Removal of four dyes from aqueous medium by the peroxi-coagulation method using carbon nanotube-PTFE cathode and neural network modeling

The peroxi-coagulation process has been used for treatment of aqueous solutions of four dyes with different structures, namely C.I. Basic blue 3 (BB3), Malachite green (MG), C.I. Basic red 46 (BR46) and C.I. Basic Yellow 2 (BY2) at pH 3.0. The experiments were conducted using an open, undivided and cylindrical glass cell in the presence of sulfate electrolyte media with a carbon nanotube-polytetrafluoroethylene (CNT-PTFE) electrode as cathode. Outer and inside diameters of used carbon nanotube were 8-15 nm and 3-5 nm, respectively. Up to 90% decolorization of each of the dyes occurred in less than 10 min. BY2 has been used as a model among the dyes to study the effect of operational parameters, modeling of process by artificial neural networks (ANN) and calculating operation costs. TOC measurements of the BY2 and mixed dyes showed 92% and 93% decontamination at 6 h, respectively. Relationship between the predicted results of the designed ANN model and the experimental data was also conducted. The ANN model yielded a determination coefficient of R² = 0.989 and could describe the decolorization efficiency under different conditions. Our results also showed that the peroxi-coagulation process with CNT-PTFE electrode as cathode could removal 95% and 90% of BY2 and mixed dyes in 40 min from a real wastewater. The operation cost for decolorization of the dye solution containing BY2 was calculated (≈21.7 US$ (kg_{dye removed})^-1).