Anodic behavior of platinum electrodes in sulfide solutions and the formation of platinum sulfide

Electrochemical oxidation of sulfide ion at a boron-doped diamond anode

“…Sulfur species are known to associate strongly with at least some of these anodes (Au, Pt) [19][20][21][22][23][24]. The high E value at BDD explains why oxidation all the way to sulfate is favoured at this anode.…”

Electrochemical oxidation of sulfide ion at a Ti/IrO2–Ta2O5 anode in the presence and absence of naphthenic acids

“…The S 2p spectrum of an anode that had been used several times and then thoroughly rinsed with water indicated the presence of sulfate ion (33%), sulfite (52%), bisulfide (8%) and either polysulfide or elemental sulfur (8%). The corresponding effect is well known at Pt anodes, at which the PtO x layer formed under anodic polarization is converted to an insoluble Pt sulfide when the electrolyte contains sulfide ions [22]-although there is a report [23] that elemental sulfur deposited on a Pt anode at potentials \0.2 V versus SCE; this redissolved as polysulfide in the presence of excess sulfide ion. Similar behaviour is observed at gold [24]; sulfur deposition hinders the further oxidation of sulfide, except at high potentials when the sulfur is oxidized further to sulfate [25].…”

Electrochemical removal of sulfur pollution

“…Nevertheless, these were soon found non-suitable, especially for industrial wastewater desulfurization, as they not only suffer from passivation (Dutta et al, 2009b), but they can also be oxidized already at low potentials (E 0 CO2/C = 0.207 vs SHE), leading to electrode dissolution for potentials typically above 1.1 V vs SHE (Fabbri et al, 2014;Yi et al, 2017). Electrocatalytic surface loss and poisoning, as well as subsequent decrease of sulfide oxidation kinetics have also been reported for boron doped diamond (BDD) electrodes (Lawrence et al, 2002;Waterston et al, 2007) as well as for non-carbon-based anodes, such as platinum (Al-Kharafi et al, 2010;Ramasubramanian, 1975), nickel (Behm & Simonsson, 1999) and titanium-oxide electrodes (El-Sherif et al, 2010).…”

“…Studies on the effect of sulfide oxidation on different electrode materials, and vice versa, initiated the field of direct electrochemical desulfurization around 50 years ago (Hamilton & Woods, 1983;Ramasubramanian, 1975). Since then electrochemical sulfide oxidation has been studied extensively, mainly due to the fact that sulfide oxidation to S 0 readily occurs at a low potential (E eq = −0.419 at pH 12, Table 8.3), possibly allowing for low operational voltages, i.e.…”