 12 April, 2021, 11:00
Ends: 12 April, 2021, 12:00

Page manager Published: Mon 29 Mar 2021.