Modification of glassy carbon electrode with polyaniline/multi-walled carbon nanotubes composite: Application to electro-reduction of bromate

Bromate is recognized as an oxyhalid disinfection byproduct in drinking water. Polyaniline/multi-walled carbon nanotubes composite (PANI/CNT) was synthesized by in situ chemical oxidation and employed to investigate the electrocatalytic reduction of bromate. The introduction of CNT into PANI was proven by X-ray diffraction and transition electron microscopy. The prepared PANI/CNT composite presented better electrochemical performances than pure PANI. The electrochemical reduction of bromate occurred while polyaniline transformed from emeraldine into leucoemeraldine in acid solution. Besides, peak current of bromate reduction increased linearly with bromate concentration, indicating an analyte diffusion process. The activation energy for bromate reduction was calculated to be 10.98 kJ mol−1. Various initial bromate concentrations had different removal rates. The maximum removal rate of BrO 3 - at 10 mg L−1 (48.9%) was better than those at 50 mg L−1 (30.1%) and 100 mg L−1 (13.2%). Due to the persistent doping of bromide ions into polyaniline, the electrocatalytic performance of PANI/CNT decreased as the electrochemical reaction progressing.