Ternary nanocomposites based on cellulose nanowhiskers, silver nanoparticles and electrospun nanofibers: Use in an electronic tongue for heavy metal detection

Contamination of water resources with heavy metal ions raises concerns because of their capability to accumulate in living organisms and cause serious health problems. As a consequence, the development of sensitive and reliable sensors capable to provide fast and accessible analysis of water quality regarding heavy metals is highly keen. Nanomaterials advancements have provided considerable improvements in these sensors, enabling efficient detection of different water pollutants even at extremely low concentration. In this work, we evaluated the performance of ternary nanocomposites based on electrospun nanofibers, cellulose nanowhiskers (CNW) and silver nanoparticles as sensing layers used in the electrical detection of heavy metals. These three materials were distinctly combined, resulting in six different sensors, which were arranged to compose an impedimetric electronic tongue. The synergism between the components could be verified by the enhancement of bulk conductance ability when CNW:Ag was combined with electrospun nanofibers. Adjustments of sensors and frequencies enabled efficient discrimination of distinct heavy metal ions. Moreover, the sensor array could distinguish pure water from aqueous solution contaminated with Pb2+ at concentrations as low as of 10 nmol L-1.