A voltammetric sensor based on the glassy carbon electrode modified with multi-walled carbon nanotube/poly(pyrocatechol violet)/bismuth film for determination of cadmium and lead as environmental pollutants

•A sensitive electrochemical sensor for detecting cadmium and lead ions.•The preparation and application of novel MWCNT's/poly (PCV)/Bi modifier film.•This combines surface area of MWCNT's, selectivity of PCV and non-toxicity of Bi.•The modification allows the rapid and sensitive determination of traces of analysts.•The sensor is reusable and cleaned with a simple electrochemical treatment. The performance of glassy carbon electrodes (GCE) coated with multi-walled carbon nanotube poly(pyrocatechol violet) composite and bismuth film was investigated as an electrochemical sensor in the simultaneous determination of Cd2+ and Pb2+ ions in a 0.1M acetate buffer solution at pH=5.0. The presence of the bismuth film improves the analyte accumulation due to its ability to form a fused alloy with cadmium and lead. It was found that the Bi-film modified electrode shows a better performance than the bare GCE, GCE-MWCNT and GCE-MWCNT/poly(PCV) electrodes. The parameters affecting the stripping current response were investigated and optimized. Under optimal conditions, the electrode showed a good linear response to Cd2+ and Pb2+ in the concentration range of 1.0–300.0μgL−1 and 1.0–200.0μgL−1, respectively. The detection limits were 0.20μgL−1 and 0.40μgL−1 for Cd2+ and Pb2+, respectively. It was found that the sensor has least interference from most of the common ions due to specific and selective interaction of the modifier functionalities with lead and cadmium ions. The response of the electrode remained constant for at least 3 weeks of successive operation. The proposed method was applied for simultaneous determining Cd2+ and Pb2+ contents in water samples.