DEVELOPMENT OF AN ELECTROCHEMICAL MICROBIAL SENSOR FOR ANALYTICAL
DETERMINATION OF Pb (II) IONS IN AQUEOUS SOLUTION
S. Vimalnath1, S. Subramanian1, S. Sampath2, R. V. Kumar3 and C. Schwandt3
1
Department of Materials Engineering, Indian Institute of Science, Bangalore -560012, India
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore -560012, India
3
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 OFS, UK
2
ABSTRACT
Waste waters and industrial effluents containing toxic heavy metals such as Pb, Hg, As and Cr,
beyond permissible limits pose serious threats to the ecosystem, when discharged into the environment. It
thus becomes imperative to monitor the concentration of the toxic heavy metals and treat them before
discharging. In this study with the above objective in mind, a microbial sensor has been developed using
P. aeruginosa cells drop coated onto a carbon paste electrode (CPE) for the detection of Pb (II) ions in
aqueous solutions. Detailed biosorption experments confirmed that complete bioremoval of lead could be
achieved using P. aeruginosa cells under optimum conditions of pH and biomass loading. For the
electroanalytical determination, the Pb (II) ions were initially preconcentrated on the P. aeruginosa
modified CPE, reduced and then anodically detected with oxidation of Pbo using differential pulse anodic
stripping voltammetry (DPASV) technique. All the experiments were carried out in the presence of 0.1 M
sodium acetate buffer and KNO3 as background electrolyte. The parameters namely pH, scan rate, biomass
loading, deposition potential, deposition time and concentration of Pb (II) ions were optimized for the
biomass modified CPE, to obtain maximum voltammetric response. Under the optimized conditions of pH
5.6, scan rate of 0.008 V s-1, biomass content of 1.7-1.8x109 cells mL-1, deposition potential of -1.2 V, and
deposition time of 500 s, the developed microbial sensor showed a linear response for the peak current
between 0.5x10-5 M and 1x10-8 M of Pb (II) ions with the R2 value of 0.9979. The lowest limit of detection
(LLOD) was determined as 8.02x10-7 M of Pb (II) ions. The redox mechanisms of Pb (II) ions on the P.
aeruginosa modified CPE surface are discussed.
KEYWORDS
Bio-sensor, Pseudomonas aeruginosa, Pb(II) , CPE, DPASV, LLOD