Surfactant modified ZSM-5 zeolite as an active component of membrane electrode towards thiocyanate

A selective membrane electrode based on surfactant modified zeolite showed very good selectivity for thiocyanate anions over a wide variety of common inorganic and organic anions. The sensor displayed a near Nernstian slope of − 58.9 ± 0.9 mV per decade of the thiocyanate concentration. The working concentration range of the electrode was 1.00 × 10−6 to 1.10 × 10−1 M with a detection limit of 8.3 × 10−7 M thiocyanate. The response of the sensor to thiocyanate remained constant in the pH range of 2.0–10.1. The best performance was obtained with a membrane composition in the ratio of 25.5% PVC, 64.5% dioctyl phthalate and 10% surfactant modified zeolite ZSM-5. The sensor was highly selective for thiocyanate over a wide variety of other anions and exhibited a rapid response time of < 10 s over a period of 2 months with good reproducibility. Thus, this novel sensor may be applied as an indicator electrode in the argentometric titration of thiocyanate.

► Anion exchange property of SMZs retains in PVC matrix.
► A non Nersnstian behavior was observed for SMZs containing a high amount of surfactant.
► The proposed SMZ-PVC electrode showed a Nernstian response to thiocyanate.
► The proposed method can be used in direct and indirect potentiometry methods.