Abstract Nitrogen oxide and sulfur dioxide concentrations present in a gaseous mixture are rapidly and continually monitored by measuring the current passing between an inert metallic sensing electrode and a counter electrode which electrodes are in contact with an aqueous electrolyte solution and at which sensing electrode the oxides are electrooxidized. The sensing electrode is composed of an inert metal, whereas the counter electrode is composed of an electroactive lead sulfate which is electrochemically reduced when electrically interconnected with the sensing electrode in the presence of the aqueous electrolyte solution. A variable voltage source maintains the potential at the sensing electrode at the desired level.
The method of claim 1 wherein said sensing electrode and said counter electrode are coupled through a current sensing device and a low impedance voltage bias source.
Claim 2
Dependent Claim
48 words
The method of claim 2 further comprising: maintaining said sensing electrode at a predetermined positive potential of about 0.80 volts relative to the standard hydrogen reference electrode whereby an indication of the concentrations of sulfur dioxide in said sample is provided by said measuring of the current flow.
Claim 3
Dependent Claim
48 words
The method of claim 2 further comprising: maintaining said sensing electrode at a predetermined positive potential of about 1.20 volts relative to the standard hydrogen reference electrode whereby an indication of the concentration of nitrogen oxides in said sample is provided by said measuring of the current flow.
Claim 4
Dependent Claim
40 words
The method of claim 1 further comprising: covering said active surface with a selectively permeable membrane readily permeable to said pollutant molecules and relatively impermeable to said electrolyte whereby the pollutant molecules diffuse through said membrane to said active surface.