Ammonium ion sensor based on SiO2/ZrO2/phosphate-NH4+ composite for quantification of ammonium ions in natural waters

Cláudia F B Coutinho,Rení V S Alfaya,Crystian G Rocha,Antonio A S Alfaya,Débora A De Jesus,Alfredo A Muxel,Yoshitaka Gushikem,Flaveli A S Almeida

doi:10.1590/s0103-50532007000100022

Cláudia F B Coutinho, Rení V S Alfaya + Show 6 more

Open Access

https://doi.org/10.1590/s0103-50532007000100022

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Abstract

Ion selective-electrode was constructed and evaluated for determination of ammonium ions in natural waters. The electrode consists of paste carbon with the composite SiO2/ZrO2/phosphate-NH4+ obtained through sol-gel process. The electrode exhibits a sub-Nernstian response for ammonium concentrations between 7.7´10-7 and 4.0´10-2 mol L-1 and a detection limit of 1.58´10-7 mol L-1 (8.5´10-3 ppm). The electrode response for ammonium was fast (1 minute). The selectivity coefficients KpotA,B for several ions usually present in natural waters were determined applying the matched potential method. The potentiometric method with the ion selective electrode was validated by the Berthelot method (standard method), through the determination of ammonium ions in natural waters. The ion selective-electrode proved suitable for routine quality control of natural waters by potentiometry.

Highlights

The presence of ammonium ions in rivers and lakes can be associated in most cases to pollution caused by livestock, intensive agriculture and mainly, nowadays, to liberation of domestic sewage in courses of superficial waters in an indiscriminate way and in larger and larger amounts.Ammonium ion sensor is a useful tool in environmental pollution control,[1] food and clinical analysis[2,3,4] and other industrial applications.[5]
Within the magnification used (× 1000), it is very clear that the oxide particles are highly dispersed and no evidence of metal oxide island formation is detected
The interference of ions which are normally found in natural waters such as Fe3+, Mg2+, Mn2+, Ca2+, Na+, Li+ and K+, which could interfere on the electrode response, was verified by determining the Kpot of the membrane potential was observed, which could be explained by total proton exchange of the phosphate groups of SZP composite

Summary

Introduction

The presence of ammonium ions in rivers and lakes can be associated in most cases to pollution caused by livestock, intensive agriculture and mainly, nowadays, to liberation of domestic sewage in courses of superficial waters in an indiscriminate way and in larger and larger amounts.Ammonium ion sensor is a useful tool in environmental pollution control,[1] food and clinical analysis[2,3,4] and other industrial applications.[5]. Ion selective-electrode was constructed and evaluated for determination of ammonium ions in natural waters. The selectivity coefficients for several ions usually present in natural waters were determined applying the matched potential method.

Results

Conclusion