Role of PtO on the Oxidation of Arsenic (III) at Pt RDE in 1M H2SO4 and 1M Na2SO4 through Linear Sweep Voltammetry Technique

Linear Sweep Voltammetry (LSV) has been conducted using platinum (Pt) disc electrode to investigate the effect of PtO on the Arsenic (III) oxidation. The changes of As(III) oxidation peak currents and peak potential in 1M H2SO4 and 1M Na2SO4 solutions have been evaluated. Effects of As(III) concentration, scan rate, rotation speed of the electrode on the oxidation of As(III) have been studied extensively. Oxidation peak current values increases linearly with the concentration, scan rate and electrode rotation speed in both of the media and the dependence plot goes through the origin, except in the case of square root of angular velocity and ipa in the Na2SO4 solution. A sharp increase in the As(III) peak current values are found in 1M H2SO4 but not in 1M Na2SO4 medium because of the formation of PtO is higher than in sulphuric acid medium with in the potential range of interest. The PtO layer blocks the available surface area for the As (III) oxidation. Presence of the PtO layer, shifts the As(III) oxidation potential to less positive, suggesting the PtO layer some how facilitates the oxidation of As(III) reaction.