Analytical Study of ion–selective electrodes using nanoparticulate ZnO

Abstract

Zinc Oxide nanoparticles (NPs) were prepared from raw materials via a microwaveassisted method. The ZnO NPs were characterized by X-ray Diffraction (XRD) and scanning electron microscopy (SEM). NPs were approximately 22.5 nm in size, as calculated using the Scherrer formula from the most intense XRD peak. The ZnO NPs were compared with ZnO microparticles (MPs) through thermal analysis (thermogravimetry TG, derivative thermogravimetry DTG, and differential thermal analysis DTA). A Zn2+-selective electrode based on polyvinyl chloride was prepared using ZnO NP powder and di-butyl phthalate, and then the analytical specifications of the ZnO NP and ZnO MP electrodes were compared. The ZnO NPs and ZnO MPs electrodes respectively had linear ranges of 10−2– 10−5 and 10−2–10−4 M, Nernstain slopes of 28.71 and 27.79 mV/decade, correlation coefficients of 0.999 and 0.999, detection limits of 1.371 × 10−7 and 2.513 × 10−6 M, quantitative limits of 4.569 × 10−7 and 8.383 × 10−6 M, and response times of 9–39 and 13– 36 s respectively. The lifetime of each electrode was 11 day. The optimum conditions for each electrode were pH 5–8, 25–30 °C temperature, and 10−3 M filling solution concentration. The selectivity of the electrodes was measured in different solutions, and results showed that the selectivity coefficient values for all interference ions were less than one.