Anodic oxidation of organic pollutants on a Ti/SnO2–Sb2O4 anode

Abstract

A Ti/SnO 2 -Sb 2 O 4 electrode was prepared by alternate Sn and Sb electrodepositions using the thermoelectrochemical method. The chemical, electrochemical, and structural characterization of the electrode was performed and it was tested in the anodic oxidation of several pollutants, phenol, ibuprofen, acid orange 7 (AO7), and diclofenac, all in aqueous 0.035 M Na 2 SO 4 solutions at current densities of 10 and 20 mA cm -2 . After the 24 h assay, removal of chemical oxygen demand, total organic carbon (TOC) and absorbance were very high, especially at the higher current density. TOC removals presented the lowest value. However, after 24 h at 20 mA cm -2 , TOC removals were: phenol-94%; ibuprofen-83%; AO7-88%; and diclofenac-73%. Combustion efficiency and instantaneous and mineralization current efficiencies were also determined.

The Oxygen Evolution Reaction at Sn-Sb Oxide Anodes: Influence of the Oxide Preparation Mode

“…When the Sn and Sb electrodepositions were alternated (Figure 1b and 1e), the formation of distinct Sn or Sb oxide phases was observed: SnO 2 (PDF#41-1445) and Sb 2 O 4 (PDF#11-0694) or Sb 2 O 3 (PDF#43-1071). This fact is in agreement with what was previously observed in the cases of Ti/SnO 2 -Sb 2 O 4 , 23 with a different electrodeposition time from the one prepared in this work, and Ti/Pt/SnO 2 -Sb 2 O 4 , 15 although antimony presents a different oxidation state when copper is the interlayer, possibly due to competition between copper and antimony for the oxygen. A SnSb intermetallic phase (PDF#33-0118) can be detected in almost all of the diffractograms.…”

“…Comparing the Ti/SnO 2 -Sb 2 O 4 (R f = 19), prepared in this work, with Ti/SnO 2 -Sb 2 O 4 (R f = 777), prepared in a previous work, 23 both by alternating metal electrodeposition but different electrodeposition durations, it can be concluded that a fourfold increasing in the electrodeposition time increases the roughness. The main differences found in the roughness factors for the Sn-Sb oxide films prepared on Ti/Pt or Ti/Cu must be due to the interlayers of Pt or Cu that present completely different aspects (see Figure 2b and 2c).…”

“…In Figure 3c and 3d, Ti/SnO 2 -Sb 2 O 4 , prepared with a shorter deposition time than the one presented in, 23 shows a different morphology from the cracked mud view that characterizes these films. 16,27 This fact is related to the higher homogeneity obtained in the films prepared with shorter deposition times that prevents a higher separation of the two phases, with different thermal expansion coefficients.…”

“…In the materials prepared with a Pt or Cu electrodeposited interlayer (Figure 1c and 1d), Pt or Cu diffraction lines were, respectively, identified. When the Sn and Sb electrodepositions were alternated (Figure 1b and 23 with a different electrodeposition time from the one prepared in this work, and Ti/Pt/SnO 2 -Sb 2 O 4 , 15 although antimony presents a different oxidation state when copper is the interlayer, possibly due to competition between copper and antimony for the oxygen. A SnSb intermetallic phase (PDF#33-0118) can be detected in almost all of the diffractograms.…”

Annealed Ti/Zn-TiO2 nanocomposites tested as photoanodes for the degradation of Ibuprofen

“…BDD electrodes are well recognized by their excellent proprieties (low background current, wide working potential window) and their main disadvantage (its high price). Other materials like Ti/Pt/PbO 2 and Ti/SnO 2 -Sb 2 O 4 oxide anodes were also used in the electro-oxidation of Ibuprofen, with very high degree of mineralization after 24 h of degradation [22,23]. Comparatively to the published studies, the materials prepared in this study are cheap, photoactive with high surface area leading to a significant photoconversion efficiency that makes them adequate photoanodes for the degradation of Ibu.…”