Ion exchange membrane separated two electrode flow analyzer for continuous aqueous electrochemical heavy metal detection

An array of two or more electrochemical cells for detecting heavy metals in water, comprising:

• a first electrochemical cell comprising:
• a first gas diffusion counter/reference electrode;
• a first flooded flow through working electrode comprising a porous, hydrophilic media coated with a physically vapor deposited gold (Au) surface;
• a first flooded zone;
• and
• a first ion exchange membrane comprising a first ion exchange membrane composition selected based on a heavy metal being detected and disposed to separate the first gas diffusion counter/reference electrode and the first flooded flow through working electrode;
• a second electrochemical cell comprising:
• a second gas diffusion counter/reference electrode;
• a second flooded flow through working electrode comprising a porous, hydrophilic media coated with a bismuth surface;
• and
• a second ion exchange membrane comprising a second ion exchange membrane composition selected based on a heavy metal being detected that is disposed to separate the second gas diffusion counter/reference electrode and the second flooded flow through working electrode to form an anoxic environment around the gas diffusion counter/reference electrode;
• a gas inlet in communication with the first gas diffusion counter/reference electrode and the second gas diffusion counter/reference electrode connected to a hydrogen source that is external to the electrochemical cell;
• a water inlet in communication with the first flooded flow through working electrode and the second flooded flow through working electrode and configured to be connected to a water source that is external to the electrochemical cell;
• a second flooded zone;
• and wherein:
• each working electrode is configured to receive deposition of a heavy metal on a surface of the working electrode, and configured to remove the heavy metal from the surface of the working electrode;
• the first flooded flow through working electrode is positioned in the first flooded zone and separated from the first gas diffusion counter/reference electrode by the first ion exchange membrane, wherein the first ion exchange membrane directly contacts both the first flooded flow through working electrode and the first gas diffusion counter/reference electrode;
• and
• the second flooded flow through working electrode is positioned in the second flooded zone and separated from the second gas diffusion counter/reference electrode by the second ion exchange membrane, wherein the first ion exchange membrane directly contacts both the first flooded flow through working electrode and the first gas diffusion counter/reference electrode.

A method of continuous fluid analysis for heavy metals in water using a multi-electrode flow analyzer, comprising:

• passing an aqueous sample through a first water inlet flow area and into a flooded flow working electrode of a multi-electrode flow analyzer;
• passing a gas mixture through a second gas inlet flow area and into a gas diffusion counter/reference electrode of the multi-electrode flow analyzer;
• depositing an analyte onto a surface of the working electrode, which comprises a physically vapor deposited gold (Au) film;
• stripping the analyte from the surface of the working electrode by sweeping a range of a potential applied to the surface of the working electrode;
• and
• determining a peak current over the range of the potential to determine a quantity of analyte deposited on the working electrode;
• and wherein:
• the flooded flow through working electrode is positioned in a flooded zone and separated from the gas diffusion counter/reference electrode by an ion exchange membrane, the ion exchange membrane comprising a composition selected based on a heavy metal being detected and disposed to directly contact both the flooded flow through working electrode and the gas diffusion counter/reference electrode and separate the gas diffusion counter/reference electrode from the flooded flow through working electrode;
• the water inlet is configured to be connected to a water source that is external to the multi-electrode flow analyzer;
• and
• wherein the gas inlet is connected to a hydrogen source that is external to the multi-electrode flow analyzer.