Photo-Fenton process for simultaneous colored wastewater treatment and electricity and hydrogen production

The decolorization of Orange II (azo-dye) using a combination of the photo-Fenton process and electrochemical corrosion of iron, which can be used for wastewater treatment and electricity and hydrogen gas production simultaneously, was investigated. In order to quantitatively estimate experimental parameters such as ultraviolet (UV-A) light intensity, total iron ion concentration, hydrogen peroxide concentration, and Orange II concentration, a dynamics simulation of the proposed combined process for continuous decolorization was developed. As the total iron ion concentration and UV-A light intensity increased, the decolorization rate constant increased. The decolorization improved as the hydrogen peroxide concentration increased until a critical hydrogen peroxide concentration was achieved. An increase in the initial Orange II concentration depressed the photo-Fenton decolorization. The proposed model satisfactorily simulated the present experimental results for both batch and continuous systems. It can provide valuable information for reaction kinetics, start-up and shut-down operations, and operability studies, as well as steady-state performance. The electric current and amount of hydrogen gas obtained using the combined process were 3.8 mA and 1.88 × 10−3 mmol/min, respectively.

• The process consists of the photo-Fenton process and corrosion of an iron electrode. • The process achieves wastewater treatment and energy production simultaneously. • The model satisfactorily predicts the experimental results in the continuous process.