An all-solid-state potentiometric sensor modified with multi-walled carbon nanotubes (MWCNTs) for silicate assessment and water-quality testing

A simple and cost-effective approach is proposed for silicate ion determination. The approach is based on designing an all-solid-state potentiometric sensor. The plasticized polyvinyl chloride (PVC) membrane sensor is based on the ion-association complex [Ni(bphen) 3 ] 2+ [SiO 3 ] 2− as a sensory recognition material. The sensor is modified with multi-walled carbon nanotubes (MWCNTs) as an ion-to-electron transducer material. The performance characteristics of the new silicate-selective electrode were evaluated using a potentiometric water-layer test, potentiometric measurements, impedance spectroscopy, and current-reversal chronopotentiometry. The developed electrodes exhibited a low detection limit (0.11 μg mL −1 ) over a wide linear range (4.0 × 10 −6 to 1.0 × 10 −3 M) and near-Nernstian sensitivity (slope = −28.1 ± 1.4 mV per decade). They presented a very short response time (