Treatment of an Azo dye by citrate catalyzed photoelectro-Fenton process under visible light using carbon nanotube-polytetrafluoroethylene cathode

Degradation of C.I. Direct Red 23 (DR23) was investigated by photoelectro-Fenton (PEF) process in the presence of citrate catalyst under visible light irradiation of 6W. Multi walled carbon nanotubes (CNTs) were characterized by transmission electron microscopy (TEM), which had approximately internal and external diameters of 6 nm and 22 nm, respectively. CNTs were stabilized on carbon paper utilizing polytetrafluoroethylene (PTFE) and stabilization was confirmed by scanning electron microscopy (SEM). Results revealed that the degradation efficiency followed the order of PEF/citrate > PEF > EF at the same operational conditions after 90 min treatment of 20 mg/L DR23. The effect of some operational parameters such as applied current, initial pH, initial dye concentration and Fe(III) to citrate ratio on PEF/citrate process was studied. Artificial neural network (ANN) was applied not only to develop a model to predict the degradation efficiency with reasonable performance (R²= 0.988), but also to determine the relative importance of operational parameters for PEF/citrate process.