An advanced investigation on a new algal sensor determining Pb(II) ions from aqueous media

Abstract

It has been well documented that heavy metal accumulation in environment is harmful for living organisms at even trace levels. A new voltammetric algal sensor based on Phormidium sp. modification for Pb(II) determination from aqueous solutions was developed, and selectivity of the biomass to Pb(II) was investigated comprehensively. Many important experimental parameters were performed by using electrochemical techniques, including cyclic voltammetry and differential pulse stripping voltammetry. The preconcentrated ions at open circuit were reduced by scanning the potential from -1.5 to 1.5 V and current values obtained were related to the concentration of Pb(II) in the solutions. The best peak values belonging to Pb(II) were achieved at pH 8.0 with 0.05 M Tris-HCl solution. Preconcentration time was selected as 10 min, and the sensor was found in a linear range from 5.0×10(-8) M to 2.0×10(-5) M Pb(II) (0.01-4.0 mg L(-1)) with a detection limit of 2.5×10(-8) M. Other analytical properties of the developed microbial biosensor were also investigated. According to the Fourier transform infrared attenuated total reflectance (FTIR-ATR) analyses, the possible functional groups involved in Pb(II) accumulation in the Phormidium sp. were defined as carboxyl, sulphoxide and alcoholic groups. A simple chemical modification by formaldehyde both enhanced Pb(II) determination and content of functional groups involving Pb(II) binding. The proposed usage form of Phormidium sp. does not need complicated immobilization procedures and expensive preliminary preparations.