Sorption and determination of Hg(II) on clay modified carbon paste electrodes

Sorption of mercury(II) both in cationic and in anionic form was studied by means of carbon paste electrodes modified with typical clay minerals (montmorillonites) and with mica (biotite). Significant anionic exchange of montmorillonites was found in complexing media such as solutions containing acetates and chlorides. Anionic sorption of [HgCl4](2-) can be used for the determination of Hg(II) in media with high content of chlorides. Linear calibration dependences were found in the concentration range 1.24 x 10(-7)-9.86 x 10(-7) mol/l (10 min accumulation at -1.2 V) and in the range 4.9 x 10(-8)-1.74 x 10(-7) mol/l (15 min accumulation). Model samples of table water and saline water were analysed. (C) 1999 Elsevier Science B.V. All rights reserved.