New Strategy of Using Stannic Oxide as Catalyst in a Three-dimension Electrode Reactor for the Electro-oxidation of Organic Matter

Abstract

An efficient organic-matter (OM) degradation strategy using synthetic electrocatalysis particles as fixed filler in a threedimension electrode reactor was developed. In our work, SnO2-granular active carbon (SnO2-GAC) was prepared by integrating GAC with nano-SnO2 via the sol-gel method, using SnCl4 as starting material and gelatin as a stabilizer. The phase composition and micromorphology of the particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning/transmission electron microscopy techniques. The results showed the incorporation of SnO2 crystallized in a tetragonal lattice with an average crystallite size of 10.6 nm, which was easily accessible on the GAC surface and mesopores. Electrochemical properties were tested with cyclic voltammetry and electrochemical impedance spectroscopy methods that disclosed an improved response current with a simultaneous increase in anodic area, while the charge-transfer and electrolyte resistance obviously decreased, in contrast to the virgin GAC filler in the three-dimension electrode system. Although the energy consumption of SnO2-GAC (11.71 kWh·kg−1 COD) presented slight superiority than that of GAC (13.62 kWh·kg−1 COD) at the same chemical oxygen demand (COD) conversion of 98 % when a current density of 20 A·m−2 was employed for phenolic wastewater treatment, the required degradation time of the former (47.22 h) is greatly decreased compared with that of the latter (54.24 h). These results obviously confirm the superiority of the prepared SnO2-GAC in electro-oxidation of organic matters.