Simultaneous voltammetric detection of ammonium and nitrite from groundwater at silver-electrodecorated carbon nanotube electrode

• Published in: Process safety and environmental protection 2017-05, Vol.108, p.18-25
• Main Authors: Baciu, Anamaria, Manea, Florica, Pop, Aniela, Pode, Rodica, Schoonman, Joop
• Format: Article
• Language: English
• Subjects: Ammonium; Carbon; Carbon nanotubes; Carbon-epoxy composites; Chemical compounds; Composite materials; Drinking water; Electrochemical techniques; Electrodes; Groundwater; Groundwater pollution; Nanoparticles; Nanotechnology; Nanotubes; Nitrite; Nitrites; Oxidation; Silver; Silver-electrodecorated carbon nanotubes-epoxy composite electrode; Simultaneous voltammetric detection; Spectrophotometry; Voltammetry; Water management
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2016.05.006

•Silver-electrodecorated carbon nanotubes-epoxy composite electrode.•Simultaneous voltammetric detection of ammonium and nitrite in water.•High sensitivity reached by differential-pulsed voltammetry technique.•Direct application in real water without deliberately adding supporting electrolyte. Ammonium and nitrite are listed by Water Framework Directive as core parameters that should be monitored for the groundwater as drinking water source. This work describes the sensitive protocols for the simultaneous detection of ammonium and nitrite in water at a new silver-electrodecorated carbon nanotubes-epoxy composite electrode (Ag-CNT) using advanced voltammetric technique. A carbon nanotubes-epoxy composite electrode obtained by two-roll mill procedure was decorated electrochemically with silver nanoparticles. This new electrode displays excellent electrocatalytic activity towards the direct oxidation of ammonium and nitrite at well separated less potential values (+0.15V/SCE for ammonium and +0.7V/SCE for nitrite). Very good detection sensitivities (0.613mAmM−1 for ammonium and 0.980mAmM−1 for nitrite) and the lowest limits of detection (1μM for ammonium and 0.7μM for nitrite) were achieved by differential-pulsed voltammetry (DPV) under optimum operating conditions of 0.05V step potential, 0.2V modulation amplitude and the scan rate of 0.05Vs−1. This detection protocol was successfully applied to the simultaneous determination of ammonium and nitrite in groundwater samples, and the results were found to be consistent with the values obtained by the standardized spectrophotometry methods.