The experimental study of a hybrid solar photo-Fenton and photovoltaic system for water purification

Highlights: • A new solar photo-Fenton and photovoltaic system was performed for the first time. • Acid Red 26, Malachite Green and Reactive Blue 4 were discolored using the system. • The PV panel of the hybrid system could work under lower temperature. • The system achieved self-sufficient energy and could work autonomously. • Solar spectrum could be made full use for power generation and water purification. - Abstract: A new hybrid system that integrated a photovoltaic (PV) panel with a solar photo-Fenton (SPF) reactor was constructed to treat wastewater and generate electricity for the first time. The decolorization and photovoltaic performances of the hybrid system were tested outdoors by discoloring three dyes: Acid Red 26 (AR26), Malachite Green (MG) and Reactive Blue 4 (RB4). Lab scale experiments also had been done to confirm the impact of temperature on the SPF process. The lab scale results show that SPF process was more efficiency for decoloring the different dyes, compared with dark Fenton. The SPF followed a pseudo-first-order reaction and the reaction rate constant was improved about 3.5, 4.5 and 0.61 times for AR26, RB4 and MG respectively as the wastewater temperature increased from 20 to 50 °C. The decolorization difficulty of the three dyes followed this order: MG > AR26 > RB4. The results of the hybrid systems tested outdoors show that 200 mg/L MG had achieved 98.6% color removal after 3 h of treatment at a low catalyst dose (Fe²⁺ = 5 mg/L) under sunlight. For 100 mg/L MG, 99.3% color removal was observed after 70 min. The treatment time required for decolorization of AR26 and RB4 was more shorter. In the present of the water layer, the wastewater temperature was increased and that of the hybrid system was decreased. The average output power of the hybrid system was more than 12 W and sufficient to drive the system during all of the outdoor experiments. Our results suggest that the system could realize decolorization of different dyes and automatic operation.