Influence of the different carbon nanotubes on the development of electrochemical sensors for bisphenol A

Different methods of functionalisation and the influence of the multi-walled carbon nanotube sizes were investigated on the bisphenol A electrochemical determination. Samples with diameters of 20 to 170 nm were functionalised in HNO3 5.0 mol L− 1 and a concentrated sulphonitric solution. The morphological characterisations before and after acid treatment were carried out by scanning electron microscopy and cyclic voltammetry. The size and acid treatment affected the oxidation of bisphenol A. The multi-walled carbon nanotubes with a 20-40 nm diameter improved the method sensitivity and achieved a detection limit for determination of bisphenol A at 84.0 nmol L− 1.