Selenium‐doped Graphite for Electrochemical Sensing and Adsorption of Hg(II) and Cd(II) Ions.

Selenium‐doped Graphite (Se‐DG) has been used for electrochemical (EC) sensing and adsorption of poisonous Hg(II) and Cd(II) ions which can produce acute toxic effects on various organs. Hence, detection and efficient removal of both the metal ions from aquatic sources are very crucial. Herein, square wave anodic stripping voltammetry (SWASV) method was applied for EC detection using Se‐DG coated glassy carbon electrode (GCE) as a working electrode. Corresponding EC responses were observed due to the interaction between the sensing surface and the analytes. Elemental Se (Se0) present in Se‐DG played a crucial role in EC sensing. The limit of detection (LoD) of Hg(II) and Cd(II) were observed to be 4.3 ppb and 1.9 ppb respectively. The limit of quantification (LoQ) were found as ppb 14.3 ppb and 6.3 ppb respectively. Batch method was carried out for adsorption of the same carcinogenic metal ions on the Se‐DG surface. Ultra‐trace concentration of the metal ions was determined in Inductively Coupled Plasma Mass Spectrometry (ICP‐MS). Maximum adsorption capacity (QM) for Hg(II) and Cd(II) were found 210.81 mg g−1 and 205.53 mg g−1 respectively from Langmuir fit. The adsorption process was spontaneous and endothermic and it could be better fitted by a pseudo‐second order rate law, suggesting a chemisorption over physisorption. X‐Ray Photoelectron spectroscopy (XPS) was performed to investigate the binding interaction of different functionalities present in Se‐DG with metal ions. [ABSTRACT FROM AUTHOR]