VOLTAMMETRIC REDUCTION OF HYDROGEN-ION IN SOLUTIONS OF POLYPROTIC STRONG ACIDS WITH AND WITHOUT SUPPORTING ELECTROLYTE

Voltammetric reduction of strong polyprotic acids in solutions with ex cess and without supporting electrolyte was studied both theoretically and experimentally. A theoretical model based on the transport (diffu sion and migration) equations and the electroneutrality principle was used to compute voltammograms by finite difference simulation under bo th steady state and transient conditions. Simulated voltammograms are compared with experimental reduction curves obtained at platinum micro electrodes without and with excess electrolyte for two strong polyprot ic acids, sulfuric (H2SO4) and tungstosilicic (H4W12SiO40) acids. Perc hloric acid (HClO4) was used as the reference for comparison. The expe rimental results agree well with the calculated voltammetric curves bo th without and with excess supporting electrolyte. The dependence of v oltammetric response on the concentration of acids is also discussed. (C) 1997 Elsevier Science S.A.