PRELIMINARY INVESTIGATION OF A BIOELECTROCHEMICAL SENSOR FOR THE DETECTION OF PHENOL VAPORS

• This work investigates the feasibility of constructing a bioelectrochemical sensor that can operate directly in gases. A series of experiments are described, resulting in a sensor that is responsive to phenol vapours. The sensor was based on ionically conducting films that incorporate a biological redox catalyst at the surface of an array of interdigitated microband electrodes. Exposure to phenol vapour drives the bioelectrochemical reaction, providing a basis for a current signal under constant potential conditions. Ionic materials included Nafion and films based on tetrabutylammonium toluene-4-sulphonate (TEATS). The quasi-reversible electrode reaction of potassium hexacyanoferrate (II) within TEATS was investigated as a function of drying time. E(0) and k(0) were determined at a TEATS modified microdisc electrode under steady-state conditions. Drying time (water loss) from the TEATS film had the effect of increasing the film ionic strength. It was shown that as the film ionic strength increased, E(0) for potassium hexacyanoferrate (II) shifts toward positive potentials (because of ion pairing) and there was a corresponding increase in the heterogeneous rate constant, k(0). The latter effect was attributed to increasing ion-ion (cation-ferrocyanide ion) interactions as the film dried and the enhancing effect this had on the prevention of surface poisoning reactions at the electrode. These factors are discussed in relation to sensor design.

Nyckelord

BIOELECTROCHEMISTRY; PHENOL SENSOR; GAS-PHASE; IONIC FILMS; MICROELECTRODES; STEADY-STATE VOLTAMMETRY

TECHNOLOGY

TEKNIKVETENSKAP

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