Time and calcination temperature influence on the electrocatalytic efficiency of Ti/SnO2:Sb(5%),Gd(2%) electrodes towards the electrochemical oxidation of naphthalene

Produced water is the largest volume wastewater associated with petroleum and gas production. Due to its diverse composition and large volume, produced water treatment is very challenging in order to avoid permanent or significant damages to the environment. On the other hand, the anodic material stability and the electrocatalytic properties are crucial for improved pollutant degradation efficiencies in electrochemical wastewater treatment. Here, we report the development of Ti/SnO2:Sb(5%),Gd(2%) electrodes by the polymeric precursor method, also known as Pechini method, for use in naphthalene electro-oxidation. The influence of the calcination time and temperature in the electrodes synthesis was investigated focusing on obtain an enhanced material with improved efficiencies in naphthalene oxidation. Thus, the Ti/SnO2:Sb(5%),Gd(2%) electrodes were calcined at 350, 400 and 450 °C during 1, 2 and 3 h for each temperature. Both temperature and time presented influence on the electrode electrocatalytic efficiency during naphthalene degradation, with emphasis on the calcination temperature influence. The most efficient electrodes are those calcined at 400 °C for 2 h, which degrade around 97% of the pollutant and reduce 86% of total organic carbon after 2 h of electrolysis at 2.0 V versus reversible hydrogen electrode. Besides that, they present the greatest rate constant coefficient of k = 1.41 mol−1 L min−1 and the greatest voltammetric charge density (13.75 mC cm−2) according to cyclic voltammetry measurements. Additionally, all the synthetized electrodes show high physical and electrochemical stability.