Investigation on square wave and cyclic voltammetry approaches of the Pb2+, Cd2+, Co2+ and Hg2+ in tap water of Beni Mellal City (Morocco)
Charaf Laghlimi, Abdelaziz Moutcine, Morad Elamrani, Abdelilah Chtaini, Jalal Isaad, Hamza Belkhanchi, Younes Ziat
Abstract
ABSTRACT A sensitive sensor has been prepared to detect and quantify electrochemically Pb 2+ , Cu 2+ and Co 2+ in drinking water. The objective of this work is to qualify the trueness and preciseness of two electrochemical methods which are the square wave (SWV) and the cyclic voltammetry (CV) with regard to the detection of lead, copper and cobalt ions in tap water. The electrode used for this purpose is modified with an organic molecule EDTA (ethylenediaminetetraacetic acid) of chemical formula (C 10 H 16 N 2 O 8 ) that we added to a specific amount of graphite carbon powder (CP). The formed paste is introduced into a cylindrical plastic cavity. This formed entity is attached to a carbon graphite rod to ensure the passage of the current. The detection limit and quantification limit of carbon-paste electrode CPE-1% EDTA for the reduction peak (CVPic-red) are the lowest, they are respectively 9.31 × 10 –10 mM and 3.1 × 10 –9 mM. The coefficient of variation (CV*) and repeatability uncertainty for measurements made by the SWV are lower compared to the CV. The SWV gives more accurate but not correct results while the CVPic-red gives correct but not accurate results. For all studied metals, the method is linear in the concentration range (0.6–2.1 mM), except for mercury it is linear in the range (0.3–2.1 mM). Cadmium has a low systematic error (SE = 0.009 mA/cm 2 ) followed by lead (0.013 mA/cm 2 ) then mercury.