Application of surfactant modified zeolite membrane electrode towards potentiometric determination of perchlorate

Abstract

Potentiometric electrodes based on the incorporation of surfactant-modified zeolite Y (SMZ) particles into poly vinyl chloride (PVC) membranes were described. The electrode characteristics were evaluated regarding the response towards perchlorate ions. PVC membranes plasticized with dioctyl phthalate and without lipophilic additives (co-exchanger) are used throughout this study. The influence of membrane composition on the electrode response was studied. The electrode exhibited a Nernstian response towards perchlorate in the concentration range of 7.9×10−6–8.0×10−2M with a slope of 59.7±0.9mV per decade of perchlorate concentration with a working pH range of 1.7–9.5 with a fast response time of ≤10s. The lower and upper detection limits were 4.07×10−7 and 0.13M, respectively. The electrode response to perchlorate remains constant in the temperature range of 20–40°C and in the presence of 2.5×10−6–1×10−2M NaNO3. The selectivity coefficients for perchlorate anion as test species with respect to other anions were determined. The proposed modified zeolite-PVC electrode can be used for at least 30days without any considerable divergence in potential. It was applied as indicator electrode in water samples with satisfactory results. The results of this study and our previous work show HDTMA plays different roles according to the zeolite type and matrix, as HDTMA-zeolite Y in a carbon paste matrix showed a good Nernstian behavior towards phosphate anion.